[Detection of antibodies to A/H5N1 influenza virus in citizens of Russian Federation].

AIM: To determine levels of antibodies to influenza virus A/H5N1 in serum samples of people living in different regions of Russia in order to assess the risk of infection with avian influenza H5N1. MATERIALS AND METHODS: Two thousand one hundred sixty-eight serum samples were tested by hemagglutination inhibition assay for the presence of antibodies to influenza virus A/H5N1. RESULTS: Twenty-six serum samples obtained from residents of Khanty-Mansiysk Autonomous Area and 2 samples from residents of Novosibirsk region were positive for antibodies to serotype A/H5. There were no clinical cases of avain influenza A/H5N1 infection in medical history of studied persons. CONCLUSION: Since cases of asymptomatic carriage of A/H5N1 influenza virus in water birds are described and ability of the virus to survive in water environment for a long time is shown, it seems logical to detect antibodies to influenza virus A/H5 in sera of subjects living in Russian Federation taking into account that influenza virus A/H5N1 is isolated from wild fowl and poultry since 2005.

[Characteristic of high pathogenic avian influenza virus subtype H5N1 isolated from common gull (Larus canus)].

AIM: To study biological characteristics of H5N1 influenza virus isolated from common gull on south of West Siberia in 2006. MATERIALS AND METHODS: Isolation and characterization of biological characteristics performed according to recommendations of World Health Organization. RESULTS: Influenza virus A (H5N1) was first isolated from common gull (Larus canus) in Russia. Antigen of isolated virus had significant affinity to polyclonal sera obtained against high pathogenic avian influenza viruses H5N1 circulating in South-East Asia. Phylogenetic analysis of isolated strain revealed its belonging to group of Qinghai-related variants of H5N1 influenza virus. Aminoacid structure of hemagglutinin proteolytic cleavage site is characteristic for type A high pathogenicity avian influenza viruses. Experimental infection of chickens demonstrated high pathogenicity of the isolated virus. CONCLUSION: Involvement of common gulls in circulation of subtype H5N1 influenza virus is demonstrated for the first time. Important role of species from Laridae family in unprecedented spreading of H5N1 influenza virus started in 2005 is discussed.

[Monitoring for influenza in population of Western Siberia in 2007-2009].

AIM: To analyze influenza viruses isolated in the 2008-2009 autumn-winter season, and to test sera collected in the south of Western Siberia during the beginning and the end of the epidemic seasons from 2007 until the A/H1N1 pandemic. MATERIALS AND METHODS: Total 149 clinical samples were analyzed and 2190 blood sera were tested. During the 2008-2009 season 17 influenza viruses were isolated. 9 of these were A/H1N1, 5-were A/H3N2, and 3 were influenza B viruses. The nucleotide sequences and amino acid composition of influenza A virus hemagglutinin (HA) were compared with reference strains. RESULTS: Among A/H1N1 viruses circulating in Novosibirsk region three viruses contained four amino acid replacements in antigen sites Ca, Cb and Sb. In A/ H3N2 viruses from Novosibirsk, 2 amino acid substitutions were detected in antigen sites B and E. CONCLUSION: Based on genotyping influenzae epidemic on February to April of 2009 in the south of western Siberia was associated with influenza viruses A/H1N1, A/H3N2, and B. All A/H3N2 influenza virus isolates were variants of reference A/Brisbane/10/2007(H3N2) and A/ H1N1 influenza viruses isolates were similar to reference A/Brisbane/59/2007(H1N1).

[Monitoring of antibodies to influenza A virus in populations of different regions of West Siberia].

AIM: To study levels of antibodies to influenza virus in sera of subjects residing in different regions of West Siberia in order to assess the risk of infection with avian influenza virus H5N1. MATERIALS AND METHODS: Two hundred and sixty-five serum samples were tested for the presence of antibodies to influenza virus A/New Caledonia/99 (H1N1), A/New York/55/2005 (H3N2), A/Whooper swan/ Mongolia/244/2005 (H5N1) by hemagglutination inhibition assay (HAI) and reaction of microneutralization. RESULTS: All tested sera were negative for antibodies to H5N1. 14.2% and 44.1% of sera were positive for antibodies to H1N1 in HAI and reaction of microneutralization respectively. In respect of antibodies to H3N2 virus, the proportion of positive sera was higher--40.3% and 76.2%, respectively. CONCLUSION: Results of such studies are very actual, especially during pandemic threat. Furthermore, such information allows to better predict consequences of seasonal influenza epidemics caused by serotypes circulating at the present time.

[Hemagglutination inhibition test for retrospective diagnosis of avian influenza in mammals].

AIM: To compare usage of native and formalinized erythrocytes from different animal species in hemagglutination inhibition (HI) test for detection of level of specific antibodies to H5N1 influenza virus in sera of mammals. MATERIALS AND METHODS: Level of anti-H5 antibodies to influenza H5 control antigen and to influenza viruses A/Common gull/Chany/2006 (H5N1), A/duck/Tuva/01/06 (H5N1), A/Anas platyrhynchos/Chany Lake/9/03 (H5N3) was determined by hemagglutination inhibition test in two influenza A (H5) reference antisera as well as in ferret antisera to native strains of avian influenza virus. Equine, rhesus macaque, sheep, guinea pig, goose, and chicken erythrocytes were used. RESULTS: Using reference antisera, H5 hemagglutinin was detected in all tested antigens with all used erythrocytes. While testing ferret antisera in HI test with reference antigen, anti-H5 antibodies were not detected or detected in extremely low titre (1/80) and only with equine erythrocytes. In most cases, titers of anti-H5 antibodies in HI test with formalinized erythrocytes were higher than with native ones. CONCLUSION: During monitoring for antibodies to H5N1 avian influenza virus in human population it is necessary to use native strains of A/H5N1 along with reference antigen. It is possible to use formalinized equine, rhesus macaque, goose, and chicken erythrocytes.