Intradermal delivery of the third dose of the mRNA-1273 SARS-CoV-2 vaccine: safety and immunogenicity of a fractional booster dose.

OBJECTIVES: The aim of this study was to assess the safety and immunogenicity of a dose-sparing fractional intradermal (ID) booster strategy with the mRNA-1273 COVID-19 vaccine. METHODS: COVID-19 naive adults aged 18-30 years were recruited from a previous study on primary vaccination regimens that compared 20 µg ID vaccinations with 100 µg intramuscular (IM) vaccinations with mRNA-1273 as the primary vaccination series. Participants previously immunized with ID regimens were randomly assigned (1:1) to receive a fractional ID booster dose (20 µg) or the standard-of-care intramuscular (IM) booster dose (50 µg) of the mRNA-1273 vaccine, 6 months after completing their primary series (ID-ID and ID-IM group, respectively). Participants that had received a full dose IM regimen as the primary series, received the IM standard-of-care booster dose (IM-IM group). In addition, COVID-19 naive individuals aged 18-40 years who had received an IM mRNA vaccine as the primary series were recruited from the general population to receive a fractional ID booster dose (IM-ID group). Immunogenicity was assessed using IgG anti-spike antibody responses and neutralizing capacity against SARS-CoV-2. Cellular immune responses were measured in a sub-group. Safety and tolerability were monitored. RESULTS: In January 2022, 129 participants were included in the study. Fractional ID boosting was safe and well tolerated, with fewer systemic adverse events compared with IM boosting. At day 28 post-booster, anti-spike S1 IgG geometric mean concentrations were 9106 (95% CI, 7150-11 597) binding antibody units (BAU)/mL in the IM-IM group and 4357 (3003-6322) BAU/mL; 6629 (4913-8946) BAU/mL; and 5264 (4032-6873) BAU/mL in the ID-IM, ID-ID, and IM-ID groups, respectively. DISCUSSION: Intradermal boosting provides robust immune responses and is a viable dose-sparing strategy for mRNA COVID-19 vaccines. The favourable side-effect profile supports its potential to reduce vaccine hesitancy. Fractional dosing strategies should be considered early in the clinical development of future mRNA vaccines to enhance vaccine availability and pandemic preparedness.

Immunogenicity and reactogenicity of intradermal mRNA-1273 SARS-CoV-2 vaccination: a non-inferiority, randomized-controlled trial.

Fractional dosing can be a cost-effective vaccination strategy to accelerate individual and herd immunity in a pandemic. We assessed the immunogenicity and safety of primary intradermal (ID) vaccination, with a 1/5th dose compared with the standard intramuscular (IM) dose of mRNA-1273 in SARS-CoV-2 naïve persons. We conducted an open-label, non-inferiority, randomized controlled trial in the Netherlands between June and December 2021. One hundred and fifty healthy and SARS-CoV-2 naïve participants, aged 18-30 years, were randomized (1:1:1) to receive either two doses of 20 µg mRNA-1273 ID with a standard needle (SN) or the Bella-mu® needle (BM), or two doses of 100 µg IM, 28 days apart. The primary outcome was non-inferiority in seroconversion rates at day 43 (D43), defined as a neutralizing antibody concentration threshold of 465 IU/mL, the lowest response in the IM group. The non-inferiority margin was set at -15%. Neutralizing antibody concentrations at D43 were 1789 (95% CI: 1488-2150) in the IM and 1263 (951-1676) and 1295 (1020-1645) in the ID-SN and ID-BM groups, respectively. The absolute difference in seroconversion proportion between fractional and standard-dose groups was -13.95% (-24.31 to -3.60) for the ID-SN and -13.04% (-22.78 to -3.31) for the ID-BM group and exceeded the predefined non-inferiority margin. Although ID vaccination with 1/5th dose of mRNA-1273 did not meet the predefined non-inferior criteria, the neutralizing antibody concentrations in these groups are far above the proposed proxy for protection against severe disease (100 IU/mL), justifying this strategy in times of vaccine scarcity to accelerate mass protection against severe disease.

Boostability after single-visit pre-exposure prophylaxis with rabies vaccine: a randomised controlled non-inferiority trial.

