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Infection and Immunity, February 2000, p. 832-838, Vol. 68, No. 2
Division of Infectious
Diseases,1 Departments of
Pediatrics,2
Pathology,3
Medicine,4 and Microbiology and
Immunology,5 and Children's Hospital at
Montefiore,6 Albert Einstein College of
Medicine, Bronx, New York
Received 21 June 1999/Returned for modification 16 July
1999/Accepted 30 October 1999
Fungal pathogens are notorious for causing chronic and latent
infections, but the mechanism by which they evade the immune response
is poorly understood. A major limitation in the study of chronic fungal
infection has been the lack of suitable animal models where the
infection is controlled and yet persists. Pulmonary Cryptococcus
neoformans infection in rats results in a diffuse pneumonitis
that resolves without dissemination or scarring except for the
persistence of interstitial and subpleural granulomas that harbor
viable cryptococci inside macrophages and epithelioid cells. Infected
rats are asymptomatic but remain infected for as long as 18 months
after inoculation with C. neoformans. Containment of
infection is associated with granuloma formation that can be partially
abrogated by glucocorticoid administration. Using this model, we
identified several features associated with persistent infection in the
rat lung, including (i) localization of C. neoformans to
discrete, well-organized granulomas; (ii) intracellular persistence of
C. neoformans within macrophages and epithelioid cells;
(iii) reduced inducible nitric oxide synthase expression by granulomas harboring C. neoformans; and (iv) reduced antibody
responses to cryptococcal polysaccharide. The results show that
maintenance of persistent infection is associated with downregulation
of both cellular and humoral immune responses.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Persistent Cryptococcus neoformans
Pulmonary Infection in the Rat Is Associated with Intracellular
Parasitism, Decreased Inducible Nitric Oxide Synthase Expression, and
Altered Antibody Responsiveness to Cryptococcal
Polysaccharide
*
Corresponding author. Mailing address: Albert Einstein
College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461. Phone: (718) 430-4259. Fax: (718) 430-8701. E-mail:
dgoldma{at}aecom.yu.edu.
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