Spontaneous change from overt to covert infection of Chlamydia pecorum in cycloheximide-treated mouse McCoy cells

Area of Science:

• Veterinary Microbiology
• Infectious Diseases
• Bacterial Pathogenesis

Background:

• Chlamydia pecorum is an important pathogen in livestock, particularly sheep.
• Chlamydial infections can cause significant economic losses in animal agriculture.
• Understanding chlamydial growth dynamics is crucial for diagnostics and control.

Purpose of the Study:

• To investigate the in vitro growth characteristics of Chlamydia pecorum isolates from sheep feces.
• To compare the behavior of Chlamydia pecorum with Chlamydia psittaci in cell culture models.
• To identify potential differences in chlamydial replication and inclusion formation.

Main Methods:

• Isolation of Chlamydia pecorum from sheep fecal samples.
• Isolation of Chlamydia psittaci from sheep abortion cases.
• Inoculation of cycloheximide-treated cell monolayers with chlamydial isolates.
• Observation of inclusion formation and chlamydial recovery over several weeks.

Main Results:

• Certain Chlamydia pecorum isolates failed to form inclusions immediately upon passage in cell culture.
• Chlamydiae from these specific Chlamydia pecorum isolates were recoverable several weeks post-inoculation.
• Chlamydia psittaci isolates from sheep abortions did not exhibit this delayed inclusion formation phenotype.

Conclusions:

• Chlamydia pecorum exhibits variable in vitro growth patterns, including delayed inclusion development.
• This phenomenon may represent a unique characteristic of certain Chlamydia pecorum strains.
• Differences in growth dynamics between Chlamydia pecorum and Chlamydia psittaci warrant further investigation.