Archives of Virology 50, 335--337 (1976) © by Springer-Verlag 1976
Does Adenovirus Subtype 7a Exist? Brief Report By R. WmAND National Reference Center for Adenoviruses of the Federal Republic of Germany, Homburg (Saar), Federal Republic of Germany Accepted November 28, 1975
Summary Except for its original description (8), the "subtype adenovirus 7 a " has never been found to be antigenically different from type 7. Strain S-1058 (formerly 7a) should serve as the prototype strain of adenovirus 7. , Row~ et al. (8) reported on some antigenic differences between adenovirus 7 strains b y cross-neutralization. Accordingly, they separated a group of closely related strains as "adenovirus type 7 a " (prototype S-1058) from another group closely related to the prototype Gomen strain (type 7). I n the same year, however, B I ~ ¢ et al. (1) found only shght differences between the two prototype strains b y cross-neutralization with rabbit antisera and no difference at all in the antibody response of h u m a n vohmteers immunized with a type 7 vaccine. While our group (12) was unable to prove an antigenic difference, I~A~AJXO (6), comparing various strains of types 3 and 7, did not consider slight titer differences seen in crossneutralization as significant. For the preparation of antisera, the strain S-1058 (7a) has widely been used (5, 4, 9), presumably on the assumption t h a t the 7a (or 7 prime) antiserum might neutralize other type 7 strains more efficiently. On the basis of the studies quoted above (1, 12, 6) the subtype specificity of adenovirus 7 a was already open to doubt. Nevertheless, during the last years at least three working groups (2, 3, 10) reported on isolations and testing of type " 7 a " strains from patients, merely because a type 7a antiserum had been used for typing these isolates (personal communication from 2 of the 3 groups). This prompted us to test rabbit antisera prepared with both prototype strains (Gomen and S-1058) and also with S-1058 after being cloned b y two terminal dilutions in H E K cells (tt) against each other as well as against a number of unselected type 7 wild strains, isolated from various parts of Germany. Reference rabbit antisera distributed b y the National Institute of Health, Bethesda, were also used. The prototype strains were in the 12th or 13th I-IeLa passage, the wild strains were used in their first to third t t e L a passage. Neutralization tests were performed Arch. ViroL 50/4
22
336
R. WIOAND :
according to t h e m e t h o d of l~owE e$ al. (8). As m a y be seen from T a b l e 1, v i r t u a l l y no difference in n e u t r a l i z a t i o n titers of t h e a n t i s e r a a g a i n s t t h e various t y p e 7 strains were observed. P a r t i c u l a r l y , t h e t i t e r r a t i o of t y p e 7 a vs. t y p e 7 a n t i s e r u m was i d e n t i c a l for all strains. I n o t h e r words, no antigenic h e t e r o g e n e i t y was d e m o n s t r a b l e b y cross-neutralization. F u r t h e r m o r e , we f o u n d t h e s t r a i n S-1058 to be suitabte for d e m o n s t r a t i n g t i t e r rises of n e u t r a l i z i n g a n t i b o d i e s in p a t i e n t s infected w i t h a d e n o v i r u s t y p e 7. F r o m 32 p a i r e d sera o n l y 2 failed to show a fourfold or g r e a t e r t i t e r rise w i t h S-1058, a n d these two likewise d i d n o t show a rise w i t h the G o m e n strain. As a consequence, n o t w i t h s t a n d i n g t h e e a r l y results of I~OWE e t a l . (8), I r e c o m m e n d to continue to use t h e s t r a i n S-1058 as t h e p r o t o t y p e s t r a i n of t y p e 7 a n d to abolish a l t o g e t h e r t h e t e r m " t ~ ) e or s u b t y p e 7 a " . ~rhile i n t r a t y p i c a n t i g e n i c v a r i a t i o n s a m o n g a d e n o v i r u s e s m a y exist (6, 7), t h e y do n o t w a r r a n t the d e l i n e a t i o n of s u b t y p e s . A d e n o v i r u s s e r o t y p e s are defined a n d i d e n t i f i e d u n e q u i v o c a l l y b y m e a n s of t h e i r q u a l i t a t i v e a n t i g e n i c distinctiveness. H o w e v e r , a more clear-cut u n d e r s t a n d i n g of i n t r a t y p i c v a r i a t i o n a n d a d i s t i n c t i o n of s u b t y p e s , if existing a t all, would h a v e to w a i t for a g e n e r a l l y a c c e p t e d s t a n d a r d i z e d n e u t r a l i z a t i o n technique. Table 1. Neutralization of adenovirus 7 strains by Gomen and S-1058 antisera R~eciprocal a n t i b o d y titer with antiserum prepared against
Virus
Gomen
S-1058
Titer ratio Col. 5/ Col. 3
Strain
Year and place of isolation
own
NII-I
own
NIH
Gomen S-1058
1954, F o r d Baker 1955, Bethesda
320 320
160 160
1280 1280
40 80
4 4
Ba Wa Ma 34112 Zi
1973, 1973, 1968, 1969, 1973,
160 160 640 320 320
80 80
640 640 2560 1280 1280
80 80
4 4 4 4 4
Homburg Homburg Munich Harmover Wiedenbrfick
Aeknowledgments The s t u d y was aided b y a grant from the Bundesministerium ffir Jugend, Familie und Gesundheit of the F R G . The technical assistance provided b y Miss Doris Keller is gratefully acknowledged.
