Defining the genetic relationship of protegrin-related sequences and the in vivo expression of protegrins

Protegrins (PGs) are potent antimicrobial peptides that act on a broad spectrum of microorganisms, including bacteria, fungi and some enveloped viruses. We analyzed the expression pattern of protegrins in 17 different pig tissues using RT-PCR, and developed an anti-(PG-1) polyclonal IgG. Western blot analysis using the antibody showed that protegrins are mainly present as prepropeptide forms in normal tissues, rather than as mature peptides. Immunohistochemical analysis showed that protegrin expression was specific to a few cell types, including neutrophils, pulmonary club, epithelial and Leydig cells. Genetic analyses of the five previously reported protegrin sequences showed that they are encoded at a single locus, rather than from multiple paralogous genes. By genotyping 28 animals across five breeds, we identified eight different alleles of the PGs.