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1.
Nat Immunol ; 23(1): 50-61, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34853448

RESUMO

NP105-113-B*07:02-specific CD8+ T cell responses are considered among the most dominant in SARS-CoV-2-infected individuals. We found strong association of this response with mild disease. Analysis of NP105-113-B*07:02-specific T cell clones and single-cell sequencing were performed concurrently, with functional avidity and antiviral efficacy assessed using an in vitro SARS-CoV-2 infection system, and were correlated with T cell receptor usage, transcriptome signature and disease severity (acute n = 77, convalescent n = 52). We demonstrated a beneficial association of NP105-113-B*07:02-specific T cells in COVID-19 disease progression, linked with expansion of T cell precursors, high functional avidity and antiviral effector function. Broad immune memory pools were narrowed postinfection but NP105-113-B*07:02-specific T cells were maintained 6 months after infection with preserved antiviral efficacy to the SARS-CoV-2 Victoria strain, as well as Alpha, Beta, Gamma and Delta variants. Our data show that NP105-113-B*07:02-specific T cell responses associate with mild disease and high antiviral efficacy, pointing to inclusion for future vaccine design.


Assuntos
Antígeno HLA-B7/imunologia , Epitopos Imunodominantes/imunologia , Proteínas do Nucleocapsídeo/imunologia , SARS-CoV-2/imunologia , Linfócitos T Citotóxicos/imunologia , Idoso , Sequência de Aminoácidos , Anticorpos Antivirais/imunologia , Afinidade de Anticorpos/imunologia , COVID-19/imunologia , COVID-19/patologia , Linhagem Celular Transformada , Feminino , Perfilação da Expressão Gênica , Humanos , Memória Imunológica/imunologia , Masculino , Pessoa de Meia-Idade , Receptores de Antígenos de Linfócitos T/imunologia , Índice de Gravidade de Doença , Vaccinia virus/genética , Vaccinia virus/imunologia , Vaccinia virus/metabolismo
2.
EMBO Rep ; 22(8): e52447, 2021 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-34142428

RESUMO

Cyclic GMP-AMP (cGAMP) is an immunostimulatory molecule produced by cGAS that activates STING. cGAMP is an adjuvant when administered alongside antigens. cGAMP is also incorporated into enveloped virus particles during budding. Here, we investigate whether inclusion of cGAMP within viral vaccine vectors enhances their immunogenicity. We immunise mice with virus-like particles (VLPs) containing HIV-1 Gag and the vesicular stomatitis virus envelope glycoprotein G (VSV-G). cGAMP loading of VLPs augments CD4 and CD8 T-cell responses. It also increases VLP- and VSV-G-specific antibody titres in a STING-dependent manner and enhances virus neutralisation, accompanied by increased numbers of T follicular helper cells. Vaccination with cGAMP-loaded VLPs containing haemagglutinin induces high titres of influenza A virus neutralising antibodies and confers protection upon virus challenge. This requires cGAMP inclusion within VLPs and is achieved at markedly reduced cGAMP doses. Similarly, cGAMP loading of VLPs containing the SARS-CoV-2 Spike protein enhances Spike-specific antibody titres. cGAMP-loaded VLPs are thus an attractive platform for vaccination.


Assuntos
COVID-19 , Vacinas contra Influenza , Vacinas de Partículas Semelhantes a Vírus , Animais , Humanos , Camundongos , Nucleotídeos Cíclicos , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Vacinas de Partículas Semelhantes a Vírus/genética
3.
Mol Ther ; 30(12): 3639-3657, 2022 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-35949171

RESUMO

Adenovirus vector vaccines have been widely and successfully deployed in response to coronavirus disease 2019 (COVID-19). However, despite inducing potent T cell immunity, improvement of vaccine-specific antibody responses upon homologous boosting is modest compared with other technologies. Here, we describe a system enabling modular decoration of adenovirus capsid surfaces with antigens and demonstrate potent induction of humoral immunity against these displayed antigens. Ligand attachment via a covalent bond was achieved using a protein superglue, DogTag/DogCatcher (similar to SpyTag/SpyCatcher), in a rapid and spontaneous reaction requiring only co-incubation of ligand and vector components. DogTag was inserted into surface-exposed loops in the adenovirus hexon protein to allow attachment of DogCatcher-fused ligands on virus particles. Efficient coverage of the capsid surface was achieved using various ligands, with vector infectivity retained in each case. Capsid decoration shielded particles from vector neutralizing antibodies. In prime-boost regimens, adenovirus vectors decorated with the receptor-binding domain of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike induced >10-fold higher SARS-CoV-2 neutralization titers compared with an undecorated vector encoding spike. Importantly, decorated vectors achieved equivalent or superior T cell immunogenicity against encoded antigens compared with undecorated vectors. We propose capsid decoration using protein superglues as a novel strategy to improve efficacy and boostability of adenovirus-based vaccines and therapeutics.


