Design and production of HIV envelope glycoprotein trimers for vaccine and structural studies

The envelope glycoprotein (Env) complex of HIV-1 is the principal focus of neutralizing antibody-based vaccines. The functional Env complex is a trimer consisting of six individual subunits (3 gp120?s, 3 gp41?s), which held in association by relatively weak, non-covalent interactions. The individual subunits are useless as vaccines, because they do not resemble the structure of the functional Env complex. The hypothesis is that a better mimic of the virion-associated Env complex will be able to induce neutralizing antibodies more efficiently than the individual subunits. We have stabilized the native trimeric Env complex by genetic engineering. The resulting soluble Env protein, designated SOSIP gp140 is properly cleaved at the proteolysis site between gp120 and gp41, it has gp120 stably linked to gp41 by an intermolecular disulfide bond, and its trimer interactions are stabilized by a single amino-acid substitution in gp41. Preliminary immunogenicity experiments are encouraging, and this molecule will serve as the lead molecule for the current proposal. The current proposal has two major aims. First, we propose to modify our prototype Env to improve its immunogenicity and structural characterization. Second, we propose to develop an adequate system for the efficient expression of our trimer constructs. The proposed study is a new research line that will be performed in the laboratory of Ben Berkhout at the AMC, but with close interactions with the laboratories of John Moore (Weill Medical College of Cornell University, New York) and Ian Wilson (the Scripps Research Institute, San Diego) for application of Env trimers in vaccine studies and crystallographic studies, respectively.