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Front Immunol ; 11: 1836, 2020.
Article in English | MEDLINE | ID: covidwho-1389162


Examining CD8+ and CD4+ T cell responses after primary Yellow Fever vaccination in a cohort of 210 volunteers, we have identified and tetramer-validated 92 CD8+ and 50 CD4+ T cell epitopes, many inducing strong and prevalent (i.e., immunodominant) T cell responses. Restricted by 40 and 14 HLA-class I and II allotypes, respectively, these responses have wide population coverage and might be of considerable academic, diagnostic and therapeutic interest. The broad coverage of epitopes and HLA overcame the otherwise confounding effects of HLA diversity and non-HLA background providing the first evidence of T cell immunodomination in humans. Also, double-staining of CD4+ T cells with tetramers representing the same HLA-binding core, albeit with different flanking regions, demonstrated an extensive diversification of the specificities of many CD4+ T cell responses. We suggest that this could reduce the risk of pathogen escape, and that multi-tetramer staining is required to reveal the true magnitude and diversity of CD4+ T cell responses. Our T cell epitope discovery approach uses a combination of (1) overlapping peptides representing the entire Yellow Fever virus proteome to search for peptides containing CD4+ and/or CD8+ T cell epitopes, (2) predictors of peptide-HLA binding to suggest epitopes and their restricting HLA allotypes, (3) generation of peptide-HLA tetramers to identify T cell epitopes, and (4) analysis of ex vivo T cell responses to validate the same. This approach is systematic, exhaustive, and can be done in any individual of any HLA haplotype. It is all-inclusive in the sense that it includes all protein antigens and peptide epitopes, and encompasses both CD4+ and CD8+ T cell epitopes. It is efficient and, importantly, reduces the false discovery rate. The unbiased nature of the T cell epitope discovery approach presented here should support the refinement of future peptide-HLA class I and II predictors and tetramer technologies, which eventually should cover all HLA class I and II isotypes. We believe that future investigations of emerging pathogens (e.g., SARS-CoV-2) should include population-wide T cell epitope discovery using blood samples from patients, convalescents and/or long-term survivors, who might all hold important information on T cell epitopes and responses.

CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Epitopes, T-Lymphocyte/immunology , Vaccination , Yellow Fever Vaccine/immunology , Yellow Fever/prevention & control , Yellow fever virus/immunology , Betacoronavirus/immunology , COVID-19 , Cohort Studies , Coronavirus Infections/prevention & control , Coronavirus Infections/virology , Healthy Volunteers , Histocompatibility Antigens Class I/immunology , Histocompatibility Antigens Class II/immunology , Humans , Immunogenicity, Vaccine , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/virology , SARS-CoV-2 , Yellow Fever/virology
Front Immunol ; 11: 575074, 2020.
Article in English | MEDLINE | ID: covidwho-1256374


Combined cellular and humoral host immune response determine the clinical course of a viral infection and effectiveness of vaccination, but currently the cellular immune response cannot be measured on simple blood samples. As functional activity of immune cells is determined by coordinated activity of signaling pathways, we developed mRNA-based JAK-STAT signaling pathway activity assays to quantitatively measure the cellular immune response on Affymetrix expression microarray data of various types of blood samples from virally infected patients (influenza, RSV, dengue, yellow fever, rotavirus) or vaccinated individuals, and to determine vaccine immunogenicity. JAK-STAT1/2 pathway activity was increased in blood samples of patients with viral, but not bacterial, infection and was higher in influenza compared to RSV-infected patients, reflecting known differences in immunogenicity. High JAK-STAT3 pathway activity was associated with more severe RSV infection. In contrast to inactivated influenza virus vaccine, live yellow fever vaccine did induce JAK-STAT1/2 pathway activity in blood samples, indicating superior immunogenicity. Normal (healthy) JAK-STAT1/2 pathway activity was established, enabling assay interpretation without the need for a reference sample. The JAK-STAT pathway assays enable measurement of cellular immune response for prognosis, therapy stratification, vaccine development, and clinical testing.