Assuntos
Vacinas contra Adenovirus , COVID-19 , Humanos , SARS-CoV-2 , Imunidade Humoral , Ligantes , COVID-19/prevenção & controle
4.
PLoS Pathog ; 14(5): e1006986, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29746590

RESUMO

Inducing broad spectrum neutralizing antibodies against challenging pathogens such as HIV-1 is a major vaccine design goal, but may be hindered by conformational instability within viral envelope glycoproteins (Env). Chemical cross-linking is widely used for vaccine antigen stabilization, but how this process affects structure, antigenicity and immunogenicity is poorly understood and its use remains entirely empirical. We have solved the first cryo-EM structure of a cross-linked vaccine antigen. The 4.2 Å structure of HIV-1 BG505 SOSIP soluble recombinant Env in complex with a CD4 binding site-specific broadly neutralizing antibody (bNAb) Fab fragment reveals how cross-linking affects key properties of the trimer. We observed density corresponding to highly specific glutaraldehyde (GLA) cross-links between gp120 monomers at the trimer apex and between gp120 and gp41 at the trimer interface that had strikingly little impact on overall trimer conformation, but critically enhanced trimer stability and improved Env antigenicity. Cross-links were also observed within gp120 at sites associated with the N241/N289 glycan hole that locally modified trimer antigenicity. In immunogenicity studies, the neutralizing antibody response to cross-linked trimers showed modest but significantly greater breadth against a global panel of difficult-to-neutralize Tier-2 heterologous viruses. Moreover, the specificity of autologous Tier-2 neutralization was modified away from the N241/N289 glycan hole, implying a novel specificity. Finally, we have investigated for the first time T helper cell responses to next-generation soluble trimers, and report on vaccine-relevant immunodominant responses to epitopes within BG505 that are modified by cross-linking. Elucidation of the structural correlates of a cross-linked viral glycoprotein will allow more rational use of this methodology for vaccine design, and reveals a strategy with promise for eliciting neutralizing antibodies needed for an effective HIV-1 vaccine.


Assuntos
HIV-1/química , HIV-1/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Vacinas contra a AIDS/química , Vacinas contra a AIDS/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Especificidade de Anticorpos , Reações Antígeno-Anticorpo/imunologia , Reagentes de Ligações Cruzadas , Microscopia Crioeletrônica , Anticorpos Anti-HIV/imunologia , Antígenos HIV/química , Antígenos HIV/imunologia , Antígenos HIV/ultraestrutura , Interações Hospedeiro-Patógeno/imunologia , Humanos , Epitopos Imunodominantes/química , Epitopos Imunodominantes/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Conformação Proteica , Estabilidade Proteica , Estrutura Quaternária de Proteína , Coelhos , Linfócitos T Auxiliares-Indutores/imunologia , Vacinas Sintéticas/química , Vacinas Sintéticas/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/ultraestrutura
5.
J Virol ; 90(2): 813-28, 2016 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-26512083

