Tuberculosis is the deadliest infection of our time. In contrast, about 11,000 people died of Ebola between 2014 and 2016. Despite this manifest difference in mortality, there is now a vaccine licensed in the United States and by the European Medicines Agency, with up to 100% efficacy against Ebola. The developments that led to the trialing of the Ebola vaccine were historic and unprecedented. The single licensed TB vaccine (BCG) has limited efficacy. There is a dire need for a more efficacious TB vaccine. To deploy such vaccines, trials are needed in sites that combine high disease incidence and research infrastructure. We describe our twelve-year experience building a TB vaccine trial site in contrast to the process in the recent Ebola outbreak. There are additional differences. Relative to the Ebola pipeline, TB vaccines have fewer trials and a paucity of government and industry led trials. While pathogens have varying levels of difficulty in the development of new vaccine candidates, there yet appears to be greater interest in funding and coordinating Ebola interventions. TB is a global threat that requires similar concerted effort for elimination.

Paediatric laboratory reference intervals used in Africa and Asia may be derived from historical intervals of predominantly Caucasian infants in Europe or North America. These intervals may therefore not be compatible with the range of normality for developing country populations. We aimed to compare haematology and biochemistry parameters in healthy South African infants with local laboratory reference intervals.

Background— Identification of blood biomarkers that prospectively predict progression of Mycobacterium tuberculosis infection to tuberculosis disease may lead to interventions that impact the epidemic. Methods— Healthy, M. tuberculosis infected South African adolescents were followed for 2 years; blood was collected every 6 months. A prospective signature of risk was derived from whole blood RNA-Sequencing data by comparing participants who ultimately developed active tuberculosis disease (progressors) with those who remained healthy (matched controls). After adaptation to multiplex qRT-PCR, the signature was used to predict tuberculosis disease in untouched adolescent samples and in samples from independent cohorts of South African and Gambian adult progressors and controls. The latter participants were household contacts of adults with active pulmonary tuberculosis disease.

Background Identification of blood biomarkers that prospectively predict progression of Mycobacterium tuberculosis infection to tuberculosis disease might lead to interventions that combat the tuberculosis epidemic. We aimed to assess whether global gene expression measured in whole blood of healthy people allowed identification of prospective signatures of risk of active tuberculosis disease.Methods In this prospective cohort study, we followed up healthy, South African adolescents aged 12-18 years from the adolescent cohort study (ACS) who were infected with M tuberculosis for 2 years. We collected blood samples from study participants every 6 months and monitored the adolescents for progression to tuberculosis disease. A prospective signature of risk was derived from whole blood RNA sequencing data by comparing participants who developed active tuberculosis disease (progressors) with those who remained healthy (matched controls). After adaptation to multiplex quantitative real-time PCR (qRT-PCR), the signature was used to predict tuberculosis disease in untouched adolescent samples and in samples from independent cohorts of South African and Gambian adult progressors and controls. Participants of the independent cohorts were household contacts of adults with active pulmonary tuberculosis disease.Findings Between July 6, 2005, and April 23, 2007, we enrolled 6363 participants from the ACS study and 4466 from independent South African and Gambian cohorts. 46 progressors and 107 matched controls were identified in the ACS cohort. A 16 gene signature of risk was identified. The signature predicted tuberculosis progression with a sensitivity of 66.1% (95% CI 63.2-68.9) and a specificity of 80.6% (79.2-82.0) in the 12 months preceding tuberculosis diagnosis. The risk signature was validated in an untouched group of adolescents (p= 0.018 for RNA sequencing and p= 0.0095 for qRT-PCR) and in the independent South African and Gambian cohorts (p values < 0.0001 by qRT-PCR) with a sensitivity of 53.7% (42.6-64.3) and a specificity of 82.8% (76.7-86) in the 12 months preceding tuberculosis.Interpretation The whole blood tuberculosis risk signature prospectively identified people at risk of developing active tuberculosis, opening the possibility for targeted intervention to prevent the disease.

