RESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuing to evolve around the world, generating new variants that are of concern on the basis of their potential for altered transmissibility, pathogenicity, and coverage by vaccines and therapeutic agents1-5. Here we show that serum samples taken from twenty human volunteers, two or four weeks after their second dose of the BNT162b2 vaccine, neutralize engineered SARS-CoV-2 with a USA-WA1/2020 genetic background (a virus strain isolated in January 2020) and spike glycoproteins from the recently identified B.1.617.1, B.1.617.2, B.1.618 (all of which were first identified in India) or B.1.525 (first identified in Nigeria) lineages. Geometric mean plaque reduction neutralization titres against the variant viruses-particularly the B.1.617.1 variant-seemed to be lower than the titre against the USA-WA1/2020 virus, but all sera tested neutralized the variant viruses at titres of at least 1:40. The susceptibility of the variant strains to neutralization elicited by the BNT162b2 vaccine supports mass immunization as a central strategy to end the coronavirus disease 2019 (COVID-19) pandemic globally.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , COVID-19/virología , Pruebas de Neutralización , SARS-CoV-2/inmunología , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Vacuna BNT162 , COVID-19/prevención & control , Vacunas contra la COVID-19/genética , Chlorocebus aethiops , Humanos , SARS-CoV-2/genética , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/inmunología , Vacunas Sintéticas/genética , Células Vero , Vacunas de ARNmRESUMEN
BNT162b2, a nucleoside-modified mRNA formulated in lipid nanoparticles that encodes the SARS-CoV-2 spike glycoprotein (S) stabilized in its prefusion conformation, has demonstrated 95% efficacy in preventing COVID-191. Here we extend a previous phase-I/II trial report2 by presenting data on the immune response induced by BNT162b2 prime-boost vaccination from an additional phase-I/II trial in healthy adults (18-55 years old). BNT162b2 elicited strong antibody responses: at one week after the boost, SARS-CoV-2 serum geometric mean 50% neutralizing titres were up to 3.3-fold above those observed in samples from individuals who had recovered from COVID-19. Sera elicited by BNT162b2 neutralized 22 pseudoviruses bearing the S of different SARS-CoV-2 variants. Most participants had a strong response of IFNγ+ or IL-2+ CD8+ and CD4+ T helper type 1 cells, which was detectable throughout the full observation period of nine weeks following the boost. Using peptide-MHC multimer technology, we identified several BNT162b2-induced epitopes that were presented by frequent MHC alleles and conserved in mutant strains. One week after the boost, epitope-specific CD8+ T cells of the early-differentiated effector-memory phenotype comprised 0.02-2.92% of total circulating CD8+ T cells and were detectable (0.01-0.28%) eight weeks later. In summary, BNT162b2 elicits an adaptive humoral and poly-specific cellular immune response against epitopes that are conserved in a broad range of variants, at well-tolerated doses.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , SARS-CoV-2/inmunología , Linfocitos T/inmunología , Adolescente , Adulto , Vacuna BNT162 , Linfocitos T CD8-positivos/inmunología , COVID-19/virología , Vacunas contra la COVID-19/administración & dosificación , Vacunas contra la COVID-19/efectos adversos , Epítopos de Linfocito T/inmunología , Femenino , Humanos , Inmunoglobulina G/inmunología , Memoria Inmunológica , Interferón gamma/inmunología , Interleucina-2/inmunología , Masculino , Persona de Mediana Edad , SARS-CoV-2/química , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/inmunología , Células TH1/inmunología , Adulto JovenRESUMEN
A safe and effective vaccine against COVID-19 is urgently needed in quantities that are sufficient to immunize large populations. Here we report the preclinical development of two vaccine candidates (BNT162b1 and BNT162b2) that contain nucleoside-modified messenger RNA that encodes immunogens derived from the spike glycoprotein (S) of SARS-CoV-2, formulated in lipid nanoparticles. BNT162b1 encodes a soluble, secreted trimerized receptor-binding domain (known as the RBD-foldon). BNT162b2 encodes the full-length transmembrane S glycoprotein, locked in its prefusion conformation by the substitution of two residues with proline (S(K986P/V987P); hereafter, S(P2) (also known as P2 S)). The flexibly tethered RBDs of the RBD-foldon bind to human ACE2 with high avidity. Approximately 20% of the S(P2) trimers are in the two-RBD 'down', one-RBD 'up' state. In mice, one intramuscular dose of either candidate vaccine elicits a dose-dependent antibody response with high virus-entry inhibition titres and strong T-helper-1 CD4+ and IFNγ+CD8+ T cell responses. Prime-boost vaccination of rhesus macaques (Macaca mulatta) with the BNT162b candidates elicits SARS-CoV-2-neutralizing geometric mean titres that are 8.2-18.2× that of a panel of SARS-CoV-2-convalescent human sera. The vaccine candidates protect macaques against challenge with SARS-CoV-2; in particular, BNT162b2 protects the lower respiratory tract against the presence of viral RNA and shows no evidence of disease enhancement. Both candidates are being evaluated in phase I trials in Germany and the USA1-3, and BNT162b2 is being evaluated in an ongoing global phase II/III trial (NCT04380701 and NCT04368728).
