Detection of Chlamydia pneumoniae DNA and Antigen in the Circulating Mononuclear Cell Fractions of Humans and Koalas
Tracy J. Bodetti and Peter Timms*
Centre for Molecular Biotechnology and Co-Operative Research Centre for Diagnostic Technologies, School of Life Sciences, Queensland University of Technology, Brisbane, Australia
Chlamydia pneumoniae is a common respiratory pathogen of humans which, in addition to causing disease at the respiratory site, has recently been linked to disease at other body sites. If C. pneumoniae does contribute to disease at nonrespiratory sites, then it must have a mechanism by which it reaches these sites. We analyzed the peripheral blood mononuclear cell (PBMC) fractions from 60 healthy human blood donors for the presence of C. pneumoniae DNA (by ompA PCR) and chlamydial antigens (by genus- and species-speciﬁc monoclonal antibody staining). Ten of the sixty (16.7%) blood donors were C. pneumoniae positive by PCR, and all 10 of these PCR-positive individuals’ samples demonstrated speciﬁc staining with anti-C. pneumoniae monoclonal antibodies. The only other host naturally infected with C. pneumoniae is the koala, in which the bacterium also causes respiratory infections. We demonstrated the presence of C. pneumoniae DNA and antigens in the PBMC fractions of 30% of 20 koalas tested. Our ﬁnding of C. pneumoniae-infected PBMCs in koalas as well as humans suggests that the ability to infect PBMCs and to disseminate from the respiratory site is not restricted to the human biovar of C. pneumoniae but is a general characteristic of this chlamydial species.