Interferon-gamma mediates long-term persistent Chlamydia psittaci infection in vitro.
The long-term anti-chlamydial effects of recombinant ovine interferon gamma (rOvIFN-gamma) were studied in ovine ST-6 fibroblasts infected with the S26/3 strain of Chlamydia psittaci. Chlamydial multiplication was assessed by enzyme-linked immunosorbent assay analysis of supernate lipopolysaccharide, titration of inclusion-forming units in culture supernates, and enumeration of inclusion bodies in cultured cells at 7-day intervals. Concentrations of 250 and 1000 U/ml of rOvIFN-gamma resulted in a microbistatic inhibition of C. psittaci growth, which appeared to become microbicidal when rOvIFN-gamma was maintained in the cultures for 14 days or more. There were no signs of C. psittaci multiplication when cultures were maintained in 25 or 100 U/ml of rOvIFN-gamma. However, subsequent removal of rOvIFN-gamma from these cultures resulted in a re-emergence of viable, infectious chlamydiae, which eventually killed all the fibroblasts. This re-emergence was more rapid in cultures initially treated with 25 U/ml of rOvIFN-gamma than in those treated with 100 U/ml.
Brown
J
J
Moredun Research Institute, Edinburgh, UK.
Entrican
G
G
D000034:Abortion, Veterinary / Q000209:etiology; D000818:Animals; D002460:Cell Line; D002691:Chlamydophila psittaci / Q000187:drug effects* / Q000254:growth & development*; D005260:Female; D005347:Fibroblasts; D007371:Interferon-gamma / Q000009:adverse effects*; D011247:Pregnancy; D009956:Psittacosis / Q000209:etiology / Q000662:veterinary; D011994:Recombinant Proteins / Q000009:adverse effects; D012756:Sheep; D012757:Sheep Diseases / Q000209:etiology
D011994:Recombinant Proteins; D007371:Interferon-gamma