Related Experiment Videos
Inapparent ocular infection by Chlamydia trachomatis in experimental and human trachoma
A P Hudson1, C M McEntee, M Reacher
1Research Service, Department of Veterans Affairs Medical Center, PA 19104.
Abstract:
There is substantial indirect evidence which suggests that Chlamydia trachomatis can generate inapparent, persistent infections in human. To confirm this directly, we examined ocular chlamydial infection in both the cynomolgus monkey model of trachoma and in patient samples from a trachoma-endemic area. In monkeys, ocular infection was studied over time using direct immunofluorescence cytology (DFA) and a molecular hybridization screening system which targets chlamydial ribosomal RNA. In eleven animals infected once with B serovar, DFA and probe screening of parallel conjunctival swabs gave congruent results through day 42 post-infection. Thereafter, DFA showed clearing of chlamydia and was negative by day 70, as in previous studies. In contrast, hybridization analysis indicated a continuing presence of chlamydial RNA in all samples from all animals through the end of the experiment at day 84 post-infection. Similarly, analysis of swabs from trachoma patients showed that a number of DFA-negative samples gave clear positive signal for chlamydial RNA. Taken together these data indicate that ocular chlamydial infection persists for longer periods than previously thought, judging solely on the basis of DFA, and they support the idea that inapparent ocular chlamydial infection occurs in vivo.
Insights
Chlamydia trachomatis causes persistent, inapparent ocular infections longer than previously detected. Molecular methods reveal chlamydial RNA even when direct tests are negative, confirming subclinical infections.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Microbiology
Background:
- Chlamydia trachomatis is a significant cause of preventable blindness globally.
- Indirect evidence suggests Chlamydia trachomatis can establish persistent, inapparent infections in humans.
- Direct confirmation of persistent ocular Chlamydia trachomatis infection is needed.
Purpose of the Study:
- To directly investigate the duration and persistence of ocular Chlamydia trachomatis infections.
- To compare diagnostic methods for detecting persistent Chlamydia trachomatis in ocular infections.
- To validate the occurrence of inapparent ocular Chlamydia trachomatis infections in vivo.
Main Methods:
- Ocular Chlamydia trachomatis infection was studied in cynomolgus monkeys and human patient samples.
- Direct immunofluorescence cytology (DFA) and molecular hybridization targeting chlamydial ribosomal RNA were used.
- Conjunctival swabs were collected and analyzed over time post-infection.
Main Results:
- Molecular hybridization detected Chlamydia trachomatis RNA in monkey samples through day 84 post-infection, while DFA became negative by day 70.
- Human patient samples also showed positive RNA signals in some instances where DFA was negative.
- These findings indicate Chlamydia trachomatis persists longer than suggested by DFA alone.
Conclusions:
- Ocular Chlamydia trachomatis infections can persist for extended periods, longer than previously recognized based solely on DFA.
- Inapparent ocular Chlamydia trachomatis infections occur in vivo.
- Molecular methods offer enhanced sensitivity for detecting persistent chlamydial infections.