ABSTRACT
Background@#Enteritis is one of the most frequently reported symptoms in piglets infected with porcine circovirus type 2 (PCV2), but the immunopathogenesis has not been reported. @*Objectives@#This study examined the effect of a PCV2 infection on the intestinal mucosal immune function through morphological observations and immune-related molecular detection. @*Methods@#Morphological changes within the ileum of piglets during a PCV2 infection were observed. The expression of the related-molecules was analyzed using a gene chip. The immunocyte subsets were analyzed by flow cytometry. The secretory immunoglobulin A (SIgA) content was analyzed by enzyme-linked immunosorbent assay. @*Results@#The PCV2 infection caused ileal villus damage, intestinal epithelial cells exfoliation, and an increase in lymphocytes in the lamina propria at 21 days post-infection.Differentially expressed genes occurred in the defense response, inflammatory response, and the complement and coagulation cascade reactions. Most of them were downregulated significantly at the induction site and upregulated at the effector site. The genes associated with SIgA production were downregulated significantly at the induction site. In contrast, the expression of the Toll-like receptor-related genes was upregulated significantly at the effector site. The frequencies of dendritic cells, B cells, and CD8 + T cells were upregulated at the 2 sites. The SIgA content decreased significantly in the ileal mucosa. @*Conclusions@#PCV2 infections can cause damage to the ileum that is associated with changes in immune-related gene expression, immune-related cell subsets, and SIgA production.These findings elucidated the molecular changes in the ileum after a PCV2 infection from the perspective of intestinal mucosal immunity, which provides insights into a further study for PCV2-induced enteritis.
ABSTRACT
In order to survey the prevalence of encephalomyocarditis virus (EMCV) infection in pigs in Hebei Province from 2006 to 2008,a total of 1306 swine serum from 31 farms in 10 regions in Hebei were tested for antibodies against EMCV nonstructural protein 2C by ELISA.Positive rates of antibodies in different regions and different age groups were analyzed.The results showed that antibodies against EMCV 2C were found in 176 out of 1306 serum samples collected from Hebei Province and the total positive rate was 13.48%.Seroprevalence of EMCV infection appeared in six out of ten surveyed regions and the highest positive rate was 26%.There was significant difference of seroprevalence in EMCV infection between breeder sows and other swine species.This survey indicated that EMCV infection has occurred in pig farms in most regions of Hebei Province and EMCV-carried breeder sows were one of the crucial causes for EMCV infection and prevalence.