Narrative review reveals host-range expansion and milk-borne shedding of H5N1 avian influenza in dairy cattle, highlighting unprecedented transmission routes across mammalian species.
Key Points
Examine the molecular determinants, epidemiological shifts, and transmission implications of highly pathogenic avian influenza viruses expanding into mammalian hosts.
Synthesized historical milestones, epidemiological surveillance data, and structural insights regarding highly pathogenic avian influenza evolution from 1878 to 2024.
Evaluated molecular mechanisms facilitating cross-species adaptation, including the hemagglutinin polybasic cleavage site and the '1+7' ribonucleoprotein core complex.
Analyzed the 2024 detection of clade 2.3.4.4b H5N1 in U.S. dairy cattle, focusing on clinical features, viral shedding dynamics, and public health ramifications.
Demonstrates expanding mammalian tropism in HPAI H5N1, highlighted by the first documented instance of viral shedding directly into dairy cattle milk.
Identifies specific molecular characteristics, such as the polybasic cleavage site and ribonucleoprotein architecture, as central drivers of elevated replication efficiency and cross-species infection.
Identifies milk-borne viral shedding as an unprecedented non-avian transmission route, underscoring significant agricultural risks and the necessity of integrated One Health surveillance.