Porcine hemagglutinating encephalomyelitis coronavirus in Argentina. A serological survey on farms of high, medium and low biosecurity

ALARCON L; MORTOLA EC; LARSEN A; SERENA MS; MONTERRUBBIANESI M; VIDAL P.; QUIROGA MA; LOZADA MI; PERFUMO CJ; GIMÉNEZ-LIROLA L.; PIÑEYRO, P

Chongqing

Congreso; 25th International Pig Veterinary Society Congress (IPVS 2018) and 2018 International PRRS Symposium; 2018

Porcine hemagglutinating encephalomyelitis coronavirus virus (PHEV) is a neurotropic virus that affects pigs ≤ 3 week of age. The clinical disease is characterized by neurologic and/or digestive disorders associated with high mortality, reaching 100% mortality in naive farms. The infection has been reported in all of the major pig-raising countries inEurope, Asia, and North America, where the infection appears to be endemic and virus circulation seems to undergo subclinical. Thus far, only Argentina and China have reported clinical outbreaks. Serological tests available for PHEV included: IFAT, HI, VN, ELISA and lateral flow immunochromatographic assay. The aim of this study was to evaluate the seroprevalence of PHEV on farms of high (HB), medium (MB) and low biosecurity (LB) in Argentina without clinical sings suggestive of PHEV infection. Seventeen farms were selected and clustered by their biosecurity status as follow: 7 with HB, 5 with MB, and 5 with LB. A total of 961 samples from 14 breeding herds and 3 farrow-to-finish farms were evaluated. Blood samples were collected from 30 randomly selected gilts, sows or growing/fattener pigs. The association between the biosecurity categories, farm size, positive sows/gilt/fatteners in the herd and within-herd prevalence was analyzed by Chi-square test and One-way analysis of the mean (ANOVA). The presence of PHEV specific antibodies was evaluated by an indirect ELISA based on the amino terminal portion of the PHEV spike protein (S1). The overall seroprevalence was 41.62 % (CI: ± 3.12). The percentage of positive farms was 100%, 80% and 60% for HB, MB and LB farms, respectively. The percentage of positive sows was 45.71% (CI: ±4.41), gilts 43.57 % (CI: ±8.21) and grower/fattener pigs 34.74% (CI: ±5.13). Amongst positive farms, the within herd prevalence varied from 12.5% to 86.6% for sows, 25% to 85.7% for gilts and 3.7% to 90% for grower/fattener pigs. No statistical differences were observed on seroprevalence by age category or biosecurity status. The presence of antibodies in grower/finisher suggested that colostral antibodies may persist for more than 6 weeks or animals were subclinically infected during the grower-finisher stage. This survey demonstrates that PHEV is widespread and undergoes subclinical in Argentina farms.