Schistosoma mansoni: Infectivity and immunizing effects of in vitro derived schistosomula attenuated by X irradiation

Irradiated and nonirradiated in vitro derived schistosomula of Schistosoma mansoni were injected intraperitoneally into mice. Sixteen percent of nonirradiated schistosomula, 8% of those irradiated with 1000 R, and virtually none of those irradiated with 3000 R and above survived in mice for 5 weeks. However, those irradiated with 3000 R survived in small numbers for shorter periods of time. Schistosomula irradiated with 3000 or 6000 R were used to immunize mice against subsequent infection with cercariae. Prior ip injections of schistosomula irradiated with 3000 R resulted in reductions in worm burden after challenge from 5 to 91%; the observed protection was related to the number of inoculations. The subcutaneous route appeared to be less effective. Schistosomula irradiated with 6000 R produced less protection than those irradiated with 3000 R.     

Schistosoma mansoni: Complement and antibody damage,mediated by human eosinophils and neutrophils,in killing schistosomula in vitro

The time and course of damage to Schistosoma mansoni schistosomula mediated by human eosinophils and neutrophils and by antibody (A) and/or complement (C) was studied. The rate of schistosomula death was significantly higher in the complement containing systems (i.e., “A + C” or “C alone”) when compared to A alone. In general, at all the time points studied, the percentage of killing in the three systems was A + C > C alone > A alone irrespective of whether the effector cells were neutrophils or eosinophils. Preferential killing of schistosomula by eosinophils, as compared to neutrophils, was observed with C alone and A + C, but only when eosinophils and neutrophils from the same donor were compared. In contrast, eosinophils and neutrophils appeared to be equally effective in killing antibody-coated schistosomula.A comparison was made of the susceptibility to killing of schistosomula prepared mechanically or by skin penetration. There was no appreciable difference in terms of susceptibility to killing by the various combinations of eosinophils, neutrophils, antibody, and complement between these two forms of schistosomula.The preferential killing of complement-coated, as compared to antibody-coated schistosomula by eosinophils appears to be relatively rapid, an observation which may be of significance both in natural and acquired immunity to migrating larval helminths.     

Schistosoma mansoni: identification, characterization, and purification of the spine glycoprotein by monoclonal antibody

A tegumental surface membrane antigen of Schistosoma mansoni has been identified by use of a monoclonal antibody. The binding of ¹²⁵I-labeled monoclonal antibody showed that proteins sharing antigenic determinants recognized by this monoclonal antibody were present in cercariae and worms of both sexes, but were absent from schistosome egg extract. The protein molecules expressing these antigenic determinants differed in molecular weight: 120,000 in cercaria and 170,000 in male and female worms. The cercarial glycoprotein immunoprecipitated with the monoclonal antibody was also immunoprecipited by sera of infected humans, as shown by two-dimensional gel electrophoresis and tryptic peptide mapping. The location of the glycoprotein identified by the monoclonal antibody was restricted to the spines of the schistosomular surface, the tubercle-associated spines of the male worm, and the dorsal spines of the female worm. The spine glycoprotein was readily purified by immunoaffinity chromatography. These findings are discussed in relation to parasite development and the relevance of this antibody for serodiagnosis and immunoprophylaxis.