A Phase 1 Human Immunodeficiency Virus Vaccine Trial for Cross-Profiling the Kinetics of Serum and Mucosal Antibody Responses to CN54gp140 Modulated by Two Homologous Prime-Boost Vaccine Regimens

A key aspect to finding an efficacious human immunodeficiency virus (HIV) vaccine is the optimization of vaccine schedules that can mediate the efficient maturation of protective immune responses. In the present study, we investigated the effect of alternate booster regimens on the immune responses to a candidate HIV-1 clade C CN54gp140 envelope protein, which was coadministered with the TLR4-agonist glucopyranosyl lipid A-aqueous formulation. Twelve study participants received a common three-dose intramuscular priming series followed by a final booster at either 6 or 12 months. The two homologous prime-boost regimens were well tolerated and induced CN54gp140-specific responses that were observed in both the systemic and mucosal compartments. Levels of vaccine-induced IgG-subclass antibodies correlated significantly with Fc gamma R engagement, and both vaccine regimens were associated with strikingly similar patterns in antibody titer and Fc gamma R-binding profiles. In both groups, identical changes in the antigen (Ag)-specific IgG-subclass fingerprint, leading to a decrease in IgG1 and an increase in IgG4 levels, were modulated by booster injections. Here, the dissection of immune profiles further supports the notion that prime-boost strategies are essential for the induction of diverse Ag-specific HIV-1 responses. The results reported here clearly demonstrate that identical responses were effectively and safely induced by both vaccine regimens, indicating that an accelerated 6-month regimen could be employed for the rapid induction of immune responses against CN54gp140 with no apparent impact on the overall quality of the induced immune response. (This study has been registered at http://ClinicalTrials.gov under registration no.NCT01966900.

Two-component spike nanoparticle vaccine protects macaques from SARS-CoV-2 infection

Brouwer et al. present preclinical evidence in support of a COVID-19 vaccine candidate, designed as a self-assembling two-component protein nanoparticle displaying multiple copies of the SARS-CoV-2 spike protein, which induces strong neutralizing antibody responses and protects from high-dose SARS-CoV-2 challenge.The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is continuing to disrupt personal lives, global healthcare systems, and economies. Hence, there is an urgent need for a vaccine that prevents viral infection, transmission, and disease. Here, we present a two-component protein-based nanoparticle vaccine that displays multiple copies of the SARS-CoV-2 spike protein. Immunization studies show that this vaccine induces potent neutralizing antibody responses in mice, rabbits, and cynomolgus macaques. The vaccine-induced immunity protects macaques against a high-dose challenge, resulting in strongly reduced viral infection and replication i

Development of vaccine platforms for membrane display of surface antigens using HIV-1 Env as model immunogen

The HIV-1 pandemic remains a major public health concern worldwide with over 1.5 million new infections every year. Despite the many effective prevention tools now available, access to treatment and implementations of these tools are proving difficult. Thus, developing an effective vaccine to prevent HIV-1 transmission remains of upmost importance. To date, HIV-1 vaccines failed to induce robust protective immunity and prophylactic vaccines that will elicit long-lasting protective immune responses still remain to be developed. The HIV-1 Envelope glycoprotein (Env) has been the main target of immunogen design with the aim of inducing neutralizing antibodies. In order to cover Env diversity, prophylactic vaccines are expected to induce broadly neutralizing antibodies (bNAbs). This will likely require Env trimers that limit exposure of non-neutralizing antibody (nNAb) epitopes within stabilized closed pre-fusion Envs that exhibit bNAb epitopes. In this thesis, an iterative design process generated membrane-bound Env immunogens that present stabilized native-like trimers. This ultimately resulted in the ConSOSL.UFO.750 trimer that preferentially binds quaternary-specific bNAbs relative to nNAbs. Further characterization of the soluble ConSOSL.UFO.664 confirmed presentation of a closed pre-fusion native-like structure. Immunogenicity studies demonstrated that ConSOSL.UFO.664 can induce autologous Tier 2 neutralization in rabbits and showed that ConSOSL.UFO.750 can modulate the T helper response in a mouse model. To improve the potential of the membrane-bound designs to induce relevant immune responses, virus-like particles (VLPs) based on Mumps and PIV5 pseudotyping were developed. These VLPs displayed Env immunogens and were able to modulate the immune response by intrastructural help in mice. Work presented in this thesis shows the successful design of immunogens that preserve the pre-fusion native-like structure of Env, amenable to various vaccination platforms. The ConSOSL.UFO design has now been moved into phase I clinical trial within the EAVI2020 consortium which will provide critical information for the development of an effective vaccine.Open Acces

