Comparative analysis of tuberculin and defined antigen skin tests for detection of bovine tuberculosis in buffaloes (Bubalus bubalis) in Haryana state, India.

BACKGROUND: Bovine tuberculosis (bTB) is a chronic disease that results from infection with any member of the Mycobacterium tuberculosis complex. Infected animals are typically diagnosed with tuberculin-based intradermal skin tests according to World Organization of Animal Health which are presently in use. However, tuberculin is not suitable for use in BCG-vaccinated animals due to a high rate of false-positive reactions. Peptide-based defined skin test (DST) antigens have been identified using antigens (ESAT-6, CFP-10 and Rv3615c) which are absent from BCG, but their performance in buffaloes remains unknown. To assess the comparative performance of DST with the tuberculin-based single intradermal test (SIT) and the single intradermal comparative cervical test (SICCT), we screened 543 female buffaloes from 49 organized dairy farms in two districts of Haryana state in India. RESULTS: We found that 37 (7%), 4 (1%) and 18 (3%) buffaloes were reactors with the SIT, SICCT and DST tests, respectively. Of the 37 SIT reactors, four were positive with SICCT and 12 were positive with the DST. The results show that none of the animals tested positive with all three tests, and 6 DST positive animals were SIT negative. Together, a total of 43 animals were reactors with SIT, DST, or both, and the two assays showed moderate agreement (Cohen's Kappa 0.41; 95% Confidence Interval (CI): 0.23, 0.59). In contrast, only slight agreement (Cohen's Kappa 0.18; 95% CI: 0.02, 0.34) was observed between SIT and SICCT. Using a Bayesian latent class model, we estimated test specificities of 96.5% (95% CI, 92-99%), 99.7% (95% CI: 98-100%) and 99.0% (95% CI: 97-100%) for SIT, SICCT and DST, respectively, but considerably lower sensitivities of 58% (95% CI: 35-87%), 9% (95% CI: 3-21%), and 34% (95% CI: 18-55%) albeit with broad and overlapping credible intervals. CONCLUSION: Taken together, our investigation suggests that DST has a test specificity comparable with SICCT, and sensitivity intermediate between SIT and SICCT for the identification of buffaloes suspected of tuberculosis. Our study highlights an urgent need for future well-powered trials with detailed necropsy, with immunological and microbiological profiling of reactor and non-reactor animals to better define the underlying factors for the large observed discrepancies in assay performance, particularly between SIT and SICCT.

Harmonin homology domain-mediated interaction of RTEL1 helicase with RPA and DNA provides insights into its recruitment to DNA repair sites.

The regulator of telomere elongation helicase 1 (RTEL1) plays roles in telomere DNA maintenance, DNA repair, and genome stability by dismantling D-loops and unwinding G-quadruplex structures. RTEL1 comprises a helicase domain, two tandem harmonin homology domains 1&2 (HHD1 and HHD2), and a Zn2+-binding RING domain. In vitro D-loop disassembly by RTEL1 is enhanced in the presence of replication protein A (RPA). However, the mechanism of RTEL1 recruitment at non-telomeric D-loops remains unknown. In this study, we have unravelled a direct physical interaction between RTEL1 and RPA. Under DNA damage conditions, we showed that RTEL1 and RPA colocalise in the cell. Coimmunoprecipitation showed that RTEL1 and RPA interact, and the deletion of HHDs of RTEL1 significantly reduced this interaction. NMR chemical shift perturbations (CSPs) showed that RPA uses its 32C domain to interact with the HHD2 of RTEL1. Interestingly, HHD2 also interacted with DNA in the in vitro experiments. HHD2 structure was determined using X-ray crystallography, and NMR CSPs mapping revealed that both RPA 32C and DNA competitively bind to HHD2 on an overlapping surface. These results establish novel roles of accessory HHDs in RTEL1's functions and provide mechanistic insights into the RPA-mediated recruitment of RTEL1 to DNA repair sites.

Immunogenicity of PE18, PE31, and PPE26 proteins from Mycobacterium tuberculosis in humans and mice.

