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mRNA-1273 vaccine efficacy against SARS-CoV-2 Delta wanes over time; however, there are limited data on the impact of durability of immune responses on protection. Here, we immunized rhesus macaques and assessed immune responses over 1 year in blood and upper and lower airways. Serum neutralizing titers to Delta were 280 and 34 reciprocal ID50 at weeks 6 (peak) and 48 (challenge), respectively. Antibody-binding titers also decreased in bronchoalveolar lavage (BAL). Four days after Delta challenge, the virus was unculturable in BAL, and subgenomic RNA declined by â¼3-log10 compared with control animals. In nasal swabs, sgRNA was reduced by 1-log10, and the virus remained culturable. Anamnestic antibodies (590-fold increased titer) but not T cell responses were detected in BAL by day 4 post-challenge. mRNA-1273-mediated protection in the lungs is durable but delayed and potentially dependent on anamnestic antibody responses. Rapid and sustained protection in upper and lower airways may eventually require a boost.
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SARS-CoV-2 Omicron is highly transmissible and has substantial resistance to neutralization following immunization with ancestral spike-matched vaccines. It is unclear whether boosting with Omicron-matched vaccines would enhance protection. Here, nonhuman primates that received mRNA-1273 at weeks 0 and 4 were boosted at week 41 with mRNA-1273 or mRNA-Omicron. Neutralizing titers against D614G were 4,760 and 270 reciprocal ID50 at week 6 (peak) and week 41 (preboost), respectively, and 320 and 110 for Omicron. 2 weeks after the boost, titers against D614G and Omicron increased to 5,360 and 2,980 for mRNA-1273 boost and 2,670 and 1,930 for mRNA-Omicron, respectively. Similar increases against BA.2 were observed. Following either boost, 70%-80% of spike-specific B cells were cross-reactive against WA1 and Omicron. Equivalent control of virus replication in lower airways was observed following Omicron challenge 1 month after either boost. These data show that mRNA-1273 and mRNA-Omicron elicit comparable immunity and protection shortly after the boost.
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COVID-19 , SARS-CoV-2 , Vacuna nCoV-2019 mRNA-1273 , Animales , Anticuerpos Neutralizantes , Anticuerpos Antivirales , COVID-19/prevención & control , Macaca , ARN MensajeroRESUMEN
A mucosal route of vaccination could prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication at the site of infection and limit transmission. We compared protection against heterologous XBB.1.16 challenge in nonhuman primates (NHPs) ~5 months following intramuscular boosting with bivalent mRNA encoding WA1 and BA.5 spike proteins or mucosal boosting with a WA1-BA.5 bivalent chimpanzee adenoviral-vectored vaccine delivered by intranasal or aerosol device. NHPs boosted by either mucosal route had minimal virus replication in the nose and lungs, respectively. By contrast, protection by intramuscular mRNA was limited to the lower airways. The mucosally delivered vaccine elicited durable airway IgG and IgA responses and, unlike the intramuscular mRNA vaccine, induced spike-specific B cells in the lungs. IgG, IgA and T cell responses correlated with protection in the lungs, whereas mucosal IgA alone correlated with upper airway protection. This study highlights differential mucosal and serum correlates of protection and how mucosal vaccines can durably prevent infection against SARS-CoV-2.
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The vaccine-mediated elicitation of antibodies (Abs) capable of neutralizing diverse HIV-1 strains has been a long-standing goal. To understand how broadly neutralizing antibodies (bNAbs) can be elicited, we identified, characterized, and tracked five neutralizing Ab lineages targeting the HIV-1-fusion peptide (FP) in vaccinated macaques over time. Genetic and structural analyses revealed two of these lineages to belong to a reproducible class capable of neutralizing up to 59% of 208 diverse viral strains. B cell analysis indicated each of the five lineages to have been initiated and expanded by FP-carrier priming, with envelope (Env)-trimer boosts inducing cross-reactive neutralization. These Abs had binding-energy hotspots focused on FP, whereas several FP-directed Abs induced by immunization with Env trimer-only were less FP-focused and less broadly neutralizing. Priming with a conserved subregion, such as FP, can thus induce Abs with binding-energy hotspots coincident with the target subregion and capable of broad neutralization.
