Identification and characterization of Toxoplasma gondii aspartic protease 1 as a novel vaccine candidate against toxoplasmosis

Abstract

BackgroundToxoplasma gondii is an obligate intracellular parasite that can pose a serious threat to human health by causing toxoplasmosis. There are no drugs that target the chronic cyst stage of this infection; therefore, development of an effective vaccine would be an important advance. Aspartic proteases play essential roles in the T. gondii lifecycle. The parasite has four aspartic protease encoding genes, which are called toxomepsin 1, 2, 3 and 5 (TgASP1, 2, 3 and 5, respectively).MethodsBioinformatics approaches have enabled us to identify several promising linear-B cell epitopes and potential Th-cell epitopes on TgASP1, thus supporting its potential as a DNA vaccine against toxoplasmosis. We expressed TgASP1 in Escherichia coli and used the purified protein to immunize BALB/c mice. The antibodies obtained were used to determine where TgASP1 was localized in the parasite. We also made a TgASP1 DNA vaccine construct and evaluated it for the level of protection conferred to mice against infection with the virulent RH strain of T. gondii.ResultsTgASP1 appears to be a membrane protein located primarily at the tip of the T. gondii tachyzoite. Investigation of its potential as a DNA vaccine showed that it elicited strong humoral and cellular immune responses in mice, and that these responses were mediated by Th-1 cells. Mice immunized with the vaccine had greater levels of protection against mortality following challenge with T. gondii RH tachyzoites than did those immunized with PBS or the empty vector control.ConclusionsTgASP1 is a novel candidate DNA vaccine that merits further investigation.

The effect of chitosan nanospheres on the immunogenicity of Toxoplasma lysate vaccine in mice

“…This is in agreement with Zaharoff et al (2007) who used b-galactosidase vaccine in either chitosan solution or FIA and reported no significant difference between them. A significant increase in IFN c level was also obtained by Meng et al (2012), Chuang et al (2013), Zhao et al (2013a) and Cong et al (2013).…”

New tools for NTD vaccines: A case study of quality control assays for product development of the human hookworm vaccineNa-APR-1M74

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Bioinformatic characterization of aspartic protease (AP) enzyme in seed plants

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