Recent discoveries in the etiology of acute respiratory infections: The adenoviruses

Medical Progress R E C E N T D I S C O V E R I E S I N T H E E T I O L O G Y OF A C U T E RESPIRATORY INFECTIONS: THE ADENOVIRUSES ROBERT WARD, M.D. NE~vVYORK, N. Y. OR m a n y y e a r s the t e r m "virus" been bandied about and loosely applied to miscellaneous res p i r a t o r y a n d "grippelike" infections which did not behave like bacterial infections, but whose etiology was r e a l l y in the dark. L a y f r i e n d s ' questions: " W h a t is ' V i r u s ' ? " or " W h a t is ' V i r u s X'~." were not alw a y s easy to answer. The only res p i r a t o r y viruses k n o w n until recently, influenza A and B, psittacosis, and Q fever if one included rickettsiae, accounted for but a small fraction of nonbacterial r e s p i r a t o r y infections. The r e m a i n i n g illnesses, presumably caused b y viruses, were known by various names, such as rhinopharyngitis, the common cold, pharyngitis, laryngitis, traeheitis, bronchitis, grippe, febrile catarrh, virus pneumonia, and so forth. Such terms merely describe the site of the most p r o m i n e n t clinical manifestations. I t is generally appreciated, however, that different agents m a y give rise to clinically indistinguishable illnesses. Infeetion with the same virus, conversely, m a y yield different clinical pictures in different hosts. I t is obvious t h a t an etiolog-

ieal classification of acute respirat o r y infections would be most welcome.

F has

From the Department of Pediatrics, New York U n i v e r s i t y College of Medieine, and the Children's Medical Service, Bellevue Hospital.

480

N o w the c u r t a i n has been lifted, r e v e a l i n g at least a segment of this unexplored territory. I n the last two to three years, a f a m i l y of rel a t e d viruses which possess some v e r y i n t e r e s t i n g p r o p e r t i e s has been discovered. This f a m i l y has been k n o w n v a r i o u s l y as the APC, AD, ARD, and R I v i r u s e s - - a l l v e r y confusing, as n o m e n c l a t u r e is likely to be at the o'pening of a new field. Table I is designed to clarify, in part, this confusion. A committee is of investig a t o r s in this field has recently a g r e e d on the t e r m " a d e n o v i r u s " to replace those listed above. This will be used in the present review except w h e n the original t e r m s will be used f o r historical purposes. The field was opened in 1953 by the b a c k gate, so to speak, b y Rowe and his associates. 1 These i n v e s t i g a t o r s t o o k bits of adenoids surgically rem o v e d f r o m n o r m a l children and cult i v a t e d t h e m in tissue culture. Sheets of epithelial cells grew out f r o m the original f r a g m e n t s . A f t e r eight to twenty-eight days these epithelial cells

481

MEDICAL PROGRESS

began to round up and form clumps, and this progressed to complete degeneration. The fluids from these cultures were passed to fresh cultures of adenoids, to h u m a n embryonic tissue, and to a strain of h u m a n cancer cells k n o w n as tIeLa. Similar degeneration of the cells was observed and the agent was carried thus t h r o u g h m a n y serial passages. It always TABLE I.

I~EW I~ESPItCATORY VIRUSES, TERMINOLOGY AND RELATION TO DISEASE

DESIGNATION ACCORDINGTO INVESTIGATOR

HUEBNEI%

I

panzer, h u m u n i z a t i o n of rabbits with the tissue-culture fluids containing the agent resulted in serum antibodies capable of neutralizing the agent in tissue culture. Immunization with control culture fluid did not. In other words, the agent showed m a n y of the properties of viruses or rickettsiae. The discoverers first called it the " a d e n o i d de-

IIILI,E IYIAN

I GINSBERG

COIV~MITTEE ON NOIV~EN CLATUREI8

-

CLINICAL PICTURE SOURCE OF VIRUS Febrile pharynA d e n o i d s , tonsils, girls in chilN P H secretions dren