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Vacunas contra el SIDA/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Anti-VIH/inmunología , Péptidos/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/clasificación , Linfocitos B/citología , Linfocitos B/metabolismo , Cristalografía por Rayos X , Femenino , Células HEK293 , Anticuerpos Anti-VIH/química , Anticuerpos Anti-VIH/clasificación , VIH-1/metabolismo , Humanos , Macaca mulatta , Masculino , Péptidos/química , Estructura Terciaria de Proteína , Productos del Gen env del Virus de la Inmunodeficiencia Humana/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Productos del Gen env del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
The design of immunogens that elicit broadly reactive neutralizing antibodies (bnAbs) has been a major obstacle to HIV-1 vaccine development. One approach to assess potential immunogens is to use mice expressing precursors of human bnAbs as vaccination models. The bnAbs of the VRC01-class derive from the IGHV1-2 immunoglobulin heavy chain and neutralize a wide spectrum of HIV-1 strains via targeting the CD4 binding site of the envelope glycoprotein gp120. We now describe a mouse vaccination model that allows a germline human IGHV1-2(∗)02 segment to undergo normal V(D)J recombination and, thereby, leads to the generation of peripheral B cells that express a highly diverse repertoire of VRC01-related receptors. When sequentially immunized with modified gp120 glycoproteins designed to engage VRC01 germline and intermediate antibodies, IGHV1-2(∗)02-rearranging mice, which also express a VRC01-antibody precursor light chain, can support the affinity maturation of VRC01 precursor antibodies into HIV-neutralizing antibody lineages.
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Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , VIH-1/inmunología , Inmunización , Cadenas Pesadas de Inmunoglobulina/inmunología , Células Precursoras de Linfocitos B/inmunología , Animales , Anticuerpos Monoclonales/genética , Linfocitos B/inmunología , Anticuerpos ampliamente neutralizantes , Línea Celular , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/inmunología , Anticuerpos Anti-VIH , Cadenas Pesadas de Inmunoglobulina/química , Cadenas Pesadas de Inmunoglobulina/genética , Concentración 50 Inhibidora , Ratones , Eliminación de Secuencia , Linfocitos T/inmunologíaRESUMEN
Vaccine elicitation of broadly neutralizing antibodies (bnAbs) is a key HIV-research goal. The VRC01 class of bnAbs targets the CD4-binding site on the HIV-envelope trimer and requires extensive somatic hypermutation (SHM) to neutralize effectively. Despite substantial progress, vaccine-induced VRC01-class antibodies starting from unmutated precursors have exhibited limited neutralization breadth, particularly against viruses bearing glycan on loop D residue N276 (glycan276), present on most circulating strains. Here, using sequential immunization of immunoglobulin (Ig)-humanized mice expressing diverse unmutated VRC01-class antibody precursors, we elicited serum responses capable of neutralizing viruses bearing glycan276 and isolated multiple lineages of VRC01-class bnAbs, including two with >50% breadth on a 208-strain panel. Crystal structures of representative bnAbs revealed the same mode of recognition as known VRC01-class bnAbs. Structure-function studies further pinpointed key mutations and correlated their induction with specific immunizations. VRC01-class bnAbs can thus be matured by sequential immunization from unmutated ancestors to >50% breadth, and we delineate immunogens and regimens inducing key SHM.
