Limited sequence variation in rhoptry protein 41 gene among Toxoplasma gondii isolates from different hosts and geographical locations

ABSTRACT

Toxoplasma gondii is a medically and agriculturally important protozoan parasite that can infect virtually all the mammalian and avian species. Previous studies showed that the family of rhoptry proteins (ROPs) plays a key role in the invasion process of T. gondii, and its several members can be potential marker for population genetic researches of Toxoplasma. In order to estimate whether other member is also suitable as the novel genetic marker, the variation of ROP41 gene among 11 T. gondii isolates from different hosts and geographical locations and two reference strains was examined in this study. Our results showed that all the examined sequence of TgROP41 gene was 1473 bp in length, and their A+T contents were between 48.47% and 48.88%. Sequence analysis presented 14 nucleotide mutation positions (0%-0.54%), leading to 5 amino acid substitutions (0%-0.61%) through alignment with T. gondii ME49 strain (ToxoDB: TGME49_266100). Furthermore, phylogenetic analyses by MP and BI methods based on deduced amino acid sequences of TgROP41 gene was only able to distinguish the type I strain, but not able to separate the two classical genotypes (Type II and III) into the respective clusters. These results indicated limited sequence diversity in the TgROP41 gene.