Background: Bursa of Fabricius is the acknowledged central humoral immune organ.
The bursal-derived peptides play the important roles on the immature B cell development and antibody
Objectives: Here we explored the functions of the new isolated bursal hexapeptide and pentapeptide
on the humoral, cellular immune response and antigen presentation to avian influenza virus ( AIV)
vaccine in mice immunization.
Method: The bursa extract samples were purified following RP HPLC method, and were analyzed
with MS/MS to identify the amino acid sequences. Mice were twice subcutaneously injected with
AIV inactivated vaccine plus with two new isolated bursal peptides at three dosages, respectively.
On two weeks after the second immunization, sera samples were collected from the immunized
mice to measure AIV-specific IgG antibody levels and HI antibody titers. Also, on 7th day after the
second immunization, lymphocytes were isolated from the immunized mice to detect T cell subtype
and lymphocyte viabilities, and the expressions of co-stimulatory molecule on dendritic cells in the
Results: Two new bursal hexapeptide and pentapeptide with amino acid sequences KGNRVY and
MPPTH were isolated, respectively. Our investigation proved the strong regulatory roles of bursal
hexapeptide on AIV-specific IgG levels and HI antibody titers, and lymphocyte viabilities, and the
significant increased T cells subpopulation and expressions of MHCII molecule on dendritic cells
in the immunized mice. Moreover, our findings verified the significantly enhanced AIV-specific
IgG antibody and HI titers, and the strong increased T cell subpopulation and expressions of CD40
molecule on dendritic cells in the mice immunized with AIV vaccine and bursal pentapeptide.
Conclusion: We isolated and identified two new hexapeptide and pentapeptide from bursa, and
proved that these two bursal peptides effectively induced the AIV-specific antibody, T cell and
antigen presentation immune responses, which provided an experimental basis for the further clinical
application of the bursal derived active peptide on the vaccine improvement.