Reactivity of secreted 51p1 Abs isolated from blood of healthy individuals with CMV cell lysate. (A) CMV- and mock-infected cells were harvested at 96 hours p.i. for Western blot analysis with total immune serum and secreted 51p1 Abs isolated and purified from a healthy CMV-seropositive (Se and 51p1 CMV+, respectively) and 2 CMV-seronegative (51p1 CMV−) individuals, respectively. Final Ab concentration used for the 51p1 Ab preparations was 5 μg/mL, respectively. Actin served as a loading control. (B) EIA analysis of the reactivity of secreted 51p1 Abs (51p1 CMV+ and CMV−) to pUL32, pUL29, and untransfected 293FT cell sonicates in comparison that of the different CLL rAbs, and monoclonal Ab of irrelevant specificity (a-HHV-6). Recombinant pUL32, pUL29, and untransfected 293FT cells were harvested at 48 hours after transfection for EIA analysis with equal amounts of total protein used. All rAbs and mAbs were tested at the same final concentration (10 μg/mL). Immune sera against CMV (Se CMV+) and HSV-2 (Se HSV-2+) served as positive controls and were tested at the same serum dilutions (1:1500) against the different protein preparations. All experiments were done in duplicate and each Ab was tested against the 3 different protein preparations in parallel on the same EIA plate. Mean OD readings for the respective Ab preparations tested to each cell sonicate were compared by the use of 1-way analysis of variance, and a statistically significant difference in signal between groups (P < .05) is denoted by an asterisk.