The article discusses the mechanism by which highly pathogenic variants of the H5N1 avian influenza virus are created through a process called "polymerase capture"[5][6]. Research published in the journal Science in March 2026 examines how viral polymerase – the enzyme responsible for replicating genetic material – can be captured and changed during the evolution of the virus[5][6]. This mechanism represents a key process in the emergence of highly pathogenic variants that have an increased ability to replicate and transmit[5][6]. At the same time, other research suggests that the H5N1 virus acquires adaptive mutations in the polymerase that allow it to replicate better in mammalian cells, including humans[1]. These mutations, such as PB2 M631L and PA K497R, occur in the sequences of the bovine virus and improve its infectivity[1]. Identification and monitoring of these emerging adaptive mutations is important for assessing the pandemic potential of avian influenza[3].