Gene expression study to elucidate the anti-trypanosomal activity of quinapyramine methyl sulphate (QPS)

The kinetoplastid protozoan parasite, Trypanosoma evansi causes a fatal disease condition known as Surra in equines throughout the globe. Disease condition being acute in nature, entrust a huge economic and health impact on the equine industry. Till date, quinapyramine methyl sulphate (QPS) is the first line of treatment and a panacea for the T. evansi infection in equines. Still after the >70 years of its discovery, there is no clue about the mode of action of QPS in T. evansi. The establishment of in vitro cultivation of T. evansi in HMI-9 media has provided opportunity to study the alteration in mRNA expression of parasite on exposure to the drug. With this research gap, the present study aimed to investigate the relative mRNA expression of 13 important drug target genes to elucidate the anti-trypanosomal activity of QPS against T. evansi. The IC₅₀ of QPS against a pony isolate of T. evansi was determined as 276.4 nM(147.21 ng/ mL) in the growth inhibitory assay. The in vitro cultured T. evansi population were further exposed to IC₅₀ of QPS and their relative mRNA expression was studied at 12 h, 24 h and 48 h interval.The mRNA expression of several genes such as hexokinase, trypanothione reductase, aurora kinase, oligopeptidase B and ribonucleotide reductase II were found refractory (non-significant, p > 0.1234) to the exposure of QPS. Significant up-regulation of trans-sialidase (p < 0.0001), ESAG8 (p < 0.0021), ribonucleotide reductase I (p < 0.0001), ornithine decarboxylase (p < 0.0001), topoisomerase II (p < 0.0021) and casein kinase I (p < 0.0021) were recorded after exposure with QPS. The arginine kinase 1 and calcium ATPase I showed highly significant (p < 0.0001) down-regulation in the drug kinetics. Therefore, the arginine kinase 1 and calcium ATPase I can be explored further to elucidate the trypanocidal activity of QPS. The preliminary data generated provide the potential of arginine kinase 1 and calcium ATPase I mRNA mediated pathway of trypanocidal action of QPS. Further, transcriptomics approach is required to investigate the possible mechanism of action of drugs at molecular level against the targeted organism.