RESUMEN
Introduction: Antibodies against the SARS-CoV-2 spike protein are a critical immune determinant for protection against the virus. While virus neutralization is a key function of spike-specific antibodies, antibodies also mediate Fc-dependent activities that can play a role in protection or pathogenesis. Methods: This study characterized serum antibody responses elicited after two doses of heterologous adenovirus-vectored (Ad26/ Ad5) vaccines. Results: Vaccine-induced antibody binding titers and Fc-mediated functions decreased over six months, while neutralization titers remained stable. Comparison of antibody isotypes elicited after Ad26/Ad5 vs. LNP-mRNA vaccination and after infection showed that anti-spike IgG1 were dominant and produced to high levels in all groups. The Ad26/Ad5 vaccines also induced IgG4 but not IgG2 and IgG3, whereas the LNP-mRNA vaccines elicited a full Ig spectrum (IgM, IgG1-4, IgA1-2). Convalescent COVID-19 patients had mainly IgM and IgA1 alongside IgG1. Despite these differences, the neutralization potencies against early variants were similar. However, both vaccine groups had antibodies with greater Fc potencies of binding complement and Fcg receptors than the COVID-19 group. The Ad26/Ad5 group also displayed a greater potency of RBD-specific antibody-mediated cellular phagocytosis. Discussion: Antibodies with distinctive quality were induced by different vaccines and infection. The data imply the utility of different vaccine platforms to elicit antibody responses with fine-tuned Fc activities.
Asunto(s)
Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacunas contra la COVID-19 , COVID-19 , Inmunoglobulina G , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Humanos , SARS-CoV-2/inmunología , Anticuerpos Antivirales/inmunología , Anticuerpos Antivirales/sangre , COVID-19/inmunología , COVID-19/prevención & control , Vacunas contra la COVID-19/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Glicoproteína de la Espiga del Coronavirus/genética , Femenino , Inmunoglobulina G/inmunología , Inmunoglobulina G/sangre , Anticuerpos Neutralizantes/inmunología , Anticuerpos Neutralizantes/sangre , Masculino , Fragmentos Fc de Inmunoglobulinas/inmunología , Fragmentos Fc de Inmunoglobulinas/genética , Ad26COVS1/inmunología , Adulto , Persona de Mediana Edad , Adenoviridae/inmunología , Adenoviridae/genética , Vectores Genéticos , Inmunoglobulina A/inmunología , Inmunoglobulina A/sangreRESUMEN
Optimized transfer RNA (tRNA) codon use can speed up antibody generation.
Asunto(s)
Formación de Anticuerpos , Uso de Codones , Inosina , ARN de Transferencia , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , Formación de Anticuerpos/genética , Código Genético , Inosina/genética , Inosina/metabolismo , HumanosRESUMEN
Despite SARS-CoV-2 being a "novel" virus, early detection of anti-spike IgG in severe COVID-19 patients may be caused by the amplification of humoral memory responses against seasonal coronaviruses. Here, we examine this phenomenon by characterizing anti-spike IgG responses in non-hospitalized convalescent individuals across a spectrum of COVID-19 severity. We observe that disease severity positively correlates with anti-spike IgG levels, IgG cross-reactivity against other betacoronaviruses (ß-CoVs), and FcγR activation. Analysis of IgG targeting ß-CoV-conserved and non-conserved immunodominant epitopes within the SARS-CoV-2 spike protein revealed epitope-specific relationships: IgG targeting the conserved heptad repeat (HR) 2 region significantly correlates with milder disease, while targeting the conserved S2'FP region correlates with more severe disease. Furthermore, a lower HR2-to-S2'FP IgG-binding ratio correlates with greater disease severity, with ICU-hospitalized COVID-19 patients showing the lowest HR2/S2'FP ratios. These findings suggest that HR2/S2'FP IgG profiles may predict disease severity and offer insight into protective versus deleterious humoral recall responses.
Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , Inmunoglobulina G , Estaciones del Año , Glicoproteína de la Espiga del CoronavirusRESUMEN
Andes virus, an orthohantavirus endemic to South America, causes severe hantavirus cardiopulmonary syndrome associated with human-to-human transmission. No approved treatments or vaccines against this virus are available. We show that a combined treatment with 2 monoclonal antibodies protected Syrian hamsters when administered at midstage or late-stage disease.
