The changes of immune-related molecules within the ileal mucosa of piglets infected with porcine circovirus type 2

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.

Surface Display of porcine circovirus type 2 antigen protein cap on the spores of bacillus subtilis 168: An effective mucosal vaccine candidate

“…Infection with PCV2 caused necrosis of ileal mucosal cells and inhibition of mucosal coagulation in piglets. In addition, it altered the expression of immune-related genes such as CCL4, CCL5 and CCL28, induced accelerated apoptosis of intestinal mucosal lymphocytes, altered immune cell subsets and inhibited production of ileal sIgA ( 37 ). Damage to the intestinal mucosa - the first defense barrier of the animal’s intestine - in turn leads to more pathogens that can easily pass through the intestinal mucosa to attack the animal.…”

“…Damage to the intestinal mucosa - the first defense barrier of the animal’s intestine - in turn leads to more pathogens that can easily pass through the intestinal mucosa to attack the animal. However, current inactivated vaccines and Cap protein-based subunit vaccines cannot induce effective mucosal immunity after intramuscular injection ( 37 , 38 ). The coat protein of spores is considered an ideal platform for antigen delivery because of its excellent mucosal immune adjuvant properties and strong resistance to harsh physical and chemical environments.…”

Porcine Lawsonia intracellularis Ileitis in Italy and Its Association with Porcine Circovirus Type 2 (PCV2) Infection

“…The emergence of PCV2 and its associated diseases in the first decade of the 21st century has dramatically changed disease patterns in pig farming, highlighting the pathogenic potential of endemic agents as a direct consequence of the immunosuppressive abilities of PCV2 [ 19 ]. PCV2 infection is known to impair both innate and adaptive immune responses [ 20 ], leading to alterations in intestinal mucosal immunity, such as changes in the expression of immune-related genes, local cellular immune set-up, and IgA production [ 21 ]. When a disease is caused by more than just a single pathogen, it is necessary to determine the primary and secondary roles of each.…”

Oral DNA vaccine adjuvanted with cyclic peptide nanotubes induced a virus-specific antibody response in ducklings against goose parvovirus

“… 2020 ) and porcine circovirus (PCV2) (Shi et al. 2020 ). In the oral-, nasal-cavity, or digestive tract, the amounts of virus primary attachment and infection could be largely inhibited by the mucous IgA antibodies.…”