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Role of hepatitis C virus in dual and triple hepatitis virus infection
Role of Hepatitis C Virus in Dual and Triple Hepatitis Virus Infection YUN-FAN LIAW
Hepatitis B virus (HBV), hepatitis C virus (HCV), a n d hepatitis delta virus (HDV) s h a r e s a m e t r a n s m i s s i o n routes, t h u s dual or triple i n f e c t i o n m a y o c c u r a n d e v e n persist in the s a m e patients. A significant a m o u n t o f lite r a t u r e h a s a c c u m u l a t e d since t h e a d v e n t o f HCV assays. It is p e r t i n e n t to r e v i e w a n d e v a l u a t e t h e clinical a n d virological significance o f HCV in multiple h e p a t o t r o p i c viral infection. The r e p o r t e d series o n s e r o p r e v a l e n c e o f HCV i n d i c a t e that HCV is f o u n d in m o r e t h a n 10% o f HBV- o r HDV-infected patients w o r l d w i d e . Of the patients w i t h dual or triple i n f e c t i o n i n v o l v i n g HCV, t h o s e h a v i n g c o r e p l i c a t i o n o f v i r u s e s t e n d to h a v e s e v e r e a n d p r o g r e s s i v e liver disease that is resistant to i n t e r f e r o n therapy, in c o n t r a s t w i t h p a t i e n t s h a v i n g a single virus infection. Paradoxically, dual or triple hepatitis virus i n f e c t i o n s are a s s o c i a t e d w i t h viral interference. In particular, HCV exerts a s u p p r e s s i v e effect o n H B V a n d HDV and may enhance seroclearance of HBV antigens or e v e n u s u r p t h e role of p r e e x i s t i n g virus as t h e a g e n t for c o n t i n u i n g hepatitis. A l t h o u g h H B V a n d H D V m a y also s u p p r e s s HCV, it appears to be less effective. T h e s e findings clearly s u g g e s t t h e n e c e s s i t y o f m o n i t o r i n g patients w i t h H B V or H D V infectious. In v i e w o f c o m p l e x d y n a m i s m o f viral i n t e r a c t i o n in multiple h e p a t o t r o p i c virus infection, t h e i m p o r t a n c e o f HCV a s s a y in t h e clinical studies c a n n o t be o v e r e m p h a s i z e d . The basic m e c h a n i s m s that r e g u l a t e t h e viral interactions, in particular t h e i m p a c t o f HCV in dual or triple virus infectious, rem a i n to be investigated. (I-IEPATOLOGY1995;22:1101-1108.)
The cloning and sequencing of hepatitis C virus (HCV) have led to the development of serological tests for this virus. 1'2 Recent studies using these serological assays have confirmed that HCV is transmitted pri-
Abbreviations: HCV, hepatitis C virus; HBV, hepatitis B virus; HDV, hepatitis delta virus; HAV, hepatitis A virus; HBsAg, Hepatitis B surface antigen; NANB, non-A, non-B hepatitis virus; ALT, alanine transaminase; anti-HCV, antibodies against HCV; IgM, immunoglobulin M; OD, optical density; HCC, hepatocellular carcinoma; HBeAg, hepatitis Be antigen; IFN, interferon. From the Liver Research Unit, Chang Gung Memorial Hospital, Chang Gung Medical College, Taipei, Taiwan. Received February 21, 1995; accepted June 16, 1995. The work was supported in part by a grant from National Science Council (NSC84-2331-B-182-005 MH) and a grant from Prosperous Foundation, Taipei, Taiwan. Address reprint requests to: Yun-Fan Liaw, MD, Liver Research Unit, Chang Gung Memorial Hospital, 199, Tung Hwa North Road, Taipei 105, Taiwan. Copyright © 1995 by the American Association for the Study of Liver Diseases. 0270-9139/95/2204-001253.00/0
marily via parenteral routes similar to that of hepatitis B virus (HBV) and hepatitis delta virus (HDV), such as blood transfusion, parenteral drug abuse, and hemodialysis. 3-~ Other inapparent percutaneous or mucosal routes m a y also occur. Although HCV does not transmit as efficiently as HBV and HDV, those at risk for HBV or HDV infection are also at risk for HCV infection, and simultaneous or coinfections are possible. One such example is an intensive care nurse, who developed simultaneously infections of hepatitis non-A, non-B, and B viruses. 6 Because these viral infections m a y persist to cause chronic hepatitis or chronic carrier state, 7-9 superinfection of a new virus may occur and persist in patients who have been chronically infected with others. Earlier studies employing less sophisticated tests for hepatitis markers have already shown sequential or simultaneous acute infections by two or even four hepatitis agents. 8'1°'12 Acute hepatitis A virus (HAV) superinfection in chronic hepatitis B surface antigen (HBsAg) carriers was also well noted. ~3'~4HDV coinfection and superinfection in patients with HBV infection is well known since the wide use of HDV assays, s NonA, non-B hepatitis virus (NANB) superinfections have long been suspected to play a significant role in acute exacerbations during the course of chronic HBV infection, 15 or accounted for acute hepatitis in previously unrecognized HBsAg carriers. ~6 The advent of HCV assays has enabled investigators to examine the issues of HCV coinfection or superinfection more precisely. Several investigators have recently shown that dual or triple infection involving HCV is not uncommon. There is emerging evidence to suggest that HCV has significant clinical or virological implications in multiple hepatotropic virus infections, which is the objective of this review. COINFECTION WITH HBV AND H C V Simultaneous Acute Infections With NANB and HBV. In a study on the efficacy of a procedure for HBV
inactivation, Brotman et a117 showed that all 19 chimpanzees exposed to HBV alone developed HBsAg antigenemia within 4 to 9 weeks after the inoculation. Fifteen animals showed alanine transaminase (ALT) elevation with a peak level of 138 to 282 U/L (normal < 26). In contrast, of the 7 chimpanzees inoculated with NANB and HBV simultaneously, only 3 animals
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showed borderline ALT abnormalities and 5 developed been observed in India 24 and France. 2~ With respect HBsAg antigenemia. The onset of antigenemia was sig- to the earlier outbreak in Edinburgh, 19 the sera were nificantly delayed and the duration of antigenemia or retested for HCV RNA in as many cases as feasible. It clinical illness was shorter. They concluded that con- was found that there was significant disproportion of current NANB infection had probably interfered with HCV and HBV dual infection in patients with severe HBV replication and accounted for the delay and ame- or fatal illness, as compared with those who had moderlioration of clinical appearance of disease related to ate or mild/inapparent infection (Marmion BP, perHBV infection. A similar study by Hollinger et al is also sonal communication, 1994). Thus, coinfection with showed that simultaneous NANB infection interfered HCV and HBV can significantly increase the risk of with the development of HBV infection, either by de- fulminant hepatitis. Whether this is because of addilaying its onset or completely aborting it. tive effect of the hepatocyte damage by two concurrent In humans, simultaneous acute infections with viral infections or other unknown mechanisms requires NANB and HBV were first described in an intensive further study. Interestingly, the interaction between care unit nurse who needle-sticked her finger during HCV and HBV is similar to the obligatory interaction venipuncture of an HBsAg-positive uremic patient on between HDV and HBV in that the dual infection m a y chronic hemodialysis. Her clinical and serological cause a much more severe disease and m a y also result changes after the needle stick were characterized by in suppression of HBV replication. 28 late onset of an attenuated B hepatitis, that was preHCV S U P E R I N F E C T I O N IN CHRONIC ceded by an earlier onset of NANB hepatitis, sugHBV INFECTION gesting viral interference. 6 Besides this single case report, an outbreak of exceptionally severe hepatitis in Unless the onset of HBV and/or HCV infections was hemodialysis units was encountered in two Edinburgh clearly known and delineated serologically, such as in hospitals during 1969 to 1970.19 Dual infection with the setting of experimental superinfection in chimpanboth NANB and HBV was suspected. zees 27'2s or in the prospective follow-up study of paSimultaneous Acute Infections With HCV a n d tients with chronic hepatitis virus infections, 29 one can HBV. The stored serum specimens obtained during the hardly tell which virus comes first. The chronological chronic phase of the particular patients described sequences of seropositivity for HBsAg and anti-HCV above 6 were recently assayed for antibodies against can be prospectively documented in some patients, HCV (anti-HCV), and it was positive. Although acute such as hemophiliacs, parenteral drug abusers, and phase serum specimens of this patient were not avail- those on maintenance hemodialysis. 35'3°'31 In the case able to substantiate de n o v o seroconversion of anti- of clinical acute hepatitis, de n o v o seroconversion of HCV and immunoglobulin M antibody to hepatitis B anti-HCV in HBsAg-positive but IgM anti-HBc-negacore antigen (IgM anti-HBc), it is likely that she had tire patient indicates an acute HCV superinfection on acquired acute HCV and HBV coinfection, with ensuing chronic HBV state. 