Introduction: The large family of PE and PPE proteins accounts for as much as 10% of the genome of Mycobacterium tuberculosis. In this study, we explored the immunogenicity of three proteins from this family, PE18, PE31, and PPE26, in humans and mice. Methods: The investigation involved analyzing the immunoreactivity of the selected proteins using sera from TB patients, IGRA-positive household contacts, and IGRA-negative BCG vaccinated healthy donors from the TB endemic country Mozambique. Antigen-recall responses were examined in PBMC from these groups, including the evaluation of cellular responses in healthy unexposed individuals. Moreover, systemic priming and intranasal boosting with each protein, combined with the Quil-A adjuvant, were conducted in mice. Results: We found that all three proteins are immunoreactive with sera from TB patients, IGRA-positive household contacts, and IGRA-negative BCG vaccinated healthy controls. Likewise, antigen-recall responses were induced in PBMC from all groups, and the proteins stimulated proliferation of peripheral blood mononuclear cells from healthy unexposed individuals. In mice, all three antigens induced IgG antibody responses in sera and predominantly IgG, rather than IgA, responses in bronchoalveolar lavage. Additionally, CD4+ and CD8+ effector memory T cell responses were observed in the spleen, with PE18 demonstrating the ability to induce tissue-resident memory T cells in the lungs. Discussion: Having demonstrated immunogenicity in both humans and mice, the protective capacity of these antigens was evaluated by challenging immunized mice with low-dose aerosol of Mycobacterium tuberculosis H37Rv. The in vitro Mycobacterial Growth Inhibition Assay (MGIA) and assessment of viable bacteria in the lung did not demonstrate any ability of the vaccination protocol to reduce bacterial growth. We therefore concluded that these three specific PE/PPE proteins, while immunogenic in both humans and mice, were unable to confer protective immunity under these conditions.

Diagnostic accuracy of immunological methods in patients with tuberculous pleural effusion from Venezuela / Precisión diagnóstica de métodos inmunológicos en pacientes con tuberculosis pleural de Venezuela

In recent years, better diagnostics for tuberculosis (TB) has received increasing attention, especially the diagnosis of tuberculous pleural effusion, which is difficult and at present the main tool in TPE diagnostic is pleural effusion smear and culture, but unfortunately, sensitivities are low, therefore better TPE diagnostic tools are needed. The aim of this study was to find a diagnostic algorithm to assess the progress in TPE diagnostic at the Hospital Vargas de Caracas, that permits identification of the majority of patients, at a satisfactory cost-benefit ratio, evaluating the levels of IFN-g and IL-12p40 in pleural effusion and serum, as well as the antibody reactivity in order to compare it with microbiological tests. A total of 60 individuals with pleural effusion were studied; 20 patients with tuberculous pleural effusion (TPE) formed the patient group and 40 patients with non-tuberculous pleural effusion (NTPE) formed the control group. The levels of IFN-g and IL-12p40 in effusion and serum and class and subclasses of IgG reactivity to Mycobacterium tuberculosis antigens were measured by ELISA. The utility of these methods for diagnosis of TPE was evaluated using receiver operating characteristic (ROC) curve analysis. The results of the 11 immunological methods evaluated showed that the anti-PPD IgG2 method was able to reach the highest specificity of 95% (CI: 88.3-101.8), positive predictive value (PPV)=75 (at 30% sensitivity); while that the overall sensitivity of methods was between 95% and 30%, of these, two methods reached higher sensitivities; increased levels of pleural IFN-g, with a sensitivity of 95% (CI: 85.5-104.5) with the highest negative predictive value (NPV)=97, (at 82.5% specificity), followed by decreased levels of serum IL-12p40 with a sensitivity of 95% (CI: 85.5-104.5), NPV=95.2 (at 50% specificity). In contrast, microbiological methods showed that smear had a sensitivity of only 20%, while smear plus ...

