Avian H5N1 influenza virus may use cow udders as an infectious route

Scientists have detected a highly pathogenic H5N1 influenza virus strain in cow’s milk, suggesting that flu may be able to travel from udder to udder. A study led by Stacey Schultz-Cherry, PhD, St. Jude Department of Host-Microbe Interactions, established a mouse model to investigate H5N1’s ability to infect mammary tissue through intraductal inoculation. H5N1, but not H1N1 virus, was able to replicate in mouse mammary epithelium, indicating that H5N1 may have gained the ability to infect these tissues through this novel exposure route. The findings were published in the Journal of Virology. 

“The H5N1 emergence in dairy cows led to many questions about virus spread, especially given the limited infection of the respiratory tract — the typical route of transmission. We and others hypothesized that milking machines could be transmitting the virus through the udders, i.e., intraductal inoculation. Our study shows that this could be a unique route of infection and provides a model to test therapeutic strategies to block further transmission,” said Schultz-Cherry.

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