Evaluation of multi-antigen serological screening for active tuberculosis among people living with HIV

Abstract

Better triage tests for screening tuberculosis (TB) disease are needed for people living with HIV (PLHIV). We performed the first evaluation of a previously-validated 8-antigen serological panel to screen PLHIV for pulmonary TB in Kampala, Uganda. We selected a random 1:1 sample with and without TB (defined by sputum culture) from a cohort of PLHIV initiating antiretroviral therapy. We used a multiplex microbead immunoassay and an ensemble machine learning classifier to determine the area under the receiver operating characteristic curve (AUC) for Ag85A, Ag85B, Ag85C, Rv0934-P38, Rv3881, Rv3841-BfrB, Rv3873, and Rv2878c. We then assessed the performance with the addition of four TB-specific antigens ESAT-6, CFP-10, Rv1980-MPT64, and Rv2031-HSPX, and every antigen combination. Of 262 participants (median CD4 cell-count 152 cells/μL [IQR 65-279]), 138 (53%) had cultureconfirmed TB. The 8-antigen panel had an AUC of 0.53 (95% CI 0.40-0.66), and the additional 4 antigens did not improve performance (AUC 0.51, 95% CI 0.39-0.64). When sensitivity was restricted to �90% for the 8-and 12-antigen panel, specificity was 2.2% (95% CI 0-17.7%) and 8.1% (95% CI 0-23.9%), respectively. A three-antigen combination (Rv0934-P38, Ag85A, and Rv2031-HSPX) outperformed both panels, with an AUC of 0.60 (95% CI 0.48-0.73), 90% sensitivity (95% CI 78.2-96.7%) and 29.7% specificity (95% CI 15.9-47%). The multi-antigen panels did not achieve the target accuracy for a TB triage test among PLHIV. We identified a new combination that improved performance for TB screening in an HIV-positive sample compared to an existing serological panel in Uganda, and suggests an approach to identify novel antigen combinations specifically for screening TB in PLHIV.

Enhanced serodiagnostic potential of a fusion molecule consisting of Rv1793, Rv2628 and a truncated Rv2608 of Mycobacterium tuberculosis

“…The 3D structural models of all the proteins were successfully generated through RaptorX (Fig 7). All the protein models passed the validation and accuracy tests performed through WHATCHECK, Verify3D and MolProbity softwares.…”

“…In this regard, serological methods are inexpensive, prompt and easy to use. Antibodies are a popular candidate as TB biomarkers and a number of Mtb antigens have been studied for TB serodiagnosis [6,7]; the use of single antigens has however failed to achieve reproducible sensitivity and specificity concurrently [4]. Because of the overwhelming benefits of an effective antibody-based diagnostics, it is critical that all approaches are taken to identify antigen combinations that are reproducibly detected by antibodies from a wide range of individuals.…”

Tuberculosis Diagnosis: Updates and Challenges

“…Most of these biomarkers are inflammatory markers and vary widely among patients depending upon their metabolic and disease states. Even though WHO is recommending against using commercial serological assays, antibodies, and combinations of antigens in the test panel improved performance of TB screening tests [24].…”

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

“…Nevertheless, there is a renewed effort to improve on serodiagnosis of TB by either combining different tests (4), or combining multiple antigens or epitopes of Mtb (4)(5)(6)(7)(8)(9)(10)(11)(12), with some of the reports claiming discriminatory potential between active TB and LTBI (6,7,9,10). In this study, we performed an exploratory study on a historic set of serum samples from TB patients, LTBI and healthy (BCG vaccinated) controls in Mozambique, collected between 2016 and 2018 as part of a wider study [ (13,14) the EMI-TB project].…”