Asunto(s)
Infecciones por Hantavirus , Orthohantavirus , Animales , Anticuerpos Monoclonales/uso terapéutico , Cricetinae , Infecciones por Hantavirus/tratamiento farmacológico , Humanos , Mesocricetus , América del SurRESUMEN
During HIV-1 transmission through T cell virological synapses, the recruitment of the envelope (Env) glycoprotein to the site of cell-cell contact is important for adhesion and for packaging onto nascent virus particles which assemble at the site. Live imaging studies in CD4 T cells have captured the rapid recruitment of the viral structural protein Gag to VSs. We explored the role of endocytic trafficking of Env initiated by a membrane proximal tyrosine motif during HIV transfer into target cells and examined the factors that allow Gag and Env to be transferred together across the synapse. To facilitate tracking of Env in live cells, we adapted an Env tagging method and introduced a biotin acceptor peptide (BAP) into the V4 loop of Env gp120, enabling sensitive fluorescent tracking of V4-biotinylated Env. The BAP-tagged and biotinylated HIVs were replication-competent in cell-free and cell-to-cell infection assays. Live cell fluorescent imaging experiments showed rapid internalized cell surface Env on infected cells. Cell-cell transfer experiments conducted with the Env endocytosis mutant (Y712A) showed increased transfer of Env. Paradoxically, this increase in Env transfer was associated with significantly reduced Gag transfer into target cells, when compared to viral transfer associated with WT Env. This Y712A Env mutant also exhibited an altered Gag/biotin Env fluorescence ratio during transfer that correlated with decreased productive cell-to-cell infection. These results may suggest that the internalization of Env into recycling pools plays an important role in the coordinated transfer of Gag and Env across the VS, which optimizes productive infection in target cells.
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Biotina/metabolismo , Infecciones por VIH/transmisión , VIH-1/metabolismo , Biotina/análogos & derivados , Linfocitos T CD4-Positivos/virología , Membrana Celular , Infecciones por VIH/virología , Humanos , Virión/metabolismo , Ensamble de Virus , Internalización del Virus , Replicación Viral , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
HIV-1 viremic controllers (VC) spontaneously control infection without antiretroviral treatment. Several studies indicate that IgG Abs from VCs induce enhanced responses from immune effector cells. Since signaling through Fc-γ receptors (FCGRs) modulate these Ab-driven responses, here we examine if enhanced FCGR activation is a common feature of IgG from VCs. Using an infected cell-based system, we observed that VC IgG stimulated greater FCGR2A and FCGR3A activation as compared with noncontrollers, independent of the magnitude of HIV-specific Ab binding or virus neutralization activities. Multivariate regression analysis showed that enhanced FCGR signaling was a significant predictor of VC status as compared with chronically infected patients (CIP) on highly active antiretroviral therapy (HAART). Unsupervised hierarchical clustering of patient IgG functions primarily grouped VC IgG profiles by enhanced FCGR2A, FCGR3A, or dual signaling activity. Our findings demonstrate that enhanced FCGR signaling is a common and significant predictive feature of VC IgG, with VCs displaying a distinct spectrum of FCGR activation profiles. Thus, profiling FCGR activation may provide a useful method for screening and distinguishing protective anti-HIV IgG responses in HIV-infected patients and in monitoring HIV vaccination regimens.
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Infecciones por VIH/inmunología , VIH-1/inmunología , Inmunoglobulina G/inmunología , Receptores de IgG/inmunología , Viremia/inmunología , Terapia Antirretroviral Altamente Activa , Resistencia a la Enfermedad , Femenino , Infecciones por VIH/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Transducción de SeñalAsunto(s)
Comunicación Celular/fisiología , VIH-1/patogenicidad , Sinapsis Inmunológicas/virología , Linfocitos T/virología , Adhesión Celular/fisiología , Movimiento Celular/fisiología , Infecciones por VIH/transmisión , VIH-1/fisiología , Humanos , Sinapsis Inmunológicas/fisiología , Linfocitos T/fisiología , Ensamble de Virus/fisiologíaRESUMEN
UNLABELLED: The type I interferon-inducible factor tetherin retains virus particles on the surfaces of cells infected with vpu-deficient human immunodeficiency virus type 1 (HIV-1). While this mechanism inhibits cell-free viral spread, the immunological implications of tethered virus have not been investigated. We found that surface tetherin expression increased the antibody opsonization of vpu-deficient HIV-infected cells. The absence of Vpu also stimulated NK cell-activating FcγRIIIa signaling and enhanced NK cell degranulation and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). The deletion of vpu in HIV-1-infected primary CD4(+) T cells enhanced the levels of antibody binding and Fc receptor signaling mediated by HIV-positive-patient-derived antibodies. The magnitudes of antibody binding and Fc signaling were both highly correlated to the levels of tetherin on the surfaces of infected primary CD4 T cells. The affinity of antibody binding to FcγRIIIa was also found to be critical in mediating efficient Fc activation. These studies implicate Vpu antagonism of tetherin as an ADCC evasion mechanism that prevents antibody-mediated clearance of virally infected cells. IMPORTANCE: The ability of the HIV-1 accessory factor to antagonize tetherin has been considered to primarily function by limiting the spread of virus by preventing the release of cell-free virus. This study supports the hypothesis that a major function of Vpu is to decrease the recognition of infected cells by anti-HIV antibodies at the cell surface, thereby reducing recognition by antibody-dependent clearance by natural killer cells.
