Wolbachia -induced inhibition of O’nyong nyong virus in Anopheles mosquitoes is mediated by Toll signaling and modulated by cholesterol

Wolbachia -induced inhibition of O’nyong nyong virus in Anopheles mosquitoes is mediated by Toll signaling and modulated by cholesterol

Tags: , , ,
S. Pujhari, G. L. Hughes, N. Pakpour, Y. Suzuki and J. L. Rasgon,  bioRxiv,  10.1101/2023.05.31.543096. 2023.

Enhanced host immunity and competition for metabolic resources are two main competing hypotheses for the mechanism of Wolbachia -mediated pathogen inhibition in arthropods. Using an Anopheles mosquito – somatic Wolbachia infection – O’nyong nyong virus (ONNV) model, we demonstrate that the mechanism underpinning Wolbachia -mediated virus inhibition is up-regulation of the Toll innate immune pathway. However, the viral inhibitory properties of Wolbachia were abolished by cholesterol supplementation. This result was due to Wolbachia -dependent cholesterol-mediated suppression of Toll signaling rather than competition for cholesterol between Wolbachia and virus. The inhibitory effect of cholesterol was specific to Wolbachia -infected Anopheles mosquitoes and cells. These data indicate that both Wolbachia and cholesterol influence Toll immune signaling in Anopheles mosquitoes in a complex manner and provide a functional link between the host immunity and metabolic competition hypotheses for explaining Wolbachia -mediated pathogen interference in mosquitoes. In addition, these results provide a mechanistic understanding of the mode of action of Wolbachia -induced pathogen blocking in Anophelines, which is critical to evaluate the long-term efficacy of control strategies for malaria and Anopheles -transmitted arboviruses. HIGHLIGHTS: Wolbachia inhibits O’nyong nyong virus (ONNV) in Anopheles mosquitoes. Enhanced Toll signaling is responsible for Wolbachia -induced interference of ONNV. Cholesterol suppresses Toll signaling to modulate Wolbachia -induced ONNV interference.