Table 1.

Ab levels to whole gp120 and to CD4bs in sera of mice immunized with envelope proteins that have or lack CD4 binding activity^a

	Immunogen & Adjuvant	n	Anti-gp120 (end-point titer)	Anti-CD4bs (ID50)d
Experiment 1b	No Ag & IFA	2	< 20	< 20
	CD4bs+ Env & IFA	4	> 2500	310 (210–470)e
	CD4bs- Env & IFA	3	> 2500	< 20
Experiment 2c	No Ag & RIBI	6	< 100	< 100
	CD4bs+ Env & RIBI	5	9060 (2500–12500)	2160 (630–5900)
	CD4bs- Env & RIBI	5	> 12500 (12500->12500)	< 100

^aSera were collected two weeks after the final immunizations and tested for reactivity with recombinant gp120_LAI in ELISA.

^bAll mice were B10.A, except for two BALB/c in the second group. Each animal was immunized 4x i.p. with 5 μg of antigen in IFA.

^cAll mice were BALB/c and each was immunized 5x i.p. with 5 μg of antigen in RIBI.

^dSerum dilutions that block CD4 binding to gp120_LAI by 50%.

^eGeometric mean and range of the Ab levels from all mice in each group.