Author: Contreras Garcia M, Walshe E, Steketee PC, Paxton E, Lopez-Vidal J, Pearce MC, Matthews KR, Ezzahra-Akki F, Evans A, Fairlie-Clark K, Matthews JB, Grey F, Morrison LJ
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Grant: Tryps3. - Animal trypanosomiasis (AT), caused by Trypanosoma brucei, Trypanosoma vivax, and Trypanosoma congolense, affects millions of animals in particular cattle. The RNA species 7SL sRNA is produced by trypanosomes in infected animals and is a demonstrably reliable diagnostic marker for infection. 7SL sRNA RT-qPCR assays were assessed for cross-reaction with Trypanosoma theileri, and assay performance compared against currently available diagnostic methods by comparing specificity and sensitivity, and assessing the rate of decay of 7SL sRNA following treatment. The assays did not cross-react with T. theileri. The 7SL sRNA RT-qPCR assays specific for T. brucei, T. vivax, and T. congolense performed better than microscopy and DNA PCR in detecting infection. Using a large panel of infected and uninfected samples, species-specific assays were shown to be 100% sensitive and 100% specific for T. brucei, 96.73% sensitive and 99.19% specific for T. congolense, and 93.42% sensitive and 82.43% specific for T. vivax. The 7SL sRNA signal was undetectable or significantly reduced 96 hours after treatment: there was no detectable signal in 5/5 cattle infected with T. congolense and in 3/5 cattle infected with T. vivax—the signal was reduced 14,630-fold in the remaining two cattle infected with T. vivax. Thus, the 7SL sRNA assays have attributes required for a potential diagnostic marker of AT: no cross-reaction with T. theileri, high specificity and sensitivity, early infection detection, continued signal even in the absence of detectable parasitaemia in blood, and clear discrimination between infected and treated animals.
Subject Areas: Research and Development