Characterization of UNC-49 as an Anthelmintic Target in Brugia malayi

Abstract

Brugia malayi is one of several filarial nematodes that pose a health risk to humans. These parasitic nematodes invade humans through infected mosquitoes, who carry the larval form of the worms. Infection leads to lymphatic filariasis – a debilitating disease that involves excess lymph fluid production due to blocked lymphatic ducts and extremely swollen extremities. While there are pre-existing anthelmintic drugs for lymphatic filariasis, there are currently no vaccines or chemotherapy that proves to be adulticidal to Brugia malayi, presenting an urgent need for the development of a new anthelmintic to target the adult worms. We describe the functional expression as well as pharmacological characterization of a homomeric GABAA receptor within adult Brugia malayi, along with the adulticidal potential of piperazine, a GABAA¬ targeting anthelmintic. Phylogenetic analysis comparing host and nematode genes showed that the nematode GABAA receptor is distinctly different, and therefore a potential druggable target. Using RNA extraction, cDNA synthesis, and PCR, we discovered expression of Bma-unc-49 in 3 different isoforms in Brugia malayi adults. We then utilized the patch-clamp technique on whole parasite muscle to confirm the functional expression of this receptor in adult B. malayi somatic muscle cells. Once functional expression was established, we tested piperazine on intact adult male Brugia malayi through the use of the Worminator system and found that piperazine in higher concentrations paralyzes the nematodes transiently, with spontaneous recovery of motility over time. Although piperazine only induces a brief paralysis phase, we suggest that UNC-49 remains a potential anthelmintic target for adult Brugia malayi.