Identification and stage-specific expression of two putative P-glycoprotein coding genes in Onchocerca volvulus.
The potential for the development of ivermectin (IVM) resistance in microfilariae of Onchocerca volvulus and the existence of IVM tolerance in adult worms of this human pathogen are major concerns for the effective control of onchocerciasis. P-glycoprotein (P-gp), an ATP-binding transporter protein associated with multidrug resistance in mammals, protozoa and the nematode, Haemonchus contortus, might play important roles in the development of IVM resistance and/or in the tolerance of adult O. volvulus. In order to find the homologues of P-gp in O. volvulus, reverse transcription polymerase chain reaction (RT-PCR) has been performed in a specially synthesized cDNA pool and two full-length cDNAs have been cloned and sequenced. The first, ovpgp-1, encodes a 1278-amino-acid putative protein (OVPGP-1) with tandemly duplicated halves, each containing six putative transmembrane motifs and an ATP-binding cassette. OVPGP-1 is most similar in sequence to other eukaryotic P-gps. The second cDNA, ovplp-1, encodes a 587-amino-acid P-gp-like protein, which is only half the size of typical P-gps although it still shares high homology with them. Expression patterns of the two genes in different developmental stages have been investigated by semiquantitative RT PCR, suggesting that the expression levels of the two genes (especially ovpgp-1) may be linked with IVM sensitivity; low levels were found in IVM sensitive larval stages while high levels were found in IVM tolerant adult worms.
Huang
Y J
YJ
Institute of Parasitology, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
Prichard
R K
RK
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004351:Drug Resistance; D005369:Filaricides / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D006801:Humans; D007559:Ivermectin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D017181:Onchocerca volvulus / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D017422:Sequence Analysis, DNA
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018076:DNA, Complementary; D005369:Filaricides; D007559:Ivermectin