~APC T y 1 L a t e n t T y 1

AD 1

Adenovirus

APC

Ty 2 Latent Ty 2

AD 2

Adenovirus 2

Febrile pharyngitis in ehildren ~

Adenoids, tonsils, N P K secretions

APC

T y 3 bRI gp. C

AD 3

Adenovirus 3

P C F , U.R.I., N e v a ' s exanthem

A n a l swabs, conjunctival and N P t t secretions

APC

T y 4 R I gp. A RI-67

A D 4, ARD

Adenovirus 4

dARD, e F A P , ' ' bronchitis ' '

Throat washings, adenoids

APC

Ty 5 Latent Ty 5

AD 5

Adenovirus 5

Febrile pharyngitis in ehildren

A d e n o i d s , tonsils, R-PH secretions

APC

Ty 6 Latent Ty 6

AD 6

Adenovirus 6

PCF

Adenoids, tonsils, N P t I secretions

APC

T y 7 R I gp. B

AD 7

Adenovirus 7

ARD, PAP

Throat washings

APC

Ty 8

AD 8

Adenovirus 8

fEKC

Conjunetival and corneal s c r a p i n g s

1

aAPC : adenoidal-pharyngeal-conjunct~val. bRI: r e s p i r a t o r y illness. e P C F : p h a r y n g o c o n j u n e t i v a l fever. aARD: acute r e s p i r a t o r y disease. " P A P : p r i m a r y atypical pneumonia. fEKC : epidemic keratoconjunctivitis.

p r o d u c e d characteristic cytopathie changes in tissue-culture cells. It did not grow in o r d i n a r y bacteriological media. I t was destroyed by heating at 62 ~ C. for t h i r t y minutes. It was filtrable; it survived freezing and thawing. I t p r o d u c e d no recognizable disease in eggs, suckling and adult mice, suckling hamsters, guinea pigs, rabbits, monkeys, and a chim-

generation a g e n t " or " A D a g e n t . " Although this original approach excited more t h a n a little interest, it should be stressed that at this point there was no e v i d e n c e t h a t the A D a g e n t or v i r u s was related to h u m a n disease. It appeared to be a latent

virus, " u n m a s k e d " by being separ a t e d from man and cultivated in tissue cultures.

482

THE JOURNAL OF PEDIATRICS

P r o o f of a causal relationship to disease in man was not long in coming. Hilleman and Werner, 2 working i n d e p e n d e n t l y of Rowe and his group, r e p o r t e d in 1954 the isolation of several strains of cytopathogenic agents from soldiers with acute respiratory infections at Ft. Leonard Wood in Missouri during the winter of 1952-]953. Most of the patients had an illness known as "AI~D," acute respiratory disease. This was an acute febrile respiratory infection of short duration with both constitutional and local respiratory symptoms. It was characterized mainly by cough and hoarseness. In addition, irritated throat, nasal obstruction, and chest pain were frequent complaints. The incubation period was five to six days. Some of the patients from whom agents were isolated had pulmonary infiltration and were considered to have primary atypical pneumonia ( P A P ) . No cold agglutinins or streptococcus MG agglutinins developed in the l a t t e r patients. Most of them had a rise in neutralizing antibodies against one of the strains isolated, the RI-67 strain. Later it was shown that the RI-67 strain was indistinguishable from AD type 4 isolated by Rowe and co-workers2 I - h e b n e r and his associates 4 rep o r t e d in 1954 t h a t their m a n y AD strains Were found to fall into six distinct serological types. This was done b y p r o d u c i n g immune serum in rabbits injected with various strains. Neutralizing antibodies were demonstrated against the homologous and related strains, but none against heterologous or u n r e l a t e d strains. In contrast to the type specificity of the neutralization test, it was found that

