TABLE 3.

Virulence of S. mutans UA130 as a function of GbpA and gtfBC recombinant incidence^a

Strain	Cell recoveryc (mean ± SD)		Mean caries score ± SDb
			Buccal				Sulcal				Proximal
	% Smooth	CFU/ml	E	Ds	Dm	Dx	E	Ds	Dm	Dx	E	Ds	Dm	Dx
wt	0.3 ± 0.9	5.4 × 106 ± 1.6 × 107	13.42 ± 1.4	10.33 ± 1.4	6.58d ± 1.2	5.33 ± 0.9	19.50 ± 2.1	15.08 ± 2.7	9.92 ± 2.2	4.00 ± 2.3	4.50e ± 2.4	1.63 ± 1.7	0	0
gbpA mutant
High gtfBC	22.33 ± 8.3	5.7 × 105 ± 2.9 × 105	14.50 ± 2.1	11.17 ± 1.5	7.83 ± 1.9	5.83 ± 0.8	17.83 ± 2.6	15.67 ± 2.4	8.67d ± 2.6	3.33 ± 1.9	1.67d,e ± 2.6	0	0	0
Low gtfBC	0.17 ± 0.3	4.0 × 106 ± 5.0 × 106	17.67 ± 2.3	13.83 ± 1.7	9.83d ± 2.1	6.3 ± 2.0	22.50 ± 0.8	19.33 ± 1.3	12.00d ± 1.5	8.00 ± 2.1	6.67d ± 1.0	0	0	0

^aData from the S. mutans UA130 wt- and gbpA mutant-infected rats from the restricted diet group. Data from the gbpA mutant-infected rats were divided at the mean level of recombination (14.9%) into a group with a high proportion of gtfBC recombinants (High gtfBC) (n = 6) and a group with a low incidence of recombinants (Low gtfBC) (n = 6). Boldface numbers are statistically higher (P < 0.05) than all others in the same column. 

^bCaries scores as determined by the method of Keyes (6) indicate the relative depths of the carious lesions and the relative areas of the molar surfaces affected by the lesions (numerical score). Abbreviations: E, enamel involvement; Ds, slight dentinal involvement; Dm, moderate dentinal involvement; Dx, extensive dentinal involvement. 

^cS. mutans organisms recovered from rat molar surfaces prior to caries scoring. 

^dScores within the same column bearing the superscript d are statistically different from each other (P < 0.05). 

^eScores within the same column bearing the superscript e are statistically different from each other (P < 0.05).