Alterations in cytochrome-c oxidase expression between praziquantel-resistant and susceptible strains of Schistosoma mansoni
The genetic differences between praziquantel-resistant (R) and susceptible (S) strains of Schistosoma mansoni (Fallon & Doenhoff, 1994) were explored using RAPD and by cloning differentially expressed mRNAs by subtractive PCR. No differences between the 2 strains were detectable by RAPD using 41 different primers indicating that no major genomic rearrangements were present. Subtractive PCR generated a number of fragments, 1 of which was shown to correspond to an over-expressed mRNA in the R strain and to encode a fragment of the subunit 1 of cytochrome-c oxidase (SCOX1). In the absence of a complete sequence for this gene, we used EST sequences to compile a consensus sequence for the 904 bp at the 3′ end that enabled us to choose primers for semi-quantitative RT–PCR. This technique showed that SCOX1 was indeed over-expressed about 5 to 10-fold in the R strain whereas the genes encoding the 28 kDa glutathione S-transferase, glutathione peroxidase, NADH dehydrogenase subunit 5 and the ATP-binding cassette family protein SMDR2 were not. In contrast, cytochrome-c oxidase enzyme activity was 4-fold lower in the R strain than in the S strain.(Received November 20 1997)
(Revised February 5 1998)
(Accepted February 5 1998)
Key Words: Schistosoma mansoni; praziquantel; resistance; EST; cytochrome-c oxidase.
c1 Corresponding author: INSERM U 167, Institut Pasteur de Lille, 59019 – Lille, France. Tel: +33 3 20877783. Fax: +33 3 20877888. E-mail: Raymond. Pierce@pasteur-lille.fr.
p1 Present address: Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, UK.