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Microbes Infect. 2016 Apr;18(4):254-62. doi: 10.1016/j.micinf.2015.12.001. Epub 2015 Dec 17.

Infectious dose and repeated infections are key factors influencing immune response characteristics in guinea pig ocular chlamydial infection.

Author information

1
OCUVAC - Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
2
Department of Research and Development, Institute of Virology, Vaccines and Sera - TORLAK, Belgrade, Serbia.
3
Institute of Environmental Health, Center for Public Health, Medical University of Vienna, Vienna, Austria.
4
OCUVAC - Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria. Electronic address: talin.barisani@meduniwien.ac.at.

Abstract

The aim of this study was to determine whether infectious dose of Chlamydia caviae after repeated infections influences the immunological responses and subsequent clearance of pathogen at the ocular surface of guinea pigs. Animals were infected three times via the conjunctiva at six- and twelve-week intervals by applying either 1 × 10(4) or 1 × 10(6) inclusion-forming units (IFUs) of C. caviae. Ocular pathology, infection course, C. caviae-specific serum IgG levels and their capacity to bind and neutralize infection ex vivo were assessed. Animals infected with 1 × 10(4) IFUs had completely diminished ocular infection and pathology after the 2nd infection with increased levels of C. caviae-specific serum IgG and their effective capacity to bind and neutralize C. caviae. Only partial protection was observed in animals infected with 1 × 10(6) IFUs after the 2nd and 3rd infections. Our findings show that full protection was observed in animals repeatedly infected with the lower dose. The lower dose appeared not to compromise the host immune system, thereby enabling fast clearance of the pathogen and the establishment of competent neutralizing antibodies.

KEYWORDS:

Chlamydia caviae; Guinea pig ocular animal model; Infectious dose; Trachoma

PMID:
26706818
DOI:
10.1016/j.micinf.2015.12.001
[Indexed for MEDLINE]

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