Recientemente existe un gran interés hacia un mejor y más rápido diagnóstico de tuberculosis (TB), especialmente de tuberculosis pleural, el cual es difícil. Al presente las principales herramientas diagnósticas son la baciloscopia y el cultivo de líquido pleural; desafortunadamente, las sensibilidades de estos métodos son bajas, por lo que el desarrollo de nuevas herramientas diagnósticas es necesario. El objetivo del presente estudio consistió en encontrar un algoritmo que permita la rápida identificación de la mayoría de los pacientes con TB pleural que ingresan en el Hospital Vargas de Caracas a un buen costo-beneficio. Para esto se evaluaron los niveles de las citocinas Interferón-gamma (IFN-g) y la Interleucina 12p40 (IL-12p40) en líquido pleural y suero, así como la reactividad de anticuerpos contra antígenos de Mycobacterium tuberculosis. Se estudiaron 60 individuos con derrame pleural; 20 individuos con líquido pleural tuberculoso (LPT) conformaron el grupo de pacientes y 40 individuos con líquido pleural no tuberculoso (LPNT) el grupo de controles. La técnica de inmunoensayo de ELISA fue utilizada para medir los niveles de IFN-g y IL-12p40; así como las reactividades de los diversos isotipos y subclases de inmunoglobulina G (IgG) frente a antígenos del bacilo. La utilidad de los métodos fue evaluada utilizando el análisis de las curvas ROC (receiver operating characteristic). Los resultados de los 11 métodos inmunológicos evaluados mostraron que el método IgG2 anti-PPD alcanzó la mayor especificidad de 95%, (CI: 88,3-101,8) con un valor predictivo positivo (VPP) de 75. La sensibilidad de los métodos estuvo entre 30% y 95%; dos métodos alcanzaron altas sensibilidades: los altos niveles de IFN-g en líquido pleural, con sensibilidad de 95% (CI: 85,5-104,5), con un valor predictivo negativo (VPN) de 97, seguido de los bajos niveles de IL-12p40 en suero, con una sensibilidad de 95% (CI: 85,5-104,5) con un VPN de 95,2. En contraste, ...

Evaluation of Lionex TB kits and mycobacterial antigens for IgG and IgA detection in cerebrospinal fluid from tuberculosis meningitis patients

To evaluate commercial Lionex TB together with four antigens of Mycobacterium tuberculosis (MPT-64, MT10.3, 16 kDa and 38 kDa) for IgG and IgA cerebrospinal fluid (CSF) detection in the diagnosis of tuberculosis meningitis (TBM) with CSF negative acid-fast bacilli staining, 19 cases of TBM, 64 cases of other infectious meningoencephalitis and 73 cases of other neurological disorders were tested by enzyme linked immunosorbent assay. IgA-MPT-64 and IgG Lionex showed the highest sensitivities, specificities, positive predictive value and negative predictive value (63.2 percent, 47.4 percent; 95 percent, 93.7 percent; 40 percent, 98 percent and 28.4 percent, 97.1 percent, respectively). However, while grey zone was 12.7 percent and 6 percent, respectively, lowering sensitivity but maintains high specificity (> 95 percent). High protein concentration in CSF was associated with antibody positivity CSF/HIV+ which did not influence the sensitivity of both tests. To our knowledge, this is the first description of IgA-MPT-64 and IgG Lionex antibodies in CSF-TBM and, although there is good specificity, adjustments are needed based on antigen composition to enhance sensitivity.

Comparison of serological responses in two different populations with pulmonary tuberculosis

