Escherichia coli expression, purification, and biological activity of a truncated soluble CD4.

A truncated molecule containing the N-terminal 183 amino acid residues of CD4 (sCD4-183) has been produced in Escherichia coli at high levels, using the trp promoter and an AT-rich ribosome binding site to direct expression in a pBR322-derived vector. A culture has been selected which allows large-scale fermentation and production of this material as an insoluble inclusion body protein. Procedures which solubilize, refold, and purify sCD4-183 have been developed. The purified sCD4-183 binds gp120 in solution and blocks human immunodeficiency virus (HIV) infection of human peripheral blood lymphocytes in vitro.