Interferon-gamma Release Assay Research Articles

HBHA-IGRA and cytotoxic mediators release assays for the diagnosis of cervical tuberculous lymphadenitis.

Cervical tuberculous lymphadenitis (CTL), the most frequent extrapulmonary form of tuberculosis, is a serious health problem in Tunisia. CTL diagnosis is challenging mainly due to the paucibacillary nature of the disease and the potential misdiagnosis as cervical non-tuberculous lymphadenitis (CNTL). Here, we evaluated the performance of heparin-binding hemagglutinin (HBHA) interferon-gamma (IFN-γ) release assay (IGRA) for the diagnosis of CTL. In addition, we evaluated granzyme B, granulysin, and perforin release assays as CTL biomarkers and assessed their potential contribution to improve HBHA-IGRA performance. Peripheral blood mononuclear cells from CTL-suspected patients were stimulated with HBHA, early secreted antigenic target 6 (ESAT-6), or purified protein derivative (PPD) for 24 h in the presence of IL-7. Cytotoxic mediators and IFN-γ release were assessed by enzyme-linked immunosorbent assay. Receiver operating characteristic curves were used to evaluate the capacity of HBHA, ESAT-6, and PPD to discriminate between CTL (n = 27) and CNTL (n = 21). After applying bivariate and multivariate analyses, IFN-γ responses to HBHA appeared to offer the best distinction between CTL and CNTL, with an area under the curve of 0.9947, associated with 95.24% and 100% sensitivity and specificity, respectively. A principal component analysis showed clear clustering of the CTL versus the CNTL groups. This clustering was mainly attributed to HBHA-induced IFN-γ, PPD-induced granzyme B, and PPD-induced IFN-γ. These results thus suggest that the HBHA-IGRA provides high diagnostic accuracy for CTL versus CNTL, with high sensitivity and specificity. Combining HBHA-induced IFN-γ and PPD-induced granzyme B improves the accuracy to identify CTL.IMPORTANCECervical tuberculous lymphadenitis (CTL), the most frequent extrapulmonary form of tuberculosis, is currently a major health problem in Tunisia and in several regions around the world. CTL diagnosis is challenging mainly due to the paucibacillary nature of the disease and the potential misdiagnosis as cervical non-tuberculous lymphadenitis. This study demonstrates the added value of the heparin-binding hemagglutinin-interferon-gamma release assay as an immunoassay in the context of CTL.

Right to Occupational Safety: Prevalence of Latent Tuberculosis Infection in Healthcare Workers. A 1-Year Retrospective Survey Carried out at Hospital of Lecce (Italy).

Prevention of latent tuberculosis infection (LTBI) in healthcare workers (HCWs) to ensure the "Right to Occupational Safety" is a special challenge globally, as HCWs have a higher risk of acquiring the infection in hospital settings because of frequent close exposure to patients suffering from tuberculosis (TB). Aretrospective study was performed with the aim of assessing the prevalence of LTBI related to demographical and occupational risk factors among HCWs employed in a large hospital in Italy. The study involved 1461 HCWs screened for LTBI by Mantoux tuberculin skin test (TST) and then confirmed with Interferon Gamma Release Assay (IGRA) test in case of positivity. Immunosuppressed and BGC-vaccinated workers were tested directly with IGRA. LTBI was diagnosed in 4.1% of the HCWs and the prevalence resulted lower than other studies conducted in low TB incidence countries. The variables significantly linked with higher frequency of the infection were: age ≥40 years (OR = 3.14; 95% CI: 1.13-8.74; p < 0.05), length of service ≥15 years (OR = 4.11; 95% CI: 1.48-11.43; p < 0.05) and not being trained on TB prevention (OR = 3.46; 95% CI: 1.85-6.46; p < 0.05). Not trained HCWs presented a higher risk of LTBI also after adjustment for age and length of service, compared to trained HCWs. screening of HCWs for LTBI should be always considered in routinely occupational surveillance in order to early diagnose the infection and prevent its progression. Safety policies in hospital settings centered on workers' training on TB prevention is crucial to minimize LTBI occurrence in HCWs.

