Wolbachia wAlbB inhibits bluetongue and epizootic hemorrhagic fever viruses in Culicoides midge cells

Authors: MATTHEWS, MEGAN - Texas Tech University; COVEY, HUNTER - Texas Tech University; Drolet, Barbara; BRELSFOARD, COREY - Texas Tech University

Submitted to: Medical and Veterinary Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2022
Publication Date: 3/10/2022
Citation: Matthews, M.L., Covey, H.O., Drolet, B.S., Brelsfoard, C.L. 2022. Wolbachia wAlbB inhibits bluetongue and epizootic hemorrhagic fever viruses in Culicoides midge cells. Medical and Veterinary Entomology. 36(3):320-328. https://doi.org/10.1111/mve.12569.
DOI: https://doi.org/10.1111/mve.12569

Interpretive Summary: Culicoides midges are blood feeding biting flies that transmit bluetongue virus (BTV) and epizootic hemorrhagic fever virus (EHDV) to livestock and wildlife. Bacteria of the Wolbachia genera have been well characterized in mosquito midguts. This bacteria spreads rapidly through insect populations and has been shown to inhibit the ability of some viruses to multiply, thereby decreasing virus transmission by the mosquito. We produced a stable Wolbachia infection in Culicoides cell cultures and demonstrated an inhibitory effect on BTV and EHDV infection. Our results suggest that Wolbachia may interfere with BTV and EHDV and could be used potentially to inhibit virus transmission by Culicoides midges.

Technical Abstract: Culicoides midges are hematophagous insects that transmit arboviruses of veterinary importance. These viruses include bluetongue virus (BTV) and epizootic hemorrhagic fever virus (EHDV). The endosymbiont Wolbachia pipientis Hertig spreads rapidly through insect host populations and has been demonstrated to inhibit viral pathogen transmission in multiple mosquito vectors. Here, we have demonstrated a replication inhibitory effect on BTV and EHDV in a Wolbachia (wAlbB strain)-infected Culicoides sonorensis Wirth and Jones W8 cell line. Viral replication was significantly reduced by day 5 for BTV and by day 2 for EHDV as detected by real-time polymerase chain reaction (RT-qPCR) of the non-structural NS3 gene of both viruses. Evaluation of innate cellular immune responses as a cause of the inhibitory effect showed responses associated with BTV but not with EHDV infection. Wolbachia density also did not play a role in the observed pathogen inhibitory effects, and an alternative hypothesis is suggested. Applications of Wolbachia-mediated pathogen interference to impact disease transmission by Culicoides midges are discussed.