complement-fixing (CF) antigens and antibodies were shared in common by most members of the family. In other words, the CF test revealed general crossing between types, or group specificity. The practical irap o r t a n e e of the CF test in a screening s u r v e y is obvious. Once having f o u n d CF antibody, one could then employ the neutralization test to det e r m i n e the specific type involved. P a r r o t t and others ~ investigated an o u t b r e a k in F e b r u a r y , 1954, afl e t t i n g f o u r patients and f o u r hospital staff members with a febrile illness h a v i n g the following characteristies: fever up to 104 ~ F., pharyngitis, rhinitis, cervical lymphadenitis, and conjunctivitis. Three had t r a n s i t o r y liver enlargement, accompanied b y tenderness in two. AD virus, t y p e 3, was detected in six patients. In five it was isolated from swabs of the nasopharynx, and in one f r o m the conjunetival swab. Most of the eight patients showed both CF and neutralizing antibody rises. The occurrence of p h a r y n g i t i s and conjunctivitis in patients from w h o m these viruses were recovered, and clean-cut evidence of antibody response in convalescence, to the same agents, led H u e b n e r and his associates to change their designation f r o m AD to APC viruses (adenoidal-pharyngeal-eonjunctival). D u r i n g the summer of 1954, Bell and his associates 6 studied over three h u n d r e d cases occurring in three outbreaks of an acute r e s p i r a t o r y illness which they called pharyngoconjunctival fever. This illness was similar to the small hospital o u t b r e a k just described, and adenovirus type 3 was isolated in H e L a cell culture tubes f r o m the eye, throat, and anal swabs.

MEDICAL PROGRESS

Classical antibody rises confirmed the etiology. The clinical picture was characterized mainly by fever, sore throat, and conjunctivitis. In addition, there were headache and lassitude in the majority of cases. Fever, often the chief complaint, lasted for an average of five to six days (range, one to ten), and then came down by lysis. Sore throat was generally mild, being described more as " s c r a t c h y " rather than as painful swallowing. Physical findings were not striking except for injection of the posterior pharyngeal wall which was studded with glairy lymph follicles. Nontender, submaxillary lymph nodes were commonly felt. The conjunctivitis lasted for a few days to three weeks. Mild, follicular injection of both bulbar and palpebral conjunctivae was observed, often in one eye only. E xuda t e was rarely purulent. Scanty serous exudate with slight matting of eyelids and increased lacrimation were not uncommon. Photophobia and retroorbital pain were practically nonexistent. No corneal or uveal involvement was seen. Otitis media was infrequent, usually nonpurulent, and did not seem to respond well to antibiotics. Muscle, bone, and joint aches, and weakness were seen occasionally, particularly in adults. Laboratory findings except for possible leukopenia were negative. There were no deaths. While these studies were in progress, Ginsberg and his associates r in Cleveland took the cue from ttilleman that ARD and P A P in soldiers at Ft. Leonard Wood was caused by 1%I-67 virus (adenovirus type 4). They wondered if perhaps the ARD seen during World W a r II at Ft.

483

Bragg and subsequently at other military installations might not have had a similar etiology. Human transmission experiments reported ~,'9 a decade earlier had indicated a probable viral etiology for PAP and ARD. Fortunately preinfection and convaleseent sera had been saved from the donor and recipients of ARD material. It t urned out that these individuals had developed neutralizing antibody to adenovirus type 4 but none to types ], 2, or 3. Also in retrospect, it was found that the illness, ARD, had occurred in the majority of recipients who had no antibody in the preinoculation sera. Emergence and rise of type 4 'antibodies occurred in all recipients whose preinoculation sera were devoid of antibodies. Moreover, the majority of recipients whose preinoculation sera contained type 4 antibodies had been resistant to experimental, infection and did not show f u r t h e r increase in antibodies. It appeared likely from the evidence provided by these retrospective studies that adenovirus type 4 is related etiologically to ARD studied during World W a r II by the Commission for Acute Respiratory Diseases. Recently another member of the adenovirus group, known as type 7, has been isolated by Berge and his associates 1~ from the throat washings in 44 per cent of respiratory illnesses studied at F o r t 0rd, California. Types 4 and 7 appear to be the two commonest adenoviruses associated with respiratory illness in military populations. Population groups have been investigated 15 serologically for antibodies to the adenoviruses. Types 1 and 2 antibodies were found corn-

