Distribution of hepatitis C virus genotypes in the Middle East

International Journal of Infectious Diseases (2006) 10, 272—277

http://intl.elsevierhealth.com/journals/ijid

REVIEW

Distribution of hepatitis C virus genotypes in the Middle East S. Ramia a,*, J. Eid-Fares b a

Department of Medical Laboratory Technology, Faculty of Health Sciences, American University of Beirut, PO Box 11-0236, Riad El-Soloh, 1107—2020, Beirut, Lebanon b Department of Epidemiology and Population Health, Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon Received 11 May 2005; received in revised form 15 July 2005; accepted 21 July 2005 Corresponding Editor: Jane N. Zuckerman, London, UK

KEYWORDS Hepatitis C virus; Genotypes; Middle East; Epidemiology

Summary It is well established that hepatitis C develops into cirrhosis of the liver and hepatocellular carcinoma (HCC) both of which are fatal diseases. The World Health Organization estimates that there are at least 21.3 million hepatitis C virus (HCV) carriers in the Eastern Mediterranean countries, which is close to the number of carriers estimated in the Americas and Europe combined. With such a high disease burden of HCV infection in this part of the world, and in light of the new evidence that genotypes may influence the outcome of antiviral therapy, the focus of this review is on the epidemiology and distribution of HCV genotypes in the Eastern Mediterranean countries. Accumulated data show that there are two main patterns for the distribution of HCV genotypes in the Middle East: in the first pattern, genotype 4 is prevalent in most of the Arab countries, and in the second pattern, genotype 1a or 1b predominates in the nonArab countries. Results from the limited number of clinical trials on the treatment of chronic HCV genotype 4 using peginterferon alfa-2b in combination with ribavirin are encouraging. However, efforts to develop more effective antiviral therapies and the establishment of an effective HCV vaccine remain the largest challenges for the near future. # 2006 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Introduction In 1999, the World Health Organization (WHO) estimated that 170 million individuals were chronically infected with the hepatitis C virus (HCV) worldwide.1 Furthermore, it is now

* Corresponding author. Tel.: +961 1 350000x4698; fax: +961 1 744470. E-mail address: [email protected] (S. Ramia).

well established that hepatitis C develops into cirrhosis of the liver and hepatocellular carcinoma (HCC) both of which are fatal diseases.2—6 These facts clearly indicate that HCV is an important public health problem globally. To date, numerous data have been accumulated on the epidemiology of HCV infection.7,8 Accumulated data show that HCV genotypes vary in their distribution, which may have clinical significance.9—11 The WHO estimates that there are at least 21.3 million HCV carriers in the Eastern Mediterranean countries, which is close to the number of carriers

1201-9712/$32.00 # 2006 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijid.2005.07.008

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Distribution of hepatitis C virus genotypes in the Middle East estimated in the Americas (13.1 million) and Europe (8.9 million) combined.1 Indeed, one of the highest prevalences of HCV infection (18.1%) has been reported from Egypt, a Middle Eastern country.1 With such a high disease burden of HCV infection in this part of the world and in light of the new evidence that genotypes may influence the outcome of antiviral therapy,12—15 the focus of this review is on the epidemiology of HCV infection and distribution of HCV genotypes in the Eastern Mediterranean countries and possible implications for the future. However, since there have been dramatic advances in the diagnosis of HCV infection during the past decade, this article first reviews the molecular organization and the genetic diversity of the HCV genome, and then highlights the significance and reliability of the tests available for testing and confirmation of HCV genotypes.

ment length polymorphism (RFLP) of the PCR amplifications28 and differential hybridization.29 Among these direct methods, genomic amplification and sequencing, followed by sequence comparison and phylogenetic tree construction for confirmation is considered the gold standard. The genomic regions commonly used in this approach include core, E1, NS5 and 50 NC.30 More recently, HCV genotyping has been determined indirectly by testing for type-specific antibodies with a competitive enzyme immunoassay.31 However, although comparative analysis has shown a good overall agreement between serotyping and molecular genetic analysis32 the sensitivity of PCR-based assays over serologic assays has been distinctly higher.31,32

HCV genome

Epidemiology of HCV genotypes

Genomic organization

Worldwide

HCV is an aspheric, enveloped virus classified in the Hepacivirus genus of the Flaviviridai family.16 The viral genome is a single stranded linear RNA of positive sense. The genome is approximately 9.6 kb in size and contains an open reading frame (ORF) flanked by both a 50 and a 30 non-coding region (NC).17 Immediately downstream of the 50 NC is the single ORF, which encodes a large protein polyprotein precursor. This precursor is subsequently cleaved by host and viral proteases into various structural and nonstructural proteins. The structural proteins are at the 50 end and include the capsid or core protein (c), two envelope proteins (E1 and E2) and a small protein of unknown function (P7). The structural proteins are followed by at least six nonstructural (NS) proteins denoted as NS2, NS3, NS4A, NS4B, NS5A, and NS5B.10