BACKGROUND: After rabies pre-exposure prophylaxis (PrEP) vaccination, scarcely available rabies immunoglobulins are not required for post-exposure prophylaxis (PEP). However, PrEP is not sufficiently accessible as it is cost-intensive and time-intensive. This study investigates whether rabies PrEP schedules can be shortened to one visit, removing some of these barriers. METHODS: In a block-randomised (2:2:2:1) controlled, multicentre non-inferiority trial, healthy adult travellers (aged 18-50 years and >50 years) were randomly assigned to (A) single-visit intramuscular (1·0 mL); (B) single-visit intradermal (0·2 mL); (C) standard two-visit intramuscular (1·0 mL; day 0 and 7) PrEP; or (D) no rabies vaccination. 6 months later, participants received simulated intramuscular rabies PEP (1·0 mL; day 0 and 3). Rabies virus neutralising antibody (RVNA) concentrations were measured repeatedly. The primary outcome was the fold increase in geometric mean RVNA concentrations between day 0 and 7 after simulated PEP for all participants. The two main comparisons of this primary outcome are between the standard two-visit schedule and the one-visit intramuscular schedule, and between the standard two-visit schedule and the one-visit intradermal schedule. The non-inferiority margin was 0·67. This study is registered with EudraCT, 2017-000089-31. FINDINGS: Between May 16, 2018, and March 26, 2020, 288 healthy adult travellers were randomly assigned and 214 participants were evaluated for the primary outcome. Single-visit intramuscular rabies PrEP induced an anamnestic antibody response non-inferior compared with the two-visit intramuscular schedule; single-visit intradermal PrEP did not. The fold increases in the single-visit intramuscular and the single-visit intradermal schedule were 2·32 (95% CI [1·43-3·77]) and 1·11 (0·66-1·87) times as high as the fold increase in the standard schedule, respectively. No vaccine-related serious adverse events were observed. Adverse events related to vaccination were mostly mild. INTERPRETATION: Single intramuscular rabies vaccination can effectively prime travellers (aged 18-50 years), and potentially other populations, and could replace current standard two-visit rabies vaccination as PrEP. FUNDING: ZonMW. TRANSLATION: For the Dutch translation of the abstract see Supplementary Materials section.

Establishing immunogenicity and safety of needle-free intradermal delivery by nanoporous ceramic skin patch of mRNA SARS-CoV-2 vaccine as a revaccination strategy in healthy volunteers.

INTRODUCTION: Nanoporous microneedle arrays (npMNA) are being developed as skin patches for vaccine delivery. As alternative for needle-based immunisation, they may potentially result in higher vaccine acceptance, which is important for future mass vaccination campaigns to control outbreaks, such as COVID-19, and for public vaccination in general. In this study we investigated the safety and immunogenicity of needle-free intradermal delivery of a fractional third or fourth dose of mRNA-1273 vaccine by npMNA. METHODS: This study was an open-label, randomised-controlled, proof-of-concept study. Healthy adults were eligible if they had received a primary immunisation series against SARS-CoV-2 with two doses of mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) mRNA vaccine. A history of a COVID-19 infection or booster vaccination with mRNA-1273 or BNT162b2 was allowed if it occurred at least three months before inclusion. Participants were randomised in a 1:1 ratio to receive 20 µg mRNA-1273 vaccine, either through npMNA patch applied on the skin (ID-patch group), or through intramuscular (IM) injection (IM-control group). Primary outcomes were reactogenicity up to two weeks after vaccination, and fold-increase of SARS-CoV-2 spike S1-specific IgG antibodies 14 days post-vaccination. RESULTS: In April 2022, 20 participants were enroled. The geometric mean concentration (GMC) did not increase in the ID-patch group after vaccination, in contrast to the IM-control group (GMC was 1,006 BAU/mL (95% CI 599-1,689), 3,855 (2,800-5,306), and 3,513 (2,554-4,833) at day 1, 15 and 29, respectively). In addition, SARS-CoV-2-specific T cell responses were lower after ID vaccination through npMNA. CONCLUSION: Needle-free delivery of 20 µg mRNA-1273 vaccine by npMNA failed to induce antibody and T cell responses. As this is a potentially very useful vaccination method, it is important to determine which adjustments are needed to make this npMNA successful. CLINICAL TRIAL REGISTRY (ON CLINICALTRIAL.GOV): NCT05315362.

Prolonged activation of nasal immune cell populations and development of tissue-resident SARS-CoV-2-specific CD8+ T cell responses following COVID-19.

