The genetics of ivermectin resistance in <i>Caenorhabditis elegans</i>

TLDR

The ability of organisms to evolve resistance threatens the effectiveness of every antibiotic drug. The study proposes a model that ivermectin sensitivity in *C. elegans* is mediated by parallel GluCl pathways, whose sensitivity is further modulated by unc‑7, unc‑9, and Dyf genes that alter nervous system structure. Simultaneous mutation of avr‑14, avr‑15, and glc‑1 confers high‑level ivermectin resistance, whereas mutating any two genes confers modest or no resistance, suggesting that targeting several members of the multigene family could slow resistance evolution.

Abstract

The ability of organisms to evolve resistance threatens the effectiveness of every antibiotic drug. We show that in the nematode Caenorhabditis elegans, simultaneous mutation of three genes, avr-14, avr-15 , and glc-1 , encoding glutamate-gated chloride channel (GluCl) α-type subunits confers high-level resistance to the antiparasitic drug ivermectin. In contrast, mutating any two channel genes confers modest or no resistance. We propose a model in which ivermectin sensitivity in C. elegans is mediated by genes affecting parallel genetic pathways defined by the family of GluCl genes. The sensitivity of these pathways is further modulated by unc-7 , unc-9 , and the Dyf (dye filling defective) genes, which alter the structure of the nervous system. Our results suggest that the evolution of drug resistance can be slowed by targeting antibiotic drugs to several members of a multigene family.