Senecavirus A (SVA) in finishing swine: diagnosis and viral isolation

Abstract

ABSTRACT: Senecavirus A (SVA) has been a problem in Brazil since the end of 2014. The infections caused by SVA have disrupted the productive chain in Brazil, as it can be confused with foot-and-mouth disease. Although, the virus has remained endemic in the country, an increase in the number of cases of the disease was observed in 2018. The aim of the present study was to conduct the differential diagnosis of foot-and-mouth disease in an outbreak of vesicular disease in finishing swine. Animals (160-170 days old) were kept on a farm with 6000 pigs in Minas Gerais State, Brazil. The morbidity and mortality rates were 20% and 2.2%, respectively. The diagnosis was performed by RT-PCR, using primers that determine the amplification of an internal region of the 3D gene. Furthermore, samples were inoculated into BHK-21 cell culture for viral isolation. In the first passage under cultivation, a cytopathogenic effect compatible with SVA replication (rounding and detachment of the cell monolayer) was observed. The viral identity was confirmed using two additional assays: indirect immunofluorescence assay (IFA) and nucleotide sequencing. Both tests confirmed that the infection was caused by SVA. In summary, we described a method for the diagnosis and viral isolation of SVA, a virus that arrived in Brazil in 2014 and has become endemic in the country.