Quantiferon in the Diagnosis of Tuberculosis

Quantiferon test (QFT) is an indirect diagnostic test for latent tuberculosis (TB) infection and active TB. Objectives: The aim of this study is to investigate the role of Quantiferon-TB Gold test as one of the interferon-gamma release assays (IGRAs) in detecting LTBI. Research Methodology: This study was conducted at private lab in Tripoli during the period from October 2022 to January 2023, Diagnosis of 254 sample recorded. QFT was performed in accordance with the manufacturer’s instructions. Results: The study include (n= 254 cases), (58 sample 22.8 %) show positive results by Quantiferon test while (196 sample 77.1%) show negative test. Females constituted 118 (46.4%) of the total cases, while the males constituted 136 (53.6%). the age (31-40 years) for the negative include (35 cases 13.7%) while (41-50 years and (61-70 years) for positive include (11cases 4.3%). Discussion: This study confirmed previous reports that the QFT test had greater sensitivity for detecting active TB than the 100-year-old TST. Conclusion: It was concluded that the quantiferon TB-2G test is a more useful diagnostic method for tuberculosis infection. QFT-Plus assay showed good sensitivity for active TB and was particularly useful for the evaluation of children with suspected LTBI, giving a low rate of indeterminate results in this group. More studies are needed to properly evaluate QFT-Plus ability in discriminating active disease from latent infection.

Negative conversion of T-SPOT results after hemodialysis: case series and literature review

BackgroundLatent tuberculosis infection (LTBI) affects 11.9% of outpatients under maintenance hemodialysis in Japan. In addition, the risk of reactivation of LTBI in hemodialysis patients is up to 10–25 times higher than that in the general population. Therefore, the accurate diagnosis and treatment for LTBI are extremely important. The interferon-γ release assays are widely used for screening LTBI; however, the impact of hemodialysis on the assay results has been uncertain.Case presentationTwenty-seven hemodialysis patients (17 males, 69.9 ± 10.1 year old) were performed T-SPOT®.TB test (T-SPOT) both before and after hemodialysis. In cases where T-SPOT results were different before and after hemodialysis, T-SPOT was re-evaluated in a same manner. As a result, two cases showed consistent T-SPOT diagnostic discrepancy before and after hemodialysis in two measurements. In the first case, T-SPOT was indeterminate/positive before hemodialysis, but changed to negative after hemodialysis. In the second case, T-SPOT was positive before hemodialysis, but changed to indeterminate after hemodialysis.ConclusionsWe experienced the negative conversion of T-SPOT after hemodialysis in cases of LTBI. T-SPOT may show false-negative when measured after hemodialysis due to immunomodulation caused by hemodialysis.

A Case Report of UDCA and &lt;italic&gt;Injinho-tang&lt;/italic&gt; Co-administration for Liver Damage Caused by Rifampin

We have experienced a case in which herbal medicine was administered to treat drug-induced liver damage and would like to introduce it. A 49-year-old man exhibited a positive result in the interferon-gamma release assay. He had never suffered from tuberculosis in the past, and the route and time of infection could not be confirmed. He had no respiratory or systemic symptoms suggestive of active tuberculosis, and a chest X-ray examination showed no active lung lesions, so he was diagnosed with latent tuberculosis infection. He was confirmed to be within the normal range in the liver function test, renal function test, and complete blood cell count test, and started taking rifampin (600 mg qd). In the screening test performed on the 19th day of taking the drug, other test items were normal, but alanine aminotransferase (ALT) increased to 50 U/L (reference value: 4-40 U/L). In a test performed on the 29th day of taking the drug, ALT was clearly elevated to 102 U/L. Ursodeoxycholic acid and &lt;i&gt;Injinho-tang&lt;/i&gt; were taken together with rifampin, and the patient’s progress was observed. In a test performed 14 days later, ALT decreased to 26 U/L, within the normal range. It is presumed that &lt;i&gt;Injinho-tang&lt;/i&gt; may have partially contributed to alleviating liver damage in this case.

Quantiferon in the Diagnosis of Tuberculosis

Quantiferon test (QFT) is an indirect diagnostic test for latent tuberculosis (TB) infection and active TB. Objectives: The aim of this study is to investigate the role of Quantiferon-TB Gold test as one of the interferon-gamma release assays (IGRAs) in detecting LTBI. Research methodology: This study was conducted at private lab in Tripoli during the period from October 2022 to January 2023, Diagnosis of 254 sample recorded. QFT was performed in accordance with the manufacturer’s instructions. Results: The study include (n= 254 cases), (58 sample 22.8 %) show positive results by Quantiferon test while (196 sample 77.1%) show negative test. Females constituted 118 (46.4%) of the total cases, while the males constituted 136 (53.6%). the age (31-40 years) for the negative includes (35 cases 13.7%) while (41-50 years and (61-70 years) for positive include (11cases 4.3%). Discussion: This study confirmed previous reports that the QFT test had greater sensitivity for detecting active TB than the 100-year-old TST. Conclusion: It was concluded that the quantiferon TB-2G test is a more useful diagnostic method for tuberculosis infection. QFT-Plus assay showed good sensitivity for active TB and was particularly useful for the evaluation of children with suspected LTBI, giving a low rate of indeterminate results in this group. More studies are needed to properly evaluate QFT-Plus ability in discriminating active disease from latent infection.

