Elevated serum 25-hydroxy (OH) vitamin D levels are associated with risk of TB progression in Gambian adults

SummaryBackgroundVitamin D is essential in the host defence against tuberculosis (TB) as an immune modulator. The aim of this study was to determine the level of 25-hydroxyvitamin D (25 (OH) D) from adult TB index cases before and after treatment and their exposed household contacts (HHC) in The Gambia.MethodsSerum from adult index TB cases and their TB-exposed household contacts (HHC) was analysed for 25(OH) D and Vitamin D binding protein (VDBP) concentrations. Tuberculin skin test (TST) status was used as a measure of Mycobacterium tuberculosis (Mtb) infectivity in the HHC. In addition, HHC who later progressed to active TB (incident cases) were assessed alongside non-progressors to determine the influence of 25 (OH) D levels on TB risk.ResultsEighty-three TB cases, 46 TST+ and 52 TST− HHC were analysed. Generally levels of 25(OH) D were considered insufficient in all subjects. However, median levels of 25(OH) D and VDBP were significantly higher in TB cases compared to both TST+ and TST− HHC at recruitment and were significantly reduced after TB therapy (p < 0.0001 for all). In addition, levels of serum 25(OH) D at recruitment were significantly higher in TB progressors compared to non-progressors (median (IQR): 25.0(20.8–29.2) in progressors and 20.3 (16.3–24.6) ng/ml in non-progressors; p = 0.007).ConclusionIn The Gambia, an equatorial country, 25(OH) D levels are higher in serum of TB progressors and those with active disease compared to latently infected and uninfected subjects. These results contrast to findings in non-equatorial countries

Immunogenicity of pneumococcal conjugate vaccine formulations containing pneumococcal proteins, and immunogenicity and reactogenicity of co-administered routine vaccines - A phase II, randomised, observer-blind study in Gambian infants.

BACKGROUND: Two conserved pneumococcal proteins, pneumolysin toxoid (dPly) and pneumococcal histidine triad protein D (PhtD), combined with 10 polysaccharide conjugates from the pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) in two investigational pneumococcal vaccine (PHiD-CV/dPly/PhtD) formulations were immunogenic and well-tolerated when administered to Gambian children. Here, we report immunogenicity of the polysaccharide conjugates, and immunogenicity and reactogenicity of co-administered routine vaccines. METHODS: In this phase II, controlled, observer-blind, single-centre study, healthy infants aged 8-10 weeks were randomised (1:1:1:1:1:1) to six groups. Four groups received 3+0 schedule (2-3-4 months [M]) of PHiD-CV/dPly/PhtD (10 or 30 µg of each protein), PHiD-CV, or 13-valent pneumococcal conjugate vaccine; and two groups received 2+1 schedule (2-4-9 M) of PHiD-CV/dPly/PhtD (30 µg of each protein) or PHiD-CV. All infants received diphtheria-tetanus-whole cell pertussis-hepatitis B-Haemophilus influenzae type b (DTPw-HBV/Hib) and oral trivalent polio vaccines (OPV) at 2-3-4 M, and measles, yellow fever, and OPV vaccines at 9 M. We evaluated immune responses at 2-5-9-12 M; and reactogenicity 0-3 days post-vaccination. RESULTS: 1200 infants were enrolled between June 2011 and May 2012; 1152 completed the study. 1 M post-primary vaccination, for each PHiD-CV serotype except 6B and 23F, ≥97.4% (3+0 schedule) and ≥96.4% (2+1 schedule) of infants had antibody concentrations ≥0.2 μg/mL. Immune responses were comparable between groups within the same vaccination schedules. Observed antibody geometric mean concentrations (GMCs) increased by 1 M post-primary vaccination compared to pre-vaccination. In the following months, GMCs and opsonophagocytic activity titres waned, with an increase post-booster for the 2+1 schedule. Immune responses to protein D and, DTPw-HBV/Hib, OPV, measles, and yellow fever vaccines were not altered by co-administration with pneumococcal proteins. Reactogenicity of co-administered vaccines was comparable between groups and did not raise concerns. CONCLUSION: Immune responses to the 10 PHiD-CV polysaccharide conjugates and co-administered vaccines were not altered by addition of dPly and PhtD. ClinicalTrials.gov identifier NCT01262872

Safety and immunogenicity of the candidate tuberculosis vaccine MVA85A in West Africa.

