Basic Research
Copyright ©2006 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Apr 21, 2006; 12(15): 2363-2368
Published online Apr 21, 2006. doi: 10.3748/wjg.v12.i15.2363
Biological role of surface Toxoplasma gondii antigen in development of vaccine
Ke-Yi Liu, Dian-Bo Zhang, Qing-Kuan Wei, Jin Li, Gui-Ping Li, Jin-Zhi Yu
Ke-Yi Liu, Dian-Bo Zhang, Qing-Kuan Wei, Jin Li, Gui-Ping Li, Shandong Institute of Parasitic Diseases, Jining 272033, Shandong Province, China
Jin-Zhi Yu, Department of Population Medicine and Diagnostic Sciences, Veterinary Medical College, Cornell University, Ithaca, NY 14853, United States
Supported by China Ministry of Human Affairs and Department of Science and Technology of Shandong Province, No. 031050115
Correspondence to: Professor Keyi Liu, PhD, Shandong Institute of Parasitic Diseases, Jining Taibai Zhong Road #11, Jining 272033, Shandong Province, China.
Telephone: +86-537-2601023 Fax: +86-537-2353277
Received: July 15, 2005
Revised: July 20, 2005
Accepted: October 9, 2005
Published online: April 21, 2006

AIM: To analyze the biological role of the surface antigen of Toxoplasma gondii (T gondii) in development of vaccine.

METHODS: The surface antigen of T gondii (SAG1) was expressed in vitro. The immune response of the host to the antigen was investigated by detection of specific antibody reaction to SAG1 and production of cytokines. Mice were immunized with recombinant SAG1 and challenged with lethal strain of T gondii RH. The monoclonal antibody to r-SAG1 was prepared and used to study the effects of SAG1 on T gondii tachyzoites under electromicroscope.

RESULTS: The mice immunized with recombinant SAG1 delayed death for 60 h compared to the control group. The recombinant SAG1 induced specific high titer of IgG and IgM antibodies as well as IFN-γ, IL-2 and IL-4 cytokines in mice. In contrast, IL-12, IL-6 and TNF-α were undetectable. When T gondii tachyzoites were treated with the monoclonal antibody to r-SAG1, the parasites were gathered together, destroyed, deformed, swollen, and holes and gaps formed on the surface.

CONCLUSION: SAG1 may be an excellent vaccine candidate against T gondii. The immune protection induced by SAG1 against T gondii may be regulated by both hormone- and cell-mediated immune response.

Keywords: Toxoplasma gondii, Recombinant SAG1, Monoclonal antibody, Cytokines, Morphology change