The worldwide distribution of HCV genotypes and their subtypes is shown in Table 1. Genotypes 1, 2, and 3 are the most frequently encountered genotypes worldwide.33—35 However, significant differences are noticed when subtype distribution is investigated. In North America and Northern Europe, 1a is the most common subtype followed by 2b and 3a.36,37 The most common subtype in Southern and Eastern Europe is 1b, followed by genotypes 2 and 3.38,39 Although HCV subtypes 2a and 2b are relatively common in North America and Europe, subtype 2c is found commonly in Northern Italy.40 Subtype 3a, which is endemic in South East Asia,34 has been encountered in Europe and the USA, and with relatively high frequency in intravenous drug abusers (IVDA).41,42 This leads to the suggestion that this subtype may have originated from South East Asia and was introduced to Europe and North America by travelers.43 In North Africa, similar to the situation in Eastern and Southern Europe, HCV subtype 1b seems to predominate.44—46 In Tunisia, subtype 1b is largely the dominant subtype (79%) followed by 1a, 2a, 2b, 3a, and 4.43 In Morocco in contrast to Tunisia45,46 subtype 1b, although the most prevalent, had lower prevalences (47—48%) but a higher circulation of genotype 2 (29—37%).46 The pattern in Tunisia is reminiscent of that in Japan where subtype 1b accounts for 73% followed by genotype 2 (20%) and subtype 1a (2%).34 Genotypes other than 1, 2 and 3 are actually more common among HCV-infected people in other parts of the world. Genotype 4 seems to be confined to the Middle East47 and Central Africa,48—50 while HCV genotype 5 has been isolated almost exclusively in South Africa51 where it predominates, followed by genotypes 1, 2, 3, and 4, respectively.51 Genotype 6 has been isolated in Hong Kong, Vietnam and throughout South East Asia.52—54 In one study from Vietnam, genotype 1 was the most common genotype followed by genotypes 6—9 and genotype 2.55 HCV genotypes 7, 8, and 9 have been identified mainly in Vietnamese patients,56 while genotypes 10 and 11 have been reported from Indonesia.57 It has been suggested that genotypes 7—11 are variants of the same group and should be classified as members of genotype 6.16 It is interesting to note that in the Philippines, HCV subtype distribution is similar to that seen in North America and Northern Europe, where subtype 1a is the most common followed by 1b, 2a and 2b.58

Genetic diversity of the HCV genome Although both the 50 and 30 NC of the HCV genome possess highly conserved terminal sequences,18 HCV is characterized by a high degree of genetic heterogeneity19 and as such it is similar to other RNA viruses. The most heterogeneous regions of the genome are the genes encoding the two envelope proteins, E1 and E2. The N terminus of the E2 gene contains the most variable region of the entire genome and has been referred to as the first hypervariable region (HVR1).20 A second hypervariable region, referred to as HVR2, is located just 30 of HVR1.21 This genetic heterogeneity of HCV has been classified into four hierarchical strata: genotypes, subgenotypes (subtypes), isolates, and quasi-species. The degree of nucleotide sequence variation for each stratum (expressed as a percentage) is 30—50%, 15—30%, 5—15%, and 15%, respectively.12,22 A total of eleven major genotypes, designated according to the order of their discovery1—11 have been identified23,24 and more than 90 subtypes have been described. An increasing number of novel subtypes is emerging and more detailed phylogenetic analysis of these isolates is recommended.25,26

Testing for HCV genotypes Many methods have been used for HCV genotyping including genomic amplification and sequencing,27 restriction frag-

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Table 1

Worldwide distribution of hepatitis C virus genotypes and subtypes

Region

Genotype/subtype

References

Most common

Less common

North America

1a

1b, 2b, 3a

36,37

Europe Northern Europe Southern and Eastern Europe

1a 1b

1b, 2, 3a 1a, 2, 3, 2c

36,37

Japan

1b

2a, 2b, 3b

34

Africa North Africa * Tunisia Morocco

1b 1b

1a, 2a, 2b, 3a, 4 2a, 2c, 1a

Central Africa Gabon Nigeria Cameroon

4 1, 4 4

1a, 1b, 2a, 2b 2 1, 2

48

South Africa

5

1, 2, 3 and 4

51

1 7, 8, 9 10, 11 1a

6, 7, 8, 9, 2 10, 11 1a 1b, 2a, 2b

52—55

South East Asia Throughout the region Vietnam, Thailand and Myanmar Indonesia Philippines *

38,39

44 45,46

49 50

56 57 58

Excluding Egypt.