BACKGROUND: Vaccination with a recombinant modified vaccinia Ankara expressing antigen 85A from Mycobacterium tuberculosis, MVA85A, induces high levels of cellular immune responses in UK volunteers. We assessed the safety and immunogenicity of this new vaccine in West African volunteers. METHODS AND FINDINGS: We vaccinated 21 healthy adult male subjects (11 BCG scar negative and 10 BCG scar positive) with MVA85A after screening for evidence of prior exposure to mycobacteria. We monitored them over six months, observing for clinical, haematological and biochemical adverse events, together with assessment of the vaccine induced cellular immune response using ELISPOT and flow cytometry. MVA85A was well tolerated with no significant adverse events. Mild local and systemic adverse events were consistent with previous UK trials. Marked immunogenicity was found whether individuals had a previous BCG scar or not. There was not enhanced immunogenicity in those with a BCG scar, and induced T cell responses were better maintained in apparently BCG-naïve Gambians than previously studied BCG-naïve UK vaccinees. Although responses were predominantly attributable to CD4+ T cells, we also identified antigen specific CD8+ T cell responses, in subjects who were HLA B-35 and in whom enough blood was available for more detailed immunological analysis. CONCLUSIONS: These data on the safety and immunogenicity of MVA85A in West Africa support its accelerated development as a promising booster vaccine for tuberculosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT00423839

Broad adaptive immune responses to M. tuberculosis antigens precede TST conversion in tuberculosis exposed household contacts in a TB-endemic setting.

BACKGROUND: The identification of Mycobacterium-tuberculosis (Mtb) infected individuals remains a challenge due to an insufficient understanding of immune responses detected with the current diagnostic tests for latent tuberculosis i.e. the tuberculin skin test (TST) or IFN-γ release assays (IGRAs) and an inability to distinguish infection stages with current immunologic assays. Further classification based on markers other than IFN-γ may help to define markers of early Mtb infection. METHODS: We assessed the TST status of Mtb-exposed household contacts at baseline and at 6 months. Contacts were classified into those with initial positive TST (TST+); those with baseline negative TST but TST conversion at 6 months (TST converters, TSTC) and those with persistently negative TST (PTST-). We assessed their short- and long-term immune responses to PPD and ESAT-6/CFP-10 (EC) via IFN-γ ELISPOT and a multiplex cytokine array in relation to TST status and compared them to those of TB cases to identify immune profiles associated with a spectrum of infection stages. RESULTS: After 1 and 6 days stimulation with EC, 12 cytokines (IFN-γ, IL-2, IP-10, TNF-α, IL-13, IL-17, IL-10, GMCSF, MIP-1β, MCP-3, IL-2RA and IL-1A) were not different in TSTC compared to TST+ suggesting that robust adaptive Mtb-specific immune responses precede TST conversion. Stratifying contacts by baseline IFN-γ ELISPOT to EC in combination with TST results revealed that IP-10 and IL-17 were highest in the group of TST converters with positive baseline ELISPOT, suggesting they might be markers for recent infection. CONCLUSION: We describe a detailed analysis of Mtb-specific biomarker profiles in exposed household contacts in a TB endemic area that provides insights into the dynamic immune responses to Mtb infection and may help to identify biomarkers for 'at-risk' populations beyond TST and IGRA

Seroepidemiology of Hepatitis B and C Virus Infections: A Five-Year Retrospective Study among Blood Donors in Saboba District in the Northern Region of Ghana

