Hemagglutinin characteristics, changes in pathogenicity, and antigenic variation of highly pathogenic H7N9 avian influenza viruses in China

We read with interest a recent article about the evolutionary dynamics of H7N9 avian influenza viruses (AIVs) in mainland China in this journal. 1. Xiang D Pu Z Luo T Guo F Li X Shen X et al. Evolutionary dynamics of avian influenza A H7N9 virus across five waves in mainland China, 2013-2017. J Infect. Sep 2018; 77 (PubMed PMID: 29807090): 205-211 Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar Since 2013, five waves of the H7N9 epidemic have spread from eastern to southern and northern China. H7N9 was regarded as low pathogenic (LP) AIV in the previous four waves. In the 5th wave, some H7N9 viruses have an insertion of several basic amino acids at the HA cleavage site, which is associated with transition from low to high pathogenicity for chicken. In spite of vaccination practice, the pathogenicity and antigenicity of H7N9 high pathogenic (HP) AIVs in animal models remain unclear. In this study, we present a brief assessment of the characteristics, pathogenicity, and antigenicity of H7N9 HPAIVs in chickens and ducks.