TABLE 3.
Nasopharyngeal colonization of BALB/cByJ mice by WU2 and D39 derivativesa
| Strain | Capsule productionb (%) | Colonizationc | Nasal washd log CFU/ml (± SEM) |
|---|---|---|---|
| WU2 (type 3 parent) | 100 | 9/13e | 3.49 (0.18) |
| JD770 (insertion control) | 100 | 12/20 | 3.43 (0.25) |
| JY1060 (PGMr) | 20 | 6/10 | 3.47 (0.41) |
| JD614 (Cps3Dr) | <6 | 0/10**f | — |
| JD692 (Cps3Dr) | <0.6 | 0/10**f | — |
| JD908 (Cps3S−) | 0 | 0/10**f | — |
| JD770 + JD908 | Cps+/Cps− | 0/5*f (both)g | — |
| 2/5 (JD770) | 3.60 (0.30) | ||
| D39 (type 2 parent) | 100 | 7/10 | 3.12 (0.28) |
| AM1000(ΔCps2ABCDETFGH) | 0 | 0/10**f | — |
Mice were inoculated i.n. with 1 × 107 (WU2 and derivatives), 4 × 108 (D39), or 9 × 108 (AM1000) CFU.
Values are relative to the appropriate parent strain. WU2 produces approximately 46 μg of cell-associated capsule/ml of culture/unit of optical density at 600 nm (26, 27). Capsule production by its derivatives has been reported previously (20, 26, 27), except for JD614 and JD692, which were reactive with the type 3-specific monoclonal antibody in indirect ELISAs, as indicated. JD908 was nonreactive with antibody to type 3 polysaccharide. Repair or resolution of each of the mutations restores parental levels of capsule and, for JY1060 and JD908, has been shown previously to restore parental virulence following i.p. and i.v. infections (26, 27). The polyclonal antiserum used to detect type 2 capsule reacts with other surface antigens. In the ELISA, the optical density at 405 nm of AM1000 was reduced sixfold from that of D39 and was not significantly different from that of the nonencapsulated type 2 strain R36A (data not shown). Cps+, parental levels of capsule; Cps−, nonencapsulated.
Values are the numbers of mice colonized per total numbers of mice. Except as noted, none were significantly different from the values for the parent.
See footnote d in Table 2. Where bacteria were recovered, none of the values were significantly different from the values for the parent.
Values include colonization by JD600, the WU2 (Strr) derivative used to construct JD614 and JD692.
Significantly different from the value for the parent (*, P < 0.05; **, P < 0.005).
The presence of both strains was distinguished by colony morphology.