Asunto(s)
Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , COVID-19/prevención & control , Modelos Animales de Enfermedad , SARS-CoV-2/inmunología , Envejecimiento/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Antígenos Virales/química , Antígenos Virales/genética , Antígenos Virales/inmunología , Vacuna BNT162 , COVID-19/sangre , COVID-19/terapia , COVID-19/virología , Vacunas contra la COVID-19/administración & dosificación , Vacunas contra la COVID-19/química , Vacunas contra la COVID-19/genética , Línea Celular , Ensayos Clínicos como Asunto , Femenino , Humanos , Inmunización Pasiva , Internacionalidad , Macaca mulatta/inmunología , Macaca mulatta/virología , Masculino , Ratones , Ratones Endogámicos BALB C , Modelos Moleculares , Multimerización de Proteína , ARN Viral/análisis , Sistema Respiratorio/inmunología , Sistema Respiratorio/virología , SARS-CoV-2/química , SARS-CoV-2/genética , Solubilidad , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/inmunología , Linfocitos T/inmunología , Vacunación , Vacunas Sintéticas/administración & dosificación , Vacunas Sintéticas/química , Vacunas Sintéticas/genética , Vacunas Sintéticas/inmunología , Sueroterapia para COVID-19 , Vacunas de ARNmRESUMEN
An effective vaccine is needed to halt the spread of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. Recently, we reported safety, tolerability and antibody response data from an ongoing placebo-controlled, observer-blinded phase I/II coronavirus disease 2019 (COVID-19) vaccine trial with BNT162b1, a lipid nanoparticle-formulated nucleoside-modified mRNA that encodes the receptor binding domain (RBD) of the SARS-CoV-2 spike protein1. Here we present antibody and T cell responses after vaccination with BNT162b1 from a second, non-randomized open-label phase I/II trial in healthy adults, 18-55 years of age. Two doses of 1-50 µg of BNT162b1 elicited robust CD4+ and CD8+ T cell responses and strong antibody responses, with RBD-binding IgG concentrations clearly above those seen in serum from a cohort of individuals who had recovered from COVID-19. Geometric mean titres of SARS-CoV-2 serum-neutralizing antibodies on day 43 were 0.7-fold (1-µg dose) to 3.5-fold (50-µg dose) those of the recovered individuals. Immune sera broadly neutralized pseudoviruses with diverse SARS-CoV-2 spike variants. Most participants had T helper type 1 (TH1)-skewed T cell immune responses with RBD-specific CD8+ and CD4+ T cell expansion. Interferon-γ was produced by a large fraction of RBD-specific CD8+ and CD4+ T cells. The robust RBD-specific antibody, T cell and favourable cytokine responses induced by the BNT162b1 mRNA vaccine suggest that it has the potential to protect against COVID-19 through multiple beneficial mechanisms.