RESUMO

UNLABELLED: Major neutralizing antibody immune evasion strategies of the HIV-1 envelope glycoprotein (Env) trimer include conformational and structural instability. Stabilized soluble trimers such as BG505 SOSIP.664 mimic the structure of virion-associated Env but nevertheless sample different conformational states. Here we demonstrate that treating BG505 SOSIP.664 trimers with glutaraldehyde or a heterobifunctional cross-linker introduces additional stability with relatively modest effects on antigenicity. Thus, most broadly neutralizing antibody (bNAb) epitopes were preserved after cross-linking, whereas the binding of most weakly or nonneutralizing antibodies (non-NAb) was reduced. Cross-linking stabilized all Env conformers present within a mixed population, and individual conformers could be isolated by bNAb affinity chromatography. Both positive selection of cross-linked conformers using the quaternary epitope-specific bNAbs PGT145, PGT151, and 3BC315 and negative selection with non-NAbs against the V3 region enriched for trimer populations with improved antigenicity for bNAbs. Similar results were obtained using the clade B B41 SOSIP.664 trimer. The cross-linking method may, therefore, be useful for countering the natural conformational heterogeneity of some HIV-1 Env proteins and, by extrapolation, also vaccine immunogens from other pathogens. IMPORTANCE: The development of a vaccine to induce protective antibodies against HIV-1 is of primary public health importance. Recent advances in immunogen design have provided soluble recombinant envelope glycoprotein trimers with near-native morphology and antigenicity. However, these trimers are conformationally flexible, potentially reducing B-cell recognition of neutralizing antibody epitopes. Here we show that chemical cross-linking increases trimer stability, reducing binding of nonneutralizing antibodies while largely maintaining neutralizing antibody binding. Cross-linking followed by positive or negative antibody affinity selection of individual stable conformational variants further improved the antigenic and morphological characteristics of the trimers. This approach may be generally applicable to HIV-1 Env and also to other conformationally flexible pathogen antigens.


Assuntos
Antígenos HIV/imunologia , Antígenos HIV/metabolismo , HIV-1/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismo , Anticorpos Neutralizantes/imunologia , Reagentes de Ligações Cruzadas/metabolismo , Anticorpos Anti-HIV/imunologia , Humanos
6.
J Virol ; 88(4): 2025-34, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24307588

RESUMO

Macrophage infection is considered to play an important role in HIV-1 pathogenesis and persistence. Using a primary cell-based coculture model, we show that monocyte-derived macrophages (MDM) efficiently transmit a high-multiplicity HIV-1 infection to autologous CD4(+) T cells through a viral envelope glycoprotein (Env) receptor- and actin-dependent virological synapse (VS), facilitated by interactions between ICAM-1 and LFA-1. Virological synapse (VS)-mediated transmission by MDM results in high levels of T cell HIV-1 integration and is 1 to 2 orders of magnitude more efficient than cell-free infection. This mode of cell-to-cell transmission is broadly susceptible to the activity of CD4 binding site (CD4bs) and glycan or glycopeptide epitope-specific broadly neutralizing monoclonal antibodies (bNMAbs) but shows resistance to bNMAbs targeting the Env gp41 subunit membrane-proximal external region (MPER). These data define for the first time the structure and function of the macrophage-to-T cell VS and have important implications for bNMAb activity in HIV-1 prophylaxis and therapy. IMPORTANCE The ability of HIV-1 to move directly between contacting immune cells allows efficient viral dissemination with the potential to evade antibody attack. Here, we show that HIV-1 spreads from infected macrophages to T cells via a structure called a virological synapse that maintains extended contact between the two cell types, allowing transfer of multiple infectious events to the T cell. This process allows the virus to avoid neutralization by a class of antibody targeting the gp41 subunit of the envelope glycoproteins. These results have implications for viral spread in vivo and the specificities of neutralizing antibody elicited by antibody-based vaccines.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Linfócitos T CD4-Positivos/imunologia , Infecções por HIV/transmissão , Evasão da Resposta Imune/imunologia , Sinapses Imunológicas/virologia , Macrófagos/imunologia , Análise de Variância , Antígenos CD4/metabolismo , Linfócitos T CD4-Positivos/virologia , Primers do DNA/genética , Proteína gp41 do Envelope de HIV/imunologia , Infecções por HIV/imunologia , Molécula 1 de Adesão Intercelular/metabolismo , Luciferases , Antígeno-1 Associado à Função Linfocitária/metabolismo , Macrófagos/virologia , Microscopia Confocal , Testes de Neutralização , Reação em Cadeia da Polimerase , Imagem com Lapso de Tempo
7.
Nat Commun ; 15(1): 541, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38225245

