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Experimental chlamydial keratitis in rabbits. Correlation with chlamydia infected McCoy tissue culture cells
A M Abu el-Asrar1, P C Maudgal, M H Emarah
1Department of Ophthalmology, Mansoura University Hospital, Egypt.
Abstract:
Rabbit corneas were inoculated three times at weekly intervals with the agent of chlamydia trachomatis using the scratch method. Specimens of the corneal epithelium were obtained using the replica technique on the 1st, 2nd, 3rd and 4th day after each inoculation and at two weeks after the last inoculation. The development of chlamydial inclusions and the inflammatory cell response were monitored using Giemsa stain, acridine orange stain and direct immunofluorescent technique. Primary inoculation produced mild clinical disease associated cytologically with polymorphonuclear leucocytic cellular inflammatory response. Repeated inoculations produced more severe disease associated clinically with pannus formation and cytologically with the presence of lymphocytes and Leber cells in addition to polymorphonuclear leucocytes. Halberstaedter Prowazek inclusion bodies were detected in all the specimens. Additional intracytoplasmic and intranuclear inclusions of different morphological appearances were present. The cytological findings detected in the corneal epithelium of rabbits were correlated with the findings in McCoy tissue culture cells inoculated with chlamydia trachomatis.
Insights
This study tracked Chlamydia trachomatis in rabbit corneas, revealing that repeated infections worsen disease and alter inflammatory responses. Findings correlate rabbit corneal findings with McCoy cell cultures.
Area of Science:
- Ophthalmology
- Microbiology
- Immunology
Background:
- Chlamydia trachomatis is a significant cause of infectious blindness worldwide.
- Understanding the ocular pathogenesis of C. trachomatis is crucial for developing effective treatments.
- Rabbit models are frequently used to study ocular infections, but detailed cytological responses to repeated inoculations require further elucidation.
Purpose of the Study:
- To investigate the cytological and clinical changes in rabbit corneas following repeated inoculation with Chlamydia trachomatis.
- To compare the inflammatory cell response and inclusion body development after primary versus repeated infections.
- To correlate in vivo rabbit corneal findings with in vitro McCoy cell culture results.
Main Methods:
- Rabbit corneas were inoculated with Chlamydia trachomatis via the scratch method at weekly intervals.
- Corneal epithelium specimens were collected at multiple time points post-inoculation.
- Giemsa stain, acridine orange stain, and direct immunofluorescence were used to detect chlamydial inclusions and inflammatory cells; findings were compared to McCoy cell cultures.
Main Results:
- Primary inoculation caused mild disease with a polymorphonuclear leucocytic inflammatory response.
- Repeated inoculations led to more severe clinical disease, including pannus formation, and a mixed inflammatory infiltrate (lymphocytes, Leber cells, polymorphonuclear leucocytes).
- Halberstaedter Prowazek inclusion bodies and other novel intracytoplasmic/intranuclear inclusions were observed.
Conclusions:
- Repeated Chlamydia trachomatis ocular infections in rabbits induce a more severe inflammatory response and clinical pathology.
- The study identified distinct cytological differences between primary and repeated infections, highlighting the role of lymphocytes and Leber cells in later stages.
- The observed cytological findings in rabbit corneal epithelium closely mirrored those in Chlamydia trachomatis-infected McCoy cell cultures.