The Bacterial Symbiont Wolbachia Induces Resistance to RNA Viral Infections in Drosophila melanogaster
(A) Two independent sets of isofemales lines were established from VF-0058–3 flies raised on a sub-optimal dose of tetracycline (lines 1–10 and 11–33). The presence of Wolbachia in these lines was tested by PCR amplification using wsp primers on DNA extracts of adult flies, PCR with mt 12S rRNA primers was done as a control. Three–six-d-old males of each line were injected with 500 TCID50 DCV, collected 6 d later, and DCV levels analysed by Western blot with anti-DCV. Anti-tubulin was used as a loading control.
(B) Six wild-type lines infected with Wolbachia (lines 1–6) and six wild-type lines not infected (lines 7–12) were identified by PCR amplification with wsp primers (more information on wild-type lines identity can be found in Materials and Methods). Each stock was treated with tetracycline for two generations and then transferred to tetracycline-free food for at least two generations. Treated and non-treated stocks were re-tested for presence of Wolbachia by PCR amplification with wsp primers. Seven–twelve PCR amplifications were all negative, not shown. Three–six-d-old males of each stock (lines 1–12, tetracycline treated and non-treated) were injected with 500 TCID50 DCV, collected 6 d later, and DCV levels analysed by Western blot with anti-DCV. Anti-tubulin was used as a loading control.