MIC6 is a potential vaccine candidate against toxoplasmosis in mice

Vaccine. 2009 Aug 28. [Epub ahead of print]

Toxoplasma gondii microneme protein 6 (MIC6) is a potential vaccine candidate against toxoplasmosis in mice

Peng GH, Yuan ZG, Zhou DH, He XH, Liu MM, Yan C, Yin CC, He Y, Lin RQ, Zhu XQ.

Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, People's Republic of China.

Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. Microneme proteins which are responsible for adhesion and invasion have been implicated as vaccine candidates. In this study, we constructed a DNA vaccine expressing microneme protein 6 (MIC6) of T. gondii, and evaluated the immune response it induced in Kunming mice. The gene sequence encoding MIC6 was inserted into the eukaryotic expression vector pVAXI. We immunized Kunming mice intramuscularly. After immunization, we evaluated the immune response using lymphoproliferative assay, cytokine and antibody measurements, and the survival times of mice challenged lethally. The results showed that the group immunized with pVAX-MIC6 developed a high level of specific antibody responses against T. gondii lysate antigen (TLA), a strong lymphoproliferative response, and significant levels of IFN-gamma, IL-2, IL-4 and IL-10 production, compared with the other groups immunized with empty plasmid or phosphate-buffered saline, respectively. These results demonstrate that pVAX-MIC6 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-MIC6 showed an increased survival time (13.3+/-1.2 days) compared with control mice died within 7 days of challenge. Our data demonstrate, for the first time, that MIC6 triggered a strong humoral and cellular response against T. gondii, and that the antigen is a potential vaccine candidate against toxoplasmosis, worth further development.

PMID: 19720368 [PubMed - as supplied by publisher]