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Vacunas contra el SIDA/inmunología , Linfocitos B/inmunología , Anticuerpos ampliamente neutralizantes/metabolismo , Anticuerpos Anti-VIH/metabolismo , Infecciones por VIH/inmunología , VIH-1/fisiología , Mutación/genética , Animales , Anticuerpos ampliamente neutralizantes/genética , Modelos Animales de Enfermedad , Células HEK293 , Anticuerpos Anti-VIH/genética , Humanos , Activación de Linfocitos , Ratones , Ratones Transgénicos , Hipermutación Somática de Inmunoglobulina , VacunaciónRESUMEN
An effective vaccine for respiratory syncytial virus (RSV) is an unrealized public health goal. A single dose of the prefusion-stabilized fusion (F) glycoprotein subunit vaccine (DS-Cav1) substantially increases serum-neutralizing activity in healthy adults. We sought to determine whether DS-Cav1 vaccination induces a repertoire mirroring the pre-existing diversity from natural infection or whether antibody lineages targeting specific epitopes predominate. We evaluated RSV F-specific B cell responses before and after vaccination in six participants using complementary B cell sequencing methodologies and identified 555 clonal lineages. DS-Cav1-induced lineages recognized the prefusion conformation of F (pre-F) and were genetically diverse. Expressed antibodies recognized all six antigenic sites on the pre-F trimer. We identified 34 public clonotypes, and structural analysis of two antibodies from a predominant clonotype revealed a common mode of recognition. Thus, vaccination with DS-Cav1 generates a diverse polyclonal response targeting the antigenic sites on pre-F, supporting the development and advanced testing of pre-F-based vaccines against RSV.
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Anticuerpos Antivirales/inmunología , Formación de Anticuerpos/inmunología , Infecciones por Virus Sincitial Respiratorio/inmunología , Vacunas contra Virus Sincitial Respiratorio/inmunología , Virus Sincitial Respiratorio Humano/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Neutralizantes/inmunología , Línea Celular , Línea Celular Tumoral , Niño , Preescolar , Estudios de Cohortes , Epítopos/inmunología , Femenino , Células HEK293 , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Vacunación/métodos , Proteínas Virales de Fusión/inmunología , Adulto JovenRESUMEN
The site on the HIV-1 gp120 glycoprotein that binds the CD4 receptor is recognized by broadly reactive antibodies, several of which neutralize over 90% of HIV-1 strains. To understand how antibodies achieve such neutralization, we isolated CD4-binding-site (CD4bs) antibodies and analyzed 16 co-crystal structures -8 determined here- of CD4bs antibodies from 14 donors. The 16 antibodies segregated by recognition mode and developmental ontogeny into two types: CDR H3-dominated and VH-gene-restricted. Both could achieve greater than 80% neutralization breadth, and both could develop in the same donor. Although paratope chemistries differed, all 16 gp120-CD4bs antibody complexes showed geometric similarity, with antibody-neutralization breadth correlating with antibody-angle of approach relative to the most effective antibody of each type. The repertoire for effective recognition of the CD4 supersite thus comprises antibodies with distinct paratopes arrayed about two optimal geometric orientations, one achieved by CDR H3 ontogenies and the other achieved by VH-gene-restricted ontogenies.
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Anticuerpos Neutralizantes/química , Anticuerpos Antivirales/química , Proteína gp120 de Envoltorio del VIH/química , Proteína gp120 de Envoltorio del VIH/metabolismo , VIH-1/fisiología , Secuencia de Aminoácidos , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/metabolismo , Linfocitos B/inmunología , Antígenos CD4/metabolismo , Regiones Determinantes de Complementariedad , Epítopos de Linfocito B , Proteína gp120 de Envoltorio del VIH/inmunología , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Alineación de SecuenciaRESUMEN
Broadly neutralizing antibodies (bNAbs) against HIV-1 envelope (Env) inform vaccine design and are potential therapeutic agents. We identified SF12 and related bNAbs with up to 62% neutralization breadth from an HIV-infected donor. SF12 recognized a glycan-dominated epitope on Env's silent face and was potent against clade AE viruses, which are poorly covered by V3-glycan bNAbs. A 3.3Å cryo-EM structure of a SF12-Env trimer complex showed additional contacts to Env protein residues by SF12 compared with VRC-PG05, the only other known donor-derived silentface antibody, explaining SF12's increased neutralization breadth, potency, and resistance to Env mutation routes. Asymmetric binding of SF12 was associated with distinct N-glycan conformations across Env protomers, demonstrating intra-Env glycan heterogeneity. Administrating SF12 to HIV-1-infected humanized mice suppressed viremia and selected for viruses lacking the N448gp120 glycan. Effective bNAbs can therefore be raised against HIV-1 Env's silent face, suggesting their potential for HIV-1 prevention, therapy, and vaccine development.
