Dynamics of H5N1 Clade 2.3.4.4b in infected cattle
A peer-reviewed paper titled 'H5N1 Clade 2.3.4.4b Dynamics in Experimentally Infected Calves and Cows' explores the behavior of the highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b H5N1 in cattle. The research involved two independent experimental infection studies: one assessing oronasal susceptibility and transmission in calves, and the other examining the susceptibility of lactating cows following direct mammary gland inoculation. Calves inoculated with the H5N1 B3.13 strain exhibited moderate nasal viral replication and shedding but did not display severe clinical signs or transmit the virus to sentinel calves. In lactating cows, intramammary inoculation led to severe mastitis, high fever, and a significant reduction in milk production. High titers of the virus were detected in milk, with viral shedding continuing for at least eight days, though no nasal shedding or systemic infection was observed. The study also noted the emergence of adaptive mutations in the virus, indicating its potential for further adaptation to mammalian hosts. The findings suggest that milk and milking procedures are likely the primary routes of H5N1 transmission between cattle, rather than respiratory spread.
