The H5N1 avian influenza virus, widely known as bird flu, has been causing outbreaks among dairy cows in the United States since March 2024. Now, scientists studying the adaptation of H5N1 avian influenza viruses to cows have found that some of the new variants are better able to infect cow cells and tissues than some older variants, UNN reports with reference to Phys.org.
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The study, published in Nature Communications and conducted by scientists from the MRC-University of Glasgow Centre for Virus Research, examined a large panel of viruses representing over 60 years of H5N1 evolution. The researchers say their findings highlight the urgent need for continued testing and monitoring, especially as the virus continues to spread among dairy cattle and remains a potential pandemic threat.
The detection of H5N1 in cows in the spring of 2024 came as a big surprise, as influenza viruses were previously not thought to cause disease outbreaks in cattle. However, the H5N1 virus is known for its ability to spread among mammals, raising concerns about its further spread to other animal species. As the virus continues to circulate and adapt among mammals, there is a risk of new strains emerging that are better able to infect humans. This emphasizes the importance of continuous surveillance of domestic animals, including livestock.
The study showed that the ability of H5N1 viruses to infect cow cells and mammary gland tissues is not controlled by a few viral genes and depends on changes that the viruses have gradually acquired over time. The researchers also found that avian influenza viruses vary greatly in their ability to replicate in cow cells. This means that some avian influenza viruses may already be closer than others to being able to infect cattle and possibly other mammals.
Professor Pablo Murcia from the MRC-University of Glasgow Centre for Virus Research said: "Influenza viruses are constantly changing, and this rapid evolution allows them to infect new animal species. The better they adapt to infecting mammals, the more likely they are to infect and adapt to humans – as we saw during the 2009 swine flu pandemic."
Professor Massimo Palmarini from Erasmus Medical Center and the MRC-University of Glasgow Centre for Virus Research added: "Our work shows that different avian influenza viruses have very different abilities to infect cow cells and tissues. While the strain currently circulating among cattle in the US is certainly the most adapted at the moment, there are other avian viruses that could potentially infect cows if given the opportunity."