Dengue Virus/immunology , Immunity, Cellular , Orthomyxoviridae/immunology , Respiratory Syncytial Virus, Human/immunology , Rotavirus/immunology , Viral Vaccines/therapeutic use , Virus Diseases/immunology , Yellow fever virus/immunology , Biomarkers/blood , Dengue/blood , Dengue/immunology , Dengue/prevention & control , Dengue/virology , Dengue Vaccines/therapeutic use , Dengue Virus/pathogenicity , Diagnosis, Differential , Host-Pathogen Interactions , Humans , Immunogenicity, Vaccine , Influenza Vaccines/therapeutic use , Influenza, Human/blood , Influenza, Human/immunology , Influenza, Human/prevention & control , Influenza, Human/virology , Oligonucleotide Array Sequence Analysis , Orthomyxoviridae/pathogenicity , Predictive Value of Tests , RNA, Messenger/blood , RNA, Messenger/genetics , Respiratory Syncytial Virus Infections/blood , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Virus Infections/prevention & control , Respiratory Syncytial Virus Infections/virology , Respiratory Syncytial Virus, Human/pathogenicity , Rotavirus/pathogenicity , Rotavirus Infections/blood , Rotavirus Infections/immunology , Rotavirus Infections/prevention & control , Rotavirus Infections/virology , Rotavirus Vaccines , Signal Transduction/genetics , Virus Diseases/blood , Virus Diseases/prevention & control , Virus Diseases/virology , Yellow Fever/blood , Yellow Fever/immunology , Yellow Fever/prevention & control , Yellow Fever/virology , Yellow Fever Vaccine/therapeutic use , Yellow fever virus/pathogenicity
N Engl J Med ; 383(5): 452-459, 2020 07 30.
Article in English | MEDLINE | ID: covidwho-692294


BACKGROUND: Insufficient vaccine doses and the lack of therapeutic agents for yellow fever put global health at risk, should this virus emerge from sub-Saharan Africa and South America. METHODS: In phase 1a of this clinical trial, we assessed the safety, side-effect profile, and pharmacokinetics of TY014, a fully human IgG1 anti-yellow fever virus monoclonal antibody. In a double-blind, phase 1b clinical trial, we assessed the efficacy of TY014, as compared with placebo, in abrogating viremia related to the administration of live yellow fever vaccine (YF17D-204; Stamaril). The primary safety outcomes were adverse events reported 1 hour after the infusion and throughout the trial. The primary efficacy outcome was the dose of TY014 at which 100% of the participants tested negative for viremia within 48 hours after infusion. RESULTS: A total of 27 healthy participants were enrolled in phase 1a, and 10 participants in phase 1b. During phase 1a, TY014 dose escalation to a maximum of 20 mg per kilogram of body weight occurred in 22 participants. During phases 1a and 1b, adverse events within 1 hour after infusion occurred in 1 of 27 participants who received TY014 and in none of the 10 participants who received placebo. At least one adverse event occurred during the trial in 22 participants who received TY014 and in 8 who received placebo. The mean half-life of TY014 was approximately 12.8 days. At 48 hours after the infusion, none of the 5 participants who received the starting dose of TY014 of 2 mg per kilogram had detectable YF17D-204 viremia; these participants remained aviremic throughout the trial. Viremia was observed at 48 hours after the infusion in 2 of 5 participants who received placebo and at 72 hours in 2 more placebo recipients. Symptoms associated with yellow fever vaccine were less frequent in the TY014 group than in the placebo group. CONCLUSIONS: This phase 1 trial of TY014 did not identify worrisome safety signals and suggested potential clinical benefit, which requires further assessment in a phase 2 trial. (Funded by Tysana; number, NCT03776786.).

Antibodies, Monoclonal, Humanized/administration & dosage , Yellow Fever Vaccine , Yellow Fever/drug therapy , Yellow fever virus/immunology , Adult , Antibodies, Monoclonal, Humanized/adverse effects , Antibodies, Monoclonal, Humanized/pharmacokinetics , Dose-Response Relationship, Drug , Double-Blind Method , Half-Life , Humans , Kaplan-Meier Estimate , Viremia/drug therapy , Yellow Fever/virology , Yellow fever virus/drug effects