Melanotic Pathology and Vertical Transmission of the Gut Commensal Elizabethkingia meningoseptica in the Major Malaria Vector Anopheles gambiae (original) (raw)
Figure 3
Pathogenicity, lesion induction and vertical transmission of E . meningoseptica .
(A) Virulence of E . meningoseptica toward mosquitoes. Independent isolates of E meningoseptica (isolates 0 to 4) were injected in adult females. Survival rate is shown as percentage with standard error (n=120 per isolate) from 3 independent assays. Sterile PBS and heat-killed (HK) bacterial cultures were injected as controls. Points indicated by *** are statistically very highly significant (P<0.05) between HK and isolate injected samples. (B) Mosquito survival rate after injection of serial dilutions of E . meningoseptica (isolate 0) as indicated; n=180 from 3 independent assays. Values of HK and live bacterial samples were very highly significantly different (P<0.05). (C) Induced melanotic lesions in the fat body by E . meningoseptica; (Ci) Partially dissected 6-8th abdominal segments after bacterial injection showing massive melanisation of fat body tissues; (Cii) Dissemination of melanotic spots throughout the abdominal fat body; (Ciii) Trail-like melanisation; (Civ) An aggregate with disseminated spots; (Cv) Melanised individual fat body cells (Cvi). A major melanotic thoracic aggregate. Scale bar 0.5mm (Ci, Ciii-Cvi), 0.2mm (Cii). (D) Enrichment of E . meningoseptica in An. gambiae ovaries. E . meningoseptica fed to germ-free females shows colonization of ovaries (E.m), whereas aseptic adults did not show any colony. (E) Mosquito lethality upon bacterial recolonisation. E . meningoseptica (E.m) or whole microbiota (WM) suspensions were fed to germ-free mosquitoes (GF) and survival was assessed 24h later. Non-supplemented GF mosquitoes were used as control. Bars show distribution as percentage (mean value in red with standard error) of dead (black area) and alive (grey area) mosquitoes (n=80) from 2 independent experiments. (F) Plasmodium berghei development is not affected by bacterial reconstitution. E.m, WM and GF mosquitoes were infected with malaria 24h post-reconstitution, and oocyst load monitored 7 days post-infection, represented as oocyst number per midgut (green dot) with mean values as red dotted bar. Mosquitoes were blood-fed on the same infective host (n=120) from 2 independent experiments. No statistical difference was found in between all oocyst load mean values. (G) Synergistic effect on mosquito survival upon bacterial reconstitution and Plasmodium infection. Mosquito survival of malaria infected-Em, -WM and -GF was assessed 24h post-infection.