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Anticuerpos Neutralizantes/inmunología , Anticuerpos Anti-VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Secuencia de Aminoácidos , Anticuerpos Neutralizantes/aislamiento & purificación , Afinidad de Anticuerpos/inmunología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Epítopos/química , Epítopos/inmunología , Glicosilación , Anticuerpos Anti-VIH/aislamiento & purificación , Proteína gp120 de Envoltorio del VIH/química , Proteína gp120 de Envoltorio del VIH/inmunología , Infecciones por VIH/virología , VIH-1/clasificación , VIH-1/genética , Humanos , Modelos Moleculares , Filogenia , Polisacáridos/química , Polisacáridos/metabolismo , Unión Proteica/inmunología , Conformación Proteica , Productos del Gen env del Virus de la Inmunodeficiencia Humana/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/genética , Productos del Gen env del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
The elicitation of broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope glycoprotein (Env) trimer remains a major vaccine challenge. Most cross-conserved protein determinants are occluded by self-N-glycan shielding, limiting B cell recognition of the underlying polypeptide surface. The exceptions to the contiguous glycan shield include the conserved receptor CD4 binding site (CD4bs) and glycoprotein (gp)41 elements proximal to the furin cleavage site. Accordingly, we performed heterologous trimer-liposome prime:boosting in rabbits to drive B cells specific for cross-conserved sites. To preferentially expose the CD4bs to B cells, we eliminated proximal N-glycans while maintaining the native-like state of the cleavage-independent NFL trimers, followed by gradual N-glycan restoration coupled with heterologous boosting. This approach successfully elicited CD4bs-directed, cross-neutralizing Abs, including one targeting a unique glycan-protein epitope and a bNAb (87% breadth) directed to the gp120:gp41 interface, both resolved by high-resolution cryoelectron microscopy. This study provides proof-of-principle immunogenicity toward eliciting bNAbs by vaccination.
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Vacunas contra el SIDA/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Anti-VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Liposomas , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Animales , Linfocitos B/inmunología , Linfocitos B/metabolismo , Antígenos CD4/química , Antígenos CD4/inmunología , Antígenos CD4/metabolismo , Complemento C3/inmunología , Complemento C3/metabolismo , Reactividad Cruzada/inmunología , Epítopos/inmunología , Glicosilación , Infecciones por VIH/virología , Humanos , Inmunoglobulina G/inmunología , Modelos Moleculares , Pruebas de Neutralización , Polisacáridos/inmunología , Polisacáridos/metabolismo , Unión Proteica , Conformación Proteica , Conejos , Productos del Gen env del Virus de la Inmunodeficiencia Humana/administración & dosificación , Productos del Gen env del Virus de la Inmunodeficiencia Humana/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
The global emergence of many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants jeopardizes the protective antiviral immunity induced after infection or vaccination. To address the public health threat caused by the increasing SARS-CoV-2 genomic diversity, the National Institute of Allergy and Infectious Diseases within the National Institutes of Health established the SARS-CoV-2 Assessment of Viral Evolution (SAVE) programme. This effort was designed to provide a real-time risk assessment of SARS-CoV-2 variants that could potentially affect the transmission, virulence, and resistance to infection- and vaccine-induced immunity. The SAVE programme is a critical data-generating component of the US Government SARS-CoV-2 Interagency Group to assess implications of SARS-CoV-2 variants on diagnostics, vaccines and therapeutics, and for communicating public health risk. Here we describe the coordinated approach used to identify and curate data about emerging variants, their impact on immunity and effects on vaccine protection using animal models. We report the development of reagents, methodologies, models and notable findings facilitated by this collaborative approach and identify future challenges. This programme is a template for the response to rapidly evolving pathogens with pandemic potential by monitoring viral evolution in the human population to identify variants that could reduce the effectiveness of countermeasures.
