Susceptibility of congenitally immunodeficient mice to a nonencapsulated strain of Cryptococcus neoformans.
The susceptibility of congenitally immunodeficient mice to a nonencapsulated strain of Cryptococcus neoformans (strain M7) was evaluated. Gnotobiotic mice with defined congenital defects in innate immunity (beige) or cell-mediated immunity (athymic) or with combined defects in innate and cellular immunity (beige athymic) were i.v. challenged with C. neoformans M7. The nonencapsulated strain of C. neoformans produced a persistent low-grade infection in the brains of all immunodeficient and immunocompetent mice used in this study. Immunocompetent mice (nu/+;bg/+) and immunodeficient bg/bg mice readily cleared nonencapsulated cryptococci from their kidneys, liver, lungs, and spleen. In contrast to nu/+ mice, nu/nu mice had a reduced capacity to clear nonencapsulated cryptococci from their kidneys and liver after i.v. challenge. Both bg/bg-nu/nu and bg/bg-nu/+ mice developed a low-grade infection in their kidneys, liver, lungs, and spleen, which was maintained throughout the 21-day study. Persistent infections were not due to reversion to an encapsulated state. These data indicate that a capsule may not always be necessary for C. neoformans to survive, in vivo, in tissues of immunodeficient and immunocompetent mice.
Salkowski
C A
CA
Department of Surgery, University of Wisconsin Medical School, Madison.
Balish
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E
D000818:Animals; D016667:Bacterial Capsules / Q000502:physiology; D003453:Cryptococcosis / Q000276:immunology* / Q000473:pathology; D003454:Cryptococcus / Q000472:pathogenicity*; D004198:Disease Susceptibility; D005856:Germ-Free Life; D007153:Immunologic Deficiency Syndromes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014774:Virulence