Comparison of two mycobacterial strains in performance of the whole blood mycobacterial growth inhibition assay in Indian children. (December 2022)

• Record Type: Journal Article
• Authors: Venkataraman, Aishwarya; Shanmugam, Sivakumar; Balaji, Sarath; Mani, Karthick; Shanmugavel, Ashok Kumar; Muthuramalingam, Kannan; Hissar, Syed; Thiruvengadam, Kannan; Selladurai, Elilarasi; Smuk, Melanie; Hanna, Luke Elizabeth; Prendergast, Andrew J.
• Is Part Of: Tuberculosis. Volume 137(2022)
• Publication Date: 2022-12
• Subjects: MGIA -- Tuberculosis -- In vitro assay -- Mycobacterial growth inhibition assay; 616.995
• DOI: 10.1016/j.tube.2022.102255
• Languages: English
• ISSNs: 1472-9792

Abstract

Abstract: A major challenge in tuberculosis is identifying correlates of a protective immune response. The Mycobacterial Growth Inhibition Assay (MGIA) is a functional assay providing an integrated measure of the host immune response to mycobacteria. However, its feasibility is limited by reliance on biosafety level 3 facilities, and its performance has not been widely evaluated in TB-endemic settings. Here, we compared two mycobacterial strains ( M. tuberculosis H37Rv versus attenuated M. bovis BCG) in the performance of whole-blood MGIA in 30 TB-exposed children (median age 2 years) in Chennai, India. The time-to-positivity in both assays was similar (5.7 days vs 6 days) and the mycobacterial growth of M. tuberculosis H37Rv and M. bovis BCG were correlated (r = 0.64, p < 0.0001). In Bland-Altman analysis, the bias was −0.54 days (95% limit of agreement −2.08, 0.99). Collectively, our results indicate that M. tuberculosis H37Rv can be substituted with the less virulent M. bovis BCG strain to improve feasibility of the MGIA assay, particularly in low-income settings.