Bioinformatic and expression analysis of novel porcine beta-defensins

Beta-defensins are a major group of mammalian antimicrobial peptides. Although more than 30 beta-defensins have been identified in humans, only one porcine beta-defensin has been reported. In this article we report the identification and initial characterization of 11 novel porcine beta-defensins (pBD). Using bioinformatic approaches, we screened 287,821 porcine expressed sequence tags for similarity of their predicted peptides to known human beta-defensins and identified full-length or partial sequences for the 11 novel pBDs. Similar to the previously identified pBD1, all of these peptides have a consensus beta-defensin motif. A differential expression pattern for these newly identified genes was found. For example, unlike most beta-defensins, pBD2 and pBD3 were expressed in bone marrow and in other lymphoid tissues including thymus, spleen, lymph nodes, duodenum, and liver. Including pBD2 and pBD3, six porcine beta-defensins were expressed in lung and skin. Several newly identified porcine beta-defensins, including pBD123, pBD125, and pBD129, were expressed in male reproductive tissues, including lobuli testis and some segments of the epididymis. Phylogenetic analysis indicates that in most cases the evolutionary relationship between individual porcine beta-defensins and their human orthologs is closer than the relationship among beta-defensins in the same species. These findings establish the existence of multiple porcine beta-defensins and suggest that the pig may be an ideal model for the characterization of beta-defensin diversity and function.