RESUMO

Efferocytic clearance of apoptotic cells in general, and T cells in particular, is required for tissue and immune homeostasis. Transmembrane mucins are extended glycoproteins highly expressed in the cell glycocalyx that function as a barrier to phagocytosis. Whether and how mucins may be regulated during cell death to facilitate efferocytic corpse clearance is not well understood. Here we show that normal and transformed human T cells express a subset of mucins which are rapidly and selectively removed from the cell surface during apoptosis. This process is mediated by the ADAM10 sheddase, the activity of which is associated with XKR8-catalyzed flipping of phosphatidylserine to the outer leaflet of the plasma membrane. Mucin clearance enhances uptake of apoptotic T cells by macrophages, confirming mucins as an enzymatically-modulatable barrier to efferocytosis. Together these findings demonstrate a glycocalyx regulatory pathway with implications for therapeutic intervention in the clearance of normal and transformed apoptotic T cells.


Assuntos
Eferocitose , Mucinas , Humanos , Linfócitos T/metabolismo , Apoptose , Fagocitose , Proteína ADAM10/genética , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Secretases da Proteína Precursora do Amiloide
8.
NPJ Vaccines ; 8(1): 101, 2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37443366

RESUMO

Chemical cross-linking is used to stabilize protein structures with additional benefits of pathogen and toxin inactivation for vaccine use, but its use has been restricted by the potential for local or global structural distortion. This is of particular importance when the protein in question requires a high degree of structural conservation for inducing a biological outcome such as the elicitation of antibodies to conformationally sensitive epitopes. The HIV-1 envelope glycoprotein (Env) trimer is metastable and shifts between different conformational states, complicating its use as a vaccine antigen. Here we have used the hetero-bifunctional zero-length reagent 1-Ethyl-3-(3-Dimethylaminopropyl)-Carbodiimide (EDC) to cross-link two soluble Env trimers, selected well-folded trimer species using antibody affinity, and transferred this process to good manufacturing practice (GMP) for experimental medicine use. Cross-linking enhanced trimer stability to biophysical and enzyme attack. Cryo-EM analysis revealed that cross-linking retained the overall structure with root-mean-square deviations (RMSDs) between unmodified and cross-linked Env trimers of 0.4-0.5 Å. Despite this negligible distortion of global trimer structure, we identified individual inter-subunit, intra-subunit, and intra-protomer cross-links. Antigenicity and immunogenicity of the trimers were selectively modified by cross-linking, with cross-linked ConS retaining bnAb binding more consistently than ConM. Thus, the EDC cross-linking process improves trimer stability whilst maintaining protein folding, and is readily transferred to GMP, consistent with the more general use of this approach in protein-based vaccine design.

9.
NPJ Vaccines ; 7(1): 27, 2022 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-35228534

RESUMO

Soluble HIV-1 envelope glycoprotein (Env) immunogens are a prime constituent of candidate vaccines designed to induce broadly neutralizing antibodies. Several lines of evidence suggest that enhancing Env immunogen thermostability can improve neutralizing antibody (NAb) responses. Here, we generated BG505 SOSIP.v9 trimers, which displayed virtually no reactivity with non-neutralizing antibodies and showed increased global and epitope thermostability, compared to previous BG505 SOSIP versions. Chemical crosslinking of BG505 SOSIP.v9 further increased the melting temperature to 91.3 °C, which is almost 25 °C higher than that of the prototype SOSIP.664 trimer. Next, we compared the immunogenicity of a palette of BG505-based SOSIP trimers with a gradient of thermostabilities in rabbits. We also included SOSIP.v9 proteins in which a strain-specific immunodominant epitope was masked by glycans to redirect the NAb response to other subdominant epitopes. We found that increased trimer thermostability correlated with increased potency and consistency of the autologous NAb response. Furthermore, glycan masking steered the NAb response to subdominant epitopes without decreasing the potency of the autologous NAb response. In summary, SOSIP.v9 trimers and their glycan masked versions represent an improved platform for HIV-1 Env based vaccination strategies.

