Kaprelyan, G.

Karaivanova, L.

Lyutzkanova, V.

Nikolova, N.

Rusev, V.

Saruyan, A

English

Varna Medical University Press: Journals

I I I . Prophylactical problems ON SOME BIOLOGICAL P R O P E R T I E S OF INFLUENZA V I R U S E S T Y P E A ISOLATED DURING T H E PERIOD 1981-1983 G . Kaprelyan, L . Karaivanova, N. Nikolova, V . Rusev, A . Saruyan, V. Lyutzkanova K e y - w o r d s : in f luenza v i r u s type A — an t igen ic s t ruc ture — biology — V a r n a c i t y A basic and unique feature of influenza viruses type A is their unceasing an-tigenic instability (antigenic drift or shift) which has an effect on their biological properties (1—6). It is found out that the activity of the epidemic process is deter-mined by the appearance and distribution of viral varieties with altered enve-lope antigens (7—11). Recently, two antigenic subtypes of influenza virus type A are in an epidemic circulation, namely A ( H l N l ) and A(H3N2). Their simul-taneous circulation suggests the possibility for the origin of recombinants or, at least, for reciprocal influence of some biological properties. The present work is a stage of an overall and systemic investigation of the circulation of influenza viruses in respect to the etiologic prognostication of in-fluenza infections and to an eventual selection of vaccinal strains. Material and methods The following main properties of influenza viruses type A isolated in 1981-1983 were studied: isolation ability on chick embryo model; antigenic structure; sensibility to nonspecific inhibitors; elution activity; hemagglutinin thermosta-bility; infectiousness and toxicity; and cell culture adaptation ability. The me-thods used were previously described (4, 6, 8, 12). Results and discussion Influenza virus isolation from nose-throat washing of patients with clinical diagnosis "influenza" and "acute respiratory disease" showed certain differences. The highest isolation rates were in 1981 — 11,78 per cent, followed by these in 1983 — 3,44 per cent, and in 1982— 1,2 per cent. It could be due to the diffe-rence of epidemic waves intensity and of antigenic structure of predominant in-fluenza virus strains in these years. Influenza viruses with an antigenic formula A(H1N1) were more easily isolated than these with a formula A(H3N2). Our studies demonstrated that influenza viruses type A(H1N1) predominated in the district of Varna in 1981 and 1983. We examined the antigenic structure and som.3 basic biological properties of a certain part of the isolated viruses. It was shown that influenza viruses circu-lating in the district of Varna during this period were antigenically most closely related to the standard strains A(Texas) 1/77(H3N2) and A(Brazil) 1/78(H1N1) (table 1). Newrly isolated strains with an antigenic formula A(H1N1) receded from O n some biological properties of inf luenza. 