Systemic immune cell dynamics during coronavirus disease 2019 (COVID-19) are extensively documented, but these are less well studied in the (upper) respiratory tract, where severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replicates1-6. Here, we characterized nasal and systemic immune cells in individuals with COVID-19 who were hospitalized or convalescent and compared the immune cells to those seen in healthy donors. We observed increased nasal granulocytes, monocytes, CD11c+ natural killer (NK) cells and CD4+ T effector cells during acute COVID-19. The mucosal proinflammatory populations positively associated with peripheral blood human leukocyte antigen (HLA)-DRlow monocytes, CD38+PD1+CD4+ T effector (Teff) cells and plasmablasts. However, there was no general lymphopenia in nasal mucosa, unlike in peripheral blood. Moreover, nasal neutrophils negatively associated with oxygen saturation levels in blood. Following convalescence, nasal immune cells mostly normalized, except for CD127+ granulocytes and CD38+CD8+ tissue-resident memory T cells (TRM). SARS-CoV-2-specific CD8+ T cells persisted at least 2 months after viral clearance in the nasal mucosa, indicating that COVID-19 has both transient and long-term effects on upper respiratory tract immune responses.

An Internet-Based Psychological Intervention With a Serious Game to Improve Vitality, Psychological and Physical Condition, and Immune Function in Healthy Male Adults: Randomized Controlled Trial.

BACKGROUND: Recently, internet-based cognitive behavioral therapy (ICBT) and serious gaming interventions have been suggested to enhance accessibility to interventions and engagement in psychological interventions that aim to promote health outcomes. Few studies, however, have investigated their effectiveness in the context of simulated real-life challenges. OBJECTIVE: We aimed to examine the effectivity of a guided ICBT combined with a serious gaming intervention in improving self-reported psychophysiological and immunological health endpoints in response to psychophysiological and immune-related challenges. METHODS: Sixty-nine healthy men were randomly assigned to the intervention condition, receiving ICBT combined with serious gaming for 6 weeks, or the control condition, receiving no intervention. Self-reported vitality was the primary endpoint. Other self-reported psychophysiological and immunological endpoints were assessed following various challenges, including a bacillus Calmette-Guérin vaccination evoking pro-inflammatory responses, 1 and 4 weeks after the intervention period. RESULTS: Although the intervention did not affect vitality-associated parameters, self-reported sleep problems (P=.027) and bodily sensations (P=.042) were lower directly after the intervention compared with controls. Furthermore, wellbeing (P=.024) was higher in the intervention group after the psychophysiological challenges. Although no significant group differences were found for the psychophysiological and immunological endpoints, the data provided preliminary support for increased immunoglobulin antibody responses at the follow-up time points (P<.05). Differential chemokine endpoints between conditions were observed at the end of the test day. CONCLUSIONS: The present study provides some support for improving health endpoints with an innovative ICBT intervention. Future research should replicate and further extend the present findings by consistently including challenges and a wide range of immune parameters into the study design. TRIAL REGISTRATION: Nederlands Trial Register NTR5610; https://www.trialregister.nl/trial/5466.

Abnormalities suggestive of latent tuberculosis infection on chest radiography; how specific are they?

BACKGROUND: Several radiological features have been reported in association with latent tuberculosis infection (LTBI) but it has not been studied which are specific. The aim of this study was to evaluate allegedly characteristic abnormalities on chest radiography (CXR) in patients with LTBI compared to uninfected controls. METHODS: From 236 patients tested with QuantiFERON-TB Gold In-Tube (QFT), the CXR was re-evaluated in a blinded fashion for fibrotic scarring, (non-)calcified nodules and pleural thickening. LTBI was defined as presence of a positive QFT result and/or positive tuberculin skin test result stratified by Bacille Calmette-Guérin-vaccination status. RESULTS: Any predefined abnormality of LTBI was observed in 116/236 (49.2%) patients, the frequency not being different between groups. However, the specificity for LTBI of a fibrotic scar ≥ 2 cm2 was 100% [95% CI: 92.0%-100%] and of a calcified nodule ≥1.5 mm was 95.7% [95% CI: 85.2%-99.5%]. The frequency of non-calcified nodules and pleural thickening did not differ between groups. CONCLUSION: Only a fibrotic scar ≥ 2 cm2 and/or a calcified nodule ≥1.5 mm were significantly associated with LTBI. This finding is clinically relevant mainly in patients who are at significant risk of TB reactivation and in whom indirect diagnostic tests may be unreliable.