Asunto(s)
Citotoxicidad Celular Dependiente de Anticuerpos/inmunología , Antígenos CD/inmunología , Proteínas del Virus de la Inmunodeficiencia Humana/inmunología , Células Asesinas Naturales/inmunología , Receptores de IgG/inmunología , Transducción de Señal/inmunología , Proteínas Reguladoras y Accesorias Virales/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/virología , Citometría de Flujo , Proteínas Ligadas a GPI/antagonistas & inhibidores , Proteínas Ligadas a GPI/inmunología , Humanos , Células Jurkat , Proteína 1 de la Membrana Asociada a los Lisosomas/inmunología , Proteínas Opsoninas/inmunología , Receptores de IgG/metabolismoRESUMEN
The female genital epithelium plays a protective role against invading pathogens; however, sexual transmission of human immunodeficiency virus type 1 (HIV-1) still occurs in healthy women. To model virus-cell interactions in this barrier during sexual transmission, we studied the uptake and infection of ectocervical and endocervical cell lines with cell-free fluorescent protein-expressing recombinant HIV-1 carrying primary transmitted/founder envelope genes. We observed that a subset of both the ectocervical and endocervical epithelial cells become productively infected with cell-free HIV-1 in a CD4-independent manner. In addition, the ability of the semen-derived enhancer of virus infection (SEVI) to enhance virus-epithelial cell interactions was studied. This infection is increased approximately 2-5 fold when inoculation occurs in the presence of SEVI fibrils. Once infected, the epithelial cells are capable of transmitting the virus to target CD4 T cells in coculture in a contact-dependent manner that uses conventional CD4- and coreceptor-dependent entry. The infection of target CD4 T cells only occurs when de novo HIV-1 is produced within the epithelial cells. These findings suggest that a subset of cervical epithelial cells may be actively involved in establishing a systemic HIV infection and should be a target when designing prevention strategies to protect against HIV-1 sexual transmission.
Asunto(s)
Linfocitos T CD4-Positivos/virología , Cuello del Útero/virología , Células Epiteliales/virología , Infecciones por VIH/transmisión , VIH-1/fisiología , Linfocitos T CD4-Positivos/inmunología , Línea Celular , Cuello del Útero/citología , Cuello del Útero/inmunología , Células Epiteliales/citología , Células Epiteliales/inmunología , Femenino , Regulación Viral de la Expresión Génica , Infecciones por VIH/inmunología , Infecciones por VIH/virología , VIH-1/inmunología , Interacciones Huésped-Patógeno , Humanos , ARN Viral/genética , ARN Viral/aislamiento & purificación , Internalización del VirusRESUMEN
An elaborate network of cell-cell interactions in the immune system is essential for vertebrates to mount adaptive immune responses against invading pathogens. For lymphotropic viruses such as the human immunodeficiency virus type 1 (HIV-1), these immune cell interactions can also promote the spread of the virus within the host. The main target of HIV-1 infection is the CD4(+) helper T lymphocyte, a cell type that is responsible for coordinating immune responses and modulating effector responses to foreign antigens. As part of their normal immune surveillance duties, these cells migrate actively within lymphoid tissues and can travel from inductive sites to effector sites in search of their cognate antigen. For CD4(+) T cells, there is an ongoing search for a unique peptide antigen presented in the context of class II MHC that can activate a proliferative or tolerogenic response. This iterative and continual probing and interrogation of other cells determine the outcome of immune responses. Recent studies in vitro have revealed that the viral infection program induces cell-cell interactions called virological synapses between infected and uninfected CD4(+) T cells. These long-lived, virally induced adhesive contacts greatly enhance the rate of productive infection and may be central to the spread of the virus in vivo. Here, we review aspects of this efficient mode of cell-to-cell infection and the implications for our understanding of HIV-1 pathogenesis.
