The role of porcine reproductive and respiratory syndrome virus as a risk factor in the outbreak of porcine epidemic diarrhea in immunized swine herds

The aim of the study was to investigate the relation between porcine epidemic diarrhea (PED) and porcine reproductive and respiratory syndrome virus (PRRSV). Here, we constructed a dynamic clinical experimental model in which sows were infected with PRRSV. The stability of the experimental model was surveyed by detecting the levels of antibodies against classical swine fever virus (CSFV) or PRRSV, respectively. In both group A (infected group) and group B (healthy group), the CSFV antibody level was not significantly different (P > 0.05). In group B, the PRRSV antibody level was also not significantly different (P > 0.05) at the three times of testing. The incidence of porcine epidemic diarrhea virus (PEDV) in piglets and PEDV-carrying rate of sows was detected by real-time fluorescent RT-PCR. In group A, PEDV infection of piglets and the PEDV-carrying rate of sows were significantly higher than in group B (P < 0.01) and the PEDV strains were within the same group according to the phylogenetic analysis based on the complete S gene. The results suggested that PRRSV was a risk factor in the outbreak of PED in immunized swine herds. Besides that, the experimental model was stable and no interference factors affected the results of the study.