Biologic therapies committee. What does it provide?

ObjectiveTo assess the general healthcare impact of a Biological Therapies Commitee (immune-mediated inflammatory diseases) through prescription habits, pre-biological studies and immunization. MethodA quasi-experimental study was conducted on all naive patients of legal age who started treatment with a biological agent for an immune-mediated inflammatory disease the year before and the year after the creation of the Biological Therapies Committee. ResultsA total of 31 patients treated in 2016 and 40 patients treated in 2018 were included. Prescriptions of tumor necrosis factor alpha inhibitor drugs decreased in 2018 (from 80.6% to 45.0%, p < 0.05), while prescriptions of interleukin 12/23 inhibitors increased (from 12.9% to 35.0%, p < 0.05). Tuberculosis screening was statistically different between the two periods: the number of interferon gamma release assays performed was higher in 2018 (from 9.7% to 80.0%, p < 0.01) and the proportion of patients who successfully underwent chemoprophylaxis was higher in 2018 (from 36.4% to 81.8%, p < 0.05). The proportion of tests requested for the study of viral pathologies and the number of vaccines administered were also higher in 2018. ConclusionsThe development of a specific Biological Therapies Committee allows healthcare improvements, contributing to a deeper understanding of the medications and to preventing the infection-related adverse events. It would therefore seem advisable to develop specialized committees akin to the Biological Therapies Committee in other domains.

Integrating SARS-CoV-2-specific interferon-γ release assay testing in the evaluation of patients hospitalized with COVID-19.

T cell-mediated immunity is crucial for protection against severe COVID-19. The performance of SARS-CoV-2-specific IFN-γ release assays (IGRAs) to measure T cell responses during severe acute infection is unknown. We conducted a prospective, longitudinal analysis of patients hospitalized for confirmed COVID-19. A standardized SARS-CoV-2-specific quantitative IGRA was measured on admission. Follow-up lasted 90 days. Two hundred forty-eight patients were included; 181 (73%) were vaccinated, 142 (57.3%) were infected with the Omicron variant, and 106 (42.7%) were infected with the Delta variant. The SARS-CoV-2-IGRA result was positive (>200 mIU/mL) in 125 (50.5%) patients, with 44 (35.2%) showing concomitant mitogen-induced IFN-γ response. Compared with patients with negative and borderline results, those with positive SARS-CoV-2 IGRA were younger and showed lower frequency of co-existing comorbidities, lower median Charlson comorbidity index, lower frequency of World Health Organization (WHO) severity score > 4, higher peripheral arterial oxygen saturation to inspired fraction of oxygen (SpO2/FiO2) ratio on admission, higher S-IgG and N-IgG antibody responses, and lower mortality at 28/60/90 days. These findings were consistent for both the Omicron and Delta variants. Similar patterns to those described above were observed in the subset of patients with positive SARS-CoV-2-IGRA and indeterminate mitogen-induced responses, as well as in those exhibiting both positive SARS-CoV-2-specific and mitogen responses. Twenty-eight (11.3%) patients had borderline (100-200 mIU/mL) SARS-CoV-2-IGRA results and shared several similarities with patients with negative SARS-CoV-2 IGRA. In an adjusted Cox model, a negative SARS-CoV-2-IGRA result was found to be an independent predictor of mortality. Using a receiver operating characteristics curve analysis, we found that an IFN-γ value of 150 mIU/mL was identified as the optimal cut-off point for predicting mortality, with 79% [95% confidence interval (CI) 61-93] sensitivity, 61% (95% CI 55-68) specificity, 18% (95% CI 15-22) positive predictive value, 96% (95% CI 93-98) negative predictive value, and an area under the curve (AUC) of 70%. The assay's performance remained consistent regardless of mitogen results or the presence of the Delta or Omicron variants. IMPORTANCE The cellular immune response is essential in the protection against severe disease in patients with established SARS-CoV-2 infection. The novelty of this study lies in the evaluation of the overall performance of a standardized assay to measure cellular immune response, the SARS-CoV-2-specific interferon-γ release assay (IGRA), in hospitalized patients with severe COVID-19. The SARS-CoV-2 IGRA was shown to accurately classify patients based on disease severity and prognosis, and the study revealed that test performance was not affected by the SARS-CoV-2 variant or control tube results. We identified an assay cut-off point with a high negative predictive value against mortality. The SARS-CoV-2 IGRA in patients hospitalized for COVID-19 may be a useful tool to assess cellular immunity and adopt targeted therapeutic and preventive measures.

