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The kinetics of reaction between hemagglutinating antigens and immune sera to 10 hantavirus strains (7 isolated in the Primorye territory and 3 in other regions) was studied in the cross kinetic hemagglutination inhibition (KHAI) test. An A parameter is suggested for evaluation of the similarity and differences between the studied strains. This parameter helped detect antigenic differences between Hantaan and Seoul viruses and the inter-type differences between Hantaan-like strains. KHAI is more specific than HAI studies of antigenic relationships between strains of different hantavirus serotypes.

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In 1976-1979 in various regions of the USSR influenza viruses were isolated from mammals and birds and found to be antigenically similar with human influenza viruses having hemagglutinin H0, H1, and neuraminidase N1. Comparative studies of electrophoretic mobility in polyacrylamide gel of RNAs and proteins of these viruses and human influenza viruses sharing common antigens with them were carried out. By the mobility in gel of genome fragments, the virus isolated from a squirrel, A/squirrel/Vladivostok/1004/79 (H0N1), was found to be similar to human A/PR/8/34 (H0N1) virus; both viruses had a similar polypeptide composition. In contrast, the virus isolated in 1978 from a turkey, A/turkey/Kiev/292/78 (H1N1), by the mobility in gel of genome fragments including those coding for hemagglutinin and neuraminidase differed significantly from antigenically similar epidemic viruses: A/FM/1/47/ (H1N1) and a virus isolated during an epidemic in the same year, A/USSR/90/77/ (H1N1) despite the similarity with the latter in the polypeptide spectrum. Hemagglutinin of a virus isolated in 1976 from blue whales, A/whale/TO/19/76, was serologically identified as HO, neuraminidase of this virus as Nav2. An analysis of genome fragments of the whale virus showed the gene 4 coding for hemagglutinin to be similar by mobility in gel with the corresponding fragment of human influenza virus A/PR/8/34 (H0N1), and the gene 6 coling for neuraminidase in most influenza A viruses to be similar by mobility in gel with the gene 6 of A/pintail/Primorie/695/76 (H2Nav2) virus. An analysis of proteins of this virus by mobility in gel showed all its proteins, with the exception of one with a molecular weight of about 70,000 daltons, to be similar with those of human A/PR/8/34 (H0N1) virus. The protein with the molecular weight of about 70,000 daltons is assumed to be neuraminidase of the second avian type (Nav2). A similar protein was found in avian viruses A/pintail/Primorie/18/76 (H2Nav2), and A/tern/Turkmenia/18/73 (Hav7 Nav2). The antigenic analysis of these strains using a panel of 6 monoclonal antibody to the A/Brazil/11/76 (H1N1) strain revealed a close similarity in the antigenic structure of hemagglutinin of human influenza virus A/USSR/90/77 (H1N1) which had caused an epidemic outbreak in the USSR in 1977-1978 and A/turkey/Kiev/292/78 (H1N1) virus. Human and animal influenza viruses with hemagglutinin of the HO type did not react with any of the 6 clones under study.

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The hemagglutinin of an influenza virus isolated from a wild duck (Pintail, Anas acuta) in the USSR in 1976 had been found to be antigenically indistinguishable from the hemagglutinin of H2N2 viruses of human origin isolated in 1957. The hemagglutinins from viral preparations of the A/Anas acuta/Primorie/695/76 (H2Nav2) and A/Singapore/1/57 (H2N2) strains were purified by SDS gel chromatography as the subunits HA1 and HA2. Comparison of amino acid compositions and peptide maps of tryptic peptides containing [14C]-carboxymethylcysteine showed a striking degree of similarity between the H2 hemagglutinins.

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A strain A/Anas acuta/Primorie/730/76 was isolated in the autumn of 1976 from wild pintails in the Primorskiy kray, USSR, and found by the H1 and neuraminidase activity inhibition test to be antigenically related to the reference A/Hong Kong/1/68 strain. The CFT showed the A/Anas acuta/Primorie/730/76 strain to contain in its hemagglutinin 3 antigenic determinants: two common with the A/Hong Kong/1/68 strain and one the strain-specific, lacking in the human influenza viruses of the H3N2 antigenic formula.

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Recombination of a human influenza virus with an avian influenza virus produced a H2Nav2 recombinant with the antigenic properties analogous to those of avian influenza virus (H2Nav2) isolated from wild ducks in the Far East, USSR. Recombination of two avian influenza viruses yielded a recombinant H2N2, an antigenic analogues of influenza A/Singapore/1/57 (H2N2) virus which had started an epidemic of influenza in 1957.

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Limited outbreaks of influenza were reported in the far east of the U.S.S.R. early in November, 1977, and a week or two later in cities in Siberia and the European parts of the U.S.S.R. The majority of influenza-virus isolates belonged to the H1N1 subtype of influenza-A virus, though strains of the current H3N2 subtype were also isolated. A moderate epidemic of H1N1 influenza spread throughout the country in the middle of December. Mainly children over 5 years and young adults were infected.

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Four isolates of influenza virus strains from Moscow and Habarovsk that caused outbreaks of influenza in November and December 1977 in several cities of the USSR were studied and their haemagglutinins and neuraminidases were compared with those of other human and animal influenza viruses including A/whale/Pacific Ocean/76. In H1 tests these isolates, designated A/USSR/77, reacted with immune serum against A/FM/1/47 (H1N1) to the homologous titre, and with antiserum against A/whale/PO/19/76 virus to 1/8 of the homologous titre. In neuraminidase inhibition tests all A/USSR/77 isolates showed the presence of human N1 type neuraminidase, more closely related to A/sw/New Jersey/76 (Hsw1N1) than to A/FM/1/47 (H1N1) virus. The haemagglutinin of A/whale/Pacific Ocean/19/76 virus occupies an intermediate position between H0 and H1, but its neuraminidase is close to Nav2. The virus from whales multiplies better at low (28 degrees C) and at high (40 degrees C) temperatures than do the viruses of human origin that were tested.

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The discovery in migrating birds of influenzaviruses and the demonstration of relationships between strains found in man and in birds show the importance of these investigations for influenzavirus ecology. Investigation of birds in the far-east regions of the USSR is particularly important as many of them migrate to South-East Asia and China, the regions from which human influenza pandemics seem to originate. A total of 262 bird sera from these regions were titrated by the HI method with 20 different influenzavirus antigens (5 human, 2 equine, 1 swine, and 12 avian influenzaviruses). Haemagglutination-inhibiting activity was found in 16.8% of the tested sera, most frequently in sera of Anas formosa, Gallinago gallinago, Anas falcata, and Larus crassirostris. HI activity to A/turkey/Wisconsin/66 (Hav6N2) was found in 7.3% of the sera.

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