Human Chlamydia pneumoniae isolates demonstrate ability to recover infectivity following penicillin treatment whereas animal isolates do not
Anu Chacko1, Kenneth W. Beagley1, Peter Timms1,2 and Wilhelmina M. Huston1,∗
1Institute of Health and Biomedical Innovation, Queensland University of Technology, Q block, 60 Musk Ave, Kelvin Grove, QLD 4059, Australia
2Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, QLD 4558, Australia
∗Corresponding author: Institute of Health and Biomedical Innovation, Queensland University of Technology, Q block, 60 Musk Ave, Kelvin Grove, QLD 4059, Australia. Tel:+61-731386258; Fax:+61-7-31386030; E-mail:
A distinction between human and animal Chlamydia pneumoniae isolates ability to enter a latent phase of growth commonly called persistence is reported in this article. Editor: Mark Schembri
ABSTRACT Chlamydia pneumoniae strains have recently been demonstrated to have substantially different capacities to enter and recover from IFN-γ-induced persistence, depending on whether they are from human or animal host sources. Here, we examined the ability of two human and two animal strains to enter and be rescued from penicillin-induced persistence. The ability to form inclusions after the addition of penicillin was much reduced in the two animal isolates (koala LPCoLN, bandicoot B21) compared to the two human isolates (respiratory AR39 and heart A03). The penicillin treatment resulted in a dose-dependent loss of infectious progeny for all isolates, with the human strains failing to produce infectious progeny at lower doses of penicillin than the animal strains. The most remarkable finding however was the contrasting ability of the isolates to recover infectious progeny production after rescue by removal of the penicillin (at 72 h) and continued culture. The animal isolates both showed virtually no recovery from the penicillin treatment conditions. In contrast, the human isolates showed a significant ability to recovery infectivity, with the heart isolate (A03) showing the most marked recovery. Combined, these data further support the hypothesis that the ability to establish and recover from persistence appears to be enhanced in human C. pneumoniae strains compared to animal strains.