A novel view on the pathogenesis of complications after intravesical BCG for bladder cancer.

Intravesical bacillus Calmette-Guérin (BCG) is widely used for high-risk, non-muscle-invasive bladder cancer. This report describes four cases that illustrate the spectrum of BCG-induced complications, varying from granulomatous prostatitis to sepsis. There is considerable debate regarding whether inflammation or infection is the predominant mechanism in the pathogenesis of BCG disease. In two patients with a systemic illness, the symptoms first resolved after adding prednisone, indicating a principal role for inflammation in systemic disease. In vitro testing of T-cell responses and a mycobacterial growth inhibition assay were performed for these patients with systemic disease. The patient with mild symptoms showed more effective in vitro growth reduction of BCG, while the patient with sepsis and organ involvement had high T-cell responses but ineffective killing. While these findings are preliminary, it is believed that immunological assays, as described in this report, may provide a better insight into the pathogenesis of BCG disease in individual patients, justifying further research.

Mycobacterial growth inhibition is associated with trained innate immunity.

The lack of defined correlates of protection hampers development of vaccines against tuberculosis (TB). In vitro mycobacterial outgrowth assays are thought to better capture the complexity of the human host/Mycobacterium tuberculosis (Mtb) interaction. Here, we used a mycobacterial growth inhibition assay (MGIA) based on peripheral blood mononuclear cells to investigate the capacity to control outgrowth of bacille Calmette-Guérin (BCG). Interestingly, strong control of BCG outgrowth was observed almost exclusively in individuals with recent exposure to Mtb, but not in (long-term) latent TB infection, and only modestly in BCG vaccinees. Mechanistically, control of mycobacterial outgrowth strongly correlated with the presence of a CD14dim monocyte population, but also required the presence of T cells. The nonclassical monocytes produced CXCL10, and CXCR3 receptor blockade inhibited the capacity to control BCG outgrowth. Expression of CXCR3 splice variants was altered in recently Mtb-exposed individuals. Cytokines previously associated with trained immunity were detected in MGIA supernatants, and CXCL9, CXCL10, and CXCL11 represent new markers of trained immunity. These data indicate that CXCR3 ligands are associated with trained immunity and are critical factors in controlling mycobacterial outgrowth. In conclusion, control of mycobacterial outgrowth early after exposure to Mtb is the result of trained immunity mediated by a CXCL10-producing nonclassical CD14dim monocyte subset.

Immunological characterization of latent tuberculosis infection in a low endemic country.

The diagnosis of a latent tuberculosis infection (LTBI) is based on detection of immunity against Mycobacterium tuberculosis (Mtb). The tuberculin skin test (TST), the Quantiferon (QFT) and a prolonged lymphocyte stimulation test using either ESAT-6/CFP-10 (LST-EC) or PPD (LST-PPD) were evaluated in a cohort of 495 individuals, suspected to have LTBI, in a low endemic country. While the TST and LST-PPD were both positive in the majority (75%) of individuals, only one third responded in the LST-EC and in the QFT. The choice for LTBI treatment was significantly associated with ESAT6/CFP10 recognition, however the LST-EC detected considerably more individuals (21%) with immunity against Mtb, who might also be at risk for development of active TB, although none of them did during follow up. Follow-up for 2 years showed 7% conversions and 32% reversions for the QFT. The LST-EC showed higher conversion rates (∼45%), although the percentage of individuals positive in the LST-EC did not change significantly within the follow-up period. LTBI treatment did not alter immune recognition of Mtb antigens. In conclusion, the sensitivity of tests for detection of cellular immunity to Mtb specific antigens depends on test methodology and may vary considerably over time in a low endemic region.

The effects of a psychological intervention directed at optimizing immune function: study protocol for a randomized controlled trial.

