[The Epoch Times, September 26, 2023](Epoch Times reporter Lin Xu reported) There were cases of human infection with the H3N8 avian influenza virus in China in 2023. In March this year, a patient died of pneumonia after being infected.most recent itemResearchIt shows that the human H3N8 avian influenza virus can be transmitted through the air among ferrets, which is only one step away from breaking the barrier of human-to-human transmission. Close attention is needed.
According to the well-known scientific journal Cell, researchers used laboratory-grown human respiratory organoid models to study the ability of the H3N8 virus to infect humans. The results show that H3N8 virus can infect and replicate in human tracheal epithelial cells and alveolar epithelial cells, and the infection ability of human-derived viruses is significantly stronger than that of chicken-derived viruses, and it can cause severe pneumonia and viral encephalitis.
In mammalian models, although the chicken-derived H3N8 virus can infect ferrets, it cannot be effectively transmitted between ferrets, while the human-derived H3N8 virus can be effectively transmitted by contact between ferrets, and can form aerosols in the air through the virus. Medium spread, indicating that the H3N8 avian influenza virus can quickly adapt to mammalian hosts and cause infection.
Deep sequencing analysis shows that the virus can rapidly undergo “genetic tuning” and accumulate adaptive mutations after spreading among ferrets. The H3N8 avian influenza virus can quickly mutate in the human host after infecting the human body, and has the potential to spread between humans.
The H3N8 avian influenza virus cannot currently be transmitted between humans due to insufficient acid stability of the hemagglutinin (HA) protein. The human upper respiratory tract environment is acidic. In this environment, it is difficult for the hemagglutinin of the H3N8 avian influenza virus to infect respiratory cells. Researchers believe that once the virus’s hemagglutinin protein mutates and becomes more stable in an acidic environment, the risk of a large-scale outbreak will be greatly increased.
Existing influenza vaccines are ineffective against H3N8 viruses
The researchers sampled and tested 30 people who had received the trivalent influenza vaccine and 394 people in the general population. The results showed that the population generally lacks antibodies against the new H3N8 virus, and the seasonal H3N2 influenza vaccine is ineffective against the H3N8 virus. .
It is worth noting that poultry H3 subtype influenza viruses are mainly prevalent in the cold seasons of winter and spring, overlapping with the epidemic time of human seasonal influenza viruses. If the two viruses co-infect humans or intermediate hosts such as pigs and minks, other new reassortant viruses that escape the protection of existing vaccine antibodies may be produced. For example, the virus “shell” is derived from H3 subtype avian influenza virus, and the “core” gene is derived from New viruses such as H1N1 or H3N2 pose the risk of becoming a pandemic.
Currently in China, the detection rate of H3N8 avian influenza virus in poultry remains high. How to deal with the pandemic risk of H3N8 and other potential new reassortant avian influenza viruses? Researchers believe that the key is to control the source, that is, to control the spread of the virus in poultry. For example, systematically carry out poultry H3 influenza surveillance to understand the prevalence of the virus in animal groups.
From 2022 to 2023, three cases of human infection with the H3N8 virus were reported in mainland China. In April 2022, the first human infection with the H3N8 avian influenza virus was reported in Henan Province, China. The patient was a 4-year-old boy who developed acute respiratory distress syndrome and later recovered; in May 2022, a 5-year-old boy in Hunan Province After being diagnosed, he developed symptoms of mild fever, chills, sore throat and runny nose, which disappeared after 7 days. In March this year, a 56-year-old woman in Guangdong Province was hospitalized with severe pneumonia after being infected with the H3N8 avian influenza virus, and eventually died.
The research team previously published the article in “The Lancet Microbe”Traceability researchIt was found that the new H3N8 virus that causes human infection was first discovered in a chicken farm in Guangdong in December 2021, and then appeared in many provinces in China. Sequence analysis showed that the virus had undergone multiple recombinations. @
Editor in charge: Zhang Xiaohui
2023-09-27 11:26:24
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