IntroductionAlterations in the gut immune system have been implicated in various diseases.The challenge of obtaining gut tissues from healthy individuals, commonly performed via surgical explants, has limited the number of studies describing the phenotype and function of gut-derived immune cells in health. MethodsHere, by means of recto-sigmoid colon biopsies obtained during routine care (colon cancer screening in healthy adults), the phenotype and function of immune cells present in the gut were described and compared to those found in blood.ResultsThe proportion of CD4+, CD8+, MAIT, γδ+ T, and NK cells phenotype, expression of integrins, and ability to produce cytokine in response to stimulation with PMA and ionomycin. T cells in the gut were found to predominantly have a memory phenotype as compared to T cells in blood where a naïve phenotype predominates. Recto-sigmoid mononuclear cells also had higher PD-1 and Ki67 expression. Furthermore, integrin expression and cytokine production varied by cell type and location in blood vs. gut.DiscussionThese findings demonstrate the differences in functionality of these cells when compared to their blood counterparts and validate previous studies on phenotype within gut-derived immune cells in humans (where cells have been obtained through surgical means). This study suggests that recto-sigmoid biopsies collected during colonoscopy can be a reliable yet more accessible sampling method for follow up of alterations of gut derived immune cells in clinical settings.

Abstract Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, which are immunogenic targets in a CMV-based GBM immunotherapeutic. First-recurrent GBM patients with KPS³70 received VBI-1901 (a gB/pp65 enveloped virus-like particle [eVLP]) adjuvanted with GM-CSF intradermally (NCT03382977). Patients received VBI-1901 q4w, with serologic immune-monitoring q2w after each vaccination and surveillance brain MRI scans q6w. Among 16 patients treated with the highest (10µg dose) of VBI-1901, the mOS was 12.9 months with a 12-month OS rate of 62.5%. T cell-mediated collagen remodeling is necessary for T cell migration and activity. The peripheral C4G biomarker targets granzyme-B-cleaved type IV collagen, which is associated with T cell infiltration and has previously been shown to potentially identify recurrent GBM patients responding to nivolumab and bevacizumab. Here, C4G was measured in available plasma samples from patients with progressive disease (PD) (n = 9), stable disease (SD) (n = 5) or partial tumor responses (PR) (n = 2) prior to (baseline) and after (cycle 1-4) treatment with VBI-1901. Although numerically lower in patients with PD, there were no differences in baseline levels of C4G among the groups. However, there were statistically significant increases in C4G levels in the 2 patients with PR both after 1st/2nd doses (p = 0.0324) and after 3rd/4th doses (p = 0.0027) of treatment (1st/2nd doses; PD: 7.6ng/mL, SD: 10.0ng/mL, PR: 21.0ng/mL. 3rd/4th doses; PD: 6.1ng/mL, SD: 8.5ng/mL, PR: 16.8ng/mL). On-going analyses are evaluating additional peripheral markers of tumor microenvironment (TME) remodeling. Evaluating the balance of immune infiltration vs. tumor cell growth in patients with brain tumors is challenging and these data suggest a means of assessing this dynamic using a peripheral biomarker. These data may be particularly useful in discerning pseudoprogression associated with T cell infiltration from tumor progression.

Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, which are immunogenic targets in a CMV-based GBM immunotherapeutic. First-recurrent GBM patients with KPS³70 received VBI-1901 (a gB/pp65 enveloped virus-like particle [eVLP]) adjuvanted with GM-CSF intradermally (NCT03382977). Patients received VBI-1901 q4w, with serologic immune-monitoring q2w after each vaccination and surveillance brain MRI scans q6w. Among 16 patients treated with the highest (10µg dose) of VBI-1901, the mOS was 12.9 months with a 12-month OS rate of 62.5%. T cell-mediated collagen remodeling is necessary for T cell migration and activity. The peripheral C4G biomarker targets granzyme-B-cleaved type IV collagen, which is associated with T cell infiltration and has previously been shown to potentially identify recurrent GBM patients responding to nivolumab and bevacizumab. Here, C4G was measured in available plasma samples from patients with progressive disease (PD) (n = 9), stable disease (SD) (n = 5) or partial tumor responses (PR) (n = 2) prior to (baseline) and after (cycle 1-4) treatment with VBI-1901. Although numerically lower in patients with PD, there were no differences in baseline levels of C4G among the groups. However, there were statistically significant increases in C4G levels in the 2 patients with PR both after 1st/2nd doses (p = 0.0324) and after 3rd/4th doses (p = 0.0027) of treatment (1st/2nd doses; PD: 7.6ng/mL, SD: 10.0ng/mL, PR: 21.0ng/mL. 3rd/4th doses; PD: 6.1ng/mL, SD: 8.5ng/mL, PR: 16.8ng/mL). On-going analyses are evaluating additional peripheral markers of tumor microenvironment (TME) remodeling. Evaluating the balance of immune infiltration vs. tumor cell growth in patients with brain tumors is challenging and these data suggest a means of assessing this dynamic using a peripheral biomarker. These data may be particularly useful in discerning pseudoprogression associated with T cell infiltration from tumor progression.

Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, which are immunogenic targets in a CMV-based GBM immunotherapeutic. First-recurrent GBM patients were enrolled, with Karnofsky Performance Status of at least 70, to receive VBI-1901 (a gB/pp65 enveloped virus-like particle [eVLP]) adjuvanted with GM-CSF and given intradermally (NCT03382977). Patients were vaccinated with VBI-1901 every 4 weeks, with serologic immune-monitoring 2 weeks after each vaccination and surveillance brain MRI scans every 6 weeks. Sixteen patients (8 women, 8 men) with a median age of 55 (33-67 yrs) were enrolled into the GM-CSF arm. Seven tumor responses, including two durable partial responses, were observed which led to an 18-month OS rate of 25% and mOS of 56 weeks. Detailed immunological testing was performed to identify potential correlations at baseline and after treatment between biomarkers and tumor responses. Analyses included class I and II HLA typing, modulation of plasma cytokine and chemokine responses, boosting of CMV-specific antibody and IFN-g ELISPOT responses, and modulation of CMV-specific CD4 Tem cells, of which only differential trafficking of the CD4 Tem cells appears to distinguish patients with tumor responses from those with tumor progression. Single cell, RNAseq is underway in an attempt to understand mechanistic differences in these immune cell populations in Tumor Responders vs. Non-Responders. The U.S. FDA granted Fast Track Designation to VBI-1901 adjuvanted with GM-CSF in first-recurrent GBM patients, and an expansion of the ongoing trial with this formulation in this patient population, with the addition of randomization with a contemporaneous control arm, is anticipated to begin in Q3 2022.

2014 Background: Cytomegalovirus (CMV) antigens have been reported in over 90% of GBMs. CD4+ and CD8+ T cells are most frequently directed against the gB and pp65 antigens, respectively, which are immunogenic targets in a CMV-based GBM immunotherapeutic. Methods: A total of 20 first-recurrent GBM patients were enrolled, with Karnofsky Performance Status of at least 70, across 2 arms of the Phase IIa extension phase to receive VBI-1901 (a gB/pp65 enveloped virus-like particle [eVLP]) adjuvanted with either GM-CSF (given intradermally) or AS01B (given intramuscularly) (NCT03382977). Patients were vaccinated with VBI-1901 every 4 weeks, with serologic immune-monitoring 2 weeks after each vaccination and surveillance brain MRI scans every 6 weeks. Results: 10 patients (6 women, 4 men) with a median age of 58 (33-67 yrs) were enrolled into the GM-CSF arm and 10 patients (3 women, 7 men) with a median age of 65 (40-67) enrolled into the AS01B arm. The 12-month OS rates for the GM-CSF and AS01B arms were 60% and 70%, respectively; the 18-month OS rate for the GM-CSF arm was 30%, and for the AS01B arm is expected to be 30%-40% (data has not yet matured). Two durable partial responses (locally determined by RANO) have been observed in the GM-CSF arm, with one patient progression-free and on protocol after 2 years with a tumor size reduction of 93% relative to start of treatment. Immunological analyses demonstrate that prolonged, monthly dosing with VBI-1901 does not lead to immunological tolerance. Dynamic boosting and loss in the peripheral blood of CMV-specific CD4 Tem cells after treatment with VBI-1901 formulated with GM-CSF may correlate with tumor responses. Conclusions: The U.S. FDA granted Fast Track Designation to VBI-1901 adjuvanted with GM-CSF in first-recurrent GBM patients, and an expansion of the ongoing trial with this formulation in this patient population, with the addition of randomization with a contemporaneous control arm, is anticipated to begin in H1 2022. Acknowledgement: GlaxoSmithKline Biologicals SA provided the AS01B adjuvant used in this study. Clinical trial information: NCT03382977.

