KRT19 and infection: To compare the effects of different antibodies on cell-cell spread of virus within cell columns, we quantified infection in a total of 80 cell columns in sections immunostained for HCMV IE1 and CK19 and found that a low concentration of mAb 2-18 (0.01 μg/mL) reduced infection relative to untreated controls, whereas the higher concentrations of mAbs 3-16, 3-25, and Cytogam had little to no effect (Figure 8B).