BACKGROUND:There is an urgent need for improved vaccines to protect against tuberculosis. The currently available vaccine Bacille Calmette-Guerin (BCG) has varying immunogenicity and efficacy across different populations for reasons not clearly understood. MVA85A is a modified vaccinia virus expressing antigen 85A from Mycobacterium tuberculosis which has been in clinical development since 2002 as a candidate vaccine to boost BCG-induced protection. A recent efficacy trial in South African infants failed to demonstrate enhancement of protection over BCG alone. The immunogenicity was lower than that seen in UK trials. The enzyme Indoleamine 2,3-dioxygenase (IDO) catalyses the first and rate-limiting step in the breakdown of the essential amino acid tryptophan. T cells are dependent on tryptophan and IDO activity suppresses T-cell proliferation and function.METHODS:Using samples collected during phase I trials with MVA85A across the UK and South Africa we have investigated the relationship between vaccine immunogenicity and IDO using IFN-γ ELISPOT, qPCR and liquid chromatography mass spectrometry.RESULTS:We demonstrate an IFN-γ dependent increase in IDO mRNA expression in peripheral blood mononuclear cells (PBMC) following MVA85A vaccination in UK subjects. IDO mRNA correlates positively with the IFN-γ ELISPOT response indicating that vaccine specific induction of IDO in PBMC is unlikely to limit the development of vaccine specific immunity. IDO activity in the serum of volunteers from the UK and South Africa was also assessed. There was no change in serum IDO activity following MVA85A vaccination. However, we observed higher baseline IDO activity in South African volunteers when compared to UK volunteers. In both UK and South African serum samples, baseline IDO activity negatively correlated with vaccine-specific IFN-γ responses, suggesting that IDO activity may impair the generation of a CD4+ T cell memory response.CONCLUSIONS:Baseline IDO activity was higher in South African volunteers when compared to UK volunteers, which may represent a potential mechanism for the observed variation in vaccine immunogenicity in South African and UK populations and may have important implications for future vaccination strategies.TRIAL REGISTRATION:Trials are registered at ClinicalTrials.gov; UK cohort NCT00427830, UK LTBI cohort NCT00456183, South African cohort NCT00460590, South African LTBI cohort NCT00480558.

Screening for tuberculosis (TB) disease is important for TB control and TB vaccine efficacy trials but this has not been evaluated in adolescents. We conducted a study to determine the prevalence of active TB and performance of specific screening tests for TB in adolescents in a high burden setting. Adolescents aged 12–18 years were recruited from high schools in a rural town in South Africa. Participants were screened for active TB using symptoms, household TB contact, positive interferon gamma release assay (IGRA) and positive tuberculin skin test (TST). Of 6363 adolescents recruited, 21 were newly diagnosed with TB of whom 19 were culture positive. After exclusions, the derived prevalence of smear positive TB was 16/5682 = 3/1000 (95% confidence interval (CI) 1–4/1000). The sensitivity of TST and IGRA for active TB were 85% (95% CI 62–100%) and 94% (95% CI 79–100%) respectively. None of the methods alone or in combination had positive predictive values greater than 2%. The screening tools evaluated in this study may not be practical for routine use owing to low positive predictive values but may be useful in TB vaccine clinical trials.

Background: Tuberculosis (TB) is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa.Methods: We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST) performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment.Results: A total of 6,363 adolescents were enrolled (58% of the school population targeted). During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.29-0.72). Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis.Conclusion: The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease.

Tuberculosis in infants and young children remains an all too common cause of morbidity and mortality in high burden countries, despite the fact that the majority of these children receive vaccination with BCG in infancy. BCG confers incomplete and variable protection against pulmonary tuberculosis [PTB] and is unsafe in HIV positive persons. Newer TB vaccines, which, it is hoped, will either replace or complement BCG are being developed and a number of these have reached the stage of clinical trials, with two booster vaccines going into Phase IIB trials in 2009. Prospects for at least one new licensed TB vaccine within the next 5-10 years appear reasonable. This article explores some of the issues around the development of new vaccines against TB and details the leading candidates.