10.
PLoS Pathog ; 5(4): e1000367, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19343218

RESUMO

The role of APOBEC3 (A3) protein family members in inhibiting retrovirus infection and mobile element retrotransposition is well established. However, the evolutionary effects these restriction factors may have had on active retroviruses such as HIV-1 are less well understood. An HIV-1 variant that has been highly G-to-A mutated is unlikely to be transmitted due to accumulation of deleterious mutations. However, G-to-A mutated hA3G target sequences within which the mutations are the least deleterious are more likely to survive selection pressure. Thus, among hA3G targets in HIV-1, the ratio of nonsynonymous to synonymous changes will increase with virus generations, leaving a footprint of past activity. To study such footprints in HIV-1 evolution, we developed an in silico model based on calculated hA3G target probabilities derived from G-to-A mutation sequence contexts in the literature. We simulated G-to-A changes iteratively in independent sequential HIV-1 infections until a stop codon was introduced into any gene. In addition to our simulation results, we observed higher ratios of nonsynonymous to synonymous mutation at hA3G targets in extant HIV-1 genomes than in their putative ancestral genomes, compared to random controls, implying that moderate levels of A3G-mediated G-to-A mutation have been a factor in HIV-1 evolution. Results from in vitro passaging experiments of HIV-1 modified to be highly susceptible to hA3G mutagenesis verified our simulation accuracy. We also used our simulation to examine the possible role of A3G-induced mutations in the origin of drug resistance. We found that hA3G activity could have been responsible for only a small increase in mutations at known drug resistance sites and propose that concerns for increased resistance to other antiviral drugs should not prevent Vif from being considered a suitable target for development of new drugs.


Assuntos
Citidina Desaminase/metabolismo , Farmacorresistência Viral , HIV-1/genética , Mutação , Desaminase APOBEC-3G , Simulação por Computador , Pegada de DNA , Evolução Molecular , HIV-1/efeitos dos fármacos , HIV-1/fisiologia , Humanos , Modelos Genéticos , Reprodutibilidade dos Testes , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo
11.
Sci Rep ; 11(1): 13638, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34211037

RESUMO

Human cells respond to infection by SARS-CoV-2, the virus that causes COVID-19, by producing cytokines including type I and III interferons (IFNs) and proinflammatory factors such as IL6 and TNF. IFNs can limit SARS-CoV-2 replication but cytokine imbalance contributes to severe COVID-19. We studied how cells detect SARS-CoV-2 infection. We report that the cytosolic RNA sensor MDA5 was required for type I and III IFN induction in the lung cancer cell line Calu-3 upon SARS-CoV-2 infection. Type I and III IFN induction further required MAVS and IRF3. In contrast, induction of IL6 and TNF was independent of the MDA5-MAVS-IRF3 axis in this setting. We further found that SARS-CoV-2 infection inhibited the ability of cells to respond to IFNs. In sum, we identified MDA5 as a cellular sensor for SARS-CoV-2 infection that induced type I and III IFNs.


Assuntos
COVID-19/imunologia , Interferon Tipo I/imunologia , Helicase IFIH1 Induzida por Interferon/imunologia , Interferons/imunologia , SARS-CoV-2/imunologia , Linhagem Celular , Humanos , Imunidade Inata , RNA/imunologia , Interferon lambda
12.
Sci Adv ; 7(37): eabg7996, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34516768

RESUMO

There is an urgent requirement for safe and effective vaccines to prevent COVID-19. A concern for the development of new viral vaccines is the potential to induce vaccine-enhanced disease (VED). This was reported in several preclinical studies with both SARS-CoV-1 and MERS vaccines but has not been reported with SARS-CoV-2 vaccines. We have used ferrets and rhesus macaques challenged with SARS-CoV-2 to assess the potential for VED in animals vaccinated with formaldehyde-inactivated SARS-CoV-2 (FIV) formulated with Alhydrogel, compared to a negative control vaccine. We showed no evidence of enhanced disease in ferrets or rhesus macaques given FIV except for mild transient enhanced disease seen 7 days after infection in ferrets. This increased lung pathology was observed at day 7 but was resolved by day 15. We also demonstrate that formaldehyde treatment of SARS-CoV-2 reduces exposure of the spike receptor binding domain providing a mechanistic explanation for suboptimal immunity.