3'16'22 Presence of serum anti-HCV development of chronic hepatitis C. HBV and HCV with low enzyme immunoassay optical density (OD) coinfection is by no means rare. At least seven patients ratio in such patients also indicates acute HCV superwith concurrent posttransfusion acute HCV and HBV infection, if the OD ratios are increasing in the followinfection have been reported recently. 2°'21 In addition, up assays. In contrast, acute HBV superinfection in Krogsgaard et a122 re-evaluated their Copenhagen pa- patients with preceding or past HCV infection can be tients with acute hepatitis B observed during the years suggested by the presence of IgM anti-HBc as well as 1980 to 1982. They found that 3 (4.3%) of the 69 pa- anti-HCV of high OD ratio in the acute phase serum tients had acute HCV coinfection, and another 1 had samples. 22 HBV, HCV, and HDV triple coinfection by detecting de Seroprevalence studies in patients with HBsAg posin o v o anti-HCV seroconversion. Our recent study also tive chronic hepatitis, cirrhosis and hepatocellular carcishowed that around 10% of our patients with acute noma (HCC) have shown that dual infection with HBV hepatitis B were coinfected with HCV. The incidence and HCV is not uncommon in Asia, 32-38 as well as in of HCV may vary notably in different geographic areas. Western countries. 31'39-47 The prevalence is around 10% Similar to the findings of chimpanzee studies,~7'~s pa- to 15% in patients with chronic HBV infection, although tients with acute HBV and HCV coinfection generally it may vary from country to country. This is possibly have a delay in the appearance of HBsAg with short- because of different assay methods used 4s and the size of ened duration of HBsAg antigenemia, and a lower level the studies. The prevalence tends to be higher in studies of HBsAg and ALT as compared with patients with involving less than 100 patients (Table 1). The majority acute HBV infection alone. 2~ These observations sug- of patients with dual or triple infections are hepatitis B e gest that HCV coinfection interferes with HBV and at- antigen (HBeAg)-negative orantibodies against HBeAg tenuates its clinical presentation. However, we have (anti-HBe)-positive. 31 '34 .35. .43 . 49 50 also documented a serologically and virologically Suppression of HBV by HCV. Earlier studies in chimproven case of acute HCV and HBV coinfection pre- panzees showed that acute NANB (HCV) superinfecsenting as biphasic ALT elevation with fulminant hep- tion in chronic HBV infection resulted in acute ALT atitis. 2s A substantial number of HCV and HBV coinfec- elevation with precipitous decline in serum HBsAg titions in HBsAg-positive fulminant hepatitis have also ter. 27 A 4 to 6 times reduction in HBV DNA polymerase
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to support the concept that HCV superinfection exerts a viral interference effect that can suppress or terminate the chronic HBsAg carrier state. Our longitudinal No. Anti-HCV Geographic of follow-up study in a large series of patients 56 further Area Year F i r s t Author Cases No. % Reference indicates that the annual incidence ofHBsAg seroclearAsian Pacific ance was 0.43% in patients with HBV infection alone region and 0.64% in patients with HBV and HDV dual infecChina 1994 Tao QM 1345 119 9 32 tion, but it increased strikingly to 2.08% in patients 1994 Panigrahi AK 91 11 12 33 India with HCV and HBV dual infection and 2.33% in pa1994 Sato S 86 16 19 34 Japan tients with HCV, HBV, and HDV triple infection (P 1994 Ohkawa K 156 20 13 35 1993 Kim BS 185 16 9 36 Korea < .0001 for linear trend). These findings and the multiTaiwan 1993 Chung WL 227 23 10 37 variate analysis of the follow-up study point to the HCV 1994 Liaw YF 1498 173 12 38 as the sole hepatotropic virus accountable for enhanced 194" 19" 10" HBsAg seroclearance in chronic HBV infection. 5~ Given Western Country the observations that patients with dual infections m a y Italy 1990 Gaeta GB 54 10 19 39 clear their serum HBsAg, these patients might have 1991 Fattovich G 184 27 15 31 been classified as HCV infection alone in cross-sec28* 9* 32* tional or case control studies, thus the prevalence of Spain 1990 S6_nchez-Tapias JM 156 24 15 40 dual infections with HCV and HBV could have been 1992 Riezu-Boj JI 48 44 30 41 1994 Crespo J 132 17 13 42 underestimated. UK 1992 Brown J 26 6 23 43 Usurpation of HBV by HCV as the Agent in ContinuUSA 1991 Fong TL 148 16 11 44 ing Chronic Hepatitis. Serum ALT levels usually re1992 Jeffers LJ 59 10 17 45 turned to normal after HBsAg seroclearance in pa1992 Ackerman Z 46* 10" 22* 46 USSR 1992 Favorov MO 76 15 20 47 tients with chronic HBV infection, including those 101" 9* 9* associated with HCV superinfection. ~ However, abnormal ALT and hepatitis activity m a y persist in some * Series seropositive for antibodies against hepatitis delta virus. patients. O u r recent clinicopathological and molecular biological study in such patients has provided the eviactivity in HBV carrier chimpanzees was also observed dence to suggest that HCV superinfection may not only after the NANB (HCV) infection. 28 All these studies have terminated chronic HBsAg antigenemia but may illustrate that NANB (HCV) superinfection exerts a also have taken over the role of HBV in causing continsuppressive or inhibitory effect on the replication of uing chronic hepatitis. ~8 the preexisting HBV. Clinical studies in patients with Effect of HBV on HCV Replication. Interestingly, a chronic HBV infection have also shown that anti-HCV reciprocal suppression of HCV replication by HBV repositive patients generally have a low HBV DNA polym- sulting in a state of latent HCV infection has been erase activity34'44 or weak HBV DNA positivity. 31'4°'42'49-52 noted in patients with dual infection. ~4'50'52 A recent In fact, gradual loss ofHBV DN/L with subsequent HBeAg study in h u m a n immunodeficiency virus patients seroconversion and even HBsAg clearance, has been ob- showed that HBV m a y have taken advantage of the served in acute HCV superinfection. 29'52'~3 severe immunodeficiency state and suppressed effecA recent study on patients with HCV and HBV dual tively the HCV expression. 57 In our own study, we have infection has shown that HCV RNA-positive patients also observed patients showing alternating appearance rarely had detectable IgA anti-HBc, suggesting a de- of serum HBV DNA or HCV RNA with concomitant crease of active immune response against HBV. 34 Fur- disappearance of the other virus (Fig. 1). thermore, an immunological study assessing proliferaAggravation of Disease by HCV. Paradoxically, HCV tive response of peripheral blood mononuclear cells to superinfection can cause a much more severe liver disviral antigens showed that such patients responded ease in patients with chronic HBV infection. In terms primarily to HCV antigens. 54 It is interesting to note of conventional liver biochemical tests and the clinical that in one patient, who was seropositive for both HBV presentation, an acute HCV superinfection in preDNA and HCV RNA, retained a low response to HBV viously unrecognized asymptomatic HBsAg carriers is antigens initially, b u t lost the response completely 3 not more severe than when it occurs in non-HBV pamonths later. Concurrently, the cellular response had tients. However, the former group of patients tends to increased toward multiple HCV antigenic compo- have higher serum alphafetoprotein level, which m a y nents. 54 These observations all suggest that HCV pre- reflect more extensive hepatic necrosis 5s than the latvails in causing liver damage, and it has a suppressive ter. In fact, acute HCV superinfection in HBsAg carrieffect on HBV in humans. ers may be the major cause of fulminant/subfulminant A recent case control study showed that patients hepatitis as reported in India. 24 Two independent studwith chronic HBV infection, who cleared serum HBsAg, ies from Taiwan have also shown that a significant had a significantly higher prevalence of anti-HCV than proportion (10% to 20%) of fulminant/subfulminant their age/gender matched controls (31.4% vs. 5.9%, P hepatitis in chronic HBsAg carriers could be attributed < .001). 55 The observation provides indirect evidence to HCV superinfection. ~9'6° These studies lend support TABLE 1. P r e v a l e n c e o f S e r u m A n t i - H C V i n H B s A g - P o s i t i v e
Patients With Chronic Liver Disease
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HEPATOLOGY October 1995 +
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FIG. 1. Clinical course of a patient with dual infection. Note the a l t e r n a t i n g positivity of serum HBV DNA and HCV RNA along the fluctuation of serum ALT activity, even after the resection of HCC. Arrows indicate the time of liver biopsy or the resection. LH, lobular hepatitis.
