Parachlamydia acanthamoebae enters and multiplies within human macrophages and induces their apoptosis [corrected].
Parachlamydia acanthamoebae is an obligately intracellular bacterium that naturally infects free-living amoebae. It is a potential human pathogen and may survive in human macrophages. We studied P. acanthamoebae entry into, and multiplication within, human monocyte-derived macrophages. After 8 h of incubation, 80% of macrophages were infected with a mean of 3.8 P. acanthamoebae organisms per cell. Electron microscopy demonstrated that parachlamydiae were in an intracellular vacuole. After infection with living organisms, the number of parachlamydiae per macrophage increased 4 times from day 0 to day 4, whereas heat-inactivated parachlamydiae were eliminated during the same period. Quantitative PCR confirmed that P. acanthamoebae replicates within macrophages. Transcriptional activity of P. acanthamoeba was detected by reverse transcription-PCR targeting the gene encoding ADP-ATP translocase (tlc). P. acanthamoebae exerted a cytopathic effect on macrophages. When macrophages were infected with living bacteria, their number decreased significantly from day 0 to day 4 due to apoptosis, as shown by annexin-V binding and electron microscopy. This study shows that P. acanthamoebae enters and multiplies within human macrophages before inducing their apoptosis.
D017209:Apoptosis; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002695:Chlamydiales / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity* / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D066298:In Vitro Techniques; D008264:Macrophages / Q000382:microbiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D000226:Mitochondrial ADP, ATP Translocases / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014617:Vacuoles / Q000382:microbiology / Q000648:ultrastructure
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D000226:Mitochondrial ADP, ATP Translocases