Publications

4364

Abstract Culicoides biting midges (Diptera: Ceratopogonidae) are vectors responsible for the transmission of several viruses of veterinary importance. Previous screens of Culicoides have described the presence of the endosymbiont Candidatus Cardinium hertigii (Bacteroidetes). However, any impacts of this microbe on vectorial capacity, akin to those conferred by Wolbachia in mosquitoes, are yet to be uncovered and await a suitable system to study Cardinium ‐midge interactions. To identify potential candidate species to investigate these interactions, accurate knowledge of the distribution of the endosymbiont within Culicoides populations is needed. We used conventional and nested PCR assays to screen Cardinium infection in 337 individuals of 25 Culicoides species from both Palearctic and Afrotropical regions. Infections were observed in several vector species including C. imicola and the Pulicaris complex ( C. pulicaris , C. bysta , C. newsteadi and C. punctatus ) with varying prevalence. Phylogenetic analysis based on the Gyrase B gene grouped all new isolates within ‘group C’ of the genus, a clade that has to date been exclusively described in Culicoides . Through a comparison of our results with previous screens, we suggest C. imicola and C. sonorensis represent good candidates for onward study of Cardinium‐ midge interactions.

Abstract“Candidatus Liberibacter asiaticus” (Ca. L. asiaticus) is the causal agent of Huanglongbing disease of citrus and current study focuses on the discovery of novel small‐molecule inhibitors against SecA protein of Ca. L. asiaticus. In this study, homologous modeling was used to construct the three‐dimensional structure of SecA. Then, molecular docking‐based virtual screening and two rounds of in vitro bacteriostatic experiments were utilized to identify novel small‐molecule inhibitors of SecA. Encouragingly, 93 compounds were obtained and two of them (P684‐2850, P684‐3808) showed strong antimicrobial activities against Liberibacter crescens BT‐1 in bacteriostatic experiments. Finally, molecular dynamics simulations were employed to explore the binding modes of the receptor–ligand complexes. Results in MD simulations showed that compound P684‐3808 was relatively stable during simulation, while compound P684‐2850 left the binding pocket. Compound P684‐3808 might be suitable as a lead compound for further development of antimicrobial compounds against SecA of Ca. L. asiaticus.

Recent advances in sequencing technology promoted the blowout discovery of super tiny microbes in the Diapherotrites , Parvarchaeota , Aenigmarchaeota , Nanoarchaeota , and Nanohaloarchaeota (DPANN) superphylum. However, the unculturable properties of the majority of microbes impeded our investigation of their behavior and symbiotic lifestyle in the corresponding community.