IMPACT OF MIDGUT BACTERIA ON AEDES ALBOPICTUS VECTOR COMPETENCE FOR LA CROSSE VIRUS

Abstract

La Crosse encephalitis is a pediatric illness caused by mosquito-borne La Crosse virus (LACV) and is endemic in western North Carolina. Mosquito control is the only defense against this disease. Not all mosquitoes can transmit LACV. Hence, risk assessments must be improved to target control efforts and protect public health. Midgut bacteria may impact the ability of mosquitoes to become infected with and transmit viruses, i.e. vector competence. Therefore, our pilot study sought to characterize the extent to which mosquito midgut bacteria impacts infection and dissemination rates (proxy for transmission rate) for LACV. We developed methodology to determine the antibiotic dose necessary to suppress midgut bacteria growth using the following groups: 1) no antibiotic; 2) low dose antibiotic; 3) high dose antibiotic. Antibiotics were administered to mosquitoes via sugar meal three days prior to midgut dissection and exposure to LACV. A subset of mosquito midguts was dissected and bacteria cultured for each group prior to delivering a LACV-infected blood meal. Surviving mosquitoes were collected at 14 days post-blood meal. Bodies and legs were separated and stored at -70°C until further processing (i.e. viral RNA extraction and qRTPCR). RNA extractions have been completed and analysis of LACV presence/absence and quantification is underway. This research is part of a larger study examining the overall role of mosquito midgut bacteria in vector competence. This study will ultimately help facilitate future experiments to evaluate impacts of varying levels of midgut bacteria diversity on vector competence.