13.
J Virol ; 83(4): 1992-2003, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19036809

RESUMO

Human APOBEC3G (A3G) and APOBEC3F (A3F) inhibit the replication of Vif-deficient human immunodeficiency virus type 1 (HIV-1). HIV-1 Vif overcomes these host restriction factors by binding to them and inducing their degradation. Thus, the Vif-A3G and Vif-A3F interactions are attractive targets for antiviral drug development, as inhibiting these interactions could allow the host defense mechanism to control HIV-1 replication. Recently, it has been reported that amino acids 105 to 156 of A3G are involved in the interaction with Vif; however, to date, the region of A3F involved in Vif binding has not been identified. Using our previously reported Vif mutants that are capable of binding to only A3G (3G binder) or only A3F (3F binder), in conjunction with a series of A3G-A3F chimeras, we have now mapped the APOBEC3-Vif interaction domains. We found that the A3G domain that interacts with the Vif YRHHY region is located between amino acids 126 and 132 of A3G, which is consistent with the conclusions reported in previous studies. The A3F domain that interacts with the Vif DRMR region did not occur in the homologous domain but instead was located between amino acids 283 and 300 of A3F. These studies are the first to identify the A3F domain that interacts with the Vif DRMR region and show that distinct domains of A3G and A3F interact with different Vif regions. Pharmacological inhibition of either or both of these Vif-A3 interactions should prevent the degradation of the APOBEC3 proteins and could be used as a therapy against HIV-1.


Assuntos
Citidina Desaminase/metabolismo , Citosina Desaminase/metabolismo , HIV-1/fisiologia , Domínios e Motivos de Interação entre Proteínas , Mapeamento de Interação de Proteínas , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , Desaminase APOBEC-3G , Sequência de Aminoácidos , Linhagem Celular , Humanos , Dados de Sequência Molecular , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Ligação Proteica , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética
14.
Wellcome Open Res ; 5: 181, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33283055

RESUMO

Background: Laboratory diagnosis of SARS-CoV-2 infection (the cause of COVID-19) uses PCR to detect viral RNA (vRNA) in respiratory samples. SARS-CoV-2 RNA has also been detected in other sample types, but there is limited understanding of the clinical or laboratory significance of its detection in blood. Methods: We undertook a systematic literature review to assimilate the evidence for the frequency of vRNA in blood, and to identify associated clinical characteristics. We performed RT-PCR in serum samples from a UK clinical cohort of acute and convalescent COVID-19 cases (n=212), together with convalescent plasma samples collected by NHS Blood and Transplant (NHSBT) (n=462 additional samples). To determine whether PCR-positive blood samples could pose an infection risk, we attempted virus isolation from a subset of RNA-positive samples. Results: We identified 28 relevant studies, reporting SARS-CoV-2 RNA in 0-76% of blood samples; pooled estimate 10% (95%CI 5-18%). Among serum samples from our clinical cohort, 27/212 (12.7%) had SARS-CoV-2 RNA detected by RT-PCR. RNA detection occurred in samples up to day 20 post symptom onset, and was associated with more severe disease (multivariable odds ratio 7.5). Across all samples collected ≥28 days post symptom onset, 0/494 (0%, 95%CI 0-0.7%) had vRNA detected. Among our PCR-positive samples, cycle threshold (ct) values were high (range 33.5-44.8), suggesting low vRNA copy numbers. PCR-positive sera inoculated into cell culture did not produce any cytopathic effect or yield an increase in detectable SARS-CoV-2 RNA. Conclusions: vRNA was detectable at low viral loads in a minority of serum samples collected in acute infection, but was not associated with infectious SARS-CoV-2 (within the limitations of the assays used). This work helps to inform biosafety precautions for handling blood products from patients with current or previous COVID-19.