Building a model for the differential diagnosis of non-tuberculous mycobacterial lung disease and pulmonary tuberculosis: A case-control study based on immunological and radiological features

BackgroundAlthough the incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) is increasing annually, it is easily misdiagnosed as pulmonary tuberculosis (PTB). This study aimed to screen and identify the immunological and radiological characteristics that differentiate NTM-PD from PTB and to construct a discriminatory diagnostic model for NTM-PD, providing new tools for its differential diagnosis. MethodsHospitalised patients diagnosed with NTM-PD or PTB between January 2019 and June 2023 were included in the study. Immunological and radiological characteristics were compared between the two groups. Based on the selected differential features, a logistic regression algorithm was used to construct a discriminatory diagnostic model for NTM-PD, and its diagnostic performance was preliminarily analysed. ResultsPatients with NTM-PD were significantly older than those with PTB and the tuberculosis-specific interferon-gamma release assay (TB-IGRA) positivity rate was significantly lower in the NTM-PD group. Moreover, the absolute counts of total T lymphocytes, CD4+ T lymphocytes, CD8+ T lymphocytes, NK cells, and B lymphocytes were significantly lower in patients with NTM-PD and PTB than in healthy controls. Additionally, patients with NTM-PD had a significantly lower absolute count of B lymphocytes than the PTB group. Radiological analysis revealed significant differences between patients with NTM-PD and PTB in terms of cavity wall thickness, bronchial dilation, lung consolidation, pulmonary nodule size, pulmonary emphysema, lung bullae, lymph node calcification, pleural effusion, mediastinal and hilar lymphadenopathy, and the tree-in-bud sign. Bronchial dilation was identified as the predominant risk factor of NTM-PD, whereas TB-IGRA positivity, lymph node calcification, pleural effusion, and mediastinal and hilar lymphadenopathies were protective factors. Based on this, we constructed a discriminatory diagnostic model for NTM-PD. Its receiver operating characteristic curve demonstrated good diagnostic performance, with an area under the curve of 0.938. At the maximum Youden index of 0.746, the sensitivity and specificity were 0.835 and 0.911, respectively. ConclusionsPatients with NTM-PD and PTB exhibited impaired humoral and cellular immune functions as well as significant differences in radiological features. The constructed NTM-PD diagnostic model demonstrated good diagnostic performance. This study provides a new tool for the differential diagnosis of NTM-PD.

Cellular immune response to SARS-CoV-2 in patients with primary antibody deficiencies.

Primary antibody deficiencies (PAD) are inborn defects of the immune system that result in increased susceptibility to infections. Despite the reduced response to vaccination, PAD patients still benefit from it by reducing the risk of severe infections and complications. SARS-CoV-2 vaccines are recommended in PAD patients, but their immune effects are poorly studied. Here, we analyze virus-specific T-cell responses in PAD patients after booster vaccination against SARS-CoV-2. The study included 57 adult PAD patients on long-term immunoglobulin replacement therapy (IgRT) diagnosed with X-linked agammaglobulinemia (XLA; n = 4), common variable immunodeficiency (CVID; n = 33), isotype defects or IgG subclass deficiency (n = 6), and unclassified IgG deficiency (n = 14). Of those, 49 patients (86%) received vaccination against SARS-CoV-2 using mRNA vaccine (Pfizer-BioNTech). T-cell responses were assessed at a median of 21 (13 - 30) weeks after the booster dose (mainly the third dose) using commercially available interferon-gamma release assay (IGRA) with recombinant SARS-CoV-2 spike S1 protein. Vaccinated PAD patients showed an increased (3.8-fold, p = 0.004) release of IFN-γ upon S1 stimulation. In this group, we also documented higher serum levels of anti-SARS-CoV-2 IgG (4.1-fold, p = 0.01), although they were not associated with IGRA results. Further subgroup analysis revealed very similar IGRA responses in CVID and unclassified IgG deficiencies that were 2.4-fold increased compared to XLA and 5.4-fold increased compared to patients with isotype defects or IgG subclass deficiencies (e.g., vs. CVID: p = 0.016). As expected, CVID and XLA patients showed decreased serum titers of anti-SARS-CoV-2 antibodies compared to other studied groups (e.g., CVID vs. unclassified IgG deficiency: 4.4-fold, p = 0.006). The results did not depend directly on IgRT mode or dose, number of vaccine doses and time from the last booster dose, and clinical manifestations of PAD. Interestingly, anti-SARS-CoV-2 titers were positively correlated with serum immunoglobulin levels before IgRT (e.g., for IgA: r = 0.45, p<0.001; for IgG: r = 0.34, p = 0.009) and the percentage of peripheral blood NK cells (r = 0.48, p<0.001). Our results documented satisfactory in vitro cellular immune response in PAD patients after booster SARS-CoV-2 vaccination. Therefore, even patients with agammaglobulinemia should benefit from vaccination due to the apparent induction of cell-mediated immunity, which, together with IgRT, grants comprehensive protection against the pathogen.

