Dataset Information

Clinical and diagnostic developments of a gamma interferon release assay for use in bovine tuberculosis control programs.

ABSTRACT: Currently, the Bovigam assay is used as an official supplemental test within bovine tuberculosis control programs. The objectives of the present study were to evaluate two Mycobacterium bovis-specific peptide cocktails and purified protein derivatives (PPDs) from two sources, liquid and lyophilized antigen preparations. PPDs and peptide cocktails were also used for comparison of a second-generation gamma interferon (IFN-?) release assay kit with the currently licensed first-generation kit (Bovigam; Prionics AG). Three strains of M. bovis were used for experimental challenge: M. bovis 95-1315, M. bovis Ravenel, and M. bovis 10-7428. Additionally, samples from a tuberculosis-affected herd (i.e., naturally infected) were evaluated. Robust responses to both peptide cocktails, HP (PC-HP) and ESAT-6/CFP10 (PC-EC), and the PPDs were elicited as early as 3 weeks after challenge. Only minor differences in responses to Commonwealth Serum Laboratories (CSL) and Lelystad PPDs were detected with samples from experimentally infected animals. For instance, responses to Lelystad M. avium-derived PPD (PPDa) exceeded the respective responses to the CSL PPDa in M. bovis Ravenel-infected and control animals. However, a 1:4 dilution of stimulated plasma demonstrated greater separation of PPDb from PPDa responses (i.e., PPDb minus PPDa) with the use of Lelystad PPDs, suggesting that Lelystad PPDs provide greater diagnostic sensitivity than CSL PPDs. The responses to lyophilized and liquid antigen preparations did not differ. Responses detected with first- and second-generation IFN-? release assay kits (Bovigam) did not differ throughout the study. In conclusion, antigens may be stored in a lyophilized state without loss in potency, PC-HP and PC-EC are dependable biomarkers for aiding in the detection of bovine tuberculosis, and second-generation Bovigam kits are comparable to currently used kits.

SUBMITTER: Bass KE

PROVIDER: S-EPMC3889511 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Clinical and diagnostic developments of a gamma interferon release assay for use in bovine tuberculosis control programs.

Bass K E KE Nonnecke B J BJ Palmer M V MV Thacker T C TC Hardegger R R Schroeder B B Raeber A J AJ Waters W R WR

Clinical and vaccine immunology : CVI 20131016 12

Currently, the Bovigam assay is used as an official supplemental test within bovine tuberculosis control programs. The objectives of the present study were to evaluate two Mycobacterium bovis-specific peptide cocktails and purified protein derivatives (PPDs) from two sources, liquid and lyophilized antigen preparations. PPDs and peptide cocktails were also used for comparison of a second-generation gamma interferon (IFN-γ) release assay kit with the currently licensed first-generation kit (Bovig ...[more]

PMID: 24132602

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Project description:National guidelines recommend screening for latent tuberculosis infection (LTBI) in all HIV-infected patients. Thus, the objective of this study was to measure protocol adherence to national guidelines regarding LTBI screening for HIV-infected patients entering care at an urban primary care clinic specializing in HIV care, identify clinical and other characteristics associated with adherence, and determine whether transitioning from the tuberculin skin test (TST) to the interferon-gamma release assay (IGRA) improved adherence. We conducted a retrospective study using protocol adherence to LTBI screening guidelines within twelve months of entering care at an HIV clinic as the primary outcome. Successful protocol adherence was defined as the placement and reading of a TST, performance of an IGRA, or a note in study clinic records documenting prior testing or treatment for tuberculosis in an outside setting. Multivariable modified Poisson regression models were used in analyses. Overall, 32% (n?=?118/372) of patients received LTBI screening within twelve months of entering care. Protocol adherence to LTBI screening guidelines increased from 28% to 37% following the transition from TST to IGRA screening. IGRA screening [adjusted prevalence ratio: 1.45, 95% confidence limits: (1.07, 1.96)], male sex [1.47 (1.05, 2.07)], transfer patient status [1.51 (1.05, 2.18)], and greater than one year of clinic attendance [1.62 (1.06, 2.48)] were independently associated with protocol adherence. Among patients without prior LTBI screening or treatment, patients entering the clinic in 2013 under the IGRA screening protocol were more likely to be screened for LTBI compared to patients entering under the TST screening protocol (34.3% vs. 9.7%, p?<?0.001). In conclusion, transitioning from TST to IGRA-based screening improved adherence to screening guidelines. However, further work on improving adherence to LTBI screening guidelines among HIV-infected patients is needed.

