Murine model of concurrent oral and vaginal Candida albicans colonization to study epithelial host-pathogen interactions - PubMed (original) (raw)
Murine model of concurrent oral and vaginal Candida albicans colonization to study epithelial host-pathogen interactions
Durdana Rahman et al. Microbes Infect. 2007 Apr.
Abstract
We report the creation of a new low-estrogen murine model of concurrent oral and vaginal C. albicans colonization that resembles human candidal carriage at both mucosal sites. Weekly estrogen administration of 5 microg intramuscular and subcutaneously was optimal for enhancement of oral colonization and was essential for vaginal colonization. In BALB/c mice, a number of C. albicans clinical isolates (n=3) colonized both oral and/or vaginal sites, but only strain 529L colonized 100% of mice persistently for over 5 weeks. Laboratory strains SC5314 and NCPF 3153 did not colonize the model; however, NCPF 3156 showed vaginal colonization up to week 5. Prior passaging through mice enhanced subsequent colonization of SC5314. Intranasal immunization with a C. albicans virulence antigen (secreted aspartyl proteinase 2) significantly reduced or abolished the fungal burden orally and vaginally by week 2 and 7. Our concurrent model of mucosal colonization reduces the numbers of experimental mice by half, can be used to assess potential vaccine candidates, and permits the detailed analysis of host-fungal interactions during the natural state of Candida colonization.
Conflict of interest statement
The authors have no conflicting financial interests.
Figures
Fig. 1
Persistent oral and vaginal colonization is dependent on both strain of mouse and strain of C. albicans. Three strains of mice (Balb/c, DBA/2 and C57BL/6) (n = 6) were induced into a state of pseudoestrus (see Section 2). Mice were inoculated orally and vaginally as described with two strains of C. albicans, the clinical human isolate 529L and the laboratory strain SC5314. Oral swabs and vaginal washings were collected at weekly intervals and C. albicans CFU/ml in individual mice are shown at 1 and 5 weeks after inoculation. C. albicans NCPF 3153 provided similar data to SC5314 (not shown). Experiments were repeated on at least two occasions with similar results.
Fig. 2
Persistent vaginal colonization by C. albicans 529L requires estrogen. One week after administration of estrogen or saline (see Section 2), Balb/c mice (n = 6) were inoculated vaginally with C. albicans 529L (clinical human isolate) or C. albicans NCPF 3153 (laboratory strain). Weekly vaginal washings were collected and CFU/ml determined (mean ± S.E.M.). Similar data were observed using C57BL/6 mice (not shown). Experiments were repeated on at least two occasions with similar results.
Fig. 3
Fresh isolation of a C. albicans strain from an in vivo site is not a fundamental criterion in order to establish colonization. BALB/c mice (n = 5) were induced into a state of pseudoestrus and inoculated orally and vaginally as described with two clinical C. albicans isolates, GM2093 and GM1055, and the laboratory strain NCPF3156. Oral swabs and vaginal washings were collected at weekly intervals and C. albicans CFU/ml in individual mice are shown at 1 and 5 weeks after inoculation. All three strains colonized both sites at week 1, but at week 5 one or both mucosal sites only in up to 60% of mice and less persistently than 529L (compare with Fig. 1).
Fig. 4
Representative photomicrographs of histological sections of test and control animals. (A, B) Coronal sections through the vagina of estrogen-treated (A) and untreated (B) animals at 3 weeks post-inoculation. (C–E) Histological sections through the oral cavity of estrogen treated animals at 2 weeks (C), 3 weeks (D) and 5 weeks (E) post-inoculation. The inset demonstrates the whole-mount coronal section and the boxed area represents the intra-oral site of colonization by C. albicans 529L (A, buccal mucosa; B, floor of mouth; C, Lingual alveolar mucosa). (F–H) Histological coronal sections through the vagina of estrogen-treated animals at 2 weeks (F), 3 weeks (G) and 5 weeks (H) post-inoculation. Scale bars = 100 μm.
Fig. 5
Passaging of laboratory strain C. albicans SC5314 enhances colonization both orally and vaginally. Estrogen-treated C57BL/6 mice (n = 6) were inoculated with C. albicans SC5314 both orally and vaginally as described. After 1 week, only 2/6 mice were colonized orally and 1/6 vaginally. A single C. albicans colony (encircled) was taken from the oral and vaginal cultures, regrown, and reintroduced into the oral or vaginal cavities, respectively, of the same six mice at week 2. Oral swabs (O/S) and vaginal washings (V/W) were collected for a further 3 weeks. CFU/ml for weeks 1, 2, 3 and 5 are shown. Non-passaged SC5314 did not colonize the model at weeks 3–5 (data not shown).
Fig. 6
Fungal burdens are significantly reduced after mucosal immunization with a putative C. albicans virulence factor. Balb/c mice (n = 10) induced into a state of pseudoestrus (see Section 2) were immunized intranasally with 5 μg of C. albicans secreted aspartyl protease (Sap2) and 1 μg cholera toxin or PBS (control). Two weeks after immunization, mice were challenged orally and vaginally with C. albicans 529L as described. Weekly oral swabs and vaginal washings were collected and fungal burdens followed for an additional 5 weeks (mean ± S.E.M.). Significant reduction in fungal burdens was observed orally at week 2 (*P < 0.05) and at week 7 both orally (**P < 0.001) and vaginally (**P < 0.0001). The data are representative of two independent experiments.
References
- de Repentigny L. Animal models in the analysis of Candida host–pathogen interactions. Curr Opin Microbiol. 2004;7:324–329. - PubMed
- Rahman D, Challacombe SJ. Oral immunization against mucosal candidiasis in a mouse model. Adv Exp Med Biol. 1995;371B:1663–1666. - PubMed
- Rahman D, Mistry M, Challacombe SJ. Mucosal antibodies to Candida antigens in saliva and vaginal secretions after intranasal immunisation. J Dent Res. 1997;76:328.
Publication types
MeSH terms
LinkOut - more resources
Full Text Sources
Molecular Biology Databases