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Anticuerpos Antivirales/inmunología , Infecciones por Coronavirus/inmunología , Neumonía Viral/inmunología , Células TH1/inmunología , Vacunas Virales/inmunología , Adulto , Anticuerpos Neutralizantes/inmunología , Linfocitos T CD8-positivos/citología , Linfocitos T CD8-positivos/inmunología , COVID-19 , Vacunas contra la COVID-19 , Infecciones por Coronavirus/prevención & control , Citocinas/inmunología , Femenino , Alemania , Humanos , Inmunoglobulina G/inmunología , Masculino , Persona de Mediana Edad , Pandemias , Células TH1/citología , Vacunas Virales/administración & dosificación , Vacunas Virales/efectos adversos , Adulto JovenAsunto(s)
Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacunas contra la COVID-19 , COVID-19 , SARS-CoV-2 , Vacunas Combinadas , Humanos , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Vacunas Combinadas/inmunología , Vacunas Combinadas/uso terapéutico , SARS-CoV-2/inmunología , COVID-19/inmunología , COVID-19/terapia , COVID-19/virología , Vacunas contra la COVID-19/inmunología , Vacunas contra la COVID-19/uso terapéuticoAsunto(s)
Anticuerpos Neutralizantes/sangre , Vacunas contra la COVID-19/inmunología , COVID-19/inmunología , SARS-CoV-2/inmunología , Anticuerpos Antivirales/sangre , Vacuna BNT162 , COVID-19/prevención & control , Humanos , Mutación , SARS-CoV-2/genética , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/inmunología , Vacunas Sintéticas/inmunología , Vacunas de ARNmRESUMEN
UNLABELLED: Antivector immunity limits the response to homologous boosting for viral vector vaccines. Here, we describe a new, potent vaccine vector based on replication-competent vesicular stomatitis virus pseudotyped with the glycoprotein of the lymphocytic choriomeningitis virus (VSV-GP), which we previously showed to be safe in mice. In mice, VSV and VSV-GP encoding ovalbumin (OVA) as a model antigen (VSV-OVA and VSV-GP-OVA) induced equal levels of OVA-specific humoral and cellular immune responses upon a single immunization. However, boosting with the same vector was possible only for VSV-GP-OVA as neutralizing antibodies to VSV limited the immunogenicity of the VSV-OVA boost. OVA-specific cytotoxic T-lymphocyte (CTL) responses induced by VSV-GP-OVA were at least as potent as those induced by an adenoviral state-of-the-art vaccine vector and completely protected mice in a Listeria monocytogenes challenge model. VSV-GP is so far the only replication-competent vaccine vector that does not lose efficacy upon repeated application. IMPORTANCE: Although there has been great progress in treatment and prevention of infectious diseases in the past several years, effective vaccines against some of the most serious infections, e.g., AIDS, malaria, hepatitis C, or tuberculosis, are urgently needed. Here, several approaches based on viral vector vaccines are under development. However, for all viral vaccine vectors currently in clinical testing, repeated application is limited by neutralizing antibodies to the vector itself. Here, we have exploited the potential of vesicular stomatitis virus pseudotyped with the glycoprotein of the lymphocytic choriomeningitis virus (VSV-GP) as a vaccine platform. VSV-GP is the first replication-competent viral vector vaccine that does not induce vector-specific humoral immunity, i.e., neutralizing antibodies, and therefore can boost immune responses against a foreign antigen by repeated applications. The vector allows introduction of various antigens and therefore can serve as a platform technology for the development of novel vaccines against a broad spectrum of diseases.
