<i>RC1339/</i>APRc is expressed in <i>Rickettsia conorii</i> and <i>Rickettsia rickettsii</i> and accumulates at the outer membrane in both species.

<p>(A) RT-PCR analysis of <i>RC1339/</i>APRc expression on rickettsial spp.. The housekeeping gene <i>hrtA</i> (17 kDa surface antigen) was used as a control. The negative control for the cDNA synthesis lacking reverse transcriptase is identified by (RTase -). Rickettsial species are identified on the top and the gene names are shown on the left side of the agarose gel. (B) A whole cell lysate from <i>R. rickettsii</i> (1) and insoluble (2) and soluble (3) fractions from <i>R. conorii</i> extracts were isolated and then subjected to Western Blot analysis with anti-APRc antibody. A specific band with approximately 21 kDa was detected. (C) Whole cell lysates (WCL), inner (IM) and outer membrane (OM) fractions from sarkosyl treatment of <i>R. rickettsii</i> and <i>R. conorii</i> extracts were isolated and then subjected to Western Blot analysis with anti-APRc and anti-rOmpB antibody. APRc shares the same localization of rOmpB, an internal marker for outer membrane of <i>Rickettsia</i> spp. Molecular mass markers in kilodaltons (kDa) are shown on the left. (D) For flow cytometric analysis of APRc expression in <i>R. conorii</i>, fixed bacteria were queried for deposition of anti-APRc (orange trace), negative control lacking primay antibody (blue trace), or the positive control anti-OmpB (red trace), a known rickettsial surface protein. After incubation with fluorescent secondary antibody, both anti-APRc and anti-OmpB detected on the bacterial surface (increased fluorescence), indicating accessibility of these target proteins to exogenously applied antibody.