Matthew K. O'Shea

T-cell activation is an immune correlate of risk in BCG vaccinated infants

Vaccines to protect against tuberculosis (TB) are urgently needed. We performed a case–control analysis to identify immune correlates of TB disease risk in Bacille Calmette–Guerin (BCG) immunized infants from the MVA85A efficacy trial. Among 53 TB case infants and 205 matched controls, the frequency of activated HLA-DR+ CD4+ T cells associates with increased TB disease risk (OR=1.828, 95% CI=1.25–2.68, P=0.002, FDR=0.04, conditional logistic regression). In an independent study of Mycobacterium tuberculosis-infected adolescents, activated HLA-DR+ CD4+ T cells also associate with increased TB disease risk (OR=1.387, 95% CI=1.068–1.801, P=0.014, conditional logistic regression). In infants, BCG-specific T cells secreting IFN-γ associate with reduced risk of TB (OR=0.502, 95% CI=0.29–0.86, P=0.013, FDR=0.14). The causes and impact of T-cell activation on disease risk should be considered when designing and testing TB vaccine candidates for these populations.

Symptomatic Respiratory Syncytial Virus Infection in Previously Healthy Young Adults Living in a Crowded Military Environment

BACKGROUND Respiratory syncytial virus (RSV) infection is a potentially important cause of acute respiratory illness in many populations, including military recruits receiving basic training. Understanding the full impact of RSV infection is challenging because of difficulties in diagnosis and the limitations of past epidemiologic studies. In this study, we set out to determine the prevalence and clinical characteristics of RSV infection and infection caused by other common viral agents in a population of previously healthy young adults, namely, military recruits receiving basic training. METHODS In addition to standard viral culture techniques, we employed serologic testing and a recently described, novel, highly sensitive real-time PCR and a molecular beacon probe assay for the detection of RSV infection. RESULTS Among 256 military trainees with respiratory symptoms, RSV infection was identified in 11% by means of serologic testing and real-time PCR. Viral culture identified adenovirus in 48% of symptomatic recruits, influenza viruses in 11%, parainfluenza virus 3 in 3%, and enterovirus in <1%. The majority of recruits with RSV infection experienced a nonproductive cough, sore throat, and nasal congestion, and almost half reported symptoms of wheeze or shortness of breath. Almost all (94%) of the recruits lost > or =1 day(s) from training because of illness. CONCLUSIONS This study demonstrates the challenges of diagnosis and clinical significance of RSV infection in symptomatic young adults. RSV may account for 11% of clinically important respiratory illnesses in this population, which is as much as 25% of previously undiagnosed illness. These results have implications for treatment and prevention of RSV in young adults.

Diagnosis of Febrile Illnesses other than Ebola Virus Disease at an Ebola Treatment Unit in Sierra Leone

Abstract Patients with febrile illnesses presenting to an Ebola treatment unit in Sierra Leone had a wide range of diagnoses other than Ebola virus disease. Rapid diagnostic tests were useful in confirming these diagnoses, reducing the length of patient stay with valuable consequences. These alternative diagnoses should assist in future planning.

Seroprevalence of Trypanosoma cruzi Among Mothers and Children in Rural Mayan Communities and Associated Reproductive Outcomes

Our objective was to determine the seroprevalence of Trypanosoma cruzi infection among mothers and children in two rural Mayan communities in Yucatan, Mexico and examine sociodemographic characteristics and adverse reproductive outcomes associated with maternal infection. We performed household surveys in the communities of Sudzal and Teya. Mothers were interviewed, and blood samples were obtained to perform rapid tests and enzyme-linked immunosorbent assays (ELISAs). We surveyed 390 mothers and 685 children. The overall seroprevalence was 2.3% among mothers and 0.4% among children. In Sudzal, we found a seroprevalence of 4.4% among mothers and 0.7% in children. In Teya, we found a seroprevalence of 0.9% among mothers and 0.3% among children. Compared with uninfected mothers, seropositive mothers reported more stillbirths (relative risk = 4.7; 95% confidence interval = 2.1-10.4). T. cruzi infection is present in these communities, and infected children indicate active transmission. Seropositivity in mothers is associated with a history of adverse reproductive outcomes.

Distinct Transcriptional and Anti-Mycobacterial Profiles of Peripheral Blood Monocytes Dependent on the Ratio of Monocytes: Lymphocytes.