125 he standard ones — A(Klim)49 and A(USSR)90/77 which were antigenically very closely related with the circulating influenza viruses in the district of Varna dur­ing the period from 1978 ti l l 1980. Similar data were reported by the National influenza centre when other districts in our country were concerned. T a b l e 1 Antigenic s tructure of influenza v irus s tra ins isolated in the V a r n a district in 1981-1983 x S л a г» С О DC — E ~ Е о л fro С/) 2 Z Homologous serum I A V n / 7 4 8 / 8 1 A V n / 6 7 / 8 1 A V n / 1 1 4 7 / 8 1 A V n / 7 5 9 / 8 1 A V n / 6 9 / 8 1 A V n / 3 5 / 8 1 A V n / 4 7 / 8 3 A V n / 5 2 / 8 3 A V n / 1 4 3 / 8 3 A V n / 1 4 9 / 8 3 A V n / 1 5 1 / 8 3 800 800 J 400 1 200 6400 6400 1 400 400 400 3200^ 200 800j 400 -H 3 N 2 1/8 1/4 1/8 0 0 0 0 0 0 0 0 0 0 H 1 N 1 0 0 0 0 1/8 1/32 1/4 1/16 0 0 0 0 0 0 0 H 1 N 1 0 0 0 0 1/16 1/32 1/4 1/32 0 0 0 0 0 0 0 H I N T 1/4 1/2 1/2 0 0 0 0 0 0 0 0 0 0 0 0 H 3 N 2 0 0 0 0 1/4 1/16 1/2 1/4 0 0 0 0 0 0 0 H 3 N 2 0 0 0 0 1/8 1/32 1/4 1/16 0 0 0 0 0 0 0 H 3 N 2 0 0 0 0 1/16 0 1/2 1/8 0 0 0 0 0 0 0 H 3 N 2 0 0 0 0 1/32 1/32 1/2 1/16 0 0 0 0 0 0 0 H 1 N 1 1/32 1/16 1/4 0 0 0 0 0 0 0 0 0 0 0 0 H 1 N 1 0 1/16 1/2 0 0 0 0 0 0 0 0 0 0 0 0 H 1 N 1 1/32 1/8 1/2 0 0 0 0 0 0 0 0 0 0 0 0 T a b l e 2 Results from the hemagglutination activity of inf luenza v i ruses isolated in 1981-1983 l % erythrocyte suspension from Strain Antigenic formula Guinea Pig Rabbit Pigeon Rat Lamb Swine Human Cattle Ram A V n / 3 5 / 8 1 A V n / 6 7 / 8 1 A V n / 4 8 / 8 1 H 3 N 2 H 3 N 2 H 1 N 1 1/256 1/32 1/128 0 0 0 1/64 1/32 1/32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A V n / 6 / 8 2 H 3 N 2 A V n / 1 0 / 8 2 H 3 N 2 A V n / l 16/82 H 3 N 2 1/64 1/128 1/128 1/4096 1/16 1/4096 1/128 1/4096 1/128 1/4096 — 1/4096 — 1/4096 — 1/4096 1/4096 1/4096 1/1024 1/512 1/2048 1/4096 1/4096 1/4096 1/2048 1/128 1/1024 A V n / 4 7 / 8 3 A Vn/143/83 A V n / 1 4 9 / 8 3 H 3 N 2 H 1 N 1 H 1 N 1 1/128 1/1024 1/256 1/4096 1/64 1/4096 1/1024 1/4096 1/64 1/4096 — 1/4096 — 1/4096 — 1/128 1/32 1/256 1/4096 1/4096 1/4096 1/8 1/4096 1/64 1/1024 1/128 1/256 The hemagglutination activity (HA) of the strains increased (table 2), i . e-the hemagglutination spectrum broadened. There was no direct correlation be­tween HA and antigenic formula of influenza virus strains. Influenza virus HA can be suppressed by non-specific inhibitors from the serum of various animal species. Virus sensitivity increase towards nonspecific inhibitors is considered a signal for forthcoming antigenic shift. The inhibitor sensitivity of the strains for the 126 G . Kap re lyan , L . Karaivanova, N . N i k o l o v a , . . . T a b l e 3 Hemagglutinin thermostability of influenza viruses isolated in 1981-1983 Inlfuenza virus Antigenic Initial Hemagglutination titer after strains formula titer 15 min 1 30 min 60 min 120 min A V n / 3 5 ' 8 1 H 3 N 2 1/512 1:128 1:64 1:64 1:64 A V n / 6 7 / 8 1 H 3 N 2 1/256 1:128 1:128 1:64 1:32 A V n / 7 4 8 / 8 1 H 1 N 1 1/512 1:256 1:128 1:64 1:64 A V n / 6 / 8 2 H 3 N 2 1/512 1:256 1/64 1:64 1:64 A V n / 1 0 / 8 2 H 3 N 2 1/1024 1:256 1:128 1:64 1:64 A V n / 1 1 6 / 8 2 H 3 N 2 1/1024 1:256 1:128 f 1:128 1:128 A V n / 4 7 / 8 3 H 3 N 2 1/256 1:128 1:128 1:64 1:32 A V n / 1 4 3 / 8 3 H 1 N 1 1/1024 1:512 1:128 1:128 1:128 A V n / 1 4 9 / 8 3 H 1 N 1 1/256 1:128 1:64 1:64 1:64 A B r a z i l / 1 / 7 8 H 1 N 1 1/256 1:128 1:128 1:128 1:128 A T e x a s / 1 / 7 7 H 3 N 2 1/256 1:64 1:32 1:32 1:32 T a b l e 4 Results from the hemagglutination activity of influenza viruses isolated in 1931 —19S3 Anti- Hea- Initial Elution activity in saline at 37°C for Influenza virus genic ted or titer 15 min 30 min 60 min 120 min 180 