Immunity to Onchocerca lienalis microfilariae in mice

The model of Onchocerca lienalis microfilariae (mff) injected into CBA and T.O. strains of mice has been used to examine immunity to skin-dwelling microfilariae following exposure to a range of species oF nelmmms Mice which had received a primary infection with O. cervicalis mff were significantly resistant to challenge with O. lienalis mfT(58% reduction relative to challenge controls). Immunization with the uterine contents (eggs and mff) of O. lienalis, O. gutturosa or O. volvulus conferred equivalent levels of protection agains challenge with O. lienalis mff (66 to 75%). Similar results were obtained with immunizations in mice that employed either fresh or freeze-killed eggs of O. gutturosa . Significant reductions in the recoveries of O. lienalis mff were also demonstrated following the intraperitoneal implantation of adult male worms of O. gutturosa (30 to 52%), the adults of either sex of Dipetalonema viteae (60%), or after infection witn Trichinella spiralis (27 to 81%). Infections with the trematode, Schistosoma mansoni , had a negligible effect on mff recoveries. It is concluded that partial resistance in mice to Onchocerca mff may be stimulated by factors, yet to be determined, that are neither stage nor species-specific.