7th International AIDS Conference Florence, Italy — June 16-21, 1991

Int Conf AIDS 1991 Jun 16-21; 7:99 (abstract no. M.A.1029)
Maino V, Singer R, Buck D, Buchanan T; Becton Dickinson Immunocytometry Systems, San Jose, CA

OBJECTIVE: Synthetic peptides derived from CD4 sequences of the putative binding domain of gp120 were employed in an effort to further characterize the gp120 binding site on CD4.

METHODS: Monoclonal antibodies (MAb) raised against synthetic peptides derived from sequences of the V1 domain were evaluated for their ability to bind native CD4 and to block gp120 and anti-CD4 MAb binding as determined by flow cytometry analysis. In addition we evaluated a panel of monoclonal antibodies with apparent specificity for the V1 domain of CD4 for their ability to bind to a variety of synthetic peptides.

RESULTS: A summary of the MAb reactivities are provided in the table below. These studies indicated that two mabs generated against synthetic peptides from regions 44-58 or 40-55 of CD4 demonstrated specific binding to CD4 as determined by FACS analysis. One of these MAbs, 4E4A (44-58) was capable of binding CD4 at titers comparable to many anti-CD4 mabs raised against native antigen. 4E4A also demonstrated weak but significant blocking activity for both gp120 and the anti-CD4 MAb L83. From a panel of 22 anti-CD4 MAbs capable of blocking gp120 binding, one of these, L204 demonstrated specific reactivity, as determined by peptide ELISA, with CD4 23-55 a 33 residue synthetic peptide derived from the V1 domain of CD4. TABULAR DATA, SEE ABSTRACT VOLUME.

CONCLUSIONS: This analysis suggests the amino acid region of 44-58 of CD4 contains sequences capable of binding both gp120 blocking and non-blocking MAbs and therefore may represent at least a part of the gp120 binding domain.

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