TABLE 2.

Infectivity of the BbΔbb0238 mutant in C3H/HeN mice

Strain and dose (spirochetes)	No. of positive cultures/total							No. of infected mice/total	ID50
	Ear punch	Back skin	Lymph nodesa	Heart	Tibiotarsal tissue	Bladder	All sites
Bb297
102	1/10	1/10	1/10	1/10	2/10	1/10	7/60	2/10
103	5/10	6/10	7/10	7/10	9/10	7/10	41/60	9/10	378b
104	7/10	8/10	10/10	8/10	10/10	10/10	53/60	10/10
105	7/10	10/10	10/10	7/10	10/10	10/10	54/60	10/10
BbΔbb0238
102	0/10	2/10	2/10	0/10	1/10	1/10	6/60	2/10
103	0/10e	4/10	4/10	0/10e	2/10e	0/10e	10/60e	4/10	1507c,e
104	0/10e	8/10	8/10	0/10e	3/10e	2/10e	21/60e	9/10
105	0/10e	6/10	9/10	0/10e	2/10e	3/10e	20/60e	10/10
Bbbb0238C
102	1/10	1/10	1/10	1/10	1/10	1/10	6/60	1/10
103	3/10	4/10	4/10	4/10	7/10	3/10	25/60	7/10	234d
104	9/10	10/10	10/10	10/10	10/10	10/10	59/60	10/10
105	7/10	10/10	10/10	10/10	10/10	10/10	57/60	10/10

^aA single brachial and inguinal lymph node were collected from each mouse and cultured together.

^b95% confidence interval (CI); range, 148 to 971 spirochetes.

^c95% CI; range, 617 to 3,690 spirochetes.

^d95% CI; range, 91 to 607 spirochetes.

^eStatistically significant difference relative to Bb297 (P < 0.05).