Cytometry profiling of ex vivo recall responses to Coxiella burnetii in previously naturally exposed individuals reveals long-term changes in both adaptive and innate immune cellular compartments.

Q fever, caused by the intracellular bacterium Coxiella burnetii, is considered an occupational and biodefense hazard and can result in debilitating long-term complications. While natural infection and vaccination induce humoral and cellular immune responses, the exact nature of cellular immune responses to C. burnetii is incompletely understood. The current study seeks to investigate more deeply the nature of long-term cellular recall responses in naturally exposed individuals by both cytokine release assessment and cytometry profiling. Individuals exposed during the 2007-2010 Dutch Q fever outbreak were grouped in 2015, based on a C. burnetii-specific IFNγ release assay (IGRA), serological status, and self-reported clinical symptoms during initial infection, into asymptomatic IGRA-negative/seronegative controls, and three IGRA-positive groups (seronegative/asymptomatic; seropositive/asymptomatic and seropositive/symptomatic). Recall responses following in vitro re-stimulation with heat-inactivated C. burnetii in whole blood, were assessed in 2016/2017 by cytokine release assays (n=55) and flow cytometry (n=36), and in blood mononuclear cells by mass cytometry (n=36). Cytokine release analysis showed significantly elevated IL-2 responses in all seropositive individuals and elevated IL-1β responses in those recovered from symptomatic infection. Comparative flow cytometry analysis revealed significantly increased IFNγ, TNFα and IL-2 recall responses by CD4 T cells and higher IL-6 production by monocytes from symptomatic, IGRA-positive/seropositive individuals compared to controls. Mass cytometry profiling and unsupervised clustering analysis confirmed recall responses in seropositive individuals by two activated CD4 T cell subsets, one characterized by a strong Th1 cytokine profile (IFNγ+IL-2+TNFα+), and identified C. burnetii-specific activation of CD8 T cells in all IGRA-positive groups. Remarkably, increased C. burnetii-specific responses in IGRA-positive individuals were also observed in three innate cell subpopulations: one characterized by an IFNγ+IL-2+TNFα+ Th1 cytokine profile and lack of canonical marker expression, and two IL-1β-, IL-6- and IL-8-producing CD14+ monocyte subsets that could be the drivers of elevated secretion of innate cytokines in pre-exposed individuals. These data highlight that there are long-term increased responses to C. burnetii in both adaptive and innate cellular compartments, the latter being indicative of trained immunity. These findings warrant future studies into the protective role of these innate responses and may inform future Q fever vaccine design.

Serological analysis reveals differential antibody responses between TB patients and latently infected individuals from the TB endemic country of Mozambique.

Serological antibody profiling of tuberculosis (TB) patients and household contacts with latent TB infection (LTBI) could identify risk indicators of disease progression, and potentially also serve as an easily accessible diagnostic tool to discriminate between these two stages of Mycobacterium tuberculosis (Mtb) infection. Yet, despite significant efforts over many decades, neither application has yet fully materialised, and this is at least in part due to inconsistent and varying antibody profiles from different TB endemic regions. In this study, we conducted a retrospective exploratory analysis of serum antibodies in a cohort of active TB patients (ATB) and their interferon-gamma release assay (IGRA) positive household contacts (LTBI), as well as healthy controls (HC) from Mozambique, a country with a high TB burden from the Sub-Saharan region. Using several Mtb antigens as well as crude preparations of culture filtrate proteins (CFP) from Mtb and Bacille Calmette Guérin (BCG), we report that the most discriminatory response for TB and LTBI was observed for serum IgA antibodies to the MPT64 antigen, followed by IgG antibodies to Ag85B and CFP, with ATB patients having significantly higher levels than LTBI or BCG-vaccinated healthy controls. Conversely, sera from LTBI individuals had higher levels of IgG antibodies to the HBHA antigen than ATB. While our sample size (n = 21 for ATB, 18 for LTBI and 17 for HC) was too small to fully evaluate the diagnostic potential of these differing serological profiles, our study however preliminarily indicated high level of sensitivity (95%) and specificity (97%) of an ELISA MPT64-IgA test for discriminating TB from LTBI and healthy controls, supporting the notion that it alone, or possibly in combination with other antigens such as Ag85B or CFP could lead to development of an easily accessible diagnostic tool for TB.

Specific and non-specific effects of Mycobacterium bovis BCG vaccination in dairy calves.

