Senecavirus A: An Emerging Vesicular Infection in Brazilian Pig Herds

Vesicular diseases are clinically and economically important infections that affect farm animals. North American studies have suggested that Senecavirus A infection might be associated with a vesicular disease in pigs known as porcine idiopathic vesicular disease (PIVD). In the beginning of 2015, outbreaks of porcine vesicular disease have occurred in six Brazilian states from three geographical regions. Official diagnostic tests were performed with negative results for classical vesicular diseases of compulsory reporting. This study investigated Senecavirus A infection in PIVD outbreaks in which other aetiological agents were ruled out. A primer set was designed to amplify a 542-bp product size of VP3/VP1 region of Senecavirus A genome in RT-PCR assay. Primer specificity was analysed in silico and in porcine biological specimens. For this, clinical specimens were collected from eight pig herds affected with PIVD, including vesicular fluid (n = 4) and swabs (n = 7) and scrapings of ruptured vesicles and ulcerative lesions (n = 5) from weaned and adult pigs. Clinically healthy animals (n = 52) of PIVD-affected and non-affected pig herds also were evaluated for Senecavirus A infection. The 16 samples from PIVD-affected animals were positive for Senecavirus A in the RT-PCR assay, while none of the clinically healthy pigs were detected with the virus. Sequencing analysis revealed high nucleotide (87.6-98.5%) and amino acid (95-99.4%) similarities to SVV-01 prototype and other Senecavirus A strains from North American pigs. Primer set presented herein was suitable for molecular characterization of Senecavirus A. The results suggest that Senecavirus A was the aetiological agent of the vesicular disease outbreaks in the evaluated pig herds. This is the first study to report the Senecavirus A infection in clinically affected pigs outside of North America. Senecavirus A was considered a novel emerging pathogen associated with an important vesicular disease in Brazil.