swineorigin

Swineorigin is a term used to describe influenza A viruses that derive part of their ancestry from swine, with particular prominence given to the virus that caused the 2009 H1N1 pandemic. During that outbreak, public health authorities described the emergent virus as a swine-origin influenza A(H1N1), highlighting its swine-related gene heritage.

Genetically, the A(H1N1)pdm09 virus was a reassortant containing gene segments from multiple lineages, including North American swine and Eurasian swine lineages, with contributions from avian and human influenza lineages as well. The influenza A genome comprises eight RNA segments, and reassortment among these segments in pig hosts can generate novel viruses capable of efficiently infecting humans. The 2009 virus appeared in humans in North America and rapidly spread worldwide, leading the World Health Organization to declare a pandemic. In subsequent years, the virus was designated A(H1N1)pdm09 and has since become a seasonal influenza A lineage that continues to circulate and evolve.

Naming and public understanding of swineorigin have evolved. The term drew attention to the swine connection, but it has also been criticized as potentially misleading since the virus now circulates in humans and often reassorts with other lineages in both humans and swine. Today, many sources refer to the virus by its official designation, while recognizing its complex ancestry that includes swine, avian, and human influenza gene segments.