Abstract Soluble cytokine receptors can influence immune responses by modulating the biological functions of their respective ligands. These effects can be either agonistic or antagonistic and a number of soluble cytokine receptors have been shown to play critical roles in both maintenance of health and disease pathogenesis. Soluble IL-7Ra (sCD127) is one such example. With its impact on the IL-7/CD127 pathway, which is fundamental for the development and homeostasis of T cells, the role of sCD127 in health and disease has been extensively studied in recent years. Within this review, the role of sCD127 in maintaining host immune function is presented. Next, by addressing genetic factors affecting sCD127 expression and the associated levels of sCD127 production, the roles of sCD127 in autoimmune disease, infections and cancer are described. Finally, advances in the field of soluble cytokine therapy and the potential for sCD127 as a biomarker and therapeutic agent are discussed.

Development of efficacious single dose vaccines would substantially aid efforts to stop the uncontrolled spread of the COVID-19 pandemic. We evaluated enveloped virus-like particles (eVLPs) expressing various forms of the SARS-CoV-2 spike protein and several adjuvants in an effort to identify a COVID-19 vaccine candidate efficacious after a single dose. The eVLPs expressing a modified prefusion form of SARS-CoV-2 spike protein were selected as they induced the highest antibody binding titers and neutralizing activity after a single injection in mice. Formulation of SARS-CoV-2 S eVLPs with aluminum phosphate resulted in balanced induction of IgG2 and IgG1 isotypes and antibody binding and neutralization titers were undiminished for more than 3 months after a single immunization. A single dose of this candidate, VBI-2902a (prefusion S eVLPs formulated with aluminum phosphate), protected Syrian golden hamsters from challenge with SARS-CoV-2 and supports the on-going clinical evaluation of VBI-2902a as a potential single dose vaccine against COVID-19. Highlights VBI-2902a is a VLP-based vaccine candidate against SARS-COV-2 VBI-2902a contains VLPs pseudotyped with a modified prefusion SARS-COV-2 S in Alum. VBI-2902a induces robust neutralization antibody response against SARS-COV-2 S VBI-2902a protects hamsters from SARS-CoV-2 induced lung inflammation A single dose of VBI-2902a provides protective benefit in hamsters

Rapid emergence of SARS-CoV-2 variants is a constant threat and a major hurdle to reach heard immunity. We produced VBI-2905a, an enveloped virus-like particle (eVLP)-based vaccine candidate expressing prefusion spike protein from the Beta variant that contains several escape mutations. VBI-2905a protected hamsters against infection with a Beta variant virus and induced high levels of neutralizing antibodies against Beta RBD. In a heterologous vaccination regimen, a single injection of VBI-2905a in animals previously immunized with VBI-2902, a vaccine candidate expressing S from ancestral SARS-CoV-2, hamsters were equally protected against Beta variant infection. As an alternate strategy to broaden immunity, we produced a trivalent vaccine expressing the prefusion spike protein from SARS-CoV-2 together with unmodifed S from SARS-CoV-1 and MERS-CoV. Relative to immunity induced against the ancestral strain, the trivalent vaccine VBI-2901a induced higher and more consistent antibody binding and neutralizing responses against a panel of variants including Beta, Delta, Kappa, and Lambda, with evidence for broadening of immunity rather than just boosting cross-reactive antibodies.

