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Experimental infection with Chlamydia pneumoniae in nonhuman primates
S M Holland1, H R Taylor, C A Gaydos
1Department of Medicine and Dana Center of Preventive Ophthalmology, Wilmer Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
Abstract:
To serially examine the immunopathogenesis and histopathology of infection with Chlamydia pneumoniae, we inoculated two cynomolgus monkeys in the conjunctival sac, nose, and nasopharynx with C. pneumoniae TWAR. After inoculation, C. pneumoniae was isolated from the inoculation sites and the rectums of both monkeys for a period of 5 weeks. After a second inoculation, C. pneumoniae was recovered from the inoculation sites and the rectums of both monkeys for 20 weeks. A third inoculation with C. pneumoniae caused very little productive infection at any site. Prior C. pneumoniae infection did not prevent subsequent C. trachomatis serovar E (Bour strain) infection. Clinical and histopathologic ocular responses to C. pneumoniae infection were mild compared with those to infection with C. trachomatis serovar E. Rectal infection, demonstrated by culture isolation and immunohistopathology, occurred without direct experimental inoculation. Both immunofluorescent staining of mucosal smears with monoclonal antibodies and tissue culture were able to detect C. pneumoniae infection. Experimental nonhuman primate infection with C. pneumoniae appears to be clinically and histopathologically mild and can occur at extrapulmonary sites.
Insights
This study shows that repeated Chlamydia pneumoniae (C. pneumoniae) infections in nonhuman primates lead to mild clinical and histopathologic outcomes. C. pneumoniae can also establish extrapulmonary infections, particularly in the rectum.
Area of Science:
- Infectious Diseases
- Immunology
- Veterinary Pathology
Background:
- Chlamydia pneumoniae (C. pneumoniae) is a significant human respiratory pathogen.
- Understanding its pathogenesis and host immune response is crucial for developing effective interventions.
- Nonhuman primate models offer valuable insights into C. pneumoniae infection dynamics.
Purpose of the Study:
- To investigate the serial immunopathogenesis and histopathology of C. pneumoniae infection in cynomolgus monkeys.
- To evaluate the impact of repeated C. pneumoniae inoculations on infection duration and severity.
- To assess the susceptibility to subsequent C. trachomatis infection after C. pneumoniae exposure.
Main Methods:
- Cynomolgus monkeys were inoculated with C. pneumoniae TWAR strain in ocular, nasal, and nasopharyngeal sites.
- Serial isolation of C. pneumoniae from various sites, including rectum, was performed.
- Immunohistopathology, immunofluorescent staining, and tissue culture were utilized for detection.
- Monkeys were subsequently challenged with C. trachomatis serovar E.
Main Results:
- C. pneumoniae was isolated from inoculation sites and rectums for up to 20 weeks after repeated inoculations.
- Third inoculation resulted in minimal productive infection, suggesting some level of immunity.
- Prior C. pneumoniae infection did not prevent subsequent C. trachomatis infection.
- Ocular and rectal infections were clinically and histopathologically mild compared to C. trachomatis.
- Extrapulmonary rectal infection occurred without direct inoculation.
Conclusions:
- Experimental C. pneumoniae infection in nonhuman primates is generally mild clinically and histopathologically.
- Repeated infections can lead to prolonged shedding and establish extrapulmonary infections, notably in the rectum.
- Nonhuman primate models are suitable for studying C. pneumoniae pathogenesis and immune responses.