to the suggestion that HCV superinfection on HBV carriers may enhance the risk of fulminant hepatitisY Besides such catastrophic effect of acute HCV superinfection, liver disease appears to be more severe in terms of histology and clinical decompensation in patients seropositive for both HBsAg and anti-HCV than in patients seropositive for HBsAg alone 42'44'61 or HCV alone. 6~'62This has been well documented in renal allograft recipients who have HCV and HBV dual infection. 63 Progressive liver failure is frequent in severely immunodeficient patients who are infected with human immunodeficiency virus with both HBV and HCV v i r e m i a F Furthermore, case control studies have indicated that dual infection with HCV and HBV has a much higher relative risk for the development of HCC. 64-67 A prospective follow-up study in Italy suggested that dual HBsAg and anti-HCV positivity in patients with cirrhosis is an independent and significant determinant for the development of HCC. 68 Several studies on HBsAg-negative patients with HCC have indeed shown that a significant number of patients seropositive for anti-HCV have both HBV and HCV genomic sequences in tumorous and nontumorous l i v e r t i s s u e . 697z These findings provide the evidence implicating the importance of persistent dual infection with HCV and HBV in hepatocarcinogenesis. Without the molecular studies, such cases in the case-controlled studies could have been considered as HCV-related, and the relative role of dual infection with HCV and HBV in the development of HCC might have been consequently underestimated. H B V S U P E R I N F E C T I O N IN CHRONIC HCV I N F E C T I O N
As mentioned earlier, animal studies showed that preexisting chronic NANB (HCV) infection interfered
with acute HBV as well as HAV infections, by delaying the onset of infections with minimal disease or aborting the infections completely. 17'27 However, this phenomenon of interference was not obvious in patients of the Copenhagen study, because 22 of 69 patients who developed typical acute hepatitis B had evidence of antecedent or past HCV infection. 22 To the best of the author's knowledge, acute HBV infection during followup course of patients with chronic HCV infection has not been reported. Although the data are limited, the Copenhagen study 22 showed none of the 22 patients with acute HBV superinfection and 5% of the 41 patients with acute hepatitis B alone became chronic HBsAg carriers. This seems to implicate that preexisting HCV infection m a y have enhanced the elimination of HBV. However, this interpretation needs to be substantiated by following up more cases for a longer period of time. Whether HBV superinfection may suppress the existing chronic HCV infection also needs further clarification. Of note is that 2 of 10 Taiwanese patients with fulminant/subfulminant hepatitis were observed to be seropositive for IgM anti-HBc as well as anti-HCV of high OD during acute phase, suggesting HBV superinfection in a preexisting chronic HCV infection. 59'6° Similar to the question arising from HCV superinfection in preexisting HBV infection, one may ask whether HBV superinfection may also aggravate the disease severity and increase the risk of fulminant hepatitis. TRIPLE I N F E C T I O N WITH HBV, H C V A N D H D V
Several seroprevalence studies have shown that triple infections with HBV, HCV, and HDV are not rare. The prevalence of serum anti-HCV in patients with HDV infection ranged between 9% to 32%, or around 10% in studies involving more than 100 patients, 31'46'47'52'72 a s shown in Table 1. Clinical studies have sufficiently established the fact that there are patients with acute HBV, HCV, and HDV coinfection, or acute HBV and HDV cosuperinfection in preexisting chronic HCV infection. 22 As expected, acute HDV superinfection can occur in preexisting dual infection with HCV and HBV. Likewise, acute HCV and HDV cosuperinfection is seen in preexisting chronic HBV infection. 72 Successive or sequential HCV and HDV superinfections in patients with chronic HBV infection are also observed in our liver unit. Acute HCV superinfection in previously unrecognized asymptomatic HBsAg carriers with HDV markers (acute or chronic) presents much more severe liver injury than in those without the HDV markers. For instance, 5 of the 9 HDV-positive patients developed hepatic decompensation as compared with 3 of the 27 patients without the HDV marker (Chien RN, et al, Unpublished observations, May 1995). Acute HCV and HDV cosuperinfection as the cause of fulminant/subfulminant hepatitis in previously unrecognized HBsAg carriers is well documented. 59'6° HCV markers were detected in 4 (36%) of the 11 HDV-related fulminant/subfulminant hepatitis s° as compared with 20% of a con-
HEPATOLOGYVol. 22, No. 4, 1995
HBV-DNA HCV-RNA HDV-RNA
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YUN-FAN LIAW
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80
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Months of Follow-up FIG. 2. Clinical course of a patient with triple infection. Note the changes of HBV DNA, HCV RNA, and HDV RNA. These changes continue while the ALT abnormalities remained at borderline level. The broken line represents the lost to follow-up period.
secutive series of 100 patients with acute HDV superinfection observed in the same unit. v3 In the Greek study, the parenteral drug abusers showing fulminant/subfulminant hepatitis were exclusively those having triple viral infection. TM These findings indicate that triple viral infection increases the risk of severe hepatitis. Although it is known that HDV m a y suppress HBV, s the longitudinal follow-up study conducted in our unit showed that HDV superinfection alone did not increase the HBsAg clearance rate. 7~ Furthermore, cosuperinfection with HDV and HCV had no greater suppressive effect than that of HCV superinfection alone in terminating the chronic HBsAg carrier state. 56 In addition, HCV infection m a y somehow influence the replication of HDV as the serum marker(s) for HDV replication, i.e., HDV RNA and IgM anti-HDV, were generally undetectable in patients seropositive for both anti-HDV and anti-HCV. 39'47 Further evidence that HCV tends to suppress HDV comes from immunohistologic findings that HDAg was detected much less frequently in patients coinfected with HCV. 61'72'78 Could HDV exert a suppressive effect on HCV? This is possible, as evidenced by the findings of coexistence or alternating appearance of HDV RNA and HCV RNA, 7~ as shown in Figure 2, and that HCV RNA was frequently absent in the serum and liver in patients seropositive for both anti-HDV and anti-HCV. 52 The finding that no anti-HCV seropositivity was detectable in patients with active HDV replication 47 is also consistent with the concept that HDV m a y suppress HCV. VIRAL I N T E R F E R E N C E Evidence from both animal experiments and h u m a n clinical studies clearly indicates that chronic HBV infection with HCV coinfection or superinfection are asso-
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ciated with viral interference. 6'1t''7'lg'27,2s The precise mechanism is unknown. Possible alterations in the mechanism(s) responsible for virus absorption, penetration and/or replication have been suggested. 27 Possible induction of interferon (IFN), IFN-like substance, or other soluble mediator(s) were also considered. 26'27 However, IFN was not detected in the serial serum samples in NANB (HCV) infection in chimpanzees, iv Cytokines, including tumor necrosis factor alpha and interleukin 6 may also be the candidates, as they may activate certain intracellular pathways that can negatively regulate the HBV expression as shown in a transgenic mouse model. 76 Interestingly, the hepatocyte-derived tumor necrosis factor alpha may exert its actions leading to cytotoxic effect to the same cell that produces it, as well as to the neighboring cells. 77 Because the subcellular localization of HBV core protein can be regulated by the cell cycle, 78 it is possible that HCV induced liver injury and the accompanying cell renewal may increase the expression of HBV epitopes on the hepatocyte surface. This m a y lead to cytotoxic T-cell effected elimination of HBV infected hepatocytes, thus lowering the HBV levels in liver and blood. A recent cotransfection study in a h u m a n hepatoma cell line showed that HCV suppresses the HBV replication involving the process of transcription and encapsidation of HBV pregenomic RNA. This suppressive effect m a y be mediated by the HCV core protein which can also function as a gene-regulatory protein. 79 In essence, many of the variabilities encountered in HCV-associated multiple virus infection can not be explained by a simple answer. The information gathered so far implicates complex interplay o f h u m o r a l and cellular immune network, as well as the virus specific replicating process. A N T M R A L THERAPY IN PATIENTS WITH HCV AND HBV DUAL INFECTIONS