Abstract Numerous independent laboratories using several techniques have demonstrated cytomegalovirus (CMV) antigens in over 90% of glioblastoma (GBM) tumors. We initiated a phase I/IIA multicenter study designed to demonstrate safety and determine the most immunogenic dose of an enveloped virus-like particle (eVLP) vaccine expressing the CMV gB and pp65 antigens for treatment of recurrent GBM patients. In Part A of the trial, 6 patients in each of 3 different antigen dose cohorts were vaccinated monthly and followed until tumor progression, with PBMCs collected 2 weeks after each vaccination. Surprisingly, only 7/18 patients enrolled in Part A of the trial had baseline CMV-specific antibody (Ab) titers. This was unexpected given the documented high prevalence of CMV antigens in GBM tumor samples as well as epidemiological data demonstrating much higher CMV Ab seropositive rates in otherwise healthy individuals of a comparable age. In the low dose cohort, 4/6 patients had baseline CMV Ab titers. Of these 4 patients,vaccination boosted strong T cell responses in 2 patients (based on IFN-γ ELISPOT against CMV gB and pp65 antigens). Vaccination did not boost T-cell responses in the CMV Ab-negative patients. In the intermediate dose cohort, among 4 evaluable patients, T cell responses were robustly boosted in the only patient with a baseline CMV Ab titer. In marked contrast, the T-cell responses in the high dose cohort were boosted in 3/5 evaluable patients, all of which were CMV Ab seronegative at baseline. Moreover, the T-cell responses correlated with tumor responses (stable disease based on 2 or more stable MRI scans) as well as improved PFS and 6 month OS relative to vaccine non-responders. To further understand the apparent disconnect between baseline CMV Ab titers and vaccine-mediated impact on tumor and clinical responses, we developed a more sensitive flow cytometry-based assay which evaluated proliferating (Ki-67-positive) gB- and pp65-specific T cells within naïve, central memory (CD45RA-CCR7+) or effector memory (CD45RA-CCR7-) subsets. Among 2/3 tested vaccine responders evaluated thus far in the high dose cohort that were CMV Ab negative at baseline, high frequencies of effector memory cells (~2% total CD3+CD4+ T cells) against both the CMV pp65 and gB antigens were detected at baseline. Collectively, these data suggest that CMV-specific immune dysregulation exists in a substantial number of rGBM patients, which can be overcome with the appropriate dose of a CMV vaccine immunotherapeutic. Importantly, vaccine-mediated boosting of CMV immunity correlates with improved tumor response and clinical outcomes and warrants further confirmation. Citation Format: Tamara Berthoud, Felicia Deonarine, Spenser Ng Cheong Chung, Catalina Soare, Francisco Diaz-Mitoma, David E. Anderson. CMV-specific immuno-dysregulation in recurrent glioblastoma patients can be overcome with therapeutic vaccination which is associated with tumor response and overall survival benefits in a Phase I/IIA study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6538.

The IL‐7 receptor specific α chain, CD127, can be expressed both as a membrane‐associated (mCD127) and a soluble form (sCD127), however, the mechanisms involved in their regulation remain to be defined. We first demonstrated in primary human CD8 + T cells that IL‐7‐induced downregulation of mCD127 expression is dependent on JAK and PI3K signaling, whereas IL‐7‐induced sCD127 release is also mediated by STAT5. Following stimulation with IL‐7, expression of alternatively spliced variants of the CD127 gene, sCD127 mRNA, is reduced, but to a lesser degree than the full‐length gene. Evaluation of the role of proteases revealed that MMP‐9 was involved in sCD127 release, without affecting the expression of mCD127, suggesting it does not induce direct shedding from the cell surface. Since defects in the IL‐7/CD127 pathway occur in various diseases, including HIV, we evaluated CD8 + T cells derived from HAART‐treated HIV‐infected individuals and found that IL‐7‐induced (1) downregulation of mCD127, (2) release of sCD127, and (3) expression of the sCD127 mRNA were all impaired. Expression of mCD127 and sCD127 is, therefore, regulated by distinct, but overlapping, mechanisms and their impairment in HIV infection contributes to our understanding of the CD8 + T cell dysfunction that persists despite effective antiretroviral therapy.

