FIG 6.

The C. burnetii type 4 secretion system is essential for establishment of infection in Drosophila. (A) S2 cells were infected with NMII clone 4 or the ΔdotA or ΔpmrA mutant (MOI = 100 GE/cell), and bacterial growth was assessed by qPCR. (B) S2 cells were infected with NMII clone 4 or the ΔdotA and ΔpmrA mutant expressing GFP. CCV formation was observed by confocal microscopy at 6 days postinfection. (C) Coxiella antigens were examined in S2 cells by immunoblotting using an anti-Coxiella polyclonal antibody at 6 and 12 days following infection with NMII clone 4 or the ΔdotA and ΔpmrA mutants. Nonspecific (n.s.) banding in S2 cell lysates is denoted by the arrow. (D) Four-day-old adult Oregon-R flies were infected with 100 GE/fly of NMII clone 4 or the ΔdotA or ΔpmrA mutant, and mortality was monitored for 30 days. The asterisks denote statistical significance (*, P < 0.05). The error bars indicate standard deviations.