~8~

THE JOURNAL OF PEDIATRICS

monly in children. T y p e 3 antibodies were f o u n d in relation to o u t b r e a k s of n o n b a e t e r i a l p h a r y n g i t i s . Antibodies to other t y p e s were i n f r e q u e n t in children. I n Cleveland, t y p e 4 antibodies h a v e not been f o u n d in subjects u n d e r the age of 17 years. I f this is f o u n d generally, it m a y partially explain w h y A R D infection with t y p e 4 occurs in m i l i t a r y recruits2 6 Studies j u s t b e g u n in our laborat o r y ~7 indicate a relationship between the adenoviruses and certain acute r e s p i r a t o r y infections in i n f a n t s admitted to Bellevue Hospital. Significant CF a n t i b o d y rises were f o u n d in eleven of eighteen i n f a n t s with bronchiolitis, two of eight infants with l a r y n g o t r a c h e o b r o n c h i t i s , a n d none of five diagnosed as h a v i n g bronchopneumonia. A d e n o v i r u s t y p e 8 has been described b y J a w e t z and his group21 These w o r k e r s p r e s e n t e d evidence for association of t y p e 8 with epidemic keratoconjunetivitis (EKC). The a g e n t was isolated f r o m the eye of a seaman w i t h t y p i c a l EKC. Neutralizing a n t i b o d y rises t o this virus were r e p o r t e d in tests of p a i r e d sera f r o m other patients. Rowe ~z r e p o r t e d recently t h a t the a d e n o v i r u s f a m i l y consists of at least seventeen serologically distinct viruses h a v i n g similar properties, including c o m m o n complement-fixing antigens. Three of these strains were isolated f r o m p r i m a t e s and h a v e not been associated w i t h h u m a n illness. H u e b n e r and collaborators aa have described the use of a killed t y p e 3 vaccine in adult volunteers. Following i n j e c t i o n of vaccine, antibodies were m e a s u r e d and the subjects were challenged w i t h homologous virus.

Significant protection was achieved a n d this was correlated w i t h the presence of detectable antibody. These findings suggest t h a t vaccines could be m a d e with other m e m b e r s of this group, such as t y p e s 4 and 7, the p r e d o m i n a t i n g strains in A R D of mili t a r y recruits. Hilleman 1~ and others have recently reported the development of such a bivalent formalin-killed vaccine containing t y p e s 4 and 7. The vaccine was r e p o r t e d (1) to have s t i m u l a t e d high levels of n e u t r a l i z i n g a n t i b o d y and (2) to be at least 90 p e r cent effective in p r e v e n t i n g acute r e s p i r a t o r y illness of a d e n o v i r u s etiology in recruits. T o d a y the i n t e r v a l between the isolation of new viruses and the prepa r a t i o n of effective vaccines a p p e a r s to be shortening. The d i s c o v e r y of the adenoviruses represents a salient advance, but m a n y p r o b l e m s in the field of r e s p i r a t o r y infections r e m a i n to be conquered. Not the least of t h e m is the common cold. So far, no relationship b e t w e e n the common cold a n d a n y m e m b e r s of the a d e n o v i r u s g r o u p or a n y other k n o w n virus has b e e n established. REFERENCE S 1. Rowe, W. P., ttuebner, R. 3-, Gibnore, L. I~., Parrott, R. It., and Ward, T. G.: Iso]atlon of a Cytopathogenie Agent From Human Adenoids Undergoing Spontaneous Degeneration in Tissue Culture, Proc. Soc. Exper. Biol. & M e d . 84: 570~ 1953. 2. Itilleman, IV[. R., and Werner, J. H.: Recovery of a New Agent From Patients With Acute Respiratory Illness, Proc. Soc. Exper. Biol. & ~r 85: 183, 1954. 3. Rowe, W. P., Huebner, R. J., Eart]ey, J. W., Ward, T. G., and Parrot, R. H.: Studies on the Adenoidal-PharyngealConjunctiva] (APC) Group of Viruses, Am. J. Hyg. 61: 197, 1955. 4. Huebner, R. 3., Rowe, W. P., Ward, T. G., Parrott, R. H., and Bell, J. A.: Addenoidal-Fharyngeal-Conjunctival Agents,

