role of Cryptosporidium parvum-derived phospholipase in intestinal epithelial cell invasion

In the Cryptosporidium parvum-infected intestinal epithelial cell, the parasite occupies an unusual extracytoplasmic location at the luminal surface, but how the invading zoites interact with the host cell to achieve this niche is poorly understood. This study examined the role of secretory phospholipase A₂ (sPLA₂), a known virulence factor for several pathogenic microorganisms, in establishing C. parvum intracellularly. Initially, it was established that there was sPLA₂ activity in homogenates of C. parvum oocysts. C. parvum reproduction in two human enterocyte cell lines was significantly reduced by a specific PLA inhibitor, p-bromophenacylbromide, and by sheep anti-sPLA₂ antibodies developed against PLA₂ of bee (Apis mellifera) venom. Treatment of either C. parvum sporozoites or enterocytes with sPLA₂ derived from cobra (Naja naja) venom before initiation of infection increased the numbers of intracellular parasites. Thus, C. parvum PLA₂ may play an important part in establishing the parasite within the enterocyte.