The ratio of monocytes and lymphocytes (ML ratio) in peripheral blood is associated with tuberculosis and malaria disease risk and cancer and cardiovascular disease outcomes. We studied anti-mycobacterial function and the transcriptome of monocytes in relation to the ML ratio. Mycobacterial growth inhibition assays of whole or sorted blood were performed and mycobacteria were enumerated by liquid culture. Transcriptomes of unstimulated CD14+ monocytes isolated by magnetic bead sorting were characterised by microarray. Transcript expression was tested for association with ML ratio calculated from leucocyte differential counts by linear regression. The ML ratio was associated with mycobacterial growth in vitro (β=2.23, SE 0.91, p=0.02). Using sorted monocytes and lymphocytes, in vivo ML ratio (% variance explained R2=11%, p=0.02) dominated over in vitro ratios (R2=5%, p=0.10) in explaining mycobacterial growth. Expression of 906 genes was associated with the ML ratio and 53 with monocyte count alone. ML-ratio associated genes were enriched for type-I and -II interferon signalling (p=1.2×10-8), and for genes under transcriptional control of IRF1, IRF2, RUNX1, RELA and ESRRB. The ML-ratio-associated gene set was enriched in TB disease (3.11-fold, 95% CI: 2.28-4.19, p=5.7×10-12) and other inflammatory diseases including atopy, HIV, IBD and SLE. The ML ratio is associated with distinct transcriptional and anti-mycobacterial profiles of monocytes that may explain the disease associations of the ML ratio.The ratio of monocytes and lymphocytes (ML ratio) in peripheral blood is associated with tuberculosis and malaria disease risk and cancer and cardiovascular disease outcomes. We studied anti-mycobacterial function and the transcriptome of monocytes in relation to the ML ratio. Mycobacterial growth inhibition assays of whole or sorted blood were performed and mycobacteria were enumerated by liquid culture. Transcriptomes of unstimulated CD14 + monocytes isolated by magnetic bead sorting were characterised by microarray. Transcript expression was tested for association with ML ratio calculated from leucocyte differential counts by linear regression. The ML ratio was associated with mycobacterial growth in vitro (β = 2.23, SE 0.91, p = 0.02). Using sorted monocytes and lymphocytes, in vivo ML ratio (% variance explained R2 = 11%, p = 0.02) dominated over in vitro ratios (R2 = 5%, p = 0.10) in explaining mycobacterial growth. Expression of 906 genes was associated with the ML ratio and 53 with monocyte count alone. ML-ratio associated genes were enriched for type-I and -II interferon signalling (p = 1.2 × 10− 8), and for genes under transcriptional control of IRF1, IRF2, RUNX1, RELA and ESRRB. The ML-ratio-associated gene set was enriched in TB disease (3.11-fold, 95% CI: 2.28–4.19, p = 5.7 × 10− 12) and other inflammatory diseases including atopy, HIV, IBD and SLE. The ML ratio is associated with distinct transcriptional and anti-mycobacterial profiles of monocytes that may explain the disease associations of the ML ratio.

A review of clinical models for the evaluation of human TB vaccines

ABSTRACT While much progress has been made in the fight against the scourge of tuberculosis (TB), we are still some way from reaching the ambitious targets of eliminating it as a global public health problem by the mid twenty-first century. A new and effective vaccine that protects against pulmonary TB disease will be an essential element of any control strategy. Over a dozen vaccines are currently in development, but recent efficacy trial data from one of the most advanced candidates have been disappointing. Limitations of current preclinical animal models exist, together with a lack of a complete understanding of host immunity to TB or robust correlates of disease risk and protection. Therefore, in the context of such obstacles, we discuss the lessons identified from recent efficacy trials, current concepts of biomarkers and correlates of protection, the potential of innovative clinical models such as human challenge and conducting trials in high-incidence settings to evaluate TB vaccines in humans, and the use of systems vaccinology and novel technologies including transcriptomics and metabolomics, that may facilitate their utility.