15.
Retrovirology ; 6: 16, 2009 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-19216784

RESUMO

BACKGROUND: Naturally occurring Vif variants that are unable to inhibit the host restriction factor APOBEC3G (A3G) have been isolated from infected individuals. A3G can potentially induce G-to-A hypermutation in these viruses, and hypermutation could contribute to genetic variation in HIV-1 populations through recombination between hypermutant and wild-type genomes. Thus, hypermutation could contribute to the generation of immune escape and drug resistant variants, but the genetic contribution of hypermutation to the viral evolutionary potential is poorly understood. In addition, the mechanisms by which these viruses persist in the host despite the presence of A3G remain unknown. RESULTS: To address these questions, we generated a replication-competent HIV-1 Vif mutant in which the A3G-binding residues of Vif, Y(40)RHHY(44), were substituted with five alanines. As expected, the mutant was severely defective in an A3G-expressing T cell line and exhibited a significant delay in replication kinetics. Analysis of viral DNA showed the expected high level of G-to-A hypermutation; however, we found substantially reduced levels of G-to-A hypermutation in intracellular viral RNA (cRNA), and the levels of G-to-A mutations in virion RNA (vRNA) were even further reduced. The frequencies of hypermutation in DNA, cRNA, and vRNA were 0.73%, 0.12%, and 0.05% of the nucleotides sequenced, indicating a gradient of hypermutation. Additionally, genomes containing start codon mutations and early termination codons within gag were isolated from the vRNA. CONCLUSION: These results suggest that sublethal levels of hypermutation coupled with purifying selection at multiple steps during the early phase of viral replication lead to the packaging of largely unmutated genomes, providing a mechanism by which mutant Vif variants can persist in infected individuals. The persistence of genomes containing mutated gag genes despite this selection pressure indicates that dual infection and complementation can result in the packaging of hypermutated genomes which, through recombination with wild-type genomes, could increase viral genetic variation and contribute to evolution.


Assuntos
Citidina Desaminase/metabolismo , DNA Viral/genética , HIV-1/fisiologia , Mutação/genética , RNA Viral/genética , Vírion/genética , Replicação Viral/fisiologia , Desaminase APOBEC-3G , Linhagem Celular , Citidina Desaminase/genética , Genes gag/genética , Genes vif/genética , Células HeLa , Humanos
17.
World J Pediatr Congenit Heart Surg ; 8(4): 427-434, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28696880

RESUMO

OBJECTIVE: To evaluate the performance of the Pediatric Risk of Mortality 3 (PRISM-3) score in critically ill children with heart disease. METHODS: Patients <18 years of age admitted with cardiac diagnoses (cardiac medical and cardiac surgical) to one of the participating pediatric intensive care units in the Virtual Pediatric Systems, LLC, database were included. Performance of PRISM-3 was evaluated with discrimination and calibration measures among both cardiac surgical and cardiac medical patients. RESULTS: The study population consisted of 87,993 patients, of which 49% were cardiac medical patients (n = 43,545) and 51% were cardiac surgical patients (n = 44,448). The ability of PRISM-3 to distinguish survivors from nonsurvivors was acceptable for the entire cohort (c-statistic 0.86). However, PRISM-3 did not perform as well when stratified by varied severity of illness categories. Pediatric Risk of Mortality 3 underpredicted mortality among patients with lower severity of illness categories (quintiles 1-4) whereas it overpredicted mortality among patients with greatest severity of illness category (fifth quintile). When stratified by Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery (STS-EACTS) categories, PRISM-3 overpredicted mortality among the STS-EACTS mortality categories 1, 2, and 3 and underpredicted mortality among the STS-EACTS mortality categories 4 and 5. Pediatric Risk of Mortality 3 overpredicted mortality among centers with high cardiac surgery volume whereas it underpredicted mortality among centers with low cardiac surgery volume. CONCLUSION: Data from this large multicenter study do not support the use of PRISM-3 in cardiac surgical or cardiac medical patients. In this study, the ability of PRISM-3 to distinguish survivors from nonsurvivors was fair at best, and the accuracy with which it predicted death was poor.


Assuntos
Estado Terminal , Cardiopatias/mortalidade , Unidades de Terapia Intensiva Pediátrica/estatística & dados numéricos , Criança , Pré-Escolar , Bases de Dados Factuais , Feminino , Cardiopatias/diagnóstico , Mortalidade Hospitalar/tendências , Humanos , Lactente , Masculino , Estudos Retrospectivos , Índice de Gravidade de Doença , Taxa de Sobrevida/tendências , Estados Unidos/epidemiologia
18.
Cell Rep ; 18(6): 1473-1483, 2017 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-28178524

RESUMO

HIV-1 disseminates to diverse tissues and establishes long-lived viral reservoirs. These reservoirs include the CNS, in which macrophage-lineage cells, and as suggested by many studies, astrocytes, may be infected. Here, we have investigated astrocyte infection by HIV-1. We confirm that astrocytes trap and internalize HIV-1 particles for subsequent release but find no evidence that these particles infect the cell. Astrocyte infection was not observed by cell-free or cell-to-cell routes using diverse approaches, including luciferase and GFP reporter viruses, fixed and live-cell fusion assays, multispectral flow cytometry, and super-resolution imaging. By contrast, we observed intimate interactions between HIV-1-infected macrophages and astrocytes leading to signals that might be mistaken for astrocyte infection using less stringent approaches. These results have implications for HIV-1 infection of the CNS, viral reservoir formation, and antiretroviral therapy.