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COVID-19 , SARS-CoV-2 , Animales , Evolución Biológica , Vacunas contra la COVID-19 , Humanos , National Institute of Allergy and Infectious Diseases (U.S.) , Pandemias/prevención & control , Variantes Farmacogenómicas , SARS-CoV-2/genética , SARS-CoV-2/patogenicidad , Estados Unidos/epidemiología , VirulenciaRESUMEN
Most HIV-1-specific neutralizing antibodies isolated to date exhibit unusual characteristics that complicate their elicitation. Neutralizing antibodies that target the V1V2 apex of the HIV-1 envelope (Env) trimer feature unusually long protruding loops, which enable them to penetrate the HIV-1 glycan shield. As antibodies with loops of requisite length are created through uncommon recombination events, an alternative mode of apex binding has been sought. Here, we isolated a lineage of Env apex-directed neutralizing antibodies, N90-VRC38.01-11, by using virus-like particles and conformationally stabilized Env trimers as B cell probes. A crystal structure of N90-VRC38.01 with a scaffolded V1V2 revealed a binding mode involving side-chain-to-side-chain interactions that reduced the distance the antibody loop must traverse the glycan shield, thereby facilitating V1V2 binding via a non-protruding loop. The N90-VRC38 lineage thus identifies a solution for V1V2-apex binding that provides a more conventional B cell pathway for vaccine design.
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Anticuerpos Neutralizantes/inmunología , Anticuerpos Anti-VIH/inmunología , Proteína gp120 de Envoltorio del VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Fragmentos de Péptidos/inmunología , Conformación Proteica , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Secuencia de Aminoácidos , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/metabolismo , Linfocitos B/inmunología , Linfocitos B/metabolismo , Sitios de Unión , Regiones Determinantes de Complementariedad/química , Regiones Determinantes de Complementariedad/inmunología , Anticuerpos Anti-VIH/química , Anticuerpos Anti-VIH/metabolismo , Proteína gp120 de Envoltorio del VIH/química , Proteína gp120 de Envoltorio del VIH/metabolismo , Infecciones por VIH/virología , Humanos , Modelos Moleculares , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Filogenia , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Vacunas de Partículas Similares a Virus/química , Vacunas de Partículas Similares a Virus/inmunología , Vacunas de Partículas Similares a Virus/metabolismoRESUMEN
A vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is needed to control the coronavirus disease 2019 (COVID-19) global pandemic. Structural studies have led to the development of mutations that stabilize Betacoronavirus spike proteins in the prefusion state, improving their expression and increasing immunogenicity1. This principle has been applied to design mRNA-1273, an mRNA vaccine that encodes a SARS-CoV-2 spike protein that is stabilized in the prefusion conformation. Here we show that mRNA-1273 induces potent neutralizing antibody responses to both wild-type (D614) and D614G mutant2 SARS-CoV-2 as well as CD8+ T cell responses, and protects against SARS-CoV-2 infection in the lungs and noses of mice without evidence of immunopathology. mRNA-1273 is currently in a phase III trial to evaluate its efficacy.
