279 - Elucidating the molecular epidemiology of West Nile Virus in Southern Nevada

Abstract: West Nile Virus (WNV) is an RNA virus transmitted by mosquitoes of the Culex genus. The disease caused by this arbovirus is associated with severe outcomes including encephalitis, meningitis, or meningoencephalitis in humans. WNV first appeared in the United States in 1999 and rapidly spread westward reaching Nevada in 2004. Subsequently, WNV has been found annually in the state, including Las Vegas in Southern Nevada. Recent El Niño events have brought unusual precipitation to Las Vegas, altering mosquito-human contact by exacerbating vector breeding. Despite extensive knowledge of WNV in general, little is known about its genetic origins and transmission dynamics in Southern Nevada. A WNV surveillance program is in place in the region, spearheaded by the Southern Nevada Health District (SNHD). SNHD traps mosquitoes during the peak mosquito breeding months of April through October using encephalitis vector surveillance (EVS), Gravid, and BG Sentinel traps. Between March 2023-October 2024, over 12,033 Culex mosquitoes were trapped, and over 388 pools were positive for WNV. In this study, we aimed to uncover the genetic origins of WNV in Southern Nevada using NGS whole genome sequencing techniques. 120 unique pools of WNV RNA were used to synthesize cDNA. These samples were screened for the prevalence of WNV utilizing RT-qPCR, with most samples having CT values from 16-33. A hemi-nested PCR approach was used to enhance the sensitivity and specificity of our technique utilizing primer sets from existing literature. Following amplification, we cleaned our amplicons using AMPure XP beads to remove small DNA fragments to prepare libraries. Prepared libraries were sequenced utilizing the Oxford Nanopore Technologies MinION™️ platform. Final results revealing the genetic origins of WNV Bioinformatic analysis is currently underway, and the results will be presented at the AMCA meeting.