Influenza A virus circulation in pig nurseries in the state of Santa Catarina, Brazil

Abstract The objective of this work was to evaluate the infection caused by influenza A virus (IAV) subtypes and its incidence in pig nurseries in the state of Santa Catarina, Brazil. A total of 423 nursery pigs were sampled in 11 farms, and IAV circulation, viral RNA, and antibodies were identified. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) was used to detect viral RNA in nasal swab samples (70.2%) and to subtype 33 viruses, of which 18 (54.5%) from six nurseries were the H3N2 virus, 6 (18.1%) from two nurseries were H1N1pdm, and 9 (27.2%) from three nurseries could not be subtyped. The enzyme-linked immunosorbent assay (ELISA) detected the presence of IAV antibodies (68%), which was confirmed by the hemagglutination inhibition test, revealing a higher prevalence of antibodies for the H3N2 virus (38.0%), followed by H1N1pdm (23.8%) and H1N2 (3.23%). The obtained data showed that 10.3% of the swine reacted to at least two viral antigens. There is a high prevalence of influenza A virus infection in all 11 piglets nurseries sampled by viral RNA and antibody detection. H3N2 and H1N1pdm, in this order, are the most detected viral subtypes in the 11 sampled nurseries.