BACKGROUND: Previous research has provided evidence for the link between psychological processes and psychophysiological health outcomes. Psychological interventions, such as face-to-face or online cognitive behavioral therapy (CBT) and serious games aimed at improving health, have shown promising results in promoting health outcomes. Few studies so far, however, have examined whether Internet-based CBT combined with serious gaming elements is effective in modulating health outcomes. Moreover, studies often did not incorporate psychophysiological or immunological challenges in order to gain insight into physiological responses to real-life challenges after psychological interventions. The overall aim of this study is to investigate the effects of a psychological intervention on self-reported and physiological health outcomes in response to immune and psychophysiological challenges. METHODS/DESIGN: In a randomized controlled trial, 60 healthy men are randomly assigned to either an experimental condition, receiving guided Internet-based (e-health) CBT combined with health-related serious gaming elements for 6 weeks, or a control condition receiving no intervention. After the psychological intervention, self-reported vitality is measured, and participants are given an immunological challenge in the form of a Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccination. One day after the vaccination, participants are asked to perform several psychophysiological tasks in order to explore the effects of the psychological intervention on participants' stress response following the immune challenge. To assess the delayed effects of vaccination on self-reported and physiological health outcomes, a follow-up visit is planned 4 weeks later. Total study duration is approximately 14 weeks. The primary outcome measure is self-reported vitality measured directly after the intervention. Secondary outcome measures include inflammatory and endocrine markers, as well as psychophysiological measures of heart rate and skin conductance in response to the psychophysiological tasks after the BCG vaccination. DISCUSSION: The innovative design features of this study - e.g., combining guided e-health CBT with health-related serious gaming elements and incorporating immunological and psychophysiological challenges - will provide valuable information on the effects of a psychological intervention on both self-reported and physiological health outcomes. This study will offer further insights into the mechanisms underlying the link between psychological factors and health outcomes and is anticipated to contribute to the optimization of health care strategies. TRIAL REGISTRATION: Nederlands Trial Register, NTR5610 . Registered on 4 January 2016.

New Genome-Wide Algorithm Identifies Novel In-Vivo Expressed Mycobacterium Tuberculosis Antigens Inducing Human T-Cell Responses with Classical and Unconventional Cytokine Profiles.

New strategies are needed to develop better tools to control TB, including identification of novel antigens for vaccination. Such Mtb antigens must be expressed during Mtb infection in the major target organ, the lung, and must be capable of eliciting human immune responses. Using genome-wide transcriptomics of Mtb infected lungs we developed data sets and methods to identify IVE-TB (in-vivo expressed Mtb) antigens expressed in the lung. Quantitative expression analysis of 2,068 Mtb genes from the predicted first operons identified the most upregulated IVE-TB genes during in-vivo pulmonary infection. By further analysing high-level conservation among whole-genome sequenced Mtb-complex strains (n = 219) and algorithms predicting HLA-class-Ia and II presented epitopes, we selected the most promising IVE-TB candidate antigens. Several of these were recognized by T-cells from in-vitro Mtb-PPD and ESAT6/CFP10-positive donors by proliferation and multi-cytokine production. This was validated in an independent cohort of latently Mtb-infected individuals. Significant T-cell responses were observed in the absence of IFN-γ-production. Collectively, the results underscore the power of our novel antigen discovery approach in identifying Mtb antigens, including those that induce unconventional T-cell responses, which may provide important novel tools for TB vaccination and biomarker profiling. Our generic approach is applicable to other infectious diseases.

KLRG1 and PD-1 expression are increased on T-cells following tuberculosis-treatment and identify cells with different proliferative capacities in BCG-vaccinated adults.

In cancer and chronic infectious diseases, immune checkpoint-blockade of inhibitory receptors can enhance T-cell immunity. In tuberculosis (TB), a chronic infectious disease, prolonged antigen exposure can potentially drive terminal T-cell differentiation towards functional 'exhaustion': in human TB T-cells express PD-1 (programmed cell death protein-1) and CTLA-4 (cytotoxic T-lymphocyte-associated protein-4). However, in murine TB not PD-1 but rather killer cell lectin-like receptor subfamily-G1 (KLRG1) was a superior indicator of terminal T-cell differentiation. We therefore compared expression of KLRG1, PD-1 and CTLA-4 on T-cells in different stages of human TB, and also analysed their induction following BCG-vaccination. KLRG1, PD-1 and CTLA-4-expression were highest on in vitro BCG-stimulated CD4(+) T-cells following recent TB-treatment; KLRG1 and PD-1-expression on CD4(+) T-cells in active--but not latent--TB were only slightly increased compared to healthy donors. BCG-vaccination induced KLRG1-expression on BCG-stimulated CD8(+) but not CD4(+) T-cells, while neither PD-1 nor CTLA-4-expression increased. KLRG1-expressing CD8(+) T-cells exhibited markedly decreased proliferation, whereas PD-1(+) T-cells proliferated after in vitro BCG-stimulation. Thus, we demonstrate the presence of increased KLRG1-expressing T-cells in TB-treated individuals, and present KLRG1 as a marker of decreased human T-cell proliferation following BCG-vaccination. These results expand our understanding of cell-mediated immune control of mycobacterial infections.