Bovine tuberculosis (bTB) is a chronic disease mainly caused by Mycobacterium bovis, a zoonotic pathogen with economic significance as it leads to reduced milk and meat production, and high costs for control measures. The Bacillus Calmette-Guérin (BCG) vaccine, primarily used to prevent tuberculosis in humans, has also been studied for controlling bTB. While showing effectiveness in preventing M. bovis infection and disease in cattle, the BCG vaccine can induce non-specific effects on the immune system, enhancing responses to infections caused by unrelated pathogens, and also having non-specific effects on lactation. The aim of this study is to describe both the specific and non-specific effects of BCG vaccination in calves from a commercial dairy herd in central Chile. Diagnosis of M. bovis infection was performed through the IFNγ release assay (IGRA) using ESAT6/CFP-10 and Rv3615c antigens. The records of milk production, somatic cell count (SCC), clinical mastitis (CM) and retained placenta (RP) during the first lactation were compared between vaccinated and non-vaccinated animals. The breed (Holstein Friesian [HF] v/s HF × Swedish Red crossbred [HFSR]) and the season (warm v/s cold) were also analyzed as categorical explanatory variables. Results of IGRA showed significant differences between vaccinated and control groups, indicating a vaccine efficacy of 58.5% at 18 months post vaccination in HFSR crossbred animals. Although milk production did not vary, SCC and CM showed differences between groups, associated to the breed and the season, respectively. When analyzing CM and RP as a whole entity of disease, BCG showed protection in all but the cold season variables. Overall, the BCG vaccine induced protective specific and non-specific effects on health parameters, which may be influenced by the breed of animals and the season. These results provide new features of BCG protection, supporting initiatives for its implementation as a complementary tool in bTB control.

Differential levels of anti-Mycobacterium tuberculosis-specific IgAs in saliva of household contacts with latent tuberculosis infection.

Mucosal immunity is strongly elicited in early stages of many respiratory and enteric infections; however, its role in tuberculosis pathogenesis has been scarcely explored. We aimed to investigate Mycobacterium tuberculosis (Mtb) specific IgA levels in saliva in different stages of latent Tuberculosis Infection (TBI). A multiplex bead-based Luminex immunoassay was developed to detect specific IgA against 12 highly immunogenic Mtb antigens. A prospective cohort of household contacts (>14 years) of pulmonary TB cases was established in Santiago, Chile. Contacts were classified as Mtb-infected or not depending on serial interferon-γ release assay results. Saliva samples were collected and tested at baseline and at a 12-week follow-up. Mtb-specific IgA was detectable at all visits in all participants (n = 168), including the "non-Mtb infected" (n = 64). Significantly higher median levels of IgA were found in the "Mtb infected" compared to the uninfected for anti-lipoarabinomannan (LAM) (110 vs. 84.8 arbitrary units (AU), p < 0.001), anti-PstS1 (117 vs. 83 AU, p < 0.001), anti-Cell Membrane Fraction (CMF) (140 vs. 103 AU, p < 0.001) and anti-Culture Filtrate Proteins (CFP) (median 125 vs. 96 AU, p < 0.001), respectively. Nonetheless, the discriminatory performance of these specific mucosal IgA for TBI diagnosis was low. Saliva holds Mtb-specific IgA against several antigens with increased levels for anti-LAM, anti-PstS1, anti-CMF and anti-CFP found in household contacts with an established TBI. The role of these mucosal antibodies in TB pathogenesis, and their kinetics in different stages of Mtb infection merits further exploring.

Low performance of interferon gamma release assay Quantiferon-TB gold coupled or not with Pst1/3/lipoglycan humoral detection to predict Mycobacterium tuberculosis complex disease in a low-burden area

Whole T cell interferon gamma release assays such as QuantiFERON-TB Gold Plus (QTF-TB) are used to evaluate Mycobacterium tuberculosis complex (MTC) exposure but fail to discriminate latent tuberculosis infection (LTBI) from active disease. In this study conducted in a low-burden area, 1215 patients presenting MTC risk and tested both for QTF-TB and mycobacterial infection (microscopy, culture, and/or PCR) were selected, as well as 1298 controls screened with QTF-TB before medical recruitment. The humoral response (LIODetect®TB-ST) was further evaluated in 199 selected patients. In patients with active disease, MTC positivity (culture and/or PCR with species identification) was associated with QTF-TB positivity (45/56, 80.4 %). Although QTF-TB1/TB2 peptides were not suitable for discriminating against active MTC disease from LTBI, the cut-off value of 4.4 IFN-γ IU/mL produced the best diagnostic performance for MTC detection. Lower levels of QTF-TB were reported among patients with isolated active pulmonary MTC as compared to a lymph-nodal location and a disseminated form. Next, antibodies were detected in 4/55 (7.3 %) active MTC disease cases, while negative in cases of LTBI and indeterminate/negative QTF-TB. In conclusion, the added value to combine cellular (QTF-TB) and humoral (LIODetect®TB-ST) assays to predict an active MTC disease is limited.