The endpoint definition for infant tuberculosis (TB) vaccine trials should match the TB disease phenotype expected in the control arm of the study population. Our aim was to analyse selected combinations of the clinical, radiological, and microbiological features of pulmonary TB among children investigated under vaccine trial conditions, in order to estimate case frequency for a range of expected TB phenotypes. Two thousand one hundred and eighty five South African children were investigated over a nine-year period (2001-2009). Evidence of TB exposure and classical symptoms were several times more common than chest radiography (CXR) compatible with TB, or positive Mycobacterium tuberculosis culture. Discordance between clinical, radiological, and microbiological features was common in individual children. Up to one third of children with compatible CXR, and up to half the children who were M. tuberculosis culture positive, were asymptomatic. The culture positive rate fell over time, although rates of TB exposure and compatible chest radiography increased. Consequently, the annual incidence of diagnostic combinations that included M. tuberculosis culture fell to <0.2%. However, in this study population (children <2 years of age), annual incidence of the TB disease phenotype that included the triad of TB exposure, symptoms, and compatible CXR, approached 1% (n=848 per 100,000). These findings allow modelling of expected TB case frequency in multi-centre infant TB vaccine trials, based upon benchmarking of diagnostic data against the key indicator variables that constitute the building blocks of a trial endpoint.

SETTING:A high tuberculosis (TB) burden area in South Africa (notification rate for all TB cases 1400 per 100 000 population). OBJECTIVE:To determine the prevalence of and predictive factors associated with latent TB infection in adolescents. DESIGN:Adolescents aged 12-18 years were recruited from high schools, clinical and demographic data were collected, and a tuberculin skin test (TST) and a QuantiFERON®-TB Gold In-Tube (QFT) assay performed. RESULTS:A total of 6363 (58.2%) of 10 942 adolescents at the schools were enrolled. After exclusions, of 5244 participants, 55.2% (95%CI 53.8-56.5) had TST ≥ 5 mm, while 50.9% (49.5-52.2) were QFT-positive. On multivariate analysis, Black/mixed race racial groups, male sex, older age, household TB contact, low income and low education level were predictive factors for both TST- and QFT-positive results. CONCLUSION:About half of the adolescents were found to be latently infected with TB in a high TB burden area with demographic and poverty-related socio-economic factors predicting the risk of TB infection. Adolescents from deprived communities should be considered an important target group for educational interventions by TB control programmes in high-burden settings.

Setting: This study was conducted in a high tuberculosis (TB) burden area in Worcester, South Africa, with a notified all TB incidence rate of 1,400/100,000.Main Objective: To compare the predictive value of a baseline tuberculin skin test (TST) with that of the QuantiFERON TB Gold (In-tube) assay (QFT) for subsequent microbiologically confirmed TB disease among adolescents.Methods: Adolescents aged 12-18 years were recruited from high schools in the study area. At baseline, blood was drawn for QFT and a TST administered. Participants were followed up for up to 3.8 years for incident TB disease (median 2.4 years).Results: After exclusions, 5244 (82.4%) of 6,363 adolescents enrolled, were analysed. The TB incidence rate was 0.60 cases per 100 person years (pyrs) (95% CI 0.43-0.82) for baseline TST positive (>= 5 mm) participants and 0.64 cases per 100 pyrs (95% CI 0.45-0.87) for baseline QFT positive participants. TB incidence rates were 0.22 per 100 pyrs (0.11-0.39) and 0.22 per 100 pyrs (0.12-0.38) among those with a negative baseline TST and QFT respectively. Sensitivity for incident TB disease was 76.9% for TST and 75.0% for QFT (p = 0.81). Positive predictive value was 1.4% for TST and 1.5% for QFT.Conclusion: Positive TST and QFT tests were moderately sensitive predictors of progression to microbiologically confirmed TB disease. There was no significant difference in the predictive ability of these tests for TB disease amongst adolescents in this high burden setting. Therefore, these findings do not support use of QFT in preference to TST to predict the risk of TB disease in this study population.

