Sixty specific-pathogen-free chickens were randomly divided into 2 groups (30 chickens for each group) to determine the effect of swine gut antimicrobial peptides (SGAMP) on intestinal mucosal immunity. All chickens were raised in negative-pressure isolators and fed the same diet. The results were as follows. (1) In the SGAMP group, the number of mast cells was increased markedly in the duodenum from d 21 to 49 (P < 0.05), and similar results were observed in the jejunum and ileum after being treated with SGAMP (P < 0.05). However, fewer mast cells were observed in those same tissues in the control. (2) Intraepithelial lymphocytes in the duodenum, jejunum, and ileum were increased significantly from d 21 to 49 in the SGAMP group compared with the control (P < 0.05). (3) Compared with the control, goblet cells were increased significantly in duodenum and jejunum from d 35 to 49 (P < 0.05) after SGAMP treatment and in the ileum were increased from d 21 to 49 (P < 0.05). (4) Swine gut antimicrobial peptides upgrade the expression of secretory IgA at different sites within the intestinal tract. The results strongly support that SGAMP can enhance the intestinal mucosal immune parameters of specific-pathogen-free chickens. Our research contributes to the further understanding of immunoregulatory mechanisms of intestinal mucosal immunity and the contribution of SGAMP to this process.

Infectious bronchitis virus (IBV), the causative agent of infectious bronchitis, results in respiratory disease, nephritis, and poor egg production and quality in chicken. Antimicrobial peptides possess potent antimicrobial activities and are regarded as promising therapeutic alternatives in the fight against microorganisms. To assess the in vitro antiviral activity of swine intestine antimicrobial peptides (SIAMP) against IBV, 45 chick embryos were randomly assigned into 3 groups, 15 for each group. Embryos in group 1 were inoculated with IBV. Group 2 was inoculated with SIAMP-IBV intermixture. Group 3 was used as a control and inoculated with sterile PBS. Allantoic fluid was collected for hemagglutination titer assay. In addition, weight gain, mortality, and pathological changes for each group were recorded. The results showed that no distinct pathological changes were found in chick embryos after they were inoculated with SIAMP-IBV intermixture and the mortality was reduced remarkably compared with the IBV-infected group. Weight gain of embryos in the SIAMP-IBV intermixture group was significantly higher than the IBV-infected embryos (P < 0.01), which was also higher than the control group (P < 0.05). Furthermore, the hemagglutination titer in the SIAMP-IBV group was significantly lower than that in the IBV-infected group (P < 0.01). These results indicated that SIAMP can inhibit virus replication and reduce tissue injury caused by IBV.