FIG. 4.

Expression of different HIV gp145 (HXB2/BaL chimera) V region mutants and induction of neutralizing antibodies. (A) Expression of the indicated HXB2/BaL V region mutants was determined by SDS-PAGE followed by Western blotting with transfected 293 cells. (B) Neutralizing activity against BaL in sera from guinea pigs immunized with the indicated DNA/Ad expression vectors. Sera were tested at a 1:5 dilution. Results are the means ± standard errors of four guinea pig sera for each construct. The P value shown is the result of a Mann-Whitney test comparing the median neutralization value of the two groups indicated.