Mycobacterium bovis BCG Vaccination Induces Divergent Proinflammatory or Regulatory T Cell Responses in Adults.

Mycobacterium bovis bacillus Calmette-Guérin (BCG), the only currently available vaccine against tuberculosis, induces variable protection in adults. Immune correlates of protection are lacking, and analyses on cytokine-producing T cell subsets in protected versus unprotected cohorts have yielded inconsistent results. We studied the primary T cell response, both proinflammatory and regulatory T cell responses, induced by BCG vaccination in adults. Twelve healthy adult volunteers who were tuberculin skin test (TST) negative, QuantiFERON test (QFT) negative, and BCG naive were vaccinated with BCG and followed up prospectively. BCG vaccination induced an unexpectedly dichotomous immune response in this small, BCG-naive, young-adult cohort: BCG vaccination induced either gamma interferon-positive (IFN-γ(+)) interleukin 2-positive (IL-2(+)) tumor necrosis factor α-positive (TNF-α(+)) polyfunctional CD4(+) T cells concurrent with CD4(+) IL-17A(+) and CD8(+) IFN-γ(+) T cells or, in contrast, virtually absent cytokine responses with induction of CD8(+) regulatory T cells. Significant induction of polyfunctional CD4(+) IFN-γ(+) IL-2(+) TNF-α(+) T cells and IFN-γ production by peripheral blood mononuclear cells (PBMCs) was confined to individuals with strong immunization-induced local skin inflammation and increased serum C-reactive protein (CRP). Conversely, in individuals with mild inflammation, regulatory-like CD8(+) T cells were uniquely induced. Thus, BCG vaccination either induced a broad proinflammatory T cell response with local inflammatory reactogenicity or, in contrast, a predominant CD8(+) regulatory T cell response with mild local inflammation, poor cytokine induction, and absent polyfunctional CD4(+) T cells. Further detailed fine mapping of the heterogeneous host response to BCG vaccination using classical and nonclassical immune markers will enhance our understanding of the mechanisms and determinants that underlie the induction of apparently opposite immune responses and how these impact the ability of BCG to induce protective immunity to TB.

A novel liposomal adjuvant system, CAF01, promotes long-lived Mycobacterium tuberculosis-specific T-cell responses in human.

Here, we report on a first-in-man trial where the tuberculosis (TB) vaccine Ag85B-ESAT-6 (H1) was adjuvanted with escalating doses of a novel liposome adjuvant CAF01. On their own, protein antigens cannot sufficiently induce immune responses in humans, and require the addition of an adjuvant system to ensure appropriate delivery and concomitant immune activation. To date no approved adjuvants are available for induction of cellular immunity, which seems essential for a number of vaccines, including vaccines against TB. We vaccinated four groups of human volunteers: a non-adjuvanted H1 group, followed by three groups with escalating doses of CAF01-adjuvanted H1 vaccine. All subjects were vaccinated at 0 and 8 weeks and followed up for 150 weeks. Vaccination did not cause local or systemic adverse effects besides transient soreness at the injection site. Two vaccinations elicited strong antigen-specific T-cell responses which persisted after 150 weeks follow-up, indicating the induction of a long-lasting memory response in the vaccine recipients. These results show that CAF01 is a safe and tolerable, Th1-inducing adjuvant for human TB vaccination trials and for vaccination studies in general where cellular immunity is required.

An unbiased genome-wide Mycobacterium tuberculosis gene expression approach to discover antigens targeted by human T cells expressed during pulmonary infection.

