RICKETTSIA FELIS - A NEW SPECIES OF PATHOGENIC RICKETTSIA ISOLATED FROM CAT FLEAS

A flea-borne rickettsia, previously referred to as ELB, has been impli cated as a cause of human illness, Using sequence data obtained from a fragment of the citrate synthase gene, we compared ELB, Rickettsia au stralis, R. rickettsii, and R. akari with the louse-borne R. prowazeki i. We tallied 24 base pair differences between ELB and R. prowazekii a nd 25 between R. rickettsii and R. prowazekii; there were 30 base pair differences between R. australis and R. prowazekii and 29 between R. akari and R. prowazekii. We observed 32 differences between Rickettsia typhi and ELB. Sodium dodecyl sulfate-polyacrylamide gel electrophore sis and immunoblot analyses of ELB, with typing sera against R. typhi indicate that ELB surface antigens are more closely related to the fle a-borne R. typhi than to the mite-borne R. akari, On the basis of the results of citrate synthase gene sequence comparisons, as well as prev ious comparisons with 16S rRNA and 17-kDa-protein gene segments, we fo und that ELB is sufficiently genetically distinct from other rickettsi ae to be designated a new species, Rickettsia felis.