MEDICAL

A Newly Recognized Group of Common Respiratory System Viruses, New England J. Med. 251: 1077, 1954. 5. Parrott, R. K., Rowe, W. P., Huebner, R. J., Bernton, It. W., and MeCullogh, N.B.: Outbreak of Febrile Pharyngitis and Conjunctivitis Associated With Type 3 APC Virus Infection, New England J. 3led. 251: 1087, 195~. 6. B e l l , . J . A . , Rowe, W. P., Engler, J. I., Parrott , R. H., and Huebner, R. J.: Pharyngoeon~unctival Fever: Epidemiological Studies of a Recently Recognized Disease Entity, J. A. /V[. A. 157: 1083, 1955. 7; Ginsberg, i-~. S., ~adger~ G. F., Dingle, g. H., Jordan, W. S., Jr., and Katz, S.: Etiologic Relationship of the RI-67 Agent to "-Acute Respiratory Disease ( A R D ) , " J. Cliu. Invest. 3~: 820, 1955.

8. Commission on Acute Respiratory Diseases: The Transmission of Primary Atypical Pneumonia to Human Volunreefs, Bull. Johns Hopkins tIosp. 79: 97, 1946. 9. Commission on Acute Respiratory Diseases: Experimental Transmission of lV[inor Respiratory Illness to Human Volunteers by Filter-passing Agents. II. Immunity on Reinoculation With Agents From the Two Types of iViinor Respiratory Illness and From Primary Atypical Pnemnonia, J. Clin. Invest. 26: 974, 1947. 10. Berge, T. 0 , England, B., 3s C., Shuey, H. E., and Lennette, E. tI.: Etiology of Acute Respiratory Disease Among Service Personnel at Fort Ord, California, Am. J. Hyg. 62: 283, 1955.

PROGRESS

485

11. Jawetz, E., Ximura, S., Nicholas, A. N., Thygeson, P., and Hanna, L.: New Type of APC Virus From Epidemic Xeratoconjunetivitis, Science 122: 1190, 1955. 12. Rowe, W. P.: Conference on Viruses in Search of Disease, New York Academy of Sciences, Section on Biology, i~ay 24-25, 1956. 13. Huebner, R. J., Bell, J. A., Rowe, W. P., Ward, T. G, Suskind, R. G., Hartley, J. W., and Paffenbarger, R. S.: Studies of Adenoidal-Pharyngeal-Conjunetival Vaccines in Volmlteers, J. A. ~[. A. 159: 986, 1955. 14. Hilleman, M. R., Stallones, R. A., Gauld, R. L., Warfleld, IV[. S., and Anderson, S. A.: Prevention of Acute Respiratory Illness in Recruits by Ade*aovirus (R IAPC-ARD) Vaccine, Proe. Soe. Exper. Biol. & iKed. 92: 377, 1956. 15. Jordan, ~V. S., Jr., Badger, G. F., Dingle, J. H., Ginsberg, tI. S., and Katz, S.: Serologic Epidemielogy of Respiratory Agents Isolated in H e L a Cell Cultures, J. Lab. & Clin. Med. 44: 816, 1954.

16. Dingle, J. K., and Feller, A, E.: Noninfluenzal Viral Infections of the Respiratory Tract, New England J. Med. 254: 465, 1956. 17. Winter, g. L., and Chang, S.: Unpublished observations. 18. Enders, J. F., Bell, J. A., Dingle, J. tI., Francis, T., Jr., Hilleman, M. R , Huebher, R. J., and Payne, A. M.-M.: "Adenoviruses": Group Name Proposed for New Respiratory Tract Viruses, Science 124: 119, 1956.