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BACKGROUND: A self-assembling SARS-CoV-2 WA-1 recombinant spike ferritin nanoparticle (SpFN) vaccine co-formulated with Army Liposomal Formulation (ALFQ) adjuvant containing monophosphoryl lipid A and QS-21 (SpFN/ALFQ) has shown protective efficacy in animal challenge models. This trial aims to assess the safety and immunogenicity of SpFN/ALFQ in a first-in-human clinical trial. METHODS: In this phase 1, randomised, double-blind, placebo-controlled, first-in-human clinical trial, adults were randomly assigned (5:5:2) to receive 25 µg or 50 µg of SpFN/ALFQ or saline placebo intramuscularly at day 1 and day 29, with an optional open-label third vaccination at day 181. Enrolment and randomisation occurred sequentially by group; randomisation was done by an interactive web-based randomisation system and only designated unmasked study personnel had access to the randomisation code. Adults were required to be seronegative and unvaccinated for inclusion. Local and systemic reactogenicity, adverse events, binding and neutralising antibodies, and antigen-specific T-cell responses were quantified. For safety analyses, exact 95% Clopper-Pearson CIs for the probability of any incidence of an unsolicited adverse event was computed for each group. For immunogenicity results, CIs for binary variables were computed using the exact Clopper-Pearson methodology, while CIs for geometric mean titres were based on 10 000 empirical bootstrap samples. Post-hoc, paired one-sample t tests were used to assess the increase in mean log-10 neutralising antibody titres between day 29 and day 43 (after the second vaccination) for the primary SARS-CoV-2 targets of interest. This trial is registered at ClinicalTrials.gov, NCT04784767, and is closed to new participants. FINDINGS: Between April 7, and June 29, 2021, 29 participants were enrolled in the study. 20 individuals were assigned to receive 25 µg SpFN/ALFQ, four to 50 µg SpFN/ALFQ, and five to placebo. Neutralising antibody responses peaked at day 43, 2 weeks after the second dose. Neutralisation activity against multiple omicron subvariants decayed more slowly than against the D614G or beta variants until 5 months after second vaccination for both dose groups. CD4+ T-cell responses were elicited 4 weeks after the first dose and were boosted after a second dose of SpFN/ALFQ for both dose groups. Neutralising antibody titres against early omicron subvariants and clade 1 sarbecoviruses were detectable after two immunisations and peaked after the third immunisation for both dose groups. Neutralising antibody titres against XBB.1.5 were detected after three vaccinations. Passive IgG transfer from vaccinated volunteers into Syrian golden hamsters controlled replication of SARS-CoV-1 after challenge. INTERPRETATION: SpFN/ALFQ was well tolerated and elicited robust and durable binding antibody and neutralising antibody titres against a broad panel of SARS-CoV-2 variants and other sarbecoviruses. FUNDING: US Department of Defense, Defense Health Agency.
