Sequence Variation inToxoplasma gondii rop17Gene among Strains from Different Hosts and Geographical Locations

Abstract

Genetic diversity of T. gondii is a concern of many studies, due to the biological and epidemiological diversity of this parasite. The present study examined sequence variation in rhoptry protein 17 (ROP17) gene among T. gondii isolates from different hosts and geographical regions. The rop17 gene was amplified and sequenced from 10 T. gondii strains, and phylogenetic relationship among these T. gondii strains was reconstructed using maximum parsimony (MP), neighbor-joining (NJ), and maximum likelihood (ML) analyses. The partial rop17 gene sequences were 1375 bp in length and A+T contents varied from 49.45% to 50.11% among all examined T. gondii strains. Sequence analysis identified 33 variable nucleotide positions (2.1%), 16 of which were identified as transitions. Phylogeny reconstruction based on rop17 gene data revealed two major clusters which could readily distinguish Type I and Type II strains. Analyses of sequence variations in nucleotides and amino acids among these strains revealed high ratio of nonsynonymous to synonymous polymorphisms (>1), indicating that rop17 shows signs of positive selection. This study demonstrated the existence of slightly high sequence variability in the rop17 gene sequences among T. gondii strains from different hosts and geographical regions, suggesting that rop17 gene may represent a new genetic marker for population genetic studies of T. gondii isolates.

Sequence variation in the Toxoplasma gondii ROP20 gene among strains from different hosts and geographical locations

“…Of these variable positions, 18 were transitions (A↔G and C↔T) and 11 were transversions (A↔C, A↔T, G↔C, and G↔T) in the coding region of the ROP20 gene (R = transition/transversion = 1.6). These results were similar to those found in previous studies for Hsp60 and ROP17 (Lu et al, 2014;Zhang et al, 2014).…”

Sequence Variation in Superoxide Dismutase Gene of <i>Toxoplasma gondii</i> among Various Isolates from Different Hosts and Geographical Regions

“…Based on the partial sequences of the SOD locus, phylogenetic analysis revealed 2 major clusters with only a little difference of bootstrap values, and it cannot differentiate T. gondii strains to their genotypes, implying a low genetic diversity. Our results were similar to some studies such as MIC13, eIF4A [ 25 , 26 ] and different from other genetic markers including GRA5, GRA6, and ROP17 [ 21 - 23 ]. The low sequence variation (0-1.0%) in the partial SOD gene suggests that SOD gene could not be an ideal genetic marker for differentiation of the T. gondii strains or intraspecific phylogenetic analyses.…”

“…GRA5, GRA6, and ROP17) have shown signs of positive selection, and could be sufficient for genotyping of T. gondii isolates. [ 21 - 23 ].…”

Rhoptry protein 47 gene sequence: A potential novel genetic marker for population genetic studies of Toxoplasma gondii

“…The restriction fragments were resolved in 3% agarose gel, stained by the GoldenView™, and photographed by a gel documentation system (UVP GelDoc-It TM Imaging System, Cambridge, UK). (Chen et al, 2012;Zhang et al, 2014;Fazaeli et al, 2000). Our results indicated that ROP47 gene sequences are conserved within a genotype, but are highly divergent among different T. gondii genotypes.…”

“…Phylogenetic reconstruction was based on the ROP47 gene sequences determined in the present study plus the corresponding sequences of strains VEG and ME49 available in ToxoDB (http://toxodb.org/toxo/) using three methodologies, namely maximum parsimony (MP), maximum likelihood (ML) and neighbor-joining (NJ), with the sequence of Neospora caninum (NCLIV_025740) as the outgroup. These methodologies analysis were performed using PAUP* 4.0b10 (Swofford, 2002), following previous studies Chen et al, 2012a;Zhang et al, 2014). Phylograms were drawn by the Tree View program version1.65.…”