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Betacoronavirus/inmunología , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/prevención & control , Pandemias/prevención & control , Neumonía Viral/inmunología , Neumonía Viral/prevención & control , Vacunas Virales/inmunología , Vacuna nCoV-2019 mRNA-1273 , Animales , Anticuerpos Neutralizantes/inmunología , Betacoronavirus/genética , Linfocitos T CD8-positivos/inmunología , COVID-19 , Vacunas contra la COVID-19 , Ensayos Clínicos Fase III como Asunto , Infecciones por Coronavirus/genética , Infecciones por Coronavirus/virología , Femenino , Pulmón/inmunología , Pulmón/virología , Ratones , Mutación , Nariz/inmunología , Nariz/virología , Neumonía Viral/virología , ARN Mensajero/genética , ARN Viral/genética , SARS-CoV-2 , Células TH1/inmunología , Receptor Toll-Like 4/agonistas , Receptor Toll-Like 4/inmunología , Vacunas Virales/química , Vacunas Virales/genéticaRESUMEN
Vaccines against HIV most likely need to elicit broadly neutralizing antibodies. In this issue of Immunity, Poignard and colleagues describe the co-evolution of a broadly neutralizing antibody and the virus that triggered it, providing a template for HIV vaccine design.
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Vacunas contra el SIDA/inmunología , Anticuerpos Anti-VIH/inmunología , Anticuerpos Neutralizantes/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , HumanosRESUMEN
Detailed studies of the broadly neutralizing antibodies (bNAbs) that underlie the best available examples of the humoral immune response to HIV are providing important information for the development of therapies and prophylaxis for HIV-1 infection. Here, we report a CD4-binding site (CD4bs) antibody, named N6, that potently neutralized 98% of HIV-1 isolates, including 16 of 20 that were resistant to other members of its class. N6 evolved a mode of recognition such that its binding was not impacted by the loss of individual contacts across the immunoglobulin heavy chain. In addition, structural analysis revealed that the orientation of N6 permitted it to avoid steric clashes with glycans, which is a common mechanism of resistance. Thus, an HIV-1-specific bNAb can achieve potent, near-pan neutralization of HIV-1, making it an attractive candidate for use in therapy and prophylaxis.
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Anticuerpos Neutralizantes/inmunología , Sitios de Unión de Anticuerpos/inmunología , Anticuerpos Anti-VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Especificidad de Anticuerpos , Linfocitos T CD4-Positivos/inmunología , Separación Celular , Proteína gp120 de Envoltorio del VIH/inmunología , HumanosRESUMEN
While neutralizing antibodies that target the HIV-1 fusion peptide have been elicited in mice by vaccination, antibodies reported thus far have been from only a single antibody class that could neutralize ~30% of HIV-1 strains. To explore the ability of the murine immune system to generate cross-clade neutralizing antibodies and to investigate how higher breadth and potency might be achieved, we tested 17 prime-boost regimens that utilized diverse fusion peptide-carrier conjugates and HIV-1 envelope trimers with different fusion peptides. We observed priming in mice with fusion peptide-carrier conjugates of variable peptide length to elicit higher neutralizing responses, a result we confirmed in guinea pigs. From vaccinated mice, we isolated 21 antibodies, belonging to 4 distinct classes of fusion peptide-directed antibodies capable of cross-clade neutralization. Top antibodies from each class collectively neutralized over 50% of a 208-strain panel. Structural analyses - both X-ray and cryo-EM - revealed each antibody class to recognize a distinct conformation of fusion peptide and to have a binding pocket capable of accommodating diverse fusion peptides. Murine vaccinations can thus elicit diverse neutralizing antibodies, and altering peptide length during prime can improve the elicitation of cross-clade responses targeting the fusion peptide site of HIV-1 vulnerability. IMPORTANCE The HIV-1 fusion peptide has been identified as a site for elicitation of broadly neutralizing antibodies, with prior studies demonstrating that priming with fusion peptide-based immunogens and boosting with soluble envelope (Env) trimers can elicit cross-clade HIV-1-neutralizing responses. To improve the neutralizing breadth and potency of fusion peptide-directed responses, we evaluated vaccine regimens that incorporated diverse fusion peptide-conjugates and Env trimers with variation in fusion peptide length and sequence. We found that variation in peptide length during prime elicits enhanced neutralizing responses in mice and guinea pigs. We identified vaccine-elicited murine monoclonal antibodies from distinct classes capable of cross-clade neutralization and of diverse fusion peptide recognition. Our findings lend insight into improved immunogens and regimens for HIV-1 vaccine development.
