Guangxi Key Laboratory of Brain and Cognitive Neuroscience, College of Basic Medicine, Guilin Medical University, Guilin, 541199, People's Republic of China.
Acta Parasitol. 2024 Mar;69(1):227-232. doi: 10.1007/s11686-023-00740-8. Epub 2023 Nov 18.
In the past for more than 100 years at least 300 genotypes of Toxoplasma gondii were recorded and several traditional isolates such as RH, GT1, ME49, PRU and VEG were used repeatedly to clarify the pathogenic mechanisms and the epidemiological significance to human, but for if their virulence was mutative post-iterative passages it remains confused.
Therefore, in the study, seven genetically distinct T. gondii including C7 and PYS previously discovered in China were reidentified by sequencing the head of hsp40 locus to distinguish their virulence in vitro post-rejuvenation in vivo.
Our data showed the nucleotides were different in 18 positions and 7 of them can be used to type T. gondii isolates. Total 634 plaques of T. gondii without two or more overlaps indicated that RH and GT1 tachyzoites possess stronger power than other five isolates in vitro (p < 0.001), followed by ME49, PRU, C7, PYS, and the weakest VEG. Based on the shapes of plaques, we found the ratio of their width/length was associated with the virulence of T. gondii, and speculated it could be used to judge T. gondii tachyzoites in vitro, whereas the data of simple linear regression analyses did not agree.
Together, virulence of seven genetically distinct T. gondii isolates that can be distinguished by seven mutative nucleotides in hsp40 was redefined in vitro post-rejuvenation in vivo, and it cannot be directly judged just according to the shapes of plaques formed in vitro.
在过去的 100 多年中，至少记录了 300 种刚地弓形虫基因型，并且反复使用了几种传统分离株，如 RH、GT1、ME49、PRU 和 VEG，以阐明其对人类的致病机制和流行病学意义，但对于它们在反复传代后的毒力是否发生了变异，仍然存在混淆。
因此，在这项研究中，通过测序 hsp40 基因座的头部，重新鉴定了在中国先前发现的 7 种遗传上不同的刚地弓形虫（包括 C7 和 PYS），以区分它们在体内再生活跃后的体外毒力。
我们的数据显示，18 个位置的核苷酸存在差异，其中 7 个位置可用于对刚地弓形虫分离株进行分型。总共 634 个无两个或更多重叠的刚地弓形虫噬斑表明，RH 和 GT1 速殖子在体外的活力强于其他 5 种分离株（p<0.001），其次是 ME49、PRU、C7、PYS 和最弱的 VEG。根据噬斑的形状，我们发现它们的宽/长比与刚地弓形虫的毒力有关，推测它可以用于判断体外的刚地弓形虫速殖子，但简单线性回归分析的数据并不一致。
综上所述，通过 hsp40 中 7 个突变核苷酸可区分的 7 种遗传上不同的刚地弓形虫分离株的体外毒力在体内再生活跃后被重新定义，并且不能仅仅根据体外形成的噬斑的形状来直接判断。
