EVALUATION OF CLINICAL USEFULNESS OF ELISPOT USING ROP-ESAT6-CFP10 ANTIGEN

Abstract

SESSION TITLE: TB or Not TB: That Is the Question: Better Ways to Diagnose Tuberculosis SESSION TYPE: Original Investigations PRESENTED ON: 10/22/2019 10:45 AM - 11:45 AM PURPOSE: Mantoux tuberculin skin test and interferon gamma release assay (IGRA) are used to diagnose latent tuberculosis (TB) infection. Although IGRA is more sensitive and specific than skin test, it is costly. Novel Mycobacterium tuberculosis specific antigen, ROP-ESAT6-CFP10, using recombinant overlapping peptide (ROP) technique was developed. ROP consists of peptides, joined into a single molecule linked by enzyme cleavage sites, and these overlapping peptides cover the target amino acid sequence. With this ROP technique, M. tuberculosis specific antigen can be produced in a short period of time with easier quality control, which are more economic to manufacture. We evaluated the performance of ELISpot using newly developed ROP-ESAT6-CFP10. METHODS: Patients who were diagnosed as pulmonary tuberculosis within one year period were enrolled in the study. Enrolled patients were “AFB culture positive” or “AFB stain positive and TB-PCR positive”. Healthy candidates without any respiratory symptoms with normal chest x-ray were also enrolled. Blood samples from the study subjects were tested with QuantiFERON-TB Gold (Qiagen, Germantown, Maryland), T-SPOT.TB (Oxford Immunotec, Oxford, UK) as manufacture’s instruction. In addition, instead of using ESAT6 and CFP10 antigen, ROP-ESAT6-CFP10 were used as TB-specific antigen with T-SPOT.TB assay. Agreement with between assays, sensitivity and specificity were evaluated. RESULTS: Ten pulmonary TB patients and seventeen healthy candidates were enrolled in the study. The kappa between ROP-ESAT6-CFP10 and T-SPOT.TB was 0.743. The kappa between ROP-ESAT6-CFP10 and QuantiFERON-TB Gold was 0.545. Sensitivity was 90%, 80%, and 60% in ROP-ESAT6-CFP10, T-SPOT.TB, and QuantiFERON-TB Gold, respectively. Specificity of these assays were 100%. CONCLUSIONS: ELISpot using newly developed ROP-ESAT6-CFP10 showed very good agreement with T-SPOT.TB and moderate agreement with QuantiFERON-TB Gold. CLINICAL IMPLICATIONS: Newly developed TB-specific antigen, ROP-ESAT6-CFP10 is easy to mass-produce and shows very good agreement with T-SPOT.TB. When ROP-ESAT6-CFP10 is applied to IGRA, assay cost can be reduced. DISCLOSURES: No relevant relationships by Chang Hyeok An, source=Web Response No relevant relationships by Eun-Hye Ha, source=Web Response No relevant relationships by Soo-Kyung Kim, source=Web Response no disclosure on file for Sang Joon Park