ANALYSIS OF PANDEMIC INFLUENZA IN RUSSIA AS A PART OF THE GLOBAL PROCESS BASED ON DATA OF AN INFLUENZA MONITORING REFERENCE CENTER

Aim. Characterization of features of influenza pandemic development in Russia in relation to global process. Materials and methods. Pandemic monitoring was performed by using results of integrative analysis of laboratory diagnostic and population morbidity data from 49 supporting bases of Federal center of influenza from various cities in Russian Federation. Isolation of influenza virus was carried out in MDCK cells and chicken embryos under BSL-3 conditions. Reference virus A/California/07/09 obtained from CDC (Atlanta, USA) and antisera against this strain contained in WHO kit were used for antigenic analysis; rat antisera, new monoclonal antibodies against pandemic influenza virus developed by Research institute of influenza were also used. Results. Based on PCR monitoring during epidemic peak, rate of pandemic influenza identification reached 45-49% of examined patients. About 53% of lethal cases of respiratory infections were caused by pandemic influenza virus, while predominately young people died from pneumonia and acute respiratory distress syndrome. Russian isolates generally were antigenically and genetically similar to the parent pandemic strain — influenza virus A/California/07/09, but contained S203T substitution in hemagglutinin. A number of strains contained D222G mutation that is responsible for the expansion of substrate specificity, as well as strain specific substitutions in hemagglutinin and neuraminidase molecules. The investigated isolates were resistant to remantadin, but sensitive to oseltamivir. Conclusion. Due to the formation of population immunity after the end of the first pandemic wave new drift variants of the virus capable of overcoming this formed immunity should be expected that apparently will require the correction of vaccine composition for the 2011 — 2012 season.

influenza, pandemic, laboratory monitoring, PCR diagnosis, virus, population immunity