Referenees 1. BINN, L. N., HILLEMAN, M. 1%., RODRIGU2EZ,J. E., GLABERE, M. 1:~.: Antigenic relationships among adenoviruses wi~h appraisal of reliability of complementfixation test for typing isolates. J. Immunology 80, 501--508 (1958). 2. HARRIS, D. J., WULFF, H., RAY, C. G., POLAND,tl. D., CHIN, T. D. Y., WENNEI¢, H. A. : Viruses and disease: I I I . An outbreak of adenovirus t y p e 7A in a children's home. Amer. J. Epidemiol. 93, 399--402 (1971). 3. HIERHOLZEI~, J. C., PUMAROLA, A., RODRIGUEz-ToI~RES, A,, BELTlCAN, )]~. : 0ccurrence of respiratory illness due to an atypical strain of adenovirus t y p e 11 during a large outbreak in Spanish military recruits. Amer. J. Epidemiol. 99, 434--442 (1974).
Does Adenovirus Subtype 7 a Exist ?
337
4. LUCAS,J. B., JOhnSTON, J. G., Jl~., KAYE, H. S., BUCOA~1V~.A., l~osI~SO~, 1~. Q.: Production of adenovirus antiserums in horses. Public Health Reports 80, 647--652 (1965). 5. !gAFAJKO, 1%. R. : Production and staaadardization of adenovirus types 1 to 18 reference antisera. Amer. J. Hyg. 79, 310--319 (1964). 6. lZAFAJS:O,lZ. R. : Studies on serological relationships between strains of adenovirus types 3 and 7. Proe. Soe. exp. Bioh (N.Y.) 124, 580--585 (1967). 7. RAFAJ~O, 1~. 1~., YOVNG, J. C.: Antigenic variation among adenovirus type 12 strains. J. Bacterioh 90, 292--293 (1965). 8. ROWE, W. P., HAttTLEY, J. W., HUEBNEtt, ]~. J. : Serotype composition of the adenovirus group. Proc. Soc. exp. Biol. (N.Y.) 97, 465--470 (1958). 9. STEVENS, D. A., SCnAEF~E~, M., FOX, J. P., BRANDT, C. D., ROMANO, M. : Standardization and certification of reference antigens and antisera for 30 h u m a n adenovirus serotypes. Amer. J. Epidemioh 86, 617---633 (1967). 10. VASSA~ II, J. H., :gAY, C. G. : Serotyping of adenoviruses using immune electron microscopy. Appl. Microbiol. 28, 623--627 (1974). 11. WIGAI~D, R.: Terminal dilution purification of adenovirus prototypes, and the antigenic relationship between types 4, 16 and 14. Arch. Virol. 49, 323--328 (1975). 12. WIGAND, l~., BAUEI~, H., LA~G, F., ADAM, W. : Neutralization of the adenoviruses types 1 to 28: specificity and antigenic relationships. Arch. ges. Virusforsch. 15, 188--199 (1965). Author's address: Dr. R. WICAND, I n s t i t u t ftir Hygiene u n d Mikrobiologie der UniversitAt des Saarlandes, Universit£ts-Kliniken tIaus 6, D-6650 Homburg (Saar), Federat lgepublic of Germany. t~eceived November 6, 1975
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Does Adenovirus Subtype 7a Exist? Brief Report By R. WmAND National Reference Center for Adenoviruses of the Federal Republic of Germany, Homburg (Saar), Federal Republic of Germany Accepted November 28, 1975
Summary Except for its original description (8), the "subtype adenovirus 7 a " has never been found to be antigenically different from type 7. Strain S-1058 (formerly 7a) should serve as the prototype strain of adenovirus 7. , Row~ et al. (8) reported on some antigenic differences between adenovirus 7 strains b y cross-neutralization. Accordingly, they separated a group of closely related strains as "adenovirus type 7 a " (prototype S-1058) from another group closely related to the prototype Gomen strain (type 7). I n the same year, however, B I ~ ¢ et al. (1) found only shght differences between the two prototype strains b y cross-neutralization with rabbit antisera and no difference at all in the antibody response of h u m a n vohmteers immunized with a type 7 vaccine. While our group (12) was unable to prove an antigenic difference, I~A~AJXO (6), comparing various strains of types 3 and 7, did not consider slight titer differences seen in crossneutralization as significant. For the preparation of antisera, the strain S-1058 (7a) has widely been