Many HIV-infected infants progress to AIDS during the first year of life when antiretroviral therapy (ART) is not given. The immune determinants of progression to AIDS are not known. We hypothesized that distinct HIV-specific T cell responses correlate with viral load and survival over the first year of life. Whole blood of infants at 3, 6, 9, and 12 months of age was incubated with HIV antigens Gag and Env. The frequency of specific T cells producing interferon (IFN)-γ was then measured by flow cytometry. Viral load and CD4% in HIV+ infants were determined at each time point. ART was not available for this population at the time of sample collection. Those infants who survived to 12 months of age (n=12) had lower viral loads and higher Gag-specific CD8+ T cell responses at 3 months, compared with infants who died (n=8). Furthermore, the frequency of Gag-specific CD4+ T cells correlated inversely with viral load at 3 and 6 months of age. Together these data indicate that the early presence of quantitatively higher Gag-specific T cell responses in HIV-infected infants is associated with lower viral loads and decreased mortality in the first year of life. Our data support the design of a vaccine that preferentially elicits Gag responses, which may result in lower levels of viremia and possibly improve outcome.

Introduction Despite scale of worldwide tuberculosis epidemic, disease remains very difficult to diagnose in children, especially in regions with limited resources. (1) Childhood tuberculosis is often paucibacillary and diagnosis rests on interpretation of chest radiograph findings and non-specific symptoms and signs. I Improving diagnostic accuracy and reliability is key to integrating childhood tuberculosis into national control programmes, and World Health Organization (WHO) has thus prioritized diagnostic criteria for childhood tuberculosis. (2) Objective, reproducible tuberculosis diagnosis will also be pivotal for defining end-points in trials of new tuberculosis vaccines. (3) The need for accurate diagnosis is felt most acutely among younger children, who contribute substantially to burden of tuberculosis in high prevalence regions. (4-7) Routine clinical use of a structured diagnostic approach that is unsuited to a particular setting can result in systematic errors in estimating burden of tuberculosis and in patient management. It follows that regional guidelines for screening and diagnosis of childhood tuberculosis should be tailored to their epidemiological context. The relative merits of existing structured diagnostic approaches are debatable. (5,8-17) Hesseling et al. reviewed 16 such approaches and noted that few of scoring systems, algorithms and classifications for screening and diagnosis of childhood tuberculosis have been validated against a gold standard. Most have been developed for hospital-based studies and their useful-ness in community settings is relatively unknown. (5,18-21) Some have suggested that structured diagnostic approaches should be used only as screening tools to select children for further investigation, (9,10) while others have proposed a simplified case definition of childhood tuberculosis, based on cardinal symptoms, as an alternative to complex diagnostic systems. (1,22) Existing structured approaches to childhood tuberculosis provide a logical and reproducible basis for diagnosis based on clinical acumen, which Cundall termed the art of possible. (23) However, we hypothesized that commonly used, structured approaches for screening and diagnosing childhood tuberculosis may show poor agreement and yield highly variable case frequency results. The objectives of this paper were to quantify tuberculosis case frequencies obtained by means of nine different diagnostic systems, to assess agreement between systems, and to offer possible explanations for discordant findings. Methods This analysis is based on data collected during a bacille Calmette-Guerin (BCG) vaccine trial conducted by South African Tuberculosis Vaccine Initiative (SATVI) from March 2001 to August 2006 near Cape Town, South Africa (clinical trials identifier: NCT00242047). (8) In Boland-Overberg region of South Africa, tuberculosis incidence among children aged 3000 cases per 100 000 in 2006. (6,8,24) In trial, which compared vaccine efficacy obtained with percutaneous versus intradermal Tokyo-172 BCG, 11 680 neonates were followed up for a minimum of 2 years after vaccination. (8) Children in community suspected of having tuberculosis due to a history of contact with an adult case or to presence of symptoms compatible with disease were identified by a regional surveillance system. Ali such children underwent comprehensive radiological and bacteriological investigation, even if they had no symptoms. The presence and duration of cough, wheezing, fever or weight loss; response to antibiotics; and proximity of contact with an adult having tuberculosis (mother, other person within household, person outside of household), were recorded. Human immunodeficiency virus (HIV) status was determined by a rapid antibody test and, if result was positive, confirmatory polymerase chain reaction (PCR) was performed as well. …