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Vacunas contra la COVID-19 , COVID-19 , Ferritinas , Lípido A , Liposomas , Nanopartículas , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Humanos , Vacunas contra la COVID-19/inmunología , Vacunas contra la COVID-19/administración & dosificación , Vacunas contra la COVID-19/efectos adversos , Método Doble Ciego , Adulto , Masculino , Femenino , COVID-19/prevención & control , COVID-19/inmunología , SARS-CoV-2/inmunología , Nanopartículas/administración & dosificación , Lípido A/análogos & derivados , Lípido A/administración & dosificación , Lípido A/farmacología , Lípido A/inmunología , Liposomas/administración & dosificación , Glicoproteína de la Espiga del Coronavirus/inmunología , Saponinas/administración & dosificación , Saponinas/inmunología , Saponinas/farmacología , Saponinas/efectos adversos , Anticuerpos Antivirales/sangre , Persona de Mediana Edad , Adyuvantes Inmunológicos/administración & dosificación , Adyuvantes Inmunológicos/farmacología , Adyuvantes de Vacunas/administración & dosificación , Anticuerpos Neutralizantes/sangre , Adulto Joven , NanovacunasRESUMEN
An effective HIV-1 vaccine must elicit broadly neutralizing antibodies (bnAbs) against highly diverse Envelope glycoproteins (Env). Since Env with the longest hypervariable (HV) loops is more resistant to the cognate bnAbs than Env with shorter HV loops, we redesigned hypervariable loops for updated Env consensus sequences of subtypes B and C and CRF01_AE. Using modeling with AlphaFold2, we reduced the length of V1, V2, and V5 HV loops while maintaining the integrity of the Env structure and glycan shield, and modified the V4 HV loop. Spacers are designed to limit strain-specific targeting. All updated Env are infectious as pseudoviruses. Preliminary structural characterization suggests that the modified HV loops have a limited impact on Env's conformation. Binding assays show improved binding to modified subtype B and CRF01_AE Env but not to subtype C Env. Neutralization assays show increases in sensitivity to bnAbs, although not always consistently across clades. Strikingly, the HV loop modification renders the resistant CRF01_AE Env sensitive to 10-1074 despite the absence of a glycan at N332.
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Anticuerpos Neutralizantes , Anticuerpos Anti-VIH , VIH-1 , Productos del Gen env del Virus de la Inmunodeficiencia Humana , VIH-1/inmunología , Humanos , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Productos del Gen env del Virus de la Inmunodeficiencia Humana/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/metabolismo , Anticuerpos Anti-VIH/inmunología , Anticuerpos Neutralizantes/inmunología , Vacunas contra el SIDA/inmunología , Pruebas de Neutralización , Células HEK293 , Secuencia de Consenso , Infecciones por VIH/virología , Infecciones por VIH/inmunología , Unión Proteica , Epítopos/inmunologíaRESUMEN
Given the continuous emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VoCs), immunotherapeutics that target conserved epitopes on the spike (S) glycoprotein have therapeutic advantages. Here, we report the crystal structure of the SARS-CoV-2 S receptor-binding domain (RBD) at 1.95 Å and describe flexibility and distinct conformations of the angiotensin-converting enzyme 2 (ACE2)-binding site. We identify a set of SARS-CoV-2-reactive monoclonal antibodies (mAbs) with broad RBD cross-reactivity including SARS-CoV-2 Omicron subvariants, SARS-CoV-1, and other sarbecoviruses and determine the crystal structures of mAb-RBD complexes with Ab246 and CR3022 mAbs targeting the class IV site, WRAIR-2134, which binds the recently designated class V epitope, and WRAIR-2123, the class I ACE2-binding site. The broad reactivity of class IV and V mAbs to conserved regions of SARS-CoV-2 VoCs and other sarbecovirus provides a framework for long-term immunotherapeutic development strategies.
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COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/metabolismo , Enzima Convertidora de Angiotensina 2/metabolismo , Anticuerpos Neutralizantes/química , Anticuerpos Antivirales/química , Sitios de Unión , EpítoposRESUMEN
Zika virus (ZIKV) is an emerging pathogen that causes devastating congenital defects. The overlapping epidemiology and immunologic cross-reactivity between ZIKV and dengue virus (DENV) pose complex challenges to vaccine design, given the potential for antibody-dependent enhancement of disease. Therefore, classification of ZIKV-specific antibody targets is of notable value. From a ZIKV-infected rhesus macaque, we identify ZIKV-reactive B cells and isolate potent neutralizing monoclonal antibodies (mAbs) with no cross-reactivity to DENV. We group these mAbs into four distinct antigenic groups targeting ZIKV-specific cross-protomer epitopes on the envelope glycoprotein. Co-crystal structures of representative mAbs in complex with ZIKV envelope glycoprotein reveal envelope-dimer epitope and unique dimer-dimer epitope targeting. All four specificities are serologically identified in convalescent humans following ZIKV infection, and representative mAbs from all four groups protect against ZIKV replication in mice. These results provide key insights into ZIKV-specific antigenicity and have implications for ZIKV vaccine, diagnostic, and therapeutic development.
