[Internal epidemic influenza virus proteins: isolation and investigation].

The internal influenza virus proteins M1 and RNP free from surface protein impurities were isolated from subviral particles (virions free from HA and NA ectomenes). The spikeless particles had no propensity to aggregate in the solution at pH 5.0 as compared with native viruses. The subviral particles of B/Hong Kong/330/01 influenza virus, which belonged to B/Victoria/2/87-lineage, were obtained by proteolytic treatment with the enzyme bromelain under the same conditions as in cases of influenza B viruses of B/Jamagata/16/88 lineage. A chromatographic analysis of the tryptic hydrolyzates obtained for matrix (M1) proteins of A(H1N1) and A(H3N2) influenza viruses revealed differences that were greatest between the protein M1 molecules isolated from influenza viruses of different subtypes of hemagglutinine. These findings suggest there are variations in the structure of this conservative internal viral protein M1 during evolution.

[Characterization of epidemic influenza virus A(H3N2) strains circulating in Russia in the 2003-2004 epidemic season].

Studies indicated that the epidemic rise in the incidence of influenza was caused by its virus A (H3N2) circulation in Russia in the 2003-2004 season. The Center of Influenza Ecology and Epidemiology investigated 101 epidemic strains isolated the MDCK culture. Antigenic analysis showed that all viruses A(H3N2) were similar to the reference virus A/Fujian/411/02(H3N2) and only 5 strains slightly differed from the latter. Twelve (14%) strains resistant to rimantadine at a concentration of 0.5 mg/ml were identified. Investigation of paired sera from the patients demonstrated a rise of antibodies to the references of influenza virus A(H3N2) in 68.7% of cases and a less increase in those to influenza viruses A(H1N1) and B. The active circulation of A(H3N2) viruses was due not only to changes in their antigenic structure, but also to the low level of antibodies to these viruses, as shown by the analysis of donor sera.

[The properties of the epidemic influenza viruses A and B strains circulating in Russia in the 2004-2005 epidemic season].

The epidemic upsurge of influenza morbidity in Russia in 2004-2005 was caused by the active circulation of influenza A(H3N2) and B viruses. A hundred and sixty-six epidemic strains were studied. All the strains were isolated in the MCK cell culture. Influenza A(H3N2) viruses (n=77) were antigenic variants of the reference A/Fujian/411/ 2002 and A/California/7/2004 strains. Three influenza A(H1N1) viral strains that were antigenic variants of A/New Caledonia/20/99 strains were isolated in sporadic cases. Influenza B virus strains (n=83) were antigenic variants of the reference B/Shanghai/361/02--lineage B/Yamagata/l6/88. In addition, 3 antigenic variants of B/Hong Kong/ 330/2002 (lineage B/Victoria/2/87) strains were isolated. Nine (20%) strains resistant to rimantadine at a concentration of 5 microg/ml were identified. Chromatographic analysis of B/Shanghai/361/02 and BIHong Kong/330/01 viral protein M1 trypsin hydrolysates revealed differences in the profiles of chromatograms of influenza A virus proteins M1. Examination of 121 pair sera from patients revealed an increase in antibodies to influenza A(H3N2) viruses in 10-21% of cases and to influenza B viruses in 20-36% of cases.