Infectious Diseases 2018

Infectious Diseases 2018

Evolution of H7N9 HP viruses in China in 2017

Shi et al., 2018, Cell Host & Microbe 24, 1–11 28 September, 2018

H7N9 low pathogenic influenza viruses emerged in China in 2013 and mutated to highly pathogenic strains in 2017, resulting in human infections and disease in chickens. To control spread, a bivalent H5/H7 inactivated vaccine was introduced in poultry in September 2017. To monitor virus evolution and vaccine efficacy, a group of researchers collected 53,884 poultry samples across China from February 2017 to January 2018. H7N9 HPAI viruses evolved into different genotypes. Genetic analysis of highly pathogenic strains revealed nine genotypes, one of which is predominant and widespread and contains strains exhibiting high virulence in mice. Additionally, some H7N9 and H7N2 viruses carrying duck virus genes are lethal in ducks. Thus, although vaccination reduced H7N9 infections, the increased virulence and expanded host range to ducks pose new challenges.