An Emerging Influenza A(H3N3) Virus in China

The world is in chaos and nature follows that path too. We've reported here about the emerging threat of the Influenza A(H5N1) virus. The epicenter of this threat is currently in the US.

But in China another Influenza virus is stirring. In 2023, a study described a new reassortant Influenza A(H3N3) Virus in Chinese poultry which included an HA gene from Influenza A(H3N8), an NA gene from Influenza A(H10N3), and some internal genes from Influenza A(H9N2), which are all zoonotic subtypes[1].

Worried, the scientists tried to infect mice with this reassortant Influenza A(H3N3) Virus, but it was not (yet) pathogenic in mice, bound preferentially to avian receptor cells, and (still) lacked a number of key mammalian adaptations.

That said, over the past few years we've seen a noticeable uptick in new H3 reassortments emerging out of China. Since all of the known human Influenza pandemics (going back 130 years) have sprung from H1, H2, or H3 Influenza viruses, we shouldn't ignore new H1, H2, or H3 viruses whenever they emerge.

A new report on this Influenza A(H3N3) Virus finds that it (and other novel H3 reassortants) is spreading like wildfire in Chinese poultry. The virus carries mutations that may '... increase viral resistance, virulence, and transmission in mammalian hosts'[2].

The Influenza virus is on the move and we should become very worried. Remember, Wisdom comes from experience. Experience is often a result of lack of wisdom.

[1] Qiuyan et al: Emergence of novel reassortant H3N3 avian influenza viruses with increased pathogenicity in chickens in 2023 in Emerging Microbes and Infections – 2023. See here.
[2] Lei et al: Evidence of an emerging triple-reassortant H3N3 avian influenza virus in China in BMC Genomic - 2024. See here.