Monoclonal Antibodies to HTLV-III451gp41: Delineation of an Immunoreactive Conserved Epitope in the Transmembrane Region of Divergent Isolates of HIV-1

Abstract
We report on the development of monoclonal antibodies directed against the transmembrane portion of the envelope of HTLV-III451 gp41. One of these monoclonal antibodies, designated M71/2B4, was found to cross-react with transmembrane proteins from other independent isolates of HIV-1, namely IIIB, MN, and RF. Thus, this monoclonal antibody identifies an epitope located in a region of gp41 that is conserved among all these isolates. To identify this conserved region a series of E. coli recombinant proteins were screened in immunoblot with M71/2B4. From these results the epitope recognized by this antibody appears to map at the amino terminus of gp41, in the region indicated between the cleavage site with gp120 (aa 508) and the HindIII site (aa 647).