min strains struc- non-ture heated HA HA • J HA HA HA HA A V n 3 / 3 / 5 / 8 1 H 3 N 2 yes 1/128 0 0 0 0 1/4 no 1/512 1/128 1/128 1/128 1/256 1/256 A V n / 6 7 / 8 1 H 3 N 2 yes 1/64 1/64 1/64 1/2 1/2 1/2 no 1/512 1/256 1/256 1/128 1/128 1/256 A V n / 7 4 8 / 8 1 H 1 N 1 yes 1/128 1/8 1/16 1/32 1/64 1/128 no 1/512 1/128 1/256 1/256 1/512 1/512 A V n / 6 / 8 2 H 3 N 2 yes 1/64 1/16 1/32 1/32 1/64 1/64 no 1/128 1/64 1/64 1/64 1/64 1/64 A V n / 1 0 82 H 3 N 2 yes 1/64 0 0 0 0 0 no 1/128 1/32 1/32 1/32 1/32 1/32 A V n / 1 1 6 / 8 2 H 3 N 2 yes 1/512 1/256 1/256 1/256 1/256 1/128 no 1/2048 1/256 1/512 1/512 1/512 1/256 A V n / 4 7 / 8 3 H 3 N 2 yes 1/128 1/2 1/4 1/8 1/8 1/8 no 1/256 1/128 1/256 1/256 1/256 1/256 A V n / 1 4 3 / 8 3 H 1 N 1 yes 1/512 1/64 1/64 1/64 1/64 1/64 no 1/1024 1/512 1/512 1/512 1/512 1/512 A V n / 1 4 9 / 8 3 H 1 N 1 yes 1/64 1/16 1/8 1/8 1/8 1/8 no 1/128 1/64 1/128 1/128 1/128 1/128 period 1981-1983 was examined by using of sera taken from humans (blood group "0"), guinea pigs, pigeons, rabbits, fowls, rats, swines, and rams. The strains w ere O n some biological properties of. 127 heterogenous concerning this property. It was to be noted that inhibitor-resistant prevailed in contrast to those isolated in the past (1972—1977) characterized as inhibitor-sensitive influenza virus strains. There were no differences in inhibitor sensitivity between the strains belonging to both serosubtypes influenza viruses type A. It is probably an expression of the interaction between the viruses of both subtypes in the course of their parallel circulation. Hemagglutinin thermosensitivity (HT) is one of the important biological properties of influenza viruses reflecting the antigenic drift. According to their different relation to chick erythrocytes after heating at 56 °C for 15 min, 30 min, 60 min, and 120 min influenza virus strains are divided into two types: with thermostable and with thermolabile hemagglutinin. Table 3 shown the results of the examination of influenza virus H T concerning the viruses isolated in our country in 1981 — 1983. A relatively good H T was established that allowed us t( i> consider the strains examined relatively thermostable. However, there was no direct ccrrelaticn between H T and antigenic structure of influenza virus strains T a b l e 5 Results from the infectious activity of influenza viruses isolated in 1981—1983 Influenza virus strains Antigenic formula Initial virus titer Infectious titer V n / 3 5 / 8 1 Vn/67 /81 A V n / 7 4 8 / 8 1 H 3 N 2 H 3 N 2 H 1 N 1 1/256 1/256 1/256 6,83 3,33 3,66 . A V n / 6 / 8 2 A V n / 1 0 / 8 2 A V n / l 16/82 H 3 N 2 H 3 N 2 H 3 N 2 1,256 1/1024 1/1024 3,0 1,66 3,66 A V n / 4 7 / 8 3 A V n / 1 4 3 / 8 3 A V n / 1 4 9 / 8 3 H 3 N 2 H 1 N 1 H 1 N 1 1/128 1/1024 1/512 3,33 4,33 3,55 isolated. It is namely a property of the strain proper and amids the strains which were recently isolated these with thermostable hemagglutinin prevail. The property elution of influenza viruses from erythrocyte surface is due to the presence of their surface antigen neuraminidase. Influenza virus strains iso-lated and studied in 1981 differed in elution properties but this variety was not related with a difference in their antigenic structure (table 4). Similar results were