Protective immunity induced by Toxoplasma gondii rhoptry protein 16 (ROP16) against toxoplasmosis in mice

Clin Vaccine Immunol. 2010 Nov 24. [Epub ahead of print]

Protective immunity induced by Toxoplasma gondii rhoptry protein 16 (ROP16) against toxoplasmosis in mice

Yuan ZG, Zhang XX, He XH, Petersen E, Zhou DH, He Y, Lin RQ, Li XZ, Chen XL, Shi XR, Zhong XL, Zhang B, Zhu XQ.

State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, CAAS, Lanzhou, Gansu Province 730046, PR China; Department of Parasitology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province 510642, PR China; College of Agriculture, South China Agricultural University, 483 Wushan Street, Tianhe District, Guangzhou, Guangdong Province 510642, PR China; Department of Infectious Diseases, Clinical Institute, and Institute of Medical Microbiology and Immunology, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark; College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan Province 650201, PR China.

Abstract
Toxoplasma gondii can infect a large variety of domestic and wild animals and human beings, sometimes causing severe pathology. Rhoptries are involved in T. gondii invasion and host cell interaction, and have been implicated as important virulence factors. In this study, we constructed a DNA vaccine expressing rhoptry protein 16 (ROP16) of T. gondii, and evaluated the immune responses it induced in Kunming mice. The gene sequence encoding ROP16 was inserted into the eukaryotic expression vector pVAX I. 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 mice immunized with pVAX-ROP16 developed a high level of specific antibody responses against T. gondii ROP16 expressed in Escherichia coli, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production, compared with other mice immunized with either empty plasmid or phosphate-buffered saline, respectively. The results showed that pVAX-ROP16 induces significant humoral and cellular Th1 immune responses. After lethal challenge, the mice immunized with the pVAX-ROP16 showed a significantly (P values < 0.05) prolonged survival time (21.6 ± 9.9 days) compared with control mice which died within 7 days of challenge. Our data demonstrate, for the first time, that ROP16 triggered a strong humoral and cellular response against T. gondii, and that ROP16 is a promising vaccine candidate against toxoplasmosis, worth further development.

PMID: 21106780 [PubMed - as supplied by publisher]