Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

The substantial increase in prevalence and emergence of antigenically divergent or highly pathogenic influenza A(H7N9) viruses during 2016-17 raises concerns about the epizootic potential of these viruses. We investigated the evolution and adaptation of H7N9 viruses by analyzing available data and newly generated virus sequences isolated in Guangdong Province, China, during 2015-2017. Phylogenetic analyses showed that circulating H7N9 viruses belong to distinct lineages with differing spatial distributions. Hemagglutination inhibition assays performed on serum samples from patients infected with these viruses identified 3 antigenic clusters for 16 strains of different virus lineages. We used ancestral sequence reconstruction to identify parallel amino acid changes on multiple separate lineages. We inferred that mutations in hemagglutinin occur primarily at sites involved in receptor recognition or antigenicity. Our results indicate that highly pathogenic strains likely emerged from viruses circulating in eastern Guangdong Province during March 2016 and are associated with a high rate of adaptive molecular evolution.

Original publication

DOI

10.3201/eid2410.171063

Type

Journal article

Journal

Emerg Infect Dis

Publication Date

10/2018

Volume

24

Pages

1795 - 1805

Keywords

China, H7N9, adaptation, avian influenza, avian influenza virus, diversity, hemagglutination inhibition assay, influenza, molecular epidemiology, molecular evolution, phylogenetics, respiratory infections, virus subtypes, viruses, Amino Acid Sequence, Animals, Antigenic Variation, Birds, China, Evolution, Molecular, Genetic Variation, Genome, Viral, Genotype, Geography, Medical, History, 21st Century, Humans, Influenza A Virus, H7N9 Subtype, Influenza in Birds, Influenza, Human, Phylogeny, RNA, Viral