Asunto(s)
Antígenos Virales/inmunología , Portadores de Fármacos , Virus de la Coriomeningitis Linfocítica/inmunología , Ovalbúmina/inmunología , Vacunación/métodos , Vesiculovirus/genética , Vacunas Virales/inmunología , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Vectores Genéticos , Ratones , Ratones Endogámicos C57BL , Linfocitos T Citotóxicos/inmunología , Vacunas Virales/administración & dosificaciónRESUMEN
Retroviral vectors (RVs) are powerful tools in clinical gene therapy. However, stable genomic integration of RVs can be oncogenic, as reported in several animal models and in clinical trials. Previously, we observed that T-cell receptor (TCR) polyclonal mature T cells are resistant to transformation after gammaretroviral transfer of (proto-)oncogenes, whereas TCR-oligoclonal T cells were transformable in the same setting. Here, we describe the induction of a mature T-cell lymphoma (MTCL) in TCR-oligoclonal OT-I transgenic T cells, transduced with an enhanced green fluorescent protein (EGFP)-encoding gammaretroviral vector. The tumor cells were of a mature T-cell phenotype and serially transplantable. Integration site analysis revealed a proviral hit in Janus kinase 1 (Jak1), which resulted in Jak1 overexpression and Jak/STAT-pathway activation, particularly via signal transducer and activator of transcription 3 (STAT3). Specific inhibition of Jak1 markedly delayed tumor growth. A systematic meta-analysis of available gene expression data on human mature T-cell lymphomas/leukemias confirmed the relevance of Jak/STAT overexpression in sporadic human T-cell tumorigenesis. To our knowledge, this is the first study to describe RV-associated insertional mutagenesis in mature T cells.
Asunto(s)
Linfoma de Células T/genética , Linfoma de Células T/terapia , Mutagénesis Insercional/métodos , Retroviridae/genética , Linfocitos T/metabolismo , Animales , Línea Celular Tumoral , Exones , Femenino , Vectores Genéticos , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Janus Quinasa 1/genética , Janus Quinasa 1/metabolismo , Linfoma de Células T/patología , Ratones , Fosforilación , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/metabolismo , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/metabolismo , Transducción de Señal , Transactivadores/genética , Transactivadores/metabolismoRESUMEN
SummaryWhat are variant-adapted COVID-19 vaccines?The COVID-19 vaccine developed by BioNTech and Pfizer is known as BNT162b2 (Comirnaty). BNT162b2 contains messenger RNA, or mRNA, from SARS-CoV-2. SARS-CoV-2 is the virus responsible for COVID-19. mRNA is a type of genetic material that contains the instructions that tell cells in the body how to make a protein. The mRNA in BNT162b2 tells the body to make one of the proteins from SARS-CoV-2 known as the spike protein.This teaches the body's defense system, known as the immune system, to recognize and respond to a SARS-CoV-2 infection.The BNT162b2 vaccine contains mRNA from the first SARS-CoV-2 virus, which was detected in December 2019. Since this original vaccine was developed, the SARS-CoV-2 virus has evolved, resulting in the appearance of new versions of the virus, known as variants. Certain variants that might be more concerning for public health are labeled as either 'variants of concern' or 'variants of interest' by the World Health Organization (WHO). Variants have differences in their proteins compared with the original virus that can affect how well the original vaccine works against them. Therefore, BioNTech and Pfizer developed updated versions of the BNT162b2 vaccine that contain mRNA from certain variants. These new vaccines are called variant-adapted COVID-19 mRNA vaccines.Another company, Moderna, has also developed their own variant-adapted versions of their COVID-19 mRNA vaccine, mRNA-1273 (SpikeVax).Variant-adapted vaccines can contain parts of the variant mRNA either in addition to, or instead of, that from the original virus. Vaccines that contain mRNA from two different viruses are known as bivalent, whereas vaccines that contain mRNA from a single virus are called monovalent.
