Research progress in attenuated vaccines against Toxoplasma gondii
ZHANG Hai-sheng, MA Yuan-yuan, XIE Shi-chen, LIANG Qin-li, ZHU Xing-quan, WANG Jin-lei
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China
Abstract：Toxoplasma gondii is an obligate intracellular parasite that can infect almost all warm-blooded animals, including humans. Approximately one-third of the world’s population is infected with T. gondii. Immuno-competent hosts often show no obvious symptoms after infection with T. gondii, but for immunocompromised people, such as patients with AIDS or pregnant women, it can cause severe clinical symptoms or even death. With the continual improvements in the quality of human life, the harmful effects of T. gondii on human health, the animal industry and public health are increasing. At present, no specific drug is available for treating toxoplasmosis, and vaccination is the most effective way to control toxoplasmosis. However, traditional T. gondii vaccines evoke poor immunity. The attenuated vaccines obtained through natural screening can potentially revert to virulence and therefore are not suitable for immunodeficient animals or people. Traditional gene editing technology has low efficiency, and the construction of gene knockout strains is complicated. The application of CRISPR-Cas9 gene editing technology in T. gondii has provided a new direction for the development of anti-T. gondii vaccines. Many attenuated vaccine strains have successfully been constructed and have shown good immune protection; these strains are thus the most promising candidates for anti-Toxoplasma vaccines. This article summarizes the research progress and development prospects for attenuated vaccines against T. gondii, and provides a reference for follow-up studies on anti-T. gondii vaccines.
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