Objectives: Th17 cells are key regulators of functional immunity in mucosal tissues, including the gut-associated lymphoid tissue (GALT), an important site of immune impairment in HIV infection. During HIV infection, Th17 cells are lost in large numbers from the GALT. Despite the recovery of peripheral CD4(+) T cells that accompanies suppression of viral replication with HAART, Th17 cells in GALT are not completely restored. IL-7 is essential for the survival and proliferation of T cells, but its signaling through its receptor IL-7R alpha (CD127), is impaired in CD8(+) T cells and thymocytes during HIV infection. We set out to determine if decreased CD127 expression or impaired CD127 signaling may be the cause of Th17 impairment in HAART-controlled HIV infection. Design: Healthy and HIV thorn donors on HAART were selected for this study of Th17 cell function in HIV. Methods: Peripheral CD4(+) T cells and Th17 cells were isolated using magnetic beads, then stimulated with IL-7. CD127 expression and the phosphorylation of signaling molecules was determined using flow cytometry. Proliferation was determined with a CFSE dilution assay. Results: CD127 was not decreased on Th17 cells from HAART-controlled HIV thorn individuals, in fact, the percentage of Th17 cells that express CD127 was increased in treated HIV thorn individuals. Furthermore, Th17 cells from HAART-controlled individuals, have normal IL-7-induced STAT5 and Bcl-2 responses, but vastly decreased proliferative responses. Conclusion: This reduced IL-7 responsiveness may explain the lack of Th17 cell recovery and ongoing systemic immune activation that persists despite well treated HIV infection. Copyright (C) 2019 Wolters Kluwer Health, Inc. All rights reserved.

BACKGROUND:Increased susceptibility to malaria during pregnancy is not completely understood. Cellular immune responses mediate both pathology and immunity but the effector responses involved in these processes have not been fully characterized. Maternal and fetal cytokine and chemokine responses to malaria at delivery, and their association with pregnancy and childhood outcomes, were investigated in 174 samples from a mother and child cohort from Mozambique. Peripheral and cord mononuclear cells were stimulated with Plasmodium falciparum lysate and secretion of IL-12p70, IFN-γ, IL-2, IL-10, IL-8, IL-6, IL-4, IL-5, IL-1β, TNF, TNF-β was quantified in culture supernatants by multiplex flow cytometry while cellular mRNA expression of IFN-γ, TNF, IL-2, IL-4, IL-6, IL-10 and IL-13 was measured by quantitative PCR. RESULTS:Higher concentrations of IL-6 and IL-1β were associated with a reduced risk of P. falciparum infection in pregnant women (p < 0.049). Pro-inflammatory cytokines IL-6, IL-1β and TNF strongly correlated among themselves (ρ > 0.5, p < 0.001). Higher production of IL-1β was significantly associated with congenital malaria (p < 0.046) and excessive TNF was associated with peripheral infection and placental lesions (p < 0.044). CONCLUSIONS:Complex network of immuno-pathological cytokine mechanisms in the placental and utero environments showed a potential trade-off between positive and negative effects on mother and newborn susceptibility to infection.

Background The effect of timing of exposure to first Plasmodium falciparum infections during early childhood on the induction of innate and adaptive cytokine responses and their contribution to the development of clinical malaria immunity is not well established. Methods As part of a double-blind, randomized, placebo-controlled trial in Mozambique using monthly chemoprophylaxis with sulfadoxine-pyrimethamine plus artesunate to selectively control timing of malaria exposure during infancy, peripheral blood mononuclear cells collected from participants at age 2.5, 5.5, 10.5, 15, and 24 months were stimulated ex vivo with parasite schizont and erythrocyte lysates. Cytokine messenger RNA expressed in cell pellets and proteins secreted in supernatants were quantified by reverse-transcription quantitative polymerase chain reaction and multiplex flow cytometry, respectively. Children were followed up for clinical malaria from birth until 4 years of age. Results Higher proinflammatory (interleukin [IL] 1, IL-6, tumor necrosis factor) and regulatory (IL-10) cytokine concentrations during the second year of life were associated with reduced incidence of clinical malaria up to 4 years of age, adjusting by chemoprophylaxis and prior malaria exposure. Significantly lower concentrations of antigen-specific T-helper 1 (IL-2, IL-12, interferon-gamma) and T-helper 2 (IL-4, IL-5) cytokines by 2 years of age were measured in children undergoing chemoprophylaxis compared to children receiving placebo (P < .03). Conclusions Selective chemoprophylaxis altering early natural exposure to malaria blood stage antigens during infancy had a significant effect on T-helper lymphocyte cytokine production >1 year later. Importantly, a balanced proinflammatory and anti-inflammatory cytokine signature, probably by innate cells, around age 2 years was associated with protective clinical immunity during childhood.

