Further evidence for a link between melarsoprol resistance and P2 transporter function in African trypanosomes

Abstract

In the last few years, several reports have linked resistance to melaminophenyl arsenicals or diamidines in African trypanosomes to the loss or alteration of the P2 purine transporter [1–6]. This link was first established by Carter and Fairlamb [1]. They identified two adenosine transporters in Trypanosoma brucei brucei bloodstream forms, designated P1 and P2, that also mediated the uptake of inosine and adenine, respectively [1]. The P2 transporter exhibited a high affinity for melarsoprol, and both adenosine and adenine, but not inosine, protected bloodstream forms of trypanosomes from melarsen oxide-induced lysis in vitro. Interestingly, P2 transporter activity was not detectable in the melarsoprol-resistant clone RU15 [1]. These results suggested that the clinically important melaminophenyl arsenical drugs are substrates for the P2 adenosine/adenine transporter and as such RU15 should be useful in further delineating the role of nucleoside transporters in drug uptake. In order to investigate any additional changes in purine and drug uptake in melarsoprol-resistant clones, stabilates of RU15 were obtained from Professor A.H. Fairlamb (Dundee, UK) and grown in mice (BALB/c). The authenticity of the strain was investigated using PCR-based analysis of a hypervariable, tandemly repeated sequence that can be used as a genetic Abbre6iations: LSHTM, London School of Hygiene and Tropical Medicine; PCR, polymerase chain reaction; tbms, T. brucei minisatellite; UKC, University of Kent at Canterbury. * Corresponding author: Tel.: +44-1227-827581; fax: +441227-763912. E-mail address: s.m.jarvis@ukc.ac.uk (S.M. Jarvis) 1 Present address: Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.