Asunto(s)
Linfocitos T CD4-Positivos/virología , Infecciones por VIH/inmunología , VIH-1/fisiología , Interacciones Huésped-Patógeno/inmunología , Sinapsis Inmunológicas/virología , Inmunidad Adaptativa , Animales , Comunicación Celular/inmunología , HumanosRESUMEN
BACKGROUND: Elucidating mechanisms that promote HIV-1 transfer between CD4+ T-lymphocytes and their subsequent loss is of importance to HIV-1 pathogenesis. We recently reported that whey acidic protein, ps20, promotes cell-free HIV-1 spread through ICAM-1 modulation. Since ICAM-1 is pivotal in cell conjugation and intercellular HIV-1 transfer, this study examines ps20 effects on HIV-1 spread between T lymphocytes. RESULTS: We demonstrate intrinsic ps20 variability in primary CD4+ T-lymphocyte clonal populations and a significant positive correlation between endogenous ps20 levels and virus transfer involving fusion resulting in a spreading infection that could be reversed by the addition of reverse transcriptase inhibitors. Blocking anti-ps20 antibody or siRNA mediated ps20 knockdown, significantly reduced virus transfer. Conversely, virus transfer was promoted by ectopic ps20 expression or by exogenous addition of recombinant ps20. A higher frequency of virological synapse formation was evident in cocultures of HIV-1 infected donor T-cells with ps20high v ps20low/intermediate targets. Blocking ps20 inhibited T-lymphocyte conjugate formation and ICAM-1 expression, and was as potent as ICAM-1 in inhibiting HIV-1 transfer. CONCLUSIONS: Therefore ps20 is a novel marker of CD4+ T-cells rendered vulnerable to HIV-1 infection by regulating the fundamental biologic process of intercellular conjugate formation and consequently of potential importance in HIV-1 pathogenesis.
Asunto(s)
Linfocitos T CD4-Positivos/fisiología , Linfocitos T CD4-Positivos/virología , VIH-1/crecimiento & desarrollo , VIH-1/patogenicidad , Proteínas/análisis , Subgrupos de Linfocitos T/fisiología , Subgrupos de Linfocitos T/virología , Linfocitos T CD4-Positivos/química , Adhesión Celular , Fusión Celular , Humanos , Células Jurkat , Subgrupos de Linfocitos T/químicaRESUMEN
Pancreatic islet endothelial cells (ECs) form the barrier across which autoreactive T cells transmigrate during the development of islet inflammation in type 1 diabetes. Little is known about the immune phenotype of islet ECs that might shape their molecular interaction with autoreactive T cells before and during the development of islet inflammation. In this study we examined the expression and functional significance of costimulatory molecules by human islet ECs. Freshly isolated human islet ECs constitutively expressed CD86 (B7-2) and ICOS ligand but not CD80 (B7-1) or CD40 costimulatory molecules. The functional activity of islet EC-expressed CD86 was examined by coculture of resting islet ECs with CD4 T cells stimulated by CD3 ligation alone. Marked T cell proliferation in the coculture was completely abrogated by mAb blockade of CD86, confirming that costimulatory properties are conferred on ECs by CD86 expression. In view of its location on the vasculature, we hypothesized a role for CD86 in T cell adhesion/transmigration. In keeping with this, adhesion/transmigration of activated (CD3 ligated) memory (CD45R0(+)) CD4 T cells across islet ECs was completely inhibited in the presence of CD86 blocking mAb. Identical results were obtained for T cell adhesion using either CTLA-4 blocking mAb or CTLA-4Ig (abatacept), indicating CTLA-4 as the T cell ligand for these CD86-mediated effects. These data suggest a novel role for CD86 expression on the microvasculature, whereby ligation of CTLA-4 on CD4 T cells by CD86 on islet ECs is key to the adhesion of recently activated T cells.