Observational studies on the humoural immune responses of the Warao indigenous people from Delta Amacuro, an isolated area, were compared with urban residents of the Venezuelan capital. Mycobacterium tuberculosis-specific reactivities (IgM, IgE, sIgA, IgG and IgG subclasses) were measured by ELISA using PPD and 38-kDa M. tuberculosis antigens. A total of 294 individuals were studied, 162 Warao (indigenous people) and 132 Creole (non-indigenous people). The patient group consisted of 87 Warao patients and 58 Creole patients, while the control group consisted of 75 Warao controls and 74 Creole controls. Combinations among the isotypes studied were performed. The findings showed that for the Warao people, sensitivity to the combination including anti-PPD IgG and IgE was 92.0 percent, while for the Creole people, sensitivity to the combination including anti-PPD IgG but more so anti-PPD IgG1 and IgG2 was 90.0 percent. Simple tests were able to show higher specificities, which were population-specific; specificities were anti-PPD IgG3, 100.0 percent and anti-PPD IgM, 97.4 percent for the Warao and Creole peoples, respectively. In conclusion, while simple tests reached high specificity, the multi-isotype tests improved sensitivity; the latter shows this approach may be useful in diagnostic testing.

Serodiagnosis of tuberculosis: specific detection of free and complex-dissociated antibodies anti-mycobacterium tuberculosis recombinant antigens

The diagnostic test characteristics of detecting free and complex-dissociated IgG to three recombinant antigens of Mycobacterium tuberculosis (38-kDa, Ag16 and Ag85B), singly and in combination, were evaluated in sera from 161 tuberculous patients [smear-positive pulmonary TB (50), smear-negative pulmonary TB (pTBsm-) (60) and extrapulmonary TB (51)) and 214 control patients (mycobacteriosis (14), mycoses(14), leprosy(4), other underlying diseases (82) and healthy people (100)]. The individual antigens ranged from 25 percent to 42 percent in sensitivity and from 93 percent to 96 percent in specificity, while considering free IgG response. Addition of complex-dissociated antibodies against each individual antigen improved the sensitivity up to 55 percent. The number and levels of specific antibodies varied greatly from individual to individual. Combination of individual results for free and complex-dissociated IgG to 38-kDa, Ag16 and Ag85B offered 76 percent sensitivity and 83 percent specificity. When the three antigens were placed in the same well, the sensitivity was lower than that expected on the basis of single antigen (63 percent) but with a good specificity (95 percent), even in the group of mycobacteriosis or mycoses. The highest contribution of complex-dissociated IgG results to free IgG results was seen for the diagnosis of pTBsm- patients. In conclusion, although neither single recombinant antigen was reactive with most sera from TB patients even after the measurement of both free and complex-dissociated antibodies, the use of multi-antigen cocktails improved the diagnostic utility of the ELISA assay, allowing the identification of almost 70 percent of pTBsm-, with a high level of specificity; the use of additional, well selected antigens should lead to the detection of almost all patients with TB.

Cell proliferation and interferon-gamma response to recombinant MBP-3, NarL, MT-10.3, and 16kDa Mycobacterium tuberculosis antigens in Brazilian tuberculosis patients

Human pulmonary tuberculosis (TB) is a worldwide public health problem. In resistant individuals, control of the infection mainly requires development of a Th1 cell immune response with production of cytokines, of which interferon-gamma (IFN-gamma)plays an important role. Several antigens from Mycobacterium tuberculosis complex has been described for use in vaccine development or for diagnostic purposes, however little evaluation has been done in endemic area for TB. The proliferative and IFN-gamma human T cell immune responses, to four recombinant proteins (MBP-3, NarL, MT-10.3, 16 kDa) and PPD, of 38 Brazilian TB patients (6 untreated and 32 treated) and 67 controls (38 positive and 29 negative tuberculin skin test - TST) were compared. The highest reactivity mean rate was obtained with PPD followed by 16 kDa in TB patients. While most of the patients (87 percent) and controls (> 64 percent) respond to the PPD, 16kDa was more specifically recognized (> 21 percent) although less sensitive (54 percent). When TB patients were divided according to treatment status, opposite to PPD, higher average level of IFN-gamma was induced by 16kDa in untreated (505 pg/ml) compared to treated TB patients and TST+ (269.8 pg/ml x 221.6pg/ml, respectively), although the difference was not significant. These data show that in contrast with the other recombinant proteins, the stimulatory potency of 16kDa to induce proliferative and INF-gamma response was more effective and is more recognized by active TB untreated patients, eliciting in control individuals a more selective immune response than PPD.