State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Center for Emerging and Zoonotic Diseases, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
Mol Biol Evol. 2022 Jul 2;39(7). doi: 10.1093/molbev/msac150.
Genetic recombination plays a critical role in the emergence of pathogens with phenotypes such as drug resistance, virulence, and host adaptation. Here, we tested the hypothesis that recombination between sympatric ancestral populations leads to the emergence of divergent variants of the zoonotic parasite Cryptosporidium parvum with modified host ranges. Comparative genomic analyses of 101 isolates have identified seven subpopulations isolated by distance. They appear to be descendants of two ancestral populations, IIa in northwestern Europe and IId from southwestern Asia. Sympatric recombination in areas with both ancestral subtypes and subsequent selective sweeps have led to the emergence of new subpopulations with mosaic genomes and modified host preference. Subtelomeric genes could be involved in the adaptive selection of subpopulations, while copy number variations of genes encoding invasion-associated proteins are potentially associated with modified host ranges. These observations reveal ancestral origins of zoonotic C. parvum and suggest that pathogen import through modern animal farming might promote the emergence of divergent subpopulations of C. parvum with modified host preference.
遗传重组在具有耐药性、毒力和宿主适应性等表型的病原体的出现中起着关键作用。在这里，我们检验了这样一个假设，即在同域祖先种群之间发生重组会导致具有不同宿主范围的动物源寄生虫微小隐孢子虫的变异体的出现。对 101 个分离株的比较基因组分析已经确定了七个通过距离隔离的亚种群。它们似乎是两个祖先种群的后代，西北欧的 IIa 和来自西南亚的 IId。在同时存在两个祖先亚型和随后的选择清除的同域重组导致了具有镶嵌基因组和改变宿主偏好的新亚种群的出现。端粒附近的基因可能参与了亚种群的适应性选择，而编码入侵相关蛋白的基因的拷贝数变异可能与改变的宿主范围有关。这些观察结果揭示了动物源微小隐孢子虫的祖先起源，并表明通过现代动物养殖引入病原体可能会促进具有改变宿主偏好的微小隐孢子虫变异亚种群的出现。