Middle East Distribution of HCV genotypes and subtypes in the Middle East59—76 is shown in Table 2. Surprisingly, the accumulated data show that there are two main patterns for the distribution of HCV genotypes: one is peculiar to the Arab countries (except for Jordan) where genotype 4 predominates, while Table 2 Distribution of hepatitis C virus genotypes and subtypes in the Middle East Region

Arab countries Egypt Gaza Strip Jordan Kuwait Lebanon Saudi Arabia Syria

Genotype/subtype

References

Most common

Less common

4 4 1a 4 4 4 4

1a, 1b, 2a 1, 3a 1b, 4 1 1a, 1b 1a, 1b, 3a 1b,1a

59—61

1b 4

72,73

Non-Arab countries Iran South 1a North West 3a

62 63 64 65,66 67—70 71

Israel

1b

1a, 2

62,74

Turkey

1b

1a

75,76

the other pattern is characteristic of the non-Arab countries (Turkey, Israel, and Iran) where genotype 1 predominates. Although varying prevalences of genotype 4 have been reported from the Arab countries, it is noteworthy that genotype 4 is quasi-exclusive (91%) in Egypt which is also a North African country.59—61 Based on only one known study in Jordan, 1a is the dominant subtype (40%) followed by 1b (33.3%) and genotype 4 (26.6%).63 In Turkey75,76 and in Israel62,74 subtype 1b is the dominant subtype (>70%) followed by 1a, similar to the pattern seen in Eastern and Southern Europe.38,39 Subtype 1a is the most common subtype in Iran followed by 3a, 1b, and 4.72,73 The two different patterns for the distribution of HCV genotypes in the Middle East are evident in the study conducted to determine genotypes of HCV in the Gaza Strip and Southern Israel.62 The Gaza Strip borders the southern part of Israel and Egypt, and a few thousand inhabitants cross the border daily from Gaza to both countries. The most common genotypes found were type 1b (62%) in Southern Israel and type 4 (78%) in the Gaza Strip, corresponding to the most prevalent genotype in Egypt.61 The high similarity between type 4 isolates from Gaza Strip and Egypt was demonstrated by sequence analysis of the HCV 50 NC region.62 Subtype 1b in Israel was followed by subtypes 1a, 2a/2c, and 3a, respectively, and no genotype 4 was found.62 Although genotype 4 is generally uncommon in Western countries, varying prevalences have been reported in Southern Europe.77—79 During the past two years it has become evident that the number of patients infected with HCV genotype 4 in Europe80,81 and the USA,82 and most recently in Southern India,83 is rising. This emerging pattern might reflect changing immigration patterns in those areas.

