How the H5N1 virus invades the mammary glands of dairy cattle
A newly published study in National Science Review by researchers from the Harbin Veterinary Research Institute, China, provides critical insights into the infection mechanism of the H5N1 avian influenza virus in dairy cattle and potential strategies for disease prevention.
The study demonstrates that H5N1 infects the mammary glands of dairy cows not through conventional respiratory transmission, but via a unique “mouth-to-teat” route. This mode of transmission occurs when calves or cows suckle from others or from themselves, a behavior commonly observed in dairy herds. The researchers found that oral tissues, udders, and mammary glands express receptors compatible with avian influenza virus, facilitating viral entry and replication.
In experimental challenge studies, vaccination with either an inactivated vaccine or a DNA vaccine based on the HA protein of clade 2.3.4.4b conferred complete protection against infection, even under conditions simulating exposure to contaminated milking equipment. In vaccinated animals, the virus was not detected in milk, mammary tissues, or the respiratory tract, and no clinical signs were observed.
