[Analysis of population immunity of residents of Russian Federation regions against seasonal and highly pathogenic strains of influenza virus].

AIM: Determine the level of antibodies against socially significant types/serotypes of influenza virus in sera of individuals residing in various regions of Russia. MATERIALS AND METHODS: 1525 samples of blood sera collected in August-December 2013 in 8 regions of Russian Federation were studied in hemagglutination inhibition reaction (HAI) with antigens obtained from A/California/07/09, (H1N1)pdm09, A/Victoria/361/2011(H3N2), B/Brisbane/60/2008 (Victoria line), B/Massachusetts/2/2012 (Yamagata line), A/Commongull/Chany/2006 (H5N1), A/Anhui/01/2013 (H7N9) influenza virus strains. RESULTS: None of the blood sera samples had significant HAI titers against A/H5 and A/H7 antigens. Of all the 1525 samples, 788 (52%) were positive with A(H1N1)pdm09 antigen; 734 (48%) reacted with A(H3N2) antigen; 1010 (66%) samples were positive with B/Victoria antigen and 602 (39%) samples were positive with B/Yamagata antigen. CONCLUSION: Healthcare institutions should pay attention to the correction of population immunity profile in regions for the reduction of social-economic losses from seasonal influenza epidemics.

[Correlation between the receptor specificity of pandemic influenza A (H1N1)pdm09 virus strains isolated in 2009-2011 and the structure of the receptor-binding site and the probability of fatal primary viral pneumonia].

The receptor specificity (RS) of pandemic influenza A(H1N1) pdm09 virus strains deposited into the State Collection of Viruses of the Russian Federation, D. I. Ivanovsky Research Institute of Virology, Ministry of Health and Social Development of Russia, in the 2009-2010 and 2010-2011 epidemic seasons to a panel of 9 sialoglycopolymers (SGP). The strains were divided into 3 groups according to the W(3/6) index proposed by the authors, which was equal to the amount of reactivities to unbranched alpha2-3-SGP to that of reactivities to unbranched alphal-6-SGP: W(3/6) < or = 1.0; 1.0 < W(3/6) < or = 1.5. The W(3/6) < or = 1.5 group showed a predominance of a2-3-RS, attended by the high incidence of fatal primary viral pneumonias (FPVP) (60.0%) and amino acid replacements in the HA1 receptor-binding site (RBS) (80.0%): D222{G, N} and Q223R. The 1.0 < W(3/6) < or = 1.5 group was characterized by mixed alpha2-3/alpha2-6-RS with the incidence of FPVP (29.7%) and amino acid replacements in the HA1 RBS (40.5%) (D222{G, N, V} and Q223), respectively. In the W(3/6) < or = 1.0 group, alpha2-6-RS was prevalent, FPVPs were absent and amino acid replacements in HA1 RBS (D222{G, E}) were seen only in 6.0% of cases. The number of strains with increased specificity to alpha2-3-sialosides increased in the 2010-2011 epidemic season as compared to the previous season. With their further spread among the population, there may be a rise in cases of severe primary viral pneumonias with possible fatal outcomes, which can be, however, accompanied by a decrease in the capacity of mutants to air-dropwise transmission.

[A possible association of fatal pneumonia with mutations of pandemic influenza A/H1N1 sw1 virus in the receptor-binding site of the HA1 subunit].

The paper gives the results of sequence analysis of 150 positive samples in real-time RT-PCR, including 47 autopsy materials from patients (including 10 pregnant women), who died from fatal pneumonia mainly in November-December 2009, in whom the lifetime etiological diagnosis had not been made and hence no early etiotropic therapy performed. 70% of the primary materials from the deceased patients were found to have pandemic influenza A(H1N1) v mutants in the lung tissue with D222G (15%), D222N (15%), D222E (2%) substitutions, as well as a mixture of mutants (38%). Nasopharyngeal lavages from 3 Chukotka deceased patients exhibited only consensus (nonmutant) D222 virus variants; there was a mixture of consensus and mutant virus variants in the trachea and a mixture of mutant ones in the lung. Preliminary data from the study of the interaction of the hemagglutinin of two strains having D222G and D222N mutations with 9 oligosaccharides imitating the variants of cell receptors for influenza A virus suggest that there is a double receptor specificity for alpha2'-3' and alpha2'-6'-sialosides with a preponderance of alpha2'-3'-specificity. Further spread of the mutants that have acquired a high virulence and preserved their capacity for the respiratory route of human infection may lead to the situation similar to that seen in the 1918-1919 pandemic. Another scenario for evolution of the virus is to preserve its receptor specificity for alpha2'-3'-sialosides and high virulence with losses of alpha2'-6' specificity and capacity for aerosol transmission, by damping the pandemic.

[Trends in the spread of pandemic influenza A(H1N1) swl in the Far East in 2009].

The paper describes the trend in the spread of pandemic influenza A(H1N1) swl virus in the Far East, which started in this region 2-3 months later than that in the European part of Russia. By mid-October seasonal epidemic influenza was practically displaced by pandemic one.