MOESM2 of Discrete partitioning of HIV-1 Env forms revealed by viral capture

Additional file 2: Figure S2. Depletion of infectious particles from primary HIV-1 isolates. (A) Depletion of HIV-1 strain Bx08 infectious particles with a panel of Env-specific mAbs. Infectivity depletion was performed as described in Figure 6 legend. Data represent the mean of duplicate experiments. HIV-1 strain CH162.c was analyzed for correlation between (B)  % of p24 capture and  % infectivity depletion, (C)  % of p24 and  % of gp120 capture, and (D)  % gp120 capture and  % infectivity depletion. Spearman correlation coefficients and associated p values are shown. Error bars indicate the standard deviation of 3 or 4 independent experiments

MOESM1 of Discrete partitioning of HIV-1 Env forms revealed by viral capture

Additional file 1: Figure S1. Depletion of infectious particles with a panel of Env-specific mAbs. Infectious stock of HIV-1BaL was treated with the specified antibody, and infectivity depleted as described in Figure 6 legend. Data represent the mean of triplicate experiments

MOESM3 of Discrete partitioning of HIV-1 Env forms revealed by viral capture

Additional file 3: Figure S3. Monoclonal antibodies are completely retained by the magnetic column. Monoclonal antibody b12 was incubated with Protein G magnetic beads in the absence of virus, and passed through a magnetic column. The resulting flow-through was added to HIV-1BaL and titrated on TZM-bl cells to determine if any residual inhibitory activity had passed through the column. Luciferase production was measured after 24 h as a function of viral input

Probing Affinity, Avidity, Anticooperativity, and Competition in Antibody and Receptor Binding to the SARS-CoV-2 Spike by Single Particle Mass Analyses

Determining how antibodies interact with the spike (S) protein of the SARS-CoV-2 virus is critical for combating COVID-19. Structural studies typically employ simplified, truncated constructs that may not fully recapitulate the behavior of the original complexes. Here, we combine two single particle mass analysis techniques (mass photometry and charge-detection mass spectrometry) to enable the measurement of full IgG binding to the trimeric SARS-CoV-2 S ectodomain. Our experiments reveal that antibodies targeting the S-trimer typically prefer stoichiometries lower than the symmetry-predicted 3:1 binding. We determine that this behavior arises from the interplay of steric clashes and avidity effects that are not reflected in common antibody constructs (i.e., Fabs). Surprisingly, these substoichiometric complexes are fully effective at blocking ACE2 binding despite containing free receptor binding sites. Our results highlight the importance of studying antibody/antigen interactions using complete, multimeric constructs and showcase the utility of single particle mass analyses in unraveling these complex interactions

Probing Affinity, Avidity, Anticooperativity, and Competition in Antibody and Receptor Binding to the SARS-CoV-2 Spike by Single Particle Mass Analyses

Determining how antibodies interact with the spike (S) protein of the SARS-CoV-2 virus is critical for combating COVID-19. Structural studies typically employ simplified, truncated constructs that may not fully recapitulate the behavior of the original complexes. Here, we combine two single particle mass analysis techniques (mass photometry and charge-detection mass spectrometry) to enable the measurement of full IgG binding to the trimeric SARS-CoV-2 S ectodomain. Our experiments reveal that antibodies targeting the S-trimer typically prefer stoichiometries lower than the symmetry-predicted 3:1 binding. We determine that this behavior arises from the interplay of steric clashes and avidity effects that are not reflected in common antibody constructs (i.e., Fabs). Surprisingly, these substoichiometric complexes are fully effective at blocking ACE2 binding despite containing free receptor binding sites. Our results highlight the importance of studying antibody/antigen interactions using complete, multimeric constructs and showcase the utility of single particle mass analyses in unraveling these complex interactions