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.

Comparative study of esterases in deltamethrin and diazinon resistant Rhipicephalus microplus and Hyalomma anatolicum ticks collected from the Trans-Gangetic plains of India

A comparative analysis of esterases in susceptible and resistant ticks revealed six types of esterases (EST-1b, EST-2b, EST-3b, EST-4b, EST-5b and EST-6b) in Rhipicephalus microplus and four types (EST-1h, EST-2h, EST-3h, EST-4h) in Hyalomma anatolicum using α-naphthyl acetate substrate. Inhibition studies with eserine sulfate, p-chloromercuribenzoate, copper sulphate and phenylmethylsulfonyl fluoride revealed a marked variation in band intensity between susceptible and resistant ticks, with the latter being more intense. Qualitative expression of EST-4b along with an extra band of EST-5b and EST-6b were indicative of deltamethrin and diazinon resistance in R. microplus, whereas qualitative expression of EST-4h was probably responsible for diazinon resistance in H. anatolicum. The data suggest that increased esterase activity may represent a detoxification strategy leading to the development of resistance in these tick populations.

Acaricide resistance in Rhipicephalus (Boophilus) microplus and Hyalomma anatolicum collected from Haryana and Rajasthan states of India

Acaricide resistance status of Rhipicephalus (Boophilus) microplus and Hyalomma anatolicum ticks against deltamethrin and diazinon was assessed in Hisar (Haryana) and its adjoining district Churu (Rajasthan) using adult immersion test (AIT) and larval packet test (LPT). The mortality slope, LC50, LC95, 95 % confidence limit and resistance factor of field ticks were determined. Results showed that R. (B.) microplus ticks collected from Tohana (Hisar) were found resistant to both the acaricides while the ticks of Agroha (Hisar) were found to be susceptible using AIT. Similar results were observed by using standard method of LPT. Again, H. anatolicum tick isolates of Tara Nagar (Churu) were found susceptible whereas Churu tick isolates were found to be resistant using AIT for both the acaricides. LPT indicated susceptible status of H. anatolicum ticks collected from Churu as well as Tara Nagar for both the acaricides. The study warrants the need for strategic use of available acaricides to overcome the development of acaricide resistance in ticks.

Sexual alteration in antioxidant response and esterase profile in Hyalomma anatolicum anatolicum (Acari: Ixodidae) ticks

The objective of the study was to reveal physiological link between sex specific engorgement pattern and evading mechanism of ticks against oxidative stress as well as acaricides. Quantitative determination of nitric oxide radical scavenging, superoxide dismutase activity and reduced glutathione (GSH) concentrations in salivary gland and gut extracts of male and female Hyalomma anatolicum anatolicum (Acari: Ixodidae) ticks established significant variation in antioxidant responses between two sexes of the ticks. Higher activity of these antioxidants and GSH depletion in females clearly indicate stronger antioxidant defense in female ticks which is to combat host mediated oxidative assault during feeding for greater engorgement and reproductive stress. The females are also better equipped with the mechanism of acaricide resistance as evidenced by higher expression of esterases than males in unfed whole tick extracts in current study.

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

Trypanosomosis or Surra can rightly be attributed as the most economically important vector-borne haemoprotozoan disease encountering India. Surra infected chronic cases show almost similar types of signs and symptoms often confusing it with other haemoprotozoan infections, thereby, making it prerequisite for the development of aspecific and sensitive technique for its detection in susceptible animals. Blood microscopy and serology suffers from the hands of lack of sensitivity and specificity thereby leaving molecular detection techniques as one of the promising alternative. Alongside, there is utmost need for exploring of new molecular gene targets for the development of a putative alternative for diagnosis and immunoprophylaxsis. The present communication describes the identification and amplification of oligopeptidase B, cysteine protease and variable surface glycoprotein genes of T. evansi so as to exploit them in future as potential candidates for immune protection and/or molecular detection.