Table 1.
Characteristics of SB4: Colony types W, S, and C
| Characteristic | Colony type
|
||
|---|---|---|---|
| W | S | C | |
| Capsule size, μm | 3.9 ± 0.8 | 1.3 ± 0.6 | 1.4 ± 0.6 |
| Cell size, μm | 5.9 ± 0.8 | 7.0 ± 0.9 | 5.6 ± 0.7 |
| Doubling times, h | 1.6 | 1.7 | 2.0 |
| AMPHOTERICIN B MIC, μg/ml | 0.25 | 0.25 | 0.125 |
| FLUCONAZOLE MIC, μg/ml | 2 | 2 | 0.5 |
| 5-FC MIC, μg/ml | 4 | 4 | 2 |
| CN survival at −20°C | 0.22 ± 0.10 | 0.07 ± 0.04 | 0.22 ± 0.11 |
| CN survival at 50°C | 0.19 ± 0.11 | 0.04 ± 0.04 | 0.25 ± 0.04 |
| Mean survival of mice, days | 3.2 ± 1.0 | 6.8 ± 1.3 | 11.9 ± 2.2 |
| Inflamatory response | Minimal | Intermediate | Intense caseous necrosis |
| Polysaccharide localization in vivo | E ≫ 1 | E > 1 | 1 > E |
| Antibody response against W extract | N | 76, 70 kDa | 87, 76, 70, 67, 64, 61, 58, 36 kDa |
| Antibody response aganint S extract | N | 76, 70 kDa | 87, 76, 70, 64, 60, 54, 50 kDa |
| Antibody response against C extract | N | 76, 70, 64 kDa | 76, 70, 67, 64, 62, 61, 54 kDa |
Capsule size is expressed as average capsule radius mean ± 1 SD: (n = 40–50) was determined by light microscopy (P value for S versus W is <0.001: P value for C versus S is 0.28). Cell size is average cell diameter (mean ± 1 SD; n = 40–50, not including the capsule) was determined by light microscopy (P value for S versus W is <0.001: P value for C versus W is 0.05). Susceptibility to amphotericin, fluconazole, or 5-fluorocytosine (5-FL) was determined by National Committee for Clinical Laboratory Standards macrodilution method. Survival fraction after overnight exposure to −20° relative to untreated controls represents the average of four experiments P value for S versus W is 0.025; P value for S versus C is 0.049). Survival fraction after exposure to 50°C for 5 min relative to untreated controls represents the average of three experiments (P value for S versus W is 0.09: P value for S versus C is 0.01). Mouse survival experiments were done twice with similar results (P value for C versus S is 0.002; P value for S versus W is 0.003). Inflammatory responses in rats 4 weeks after endotracheal inoculation are shown. Localization of cryptococcal polysaccharide in rat pulmonary model was determined by immunohistochemistry (E, extracellular; I, intracellular). For antibody responses, the molecular weights of major bands recognized by serum IgG in Western blot analysis are shown. Doubling times were determined by CFU experimentation. N, not detected; MIC, minimal inhibitory concentrations.