Isolation and characterization of influenza C viruses in the Philippines and Japan

ODAGIRI T, Matsuzaki Y, Okamoto M, Suzuki A, et al. Isolation and characterization of influenza C viruses in the Philippines and Japan. J Clin Microbiol. 2014 Dec 31. pii: JCM.02628.
submited by kickingbird at Jan, 4, 2015 15:39 PM from J Clin Microbiol. 2014 Dec 31. pii: JCM.02628.

From November 2009 to December 2013, 15 influenza C viruses were isolated, using MDCK cells, from specimens obtained from children with severe pneumonia and influenza-like illness (ILI), in the Philippines. This is the first report of influenza C virus isolation in the Philippines. In addition, from January 2008 to December 2013, 7 influenza C viruses were isolated from specimens that were obtained from children with acute respiratory illness (ARI) in Sendai city, Japan. Antigenic analysis with monoclonal antibodies to the hemaggultinin-esterase (HE) glycoprotein showed that 19 strains (12 from Philippines and 7 from Japan) were similar to the reference strain C/Sao Paulo/378/82(SP82). Phylogenetic analysis of the HE gene showed that strains from the Philippines and Japan formed distinct clusters within an SP82-related lineage. The clusters including the Philippine and Japanese strains were shown to have diverged from a common ancestor around 1993. In addition, phylogenetic analysis of internal genes showed that all strains isolated in the Philippines and Japan had emerged through reassortment events. The composition of the internal genes of the Philippine strains was different from that of the Japanese strains, although all strains were classified into an SP82-related lineage by HE gene sequence analysis. These observations suggest that the influenza C viruses analyzed here had emerged through different reassortment events; however, the time and place at which the reassortment events occurred could not be determined.