Time-To-Detection in Culture Predicts Risk of Mycobacterium tuberculosis transmission: A Cohort Study

BACKGROUND Contact screening is an essential component of all tuberculosis control strategies. We hypothesize that time-to-detection (TTD) in liquid culture of spontaneously produced sputum samples may help identify index cases at high risk of transmission. METHODS We studied retrospectively a cohort of patients with pulmonary tuberculosis in Birmingham, United Kingdom (January 2010-December 2012). We studied the correlation of TTD with the risk of transmission of infection from index cases to contacts and compared this with sputum microscopy. Chest radiographs (CXRs) were graded from 0 to 6 (0, no radiographic evidence of disease; 5, bilateral cavitation; and 6, miliary disease). RESULTS Of the 184 cases of pulmonary tuberculosis reported during the study period, 111 were included in the final study, and these generated 825 contacts. A transmission event (new latent or active tuberculosis) was identified in 165 contacts (transmission rate 0.20). Short TTD (<9 days) was associated with an increased risk of transmission (odds ratio, 2.56; P < .001), and this relationship persisted after adjusting for potential confounders. A 1-point increase in CXR grade correlated with a 3.2-day decrease in TTD (P < .001), and this correlation persisted after adjustment for potential confounders. CONCLUSIONS TTD < 9 days identifies patients at high risk of transmitting tuberculosis and is superior to sputum smear. CXR grade at diagnosis predicts patients with short TTD. Our findings have the potential to guide the organization and prioritization of contact investigations in similar settings.

Tuberculin Skin Testing and Treatment Modulates Interferon-Gamma Release Assay Results for Latent Tuberculosis in Migrants

Background Identifying latent tuberculosis infection (LTBI) in people migrating from TB endemic regions to low incidence countries is an important control measure. However, no prospective longitudinal comparisons between diagnostic tests used in such migrant populations are available. Objectives To compare commercial interferon (IFN)-gamma release assays (IGRAs) and the tuberculin skin test (TST) for diagnosing LTBI in a migrant population, and the influence of antecedent TST and LTBI treatment on IGRA performance. Materials and Methods This cohort study, performed from February to September 2012, assessed longitudinal IGRA and TST responses in Nepalese military recruits recently arrived in the UK. Concomitant T-SPOT.TB, QFT-GIT and TST were performed on day 0, with IGRAs repeated 7 and 200 days later, following treatment for LTBI if necessary. Results 166 Nepalese recruits were prospectively assessed. At entry, 21 individuals were positive by T-SPOT.TB and 8 individuals by QFT-GIT. There was substantial agreement between TST and T-SPOT.TB positives at baseline (71.4% agreement; κ = 0.62; 95% CI:0.44–0.79), but only moderate concordance between positive IGRAs (38.1% agreement; κ = 0.46; 95% CI:0.25–0.67). When reassessed 7 days following TST, numbers of IGRA-positive individuals changed from 8 to 23 for QFT-GIT (p = 0.0074) and from 21 to 23 for T-SPOT.TB (p = 0.87). This resulted in an increase in IGRA concordance to substantial (64.3% agreement; κ = 0.73; 95% CI:0.58-0.88). Thus, in total on day 0 and day 7 after testing, 29 out of 166 participants (17.5%) provided a positive IGRA and of these 13 were TST negative. Two hundred days after the study commenced and three months after treatment for LTBI was completed by those who were given chemoprophylaxis, 23 and 21 participants were positive by T-SPOT.TB or QFT-GIT respectively. When individual responses were examined longitudinally within this population 35% of the day 7 QFT-GIT-positive, and 19% T-SPOT.TB-positive individuals, were negative by IGRA. When the change in the levels of secreted IFN-γ was examined after chemoprophylaxis the median levels were found to have fallen dramatically by 77.3% from a pre-treatment median concentration of IFN-γ 2.73 IU/ml to a post-treatment median concentration IFN-γ 0.62 (p = 0.0002). Conclusions This study suggests differences in the capacity of commercially available IGRAs to identify LTBI in the absence of antecedent TST and that IGRAs, in the time periods examined, may not be the optimal tests to determine the success of chemoprophylaxis for LTBI.

Respiratory infections in the military

Military training facilities and operational theatres, and the stressful activities undertaken in such settings, are unique. Military personnel living and working in these environments are at considerable risk of the acquisition and onward transmission of a variety of respiratory infections. While these generally cause mild illness, severe disease may occur with significant associated morbidity and, occasionally, mortality. Epidemic outbreaks among military personnel may have a significant detrimental impact on training schedules and operational effectiveness. The recognition of the burden of such illness among British military personnel, and the development of strategies required to prevent or limit negative impacts, can only be achieved through the use of comprehensive laboratory-based surveillance programmes.

A Health Care Worker with Ebola Virus Disease and Adverse Prognostic Factors Treated in Sierra Leone.

We describe the management of a Sierra Leonean health care worker with severe Ebola virus disease complicated by diarrhea, significant electrolyte disturbances, and falciparum malaria coinfection. With additional resources and staffing, high quality care can be provided to patients with Ebola infection and adverse prognostic factors in west Africa.