Sequence Polymorphism of Cytochrome b Gene in Theileria annulata Tunisian Isolates and Its Association with Buparvaquone Treatment Failure

Abstract

BackgroundBuparvaquone (BW 720C) is the major hydroxynaphtoquinone active against tropical theileriosis (Theileria annulata infection). Previous studies showed that buparvaquone, similarly to others hydroxynaphtoquinone, probably acts by binding to cytochrome b (cyt b) inhibiting the electron transport chain in the parasite. Several observations suggested that T. annulata is becoming resistant to buparvaquone in many endemic regions (Tunisia, Turkey and Iran), which may hinder the development of bovine livestock in these areas.Methodology/Principal FindingsIn the present study we sought to determine whether point mutations in T. annulata cytochrome b gene could be associated to buparvaquone resistance. A total of 28 clones were studied in this work, 19 of which were obtained from 3 resistant isolates (ST2/12, ST2/13 and ST2/19) collected at different time after treatment, from a field treatment failure and nine clones isolated from 4 sensitive stocks of T. annulata (Beja, Battan, Jed4 and Sousse). The cytochrome b gene was amplified and sequenced. We identified five point mutations at the protein sequences (114, 129, 253, 262 and 347) specific for the clones isolated from resistant stocks. Two of them affecting 68% (13/19) of resistant clones, are present in the drug-binding site Q02 region at the position 253 in three resistant clones and at the position 262 in 11 out of 19 resistant clones. These two mutations substitute a neutral and hydrophobic amino acids by polar and hydrophilic ones which could interfere with the drug binding capabilities. When we compared our sequences to the Iranian ones, the phylogenetic tree analyses show the presence of a geographical sub-structuring in the population of T. annulata.Conclusions/SignificanceTaken together, our results suggest that the cytochrome b gene may be used as a tool to discriminate between different T. annulata genotypes and also as a genetic marker to characterize resistant isolates of T. annulata.

Current status of tropical theileriosis in Northern Africa: A review of recent epidemiological investigations and implications for control

“…The analysis of the epidemiological situations of tropical theileriosis in the African countries clearly indicates that there is an urgent need to optimize the available control tools and to design more innovative science‐based strategies. The present control measures against tropical theileriosis rely on chemotherapy, tick control using acaricides and improving cattle barns, as well as vaccination with attenuated cell line vaccines (Darghouth et al., ; Gharbi et al., ; Mhadhbi et al, ). Each of these measures has its own benefits, but also constraints.…”

Characterisation of infection associated microRNA and protein cargo in extracellular vesicles ofTheileria annulatainfected leukocytes

“…In some countries, cattle are vaccinated with T. annulata-infected cells, attenuated by prolonged in vitro passage (Ali et al, 2008), but these vaccines carry the continued risk of reversion to virulence and are difficult to produce and deliver. Theileria infection can be controlled by chemotherapy, primarily using buparvaquone, but just as with tick control, drug resistance has been identified (Mhadhbi, Chaouch, Ajroud, Darghouth, & BenAbderrazak, 2015), and the cost of treatment is relatively high. Limiting the spread of infection is possible using externally applied acaricides against the vector, but resistance to these chemicals compromises control (Abbas, Zaman, Colwell, Gilleard, & Iqbal, 2014) and their use has environmental implications.…”

In Vitro Screening of the Open-Source Medicines for Malaria Venture Malaria Box Reveals Novel Compounds with Profound Activities against Theileria annulata Schizonts

“…More recently, the first cases of treatment failures due to resistant parasite populations were reported (13). These treatment failures were shown to be associated with mutations in the Theileria cytochrome b gene encoding the ubiquinone reductase of the respiratory chain (14,15). Another potential target of BPQ is Theileria prolyl isomerase (TaPIN1), since mutations in the gene were demonstrated in BPQ-resistant cell lines (16).…”