Novel reassortant A/H5N1 avian influenza in Cambodia
A new study published in medRxiv share insights on the emergence of a novel reassortant clade 2.3.2.1c Avian Influenza A/H5N1 virus, which has been associated with human cases in Cambodia.
After nearly a decade without reported human A/H5N1 infections, Cambodia experienced a resurgence with 16 cases between February 2023 and August 2024, all linked to the clade 2.3.2.1c virus, including a novel reassortant strain. Notably, 14 of these cases involved a novel reassortant A/H5N1 virus that combines gene segments from both clade 2.3.2.1c and clade 2.3.4.4b viruses.
The study details the genomic epidemiology of these infections, indicating that the reassortant virus has replaced the previously dominant 2.3.2.1c genotype in poultry in Cambodia since October 2023. Molecular marker analysis suggests that the novel reassortant genotype may have increased potential for mammalian adaptation, with specific mutations (e.g., E627K in the PB2 gene segment) indicating enhanced capacity for mammalian infection. The study emphasizes the critical role of rapid genomic surveillance and coordinated efforts between human and animal health sectors in managing zoonotic threats and understanding the dynamics of virus spillover events.