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Vacunas contra la COVID-19 , COVID-19 , Humanos , Vacuna BNT162 , COVID-19/prevención & control , SARS-CoV-2 , Lenguaje , ARN Mensajero/genéticaRESUMEN
The Brighton Collaboration Benefit-Risk Assessment of VAccines by TechnolOgy (BRAVATO) Working Group evaluates the safety and other key features of new platform technology vaccines, including nucleic acid (RNA and DNA) vaccines. This manuscript uses the BRAVATO template to report the key considerations for a benefit-risk assessment of the coronavirus disease 2019 (COVID-19) mRNA-based vaccine BNT162b2 (Comirnaty®, or Pfizer-BioNTech COVID-19 vaccine) including the subsequent Original/Omicron BA.1, Original/Omicron BA.4-5 and Omicron XBB.1.5 variant-adapted vaccines developed by BioNTech and Pfizer to protect against COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Initial Emergency Use Authorizations or conditional Marketing Authorizations for the original BNT162b2 vaccine were granted based upon a favorable benefit-risk assessment taking into account clinical safety, immunogenicity, and efficacy data, which was subsequently reconfirmed for younger age groups, and by real world evidence data. In addition, the favorable benefit-risk assessment was maintained for the bivalent vaccines, developed against newly arising SARS-CoV-2 variants, with accumulating clinical trial data.
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Vacuna BNT162 , Vacunas contra la COVID-19 , COVID-19 , SARS-CoV-2 , Vacunas de ARNm , Humanos , Vacunas contra la COVID-19/efectos adversos , Vacunas contra la COVID-19/inmunología , Vacunas contra la COVID-19/administración & dosificación , COVID-19/prevención & control , Vacuna BNT162/inmunología , SARS-CoV-2/inmunología , SARS-CoV-2/genética , Medición de Riesgo , Vacunas Sintéticas/efectos adversos , Vacunas Sintéticas/inmunología , Inmunogenicidad VacunalRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure histories become increasingly complex through original and variant-adapted vaccines and infections with viral variants. Upon exposure to the highly altered Omicron spike glycoprotein, pre-immunized individuals predominantly mount recall responses of Wuhan-Hu-1 (wild-type)-imprinted memory B (BMEM) cells mostly targeting conserved non-neutralizing epitopes, leading to diminished Omicron neutralization. We investigated the impact of imprinting in individuals double/triple vaccinated with a wild-type-strain-based mRNA vaccine who, thereafter, had two consecutive exposures to Omicron BA.1 spike (breakthrough infection followed by BA.1-adapted vaccine). We found that depletion of conserved epitope-recognizing antibodies using a wild-type spike bait results in strongly diminished BA.1 neutralization. Furthermore, spike-specific BMEM cells recognizing conserved epitopes are much more prevalent than BA.1-specific BMEM cells. Our observations suggest that imprinted BMEM cell recall responses limit the induction of strain-specific responses even after two consecutive BA.1 spike exposures. Vaccine adaptation strategies need to consider that prior SARS-CoV-2 infections and vaccinations may cause persistent immune imprinting.
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Anticuerpos Neutralizantes , Anticuerpos Antivirales , COVID-19 , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Humanos , SARS-CoV-2/inmunología , COVID-19/inmunología , COVID-19/virología , Glicoproteína de la Espiga del Coronavirus/inmunología , Anticuerpos Antivirales/inmunología , Anticuerpos Neutralizantes/inmunología , Vacunas contra la COVID-19/inmunología , Epítopos/inmunología , Femenino , Persona de Mediana Edad , Adulto , Masculino , Células B de Memoria/inmunologíaRESUMEN
INTRODUCTION: The Omicron BA.1 variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and subsequent sub-lineages exhibit partial escape from neutralizing antibodies elicited by vaccines containing or encoding wild-type spike protein. In response to the emergence of Omicron sub-lineages, variant-adapted vaccines that contain or encode for Omicron spike protein components have been developed. AREAS COVERED: This review presents currently available clinical immunogenicity and safety data on Omicron variant-adapted versions of the BNT162b2 messenger RNA (mRNA) vaccine and summarizes the expected mechanism of action, and rationale for development, of these vaccines. In addition, challenges encountered during development and regulatory approval are discussed. EXPERT OPINION: Omicron-adapted BNT162b2 vaccines provide a wider breadth and potentially more durable protection against Omicron sub-lineages and antigenically aligned variants when compared with the original vaccine. As SARS-CoV-2 continues to evolve, further vaccine updates may be required. To facilitate this, a globally harmonized regulatory process for the transition to updated vaccines is needed. Next-generation vaccine approaches may provide broader protection against future variants.
