Effects of Gal-13 on the Content of Immunoglobulin, Proliferation of Lymphocyte and Antibody Titers after Vaccination with Infectious Bursal Disease Virus Vaccine in Chickens

Gal-13 is an antimicrobial peptide isolated from chicken intestine. Ninety chickens were randomly divided into two groups (45 chickens for each group) to determine the effect of oral administration of Gal-13 on the acquired immune response. The chickens in the first group were fed a diet without Gal-13 as the control, and the chickens in the second group were fed the same diet, except that Gal-13 ($1{\mu}g/ml$) was suspended in drinking water just after hatching. Samples of blood, thymus, bursa of fabricius and spleen were taken at day 1, 4, 7, 10 and 17. The chickens in both groups received infectious bursal disease virus vaccine at day 20, and then sera samples were collected for analysis at 14, 21, 28 and 35 days after vaccination. The results showed: (1) Gal-13 could enhance the content of immunoglobulin (Ig)G at the age of 4 to10 days (p<0.05) and IgM at the age of 4 and 10 days (p<0.05) in the serum; (2) In vitro experiments showed that Gal-13 (0.625-1.250${\mu}g/ml$) enhanced the proliferation of peripheral blood lymphocytes of the chickens stimulated by lipopolysaccharide (LPS) and concanavlin A (ConA). Compared to the control, Gal-13 (1 ${\mu}g/ml$) enhanced the proliferation of bursa lymphocytes at 17 days of age (p<0.01) and thymus lymphocytes at 7 days of age (p<0.01), but restrained lymphocyte proliferation in chicken spleen and differed significantly at day 10 (p<0.01); (3) Gal-13 enhanced infectious bursal disease virus antibody in sera of chickens 21 days after infectious bursal disease virus vaccine administration (p<0.05). These results suggested that Gal-13 could modulate adaptive immune responses of chickens.