Vaccination of rats against the rodent hookworm Nippostrongylus brasiliensis with a recombinant superoxide dismutase fails to protect against infection

Abstract

AbstractAnti-oxidant enzymes including superoxide dismutase (SOD) protect cells from damage by oxygen radicals produced during respiration. There is also a substantial body of evidence that anti-oxidant enzymes facilitate the survival of parasitic helminths, including gastrointestinal nematodes, within the host. Superoxide dismutase has been shown to be released by a variety of parasitic helminths and may protect them from host mediated oxidative immune responses. As it may play a parasite protective role during infections SOD has been investigated as a vaccine candidate in a range of helminth parasites including Schistosoma mansoni, Acanthocheilonema viteae and Haemonchus contortus. Here, we sought to evaluate the protective potential of SOD against the rat hookworm Nippostrongylus brasiliensis, a commonly utilised laboratory infection, as a vaccination model. A cytosolic SOD from this parasite, with high sequence homology to a putative extracellular form of the enzyme was cloned and then expressed in bacteria. The resultant recombinant protein was assessed for enzyme activity and used to immunise rats prior to a single challenge infection with the parasite. No protection was observed and monitoring systemic and mucosal antibody responses and mast cell protease levels in superoxide dismutase vaccinated rats suggested that this recombinant SOD was only weakly immunogenic.