275

Distribution of hepatitis C virus genotypes in the Middle East

Implications for the future

References

Clinical significance of HCV genotypes

1. World Health Organization. Hepatitis C-global prevalence (update). Wkly Epidemiol Rec 1999;49:425—7. 2. National Institutes of Health Consensus Development Conference Panel Statement. Management of hepatitis C. Hepatology 1997;26:S2—10. 3. Seeff LB. Natural history of viral hepatitis, type C. Semin Gastrointest Dis 1995;6:20—7. 4. Di Bisceglie AM. Hepatitis C and hepatocellular carcinoma. Semin Liver Dis 1995;15:64—9. 5. Kuo G, Choo QL, Alter HJ, Gitnick GL, Redeker AG, Purcell RH, et al. An assay for circulating antibodies to a major etiologic virus of human non-A, non-B hepatitis. Science 1989;244:362— 4. 6. Lauer GM, Walker BD. Hepatitis C virus infection. N Engl J Med 2001;345:41—52. 7. Higuchi M, Tanaka E, Kiyosawa K. Epidemiology and clinical aspects of hepatitis C. Jpn J Infect Dis 2002;55:69—77. 8. Farci P, Purcell R. Clinical significance of hepatitis C virus genotypes and quasispecies. Semin Liver Dis 2000;20:103—26. 9. Mondelli MU, Silini E. Clinical significance of hepatitis C virus genotypes. J Hepatol 1999;31(Suppl. 1):65—70. 10. Al-Faleh F, Ramia S, Hepatitis. C virus infection in Saudi Arabia: a review. Ann Saudi Med 1997;17:77—82. 11. Zein NN. Clinical significance of hepatitis C virus genotypes. Clin Microbiol Rev 2000;13:223—35. 12. Nguyen MH, Keeffe EB. Epidemiology and treatment outcomes of patients with chronic hepatitis C and genotypes 4 to 9. Rev Gastroenterol Disord 2004;4(Suppl. 1):S14—21. 13. Koshy A, Madda JP, Marcellin P, Martinot M. Treatment of hepatitis C virus genotype 4-related cirrhosis: ribavirin and interferon combination compared with interferon alone. J Clin Gastroenterol 2002;35:82—5. 14. Shiha G, Salem S. Interferon alone or in combination with ribavirin for the treatment of chronic hepatitis C genotype IV. J Hepatol 2002;36:129. 15. Shobokshi OA, Serebour FE, Shakni L. Chronic hepatitis C treatment: a review. Ann Saudi Med 2000;20:402—8. 16. Choo QL, Kuo G, Weiner AJ, Overky LR, Bradley DW, Houghton M. Isolation of a cDNA clone derived from a blood-borne non-A, nonB viral hepatitis genome. Science 1989;244:359—62. 17. Houghton M. Hepatitis C virus. In: Fields BN, Knipe DM, Howley PM, Chanock RH, editors. Fields virology. 3rd ed. Philadelphia: Lippincott—Raven; 1996. p. 1035—58. 18. Tanaka T, Kato N, Cho M, Shimotohno K. A novel sequence found at the 30 terminus of hepatitis C virus genome. Biochem Biophys Res Commun 1995;215:744—9. 19. Choo QL, Richman KH, Han JH, Berger K, Lee C, Dong C, et al. Genetic organization and diversity of the hepatitis C virus. Proc Natl Acad Sci USA 1991;88:2451—5. 20. Weiner AJ, Brauer MJ, Rosenblatt J, Richman KH, Tung J, Crawford K, et al. Variable and hypervariable domains are found in the regions of HCV corresponding to the flavivirus envelope and NS1 proteins and the pestivirus envelope glycoproteins. Virology 1991;180:842—8. 21. Hijikata M, Kato N, Ootsuyama Y, Nakagawa M, Ohkoshi S, Shimotohno K. Hypervariable regions in the putative glycoprotein of hepatitis C virus. Biochem Biophys Res Commun 1991;175:220—8. 22. Simmonds P. Variability of hepatitis C virus. Hepatology 1995;21: 570—83. 23. Tokita H, Okamoto H, Tsuda F, Song P, Nakata S, Chosa T, et al. Hepatitis C virus variants from Vietnam are classifiable into the seventh, eighth and ninth major genetic groups. Proc Natl Acad Sci USA 1994;91:11022—6. 24. Tokita H, Okamoto H, Luengrojanakul P, Vareesangthip K, Chainuvati T, Iizuka H, et al. Hepatitis C virus variants from Thailand

The significance of HCV genotyping as an epidemiological marker has been clearly substantiated, particularly in tracing the sources of infection and elucidating the possible modes of transmission.84,85 However, the issue of pathogenicity of the different genotypes/subtypes is still controversial.9—11,16 Several environmental, genetic, and immunological factors may contribute to the profound differences in disease progression observed in HCV infected patients. Therefore, longterm prospective studies in various population groups are still needed to generate reliable data on the clinical significance of HCV genotypes.

Antiviral therapy In addition to the importance of HCV genotyping as epidemiological markers, most investigators agree on the significance of HCV genotypes as independent predictors of response to antiviral therapy. Major clinical trials of antiviral therapy for chronic HCV have been performed in Western countries84,85 and in Japan.86 Hence, existing published data largely deal with patients with HCV genotypes 1, 2, and 3, and there are now clear-cut guidelines for the type of treatment and duration of antiviral therapy in such patients.87 However there have been relatively few studies that have targeted patients infected with HCV genotype 4, and combination therapy clinical trials (interferon and ribavirin) for these patients have not been promising.88—90 Encouraging results are now being reported on the efficacy of peginterferon in combination with ribavirin given for 48 weeks for the treatment of chronic hepatitis caused by HCV genotype 491—97 with a sustained virologic response ranging from 63 to 82%.91—94 It is evident that more randomized controlled trials of the combined peginterferon plus ribavirin are needed to assess the optimal dosage and duration of therapy and for the eventual establishment of appropriate treatment protocols for these patients.

Challenges It is now clear that HCV genotype 4 is the predominant genotype in the Middle East where one-fifth of the estimated 170 million HCV carriers live. In addition to the possible development of the infection into cirrhosis and HCC, it has been recently observed that there is an increased risk of liverrelated death and demand for liver transplantation in patients infected with HCV genotype 4.98 These facts indicate that the treatment of carriers and prevention of HCV infection are very urgent problems. Efforts to develop more effective antiviral therapies and the establishment of an effective HCV vaccine remain the largest challenges for the near future.