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Virus del Dengue , Dengue , Vacunas Virales , Infección por el Virus Zika , Virus Zika , Humanos , Animales , Ratones , Anticuerpos Neutralizantes , Epítopos , Macaca mulatta , Anticuerpos Antivirales , Anticuerpos Monoclonales , Vacunas Virales/uso terapéutico , Proteínas del Envoltorio Viral/químicaRESUMEN
Novel therapeutic monoclonal antibodies (MAbs) must accommodate comprehensive breadth of activity against diverse sarbecoviruses and high neutralization potency to overcome emerging variants. Here, we report the crystal structure of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain (RBD) in complex with MAb WRAIR-2063, a moderate-potency neutralizing antibody with exceptional sarbecovirus breadth, that targets the highly conserved cryptic class V epitope. This epitope overlaps substantially with the spike protein N-terminal domain (NTD) -interacting region and is exposed only when the spike is in the open conformation, with one or more RBDs accessible. WRAIR-2063 binds the RBD of SARS-CoV-2 WA-1, all variants of concern (VoCs), and clade 1 to 4 sarbecoviruses with high affinity, demonstrating the conservation of this epitope and potential resiliency against variation. We compare structural features of additional class V antibodies with their reported neutralization capacity to further explore the utility of the class V epitope as a pan-sarbecovirus vaccine and therapeutic target. IMPORTANCE Characterization of MAbs against SARS-CoV-2, elicited through vaccination or natural infection, has provided vital immunotherapeutic options for curbing the COVID-19 pandemic and has supplied critical insights into SARS-CoV-2 escape, transmissibility, and mechanisms of viral inactivation. Neutralizing MAbs that target the RBD but do not block ACE2 binding are of particular interest because the epitopes are well conserved within sarbecoviruses and MAbs targeting this area demonstrate cross-reactivity. The class V RBD-targeted MAbs localize to an invariant site of vulnerability, provide a range of neutralization potency, and exhibit considerable breadth against divergent sarbecoviruses, with implications for vaccine and therapeutic development.
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Anticuerpos Antivirales , COVID-19 , Epítopos , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo , Humanos , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/metabolismo , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/química , Anticuerpos Antivirales/metabolismo , Epítopos/química , SARS-CoV-2/química , SARS-CoV-2/metabolismo , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/química , Dominios Proteicos , Cristalografía por Rayos X , Estructura Cuaternaria de Proteína , Modelos Moleculares , Línea CelularRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines demonstrate reduced protection against acquisition of BA.5 subvariant but are still effective against severe disease. However, immune correlates of protection against BA.5 remain unknown. We report the immunogenicity and protective efficacy of vaccine regimens consisting of the vector-based Ad26.COV2.S vaccine and the adjuvanted spike ferritin nanoparticle (SpFN) vaccine against a high-dose, mismatched Omicron BA.5 challenge in macaques. The SpFNx3 and Ad26 + SpFNx2 regimens elicit higher antibody responses than Ad26x3, whereas the Ad26 + SpFNx2 and Ad26x3 regimens induce higher CD8 T cell responses than SpFNx3. The Ad26 + SpFNx2 regimen elicits the highest CD4 T cell responses. All three regimens suppress peak and day 4 viral loads in the respiratory tract, which correlate with both humoral and cellular immune responses. This study demonstrates that both homologous and heterologous regimens involving Ad26.COV2.S and SpFN vaccines provide robust protection against a mismatched BA.5 challenge in macaques.
