#17,518
Although HPAI H5 viruses are currently at the top of our avian flu worry list, it is far from the only influenza subtype that has pandemic potential. Between 2013 and mid-2017 the world was on edge when more than 1,500 people were infected with (LPAI & HPAI) H7N9 in China (see chart below).
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| Credit FAO |
There are others, of course. We've seen H6N1 infect dogs and jump to at least one human in Taiwan (see Study: Adaptation Of H6N1 From Avian To Human Receptor-Binding), isolated cases of H7N4 in China, and scores of (mostly mild) H9N2 infections.
While it tends to get less attention than the others, H10 viruses have also shown a proclivity for spilling over into mammals (see Avian H10N7 Linked To Dead European Seals), and occasionally, infecting humans.
In the spring of 2019, in JVI: Aerosol Transmission of Gull-Origin Iceland Subtype H10N7 Influenza A Virus in Ferrets, we looked at research that found a `. . . . gull-origin H10N7 virus can be transmitted between ferrets through the direct contact and aerosol routes, without prior adaptation.'
These researchers noted that these viruses `. . . showed high binding affinity to human-like glycan receptors. . . ', the authors recommended that avian H10 viruses be monitored closely, as they have some pandemic potential.
All of which brings us to a new study, published by One Health, that looks at the evolution of an array of avian H10 subtypes circulating in China, that also warns that they have pandemic potential. Due to its length, I've only reproduced the link, Abstract, and Conclusions.
Follow the link to read it in its entirety.
H10Nx avian influenza viruses detected in wild birds in China pose potential threat to mammals
Xinru Lv a 1, Jingman Tian b 1, Xiang Li a 1, Xiaoli Bai b 1, Yi Li a 1, Minghui Li b, Qing An a, Xingdong Song a, Yu Xu c, Heting Sun c, Peng Peng c, Siyuan Qin c, Zhenliang Zhao a, Rongxiu Qin a, Qiuzi Xu a, Fengyi Qu a, Meixi Wang a, Hua Luo a, Zhen Zhang a, Xiangwei Zeng a…Hongliang Chai
https://doi.org/10.1016/j.onehlt.2023.100515Get rights and content
Under a Creative Commons license
Highlights
• The H10Nx AIVs in wild waterfowl in China were divided into eight genotypes.• The H10 viruses showed good mammalian adaptation, posing a threat to public health.• The spatiotemporal spread of the global H10 viruses was described.• Anatidae was the key species for introducing and spreading H10 AIVs.
Abstract
H10 subtype avian influenza viruses (AIVs) have been isolated from wild and domestic avian species worldwide and have occasionally crossed the species barrier to mammalian hosts. Fatal human cases of H10N8 infections and the recent detection of human H10N3 infections have drawn widespread public attention. In this study, 25 H10Nx viruses were isolated from wild waterfowl in China during a long-term surveillance of AIVs.
We conducted phylogenetic and phylogeographic studies of the hemagglutinin (HA) genes of global H10 viruses to determine the spatiotemporal patterns of spread and the roles of different hosts in viral transmission. We found the pattern of AIV transmission from wild birds to poultry to humans, and Anatidae have acted as the seeding population in the spread of the virus. Phylogenetic incongruence indicated complex reassortment events and our isolates were divided into eight genotypes (G1–8).
We also found that the HA genes of the G8 viruses belonged to the North American lineage, indicating that intercontinental gene flow has occurred. Their receptor-binding specificity showed that the G1/4/5/6/7/8 viruses bind to both human-type α2,6-linked sialic acid receptors and avian-type α2,3-linked sialic acid receptors. Mouse studies indicated that the H10Nx isolates replicated efficiently in the respiratory system without preadaptation, but showed low pathogenicity in mice. The H10Nx isolates showed no (G2/4/7) or low pathogenicity (G1/3/5/6/8) in chickens, and the G6 and G8 viruses could be transmitted to chickens through direct contact.
The asymptomatic shedding of these wild-bird-origin H10Nx isolates in chickens and their good adaptation in mice should increase the ease of their transmission to humans, and they therefore pose a threat to public health. Our findings demonstrate a further understanding of wild bird-origin H10 viruses and provide information for the continuous surveillance of H10 subtype viruses.
5. Conclusions
During our long-term active surveillance of AIVs in migratory birds, 25 H10 subtype AIVs were isolated from Anatidae and shorebirds in China from 2013 to 2020. Our study indicated that these viruses revealed eight genotypes, reflecting the complicated reassortant and high level of genetic diversity of them. And these viruses could replicate in mice efficiently without preadaptation, and G4–8 viruses acquired the ability to bind to the human-type receptors, posing a threat to public health. The replication and transmission of the H10 viruses in chickens were limited, and its silence spread in chickens made it difficult to detect. To reduce the emergence of novel reassortant viruses and enzootic influenza viruses, the active surveillance of H10 AIVs wild birds and poultry is required. The early characterization of these viruses can reduce the potential risk of their zoonotic transmission from poultry to humans. The asymptomatic shedding of these wild-bird-origin H10Nx isolates in chickens and their good adaptation in mice should increase the ease of their transmission to humans, and they therefore pose a threat to public health.
Although it can be difficult to worry about the creek rising when your house is already on fire, these `lesser' (read: non-H5N1) viral threats deserve our attention and respect, because any one of them could make an evolutionary breakthrough and suddenly become the next big threat.
We were blindsided 2009 by swine H1N1, and again in 2019 by COVID. There's no reason to suspect it couldn't happen again.