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Vacuna BNT162 , COVID-19 , Humanos , COVID-19/prevención & control , Vacunas contra la COVID-19 , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus/genética , Anticuerpos Neutralizantes , Anticuerpos AntiviralesRESUMEN
The highly transmissible Omicron (B.1.1.529) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first detected in late 2021. Initial Omicron waves were primarily made up of sub-lineages BA.1 and/or BA.2, BA.4, and BA.5 subsequently became dominant in mid-2022, and several descendants of these sub-lineages have since emerged. Omicron infections have generally caused less severe disease on average than those caused by earlier variants of concern in healthy adult populations, at least, in part, due to increased population immunity. Nevertheless, healthcare systems in many countries, particularly those with low population immunity, have been overwhelmed by unprecedented surges in disease prevalence during Omicron waves. Pediatric admissions were also higher during Omicron waves compared with waves of previous variants of concern. All Omicron sub-lineages exhibit partial escape from wild-type (Wuhan-Hu 1) spike-based vaccine-elicited neutralizing antibodies, with sub-lineages with more enhanced immuno-evasive properties emerging over time. Evaluating vaccine effectiveness (VE) against Omicron sub-lineages has become challenging against a complex background of varying vaccine coverage, vaccine platforms, prior infection rates, and hybrid immunity. Original messenger RNA vaccine booster doses substantially improved VE against BA.1 or BA.2 symptomatic disease. However, protection against symptomatic disease waned, with reductions detected from 2 months after booster administration. While original vaccine-elicited CD8+ and CD4+ T-cell responses cross-recognize Omicron sub-lineages, thereby retaining protection against severe outcomes, variant-adapted vaccines are required to expand the breadth of B-cell responses and improve durability of protection. Variant-adapted vaccines were rolled out in late 2022 to increase overall protection against symptomatic and severe infections caused by Omicron sub-lineages and antigenically aligned variants with enhanced immune escape mechanisms.
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COVID-19 , Vacunas , Adulto , Humanos , Niño , COVID-19/epidemiología , COVID-19/prevención & control , SARS-CoV-2/genética , Eficacia de las Vacunas , Costo de EnfermedadRESUMEN
[This corrects the article DOI: 10.3389/fimmu.2023.1130539.].
RESUMEN
The ongoing COVID-19 pandemic is leading to the discovery of hundreds of novel SARS-CoV-2 variants daily. While most variants do not impact the course of the pandemic, some variants pose an increased risk when the acquired mutations allow better evasion of antibody neutralisation or increased transmissibility. Early detection of such high-risk variants (HRVs) is paramount for the proper management of the pandemic. However, experimental assays to determine immune evasion and transmissibility characteristics of new variants are resource-intensive and time-consuming, potentially leading to delays in appropriate responses by decision makers. Presented herein is a novel in silico approach combining spike (S) protein structure modelling and large protein transformer language models on S protein sequences to accurately rank SARS-CoV-2 variants for immune escape and fitness potential. Both metrics were experimentally validated using in vitro pseudovirus-based neutralisation test and binding assays and were subsequently combined to explore the changing landscape of the pandemic and to create an automated Early Warning System (EWS) capable of evaluating new variants in minutes and risk-monitoring variant lineages in near real-time. The system accurately pinpoints the putatively dangerous variants by selecting on average less than 0.3% of the novel variants each week. The EWS flagged all 16 variants designated by the World Health Organization (WHO) as variants of interest (VOIs) if applicable or variants of concern (VOCs) otherwise with an average lead time of more than one and a half months ahead of their designation as such.
