This Week in Virology TWiV 1259: Capricious flu and a tickborne clue
Oct 5, 2025
Explore the intriguing world of avian H5N1 influenza as hosts discuss its transmission in goats and the implications for public health. Discover the cellular receptor identified for tick-borne encephalitis virus, revealing new insights into viral entry mechanisms. The show also touches on public trust in science and the recent culling of H5N1-infected ostriches in Canada. Plus, listen to unique listener letters addressing vaccine policy, measles outbreaks, and study picks about cosmic discoveries!
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Clade 2.3 H5N1 Expanded Host Range
- Clade 2.3.4.4b H5N1 viruses expanded host range and now infect diverse mammals including dairy cows and goats.
- These viruses persist year-round and pose reservoirs that can move between birds, livestock, and humans.
Mammary Glycans Enable Avian H5 Replication
- Goat and cow mammary glands express abundant avian-type alpha-2,3 sialic acids enabling efficient replication of avian H5 hemagglutinin.
- Single amino-acid changes could shift binding toward human alpha-2,6 receptors, increasing zoonotic risk.
H5N1 Causes Severe Mastitis In Goats
- Experimental infection of lactating goats with two H5N1 genotypes produced necrotizing mastitis and reduced milk quality and quantity.
- Both cow-derived and turkey vulture-derived isolates replicated to high titers in mammary tissue and transmitted to suckling kids.