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Vacunas contra el SIDA , Infecciones por VIH , Seropositividad para VIH , VIH-1 , Animales , Cobayas , Ratones , Anticuerpos Anti-VIH , Isotipos de Inmunoglobulinas , Vacunación , Péptidos , Anticuerpos Neutralizantes , Anticuerpos ampliamente neutralizantes , Productos del Gen env del Virus de la Inmunodeficiencia Humana , Infecciones por VIH/prevención & controlRESUMEN
Both SIV and SHIV are powerful tools for evaluating antibody-mediated prevention and treatment of HIV-1. However, owing to a lack of rhesus-derived SIV broadly neutralizing antibodies (bnAbs), testing of bnAbs for HIV-1 prevention or treatment has thus far been performed exclusively in the SHIV NHP model using bnAbs from HIV-1-infected individuals. Here we describe the isolation and characterization of multiple rhesus-derived SIV bnAbs capable of neutralizing most isolates of SIV. Eight antibodies belonging to two clonal families, ITS102 and ITS103, which target unique epitopes in the CD4 binding site (CD4bs) region, were found to be broadly neutralizing and together neutralized all SIV strains tested. A rare feature of these bnAbs and two additional antibody families, ITS92 and ITS101, which mediate strain-specific neutralizing activity against SIV from sooty mangabeys (SIVsm), was their ability to achieve near complete (i.e. 100%) neutralization of moderately and highly neutralization-resistant SIV. Overall, these newly identified SIV bnAbs highlight the potential for evaluating HIV-1 prophylactic and therapeutic interventions using fully simian, rhesus-derived bnAbs in the SIV NHP model, thereby circumventing issues related to rapid antibody clearance of human-derived antibodies, Fc mismatch and limited genetic diversity of SHIV compared to SIV.
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Infecciones por VIH , VIH-1 , Virus de la Inmunodeficiencia de los Simios , Animales , Anticuerpos Neutralizantes , Anticuerpos ampliamente neutralizantes , Anticuerpos Anti-VIH , Macaca mulattaRESUMEN
Hepatitis B remains a public health problem worldwide despite vaccine availability. Although the existing diagnostic tools help detect the infection, logistics support and limited resources and technologies affect their usefulness and reliability in developing countries. This systematic review evaluated the performance of dried blood spots (DBS) as a collection and storage tool for diagnosing an hepatitis B virus (HBV) infection. A comprehensive search using OVID, Scopus and CINAHL databases was performed to collate articles published up to April 2023 that detected Hepatitis B infections using DBS. Five reviewers independently performed identification, screening, quality assessment and data extraction. A qualitative synthesis of the included studies was conducted. Of the 402 articles, 78 met the inclusion criteria. The results show that most studies focused on populations with known HBV, HCV and/or HIV status. Approximately half (49%) of the included studies utilized the Whatman Protein Saver Card for DBS collection. The DBS samples were then predominantly stored in room temperature conditions. In line with this, storage conditions influenced the concentration and stability of the analyte from the DBS samples, affecting the accuracy of downstream diagnostic methods. ELISA methods, using hepatitis B surface antigen (HBsAg) as an HBV marker, were the most widely used diagnostic tool for detecting HBV infection in DBS samples. The simplicity and cost-effectiveness of the ELISA technique highlight its potential to be used in low-resource settings. In line with this, the detection of HBsAg using an ELISA immunoassay had higher sensitivity (85.6%-100%), and specificity (95%-100%) ranges as compared to other target molecules and methods. Although this review only performed a qualitative analysis, DBS offers a promising method for collecting and storing blood samples; however, the standardization of sampling, storing conditions and diagnostic techniques is required to ensure sustainable application.
