Characterization of Influenza A subtypes in growing and finishing pigs in integration of the Southern Region of Brazil.
viruses; RT qPCR; subtyping; diagnosis; respiratory diseases.
The Influenza A virus (IAV) is an RNA virus that causes respiratory diseases and has zoonotic character, and is considered endemic in commercial swine herds in Brazil. Facing several antigenic variations and genetically distinct lineages (subtypes H1N1, H1N2, H3N2) in the country, fast and accurate diagnostic tools are necessary to know the subtypes present in each farm, in order to monitor and control the disease more assertively. This study aims to use RT- qPCR for detection of Influenza A virus and multiplex subtyping through the identification of mutations in the genes of surface glycoproteins: Hemagglutinin and Neuraminidase. A total of 1988 samples from pigs in two productive phases, nursery and finishing, were analyzed in the Animal Health laboratory. Collected from four different integration units of an agro-industry in the states of Santa Catarina and Rio Grande do Sul, through nasal swabs and lungs from clinical cases, between April and December 2021. The presence of IAV was detected in 16.65% of the samples. The sample type with the highest positivity was lungs (84.21%), compared to nasal swabs (16%). 99 of the positive samples were eligible for subtype RT-qPCR, of these, 57.57% had at least one surface glycoprotein identified (HA or NA), of which 2 subtypes were detected: H1panN1pan (3.51%) and one sample of the H1huN1pan subtype. This study was able to identify the presence of IAV using RT-qPCR and detect at least one surface glycoprotein from the positive samples. However, it is necessary to conduct a further study through genome sequencing to evaluate the phylogeny of the most genetically distinct strains and those that it was not possible to identify subtypes.