OBJECTIVE To measure agreement between nine structured approaches for diagnosing childhood tuberculosis; to quantify differences in the number of tuberculosis cases diagnosed with the different approaches, and to determine the distribution of cases in different categories of diagnostic certainty. METHODS We investigated 1445 children aged < 2 years during a vaccine trial (2001-2006) in a rural South African community. Clinical, radiological and microbiological data were collected prospectively. Tuberculosis case status was determined using each of the nine diagnostic approaches. We calculated differences in case frequency and categorical agreement for binary (tuberculosis/not tuberculosis) outcomes using McNemar's test (with 95% confidence intervals, CIs) and Cohen's kappa coefficient (Kappa). FINDINGS Tuberculosis case frequency ranged from 6.9% to 89.2% (median: 41.7). Significant differences in case frequency (P < 0.05) occurred in 34 of the 36 pair-wise comparisons between structured diagnostic approaches (range of absolute differences: 1.5-82.3%). Kappa ranged from 0.02 to 0.71 (median: 0.18). The two systems that yielded the highest case frequencies (89.2% and 70.0%) showed fair agreement (Kappa: 0.33); the two that yielded the lowest case frequencies (6.9% and 10.0%) showed slight agreement (Kappa: 0.18). CONCLUSION There is only slight agreement between structured approaches for the screening and diagnosis of childhood tuberculosis and high variability between them in terms of case yield. Diagnostic systems that yield similarly low case frequencies may be identifying different subpopulations of children. The study findings do not support the routine clinical use of structured approaches for the definitive diagnosis of childhood tuberculosis, although high-yielding systems may be useful screening tools.

Tuberculosis (TB) is one of the world’s leading causes of death due to infection and efforts to control TB would be substantially aided by the availability of an improved TB vaccine. There are currently nine new TB vaccines in clinical development, and the first efficacy trials are due to commence in 2009. There are many complex ethical issues which arise at all stages of TB vaccine development, from the need to conduct trials in developing countries to informed consent and the process of ethical review. While it is important that these issues are discussed, it may also be timely to consider the challenges which may arise if a vaccine in clinical development proves to be highly effective. We examine a number of scenarios where decisions on the deployment of a new TB vaccine may impact on the rights and liberty of the individual.

BACKGROUND:Tuberculin skin tests (TSTs) are long-established screening methods for tuberculosis (TB). We aimed to compare agreement between the intradermal Mantoux and multipuncture percutaneous Tine methods and to quantify risk factors for a positive test result.METHODOLOGY/PRINCIPAL FINDINGS:1512 South African children younger than 5 years of age who were investigated for tuberculosis (TB) during a Bacille Calmette Guerin (BCG) trial were included in this analysis. Children underwent both Mantoux and Tine tests. A positive test was defined as Mantoux >or=15 mm or Tine >or= Grade 3 for the binary comparison. Agreement was evaluated using kappa (binary) and weighted kappa (hierarchical). Multivariate regression models identified independent risk factors for TST positivity. The Mantoux test was positive in 430 children (28.4%) and the Tine test in 496 children (32.8%, p<0.0001), with observed binary agreement 87.3% (kappa 0.70) and hierarchical agreement 85.0% (weighted kappa 0.66). Among 173 children culture-positive for Mycobacterium tuberculosis, Mantoux was positive in 49.1% and Tine in 54.9%, p<0.0001 (kappa 0.70). Evidence of digit preference was noted for Mantoux readings at 5 mm threshold intervals. After adjustment for confounders, a positive culture, suggestive chest radiograph, and proximity of TB contact were risk factors for a positive test using both TST methods. There were no independent associations between ethnicity, gender, age, or over-crowding, and TST result.CONCLUSIONS/SIGNIFICANCE:The Tine test demonstrated a higher positive test rate than the Mantoux, with substantial agreement between TST methods among young BCG-vaccinated children. TB disease and exposure factors, but not demographic variables, were independent risk factors for a positive result using either test method. These findings suggest that the Tine might be a useful screening tool for childhood TB in resource-limited countries.

