Cell lines used this study were Vero (ATCC), HeLa-USU [22] , and the P. alecto primary cell lines derived from kidney (PaKi), brain (PaBr), (spleen) PaSp and placenta (PaPl) recently established in our group [27] . Cells were grown in Dulbecco's Modified Eagle's Medium Nutrient Mixture F-12 Ham supplemented with double strength antibiotic-antimycotic (Invitrogen), 10 mg/ml ciprofloxacin (MP Biomedicals) and 10% fetal calf serum at 37uC in the presence of 5% CO 2 .