Senecavirus A: An Emerging Vesicular Infection in Brazilian Pig Herds

Abstract

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.

Detection of the Emerging Picornavirus Senecavirus A in Pigs, Mice, and Houseflies

“…Notably, the number of cases of SVA has jumped from 2 in 2014 to over 100 in 2015 (December 2015 report of the Swine Health Monitoring Project). Since November 2014, SVA has also been frequently reported in swine in Brazil (7,9). However, the factors that contributed to the reemergence of SVA in the United States and its emergence in Brazil remain unknown.…”

“…In the past 10 years, sporadic reports have described the association of SVA with cases of swine idiopathic vesicular disease (SIVD) in Canada and in the United States (3)(4)(5)(6). Notably, since November 2014, several reports of SVA associated with vesicular disease in swine have been described in Brazil, and since March 2015, an increased number of cases of SVA associated with vesicular lesions and neonatal mortality in swine have been reported in the United States (7)(8)(9)(10)(11).…”

“…Characteristic lesions associated with SVA infection in pigs include vesicles on the snout, oral mucosa, hoofs, and coronary bands, and typical clinical signs include lameness, lethargy, and anorexia (4)(5)(6)(7)9). Recently, SVA has also been associated with increased mortality (30% to 70%) in piglets that are Ͻ7 days of age (7).…”

Serological and Molecular Detection of Senecavirus A Associated with an Outbreak of Swine Idiopathic Vesicular Disease and Neonatal Mortality

“…Vesicular lesions in pigs resemble those in other foreign vesicular diseases, such as foot-and-mouth disease (FMD), vesicular stomatitis (VS), swine vesicular disease (SVD), and vesicular exanthema of swine (VES). In addition, numerous reports associate the presence of SVA with increased neonatal mortality in piglets that are Յ7 days of age (10,11). Although SVA has been described in the U.S. swine population since the late 1980s (14), due to the rapid increase in incidence and geographic range (15), SVA can be considered an emerging infectious disease.…”

“…It was not until 2007 that the presence of SVA was linked with IVD outbreaks in Canada (9). Most recently, SVA was detected in sporadic and transient outbreaks of IVD in the United States, Brazil, and China (10)(11)(12)(13). Lesions observed in cases of IVD associated with SVA infection are characterized by vesicle formations and epidermal erosions that progress to ulcers of the coronary band, oral cavity, and nasal planum.…”