Advances in Diagnostics and Drug Discovery against Resistant and Latent Tuberculosis Infection.

Latent tuberculosis infection (LTBI) represents a subclinical, asymptomatic mycobacterial state affecting approximately 25% of the global population. The substantial prevalence of LTBI, combined with the risk of progressing to active tuberculosis, underscores its central role in the increasing incidence of tuberculosis (TB). Accurate identification and timely treatment are vital to contain and reduce the spread of the disease, forming a critical component of the global strategy known as "End TB." This review aims to examine and highlight the most recent scientific evidence related to new diagnostic approaches and emerging therapeutic treatments for LTBI. While prevalent diagnostic methods include the tuberculin skin test (TST) and interferon gamma release assay (IGRA), WHO's approval of two specific IGRAs for Mycobacterium tuberculosis (MTB) marked a significant advancement. However, the need for a specific test with global application viability has propelled research into diagnostic tests based on molecular diagnostics, pulmonary immunity, epigenetics, metabolomics, and a current focus on next-generation MTB antigen-based skin test (TBST). It is within these emerging methods that the potential for accurate distinction between LTBI and active TB has been demonstrated. Therapeutically, in addition to traditional first-line therapies, anti-LTBI drugs, anti-resistant TB drugs, and innovative candidates in preclinical and clinical stages are being explored. Although the advancements are promising, it is crucial to recognize that further research and clinical evidence are needed to solidify the effectiveness and safety of these new approaches, in addition to ensuring access to new drugs and diagnostic methods across all health centers. The fight against TB is evolving with the development of more precise diagnostic tools that differentiate the various stages of the infection and with more effective and targeted treatments. Once consolidated, current advancements have the potential to transform the prevention and treatment landscape of TB, reinforcing the global mission to eradicate this disease.

Differential effects of selective versus unselective sphingosine 1-phosphate receptor modulators on T- and B-cell response to SARS-CoV-2 vaccination

Background: Sphingosine 1-phosphat receptor modulators (S1PRMs) have been linked to attenuated immune response to SARS-CoV-2 vaccines. Objective: To characterize differences in the immune response to SARS-CoV-2 vaccines in patients on selective versus unselective S1PRMs. Methods: Monocentric, longitudinal study on people with multiple sclerosis (pwMS) on fingolimod (FTY), siponimod (SIP), ozanimod (OZA), or without disease-modifying therapy (DMT) following primary and booster SARS-CoV-2 vaccination. Anti-SARS-CoV-2 antibodies and T-cell response was measured with electro-chemiluminescent immunoassay and interferon-γ release assay. Results: Primary vaccination induced a significant antibody response in pwMS without DMT while S1PRM patients exhibited reduced antibody titers. The lowest antibodies were found in patients on FTY, whereas patients on OZA and SIP presented significantly higher levels. Booster vaccinations induced increased antibody levels in untreated patients and comparable titers in patients on OZA and SIP, but no increase in FTY-treated patients. While untreated pwMS developed a T-cell response, patients on S1PRMs presented a diminished/absent response. Patients undergoing SARS-CoV-2 vaccination before onset of S1PRMs presented a preserved, although attenuated humoral response, while T-cellular response was blunted. Conclusion: Our data confirm differential effects of selective versus unselective S1PRMs on T- and B-cell response to SARS-CoV-2 vaccination and suggest association with S1PRM selectivity rather than lymphocyte redistribution.

Using Electronic Health Record Data to Measure the Latent Tuberculosis Infection Care Cascade in Safety-Net Primary Care Clinics

Prevention of tuberculosis disease through diagnosis and treatment of latent tuberculosis infection is critical for achieving tuberculosis elimination in the U.S. Diagnosis and treatment of latent tuberculosis infection in safety-net primary care settings that serve patients at risk for tuberculosis may increase uptake of this prevention effort and accelerate progress toward elimination. Optimizing tuberculosis prevention in these settings requires measuring the latent tuberculosis infection care cascade (testing, diagnosis, and treatment) and identifying gaps to develop solutions to overcome barriers. We used electronic health record data to describe the latent tuberculosis infection care cascade and identify gaps among a network of safety-net primary care clinics. Electronic health record data for patients seen in the OCHIN Clinical Network, the largest network of safety-net clinics in the U.S., between 2012 and 2019 were extracted. electronic health record data were used to measure the latent tuberculosis infection care cascade: patients who met tuberculosis screening criteria on the basis of current recommendations were tested for tuberculosis infection, diagnosed with latent tuberculosis infection, and prescribed treatment for latent tuberculosis infection. Outcomes were stratified by diagnostic test and treatment regimen. Among 1.9 million patients in the analytic cohort, 43.5% met tuberculosis screening criteria, but only 21.4% were tested for latent tuberculosis infection; less than half (40.4%) were tested using an interferon-gamma release assay. Among those with a valid result, 10.5% were diagnosed with latent tuberculosis infection, 29.1% of those were prescribed latent tuberculosis infection treatment, and only 33.6% were prescribed a recommended rifamycin-based regimen. Electronic health record data can be used to measure the latent tuberculosis infection care cascade. A large proportion of patients in this safety-net clinical network are at high risk for tuberculosis infection. Addressing identified gaps in latent tuberculosis infection testing and treatment may have a direct impact on improving tuberculosis prevention in primary care clinics and accelerate progress toward elimination.

