TY - JOUR AU - Nelson, Martha AU - Schaefer, Rejane AU - Gava, Danielle AU - Cantão, Maurício Egídio AU - Ciacci-Zanella, Janice Reis T1 - Influenza A Viruses of Human Origin in Swine, Brazil T2 - Emerging Infectious Disease journal PY - 2015 VL - 21 IS - 8 SP - 1339 SN - 1080-6059 AB - The evolutionary origins of the influenza A(H1N1)pdm09 virus that caused the first outbreak of the 2009 pandemic in Mexico remain unclear, highlighting the lack of swine surveillance in Latin American countries. Although Brazil has one of the largest swine populations in the world, influenza was not thought to be endemic in Brazil’s swine until the major outbreaks of influenza A(H1N1)pdm09 in 2009. Through phylogenetic analysis of whole-genome sequences of influenza viruses of the H1N1, H1N2, and H3N2 subtypes collected in swine in Brazil during 2009–2012, we identified multiple previously uncharacterized influenza viruses of human seasonal H1N2 and H3N2 virus origin that have circulated undetected in swine for more than a decade. Viral diversity has further increased in Brazil through reassortment between co-circulating viruses, including A(H1N1)pdm09. The circulation of multiple divergent hemagglutinin lineages challenges the design of effective cross-protective vaccines and highlights the need for additional surveillance. KW - viruses KW - influenza A virus KW - swine KW - pigs KW - Brazil KW - evolution KW - interspecies transmission KW - reassortment KW - humans KW - influenza KW - zoonoses DO - 10.3201/eid2108.141891 UR - https://wwwnc.cdc.gov/eid/article/21/8/14-1891_article ER - End of Reference