Acknowledgements The authors would like to express their appreciation to Robin Mansur for her assistance in editing the manuscript and to Mrs Maha Abul Naja for her excellent secretarial assistance. Conflict of interest: No conflict of interest to declare.

276

25.

26.

27.

28.

29.

30. 31.

32.

33.

34.

35. 36.

37.

38.

39.

40.

41.

42.

43.

S. Ramia, J. Eid-Fares classifiable into five novel genotypes in the sixth (6b), seventh (7c, 7d) and ninth (9b, 9c) major genetic groups. J Gen Virol 1995;76:2329—35. Mizokami M, Gojobori T, Ohba K, Ikeo K, Ge XM, Ohno T, et al. Hepatitis C virus types 7, 8 and 9 should be classified as type 6 subtypes. J Hepatol 1996;24:622—4. Schreier E, Roggendorf M, Driesel G, Hohne M, Viazov S. Genotypes of hepatitis C virus isolates from different parts of the world. Arch Virol 1996;11(Suppl.):185—93. Ross RS, Viazov SO, Holtzer CD, Beyou A, Monnet A, Mazure C, et al. Genotyping of hepatitis C virus isolates using CLIP sequencing. J Clin Microbiol 2000;38:3581—4. Nakao T, Enomoto N, Takada N, Nakao T, Enomoto N, Takada N, et al. Typing of hepatitis C virus genomes by restriction fragment length polymorphism. J Gen Virol 1991;72(Pt 9):2105— 12. Le Pogam S, Dubois F, Christen R, Raby C, Cavicchini A, Goudeau A. Comparison of DNA enzyme immunoassay and line probe assays (InnoLiPA HCV I and II) for hepatitis C virus genotyping. J Clin Microbiol 1998;36:1461—3. Pawlotsky JM. Use and interpretation of virological tests for hepatitis C. Hepatology 2002;36:S65—73. Pawlotsky JM, Prescott L, Simmonds P, Pellet C, Laurent-Puig P, Labonne C, et al. Serological determination of hepatitis C virus genotype: comparison with a standardized genotyping assay. J Clin Microbiol 1997;35:1734—9. Cerino A, Cividini A, Asti M, Lanza A, Silini E, Mondelli MU. Comparative evaluation of two serologic typing methods of hepatitis C virus. J Clin Microbiol 1996;34:714—6. Bhattacherjee V, Prescott LE, Pike I, Rodgers B, Bell H, El-Zayadi AR, et al. Use of NS-4 peptides to identify type-specific antibody to genotypes 1, 2, 3, 4, 5 and 6. J Gen Virol 1995;76:1737—48. McOmish F, Yap PL, Dow BC, Follett EA, Seed C, Keller AJ, et al. Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey. J Clin Microbiol 1994;32:884—92. Silini E, Mondelli MU. Significance of hepatitis C virus genotypes. Viral Hepat Rev 1995;1:111—20. Mahaney K, Tedeschi V, Maertens G, Di Bisceglie AM, Vergalla J, Hoofnagle JH, et al. Genotypic analysis of hepatitis C virus in American patients. Hepatology 1994;20:1405—11. McOmish F, Chan SW, Dow BC, Gillon J, Frame WD, Crawford RJ, et al. Detection of three types of hepatitis C virus in blood donors: investigation of type-specific differences in serologic reactivity and rate of alanine aminotransferase abnormalities. Transfusion 1993;33:7—13. Nousbaum J-B, Pol S, Nalpas B, Landais P, Berthelot P, Brechot C, Group Collaborative Study. Hepatitis C virus type 1b (II) infection in France and Italy. Ann Intern Med 1995;122:161—8. Viazov S, Kuzin S, Paladi N, Tchernovetsky M, Isaeva E, Mazhul L, et al. Hepatitis C virus genotypes in different regions of the former Soviet Union (Russia, Belarus, Moldova, and Uzbekistan). J Med Virol 1997;53:36—40. Osella AR, Sonzogni L, Cavallini A, Foti L, Guerra V, Di Leo A, et al. Molecular epidemiology of hepatitis C virus infection in an area of hyperendemicity in Southern Italy: a population-based study. J Clin Microbiol 1999;37:2371—2. Silini E, Bono F, Cividini A, Cerino A, Maccabruni A, Tinelli C, et al. Molecular epidemiology of hepatitis C virus infection among intravenous drug users. J Hepatol 1995;22:691—5. Pol S, Thiers V, Nousbaum JB, Legendre C, Berthelot P, Kreis H, et al. The changing relative prevalence of hepatitis C virus genotypes: evidence in hemodialyzed patients and kidney recipients. Gastroenterology 1995;108:581—3. Pawlotsky JM, Tsakiris L, Roudot-Thoraval F, Pellet C, Stuyver L, Duval J, et al. Relationship between hepatitis C virus genotypes and sources of infection in patients with chronic hepatitis C. J Infect Dis 1995;171:1607—10.

