Differential expression of TgMIC1 in isolates of Chinese 1 Toxoplasma with different virulence

Background: The predominant genotype of Toxoplasma in China is the Chinese 1 (ToxoDB#9) lineage. TgCtwh3 and TgCtwh6 are two representative strains of Chinese 1, exhibiting high and low virulence to mice, respectively. Little is known regarding the virulence mechanism of this non-classical genotype. Our previous RNA sequencing data revealed differential mRNA levels of TgMIC1 in TgCtwh3 and TgCtwh6. We aim to further confirm the differential expression of TgMIC1 and its significance in this atypical genotype. Methods: Quantitative real-time PCR was used to verify the RNA sequencing data; then, polyclonal antibodies against TgMIC1 were prepared and identified. Moreover, the invasion and proliferation of the parasite in HFF cells were observed after treatment with TgMIC1 polyclonal antibody or not. Results: The data showed that the protein level of TgMIC1 was significantly higher in high-virulence strain TgCtwh3 than in low-virulence strain TgCtwh6 and that the invasion and proliferation of TgCtwh3 were inhibited by TgMIC1 polyclonal antibody. Conclusion: Differential expression of TgMIC1 in TgCtwh3 and TgCtwh6 may explain, at least partly, the virulence mechanism of this atypical genotype.

Automated summary

The study revealed significant differences in the protein level of TgMIC1 between the high-virulence strain TgCtwh3 and low-virulence strain TgCtwh6, with the TgMIC1 polyclonal antibody inhibiting the invasion and proliferation of TgCtwh3. These findings suggest that the differential expression of TgMIC1 may partly explain the virulence mechanism in this atypical genotype.