Classico-molecular targeting of oligopeptidase B, cysteine protease and variable surface glycoprotein (VSG) genes of Trypanosoma evansi

Silent Trypanosoma evansi infection in humans from India revealed by serological and molecular surveys, and characterized by variable surface glycoprotein gene sequences

BACKGROUND

The importance of emerging atypical human trypanosomosis is gaining momentum due to increasing detection and its possible impact on human health. A cross sectional study of atypical human trypanosomosis due to Trypanosoma evansi was carried out in Kolkata and Canning area of West Bengal state of India where previously a death was reported.

METHODS

In this study blood and serum samples from 173 individuals were collected during August to December 2014. To check the presence of antibodies against T. evansi, card agglutination test and for the presence of T. evansi specific DNA, PCR were conducted.

RESULTS

T. evansi infection was identified in 5.2% (9/173) human blood samples by CATT serological test (Card agglutination test for trypanosomosis). PCR targeting VSG gene sequences suggested active T. evansi infection in 2.89% (5/173). VSG gene sequences herein determined for five isolates from human cases shared high similarity (89.4-100%). Phylogenetic inference clustered the human isolates with other isolates from different host species from India and other countries, forming a clade exclusive of Indian isolates (84.0 to 100% sequence similarity).

CONCLUSION

First report of symptomless human T. evansi infection detected by combined serological and PCR assays. First phylogenetic analysis of VSG gene sequences including human isolates of T. evansi in which Indian isolates of T. evansi from human and other hosts clustered in a single clade.

Associative Genetic Diversity of RoTat 1.2 VSG in Different Trypanosoma evansi Isolates

BACKGROUND

Numerous phylogenetic markers have been tested over a period of time for delineating evolutionary history of haemoflagellate-Trypanosoma evansi.

PURPOSE

To find out the associative genetic diversity, within the various isolates of T. evansi across the globe, based on RoTat 1.2 VSG gene.

METHODS

A total of 5 equine isolates of T. evansi from Northern India were characterized. PCR products were sequenced and sequences were compared with available sequences across India and world. Phylogenetic tree was constructed based on maximum parsimony (MP) method with the tree-bisection-regrafting (TBR) algorithm.

RESULTS

Indian isolates formed multiple clades with two haplotypes. The present isolates showed 99.49-100.00% nucleotide homology within themselves. On broader line, Indian isolates were found to be closer to Egyptian isolates than the African counterparts. Few of the Indian isolates showed marked resemblance with a particular Egyptian isolate than with their Indian counter parts. Another remarkable finding is the close association of equine isolates from India with other equine isolates and their clear divergence from isolates of T. evansi affecting other hosts from India and abroad.

CONCLUSION

Vast genetic divergence was seen between the isolates suggesting of multiple distinct lineages of T. evansi amongst the Indian livestock. Interestingly, variations in sequences were seen based on the host range of isolates. The findings are very important from molecular evolutionary point of view.

Phylogenetic studies on RoTat 1.2 VSG of Trypanosoma evansi isolate from semi arid India

RoTat 1.2 variant surface glycoprotein (VSG) is considered to be one of the most important VSGs expressed in many of the isolates of Trypanosoma evansi. This accounts for its utility as a potent molecule for both molecular and serological based detection of Surra. Of late, there are reports of its absence and variation from a fewer isolates of T. evansi. The study of these variations by means of molecular phylogenetic studies is of immense significance in determining the evolutionary phylogeny of these T. evansi isolates. With this information in the background, the present study was designed to clone and characterize RoTat 1.2 VSG from horse isolate of T. evansi from semi arid regions of India. There after, the gene was compared with various other isolates across the world. Interestingly, theisolate was found to be closer to camel isolates from Egypt than the other known isolates from India and Kenya. The finding is important from evolutionary point of view.

First report of molecular characterization and phylogenetic analysis of RoTat 1.2 VSG of Trypanosoma evansi from equine isolate

Rotat 1.2 variant surface glycoprotein (VSG) is considered to be an important VSG expressed in most of the isolates of Trypanosoma evansi. This makes the molecule an important candidate for both molecular- and serological-based detection of surra. There are ample reports of existence of this gene in isolates from cattle, buffalo, and camel across the world. Of late, there are reports of its absence from a fewer isolates of T. evansi of murine and wildlife origin. Search of literature revealed no reports from horses. The present communication presents the first report of molecular cloning and characterization of Rotat 1.2 VSG from horse isolate of T. evansi from semi-arid region of India. Alongside, the gene was compared with various other isolates across the world. Interestingly, the isolate was found to be closer to camel isolates from Egypt than the other known isolates from India and Kenya.