Objectives HIV infection causes a profound depletion of gut derived Th17 cells, contributing to loss of mucosal barrier function and an increase in microbial translocation, thus driving systemic immune activation. Despite normalization of circulating CD4+ T cell counts with highly active antiretroviral therapy (HAART), Th17 frequency and function often remain impaired. Given the importance of interleukin (IL)-23 in the generation and stabilization of Th17 cells we hypothesized that impaired IL-23 signaling causes persistent Th17 dysfunction in HIV infection. Methods The effects of in vitro HIV infection on responses to IL-23 in Th17 cells were examined. These included the production of IL-17, phosphorylated STAT3 (pSTAT3) and the transcription of retinoic acid orphan receptor C (RORC) gene. Blood derived Th17 cells from untreated and HAART-treated HIV-infected individuals were also examined for the IL-23 induced production of phosphorylated STAT3 (pSTAT3) and the expression of the IL-23 receptors. Results In vitro HIV infection significantly inhibited IL-17 production and IL-23 induced pSTAT3 while expression of RORC RNA was unaffected. Th17 cells isolated from untreated and HAART-treated HIV-infected individuals showed complete loss of IL-23 induced pSTAT3 without a decrease in the expression of the IL-23 receptors. Conclusions This study is the first to demonstrate an effect of HIV on the IL-23 signaling pathway in Th17 cells. We show that in vitro and in vivo HIV infection results in impaired IL-23 signaling which is not reversed by HAART nor is it a result of reduced receptor expression, suggesting that HIV interferes with IL-23-activated signaling pathways. These findings may explain the inability of HAART to restore Th17 frequency and function and the resulting persistent chronic immune activation observed in HIV infected individuals.

INTRODUCTION:The complexity of immunity to malaria is well known, and clear correlates of protection against malaria have not been established. A better understanding of immune markers induced by candidate malaria vaccines would greatly enhance vaccine development, immunogenicity monitoring and estimation of vaccine efficacy in the field. We have previously reported complete or partial efficacy against experimental sporozoite challenge by several vaccine regimens in healthy malaria-naïve subjects in Oxford. These include a prime-boost regimen with RTS,S/AS02A and modified vaccinia virus Ankara (MVA) expressing the CSP antigen, and a DNA-prime, MVA-boost regimen expressing the ME TRAP antigens. Using samples from these trials we performed transcriptional profiling, allowing a global assessment of responses to vaccination. METHODS:We used Human RefSeq8 Bead Chips from Illumina to examine gene expression using PBMC (peripheral blood mononuclear cells) from 16 human volunteers. To focus on antigen-specific changes, comparisons were made between PBMC stimulated with CSP or TRAP peptide pools and unstimulated PBMC post vaccination. We then correlated gene expression with protection against malaria in a human Plasmodium falciparum malaria challenge model. RESULTS:Differentially expressed genes induced by both vaccine regimens were predominantly in the IFN-γ pathway. Gene set enrichment analysis revealed antigen-specific effects on genes associated with IFN induction and proteasome modules after vaccination. Genes associated with IFN induction and antigen presentation modules were positively enriched in subjects with complete protection from malaria challenge, while genes associated with haemopoietic stem cells, regulatory monocytes and the myeloid lineage modules were negatively enriched in protected subjects. CONCLUSIONS:These results represent novel insights into the immune repertoires involved in malaria vaccination.

Adenoviruses are potent vectors for inducing and boosting cellular immunity to encoded recombinant antigens. However, the widespread seroprevalence of neutralizing antibodies to common human adenovirus serotypes limits their use. Simian adenoviruses do not suffer from the same drawbacks. We have constructed a replication-deficient chimpanzee adenovirus-vectored vaccine expressing the conserved influenza antigens, nucleoprotein (NP), and matrix protein 1 (M1). Here, we report safety and T-cell immunogenicity following vaccination with this novel recombinant simian adenovirus, ChAdOx1 NP+M1, in a first in human dose-escalation study using a 3+3 study design, followed by boosting with modified vaccinia virus Ankara expressing the same antigens in some volunteers. We demonstrate ChAdOx1 NP+M1 to be safe and immunogenic. ChAdOx1 is a promising vaccine vector that could be used to deliver vaccine antigens where strong cellular immune responses are required for protection.