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COVID-19 , Nanopartículas , Vacunas , Humanos , Animales , Macaca , Ad26COVS1 , COVID-19/prevención & control , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , FerritinasRESUMEN
This study demonstrates the impact of adjuvant on the development of T follicular helper (Tfh) and B cells, and their influence on antibody responses in mice vaccinated with SARS-CoV-2-spike-ferritin-nanoparticle (SpFN) adjuvanted with either Army Liposome Formulation containing QS-21 (SpFN + ALFQ) or Alhydrogel® (SpFN + AH). SpFN + ALFQ increased the size and frequency of germinal center (GC) B cells in the vaccine-draining lymph nodes and increased the frequency of antigen-specific naive B cells. A single vaccination with SpFN + ALFQ resulted in a higher frequency of IL-21-producing-spike-specific Tfh and GC B cells in the draining lymph nodes and spleen, S-2P protein-specific IgM and IgG antibodies, and elicitation of robust cross-neutralizing antibodies against SARS-CoV-2 variants as early as day 7, which was enhanced by a second vaccination. This was associated with the generation of high titer, high avidity binding antibodies. The third vaccination with SpFN + ALFQ elicited high levels of neutralizing antibodies against the Omicron variant. No cross-neutralizing antibodies against Omicron were induced with SpFN + AH. These findings highlight the importance of ALFQ in orchestrating early induction of antigen-specific Tfh and GC B cell responses and long-lived plasma cells in the bone marrow. The early engagement of S-2P specific naive B cells and high titer IgM antibodies shape the development of long-term neutralization breadth.
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Despite rapid and ongoing vaccine and therapeutic development, SARS-CoV-2 continues to evolve and evade, presenting a need for next-generation diverse therapeutic modalities. Here we show that nurse sharks immunized with SARS-CoV-2 recombinant receptor binding domain (RBD), RBD-ferritin (RFN), or spike protein ferritin nanoparticle (SpFN) immunogens elicit a set of new antigen receptor antibody (IgNAR) molecules that target two non-overlapping conserved epitopes on the spike RBD. Representative shark antibody variable NAR-Fc chimeras (ShAbs) targeting either of the two epitopes mediate cell-effector functions, with high affinity to all SARS-CoV-2 viral variants of concern, including the divergent Omicron strains. The ShAbs potently cross-neutralize SARS-CoV-2 WA-1, Alpha, Beta, Delta, Omicron BA.1 and BA.5, and SARS-CoV-1 pseudoviruses, and confer protection against SARS-CoV-2 challenge in the K18-hACE2 transgenic mouse model. Structural definition of the RBD-ShAb01-ShAb02 complex enabled design and production of multi-specific nanobodies with enhanced neutralization capacity, and picomolar affinity to divergent sarbecovirus clade 1a, 1b and 2 RBD molecules. These shark nanobodies represent potent immunotherapeutics both for current use, and future sarbecovirus pandemic preparation.
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COVID-19 , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo , Anticuerpos de Dominio Único , Animales , Ratones , Anticuerpos Neutralizantes , Anticuerpos Antivirales , COVID-19/prevención & control , Epítopos , Ferritinas/genética , Fragmentos Fc de Inmunoglobulinas , Ratones Transgénicos , SARS-CoV-2/genética , Glicoproteína de la Espiga del Coronavirus/genética , TiburonesRESUMEN
Developing a preventative vaccine for HIV-1 has been a global priority. The elicitation of broadly neutralizing antibodies (bNAbs) against a broad range of HIV-1 envelopes (Envs) from various strains appears to be a critical requirement for an efficacious HIV-1 vaccine. To understand their ability to neutralize HIV-1, it is important to characterize the binding characteristics of bNAbs. Our work is the first to utilize microscale thermophoresis (MST), a rapid, economical, and flexible in-solution temperature gradient method to quantitatively determine the binding affinities of bNAbs and non-neutralizing monoclonal antibodies (mAbs) to HIV-1 recombinant envelope monomer and trimer proteins of different subtypes, pseudoviruses (PVs), infectious molecular clones (IMCs), and cells expressing the trimer. Our results demonstrate that the binding affinities were subtype-dependent. The bNAbs exhibited a higher affinity to IMCs compared to PVs and recombinant proteins. The bNAbs and mAbs bound with high affinity to native-like gp160 trimers expressed on the surface of CEM cells compared to soluble recombinant proteins. Interesting differences were seen with V2-specific mAbs. Although they recognize linear epitopes, one of the antibodies also bound to the Envs on PVs, IMCs, and a recombinant trimer protein, suggesting that the epitope was not occluded. The identification of epitopes on the envelope surface that can bind to high affinity mAbs could be useful for designing HIV-1 vaccines and for down-selecting vaccine candidates that can induce high affinity antibodies to the HIV-1 envelope in their native conformation.