B-108 T-cell-mediated Immunity against SARS-CoV-2 in Health Care Workers: Head-to-head Comparison of Two Interferon-Gamma Release Assays and Associations between Cellular and Humoral Immunity

Abstract Background T-cell responses are a crucial constituent in the adaptive immunity to SARS-CoV-2 and can be quantified using interferon-gamma (IFN-γ) release assays (IGRAs). This study aimed at comparing the results of two commercial IGRA systems, the EUROIMMUN Quan-T-Cell SARS-CoV-2 and the Oxford Immunotec T-SPOT.COVID, presenting the first head-to-head comparison of these two assays for the evaluation of SARS-CoV-2-specific T-cell activity. Methods Blood samples were collected at the Public Health Institute Ostrava from 90 health care professionals with a history of COVID-19 infection or vaccination. All samples were tested for T-cell-mediated immunity using the two IGRAs as well as for humoral immunity using the EUROIMMUN Anti-SARS-CoV-2 QuantiVac ELISA IgG and an in-house virus neutralization test. Results Similar results were obtained by both IGRAs, yet the sensitivity of the Quan-T-Cell appeared to be insignificantly higher than that of the T-SPOT.COVID. Conclusion Both assays demonstrated excellent overall agreement with virus neutralization activity and anti-S IgG positivity, with the only exception that 4/6 subjects in the subgroup of unvaccinated Omicron convalescents were devoid of IgG. In these cases, however, T-cell responses were at least borderline positive, indicating that IGRAs provide higher sensitivity in detecting immune responses to SARS-CoV-2 than do IgG-specific assays. This applies particularly to unvaccinated persons who contracted only SARS-CoV-2 Omicron variant infection but is also likely to be relevant to other patient groups.

A-285 Performance Evaluation of LIAISON® QuantiFERON®-TB Gold Plus Assay and Its Use in Long-Term Care Facilities

Abstract Background Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis with 7860 cases reported in 2021 in the United State and estimated 13 million people are living with Latent TB infection (LTBI); Early detection of TB infection is crucial to prevent the spread of the disease; there are two types of tests for TB and LTBI: Tuberculin Skin Test (TST) and Interferon-Gamma Release Assay (IGRA). Although TST has good sensitivity but false-negative reactions occur in certain population and the specificity of is decreased among persons with prior Bacillus Calmette-Guérin (BCG) vaccination, especially those vaccinated post-infancy and those with repeat vaccination. Similarly, persons living in areas where nontuberculous mycobacteria are common are at increased risk of having false-positive TST reactions. IGRA is blood-based laboratory test that measures responses to TB-specific peptide antigens in whole blood. Like the tuberculin skin test (TST), it is an indirect test for M. tuberculosis infection, but is more specific than TST and is unaffected by prior BCG vaccination and most environmental mycobacterial infections. Methods The LIAISON® QuantiFERON®-TB Gold Plus assay is an in vitro diagnostic test for the detection of interferon-γ (IFN-γ) in human lithium heparin plasma by chemiluminescence immunoassay (CLIA) using the LIAISON ® XL Analyzer. The clinical specificity and sensitivity were 96.9% and 84.4% respectively. Clinical studies have shown Positive Percent Agreement (PPA) of 97.4% and Negative Percent Agreement (NPA) of 98.6%. We evaluated the precision, reproducibility, and correlated patient results to our reference lab results. 452 samples collected from Long-Term Care facilities resident were run over 9 months. Statistical analyses were done using Analyse-it. Results The percentage agreement for precision, reproducibility, and accuracy were 100%. The correlation with the reference laboratory was 100% agreement. We found 14.8% of samples tested were positive, 83.2% were negative and 2.0% were indeterminate. Conclusion The LIAISON® QuantiFERON®-TB Gold Plus assay offers the benefit of a fully automated with high sensitivity and specificity. The faster turnaround will aid the physician in the diagnosing M. tuberculosis, eliminates the need for two-step testing, and is preferred in patients who received BCG vaccination. In addition, with the growing geriatric population, the availability of this test will give the physician the opportunity to follow the 2016 American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA)/CDC clinical practice guidelines for using IGRAs in older patients.