Interferon-gamma mediates long-term persistent Chlamydia psittaci infection in vitro

J. Brown, Gary Entrican

Research output: Contribution to journalArticlepeer-review


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.
Original languageEnglish
Pages (from-to)373-83
Number of pages11
JournalJournal of Comparative Pathology
Issue number4
Publication statusPublished - Nov 1996


  • Abortion, Veterinary
  • Animals
  • Cell Line
  • Chlamydophila psittaci
  • Female
  • Interferon gamma
  • Pregnancy
  • Psittacosis
  • Recombiant proteins
  • sheep
  • Sheep Diseases

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