IFN Alfa is currently the most effective antiviral agent that has been used world-wide in the treatment of chronic HBV or HCV infection. However, little is known about the effect of IFN in patients seropositive for both HBsAg and anti-HCV. It has been suggested that a specific dose and duration of IFN regimen for the treatment of either HBV or HCV should be chosen based on which viral infection is determined to be active. so However, a preliminary analysis showed that 15 patients enrolled in our IFN trials in chronic HBV infection were found to have dual infection with HBV and HCV by retrospective HCV assays, and only I of them cleared HBeAg and HBV DNA. The response rate is very low as compared with the overall rate in patients with chronic HBV infection sl or HCV infection. 82 Similar observations have been noted by others in patients having dual infection with HCV and HBV 3t's3 or triple infection with HCV, HDV, and HBV. s3 This is analogous to the therapeutic effect of IFN in HBV patients with HDV superinfection. Of note is that recombinant IFN therapy in a patient seropositive for HBsAg, anti-HCV, and HCV RNA had resulted in a
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seroclearance of HCV RNA, but the HBV hepatitis reactivated, s4 Conversely, lymphoblastoid IFN therapy in one of our patients seropositive for HBeAg, HBV DNA, and anti-HCV resulted in seroclearance of HBV DNA, but this was followed by emergence o f H C V RNA accompanying icteric hepatitis (Liaw YF, et al, Unpublished observation, May 1995). It appears that the interactions between HCV and HBV could influence the effect of IFN therapy in such patients. C O N C L U S I O N S A N D OUTLOOK
This review concludes that the reported worldwide prevalence of serum anti-HCV in patients with chronic HBV or HDV infection is greater than 10%. Dual infection with HCV and HBV, or triple infection with HCV, HBV, and HDV tends to aggravate the severity and progression of the liver disease that appears to be resistant to antiviral therapy. On the other hand, the more recent virus infection tends to suppress the preexisting virus(es). In terms of suppressive effect, HCV seems to be the "strongest" virus, because it has been shown to influence the rate of HBsAg clearance, to suppress HDV, and even to usurp the role of HBV to cause continuing chronic hepatitis. It seems clear that serum HCV markers, at least anti-HCV, should be tested in all patients with chronic HBV and HDV infection, particularly those who develop acute hepatitislike episode, or those who undergo spontaneous HBsAg clearance. For patients having dual or triple infection with HCV, HBsAg clearance can be expected if follow-up HBsAg assay showed a decreasing serum to negative control count ratio. To the contrary, more active and progressive liver disease will follow if coreplication is evident, as indicated by simultaneous presence of nucleic acids of these viruses. At present, antiviral therapy outside of clinical trial is not recommended for such patients with concurrent infections until more information is available to suggest otherwise. The understanding of the mechanisms by which hepatotropic viruses interact is also very much incomplete. Several important issues remain to be answered: (1) what are the viral factors, such as genotype/strain and concentration of each virus, that m a y determine the impact of HCV on the outcome of dual or triple hepatitis virus infection? (2) what are the molecular mechanism(s) regulating these changes? and (3) what are the immune responses of the host and other host factor(s) that may be involved in dual or triple virus infection? It is hoped that future research will clarify these issues and, in particular, the molecular mechanism(s) of the suppressive effect of HCV on HBV or HDV. Such knowledge may help in designing new therapeutic approach in the treatment of chronic HBV and HDV infections. Acknowledgments: The author thanks MH Tsai for excellent secretarial assistance. REFERENCES
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HEPATOLOGYOctober 1995 74. Tassopoulos NC, Koutelou MG, Papatheodoridis GV, Kalantzakis YS, Hatzakis AE. Acute delta hepatitis in Greek parenteral drug abusers. Prog Clin Biol Res 1993;382:221-227. 75. Liaw YF, Sheen IS, Chen TJ, Chu CM, Pao CC. Incidence, determinants and significance of delayed clearance of serum HBsAg in chronic hepatitis B virus infection: a prospective study. HEPATOLOGY1991; 13:627-631. 76. Gilles PN, Fey G, Chisari FV. Tumor necrosis factor alpha negatively regulates hepatitis B virus gene expression in transgenic mice. J Virol 1992;66:3955-3960. 77. Gonz~lez-Amaro R, Garcia-MonzSn C, Garcia-Buey L, MorenoOtero R, Alonso JL, Yagiie E, Pivel JP, et al. Induction of tumor necrosis factor a production by human hepatocytes in chronic viral hepatitis. J Exp Med 1994; 179:841-848. 78. Yeh CT, Wong SW, Fung YK, Ou JH. Cell cycle regulation of nuclear localization of hepatitis B virus core protein. Proc Natl Acad U S A 1993;90:6459-6463. 79. Shih CM, Lo SJ, Miyamura T, Chen SY, Wu Lee YH. Suppression of hepatitis B virus expression and replication by hepatitis C virus core protein in Huh-7 cells. J Virol 1993;5823-5832. 80. Martin P. Hepatitis C infection in patients with chronic hepatitis B: curiosity or cofactor? Am J Gastroenterol 1994; 89:1139-1141. 81. Liaw YF, Lin SM, Chen TJ, Chien RN, Sheen IS, Chu CM. Beneficial effect of prednisolone withdrawal followed by human lymphoblastoid interferon on the treatment of chronic type B hepatitis in Asians: A randomized controlled trial. J Hepatol 1994;20:175-180. 82. Liaw YF, Sheen IS, Lin SM, Chen TJ, Chu CM. Effects ofprednisolone pretreatment in interferon alfa therapy for patients with chronic non-A, non-B (C) hepatitis. Liver 1993; 13:46-50. 83. Weltman WD, Brotodihardjo A, Crewe EB, Farrell GC, Bilous M, Grierson JM, Liddle C. Coinfection with hepatitis B and C or B, C and D viruses results in severe chronic liver disease and responds poorly to interferon-a treatment. J Virol Hep 1995;2:39-45. 84. Villa E, Grottola A, Trande P, Seium Y, Rebecchi AM, Dugani A, Manenti F. Reactivation of hepatitis B virus infection induced by interferon in HBsAg-positive, anti-HCV positive patients. [Letter]. Lancet 1993;341:1413.
Hepatitis B virus (HBV), hepatitis C virus (HCV), a n d hepatitis delta virus (HDV) s h a r e s a m e t r a n s m i s s i o n routes, t h u s dual or triple i n f e c t i o n m a y o c c u r a n d e v e n persist in the s a m e patients. A significant a m o u n t o f lite r a t u r e h a s a c c u m u l a t e d since t h e a d v e n t o f HCV assays. It is p e r t i n e n t to r e v i e w a n d e v a l u a t e t h e clinical a n d virological significance o f HCV in multiple h e p a t o t r o p i c viral infection. The r e p o r t e d series o n s e r o p r e v a l e n c e o f HCV i n d i c a t e that HCV is f o u n d in m o r e t h a n 10% o f HBV- o r HDV-infected patients w o r l d w i d e . Of the patients w i t h dual or triple i n f e c t i o n i n v o l v i n g HCV, t h o s e h a v i n g c o r e p l i c a t i o n o f v i r u s e s t e n d to h a v e s e v e r e a n d p r o g r e s s i v e liver disease that is resistant to i n t e r f e r o n therapy, in c o n t r a s t w i t h p a t i e n t s h a v i n g a single virus infection. Paradoxically, dual or triple hepatitis virus i n f e c t i o n s are a s s o c i a t e d w i t h viral interference. In particular, HCV exerts a s u p p r e s s i v e effect o n H B V a n d HDV and may enhance seroclearance of HBV antigens or e v e n u s u r p t h e role of p r e e x i s t i n g virus as t h e a g e n t for c o n t i n u i n g hepatitis. A l t h o u g h H B V a n d H D V m a y also s u p p r e s s HCV, it appears to be less effective. T h e s e findings clearly s u g g e s t t h e n e c e s s i t y o f m o n i t o r i n g patients w i t h H B V or H D V infectious. In v i e w o f c o m p l e x d y n a m i s m o f viral i n t e r a c t i o n in multiple h e p a t o t r o p i c virus infection, t h e i m p o r t a n c e o f HCV a s s a y in t h e clinical studies c a n n o t be o v e r e m p h a s i z e d . The basic m e c h a n i s m s that r e g u l a t e t h e viral interactions, in particular t h e i m p a c t o f HCV in dual or triple virus infectious, rem a i n to be investigated. (I-IEPATOLOGY1995;22:1101-1108.)
