Vaccine efficacy of recombinant cathepsin D aspartic protease from Schistosoma japonicum

Abstract

Mice were vaccinated with recombinant Schistosoma japonicum cathepsin D aspartic protease, expressed in both insect cells and bacteria, in order to evaluate the vaccine efficacy of the schistosome protease. Mean total worm burdens were significantly reduced in vaccinated mice by 21-38%, and significant reductions in female worm burdens were also recorded (22-40%). Vaccination did not reduce fecundity; rather, we recorded increased egg output per female worm in vaccinated animals, suggesting a crowding effect. Vaccinated mice developed high levels of antibodies (predominantly IgG1, IgG2a and IgG2b isotypes), but there was no correlation between antibody levels and protective efficacy. Immune sera from vaccinated mice did not inhibit the in vitro degradation of human haemoglobin by the recombinant protease, and passive transfer of serum or antibodies from vaccinated animals, before and after parasite challenge, did not significantly reduce worm or egg burdens in recipient animals. These results suggest that antibodies may not play a key role in the protective effect elicited, and that protection may be due to a combination of humoral and cell-mediated responses

A Recombinant Aspartyl Protease ofCoccidioides posadasiiInduces Protection against Pulmonary Coccidioidomycosis in Mice

“…The authors proposed that the protective response was antibody mediated. An aspartyl protease isolated from Schistosoma japonicum, causative agent of schistosomiasis, has also been evaluated as a vaccine in a murine model of this disease (44). Immunization with the recombinant protein resulted in reduced worm burden in challenged mice but little to no effect in reducing the fecundity of the pathogen.…”

Construction and expression of aspartic protease from Onchocerca volvulus* as ompA fusion protein in a mutant strain of Salmonella typhimurium

“…Vaccine efficacy of recombinant cathepsin D aspartic protease from Schistosoma japonicum (Verity et al, 2001) and Haemonchus contortus (Longbottom et al, 1997) has been reported. Immunolocalisation experiments performed by the authors (Jolodar et al, unpublished data) indicated that the recombinant OV7A protein encoding an aspartic protease was predominantly associated with the hypodermis and inner membrane zone of the uterine wall of adult females.…”

Lipid core peptide targeting the cathepsin D hemoglobinase ofSchistosoma mansonias a component of a schistosomiasis vaccine

“…[10][11][12] Vaccination with recombinant forms of S. japonicum CatD in the mouse model of schistosomiasis achieved significant reductions in total worm burden across numerous trials. 13 RNA interference targeting the gene encoding S. mansoni CatD resulted in a lethal phenotype (growth retardation) and the reduction in the ability of the parasite to effectively digest Hb in vitro. 14 While it is possible to generate recombinant Sm-CatD for small-scale vaccine testing, high-yield expression of eukaryotic proteases is problematic.…”