used (5, 4, 9), presumably on the assumption t h a t the 7a (or 7 prime) antiserum might neutralize other type 7 strains more efficiently. On the basis of the studies quoted above (1, 12, 6) the subtype specificity of adenovirus 7 a was already open to doubt. Nevertheless, during the last years at least three working groups (2, 3, 10) reported on isolations and testing of type " 7 a " strains from patients, merely because a type 7a antiserum had been used for typing these isolates (personal communication from 2 of the 3 groups). This prompted us to test rabbit antisera prepared with both prototype strains (Gomen and S-1058) and also with S-1058 after being cloned b y two terminal dilutions in H E K cells (tt) against each other as well as against a number of unselected type 7 wild strains, isolated from various parts of Germany. Reference rabbit antisera distributed b y the National Institute of Health, Bethesda, were also used. The prototype strains were in the 12th or 13th I-IeLa passage, the wild strains were used in their first to third t t e L a passage. Neutralization tests were performed Arch. ViroL 50/4
22
336
R. WIOAND :
according to t h e m e t h o d of l~owE e$ al. (8). As m a y be seen from T a b l e 1, v i r t u a l l y no difference in n e u t r a l i z a t i o n titers of t h e a n t i s e r a a g a i n s t t h e various t y p e 7 strains were observed. P a r t i c u l a r l y , t h e t i t e r r a t i o of t y p e 7 a vs. t y p e 7 a n t i s e r u m was i d e n t i c a l for all strains. I n o t h e r words, no antigenic h e t e r o g e n e i t y was d e m o n s t r a b l e b y cross-neutralization. F u r t h e r m o r e , we f o u n d t h e s t r a i n S-1058 to be suitabte for d e m o n s t r a t i n g t i t e r rises of n e u t r a l i z i n g a n t i b o d i e s in p a t i e n t s infected w i t h a d e n o v i r u s t y p e 7. F r o m 32 p a i r e d sera o n l y 2 failed to show a fourfold or g r e a t e r t i t e r rise w i t h S-1058, a n d these two likewise d i d n o t show a rise w i t h the G o m e n strain. As a consequence, n o t w i t h s t a n d i n g t h e e a r l y results of I~OWE e t a l . (8), I r e c o m m e n d to continue to use t h e s t r a i n S-1058 as t h e p r o t o t y p e s t r a i n of t y p e 7 a n d to abolish a l t o g e t h e r t h e t e r m " t ~ ) e or s u b t y p e 7 a " . ~rhile i n t r a t y p i c a n t i g e n i c v a r i a t i o n s a m o n g a d e n o v i r u s e s m a y exist (6, 7), t h e y do n o t w a r r a n t the d e l i n e a t i o n of s u b t y p e s . A d e n o v i r u s s e r o t y p e s are defined a n d i d e n t i f i e d u n e q u i v o c a l l y b y m e a n s of t h e i r q u a l i t a t i v e a n t i g e n i c distinctiveness. H o w e v e r , a more clear-cut u n d e r s t a n d i n g of i n t r a t y p i c v a r i a t i o n a n d a d i s t i n c t i o n of s u b t y p e s , if existing a t all, would h a v e to w a i t for a g e n e r a l l y a c c e p t e d s t a n d a r d i z e d n e u t r a l i z a t i o n technique. Table 1. Neutralization of adenovirus 7 strains by Gomen and S-1058 antisera R~eciprocal a n t i b o d y titer with antiserum prepared against
Virus
Gomen
S-1058
Titer ratio Col. 5/ Col. 3
Strain
Year and place of isolation
own
NII-I
own
NIH
Gomen S-1058
1954, F o r d Baker 1955, Bethesda
320 320
160 160
1280 1280
40 80
4 4
Ba Wa Ma 34112 Zi
1973, 1973, 1968, 1969, 1973,
160 160 640 320 320
80 80
640 640 2560 1280 1280
80 80
4 4 4 4 4
Homburg Homburg Munich Harmover Wiedenbrfick
Aeknowledgments The s t u d y was aided b y a grant from the Bundesministerium ffir Jugend, Familie und Gesundheit of the F R G . The technical assistance provided b y Miss Doris Keller is gratefully acknowledged.