The cloning and sequencing of hepatitis C virus (HCV) have led to the development of serological tests for this virus. 1'2 Recent studies using these serological assays have confirmed that HCV is transmitted pri-
Abbreviations: HCV, hepatitis C virus; HBV, hepatitis B virus; HDV, hepatitis delta virus; HAV, hepatitis A virus; HBsAg, Hepatitis B surface antigen; NANB, non-A, non-B hepatitis virus; ALT, alanine transaminase; anti-HCV, antibodies against HCV; IgM, immunoglobulin M; OD, optical density; HCC, hepatocellular carcinoma; HBeAg, hepatitis Be antigen; IFN, interferon. From the Liver Research Unit, Chang Gung Memorial Hospital, Chang Gung Medical College, Taipei, Taiwan. Received February 21, 1995; accepted June 16, 1995. The work was supported in part by a grant from National Science Council (NSC84-2331-B-182-005 MH) and a grant from Prosperous Foundation, Taipei, Taiwan. Address reprint requests to: Yun-Fan Liaw, MD, Liver Research Unit, Chang Gung Memorial Hospital, 199, Tung Hwa North Road, Taipei 105, Taiwan. Copyright © 1995 by the American Association for the Study of Liver Diseases. 0270-9139/95/2204-001253.00/0
marily via parenteral routes similar to that of hepatitis B virus (HBV) and hepatitis delta virus (HDV), such as blood transfusion, parenteral drug abuse, and hemodialysis. 3-~ Other inapparent percutaneous or mucosal routes m a y also occur. Although HCV does not transmit as efficiently as HBV and HDV, those at risk for HBV or HDV infection are also at risk for HCV infection, and simultaneous or coinfections are possible. One such example is an intensive care nurse, who developed simultaneously infections of hepatitis non-A, non-B, and B viruses. 6 Because these viral infections m a y persist to cause chronic hepatitis or chronic carrier state, 7-9 superinfection of a new virus may occur and persist in patients who have been chronically infected with others. Earlier studies employing less sophisticated tests for hepatitis markers have already shown sequential or simultaneous acute infections by two or even four hepatitis agents. 8'1°'12 Acute hepatitis A virus (HAV) superinfection in chronic hepatitis B surface antigen (HBsAg) carriers was also well noted. ~3'~4HDV coinfection and superinfection in patients with HBV infection is well known since the wide use of HDV assays, s NonA, non-B hepatitis virus (NANB) superinfections have long been suspected to play a significant role in acute exacerbations during the course of chronic HBV infection, 15 or accounted for acute hepatitis in previously unrecognized HBsAg carriers. ~6 The advent of HCV assays has enabled investigators to examine the issues of HCV coinfection or superinfection more precisely. Several investigators have recently shown that dual or triple infection involving HCV is not uncommon. There is emerging evidence to suggest that HCV has significant clinical or virological implications in multiple hepatotropic virus infections, which is the objective of this review. COINFECTION WITH HBV AND H C V Simultaneous Acute Infections With NANB and HBV. In a study on the efficacy of a procedure for HBV
inactivation, Brotman et a117 showed that all 19 chimpanzees exposed to HBV alone developed HBsAg antigenemia within 4 to 9 weeks after the inoculation. Fifteen animals showed alanine transaminase (ALT) elevation with a peak level of 138 to 282 U/L (normal < 26). In contrast, of the 7 chimpanzees inoculated with NANB and HBV simultaneously, only 3 animals
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showed borderline ALT abnormalities and 5 developed been observed in India 24 and France. 2~ With respect HBsAg antigenemia. The onset of antigenemia was sig- to the earlier outbreak in Edinburgh, 19 the sera were nificantly delayed and the duration of antigenemia or retested for HCV RNA in as many cases as feasible. It clinical illness was shorter. They concluded that con- was found that there was significant disproportion of current NANB infection had probably interfered with HCV and HBV dual infection in patients with severe HBV replication and accounted for the delay and ame- or fatal illness, as compared with those who had moderlioration of clinical appearance of disease related to ate or mild/inapparent infection (Marmion BP, perHBV infection. A similar study by Hollinger et al is also sonal communication, 1994). Thus, coinfection with showed that simultaneous NANB infection interfered HCV and HBV can significantly increase the risk of with the development of HBV infection, either by de- fulminant hepatitis. Whether this is because of addilaying its onset or completely aborting it. tive effect of the hepatocyte damage by two concurrent In humans, simultaneous acute infections with viral infections or other unknown mechanisms requires NANB and HBV were first described in an intensive further study. Interestingly, the interaction between care unit nurse who needle-sticked her finger during HCV and HBV is similar to the obligatory interaction venipuncture of an HBsAg-positive uremic patient on between HDV and HBV in that the dual infection m a y chronic hemodialysis. Her clinical and serological cause a much more severe disease and m a y also result changes after the needle stick were characterized by in suppression of HBV replication. 28 late onset of an attenuated B hepatitis, that was preHCV S U P E R I N F E C T I O N IN CHRONIC ceded by an earlier onset of NANB hepatitis, sugHBV INFECTION gesting viral interference. 6 Besides this single case report, an outbreak of exceptionally severe hepatitis in Unless the onset of HBV and/or HCV infections was hemodialysis units was encountered in two Edinburgh clearly known and delineated serologically, such as in hospitals during 1969 to 1970.19 Dual infection with the setting of experimental superinfection in chimpanboth NANB and HBV was suspected. zees 27'2s or in the prospective follow-up study of paSimultaneous Acute Infections With HCV a n d tients with chronic hepatitis virus infections, 29 one can HBV. The stored serum specimens obtained during the hardly tell which virus comes first. The chronological chronic phase of the particular patients described sequences of seropositivity for HBsAg and anti-HCV above 6 were recently assayed for antibodies against can be prospectively documented in some patients, HCV (anti-HCV), and it was positive. Although acute such as hemophiliacs, parenteral drug abusers, and phase serum specimens of this patient were not avail- those on maintenance hemodialysis. 35'3°'31 In the case able to substantiate de n o v o seroconversion of anti- of clinical acute hepatitis, de n o v o seroconversion of HCV and immunoglobulin M antibody to hepatitis B anti-HCV in HBsAg-positive but IgM anti-HBc-negacore antigen (IgM anti-HBc), it is likely that she had tire patient indicates an acute HCV superinfection on acquired acute HCV and HBV coinfection, with ensuing chronic HBV state. 3'16'22 Presence of serum anti-HCV development of chronic hepatitis C. HBV and HCV with low enzyme immunoassay optical density (OD) coinfection is by no means rare. At least seven patients ratio in such patients also indicates acute HCV superwith concurrent posttransfusion acute HCV and HBV infection, if the OD ratios are increasing in the followinfection have been reported recently. 2°'21 In addition, up assays. In contrast, acute HBV superinfection in Krogsgaard et a122 re-evaluated their Copenhagen pa- patients with preceding or past HCV infection can be tients with acute hepatitis B observed during the years suggested by the presence of IgM anti-HBc as well as 1980 to 1982. They found that 3 (4.3%) of the 69 pa- anti-HCV of high OD ratio in the acute phase serum tients had acute HCV coinfection, and another 1 had samples. 