title: MOLECULAR CHARACTERIZATION AND SEQUENCE PHYLOGENETIC ANALYSIS OF SURFACE ANTIGEN 3 (SAG3) GENE OF LOCAL INDIAN ISOLATES (CHENNAI AND IZATNAGAR) OF Toxoplasma gondii.
abstract: OBJECTIVE
  The molecular characterization of local isolates of Toxoplasma gondii is considered significant so as to assess the homologous variations between the different loci of various strains of parasites.
  
  
  METHODS
  The present communication deals with the molecular cloning and sequence analysis of the 1158 bp entire open reading frame (ORF) of surface antigen 3 (SAG3) of two Indian T. gondii isolates (Chennai and Izatnagar) being maintained as cryostock at the IVRI.
  
  
  METHODS
  The surface antigen 3 (SAG3) of two local Indian isolates were cloned and sequenced before being compared with the available published sequences.
  
  
  RESULTS
  The sequence comparison analysis revealed 99.9% homology with the standard published RH strain sequence of T. gondii. The strains were also compared with other established published sequences and found to be most related to the P-Br strain and CEP strain (both 99.3%), and least with PRU strain (98.4%). However, the two Indian isolates had 100% homology between them.
  
  
  CONCLUSIONS
  Finally, it was concluded that the Indian isolates were closer to the RH strain than to the P-Br strain (Brazilian strain), the CEP strain and the PRU strains (USA), with respect to nucleotide homology. The two Indian isolates used in the present study are known to vary between themselves, as far as homologies related to other genes are concerned, but they were found to be 100% homologous as far as SAG3 locus is concerned. This could be attributed to the fact that this SAG3 might be a conserved locus and thereby, further detailed studies are thereby warranted to exploit the use of this particular molecule in diagnostics and immunoprophylactics. The findings are important from the point of view of molecular phylogeny.
authors.affiliation: Department of Parasitology, College of Veterinary Sciences & Animal Husbandry, U. P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go Anusandhan Sansthan, Mathura, India.
authors.forename: Vikrant
authors.initials: V
authors.lastname: Sudan
authors.affiliation: Division of Parasitology, IVRI, Izatnagar, India.
authors.forename: Anup Kumar
authors.initials: AK
authors.lastname: Tewari
authors.affiliation: Department of Parasitology, GADVASU, Ludhiana, India.
authors.forename: Harkirat
authors.initials: H
authors.lastname: Singh
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics*; D005838:Genotype; D007194:India; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014122:Toxoplasma / Q000145:classification / Q000235:genetics*
chemical_list: D016054:DNA, Protozoan; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; C087692:SAG3 protein, Toxoplasma gondii