Location: Arthropod-borne Animal Diseases Research
Project Number: 3020-32000-018-013-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Mar 1, 2021
End Date: Feb 28, 2026
Objective 1: Quantify the effects of endosymbionts on Culicoides reproduction, thermotolerance and longevity. Objective 2: Assess Endosymbionts's influence on arboviral replication. Objective 3: Elucidate the symbiotic properties of Endosymbionts through genomics and transcriptomics.
Screening of the Culicoides sonorensis colony suggests natural endosymbiont infection with Rickettsia, Cardinium and Wolbachia. This colony will be maintained at the cooperator's institution. Eggs will be collected and separated according to maternal endosymbiont infection status to create endosymbiont-specific positive and negative isolines. Line-crossing experiments will then take place to assess the potential for cytoplasmic incompatibility (CI) induction (the inability to create viable offspring when infected males mate with uninfected females). CI is a hallmark of current endosymbionts-based control interventions which can allow for both vector population suppression and/or rapid spread of the endosymbionts into a population along with any effects on vector-competence. Vector density, thermotolerance and longevity are all determinants of vectorial capacity. Subsequently, survival times at varying temperatures and the fecundity of individuals in the presence and absence of endosymbionts will also be investigated. Arbovirus titers in biting midges will be assessed in the presence and absence of Endosymbionts after a blood meal containing bluetongue and Schmallenberg viruses, and epizootic hemorrhagic disease virus (USDA-ARS). Through inoculation of Culicoides ovaries, endosymbiont-infected cell lines will be created which will be used as an adjunct to the in vivo system to assess mechanisms of any pathogen interference discovered. Short and long read sequencing technologies will be utilized to complete the draft genomes of endosymbiont strains from Culicoides. In addition, RNAseq technology will be used to quantify host differential gene expression in endosymbiont positive and negative midges with particular focus on the induction of immune system activity that might impact on arbovirus titers.