22 HBV, HCV, and HDV triple coinfection by detecting de Seroprevalence studies in patients with HBsAg posin o v o anti-HCV seroconversion. Our recent study also tive chronic hepatitis, cirrhosis and hepatocellular carcishowed that around 10% of our patients with acute noma (HCC) have shown that dual infection with HBV hepatitis B were coinfected with HCV. The incidence and HCV is not uncommon in Asia, 32-38 as well as in of HCV may vary notably in different geographic areas. Western countries. 31'39-47 The prevalence is around 10% Similar to the findings of chimpanzee studies,~7'~s pa- to 15% in patients with chronic HBV infection, although tients with acute HBV and HCV coinfection generally it may vary from country to country. This is possibly have a delay in the appearance of HBsAg with short- because of different assay methods used 4s and the size of ened duration of HBsAg antigenemia, and a lower level the studies. The prevalence tends to be higher in studies of HBsAg and ALT as compared with patients with involving less than 100 patients (Table 1). The majority acute HBV infection alone. 2~ These observations sug- of patients with dual or triple infections are hepatitis B e gest that HCV coinfection interferes with HBV and at- antigen (HBeAg)-negative orantibodies against HBeAg tenuates its clinical presentation. However, we have (anti-HBe)-positive. 31 '34 .35. .43 . 49 50 also documented a serologically and virologically Suppression of HBV by HCV. Earlier studies in chimproven case of acute HCV and HBV coinfection pre- panzees showed that acute NANB (HCV) superinfecsenting as biphasic ALT elevation with fulminant hep- tion in chronic HBV infection resulted in acute ALT atitis. 2s A substantial number of HCV and HBV coinfec- elevation with precipitous decline in serum HBsAg titions in HBsAg-positive fulminant hepatitis have also ter. 27 A 4 to 6 times reduction in HBV DNA polymerase
HEPATOLOGY Vol. 22, No. 4, 1995
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to support the concept that HCV superinfection exerts a viral interference effect that can suppress or terminate the chronic HBsAg carrier state. Our longitudinal No. Anti-HCV Geographic of follow-up study in a large series of patients 56 further Area Year F i r s t Author Cases No. % Reference indicates that the annual incidence ofHBsAg seroclearAsian Pacific ance was 0.43% in patients with HBV infection alone region and 0.64% in patients with HBV and HDV dual infecChina 1994 Tao QM 1345 119 9 32 tion, but it increased strikingly to 2.08% in patients 1994 Panigrahi AK 91 11 12 33 India with HCV and HBV dual infection and 2.33% in pa1994 Sato S 86 16 19 34 Japan tients with HCV, HBV, and HDV triple infection (P 1994 Ohkawa K 156 20 13 35 1993 Kim BS 185 16 9 36 Korea < .0001 for linear trend). These findings and the multiTaiwan 1993 Chung WL 227 23 10 37 variate analysis of the follow-up study point to the HCV 1994 Liaw YF 1498 173 12 38 as the sole hepatotropic virus accountable for enhanced 194" 19" 10" HBsAg seroclearance in chronic HBV infection. 5~ Given Western Country the observations that patients with dual infections m a y Italy 1990 Gaeta GB 54 10 19 39 clear their serum HBsAg, these patients might have 1991 Fattovich G 184 27 15 31 been classified as HCV infection alone in cross-sec28* 9* 32* tional or case control studies, thus the prevalence of Spain 1990 S6_nchez-Tapias JM 156 24 15 40 dual infections with HCV and HBV could have been 1992 Riezu-Boj JI 48 44 30 41 1994 Crespo J 132 17 13 42 underestimated. UK 1992 Brown J 26 6 23 43 Usurpation of HBV by HCV as the Agent in ContinuUSA 1991 Fong TL 148 16 11 44 ing Chronic Hepatitis. Serum ALT levels usually re1992 Jeffers LJ 59 10 17 45 turned to normal after HBsAg seroclearance in pa1992 Ackerman Z 46* 10" 22* 46 USSR 1992 Favorov MO 76 15 20 47 tients with chronic HBV infection, including those 101" 9* 9* associated with HCV superinfection. ~ However, abnormal ALT and hepatitis activity m a y persist in some * Series seropositive for antibodies against hepatitis delta virus. patients. O u r recent clinicopathological and molecular biological study in such patients has provided the eviactivity in HBV carrier chimpanzees was also observed dence to suggest that HCV superinfection may not only after the NANB (HCV) infection. 28 All these studies have terminated chronic HBsAg antigenemia but may illustrate that NANB (HCV) superinfection exerts a also have taken over the role of HBV in causing continsuppressive or inhibitory effect on the replication of uing chronic hepatitis. ~8 the preexisting HBV. Clinical studies in patients with Effect of HBV on HCV Replication. Interestingly, a chronic HBV infection have also shown that anti-HCV reciprocal suppression of HCV replication by HBV repositive patients generally have a low HBV DNA polym- sulting in a state of latent HCV infection has been erase activity34'44 or weak HBV DNA positivity. 31'4°'42'49-52 noted in patients with dual infection. ~4'50'52 A recent In fact, gradual loss ofHBV DN/L with subsequent HBeAg study in h u m a n immunodeficiency virus patients seroconversion and even HBsAg clearance, has been ob- showed that HBV m a y have taken advantage of the served in acute HCV superinfection. 29'52'~3 severe immunodeficiency state and suppressed effecA recent study on patients with HCV and HBV dual tively the HCV expression. 57 In our own study, we have infection has shown that HCV RNA-positive patients also observed patients showing alternating appearance rarely had detectable IgA anti-HBc, suggesting a de- of serum HBV DNA or HCV RNA with concomitant crease of active immune response against HBV. 34 Fur- disappearance of the other virus (Fig. 1). thermore, an immunological study assessing proliferaAggravation of Disease by HCV. Paradoxically, HCV tive response of peripheral blood mononuclear cells to superinfection can cause a much more severe liver disviral antigens showed that such patients responded ease in patients with chronic HBV infection. In terms primarily to HCV antigens. 54 It is interesting to note of conventional liver biochemical tests and the clinical that in one patient, who was seropositive for both HBV presentation, an acute HCV superinfection in preDNA and HCV RNA, retained a low response to HBV viously unrecognized asymptomatic HBsAg carriers is antigens initially, b u t lost the response completely 3 not more severe than when it occurs in non-HBV pamonths later. Concurrently, the cellular response had tients. However, the former group of patients tends to increased toward multiple HCV antigenic compo- have higher serum alphafetoprotein level, which m a y nents. 54 These observations all suggest that HCV pre- reflect more extensive hepatic necrosis 5s than the latvails in causing liver damage, and it has a suppressive ter. In fact, acute HCV superinfection in HBsAg carrieffect on HBV in humans. ers may be the major cause of fulminant/subfulminant A recent case control study showed that patients hepatitis as reported in India. 24 Two independent studwith chronic HBV infection, who cleared serum HBsAg, ies from Taiwan have also shown that a significant had a significantly higher prevalence of anti-HCV than proportion (10% to 20%) of fulminant/subfulminant their age/gender matched controls (31.4% vs. 5.9%, P hepatitis in chronic HBsAg carriers could be attributed < .001). 55 The observation provides indirect evidence to HCV superinfection. ~9'6° These studies lend support TABLE 1. P r e v a l e n c e o f S e r u m A n t i - H C V i n H B s A g - P o s i t i v e
Patients With Chronic Liver Disease
1104
YUN-FAN LIAW
HBV-DNA ++ . . . . HCV-RNA
HEPATOLOGY October 1995 +
+
anti-HBe(+) 800700IntI-HCV(+)
LH
,
0
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.......
, . . . . .
20
.. . . . .
,'
40
,
60
-
,
.
