CD4-AFFINITY PURIFICATION OF RECOMBINANT AND NATIVE HIV GP120 AND COMPARISON OF THE AFFINITY CONSTANTS FOR THE RECEPTOR

Soluble CD4-immunoglobulin chimeric proteins were covalently attached to CNBr-activated Sepharose. This allinity matrix was used to establish a powerful new method to isolate different species of the HIV external glycoprotein gp 120 from cell-free culture supernatants. Recombinant gp 120 was expressed in Baculovirus-infected insect cells and isolated from cell-free culture supernatants. The recombinant protein has an apparent molecular mass of 95 kDa whereas the native gp 120 purified from a persistently HIV-1 infected 119 cell culture has an apparent molecular mass of 130 kDa. These two gp 120 species where shown to be of identical molecular size after complete deglycosylation achieved by endoglycosidase treatment, and they bound to CD4-Hyt with the same binding constant, that was reported for native forms of gp 120 and CD4. Thus the different glycosylation of gp 120 does not influence its allinity to CD4 and the gp 120-CD4 complex can be reversibly dissociated. © 1990.