Project description:BackgroundWe evaluated the diagnostic and prognostic performance of a transcriptomic signature of tuberculosis (TB) risk (RISK11) and QuantiFERON-TB Gold-plus (QFTPlus) as combination biomarkers of TB risk.MethodsHealthy South Africans who were HIV-negative aged 18-60 years with baseline RISK11 and QFTPlus results were evaluated in a prospective cohort study conducted between Sept 20, 2016 and Dec 20, 2019. Prevalence and incidence-rate ratios were used to evaluate risk of TB. Positive (LR+) and negative (LR-) likelihood ratios were used to compare individual tests versus Both-Positive (RISK11+/QFTPlus+) and Either-Positive (RISK11+ or QFTPlus+) combinations.FindingsAmong 2912 participants, prevalent TB in RISK11+/QFTPlus+ participants was 13·3-fold (95% CI 4·2-42·7) higher than RISK11-/QFTPlus-; 2·4-fold (95% CI 1·2-4·8) higher than RISK11+/QFTPlus-; and 4·5-fold (95% CI 2·5-8·0) higher than RISK11-/QFTPlus+ participants. Risk of incident TB in RISK11+/QFTPlus+ participants was 8·3-fold (95% CI 2·5-27·0) higher than RISK11-/QFTPlus-; 2·5-fold (95% CI 1·0-6·6) higher than RISK11+/QFTPlus-; and 2·1-fold (95% CI 1·2-3·4) higher than RISK11-/QFTPlus+ participants, respectively. Compared to QFTPlus, the Both-Positive test combination increased diagnostic LR+ from 1·3 (95% CI 1·2-1·5) to 4·7 (95% CI 3·2-7·0), and prognostic LR+ from 1·4 (95% CI 1·2-1·5) to 2·8 (95% CI 1·5-5·1), but did not improve upon RISK11 alone. Compared with RISK11, the Either-Positive test combination decreased diagnostic LR- from 0·7 (95% CI 0·6-0·9) to 0·3 (95% CI 0·2-0·6), and prognostic LR- from 0·9 (95% CI 0·8-1·0) to 0·3 (0·1-0·7), but did not improve upon QFTPlus alone.InterpretationCombining two tests such as RISK11 and QFTPlus, with discordant individual performance characteristics does not improve overall discriminatory performance, relative to the individual tests.FundingBill and Melinda Gates Foundation, South African Medical Research Council.

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Project description:BackgroundAlthough persistent tuberculosis (TB) infection is known to cause calcification in the lungs, the relationship between intrathoracic calcification and the results of the interferon-γ release assay (IGRA) has not been fully elucidated. This study aimed to assess the association between intrathoracic calcification and IGRA results.MethodsWe retrospectively included consecutive patients who concurrently underwent chest X-ray, chest computed tomography (CT), and an IGRA. Patients with a current diagnosis of active TB or treatment history of active TB or latent tuberculosis infection (LTBI) were excluded. The association between calcification according to the chest X-ray or CT and IGRA results were analyzed using binomial logistic regression.ResultsThis study included 574 patients, and 38 (7%) patients had a positive IGRA result. Patients with a positive result were significantly older and had a higher proportion of comorbidities, and history of tuberculosis exposure compared to those with a negative result. Calcification of the lung field and mediastinal lymph nodes according to chest CT was more frequently observed in patients with a positive IGRA result, whereas no significant difference was observed concerning the proportion of lung field calcification on chest X-ray between patients with positive and negative IGRA results. In multivariate analysis, calcification of mediastinal lymph nodes alone (adjusted odds ratio [OR] = 3.82, 95% confidence interval [CI] = 1.76-8.26) and the combination of lung field and mediastinal lymph node calcification (adjusted OR = 4.12, 95% CI = 1.51-11.76) on chest CT was independently associated with positive IGRA results.ConclusionsThe finding of mediastinal lymph node calcification, with or without lung field calcification, on chest CT was associated with positive IGRA results independent of TB exposure history. Previous TB infection including eliminated TB infection and LTBI can be suspected when calcified lymph nodes in are observed the mediastinum on chest CT.

Dataset Information

Clinical and diagnostic developments of a gamma interferon release assay for use in bovine tuberculosis control programs.

Publications

Clinical and diagnostic developments of a gamma interferon release assay for use in bovine tuberculosis control programs.

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