Molecular cloning, in vitro expression and bioactivity of goose B-cell activating factor.

B-cell activating factor (BAFF), belonging to the TNF family, is critical for B cell survival and maturation. cDNA of goose BAFF (gBAFF) was amplified from goose spleen by RT-PCR. The open reading frame (ORF) of gBAFF encodes a protein of 288-amino acid. The gBAFF shows 98, 92, 44 and 55% amino acid sequence identity with duck (dBAFF), chicken (cBAFF), mouse (mBAFF) and human BAFF (hBAFF), respectively. RT-PCR results showed that gBAFF mRNA is expressed in thymus and more highly expressed in the bursa of Fabricius and spleen. Recombinant soluble gBAFF (gsBAFF) expressed in Escherichia coli has molecular weight of approximately 19kDa. In vitro, purified gsBAFF was able to promote bursa B cells survival/proliferation in goose, duck and chicken. Furthermore, recombinant dsBAFF and csBAFF have a positive effect on goose, duck and chicken bursa B cells survival/proliferation. These findings indicate that gBAFF plays an important role in the survival/proliferation of goose B cells and, owing to its high evolutionary conservation, functional cross-reactivity exists between chicken, duck and goose BAFF.