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COVID-19 , SARS-CoV-2 , Humanos , Pandemias , Benchmarking , MutaciónRESUMEN
The emergence of SARS-CoV-2 at the end of 2019 required the swift development of a vaccine to address the pandemic. Nonclinical GLP-compliant studies in Wistar Han rats were initiated to assess the local tolerance, systemic toxicity, and immune response to four mRNA vaccine candidates encoding immunogens derived from the spike (S) glycoprotein of SARS-CoV-2, encapsulated in lipid nanoparticles (LNPs). Vaccine candidates were administered intramuscularly once weekly for three doses at 30 and/or 100 µg followed by a 3-week recovery period. Clinical pathology findings included higher white blood cell counts and acute phase reactant concentrations, lower platelet and reticulocyte counts, and lower RBC parameters. Microscopically, there was increased cellularity (lymphocytes) in the lymph nodes and spleen, increased hematopoiesis in the bone marrow and spleen, acute inflammation and edema at the injection site, and minimal hepatocellular vacuolation. These findings were generally attributed to the anticipated immune and inflammatory responses to the vaccines, except for hepatocyte vacuolation, which was interpreted to reflect hepatocyte LNP lipid uptake, was similar between candidates and resolved or partially recovered at the end of the recovery phase. These studies demonstrated safety and tolerability in rats, supporting SARS-CoV-2 mRNA-LNP vaccine clinical development.
RESUMEN
Evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has led to the emergence of sublineages with different patterns of neutralizing antibody evasion. We report that Omicron BA.4/BA.5 breakthrough infection of individuals immunized with SARS-CoV-2 wild-type-strain-based mRNA vaccines results in a boost of Omicron BA.4.6, BF.7, BQ.1.1, and BA.2.75 neutralization but does not efficiently boost BA.2.75.2, XBB, or XBB.1.5 neutralization. In silico analyses showed that the Omicron spike glycoprotein lost most neutralizing B cell epitopes, especially in sublineages BA.2.75.2, XBB, and XBB.1.5. In contrast, T cell epitopes are conserved across variants including XBB.1.5. T cell responses of mRNA-vaccinated, SARS-CoV-2-naive individuals against the wild-type strain, Omicron BA.1, and BA.4/BA.5 were comparable, suggesting that T cell immunity against recent sublineages including XBB.1.5 may remain largely unaffected. While some Omicron sublineages effectively evade B cell immunity, spike-protein-specific T cell immunity, due to the nature of polymorphic cell-mediated immune responses, may continue to contribute to prevention/limitation of severe COVID-19 manifestation.
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COVID-19 , Linfocitos T , Humanos , Glicoproteína de la Espiga del Coronavirus/genética , SARS-CoV-2 , Anticuerpos Neutralizantes , Anticuerpos AntiviralesRESUMEN
BACKGROUND: Humanized mouse models for adoptive T cell transfer are important for preclinical efficacy and toxicity studies. However, common xenograft models using immunodeficient mice have so far failed to efficiently support the homing of human T cells to secondary lymphoid tissues. METHODS: We established a new mouse model for the adoptive transfer of genetically-modified (gm) T cells using conditioned BALB/c mice. Conditioning involved cyclophosphamide injections, lethal irradiation and radioprotection with bone marrow from immunodeficient mice. We compared repopulation kinetics and the quality of grafts in these modified Trimera (mT3) mice with immunodeficient BALB/c Rag2(-/-) interleukin (IL)2 receptor gamma (rg) knockout (DKO) and NOD/LtSz-scid IL2rg(-/-) (NSG) recipient mouse strains. RESULTS: DKO mice showed only marginal engraftment until onset of graft-versus-host disease, whereas mT3 and NSG were repopulated with comparable kinetics. However, T cell repertoire and human cytokine profiles suggest a xenoreactivity-driven gm T cell expansion in mT3 mice, whereas NSG mice were characterized by an initial homeostatic proliferation. Morphological analysis revealed high levels of human gm T cell infiltration in the spleen and liver of all three mouse strains. However, mT3 mice provided the strongest homing of human gm T cells to mucosal sites. Additionally, mT3 mice were the only model with macroscopically visible superficial inguinal lymph nodes. These lymph nodes strongly supported the homing of gm T cells. CONCLUSIONS: In the present study, we give proof-of-concept that wild-type mice can accept gm T cell grafts while providing secondary lymphoid structures. Despite limitations, mT3 mice are a valid alternative for applications that specifically rely on improved secondary lymphoid structures.