Detection of codon for amino acid 200 in isotype 1 β-tubulin gene of Wuchereria bancrofti isolates, implicated in resistance to benzimidazoles in other nematodes

Albendazole, anthelmintic benzimidazole (BZ) is being co-administered with an antifilarial drug, diethylcarbamazine (DEC), in lymphatic filariasis (LF) elimination programmes. But this drug is known to result in the faster development of drug resistance and hence it is necessary to monitor drug sensitivity among populations of Wuchereria bancrofti. In vitro toxicity assays to detect drug sensitivity are not available for this parasite and hence alternative techniques such as PCR assays need to be developed, for which information on genetic basis for drug sensitivity/resistance is necessary. Such information is lacking in the case of W. bancrofti, but available for nematode parasites of farm animals wherein it has been established that replacement of phenylalanine with tyrosine at amino acid position 200 of β-tubulin isotype 1 conferred BZ-resistance. Using this information we examined the polymorphism in the codon of this residue in W. bancrofti populations representing geographically distant areas of India, through sequencing exon 5 region of β-tubulin isotype 1 gene. The nucleotide sequence data showed that W. bancrofti isolates from wide geographic areas of India had codon for Phe (TTC) at position 200 of the β-tubulin isotype 1 gene suggesting that the parasite might be genetically sensitive to BZ.