A Chinese research team has systematically identified the origin, evolution, and propagation of the H5N1 virus, which has caused avian influenza outbreaks globally.

The research, conducted by the Harbin Veterinary Research Institute under the Chinese Academy of Agricultural Sciences, was published recently in the journal Emerging Microbes & Infections.

The study found the currently circulating H5N1 virus emerged in the Netherlands in October 2020 as an H5N8 avian influenza-virus recombination with subtypes such as H1N1 and H3N8.

The H5N1 virus was responsible for the loss of over 70 million domestic poultry in Europe, Africa, Asia, and North America since October 2020, said Chen Hualan from the Harbin Veterinary Research Institute, who led the research team.

The researchers performed a detailed phylogenic analysis of 233 representative H5N1 strains isolated from 28 countries. They found that the virus has encountered complicated gene exchange with different viruses circulating in wild birds and formed 16 genotypes since its emergence.

They isolated 13 strains of the H5N1 virus from 26,767 wild bird and poultry samples collected in China between September 2021 and March 2022.

Four genotypes of the virus, G1, G7, G9, and G10, were detected in China. Three of these were previously reported in other countries, said Chen.

Antigenicity analysis shows that the H5-Re14 vaccine strains currently used in China match well with the virus. It indicates that H5 and H7 trivalent inactivated avian influenza vaccines can effectively protect immunized poultry from the virus.

The study calls on high-risk countries to vaccinate poultry against the H5 subtype of avian influenza.