Isolation and Propagation of Laboratory Strains and a Novel Flea-Derived Field Strain of in Tick Cell Lines.

are intracellular endosymbionts of several invertebrate taxa, including insects and nematodes. Although DNA has been detected in ticks, its presence is generally associated with parasitism by insects. To determine whether or not can infect and grow in tick cells, cell lines from three tick species, , and , were inoculated with strains Stri and AlbB isolated from mosquito cell lines. Homogenates prepared from fleas collected from cats in Malaysia were inoculated into an cell line. Bacterial growth and identity were monitored by microscopy and PCR amplification and sequencing of fragments of genes. The Stri strain infected spp. cells and was maintained through 29 passages. The AlbB strain successfully infected spp. and cells and was maintained through 2-5 passages. A novel strain of belonging to the supergroup F, designated CfeF, was isolated in cells from a pool of sp. cat fleas and maintained in vitro through two passages over nine months. This is the first confirmed isolation of a strain from a flea and the first isolation of any strain outside the "pandemic" A and B supergroups. The study demonstrates that tick cells can host multiple strains, and can be added to panels of insect cell lines to improve success rates in isolation of field strains of .