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Vacunas contra el SIDA , Enfermedades Transmisibles , Seropositividad para VIH , VIH-1 , Humanos , Anticuerpos ampliamente neutralizantes , Anticuerpos Monoclonales , Células Clonales , Epítopos , Proteínas Recombinantes , Glicoproteínas , Proteínas gp160 de Envoltorio del VIHRESUMEN
Emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and waning immunity call for next-generation vaccine strategies. Here, we assessed the immunogenicity and protective efficacy of two SARS-CoV-2 vaccines targeting the WA1/2020 spike protein, Ad26.COV2.S (Ad26) and Spike ferritin Nanoparticle (SpFN), in nonhuman primates, delivered as either a homologous (SpFN/SpFN and Ad26/Ad26) or heterologous (Ad26/SpFN) prime-boost regimen. The Ad26/SpFN regimen elicited the highest CD4 T cell and memory B cell responses, the SpFN/SpFN regimen generated the highest binding and neutralizing antibody responses, and the Ad26/Ad26 regimen generated the most robust CD8 T cell responses. Despite these differences, protective efficacy against SARS-CoV-2 Omicron BA.1 challenge was similar for all three regimens. After challenge, all vaccinated monkeys showed significantly reduced peak and day 4 viral loads in both bronchoalveolar lavage and nasal swabs as compared with sham animals. The efficacy conferred by these three immunologically distinct vaccine regimens suggests that both humoral and cellular immunity contribute to protection against SARS-CoV-2 Omicron challenge.
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Epstein-Barr virus (EBV) is nearly ubiquitous in adults. EBV causes infectious mononucleosis and is associated with B cell lymphomas, epithelial cell malignancies, and multiple sclerosis. The EBV gH/gL glycoprotein complex facilitates fusion of virus membrane with host cells and is a target of neutralizing antibodies. Here, we examined the sites of vulnerability for virus neutralization and fusion inhibition within EBV gH/gL. We developed a panel of human monoclonal antibodies (mAbs) that targeted five distinct antigenic sites on EBV gH/gL and prevented infection of epithelial and B cells. Structural analyses using X-ray crystallography and electron microscopy revealed multiple sites of vulnerability and defined the antigenic landscape of EBV gH/gL. One mAb provided near-complete protection against viremia and lymphoma in a humanized mouse EBV challenge model. Our findings provide structural and antigenic knowledge of the viral fusion machinery, yield a potential therapeutic antibody to prevent EBV disease, and emphasize gH/gL as a target for herpesvirus vaccines and therapeutics.
