MOLECULAR CHARACTERIZATION AND SEQUENCE PHYLOGENETIC ANALYSIS OF SURFACE ANTIGEN 3 (SAG3) GENE OF LOCAL INDIAN ISOLATES (CHENNAI AND IZATNAGAR) OF Toxoplasma gondii

Abstract

Context and 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.Design and setting: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.Method: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.Conclusion: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.

Genotypes of T. Gondii in Patients With Haematological Malignancies at a State Cancer Institute in South India

“…In the Indian subcontinent, locus specific genotyping of animal isolates yielded varied results-while SAG2 locus typing resulted in types II and III. 24 SAG3 locus sequencing of cryostocks of strains revealed genotype I 25 and sequencing of GRA6 locus showed genotype III. 26 However, since genotyping of the parasite in all these studies were based on single locus analysis, a more accurate picture of the prevailing genotype in the animals can only be obtained by a wider analysis on multiple loci.…”

Isolation and characterization of Toxoplasma gondii from small ruminants (sheep and goats) in Chennai City, South India

“…Our study is in agreement with the previously reported studies. Some of the studies showed the genotypes of T. gondii circulating among backyard chicken species in India had revealed two type II and 5 type III genotypes based on SAG2 genotyping (Sreekumar et al 2003), type I based on SAG3 (Sudan et al 2015) and type III based on GRA6 (Biradar et al 2014); Further, a recent study in the HIV (human immune deficiency virus) infected human patients, who succumbed to severe cerebral toxoplasmosis revealed recombinant genotypes of type II/III and type I/III (Vijaykumar et al 2016). Further detailed studies are needed to accurately assess the genotypes circulating among small ruminants.…”

“…Limited studies from the African continent (Velmurugan et al 2008;Al-Kappany et al 2010), the Middle East and the Arabic peninsula, revealed mostly of type II and III (Salant et al 2009;Dubey et al 2010). In the Asian continent, various studies specially in China from animals (Yan et al 2014;Tian et al 2014;Li et al 2015) and humans (Wang et al 2013(Wang et al , 2015 revealed the predominance of Chinese I (ToxoDB#9) genotype with the limited numbers of archetypal lineages I, II and III (Tian et al 2014;Wang et al 2013Wang et al , 2015Zhou et al 2009); in India, limited genotyping revealed types II and III (Sreekumar et al 2003;Biradar et al 2014), type I (Sudan et al 2015). On the contrary, isolates from South America are highly diverse (Dubey et al 2002(Dubey et al , 2007Lehmann et al 2006;Rajendran et al 2012;Shwab et al 2014) and grouped them into different classification (Pena et al 2008).…”

Immunological And Genotyping Study of Toxoplasma Gondi and Its Relationship with Toll Like Receptor 4 “TLR4” Polymorphism in Aborted Women

“…To determine the genotype of Toxoplasma in the 30 women infected with toxoplasmosis, the sag3 primer was used in DNA sequencing analysis (Table 2). The methodology was carried out as stated by Sudan et al (6) The DNA from the placenta of the 30 women infected with toxoplasmosis was extracted using Add Prep Genomic DNA extraction kit"(Addpio®, South Korea), according to the information provided by the manufacturer. Sag3 primers were used in DNA sequencing analysis.…”