Molecular cloning of a cDNA encoding the porcine type XVII collagen noncollagenous 16 A domain and localization of the domain to the upper part of porcine skin basement membrane zone

Bullous pemphigoid is an autoimmune blistering human skin disease mediated by immunoglobulin (Ig)G autoantibodies targeting skin basement membrane component type XVII collagen, a transmembrane protein. Also designated BP180 and BPAG2, type XVII collagen is an extracellular matrix element essential for the connection between the epidermis and the underlying dermis. In addition to being a target antigen in the human disease bullous pemphigoid, type XVII collagen is also targeted by autoantibodies of canine, feline, equine and porcine patients suffering from a similar blistering skin disease. Previously, enzyme-linked imunosorbent assay and Western blot analyses have shown that autoantibodies from pigs affected with bullous pemphigoid recognize the human NC16A domain of type XVII collagen. To facilitate the development of porcine model of bullous pemphigoid, we isolated cDNA encoding the porcine type XVII collagen NC16A domain using a reverse transcription-polymerase chain reaction technique. The amino acids deduced from the NC16A cDNA showed 61% identity with the sequence of human NC16A. An antibody generated against a 20-amino acid peptide within the porcine NC16A localized the NC16A epitope to the upper part of porcine skin basement membrane zone. Our data provide further information of the porcine bullous pemphigoid target antigen and may help investigators for their further studies of this disease.