obtained when the next years were concerned. Most probably, hemagglutinin par-ticipates in the process of elution, too, i . e. neuraminidase is the reason for elu-tion but elution properties depend also on the strength of the link between hemag-glutinin and erythrocytes as well as on other factors. That is why namely the elution properties of the strains with different antigenic structure could not be distinguished. On table 5 the infectious activity of influenza virus strains examined during this period is presented. It varies in broad limits — from 1,66 up to 6,83 log L D 5 0 . The results show that most isolated strains possess a well-expressed infec-tious activity which is important in influenza infection dissemination. D. Kapre lyan , L . Karaivanova, N . N i k o l o v a , . . . The investigations of the pathogenic and toxic properties of influenza viruses isolated in 1981—1983 show that these properties are slightly expressed which corresponds with the clinical severity of the epidemic waves. These properties are not related with strain immunogenicity. The immunization of cocks, mice, rabbits with influenza viruses isolated by ourselves induces high-titer immune sera. This fact allows us to suggest a possibility for asymptomatic course of the influenza infection in a part of the population. The experiments for adaptation of the isolated influenza virus strains to pri­mary trypsinized cell cultures of human embryonal kidney (НЕК) and chick em­bryonal kidney (СЕК) showed a positive reaction of hemadsorption only after 2—3 passages for НЕК and after 4—5 ones for СЕК. On the basis of the results obtained the following main conclusions could he drawn: 1. Influenza virus isolation ability varies in 1981—1983 and depends on the antigenic structure and epidemic wave intensity. The percentage of isolated viruses is higher when strains with an antigenic formula A(H1N1) prevail in com­parison with that of virus type A(H3N2) circulation. 2. The study of the antigenic structure of newly-isolated influenza virus strains shows that there is still a parallel circulation of subtypes A(H1N1) and A(H3N2). There is a receding of the viruses type A(H1N1) from the standard strain A(USSR)90/77. 3. The isolated strains are characterized with well-expresed HA, H T , a re­lative inhibitor resistance and a good elution activity. There is no direct correla­tion between strain differences of biological properties and the antigenic formula. It is probably due to the interaction of both virus serosubtypes during their paral­lel circulation. 4. The infectious, pathogenic and toxic activity of the isolated strains is not high which corresponds with the dissemination and the clinical course of influenza epidemic waves in 1981—1983. These properties do not effect on the immunogenicity of the same strains that is high enough to stimulate antibody formation without any apparent manifestations in the clinical picture. R E F E R E N C E S 1. Б а р о я н , О . В . , P . А . Р в а ч е в . Bonp. еирусол., 1978, № 2 , 131 —137. — 2 . Ж Д а н о в , В . М . , С. С. Я м н и к о в а, В . А. И с а ч е н к о , и д р . Вопр. вирусол., 1981 , № 6, 657—664. — З . З а к с т е л ь с к а я , Л . Я . , З . Н и к о л о в а , М . Я х н о , и д р . Вопр. вирусол., 1982, № 6, 671—676 . — 4. М у р и , М . В а р н а , К а н д . д и с , 1982, 138 л . — 5 . Н и к о л о в а , З . , Р . К о ц е в а. Епидемиол., микробиол. и инфекц. боле­сти, 1979, № 1, 8—15. — 6. Н и к о л о в а, З . , Р . К о ц е в а, Г . К а п р е л я н , В . А р н а у д о в а , Б . М а н д у л о в , и д р . — В : Н а ц . к о н г р . и н ф е к ц . и п а р а з и т б о л е с т и , V . С о ф и я , 1982 г. Р е з ю м е т а , с . 