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Infecciones por Virus de Epstein-Barr , Herpesvirus Humano 4 , Cricetinae , Ratones , Animales , Humanos , Proteínas del Envoltorio Viral , Cricetulus , Glicoproteínas de Membrana , Células CHORESUMEN
The COVID-19 pandemic has had a staggering impact on social, economic, and public health systems worldwide. Vaccine development and mobilization against SARS-CoV-2 (the etiologic agent of COVID-19) has been rapid. However, novel strategies are still necessary to slow the pandemic, and this includes new approaches to vaccine development and/or delivery that will improve vaccination compliance and demonstrate efficacy against emerging variants. Here, we report on the immunogenicity and efficacy of a SARS-CoV-2 vaccine comprising stabilized, pre-fusion spike protein trimers displayed on a ferritin nanoparticle (SpFN) adjuvanted with either conventional aluminum hydroxide or the Army Liposomal Formulation QS-21 (ALFQ) in a cynomolgus macaque COVID-19 model. Vaccination resulted in robust cell-mediated and humoral responses and a significant reduction in lung lesions following SARS-CoV-2 infection. The strength of the immune response suggests that dose sparing through reduced or single dosing in primates may be possible with this vaccine. Overall, the data support further evaluation of SpFN as a SARS-CoV-2 protein-based vaccine candidate with attention to fractional dosing and schedule optimization.
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The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants stresses the continued need for next-generation vaccines that confer broad protection against coronavirus disease 2019 (COVID-19). We developed and evaluated an adjuvanted SARS-CoV-2 spike ferritin nanoparticle (SpFN) vaccine in nonhuman primates. High-dose (50 µg) SpFN vaccine, given twice 28 days apart, induced a Th1-biased CD4 T cell helper response and elicited neutralizing antibodies against SARS-CoV-2 wild-type and variants of concern, as well as against SARS-CoV-1. These potent humoral and cell-mediated immune responses translated into rapid elimination of replicating virus in the upper and lower airways and lung parenchyma of nonhuman primates following high-dose SARS-CoV-2 respiratory challenge. The immune response elicited by SpFN vaccination and resulting efficacy in nonhuman primates supports the utility of SpFN as a vaccine candidate for SARS-causing betacoronaviruses.
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COVID-19 , Nanopartículas , Animales , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacunas contra la COVID-19 , Ferritinas , Humanos , Inmunidad , Macaca mulatta , SARS-CoV-2 , Glicoproteína de la Espiga del CoronavirusRESUMEN
The emergence of novel potentially pandemic pathogens necessitates the rapid manufacture and deployment of effective, stable, and locally manufacturable vaccines on a global scale. In this study, the ability of the Escherichia coli expression system to produce the receptor binding domain (RBD) of the SARS-CoV-2 spike protein was evaluated. The RBD of the original Wuhan-Hu1 variant and of the Alpha and Beta variants of concern (VoC) were expressed in E. coli, and their biochemical and immunological profiles were compared to RBD produced in mammalian cells. The E. coli-produced RBD variants recapitulated the structural character of mammalian-expressed RBD and bound to human angiotensin converting enzyme (ACE2) receptor and a panel of neutralizing SARS-CoV-2 monoclonal antibodies. A pilot vaccination in mice with bacterial RBDs formulated with a novel liposomal adjuvant, Army Liposomal Formulation containing QS21 (ALFQ), induced polyclonal antibodies that inhibited RBD association to ACE2 in vitro and potently neutralized homologous and heterologous SARS-CoV-2 pseudoviruses. Although all vaccines induced neutralization of the non-vaccine Delta variant, only the Beta RBD vaccine produced in E. coli and mammalian cells effectively neutralized the Omicron BA.1 pseudovirus. These outcomes warrant further exploration of E. coli as an expression platform for non-glycosylated, soluble immunogens for future rapid response to emerging pandemic pathogens.
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The emergence of variants of concern, some with reduced susceptibility to COVID-19 vaccines underscores consideration for the understanding of vaccine design that optimizes induction of effective cellular and humoral immune responses. We assessed a SARS-CoV-2 spike-ferritin nanoparticle (SpFN) immunogen paired with two distinct adjuvants, Alhydrogel® or Army Liposome Formulation containing QS-21 (ALFQ) for unique vaccine evoked immune signatures. Recruitment of highly activated multifaceted antigen-presenting cells to the lymph nodes of SpFN+ALFQ vaccinated mice was associated with an increased frequency of polyfunctional spike-specific memory CD4+ T cells and Kb spike-(539-546)-specific long-lived memory CD8+ T cells with effective cytolytic function and distribution to the lungs. The presence of this epitope in SARS-CoV, suggests that generation of cross-reactive T cells may be induced against other coronavirus strains. Our study reveals that a nanoparticle vaccine, combined with a potent adjuvant that effectively engages innate immune cells, enhances SARS-CoV-2-specific durable adaptive immune T cell responses.
