★ A BAFF gene has been cloned from grass carp. ★ The structure of grass carp BAFF is very similar to the BAFFs from other species. ★ The grass carp BAFF is predominantly expressed in the skin and spleen. ★ The grass carp BAFF is significantly up-regulated against bacterial and viral infections.
The TNF superfamily B cell activating factor (BAFF) is a central cytokine in several diseases. A BAFF gene has been cloned from grass carp (Ctenopharyngodon idella), analyzed its structure, and investigated its expression pattern in various tissues after Aeromonas hydrophila and Aquareovirus infection. The open reading frame of grass carp BAFF (gcBAFF) consists of 804 bases encoding 267 amino acids. Phylogenetic analysis shows the gcBAFF is most closely related to other teleost BAFFs with the highest similarity to zebrafish. RT-PCR analysis shows the gcBAFF transcript is expressed in a wide range of tissues with the highest expression in skin and spleen. Upon induction by A. hydrophila and Aquareovirus, its expression is significantly up-regulated in gill, liver, kidney, spleen and skin as compared to PBS injected fish. The association of increased BAFF expression after bacterial and viral infections suggests that it plays a potentially important role in immune system of fish.