Assuntos
Astrócitos/virologia , Infecções por HIV/virologia , HIV-1/patogenicidade , Macrófagos/virologia , Astrócitos/metabolismo , Fusão Celular/métodos , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/virologia , Proteínas de Fluorescência Verde/metabolismo , Infecções por HIV/metabolismo , Humanos , Luciferases/metabolismo , Macrófagos/metabolismo
19.
J Drug Deliv ; 2015: 686598, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26664749

RESUMO

Background. The ability of safety technologies to decrease errors, harm, and risk to patients has yet to be demonstrated consistently. Objective. To compare discrepancies between medication and intravenous fluid (IVF) orders and bedside infusion pump settings within a pediatric intensive care unit (PICU) before and after implementation of an interface between computerized physician order entry (CPOE) and pharmacy systems. Methods. Within a 72-bed PICU, medication and IVF orders in the CPOE system and bedside infusion pump settings were collected. Rates of discrepancy were calculated and categorized by type. Results were compared to a study conducted prior to interface implementation. Expansion of PICU also occurred between study periods. Results. Of 455 observations, discrepancy rate decreased for IVF (p = 0.01) compared to previous study. Overall discrepancy rate for medications was unchanged; however, medications infusing without an order decreased (p < 0.01), and orders without corresponding infusion increased (p < 0.05). Conclusions. Following implementation of an interface between CPOE and pharmacy systems, fewer discrepancies between IVF orders and infusion pump settings were observed. Discrepancies for medications did not change, and some types of discrepancies increased. In addition to interface implementation, changes in healthcare delivery and workflow related to ICU expansion contributed to observed changes.

20.
Clin Vaccine Immunol ; 22(9): 1004-12, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26135973

RESUMO

The continued discovery and development of adjuvants for vaccine formulation are important to safely increase potency and/or reduce the antigen doses of existing vaccines and tailor the adaptive immune response to newly developed vaccines. Adjuplex is a novel adjuvant platform based on a purified lecithin and carbomer homopolymer. Here, we analyzed the adjuvant activity of Adjuplex in mice for the soluble hemagglutinin (HA) glycoprotein of influenza A virus. The titration of Adjuplex revealed an optimal dose of 1% for immunogenicity, eliciting high titers of HA-specific IgG but inducing no significant weight loss. At this dose, Adjuplex completely protected mice from an otherwise lethal influenza virus challenge and was at least as effective as the adjuvants monophosphoryl lipid A (MPL) and alum in preventing disease. Adjuplex elicited balanced Th1-/Th2-type immune responses with accompanying cytokines and triggered antigen-specific CD8(+) T-cell proliferation. The use of the peritoneal inflammation model revealed that Adjuplex recruited dendritic cells (DCs), monocytes, and neutrophils in the context of innate cytokine and chemokine secretion. Adjuplex neither triggered classical maturation of DCs nor activated a pathogen recognition receptor (PRR)-expressing NF-κB reporter cell line, suggesting a mechanism of action different from that reported for classical pathogen-associated molecular pattern (PAMP)-activated innate immunity. Taken together, these data reveal Adjuplex to be a potent and well-tolerated adjuvant with application for subunit vaccines.


Assuntos
Imunidade Adaptativa , Adjuvantes Imunológicos , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A Subtipo H1N1/imunologia , Vacinas contra Influenza/imunologia , Infecções por Orthomyxoviridae/prevenção & controle , Resinas Acrílicas , Adjuvantes Imunológicos/administração & dosagem , Animais , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/imunologia , Linfócitos B/imunologia , Linfócitos T CD8-Positivos/imunologia , Citocinas/imunologia , Citocinas/metabolismo , Células Dendríticas/imunologia , Vacinas contra Influenza/administração & dosagem , Lecitinas/imunologia , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae/imunologia , Moléculas com Motivos Associados a Patógenos , Equilíbrio Th1-Th2 , Vacinação
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