there is a classic trifecta of avian; swine; and human host, along with the re-assortment of genetic segments that occurs during repeated passaging between spec

there is a classic trifecta of avian; swine; and human host, along with the re-assortment of genetic segments that occurs during repeated passaging between species until human trophic characters are attained. Genetic Reassortment of Avian, Swine, and Human Influenza A Viruses in American Pigs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC112910/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC112910/ [1999] [J Virol. 1999 Oct; 73(10): 8851–8856] https://doi.org/10.1128%2Fjvi.73.10.8851-8856.1999 https://doi.org/10.1128%2Fjvi.73.10.8851-8856.1999