Molecular and antigenic characterization of H6N2 avian influenza viruses isolated in South Africa

Abstract

"Does the current H6N2 vaccine still offer sufficient protection?" is a fundamental question asked by the poultry industry in South Africa today. In this study we advanced our understanding of the genetic drift of the H6N2 virus in poultry in South Africa, by phylogenetic analyses of gene segments and antigenic characterization of the virus, and determined the efficacy of the current vaccine. Using isolates collected between 2002 and 2013, full genome sequencing was performed to determine whether genetic re-assortment had occurred over the past decade. Vaccine batches were made from these isolates and with the use of antigenic cartography the haemagglutination inhibition (HI) data was visualized to determine antigenic similarities or differences between the viruses. From this research, information about the evolution of the H6N2 virus was revealed. The findings show that although extensive genetic drift has occurred over the last ten years and two distinct sub-lineages have developed, the current vaccine will still offer sufficient protection for both sub-lineages of H6N2 viruses. Keywords: avian influenza virus, poultry, H6N2, genetic drift