44. Djebbi A, Triki H, Bahri O, Cheikh I, Sadraoui A, Ben Ammar A, et al. Genotypes of hepatitis C virus circulating in Tunisia. Epidemiol Infect 2003;130:501—5. 45. Benani A, El-Turk J, Benjelloun S, Sekkat S, Nadifi S, Hda N, et al. HCV genotypes in Morocco. J Med Virol 1997;52:396—8. 46. Cacoub P, Ohayon V, Sekkat S, Dumont B, Sbai A, Lunel F, et al. Epidemiologic and virologic study of hepatitis C virus infection in Morocco. Gastroenterol Clin Biol 2000;24:169—73. 47. Ray SC, Arthur RR, Carella A, Bukh J, Thomas DL. Genetic epidemiology of hepatitis C virus throughout Egypt. J Infect Dis 2000;182:698—707. 48. Xu LZ, Larzul D, Delaporte E, Brechot C, Kremsdorf D. Hepatitis C virus genotype 4 is highly prevalent in Central Africa (Gabon). J Gen Virol 1994;75(Pt 9):2393—8. 49. Oni AD, Harrison TJ. Genotypes of hepatitis C virus in Nigeria. J Med Virol 1996;49:178—86. 50. Njouom R, Pasquier C, Ayouba A, Gessain A, Froment A, Mfoupouendoun J, et al. High rate of hepatitis C virus infection and predominance of genotype 4 among elderly inhabitants of a remote village of the rain forest of South Cameroon. J Med Virol 2003;71:219—25. 51. Smuts HE, Kannemeyer J. Genotyping of hepatitis C virus in South Africa. J Clin Microbiol 1995;33:1679—81. 52. Simmonds P, Mellor J, Sakuldamrongpanich T, Nuchaprayoon C, Tanprasert S, Holmes EC, et al. Evolutionary analysis of variants of hepatitis C virus found in South-East Asia: comparison with classifications based upon sequence similarity. J Gen Virol 1996;77(Pt 12):3013—24. 53. Mellor J, Walsh EA, Prescott LE, Jarvis LM, Davidson F, Yap PL, et al. Survey of type 6 group variants of hepatitis V virus in Southeast Asia by using a core-based genotyping assay. J Clin Microbiol 1996;34:417—23. 54. Sugiyama K, Kato N, Nakazawa T, Yonemura Y, Phornphutkul K, Kunakorn M, et al. Novel genotypes of hepatitis C virus in Thailand. J Gen Virol 1995;76(Pt 9):2323—7. 55. Tokita H, Okamoto H, Tsuda F, Song P, Nakata S, Chosa T, et al. Hepatitis C virus variants from Vietnam are classifiable into the seventh, eighth, and ninth major genetic groups. Proc Natl Acad Sci USA 1994;91:11022—6. 56. Tokita H, Okamoto H, Iizuka H, Kishimoto J, Tsuda F, Miyakawa Y, et al. The entire nucleotide sequences of three hepatitis V virus isolates in genetic groups 79 and comparison with those in the other eight genetic groups. J Gen Virol 1998;79(Pt 8):1847—57. 57. Tokita H, Okamoto H, Iizuka H, Kishimoto J, Tsuda F, Lesmana LA, et al. Hepatitis C virus variants from Jakarta, Indonesia classifiable into novel genotypes in the second (2e and 2f), tenth (10a) and eleventh (11a) genetic groups. J Gen Virol 1996;77(Pt 2):293—301. 58. Katayama Y, Barzaga NG, Alipio A, Soetjipto. Doi H, Ishido S, et al. Genotype analysis of hepatitis C virus among blood donors and inmates in Metro Manila, The Philippines. Microbiol Immunol 1996;40:525—9. 59. Chamberlain R, Adams N, Saeed A, Simmonds P, Elliot R. Complete nucleotide sequence of a type 4 hepatitis C virus variant. The predominant genotype in the Middle East. J Gen Virol 1997;78:1341—7. 60. Fakeeh M, Zaki AM. Hepatitis C: prevalence and common genotypes among ethnic groups in Jeddah, Saudi Arabia. Am J Trop Med Hyg 1999;61:889—92. 61. Ray SC, Arthur RR, Carella A, Bukh J, Thomas DL. Genetic epidemiology of hepatitis C virus throughout Egypt. J Infect Dis 2000;182:698—707. 62. Shemer-Avni Y, el Astal Z, Kemper O, el Najjar KJ, Yaari A, Hanuka N, et al. Hepatitis C virus infection and genotypes in Southern Israel and the Gaza Strip. J Med Virol 1998;56:230—3. 63. Bdour S. Hepatitis C virus infection in Jordanian hemodialysis units: serological diagnosis and genotyping. J Med Microbiol 2002;51:200—4.

