Bacteriophage WO and virus-like particles in Wolbachia, an endosymbiont ofarthropods

Wolbachia are intracellular symbionts mainly found in arthropods, causing v arious sexual alterations on their hosts by unknown mechanisms. Here we rep ort the results that strongly suggest that Wolbachia have virus-like partic les of phage WO, which was previously identified as a prophage-like element in the Wolbachia genome. Wolbachia (strain wTai) infection in an insect wa s detected with the antibody against Wsp, an outer surface protein of Wolba chia, by fluorescence microscopy and immunoelectron-microscopy for the firs t time. Virus-like particles in Wolbachia were observed by electron-microsc opy. The 0.22-mum filtrate of insect ovary contained DAPI-positive particle s, and PCR analysis demonstrated that a phage WO DNA passed through the fil ter while Wolbachia DNA were eliminated, suggesting that the DAPI-positive particles were phage WO, (C) 2001 Academic Press.