Single-Nucleotide Polymorphism Associates' ß-Tubulin Isotype-1 Gene in Onchocerca volvulus Populations in Ivermectin-Treated Communities in Taraba State, Nigeria.

ABSTRACT

PURPOSE: The occurrence of Single-Nucleotide Polymorphisms (SNPs) associated with repeated ivermectin treatment and sub-optimal responses reported by previous findings is of great concern in Onchocerciasis endemic areas. This study investigated SNPs' occurrence after 15 years of ivermectin intervention in Onchocerciasis endemic communities in two Local Government Areas of Taraba State, Nigeria. METHODS: Microfilariae samples were collected by skin snip from individuals treated with ivermectin for 10-15 years of annual distribution and preserved in RNAlater® in a 1.5 ml micro-centrifuge tube. Genomic DNA was extracted from microfilariae and residual skin, amplification in two regions within the ß-tubulin gene, sequenced and analyzed for SNPs using Bioinformatics tools. RESULTS: Three distinct SNP positions 1183 (T/G), 1188 (T/C) and 1308 (C/T) on the ß-tubulin gene on the targeted 1083-1568 bp fragment, associate's with the ivermectin-treated population. Furthermore, SNPs positions detected in this study are 1730 (A/G) and 1794 (T/G) in the ß-tub gene in the 1557-1857 (bp) region. The 1794 (T/G) SNP position (Phe243Val) in the exon within the ß-tubulin gene region were observed in this study. CONCLUSION: The present study indicates that SNPs are observed in Onchocerca volvulus, thus strengthening the warning that genetic changes could occur in some parasite populations in some ivermectin-treated areas.