The only currently licensed tuberculosis (TB) vaccine, bacille Calmette Guérin , confers incomplete protection against tuberculosis, and is not safe in infants infected with the human immunodeficiency virus. A new, safe vaccine regimen, which better protects against lung disease, is urgently needed to control TB in high-burden countries. Multiple candidate vaccines have shown promise in preclinical studies , and are now entering phase 1 to 2B clinical trials . This article discusses progress in the field and issues surrounding safety, reactogenicity, immunogenicity , and efficacy testing of new TB vaccines.

Objectives: To compare the diagnostic yield of Mycobacterium tuberculosis from induced sputum (IS) and gastric lavage (GL) among children in a community setting.Methods: Specimen-collection methods for bacteriological confirmation of pulmonary tuberculosis (PTB) were compared during a tuberculosis vaccine trial near Cape Town, South Africa (2001-2006). Children with a tuberculosis contact or compatible symptoms were investigated for suspected PTB. Diagnostic yields from 764 paired IS and GL specimens were compared in 191 culture-confirmed cases.Measurements and main results: The crude yield of M tuberculosis was 10.4%, n=108 by IS (5.8%) and n=127 by GL (6.8%), from a total of 194 cases, of which three had incomplete IS/GL specimen pairs. Agreement between IS and GL was poor (kappa=0.31). The comparative yield of a single IS sample (38%) was equivalent to a single GL sample (42%), with a difference in yield of 24% (95% CI -15% to + 7%). The combined yield of same-day IS and GL specimens (67%) was equivalent to two consecutive GL specimens (66%), with a difference in yield of 1% (95% CI -9% to 11%), but significantly greater than two consecutive IS specimens (55%), with a difference in yield of 12% (95% CI 2% to 21%). The adjusted odds of a M tuberculosis culture were increased by a positive tuberculin skin test or chest radiograph compatible with PTB.Conclusions: In this community setting, the diagnostic yield of a single IS sample was equivalent to that of a single GL sample. The optimal diagnostic yield may be obtained from paired IS and GL specimens taken on a single day or two GL specimens taken on consecutive days.

BACKGROUNDThe efficacy of bacille Calmette-Guérin (BCG) may be enhanced by heterologous vaccination strategies that boost the BCG-primed immune response. One leading booster vaccine, MVA85A (where "MVA" denotes "modified vaccinia virus Ankara"), has shown promising safety and immunogenicity in human trials performed in the United Kingdom. We investigated the safety and immunogenicity of MVA85A in mycobacteria-exposed--but Mycobacterium tuberculosis-uninfected--healthy adults from a region of South Africa where TB is endemic.METHODSTwenty-four adults were vaccinated with MVA85A. All subjects were monitored for 1 year for adverse events and for immunological assessment.RESULTSMVA85A vaccination was well tolerated and induced potent T cell responses, as measured by interferon (IFN)-gamma enzyme-linked immunospot assay, which exceeded prevaccination responses up to 364 days after vaccination. BCG-specific CD4+ T cells boosted by MVA85A were comprised of multiple populations expressing combinations of IFN-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and IL-17, as measured by polychromatic flow cytometry. IFN-gamma-expressing and polyfunctional IFN-gamma+TNF-gamma+IL-2+ CD4+ T cells were boosted during the peak BCG-specific response, which occurred 7 days after vaccination.CONCLUSIONThe excellent safety profile and quantitative and qualitative immunogenicity data strongly support further trials assessing the efficacy of MVA85A as a boosting vaccine in countries where TB is endemic.TRIAL REGISTRATIONClinicalTrials.gov identifier: NCT00460590.