15. — 7. J e w d w a l l , J . W . , R . G . W e b s t e r , W . U G e r h a r d . Nature, 279,- 1979, 246—248. — 8. K a p r e l y a n , G . , et a l . I n - S e m med B a l k a n . , X V I . 7—13. I X . 1980, p . 4 6 . - 9 . К б p p 1 e г, Т . , et a l . Immunobiology, 157, 1980, 320—330. — 10. К u z m о v , K - , et a l . I n : I n t e r n a t . Congr . Infec t . P a r a s i t . D i s V I I V a r n a , 1978, 1, 314—318. — 11 . L a v e r , W . G . , G . M . A i r , R . G . W e b s t e r et a l Virology, 98, 1979, No 1, 226—237. — 12. M u r i , M . , G . K a p r e l y a n . In: A te rna t . Cong r . V i r o l . , V . S t rasbourg , 1981. Pos ter session 43 , o r t h o m y x o v i r i d a e , p. 134. 128 -O n some biological properties of. 129 О Н Е К О Т О Р Ы Х Б И О Л О Г И Ч Е С К И Х СВОЙСТВАХ Г Р И П П О З Н Ы Х В И Р У С О В Т И П А А, И З О Л И Р О В А Н Н Ы Х С 1981 ПО 1983 Г. Г. Капрелян, Л. Караиванова, Н . Николова, В. Русев, А. Саръян, В . Люцканова Р Е З Ю М Е И з у ч е н а а н т и г е н н а я с т р у к т у р а и н е к о т о р ы е б и о л о г и ч е с к и е с в о й с т в а ш т а м м о в г р и п п о з ­н ы х в и р у с о в з а п е р и о д с 1981 г . по 1983 г . И з о л и р у е м о с т ь в и р у с о в н е о д и н а к о в а и п о к а з ы ­в а е т в а р ь и р о в а н и е в з а в и с и м о с т и от а н т и г е н н о й ф о р м у л ы п р е о б л а д а ю щ и х э п и д е м и ч е с к и х ш т а м м о в и и н т е н с и в н о с т и э п и д е м и ч е с к и х в с п ы ш е к . С в е ж е и з о л и р о в а н н ы е ш т а м м ы о б л а д а ю т в ы с о к о й г е м а г г л ю т и н а ц и о н н о й а к т и в н о с т ь ю , г е т е р о г е н н о с т ь ю по о т н о ш е н и ю к и н г и б и т о р -ч у в с т в и т е л ь н о с т и , а т а к ж е по о т н о ш е н и ю к т е р м о с т а б и л ь н о м у г е м а г г л ю т и н и н у . П р я м о й з а в и с и м о с т и м е ж д у а н т и г е н н о й с т р у к т у р о й и з о л и р о в а н н ы х ш т а м м о в и и с с л е д о в а н н ы м и б и о л о г и ч е с к и м и с в о й с т в а м и не б ы л о у с т а н о в л е н о . С в е ж е и з о л и р о в а н н ы е ш т а м м ы г р и п п о з н ы х в и р у с о в о б л а д а ю т х о р о ш о в ы р а ж е н н о й и н ­ф е к ц и о н н о й а к т и в н о с т ь ю и и м м у н о г е н н о с т ь ю и с л а б о в ы р а ж е н н ы м и п а т о г е н н ы м и и т о к с и ч е ­с к и м и с в о й с т в а м и , что с о о т в е т с т в у е т к л и н и ч е с к и й т я ж е с т и в с п ы ш е к э п и д е м и и в т е ч е н и е у к а ­з а н н о г о п е р и о д а . 9 Scrlpta scientiflca medica 

ON SOME BIOLOGICAL PROPERTIES OF INFLUENZA VIRUSES TYPE A ISOLATED DURING THE PERIOD 1981-1983

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ON SOME BIOLOGICAL PROPERTIES OF INFLUENZA VIRUSES TYPE A ISOLATED DURING THE PERIOD 1981-1983

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