RECEPTOR-BINDING SITES AND ANTIGENIC EPITOPES ON THE FIBER KNOB OF HUMAN ADENOVIRUS SEROTYPE-3

The adenovirus fiber knob causes the first step in the interaction of adenovirus with cell membrane receptors, To obtain information on the receptor binding site(s), the interaction of labeled cell membrane pro teins to synthetic peptides covering the adenovirus type 3 (Ad3) fiber knob was studied. Peptide P6 (amino acids [aa] 187 to 200), to a less er extent P14 (aa 281 to 294), and probably P11 (aa 244 to 256) intera cted specifically with cell membrane proteins, indicating that these p eptides present cell receptor binding sites. Peptides P6, P11, and P14 span the D, G, and I beta-strands of the R-sheet, respectively. The o ther reactive peptides, P2 (aa 142 to 156), P3 (aa 153 to 167), and P1 6 (aa 300 to 319), probably do not present real receptor binding sites . The binding to these sis peptides was inhibited by Ad3 virion and wa s independent of divalent cations, We have also screened the antigenic epitopes on the knob with recombinant Ad3 fiber, recombinant Ad3 fibe r knob, and Ad3 virion-specific antisera by enzyme-linked immunosorben t assay. The main antigenic epitopes were presented by P3, P6, P12 (aa 254 to 269), P14, and especially the C-terminal P16, Peptides P11 and P16 of the Ad3 fiber knob were able to inhibit Ad3 infection of cells .