CLONING AND CHARACTERIZATION OF HUMAN RECOMBINANT ANTIBODY FAB FRAGMENTS SPECIFIC FOR TYPE-1 AND TYPE-2 HERPES-SIMPLEX VIRUS

Twenty-six bacterial clones producing human recombinant Fab fragments specific for Herpes Simplex virus (HSV) antigens were obtained from an IgG1k human antibody combinatorial library displayed on filamentous p hage, following panning against an HSV lysate. All the Fabs reacted ag ainst the HSV lysate in enzyme-linked immunosorbent assay and were abl e to recognize both type 1 and type 2 HSV in an indirect immunofluores cence assay (IFA). DNA sequencing of the heavy chain variable regions showed that these Fabs were different from those already described. On e of these Fabs (Fab19) was purified and subjected to further characte rization. Purified Fab19 was able to specifically recognize several di fferent HSV-1 and HSV-2 strains (including 2 reference strains and 12 clinical isolates) in IFA. It was also able to neutralize the infectiv ity of both HSV-1 and HSV-2 strains, although the neutralizing activit y was somewhat lower against HSV-2. In fact, 100% neutralization of in fectivity was observed at a Fab concentration of 2 mu g/100 TCD50 for the majority of HSV-1 strains, while a concentration of 8 mu g/100 TCD 50 was needed for 100% neutralization of all the HSV-2 strains tested. Owing to the above properties, Fab19 appears to be useful for diagnos tic purposes and might also prove useful for in vivo immunoprophylaxis and therapy of HSV infections.