Mycobacterium tuberculosis is responsible for almost 2 million deaths annually. Mycobacterium bovis bacillus Calmette-Guérin, the only vaccine available against tuberculosis (TB), induces highly variable protection against TB, and better TB vaccines are urgently needed. A prerequisite for candidate vaccine Ags is that they are immunogenic and expressed by M. tuberculosis during infection of the primary target organ, that is, the lungs of susceptible individuals. In search of new TB vaccine candidate Ags, we have used a genome-wide, unbiased Ag discovery approach to investigate the in vivo expression of 2170 M. tuberculosis genes during M. tuberculosis infection in the lungs of mice. Four genetically related but distinct mouse strains were studied, representing a spectrum of TB susceptibility controlled by the supersusceptibility to TB 1 locus. We used stringent selection approaches to select in vivo-expressed M. tuberculosis (IVE-TB) genes and analyzed their expression patterns in distinct disease phenotypes such as necrosis and granuloma formation. To study the vaccine potential of these proteins, we analyzed their immunogenicity. Several M. tuberculosis proteins were recognized by immune cells from tuberculin skin test-positive, ESAT6/CFP10-responsive individuals, indicating that these Ags are presented during natural M. tuberculosis infection. Furthermore, TB patients also showed responses toward IVE-TB Ags, albeit lower than tuberculin skin test-positive, ESAT6/CFP10-responsive individuals. Finally, IVE-TB Ags induced strong IFN-γ(+)/TNF-α(+) CD8(+) and TNF-α(+)/IL-2(+) CD154(+)/CD4(+) T cell responses in PBMC from long-term latently M. tuberculosis-infected individuals. In conclusion, these IVE-TB Ags are expressed during pulmonary infection in vivo, are immunogenic, induce strong T cell responses in long-term latently M. tuberculosis-infected individuals, and may therefore represent attractive Ags for new TB vaccines.

Ag85B-ESAT-6 adjuvanted with IC31® promotes strong and long-lived Mycobacterium tuberculosis specific T cell responses in volunteers with previous BCG vaccination or tuberculosis infection.

New TB vaccines are urgently needed because of the apparent lack of effect of the BCG vaccine on rates of adult contagious pulmonary tuberculosis and the risk of disseminated BCG disease in immunocompromised individuals. Since BCG appears to protect children, the primary target for vaccine development is a booster vaccine for adults but such vaccines ideally need to be able to efficiently prime mycobacterially naïve individuals as well as boost individuals previously vaccinated with BCG and those latently infected with TB. Protective immunity against Mycobacterium tuberculosis depends mainly on the generation of a Th1-type cellular immune response characterized by interferon-gamma (IFN-γ) production. In the present study, we monitored safety and IFN-γ responses in healthy BCG-vaccinated and prior or latently TB-infected individuals receiving a novel vaccine composed of the fusion protein Ag85B-ESAT-6 combined with the adjuvant IC31(®), administered at 0 and 2 months. Vaccination caused few local or systemic adverse effects besides transient soreness at the injection site, but it elicited strong antigen-specific T cell responses against Ag85B-ESAT-6 and both the Ag85B and ESAT-6 components, that could be augmented by second vaccination. The strong responses persisted through 32 weeks of follow-up, indicating the induction of a persistent memory response in the vaccine recipients.

Ag85B-ESAT-6 adjuvanted with IC31 promotes strong and long-lived Mycobacterium tuberculosis specific T cell responses in naïve human volunteers.

Though widely used, the BCG vaccine has had little apparent effect on rates of adult pulmonary tuberculosis. Moreover, the risk of disseminated BCG disease in immunocompromised individuals means that improved TB vaccines ideally need to be able to efficiently prime mycobacterially-naïve individuals as well as boost individuals previously vaccinated with BCG. Protective immunity against Mycobacterium tuberculosis is thought to depend on the generation of a Th1-type cellular immune response characterized by interferon-gamma (IFN-gamma) production. In the present study, we monitored safety and IFN-gamma responses in healthy TB-naïve humans receiving an entirely novel vaccine, composed of the fusion protein Ag85B-ESAT-6, administered at 0 and 2 months either as recombinant protein alone or combined with two concentrations of the novel adjuvant IC31. Vaccination did not cause local or systemic adverse effects besides transient soreness at the injection site, but it elicited strong antigen-specific T cell responses against H1 and both the Ag85B and the ESAT-6 components. These strong responses persisted through 2.5 years of follow-up, indicating the induction of a substantial memory response in the vaccine recipients.