|Title||Structure-guided redesign increases the propensity of HIV Env to generate highly stable soluble trimers.|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Guenaga J, Dubrovskaya V, de Val N, Sharma SK, Carrette B, Ward AB, Wyatt RT|
Due to high viral diversity, an effective HIV-1 vaccine will likely require Envs derived from multiple subtypes to generate broadly neutralizing antibodies (bNAbs). Soluble Env mimetics, like the NFL (native flexibly linked) and SOSIP trimers, derived from the subtype A BG505 Env, form homogeneous, stable native-like trimers. However, other Env sequences, such as JRFL and 16055 from subtypes B and C, do so to a lesser degree. The high-resolution BG505 SOSIP crystal structures permit the identification and redesign of Env elements involved in trimer stability. Here, we identified structure trimer-derived (TD) residues that increased the propensity of the subtype B JRFL and subtype C 16055-Env sequences to form well-ordered, homogenous and highly stable soluble trimers. The generation of these spike mimetics no longer required antibody-based selection, positive or negative. Using the redesigned subtype B and C trimer representatives as respective foundations, we further stabilized the NFL TD trimers by engineering an intra-protomer disulfide linkage in the pre-bridging sheet, I201C-A433C (CC) that locks the gp120 in the receptor non-triggered state. We demonstrated that this disulfide pair prevented CD4 induced-conformational rearrangements in NFL trimers derived from that prototypic subtype A, B and C representatives. Coupling the TD-based design with the engineered disulfide linkage, CC, increased the propensity of Env to form soluble highly stable spike mimetics that are resistant to CD4-induced changes. These advances will allow testing the hypothesis that such stabilized immunogens will more efficiently elicit neutralizing antibodies in small animal models and primates.
IMPORTANCE: HIV-1 displays unprecedented global diversity circulating in the human population. Since the envelope glycoprotein (Env) is the target of neutralizing antibodies, Env-based vaccine candidates that address such diversity are needed. Soluble well-ordered Env mimetics, typified by NFL and SOSIP trimers are attractive vaccine candidates. However, the current designs do not allow most Envs to form well-ordered trimers. Here, we made design modifications to increase the propensity of representatives from two of the major HIV subtypes to form highly stable trimers. This approach should be applicable to other viral Envs, permitting the generation of a repertoire of homogeneous highly stable trimers. The availability of such an array will allow us to assess if sequential or cocktail immune strategies can overcome some of the vaccine challenges presented by HIV diversity.
|Alternate Journal||J. Virol.|
|Grant List||UM1 AI100663 / AI / NIAID NIH HHS / United States|
Structure-guided redesign increases the propensity of HIV Env to generate highly stable soluble trimers.