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Antígenos de Superficie de la Hepatitis B , Hepatitis B , Humanos , Reproducibilidad de los Resultados , Virus de la Hepatitis B , Ensayo de Inmunoadsorción Enzimática , Sensibilidad y EspecificidadRESUMEN
Vaccine-based elicitation of broadly neutralizing antibodies holds great promise for preventing HIV-1 transmission. However, the key biophysical markers of improved antibody recognition remain uncertain in the diverse landscape of potential antibody mutation pathways, and a more complete understanding of anti-HIV-1 fusion peptide (FP) antibody development will accelerate rational vaccine designs. Here we survey the mutational landscape of the vaccine-elicited anti-FP antibody, vFP16.02, to determine the genetic, structural, and functional features associated with antibody improvement or fitness. Using site-saturation mutagenesis and yeast display functional screening, we found that 1% of possible single mutations improved HIV-1 envelope trimer (Env) affinity, but generally comprised rare somatic hypermutations that may not arise frequently in vivo. We observed that many single mutations in the vFP16.02 Fab could enhance affinity >1,000-fold against soluble FP, although affinity improvements against the HIV-1 trimer were more measured and rare. The most potent variants enhanced affinity to both soluble FP and Env, had mutations concentrated in antibody framework regions, and achieved up to 37% neutralization breadth compared to 28% neutralization of the template antibody. Altered heavy- and light-chain interface angles and conformational dynamics, as well as reduced Fab thermal stability, were associated with improved HIV-1 neutralization breadth and potency. We also observed parallel sets of mutations that enhanced viral neutralization through similar structural mechanisms. These data provide a quantitative understanding of the mutational landscape for vaccine-elicited FP-directed broadly neutralizing antibody and demonstrate that numerous antigen-distal framework mutations can improve antibody function by enhancing affinity simultaneously toward HIV-1 Env and FP.
Asunto(s)
Vacunas contra el SIDA/inmunología , Anticuerpos ampliamente neutralizantes/inmunología , Anticuerpos Anti-VIH/inmunología , VIH-1/inmunología , Mutación , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Vacunas contra el SIDA/genética , Anticuerpos ampliamente neutralizantes/genética , Anticuerpos Anti-VIH/genética , VIH-1/genética , Humanos , Productos del Gen env del Virus de la Inmunodeficiencia Humana/genéticaRESUMEN
The conformationally dynamic HIV-1 envelope trimer (Env) is the target of broadly neutralizing antibodies (bnAbs) that block viral entry. Single-molecule Förster resonance energy transfer (smFRET) has revealed that HIV-1 Env exists in at least three conformational states on the virion. Prior to complete host-receptor engagement (State 3), Env resides most prevalently in the smFRET-defined State 1, which is preferentially recognized by most bnAbs that are elicited by natural infection. smFRET has also revealed that soluble trimers containing prefusion-stabilizing disulfide and isoleucine-to-proline substitutions reside primarily in State 2, which is a required intermediate between States 1 and 3. While high-resolution Env structures have been determined for States 2 and 3, the structure of these trimers in State 1 is unknown. To provide insight into the State 1 structure, here we characterized antigenic differences between smFRET-defined states and then correlated these differences with known structural differences between States 2 and 3. We found that cell surface-expressed Env was enriched in each state using state-enriching antibody fragments or small-molecule virus entry inhibitors and then assessed binding to HIV-1 bnAbs preferentially binding different states. We observed small but consistent differences in binding between Env enriched in States 1 and 2, and a more than 10-fold difference in binding to Env enriched in these states versus Env enriched in State 3. We conclude that structural differences between HIV-1 Env States 1 and 3 are likely more than 10-fold greater than those between States 1 and 2, providing important insight into State 1.