Stano, A. | Search bioRxiv

bioRxiv2020

Membrane Env liposomes for immunization with HIV spikes

A key goal in HIV vaccine design remains to elicit broadly neutralizing antibodies (bnAbs) against the membrane-embedded envelope glycoprotein spike (mEnv). However, mEnv has lagged behind engineered soluble Envs in vaccine development due to low expression yields and the presence of extraneous proteins on particles. Here, we describe a mEnv vaccine platform that requires no extra proteins or protein engineering. MEnv trimers were fixed, purified and combined with liposomes in mild detergent. On removal of detergent, mEnvs were observed embedded in particles, designated mEnv liposomes (MELs), which were recognized by HIV bnAbs but not non-nAbs. Following sequential immunization in rabbits, MEL antisera neutralized select tier 2 HIV isolates. Variations between the Env immunogens, including a missing N-glycosylation site at position 197 near the CD4 binding site, provide insights into the specificities elicited and possible ways to improve immunogens. MELs can facilitate vaccine design to elicit HIV bnAbs using biochemically defined and multimerized mEnv.

immunology↗

bioRxiv2019

Rational design of hepatitis C virus E2 core nanoparticle vaccines

Hepatitis C virus (HCV) envelope glycoproteins E1 and E2 are critical for cell entry with E2 being the major target of neutralizing antibodies (NAbs). Here, we present a comprehensive strategy for B cell-based HCV vaccine development through E2 optimization and nanoparticle display. We redesigned variable region 2 in a truncated form (tVR2) on E2 cores derived from genotypes 1a and 6a, resulting in improved stability and antigenicity. Crystal structures of three optimized E2 cores with human cross-genotype NAbs (AR3s) revealed how the modified tVR2 stabilizes E2 without altering key neutralizing epitopes. We then displayed these E2 cores on 24- and 60-meric nanoparticles and achieved high yield, high purity, and enhanced antigenicity. In mice, these nanoparticles elicited more effective NAb responses than soluble E2 cores. Next-generation sequencing (NGS) defined distinct B-cell patterns associated with nanoparticle-induced antibody responses, which cross-neutralized HCV by targeting the conserved neutralizing epitopes on E2.\n\nOne Sentence SummaryAn HCV vaccine strategy is presented that displays redesigned E2 cores on nanoparticles as vaccine candidates for eliciting a broadly neutralizing B-cell response.

microbiology↗