Equine β-defensin-1: full-length cDNA sequence and tissue expression

β-Defensins are cysteine-rich endogenously produced antimicrobial peptides that play an important role in innate immune defense. Although, previous investigations have identified β-defensins in several mammalian species, no reports have identified equine β-defensins. Using a strategy of database searching for expressed sequence tags (EST) we identified putative expression of equine β-defensins in hepatic tissue. Based on this information, sequence specific primers were designed for the equine gene enabling the identification of the full-length cDNA sequence of equine β-defensin-1. Comparative analyses showed that equine β-defensin-1 has 46–52% amino-acid identity with other β-defensins, sharing the greatest identity with porcine β-defensin-1. Complete conservation of cysteine residues was maintained between the species evaluated, and RT-PCR analysis revealed diverse mRNA tissue expression for equine β-defensin-1. These data extend the repertoire of equine antimicrobial peptides and expand our understanding of equine innate immunity.