TABLE 3.

Mouse infection by nymphal tick transmission of B. burgdorferi strains with ospA promoter fusions^a

Route of larval tick infection	B. burgdorferi strain genotype	No. of mice infected/total no. exposed
SCID mouse blood meal	WT	2/2
	ApospC	2/2
	ApospA	2/2
Immersion	WT	2/2
	ApospC	2/2
	ApospA	2/2
WT mouse blood meal	WT	4/4
	ΔospA	0/2
	ApospC	0/2
	ApospA	2/2
	ApospB	2/2

^aTwenty nymphs per tick cohort were applied to WT mice and were allowed to feed to repletion. Three weeks after the application of ticks, mouse infection was assessed by seroconversion and by isolation from ears, bladders, and joints. Infected animals were seropositive and had at least two tissues positive out of three tissues assessed. Negative animals were seronegative and had no positive tissues.