Background: Bursa of Fabricius plays the vital functions on B cell development and
antibody production in poultry. The bursal-derived peptide plays the essential roles on avian
immature B cell development.
Objectives: Here we explored the functions of the recently reported bursal nonapeptide (BP9) on
the antibody production and the molecular basis of BP9 on avian immature B cell.
Methods: Chicken were twice immunized with Avian Influenza Virus (AIV) inactivated vaccine
plus with BP9 at three dosages, respectively. On two weeks after the second immunization, sera
samples were collected from all experimental groups to measure AIV-specific Agglutination
Inhibition (HI) antibody titers. Also, on 7th day after the second immunization, spleen lymphocytes
were isolated from the immunized chicken to detect the lymphocyte viabilities. DT40 cells were
treated with BP9 from 0.02 to 2 μg/mL for 4 and 20h to detect sIgM mRNA levels, and total RNAs
from BP9-treated DT40 cells were collected to investigate the gene expression profiles of DT40
cells, and to analyze the enriched pathways and functional biological processes. Finally, nine gene
expressions were validated with quantitative PCR (qPCR).
Results: Our investigation proved the strong regulatory roles of BP9 on AIV-specific HI antibody
titers and lymphocyte viabilities. BP9 promoted sIgM mRNA levels in DT40 cells, and upregulated
598 gene expressions and downregulated 395 gene expressions in DT40 cells with 0.2μg/mL BP9
treatment. Moreover, our findings verified the significantly enriched six pathways and various the
biological functional processes of BP9 on avian immature B cell. Also, we found eight signaling
pathways in the enriched biological processes of BP9-treated DT40 cells, and the expressions of
nine selected genes with qPCR were identical to that of microarray data.
Conclusion: BP9 promoted the antibody production in the 21-old-day chicken immunization, and
stimulated the sIgM expression in DT40 cells. Furthermore, we analyzed the gene expression
profile and immune-related biological processes of DT40 cells treated with BP9, which provided
some new insights into the mechanism on immature B cell development, and provided important
references for adjuvant development on vaccine improvement and clinical application.