80
"
"
;
100
"
"
120
140
Months of Follow-up
FIG. 1. Clinical course of a patient with dual infection. Note the a l t e r n a t i n g positivity of serum HBV DNA and HCV RNA along the fluctuation of serum ALT activity, even after the resection of HCC. Arrows indicate the time of liver biopsy or the resection. LH, lobular hepatitis.
to the suggestion that HCV superinfection on HBV carriers may enhance the risk of fulminant hepatitisY Besides such catastrophic effect of acute HCV superinfection, liver disease appears to be more severe in terms of histology and clinical decompensation in patients seropositive for both HBsAg and anti-HCV than in patients seropositive for HBsAg alone 42'44'61 or HCV alone. 6~'62This has been well documented in renal allograft recipients who have HCV and HBV dual infection. 63 Progressive liver failure is frequent in severely immunodeficient patients who are infected with human immunodeficiency virus with both HBV and HCV v i r e m i a F Furthermore, case control studies have indicated that dual infection with HCV and HBV has a much higher relative risk for the development of HCC. 64-67 A prospective follow-up study in Italy suggested that dual HBsAg and anti-HCV positivity in patients with cirrhosis is an independent and significant determinant for the development of HCC. 68 Several studies on HBsAg-negative patients with HCC have indeed shown that a significant number of patients seropositive for anti-HCV have both HBV and HCV genomic sequences in tumorous and nontumorous l i v e r t i s s u e . 697z These findings provide the evidence implicating the importance of persistent dual infection with HCV and HBV in hepatocarcinogenesis. Without the molecular studies, such cases in the case-controlled studies could have been considered as HCV-related, and the relative role of dual infection with HCV and HBV in the development of HCC might have been consequently underestimated. H B V S U P E R I N F E C T I O N IN CHRONIC HCV I N F E C T I O N
As mentioned earlier, animal studies showed that preexisting chronic NANB (HCV) infection interfered
with acute HBV as well as HAV infections, by delaying the onset of infections with minimal disease or aborting the infections completely. 17'27 However, this phenomenon of interference was not obvious in patients of the Copenhagen study, because 22 of 69 patients who developed typical acute hepatitis B had evidence of antecedent or past HCV infection. 22 To the best of the author's knowledge, acute HBV infection during followup course of patients with chronic HCV infection has not been reported. Although the data are limited, the Copenhagen study 22 showed none of the 22 patients with acute HBV superinfection and 5% of the 41 patients with acute hepatitis B alone became chronic HBsAg carriers. This seems to implicate that preexisting HCV infection m a y have enhanced the elimination of HBV. However, this interpretation needs to be substantiated by following up more cases for a longer period of time. Whether HBV superinfection may suppress the existing chronic HCV infection also needs further clarification. Of note is that 2 of 10 Taiwanese patients with fulminant/subfulminant hepatitis were observed to be seropositive for IgM anti-HBc as well as anti-HCV of high OD during acute phase, suggesting HBV superinfection in a preexisting chronic HCV infection. 59'6° Similar to the question arising from HCV superinfection in preexisting HBV infection, one may ask whether HBV superinfection may also aggravate the disease severity and increase the risk of fulminant hepatitis. TRIPLE I N F E C T I O N WITH HBV, H C V A N D H D V
Several seroprevalence studies have shown that triple infections with HBV, HCV, and HDV are not rare. The prevalence of serum anti-HCV in patients with HDV infection ranged between 9% to 32%, or around 10% in studies involving more than 100 patients, 31'46'47'52'72 a s shown in Table 1. Clinical studies have sufficiently established the fact that there are patients with acute HBV, HCV, and HDV coinfection, or acute HBV and HDV cosuperinfection in preexisting chronic HCV infection. 22 As expected, acute HDV superinfection can occur in preexisting dual infection with HCV and HBV. Likewise, acute HCV and HDV cosuperinfection is seen in preexisting chronic HBV infection. 72 Successive or sequential HCV and HDV superinfections in patients with chronic HBV infection are also observed in our liver unit. Acute HCV superinfection in previously unrecognized asymptomatic HBsAg carriers with HDV markers (acute or chronic) presents much more severe liver injury than in those without the HDV markers. For instance, 5 of the 9 HDV-positive patients developed hepatic decompensation as compared with 3 of the 27 patients without the HDV marker (Chien RN, et al, Unpublished observations, May 1995). Acute HCV and HDV cosuperinfection as the cause of fulminant/subfulminant hepatitis in previously unrecognized HBsAg carriers is well documented. 59'6° HCV markers were detected in 4 (36%) of the 11 HDV-related fulminant/subfulminant hepatitis s° as compared with 20% of a con-
HEPATOLOGYVol. 22, No. 4, 1995
HBV-DNA HCV-RNA HDV-RNA
+ +
YUN-FAN LIAW
+ + .~
IgM a n t i - H D V
+
+
+ +
anti-HBe(+) 1600,
antI-HCV(+)
40C 300~ 200 t 1004~
1.:. 0 !::":!'
,
•:.....~:.~..:.:..;.:..:.\'-~:.-..:/.~'/.~.:.:.:~:<.~'/...:.:?.~/.~.:~.~i:::.:::..:.~..~:::.. ~:~:,,...:.~?..~..:.-.:<~.~,, ~.....~.:~.:.....~.~ -.:.... 20
40
60
80
100
120
Months of Follow-up FIG. 2. Clinical course of a patient with triple infection. Note the changes of HBV DNA, HCV RNA, and HDV RNA. These changes continue while the ALT abnormalities remained at borderline level. The broken line represents the lost to follow-up period.
secutive series of 100 patients with acute HDV superinfection observed in the same unit. v3 In the Greek study, the parenteral drug abusers showing fulminant/subfulminant hepatitis were exclusively those having triple viral infection. TM These findings indicate that triple viral infection increases the risk of severe hepatitis. Although it is known that HDV m a y suppress HBV, s the longitudinal follow-up study conducted in our unit showed that HDV superinfection alone did not increase the HBsAg clearance rate. 7~ Furthermore, cosuperinfection with HDV and HCV had no greater suppressive effect than that of HCV superinfection alone in terminating the chronic HBsAg carrier state. 56 In addition, HCV infection m a y somehow influence the replication of HDV as the serum marker(s) for HDV replication, i.e., HDV RNA and IgM anti-HDV, were generally undetectable in patients seropositive for both anti-HDV and anti-HCV. 39'47 Further evidence that HCV tends to suppress HDV comes from immunohistologic findings that HDAg was detected much less frequently in patients coinfected with HCV. 61'72'78 Could HDV exert a suppressive effect on HCV? This is possible, as evidenced by the findings of coexistence or alternating appearance of HDV RNA and HCV RNA, 7~ as shown in Figure 2, and that HCV RNA was frequently absent in the serum and liver in patients seropositive for both anti-HDV and anti-HCV. 52 The finding that no anti-HCV seropositivity was detectable in patients with active HDV replication 47 is also consistent with the concept that HDV m a y suppress HCV. VIRAL I N T E R F E R E N C E Evidence from both animal experiments and h u m a n clinical studies clearly indicates that chronic HBV infection with HCV coinfection or superinfection are asso-
1105
ciated with viral interference. 6'1t''7'lg'27,2s The precise mechanism is unknown. Possible alterations in the mechanism(s) responsible for virus absorption, penetration and/or replication have been suggested. 27 Possible induction of interferon (IFN), IFN-like substance, or other soluble mediator(s) were also considered. 26'27 However, IFN was not detected in the serial serum samples in NANB (HCV) infection in chimpanzees, iv Cytokines, including tumor necrosis factor alpha and interleukin 6 may also be the candidates, as they may activate certain intracellular pathways that can negatively regulate the HBV expression as shown in a transgenic mouse model. 76 Interestingly, the hepatocyte-derived tumor necrosis factor alpha may exert its actions leading to cytotoxic effect to the same cell that produces it, as well as to the neighboring cells. 77 Because the subcellular localization of HBV core protein can be regulated by the cell cycle, 78 it is possible that HCV induced liver injury and the accompanying cell renewal may increase the expression of HBV epitopes on the hepatocyte surface. This m a y lead to cytotoxic T-cell effected elimination of HBV infected hepatocytes, thus lowering the HBV levels in liver and blood. A recent cotransfection study in a h u m a n hepatoma cell line showed that HCV suppresses the HBV replication involving the process of transcription and encapsidation of HBV pregenomic RNA. This suppressive effect m a y be mediated by the HCV core protein which can also function as a gene-regulatory protein. 79 In essence, many of the variabilities encountered in HCV-associated multiple virus infection can not be explained by a simple answer. The information gathered so far implicates complex interplay o f h u m o r a l and cellular immune network, as well as the virus specific replicating process. A N T M R A L THERAPY IN PATIENTS WITH HCV AND HBV DUAL INFECTIONS