Referenees 1. BINN, L. N., HILLEMAN, M. 1%., RODRIGU2EZ,J. E., GLABERE, M. 1:~.: Antigenic relationships among adenoviruses wi~h appraisal of reliability of complementfixation test for typing isolates. J. Immunology 80, 501--508 (1958). 2. HARRIS, D. J., WULFF, H., RAY, C. G., POLAND,tl. D., CHIN, T. D. Y., WENNEI¢, H. A. : Viruses and disease: I I I . An outbreak of adenovirus t y p e 7A in a children's home. Amer. J. Epidemiol. 93, 399--402 (1971). 3. HIERHOLZEI~, J. C., PUMAROLA, A., RODRIGUEz-ToI~RES, A,, BELTlCAN, )]~. : 0ccurrence of respiratory illness due to an atypical strain of adenovirus t y p e 11 during a large outbreak in Spanish military recruits. Amer. J. Epidemiol. 99, 434--442 (1974).
Does Adenovirus Subtype 7 a Exist ?
337
4. LUCAS,J. B., JOhnSTON, J. G., Jl~., KAYE, H. S., BUCOA~1V~.A., l~osI~SO~, 1~. Q.: Production of adenovirus antiserums in horses. Public Health Reports 80, 647--652 (1965). 5. !gAFAJKO, 1%. R. : Production and staaadardization of adenovirus types 1 to 18 reference antisera. Amer. J. Hyg. 79, 310--319 (1964). 6. lZAFAJS:O,lZ. R. : Studies on serological relationships between strains of adenovirus types 3 and 7. Proe. Soe. exp. Bioh (N.Y.) 124, 580--585 (1967). 7. RAFAJ~O, 1~. 1~., YOVNG, J. C.: Antigenic variation among adenovirus type 12 strains. J. Bacterioh 90, 292--293 (1965). 8. ROWE, W. P., HAttTLEY, J. W., HUEBNEtt, ]~. J. : Serotype composition of the adenovirus group. Proc. Soc. exp. Biol. (N.Y.) 97, 465--470 (1958). 9. STEVENS, D. A., SCnAEF~E~, M., FOX, J. P., BRANDT, C. D., ROMANO, M. : Standardization and certification of reference antigens and antisera for 30 h u m a n adenovirus serotypes. Amer. J. Epidemioh 86, 617---633 (1967). 10. VASSA~ II, J. H., :gAY, C. G. : Serotyping of adenoviruses using immune electron microscopy. Appl. Microbiol. 28, 623--627 (1974). 11. WIGAI~D, R.: Terminal dilution purification of adenovirus prototypes, and the antigenic relationship between types 4, 16 and 14. Arch. Virol. 49, 323--328 (1975). 12. WIGAND, l~., BAUEI~, H., LA~G, F., ADAM, W. : Neutralization of the adenoviruses types 1 to 28: specificity and antigenic relationships. Arch. ges. Virusforsch. 15, 188--199 (1965). Author's address: Dr. R. WICAND, I n s t i t u t ftir Hygiene u n d Mikrobiologie der UniversitAt des Saarlandes, Universit£ts-Kliniken tIaus 6, D-6650 Homburg (Saar), Federat lgepublic of Germany. t~eceived November 6, 1975
22*
