HUMAN MONOCLONAL ANTI-HCMV NEUTRALIZING ANTIBODY FROM PHAGE DISPLAY LIBRARIES

Human cytomegalovirus (HCMV) infection in immunocompromised patients c auses considerable morbidity and mortality. Although ganciclovir proph ylaxis reduces the incidence of HCMV disease, severe side effects rais e serious problems. Thus, the development of new strategies for prophy laxis are clearly needed, and human monoclonal antibodies offer a pote ntial alternative. We describe the cloning, using the phage display sy stem, of a recombinant human Fab fragment against HCMV. A phage displa y library with 4 x 10(6) clones was panned three times against lysates of HCMV-infected cells, and screened by ELISA. Of six antigen-binding clones, one monoclonal antibody reacted strongly to HCMV. In immunost aining analysis, this Fab was able to stain HCMV-infected cells from 2 4 h post-infection (pi) through to 96 h pi, but not at 6 h pi. In the presence of cytosine arabinoside, HCMV-infected cells were not stained , even at 24 h pi. These results indicate that an HCMV protein that wa s recognized by the Fab was synthesized in the late phase of infection . In addition, this Fab exhibited neutralizing activity; at 1 mu g/ml it reduced HCMV plaque formation by 50%. The Fab was able to neutraliz e three HCMV strains, but it did not neutralize HSV-1 or -2 infection. (C) 1998 Elsevier Science B.V. All rights reserved.