Background and Objectives. Chronic hepatitis B and C infections are capable of progressing to liver cirrhosis and hepatocellular carcinoma. Globally, it has been estimated that over 2 billion and 170 million people are living with hepatitis B and C infections, respectively. Ghana remains one of the highly endemic countries challenged by the continuous spread of these viral agents in Africa. This study was aimed at determining the seroprevalence and trend of Hepatitis B and C coinfections among blood donors in Saboba District of the Northern Region of Ghana. Methods. A five-year hospital-based retrospective study was carried out among 8605 blood donors comprising 8517 males and 88 females using data on blood donors from Saboba Assemblies of God Hospital located in the Saboba District in the Northern Region of Ghana from 2013 to 2017. Blood bank records on HBV and HCV potential blood donors who visited the hospital to donate blood were retrieved. Donor demographic details, i.e., age and gender, were also recovered. Donors who were registered to the hospital but were not residents of the Northern Region were excluded from the study. Donors with incomplete records were also excluded from the study. The data was managed using Microsoft Excel spreadsheet 2016 and analysed using GraphPad Prism statistical software. Results. The overall prevalence of asymptomatic viral hepatitis B and C infections in the general adult population was 9.59% (95% CI: 9.00-10.20) and 12.71% (95% CI: 12.00-13.40), respectively, with an HBV/HCV coinfection rate of 2.23% (95% CI: 1.90-2.60). The number of donors generally declined with advancement in years from 2038 (23.68%) since 2013 to as low as 1169 (13.59%) in 2016, except for 2017 where a sharp increase of 1926 (22.38%) was observed. The first and second highest proportions of donors fell within the age categories of 20-29 (51.53% (4434)) and 30-39 (32.90% (2831)) respectively. The seroprevalence rate of HBV, HCV, and HBV/HCV coinfection rates were generally higher among the female group than those observed among the male category. The year-to-year variation in HBV, HCV, and HBV/HCV infections was statistically significant. The highest year-to-year HBV seropositivity rate was 11.48% in the year 2013, while that for HCV and HBV/HCV coinfection was 16.24% and 5.85%, respectively, both documented in the year 2014. HBV and HBV/HCV coinfection rates were highest among donors aged <20 years old, while HCV seroprevalence was highest among donors aged 50-59 years old. Significantly higher odds of HBV/HCV coinfection (OR=5.2; 95% CI:3.3-8.1) was observed in the 2014 compared to the year 2013. Donors aged <20years were at higher risks of HBV and HBV/HCV coinfection rates compared to the other age groups. Conclusion. The seroprevalence of HBV and HCV among donors in the Saboba District of the Northern Region of Ghana is endemic. The HBV/HCV coinfection rate also raises serious concern owing to its high prevalence rate among the younger age. Intensive public health education coupled with mobile screening and mass vaccination of seronegative individuals is advised so as to help curb further spread of the infection and in effect help safeguard the health status of potential donors in the district

Interferon-gamma treatment kinetics among patients with active pulmonary tuberculosis

Introduction: Interferon-γ (IFN-γ) is essential for defence against Mycobacterium tuberculosis; however, levels in patients with active tuberculosis (TB) and changes during treatment have not been documented in our tuberculosis patients in Nigeria, hence this study has been carried out. Objective: To determine variations, treatment kinetics, and predictive value of IFN-γ levels during treatment of active tuberculosis. Design: Patients with pulmonary tuberculosis were recruited and subsequently followed up for 3 months during treatment with anti-TB. Peripheral blood was collected for IFN-γ assays, C-reactive protein and others followed by a Mantoux test. IFN-γ levels produced by stimulation with TB antigens were determined by ELISA and repeated measurement of IFN-γ were done at 1 and 3 months of anti-TB therapy. Chi Associations and correlations between IFN-γ were determined. Regression analysis was done to determine association between serial IFN-γ and treatment outcome. Results: We recruited 47 patients with active tuberculosis with a mean age of 34.8 ± 3.6 years and M:F ratio of 1.12:1. Six (11%) were HIV positive. The mean level of IFN-γ induced by TB antigens was 629 ± 114.1 pg/ml, higher for HIV-negative PTB patients compared with HIV-positive PTB patients, 609.78 ± 723.9 pg/ml and 87.88 ± 130.0 pg/ml, respectively, P-value = 0.000. The mean level of IFN-γ induced by TB antigen increased significantly from 629 ± 114.1 pg/ml to 1023.46 + 222.8 pg/ml, P-value = 0.03 and reduced to 272.3 ± 87.7 pg/ml by the third month on anti-TB drugs, P-value = 0.001. Negative correlation was observed between the mean of baseline and chest X-ray involvement, P = 0.03. There was no significant correlation between sputum smear grade with baseline and follow-up IFN-γ levels. Three-month IFN-γ level among cured patients were higher than those with treatment failure, regression analysis showed that it does not predict outcome. Conclusion: IFN-γ may be useful in early detection and monitoring response; however, large scale studies are needed

Increased expression of mRNA encoding interleukin (IL)-4 and its splice variant IL-4δ2 in cells from contacts of Mycobacterium tuberculosis, in the absence of in vitro stimulation