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The need for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) next-generation vaccines has been highlighted by the rise of variants of concern (VoCs) and the long-term threat of emerging coronaviruses. Here, we design and characterize four categories of engineered nanoparticle immunogens that recapitulate the structural and antigenic properties of the prefusion SARS-CoV-2 spike (S), S1, and receptor-binding domain (RBD). These immunogens induce robust S binding, ACE2 inhibition, and authentic and pseudovirus neutralizing antibodies against SARS-CoV-2. A spike-ferritin nanoparticle (SpFN) vaccine elicits neutralizing titers (ID50 > 10,000) following a single immunization, whereas RBD-ferritin nanoparticle (RFN) immunogens elicit similar responses after two immunizations and also show durable and potent neutralization against circulating VoCs. Passive transfer of immunoglobulin G (IgG) purified from SpFN- or RFN-immunized mice protects K18-hACE2 transgenic mice from a lethal SARS-CoV-2 challenge. Furthermore, S-domain nanoparticle immunization elicits ACE2-blocking activity and ID50 neutralizing antibody titers >2,000 against SARS-CoV-1, highlighting the broad response elicited by these immunogens.
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Prevention of viral escape and increased coverage against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern require therapeutic monoclonal antibodies (mAbs) targeting multiple sites of vulnerability on the coronavirus spike glycoprotein. Here we identify several potent neutralizing antibodies directed against either the N-terminal domain (NTD) or the receptor-binding domain (RBD) of the spike protein. Administered in combinations, these mAbs provided low-dose protection against SARS-CoV-2 infection in the K18-human angiotensin-converting enzyme 2 mouse model, using both neutralization and Fc effector antibody functions. The RBD mAb WRAIR-2125, which targets residue F486 through a unique heavy-chain and light-chain pairing, demonstrated potent neutralizing activity against all major SARS-CoV-2 variants of concern. In combination with NTD and other RBD mAbs, WRAIR-2125 also prevented viral escape. These data demonstrate that NTD/RBD mAb combinations confer potent protection, likely leveraging complementary mechanisms of viral inactivation and clearance.
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Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , COVID-19/inmunología , SARS-CoV-2/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/metabolismo , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/inmunología , Anticuerpos Antivirales/metabolismo , Sitios de Unión/genética , COVID-19/metabolismo , COVID-19/prevención & control , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Mapeo Epitopo , Epítopos/química , Epítopos/inmunología , Epítopos/metabolismo , Humanos , Ratones Transgénicos , Pruebas de Neutralización , Unión Proteica , Conformación Proteica , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , Homología de Secuencia de Aminoácido , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/metabolismo , Análisis de SupervivenciaRESUMEN
Human metapneumovirus (HMPV) is a major cause of respiratory disease worldwide, particularly among children and the elderly. Although there is no licensed HMPV vaccine, promising candidates have been identified for related pneumoviruses based on the structure-based stabilization of the fusion (F) glycoprotein trimer, with prefusion-stabilized F glycoprotein trimers eliciting significantly higher neutralizing responses than their postfusion F counterparts. However, immunization with HMPV F trimers in either prefusion or postfusion conformations has been reported to elicit equivalent neutralization responses. Here we investigate the impact of stabilizing disulfides, especially interprotomer disulfides (IP-DSs) linking protomers of the F trimer, on the elicitation of HMPV-neutralizing responses. We designed F trimer disulfides, screened for their expression, and used electron microscopy (EM) to confirm their formation, including that of an unexpected postfusion variant. In mice, IP-DS-stabilized prefusion and postfusion HMPV F elicited significantly higher neutralizing responses than non-IP-DS-stabilized HMPV Fs. In macaques, the impact of IP-DS stabilization was more measured, although IP-DS-stabilized variants of either prefusion or postfusion HMPV F induced neutralizing responses many times the average titers observed in a healthy human cohort. Serological and absorption-based analyses of macaque responses revealed elicited HMPV-neutralizing responses to be absorbed differently by IP-DS-containing and by non-IP-DS-containing postfusion Fs, suggesting IP-DS stabilization to alter not only the immunogenicity of select epitopes but their antigenicity as well. We speculate the observed increase in immunogenicity by IP-DS trimers to be related to reduced interprotomer flexibility within the HMPV F trimer.
