title: Sequence variation in ROP8 gene among Toxoplasma gondii isolates from different hosts and geographical localities.
abstract: The protozoan parasite Toxoplasma gondii has a worldwide distribution; it can cause serious diseases in humans and almost all other warm-blooded animals. Different genotypes of T. gondii result in different lesions in the same host. T. gondii rhoptry protein 8 (TgROP8) is a major factor of T. gondii acute virulence. We examined sequence variation in the TgROP8 gene among T. gondii isolates from different hosts and geographical localities. The TgROP8 gene was amplified from individual isolates and sequenced. A phylogenetic tree was constructed using Bayesian inference, maximum parsimony, and maximum likelihood based on the sequences obtained plus TgME49 from the ToxoDB database. The TgROP8 gene was 1728 bp in length for all the examined T. gondii strains, and their A+T contents were 45.37-45.95%. Sequence analysis detected 140 (0.06-5.56%) variable nucleotide positions resulting in 96 (0-10.78%) amino acid substitutions. Sequence variations in the TgROP8 gene resulted in polymorphic restriction sites for endonucleases BstBI, BsaI, and XhoI, which allowed the differentiation of the three classical genotype strains (types I, II, and III) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). However, phylogenetic analyses indicated that the TgROP8 gene is not a suitable genetic marker for population studies of T. gondii.
authors.affiliation: College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province, China.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.affiliation: 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, Gansu Province, China.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.affiliation: 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, Gansu Province, China.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.affiliation: College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province, China.
authors.forename: C R
authors.initials: CR
authors.lastname: Wang
authors.affiliation: College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing, Heilongjiang Province, China.
authors.forename: X Q
authors.initials: XQ
authors.lastname: Zhu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001499:Bayes Theorem; D004587:Electrophoresis, Agar Gel; D014644:Genetic Variation; D005843:Geography; D006790:Host-Parasite Interactions / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D014122:Toxoplasma / Q000235:genetics* / Q000302:isolation & purification*
chemical_list: D015800:Protozoan Proteins; C109324:ROP8 protein, Toxoplasma gondii