Poultry to Human Passport: Cross-species Transmission of Zoonotic H7N9 Avian Influenza Virus to Humans

Abstract

Human infections with H7N9 avian influenza virus were first reported in the early spring of 2013, in the Yangtze-delta region of China. This virus subsequently caused five successive epidemic waves from 2013 to 2018 with highest reported cases in the last wave making this strain the most successful zoonosis influenza virus in humans in recent decades. No H7N9 human infections have been reported since 2019, probably because of the extensive vaccination of poultry. Although zoonoses of H7N9 and other subtypes of avian influenza viral infections remain rare, the virus could acquire sufficient mammalian adaptive mutations to allow it to cause a future influenza pandemic. Here, we summarize the main findings on viral and host factors affecting the interspecies transmission of the H7N9 avian influenza virus.

A dominant internal gene cassette of high pathogenicity avian influenza H7N9 virus raised since 2018

“…The K526R mutation enhances viral replication when combined with E627K [ 32 ]. The strains after 2018 mainly had alanine at a position 100 of PA, which is a human relevant amino acid (usually V in avian, A in human) [ 33 , 34 ]. However, some strains had threonine at this position, implying host adaptation to avian species around 2018.…”

Emergence, Evolution, and Biological Characteristics of H10N4 and H10N8 Avian Influenza Viruses in Migratory Wild Birds Detected in Eastern China in 2020

“…In the past 2 decades, emerging and reemerging animal influenza viruses and other zoonoses have posed major challenges to public health worldwide ( 48 – 51 ). Widely circulated wild-bird AIVs can be introduced into domestic poultry by migratory birds and domestic waterfowl, thereby increasing the risk of cross-species transmission between birds and mammals.…”

Genetic Analysis of a Novel H16N3 Virus Isolated from a Migratory Gull in China in 2021 and Animal Studies of Infection

“…Avian influenza viruses are classified into 16 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes according to differences in antigenicity and genetic profiles. To date, several important subtypes, mainly H5N1, H5N6, H5N8, H7N7, H7N9, H9N2, H10N3, and H10N8, which originated in wild birds or poultry have caused substantial economic losses to the poultry industry and pose an increasing threat to human health ( 1 – 8 ). Identification and characterization of novel subtypes of avian influenza viruses that emerge in migratory birds will guide early warnings about the risks of cross-species infection and transmission of such viruses.…”