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Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Disulfuros/química , Epítopos/inmunología , Glicoproteínas/inmunología , Metapneumovirus/inmunología , Mutación , Animales , Glicoproteínas/genética , Humanos , Inmunización , Macaca , Metapneumovirus/genética , Ratones , Regiones Promotoras GenéticasRESUMEN
Emergence of novel variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) underscores the need for next-generation vaccines able to elicit broad and durable immunity. Here we report the evaluation of a ferritin nanoparticle vaccine displaying the receptor-binding domain of the SARS-CoV-2 spike protein (RFN) adjuvanted with Army Liposomal Formulation QS-21 (ALFQ). RFN vaccination of macaques using a two-dose regimen resulted in robust, predominantly Th1 CD4+ T cell responses and reciprocal peak mean serum neutralizing antibody titers of 14,000 to 21,000. Rapid control of viral replication was achieved in the upper and lower airways of animals after high-dose SARS-CoV-2 respiratory challenge, with undetectable replication within 4 d in seven of eight animals receiving 50 µg of RFN. Cross-neutralization activity against SARS-CoV-2 variant B.1.351 decreased only approximately twofold relative to WA1/2020. In addition, neutralizing, effector antibody and cellular responses targeted the heterotypic SARS-CoV-1, highlighting the broad immunogenicity of RFN-ALFQ for SARS-CoV-like Sarbecovirus vaccine development.
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Vacunas contra la COVID-19/administración & dosificación , COVID-19/virología , Macaca mulatta/inmunología , Nanopartículas/química , Receptores Virales/metabolismo , SARS-CoV-2/inmunología , Adyuvantes Inmunológicos/administración & dosificación , Animales , Anticuerpos Neutralizantes/biosíntesis , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/biosíntesis , Anticuerpos Antivirales/inmunología , COVID-19/prevención & control , Vacunas contra la COVID-19/inmunología , Ferritinas/química , SARS-CoV-2/metabolismo , Linfocitos T/inmunologíaRESUMEN
A primary goal of HIV-1 vaccine development is the consistent elicitation of protective, neutralizing antibodies. While highly similar neutralizing antibodies (nAbs) have been isolated from multiple HIV-infected individuals, it is unclear whether vaccination can consistently elicit highly similar nAbs in genetically diverse primates. Here, we show in three outbred rhesus macaques that immunization with Env elicits a genotypically and phenotypically conserved nAb response. From these vaccinated macaques, we isolated four antibody lineages that had commonalities in immunoglobulin variable, diversity, and joining gene segment usage. Atomic-level structures of the antigen binding fragments of the two most similar antibodies showed nearly identical paratopes. The Env binding modes of each of the four vaccine-induced nAbs were distinct from previously known monoclonal HIV-1 neutralizing antibodies, but were nearly identical to each other. The similarities of these antibodies show that the immune system in outbred primates can respond to HIV-1 Env vaccination with a similar structural and genotypic solution for recognizing a particular neutralizing epitope. These results support rational vaccine design for HIV-1 that aims to reproducibly elicit, in genetically diverse primates, nAbs with specific paratope structures capable of binding conserved epitopes.