TABLE 1.

DTH responses at day 56

Primary infection	Mean (SD) increase in footpad thicknessa in response to:		Pb
	MoPn antigen	HeLa 229 antigen
MoPn	7.1 (0.5)	1.3 (0.5)	<0.0001
Serovar A	2.9 (1.8)	0.3 (0.4)	<0.02
Serovar E	5.3 (1.1)	0.2 (0.2)	<0.0001
Serovar L2	3.6 (1.8)	0.2 (0.3)	<0.003

^aIncrease in footpad thickness (in millimeters) was measured at 24 h after injection of 5 μg of MoPn antigen and is the mean of 5 mice. Responses in all mice had significantly diminished by 72 h. 

^bBy two-tailed t test.