Detection of a novel chicken flu virus with pandemic potential

International public well being continues to be threatened by zoonotic and pandemic influenza. The virus has a excessive mutation fee, owing to its interspecies transmissibility and adaptableness. The influenza A virus has numerous avian and animal origins with a number of viral subtypes; these in aquatic birds differ in neuraminidase (N1-N9) and hemagglutinin (H1 – H16). 

Subtypes H6 and H9 of the influenza A virus infect recreation birds like pheasants, quails, and home chickens. H9N2 viruses containing acquired neuraminidase (NA) and hemagglutinin (HA) genes generate H5N1, H5N6, H10N8, and H7N9 viruses which will infect poultry and thereby threaten one other zoonotic outbreak and onset of a pandemic.

The examine

A latest virological examine revealed within the Rising Infectious Illnesses journal recognized the novel influenza A virus (H3N8) in reside poultry in Hong Kong, genetically much like the zoonotic H3N8 viruses reported in mainland China with its origin akin to H5N1, H5N6, H10N8, and H7N9 viruses. As well as, a danger evaluation strategy has been described to estimate the consequences of human age stratified immunity in a inhabitants.

Research: Novel Zoonotic Avian Influenza Virus A(H3N8) Virus in Rooster, Hong Kong, China. Picture Credit score: krugloff / Shutterstock


The examine entailed virologic surveillance between December 2021 and March 2022. Influenza A(H3N8) virus was recognized in samples collected from 4 farms (A-D) within the examine period. All 4 farms have been serologically optimistic for previous H3N8 infections. Consequently, the caretakers have been suggested to disinfect their farms completely and strengthen their biosecurity measures. Observe-up testing was performed in Could 2022 and once more on the finish of June 2022; all 4 farms examined damaging for the influenza A(H3N8) virus.

Between January and June 2022, many swab samples of consuming water from poultry cages, defeathering machines, fecal droppings, and chopping boards have been sampled from stalls and markets. One swab specimen from a defeathering machine and one chopping board from two totally different reside poultry markets have been H3N8 optimistic. DNA barcoding decided that the virus detected within the swab specimens originated from home chickens.

Full-genome phylogenetic evaluation of the remoted influenza A (H3N8) viruses revealed a detailed relationship between H3N8 viruses remoted from farms and poultry markets and an H3N8 viral pressure implicated within the zoonotic outbreak in mainland China. The polymerase acidic, nonstructural protein, NA, polymerase primary 1 and a pair of, and M gene segments have been similar to the G57 sublineage of the H9N2 virus present in mainland China. The sequences of the HA gene have been derived from the Eurasian avian H3 lineage, which is present in wild birds and geese.

Phylogenetic analysis of influenza A(H3N8) viruses isolated from chicken farms, live poultry markets, and the Mai Po Wetlands, Hong Kong, China (bold). A) Hemagglutinin gene segment; B) neuraminidase gene segment; C) polymerase basic 2 gene segments. Strains were analyzed with other relevant virus sequence data available in public databases (accession numbers in Appendix Table). Trees were generated by using IQ-tree ( with the general time reversible plus gamma model. Bootstrap values >80% are shown. Scale bars indicate estimated genetic distances.

Phylogenetic evaluation of influenza A(H3N8) viruses remoted from rooster farms, reside poultry markets, and the Mai Po Wetlands, Hong Kong, China (daring). A) Hemagglutinin gene section; B) neuraminidase gene section; C) polymerase primary 2 gene segments. Strains have been analyzed with different related virus sequence knowledge obtainable in public databases (accession numbers in Appendix Desk). Timber have been generated by utilizing IQ-tree ( with the final time reversible plus gamma mannequin. Bootstrap values >80% are proven. Scale bars point out estimated genetic distances.

NA gene sequence of H3N8 in poultry A was from the North American lineage. Alternatively, the N8 NA sequence detected by DNA barcoding of a virus from a fecal specimen in Hong Kong in 2018 was derived from Northern pintail duck or Anas acuta. 

Two H3N8 viruses from fecal dropping samples from Hong Kong have been associated to the Northern shoveler duck or Anus clypeata; these strains have been unrelated to rooster H3N8 in all gene segments. A similarity was discovered between the N8 gene section sequence and the H3N8 virus from different aquatic birds in mainland China. Aside from the N8 NA gene section, no different gene segments detected in poultry Influenza A(H3N8) virus have been from the wild chicken H3N8 virus from Hong Kong.

Referencing was carried out of HI titers with the World Well being Group (WHO) antiserum to A/Switzerland/8060/2017 in opposition to A/rooster/MKT-AB13cp/2020 H3N8 virus and on evaluating with the A/Switzerland/8060/2017 homologous virus. Restricted antigenic cross-reactivity was famous among the many novel avian influenza A(H3N8) virus and the seasonal human H3N2 viruses. 

The general seroprevalence was insignificant in human serum samples stratified by age. In distinction, excessive seroprevalence in the identical serum samples was noticed in a latest seasonal influenza A (H3N8) virus in people.

Herd immunity is a vital parameter when assessing any pandemic risk of zoonotic origin.


In accordance with the examine, the influenza (AH3N8) virus has been detected amongst poultry in Hong Kong. This virus would possibly pose a critical zoonotic and pandemic risk. Due to this fact, it is strongly recommended that poultry surveillance for this virus be enhanced, a complete danger evaluation be performed, and pandemic seed vaccine strains be ready if crucial.