Distribution of hepatitis C virus genotypes in the Middle East 64. Pasca A, Al-Mufti S, Chugh T, Said-Adi G. Genotypes of hepatitis C virus in Kuwait. Med Princ Pract 2001;10:55—7. 65. Ramia S, Koussa S, Taher A, Haraki S, Klayme S, Sarkis D, et al. Hepatitis C virus genotypes and hepatitis G virus infection in Lebanese thalassemics. Ann Trop Med Parasitol 2002;96:197— 202. 66. Sharara AI, Ramia S, Ramlawi F, Eid Fares J, Klayme S, Naman R. Genotypes of hepatitis C virus (HCV) among positive Lebanese patients: comparison of data with that from other Middle Eastern countries. Epidemiol Infect; accepted for publication. 67. Al-Ahdal M, Rezeig M, Kessie G. Genotyping of hepatitis C virus isolates from Saudi patients by analysis of sequences from PCRamplified core region of the virus genome. Ann Saudi Med 1997;17:601—4. 68. Shobokshi OA, Serebour FE, Skakni LL. Hepatitis C genotypes/ subtypes among chronic hepatitis patients in Saudi Arabia. Saudi Med J 2003;24(Suppl. 2):S87—91. 69. Shobokshi OA, Serebour FE, Skakni L, Al-Saffy YH, Ahdal MN. Hepatitis C genotypes and subtypes in Saudi Arabia. J Med Virol 1999;58:44—8. 70. Osoba A. Hepatitis C virus genotypes in the Kingdom of Saudi Arabia. Saudi Med J 2002;23:7—12. 71. Abdulkarim AS, Zein NN, Germer JJ, Kolbert CP, Kabbani L, Krajnik KL, et al. Hepatitis C virus genotypes and hepatitis G virus in hemodialysis patients from Syria: identification of two novel hepatitis V virus subtypes. Am J Trop Med Hyg 1998;50:571—6. 72. Sawant P, Upadhyay AP, Levicnik-Stezinar S, Zali MR, Okamoto H. Genotypes of GB virus C and hepatitis C virus in hepatitis patients in India, Iran and Slovenia. Hepatology Res 1998;10:175—83. 73. Samimi-Rad K, Nategh R, Malekzacleh R, Norder H, Magnius L. Molecular epidemiology of hepatitis C virus in Iran as reflected by phylogenetic analysis of the NS5B region. J Med Virol 2004;74:246—52. 74. Weinstein T, Tur-Kaspa R, Chagnac A, Korzets A, Ori Y, Zevin D, et al. Hepatitis C infection in dialysis patients in Israel. Isr Med Assoc J 2001;3:174—7. 75. Bozdayi G, Rota S, Verdi H, Derici U, Sindel S, Bali M, et al. The presence of hepatitis C virus infection in hemodialysis patients and determination of HCV genotype distribution. Mikrobiyol Bul 2002;36:291—300. 76. Bozdayi AM, Aslan N, Bozdayi G, Turkyilmaz AR, Sengezer T, Wend U, et al. Molecular epidemiology of hepatitis B, C and D viruses in Turkish patients. Arch Virol 2004;149:2115—29. 77. Argentini C, Dettori S, Villano U, Guadagnino V, Infantolino D, Dentico P, et al. Molecular characterization of HCV genotype 4 isolates circulating in Italy. J Med Virol 2000;62:84—90. 78. Matera G, Lamberti A, Quirino A, Foca D, Giancotti A, Barreca GS, et al. Changes in the prevalence of hepatitis C virus (HCV) genotype 4 in Calabria, Southern Italy. Diagn Microbiol Infect Dis 2002;42:169—73. 79. Sanchez-Quijano A, Abad MA, Torronteras R, Rey C, Pineda JA, Leal M, et al. Unexpected high prevalence of hepatitis C virus genotype 4 in Southern Spain. J Hepatol 1997;27:25—9. 80. Schroter A, Zollner B, Schafer P, Reimer A, Muller M, Laufs R. Epidemiological dynamics of hepatitis C virus among 747 German individuals: new subtypes on the advance. J Clin Microbiol 2002;40:1866—8. 81. De Ledinghen V, Trimoulet P, Castera L. Unexpected high prevalence of HCV genotype 4 infection in a French Caucasian population. Proceedings of the 53rd Annual Meeting of the American Association for the Study of Liver Diseases; 2002 Nov 1—5; Boston, MA, USA. Orlando, USA: WB Saunders Co.; 2002. 82. Lyra A, Ramrakhiani S, Bacon B, Di Bisceglie A. Infection with hepatitis C virus genotype 4 in the United States. J Clin Gastroenterol 2004;38:68—71.

