Simkania negevensis strain Z(T): growth, antigenic and genome characteristics

Simkania negevensis is the type species of Simkaniaceae, a recently propose d family in the order Chlamydiales. In the current study, growth, antigenic and genomic characteristics of this intracellular bacterium were investiga ted and compared to those of members of the family Chlamydiaceae. Growth of the organism, as assessed by infectivity assays, reached a plateau in 2-3 d although by light microscopy the cytopathic effect on the host cells incr eased for 12 or more days after infection. S. negevensis growth was unaffec ted by sulfadiazine. Cells infected by S. negevensis strain Z(T) were not r ecognized by either of two monoclonal antibodies specific for Chlamydiaceae LPS and several specific Chlamydiaceae ompA primers were unable to PCR amp lify a S. negevensis gene. The S. negevensis genome contained one copy of t he ribosomal operon. The genome size of S. negevensis strain Z(T) was deter mined by PFGE to be 1.7 Mbp, and the G+C content was 42.5 mol%. These data, taken together with other published data, are consistent with the proposal that S. negevensis belongs to a distinct family in the order Chlamydiales.