Influenza B viruses with mutation in the neuraminidase active site, North Carolina, USA, 2010-11

Abstract

Oseltamivir is 1 of 2 antiviral medications available for the treatment of influenza B virus infections. We describe and characterize a cluster of influenza B viruses circulating in North Carolina with a mutation in the neuraminidase active site that may reduce susceptibility to oseltamivir and the investigational drug peramivir but not to zanamivir.

Figure

Phylogenetic analysis of A) hemagglutinin and B) neuraminidase genes of Victoria lineage type B influenza viruses (n = 89). Red indicates the 2010−2011 Northern Hemisphere vaccine strain; blue indicates the cluster of influenza B viruses identified in North Carolina carrying the I221V substitution in the neuraminidase; green indicates viruses collected from North Carolina with wild-type sequence at position 221 in the neuraminidase; black indicates representatives of globally circulating influenza B viruses. Month of collection is shown after virus strain designation. Evolutionary distances were computed by using the Tamura-Nei method (www.megasoftware.net/WebHelp/part_iv___evolutionary_analysis/computing_evolutionary_distances/distance_models/nucleotide_substitution_models/hc_tamura_nei_distance.htm). Scale bars indicate number of base substitutions per site.