Expression of interleukin (IL)-4 is increased in tuberculosis and thought to be detrimental. We show here that in healthy contacts there is increased expression of its naturally occurring antagonist, IL-4delta2 (IL-4δ2). We identified contacts by showing that their peripheral blood mononuclear cells (PBMC) released interferon (IFN)-γ in response to the Mycobacterium tuberculosis-specific antigen 6 kDa early secretory antigenic target (ESAT-6). Fresh unstimulated PBMC from these contacts contained higher levels of mRNA encoding IL-4δ2 (P = 0·002) than did cells from ESAT-6 negative donors (noncontacts). These data indicate that contact with M. tuberculosis induces unusual, previously unrecognized, immunological events. We tentatively hypothesize that progression to active disease might depend upon the underlying ratio of IL-4 to IL-4δ2

Mycobacterium tuberculosis Infection in Close Childhood Contacts of Adults with Pulmonary Tuberculosis is Increased by Secondhand Exposure to Tobacco.

Tobacco use is a major risk factor for tuberculosis (TB). Secondhand smoke (SHS) is also a risk factor for TB and to a lesser extent, Mycobacterium tuberculosis infection without disease. We investigated the added risk of M. tuberculosis infection due to SHS exposure in childhood contacts of TB cases in The Gambia. Participants were childhood household contacts aged ≤ 14 years of newly diagnosed pulmonary TB (PTB) cases. The intensity of exposure to the case was categorized according to whether contacts slept in the same room, same house, or a different house as the case. Contacts were tested with an enzyme-linked immunospot interferon gamma release assay. In multivariate regression models, M. tuberculosis infection was associated with increasing exposure to a case (odds ratios [OR]: 3.9, 95% confidence interval [CI]: 2.11-71.4, P < 0.001]) and with male gender (OR: 1.5 [95% CI: 1.12-2.11], P = 0.008). Tobacco use caused a 3-fold increase in the odds of M. tuberculosis infection in children who slept closest to a case who smoked within the same home compared with a nonsmoking case (OR: 8.0 [95% CI: 2.74-23.29] versus 2.4 [95% CI: 1.17-4.92], P < 0.001). SHS exposure as an effect modifier appears to greatly increase the risk of M. tuberculosis infection in children exposed to PTB cases. Smoking cessation campaigns may be important for reducing transmission of M. tuberculosis to children within households

Early clinical trials with a new tuberculosis vaccine, MVA85A, in tuberculosis-endemic countries: issues in study design.

Tuberculosis remains a substantial global health problem despite effective drug treatments. The efficacy of BCG, the only available vaccine, is variable, especially in tuberculosis-endemic regions. Recent advances in the development of new vaccines against tuberculosis mean that the first of these are now entering into early clinical trials. A recombinant modified vaccinia virus Ankara expressing a major secreted antigen from Mycobacterium tuberculosis, antigen 85A, was the first new tuberculosis vaccine to enter into clinical trials in September 2002. This vaccine is known as MVA85A. In a series of phase I clinical trials in the UK, MVA85A had an excellent safety profile and was highly immunogenic. MVA85A was subsequently evaluated in a series of phase I trials in The Gambia, a tuberculosis-endemic area in west Africa. This vaccine is the only new subunit tuberculosis vaccine to enter into clinical trials in Africa to date. Here, we discuss some of the issues that were considered in the protocol design of these studies including recruitment, inclusion and exclusion criteria, reimbursement of study participants, and HIV testing. These issues are highly relevant to early clinical trials with all new tuberculosis vaccines in the developing world

Cytokine/chemokine responses in TB cases and household contacts stratified by TST status after stimulation with ESAT^-6/CFP^-10 (EC) at enrolment.

<p>Following overnight or 6 day culture of peripheral blood mononuclear cells with EC, supernatants were collected and multiplex cytokine assays performed. Geometric mean levels are shown (pg/ml) A: Heat map showing geometric mean levels of different analytes after overnight (D1) versus 6 day (D6) culture in cases and contacts based on TST phenotype. The highest geometric means are shaded in red and the lowest in blue. Contacts were categorized according to TST scores at baseline and 6 months: TST⁺ = TST positive: TST≥10 mm at baseline; TSTC = TST converters: TST<10 mm at baseline and TST≥10 mm plus an increase in induration of at least 6 mm by 6 month; PTST⁻: persistently TST negative: TST<10 mm at both time–points. B: Heat map showing geometric mean levels of different analytes after overnight (D1) and 6 day (D6) culture in contacts grouped according to TST status and baseline EC IFN⁻γ ELISPOT (ECS) results. The highest geometric means are shaded in red and the lowest in blue.</p