Project description:Host-derived factors are sucked into midgut of mosquitoes during natural malaria transmission, but their influence on malaria transmission is largely unknown. We reported that mouse complement C3 taken into mosquitoes significantly promoted malaria transmission either in laboratory or in field. This effect was attributed to the reduction of microbiota abundance in mosquito midgut by host-derived C3 through direct lyses the predominant symbiont bacteria Elizabethkingia anopheles. Elizabethkingia anopheles symbiont bacteria were demonstrated to be detrimental to malaria sexual stages in mosquitoes. Strikingly, the promoted effect of host C3 on malaria transmission was confirmed by laboratory mosquitoes membrane-feeding on Plasmodium falciparum. Therefore, we reveal a novel strategy of malaria parasite to utilize host complement C3 to promote its transmission, and the administration of C3 inhibitor would provide us a novel strategy to control malaria transmission.
Project description:Plasmodium parasites within mosquitoes are exposed to various physiological processes, such as blood meal digestion activity, the gonotrophic cycle, and host responses preventing the entry of parasites into the midgut wall. However, when in vitro-cultured ookinetes are injected into the hemocoel of mosquitoes, Plasmodium parasites are not affected by the vertebrate host’s blood contents and do not pass through the midgut epithelial cells. This infection method might aid in identifying mosquito-derived factors affecting Plasmodium development within mosquitoes. This study investigated novel mosquito-derived molecules related to parasite development in Anopheles mosquitoes. We injected in vitro-cultured Plasmodium berghei (ANKA strain) ookinetes into female and male Anopheles stephensi (STE2 strain) mosquitoes and found that the oocyst number was significantly higher in males than in females, suggesting that male mosquitoes better support the development of parasites. Next, RNA-seq analysis was performed on the injected female and male mosquitoes to identify genes exhibiting changes in expression. Five genes with different expression patterns between sexes and greatest expression changes were identified as being potentially associated with Plasmodium infection. Two of the five genes also showed expression changes with infection by blood-feeding, indicating that these genes could affect the development of Plasmodium parasites in mosquitoes.
Project description:The objective of the study was to uncover the transcriptional differences between B. burgdorferi pleomorphic forms (spirochetes, round bodies, blebs and biofilms).
Project description:Lyme disease spirochetes must induce RpoS-dependent genes during tick feeding to prepare for host infection. Previous work in our lab identified bbd18 as a negative regulator of RpoS, but inactivation of bbd18 in wild-type spirochetes was never achieved. In the current study we generated an inducible bbd18 gene at the endogenous plasmid locus and demonstrated the essential nature of BBD18 for viability of wild-type spirochetes in vitro and at a unique point in vivo. Transcriptomic analyses demonstrated global induction of RpoS and RpoS-dependent genes following BBD18 depletion, culminating in spirochete lysis. Plasmid prophage genes were also induced and phage particles were detected in lysed culture supernatants, suggesting that RpoS regulates phage lysis-lysogeny decisions. The absolute requirement for BBD18 persisted following displacement of the entire set of cp32 plasmid prophages but could be circumvented by deletion of rpoS. This is the first report of a mechanistic link between endogenous transducing prophages and the RpoS-dependent adaptive response of the Lyme disease spirochete.