IFN Alfa is currently the most effective antiviral agent that has been used world-wide in the treatment of chronic HBV or HCV infection. However, little is known about the effect of IFN in patients seropositive for both HBsAg and anti-HCV. It has been suggested that a specific dose and duration of IFN regimen for the treatment of either HBV or HCV should be chosen based on which viral infection is determined to be active. so However, a preliminary analysis showed that 15 patients enrolled in our IFN trials in chronic HBV infection were found to have dual infection with HBV and HCV by retrospective HCV assays, and only I of them cleared HBeAg and HBV DNA. The response rate is very low as compared with the overall rate in patients with chronic HBV infection sl or HCV infection. 82 Similar observations have been noted by others in patients having dual infection with HCV and HBV 3t's3 or triple infection with HCV, HDV, and HBV. s3 This is analogous to the therapeutic effect of IFN in HBV patients with HDV superinfection. Of note is that recombinant IFN therapy in a patient seropositive for HBsAg, anti-HCV, and HCV RNA had resulted in a
1106
YUN-FAN LIAW
seroclearance of HCV RNA, but the HBV hepatitis reactivated, s4 Conversely, lymphoblastoid IFN therapy in one of our patients seropositive for HBeAg, HBV DNA, and anti-HCV resulted in seroclearance of HBV DNA, but this was followed by emergence o f H C V RNA accompanying icteric hepatitis (Liaw YF, et al, Unpublished observation, May 1995). It appears that the interactions between HCV and HBV could influence the effect of IFN therapy in such patients. C O N C L U S I O N S A N D OUTLOOK
This review concludes that the reported worldwide prevalence of serum anti-HCV in patients with chronic HBV or HDV infection is greater than 10%. Dual infection with HCV and HBV, or triple infection with HCV, HBV, and HDV tends to aggravate the severity and progression of the liver disease that appears to be resistant to antiviral therapy. On the other hand, the more recent virus infection tends to suppress the preexisting virus(es). In terms of suppressive effect, HCV seems to be the "strongest" virus, because it has been shown to influence the rate of HBsAg clearance, to suppress HDV, and even to usurp the role of HBV to cause continuing chronic hepatitis. It seems clear that serum HCV markers, at least anti-HCV, should be tested in all patients with chronic HBV and HDV infection, particularly those who develop acute hepatitislike episode, or those who undergo spontaneous HBsAg clearance. For patients having dual or triple infection with HCV, HBsAg clearance can be expected if follow-up HBsAg assay showed a decreasing serum to negative control count ratio. To the contrary, more active and progressive liver disease will follow if coreplication is evident, as indicated by simultaneous presence of nucleic acids of these viruses. At present, antiviral therapy outside of clinical trial is not recommended for such patients with concurrent infections until more information is available to suggest otherwise. The understanding of the mechanisms by which hepatotropic viruses interact is also very much incomplete. Several important issues remain to be answered: (1) what are the viral factors, such as genotype/strain and concentration of each virus, that m a y determine the impact of HCV on the outcome of dual or triple hepatitis virus infection? (2) what are the molecular mechanism(s) regulating these changes? and (3) what are the immune responses of the host and other host factor(s) that may be involved in dual or triple virus infection? It is hoped that future research will clarify these issues and, in particular, the molecular mechanism(s) of the suppressive effect of HCV on HBV or HDV. Such knowledge may help in designing new therapeutic approach in the treatment of chronic HBV and HDV infections. Acknowledgments: The author thanks MH Tsai for excellent secretarial assistance. REFERENCES
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HEPATOLOGYOctober 1995 2. Kuo G, Choo QL, Alter HJ, Gitnick GL, Redeker AG, Purcell RH, Miyamura T, et al. An assay for circulating antibodies to a major etiologic virus of human non-A, non-B hepatitis. Science 1989; 244:362-364. 3. Alter HJ, Purcell RH, Shih WJ, Melpolder JC, Houghton M, Choo QL, Kuo G. Detection of antibody to hepatitis C virus in prospectively followed transfusion recipients with acute and chronic non-A, non-B hepatitis. N Engl J Med 1989;321:14941500. 4. Estaban JI, Estaban R, Viladomiu L, Lopez-Talavera JC, Gonzalez A, Hernandez JM, Roget M, et al. Hepatitis C virus antibodies among risk groups in Spain. Lancet 1989;ii:294-297. 5. Lin HH, Huang CC, Sheen IS, Lin DY, Liaw YF. Prevalence of antibodies to hepatitis C virus in hemodialysis unit. Am J Nephrol 1991; 11:192-194. 6. Liaw YF, Chu CM, ChangChien CS, Wu CS. Simultaneous acute infections with hepatitis non-A, non-B and B viruses. Dig Dis Sci 1982;27:762-764. 7. Liaw YF. Natural history of chronic hepatitis B virus infection. In: Liaw YF, ed. Chronic Hepatitis. Amsterdam: Elsevier, 1986:9-18. 8. Rizzetto M, Bonino F, Verme G. Hepatitis delta virus infection of the liver: progress in virology, pathology, and diagnosis. Semin Liver Dis 1988;8:350-360. 9. Genesca J, Esteban JI, Alter HJ. Blood borne non-A, non-B hepatitis: Hepatitis C. Semin Liver Dis 1991;11:147-164. 10. Mosley JW, Redeker AG, Feinstone SM, Purcell RH. Multiple hepatitis viruses in multiple attacks of acute viral hepatitis. N Engl J Med 1977;296:75-78. 11. Norkrans G, FrSsner G, Hermodsson S, Iwarson S. Multiple hepatitis attacks in drug addicts. JAMA 1980;243:1056-1058. 12. Mathiesen LR, Hardt SF, Nielson JO, Sloth K, Zoffimann H, M~ller AM, Wong D, et al. Epidemiology and clinical characteristics of acute hepatitis types A, B, and non-A, non-B. Scand J Gastroenterol 1979; 14:849-856. 13. Dietzman DE, Mattew EB, Madden DL. The occurrence of epidemic infectious hepatitis in chronic carriers of Australia antigen. J Pediatr 1972;80:577-582. 14. Hindman SH, Maynard JE, Bradley DW, Berguist KR, Denes AE. Simultaneous infection with type A and B hepatitis viruses. Am J Epidemiol 1977;105:135-139. 15. Liaw YF, Tai DI, Chu CM, Pao CC, Chen TJ. Acute exacerbation of chronic type B hepatitis: comparison between HBeAg and antibody-positive patients. HEPATOLOGY1987;7:20-23. 16. Chu CM, Liaw YF, Pao CC, Huang MJ. The etiology of acute hepatitis superimposed upon previously unrecognized HBsAg carriers. HEPATOLOGY1989;9:452-456. 17. Brotman B, Prince AM, Huima T, Richardson L, van den Ende MC, Pfeifer U. Interference between non-A, non-B and hepatitis B virus infection in chimpanzees. J Med Virol 1983; 11:191-205. 18. Hollinger FB, Dolana G, Thomas W, Gyorkey F. Reduction in risk of hepatitis transmission by heat-treatment of a human factor VIII concentrate. J Infect Dis 1984; 150:250-262. 19. Marmion BP, Burrell CJ, Tonkin RW, Dickson J. Dialysis-associated hepatitis in Edinburgh; 1969-1978. Rev Infect Dis 1982;4:619-637. 20. Baginski I, Chemin I, Hantz O, Pichoud C, Jullien AM, Chevre JC, Li JS, et al. Transmission of serologically silent hepatitis B virus along with hepatitis C virus in two cases of posttransfusion hepatitis. Transfusion 1992;32:215-220. 21. Mimms LT, Mosley JW, Hollinger FB, Aach RD, Stevens CE, Cunningham M, Vallari DV, et al. Effect of concurrent acute infection with hepatitis C virus on acute hepatitis B virus infection. Br Med J 1993;307:1095-1097. 22. Krogsgaard K, Wantzin P, Mathisen L, Ring-Larsen H, the Copenhagen hepatitis acuta programme. Chronic evolution of acute hepatitis B: the significance of simultaneous infections with hepatitis C and D. Scand J Gastroenterol 1991;26:275-280. 23. Chu CM, Liaw YF. Simultaneous acute hepatitis B virus and hepatitis C virus infection leading to fulminant hepatitis and subsequent chronic hepatitis C. Clin Infect Dis 1995;20:703-705. 24. Tandon BN, Irshad M, Acharya SK, Joshi YK. Hepatitis C virus
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46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57. 58.
59.
60. 61.
62.
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