277 83. Raghuraman S, Abraham P, Sridharan G, Daniel H, Rama-Krishna BS, Shaji R. HCV genotype 4 — an emerging threat as a cause of chronic liver disease in Indian (south) patients. J Clin Virol 2004;31:253—8. 84. McHutchison JG, Gordon SC, Schiff ER, Shiffman ML, Lee WM, Rustgi VK, et al. Interferon-alpha 2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. N Engl J Med 1998;339:1485—92. 85. Poynard T, Marcellin P, Lee SS, Niederau C, Minuk GS, Ideo G, et al. Randomized trial of interferon alpha-2b plus ribavirin for 48 weeks or for 24 weeks versus interferon alpha 2b plus placebo for 48 weeks for treatment of chronic infection with hepatitis C. Lancet 1998;352:1426—32. 86. Okanoue T, Itoh Y, Minami M, Sakamoto S, Yasui K, Sakamoto M, et al. Interferon therapy lowers the rate of progression to hepatocellular carcinoma in chronic hepatitis C but not significantly in advanced stage: a retrospective study in 1148 patients. J Hepatol 1999;30:653—9. 87. Booth JCL, O’Grady J, Neukerger J, on behalf of the Royal College of Physicians of London and the British Society of Gastroenterology. Clinical guidelines on the management of hepatitis C. Gut 2001;49(Suppl. 1):i1—21. 88. Al-Faleh FZ, Aljumah A, Rezeig M, Al-Kanawi. Al-Otaibi M, Alahdal M, et al. Treatment of chronic hepatitis C genotype IV with interferon—ribavirin combination in Saudi Arabia: a multicentre study. J Viral Hepat 2000;7:287—91. 89. Shiha G, Salem S. Interferon alone or in combination with ribavirin for the treatment of chronic hepatitis C genotype IV. J Hepatol 2002;36:129. 90. Koshy A, Madda JP, Marcellin P, Martinot M. Treatment of hepatitis C virus genotype 4-related cirrhosis: ribavirin and interferon combination compared with interferon alone. J Clin Gastroenterol 2002;35:82—5. 91. Fried MW, Shiffman ML, Reddy KR, Smith C, Marinos G, Goncales Jr FL et al. Peginterferon alfa-2a plus ribavirin for chronic hepatitis C virus infection. N Engl J Med 2002;347:975—82. 92. Hadziyannis SJ, Sette Jr H, Morgan TR, Balan V, Diago M, Marcellin P, et al. Peginterferon a-2a and ribavirin combination therapy in chronic hepatitis C. A randomized study of treatment duration and ribavirin dose. Ann Intern Med 2004;140:346—55. 93. Diago M, Hassanein T, Rodes J, Ackrill AM, Sedarati F. Optimized virologic response in hepatitis C virus genotype 4 with peginterferon-alpha2a and ribavirin [Letter]. Ann Intern Med 2004;140:72—3. 94. Hasan F, Asker H, Al Khaldi J, Siddique I, Al-Ajmi M, Owaid S, et al. Peginterferon alfa-2b plus ribavirin for the treatment of chronic hepatitis C genotype 4. Am J Gastroenterol 2004;99:1733—7. 95. Shobokshi OA, Serebour FE, Skakni L, Al-Jaser N, Tantawe AO, Sabah A, et al. Pegylated interferon alfa-2a (40KDA) as a monotherapy or in combination with ribavirin significantly improves end of treatment response rate in hepatitis C virus genotype 4 chronic active hepatitis patients. Saudi Med J 2003; 24:S92—192. 96. Shobokshi OA, Serebour FE, Skakni L, Al-Jaser N, Tantawe AO, Sabah A, et al. Early virological response at week 12 has positive predictive value for end of treatment response for hepatitis C virus genotype 4 chronic active hepatitis cases treated with combination therapy of pegylated interferon plus ribavirin. Saudi Med J 2003;24:S92—3. 97. Khuroo MS, Khuroo MS, Dahab ST. Meta-analysis: a randomized trial of peginterferon plus ribavirin for the initial treatment of chronic hepatitis C genotype 4. Aliment Pharmacol Ther 2004;20:931—8. 98. Zylberberg H, Chaix ML, Brechot C. Infection with hepatitis C virus genotype 4 is associated with a poor response to interferonalpha [Letter]. Ann Intern Med 2000;132:845—6.