The evolutionary dynamics of chicken-origin H6N2 viruses isolated in South Africa between 2002 and 2013 were investigated. Sub-lineages I and II continued to co-circulate under vaccination pressure, but sublineage I, from which the inactivated vaccine was derived, displayed a markedly higher mutation rate and a three-fold increase in the emergence of potential antigenic sites on the globular head of HA compared to sub-lineage II. Immunological pressure culminated in a critical phenotypic change as four of the five isolates from 2012-2013 had lost the ability to haemagglutinate chicken erythrocytes, correlating with a pattern of predicted O-glycosylation sites at residues 134, 137 and 141 within the critical 130 loop of the receptor binding domain site. Coassortment of the HA, NA and M genes in the respective sub-lineages contrasted reassortment of the other internal protein genes, and the vaccine seed strain itself was the probable donor of segments to sub-lineage II field strains.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.