HTLV-1-specific serologic response in rabbits inoculated with transfected PBMC. Represented are rabbits inoculated once (R50, 53, 57, and 58) or twice (R32 and 33) with ACH- (R53 and 32), ACH.p12- (R57, 58, and 33), or pKS (vector control)- (R50) transfectants. Data shown are absorbance values of plasma samples diluted 1:12,800 and measured by anti-HTLV-1 antibody ELISA (A) or reactivity to specific HTLV-1 antigenic determinants measured by Western blot analysis (B). Note that reactivity of R50 (negative control) on ELISA is nonspecific for HTLV-1 as shown by Western blot analysis and is attributable to cross reactivity of cellular antigens in the inoculum and the ELISA. The data shown for each rabbit are representative of the larger inoculation group. Thus, R32 and R33 represent two rabbits each, R53 represents four rabbits, and R57 and R58 demonstrate two different reaction patterns seen among the four rabbits comprising that inoculant group.