Abbott HCV core Ag and HCV RNA Comparison Study Nazibrola Chitadze1, R. Sukhiashvili1, M. Zarandia1, G. Chanturia1, M. Alkhazashvili1, J. Drobeniuc2, G. Gloherty3, E. Adeishvili1 National Center for Disease Control & Public Health, Tbilisi, Georgia1; Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, GA, USA2; Abbott Diagnostics, Abbott Park, IL, USA 3 Introduction Hepatitis C virus (HCV) infection is endemic in many countries of the world, including Georgia. The population‑based cross-sectional household serosurvey has been undertaken by the National Center for Disease Control and Public Health (NCDC) of Georgia to determine the prevalence of hepatitis C (HCV) and B virus (HBV) infection in the country in 2015. These data are used to define the burden of HCV/HBV and risk factors for transmission for successful completion of HCV elimination program launched by the Government of Georgia with support of main US partner - CDC. Georgian Government plans to eliminate Hepatitis C by 2020. Accurate testing strategies are required to confirm current infection for effective screening, disease control and prevention strategy. Company Abbott Diagnostics expressed the willingness to participate in HCV elimination program by initiating research – testing anti-HCV positive samples using recently designed HCV core antigen tests and compare results with HCV RNA tests obtained during several studies. This study would help to validate effectiveness of HCV core Ag test in low income country with high prevalence of hepatitis C. The overall study would be split on two parts: Study 1. Evaluate new algorithm for screening and confirmation that will include Abbott Architect HCVcore Ag test; Study 2: The Evaluate/validate utility of Abbott Architect HCV core antigen test in monitoring HCV positive patients on DAA therapy. The study was conducted at Serology and Molecular Epidemiology laboratories of NCDC-Lugar Center Abbott provided research instruments - ARCHITECT i2000 Immunoassay Analyzer and m2000 RealTime System and all necessary materials for performing testing. Results Overall discordance between both methods was 2.5%. Of the 24 RNA +ve / cAg –ve samples 16 had viral loads <1,500IU/ml (of these 6 were <30 IU/mL), 2 had a viral load >4,000 IU/mL and 6 were RNA qualitatively positive (no viral load available). Of the 10 samples which gave a cAg GZ result 3 were HCV RNA –ve and 7 were from HCV RNA +ve samples. Of the 7 HCV RNA +ve samples 4 were from samples with viral load <1,000 IU/mL while 2 had a viral load of approximately 30,000 IU/mL and 1 was RNA qualitatively positive. The two samples which were cAg +ve / RNA –ve were low reactive <15 fmol/L.   (presented in Figure 2, below). Figure 2: Abbott HCV core Ag vs HCV RNA Testing HCV core Ag HCV RNA Negative Positive Total Nonreactive 320 98.5% 24*** 2.5% 344 GZ-Reactive 3 0.9% 7** 0.7% 10 Reactive 2* 0.6% 938 96.8% 940 325 969 1294 Methods A total of 4,235 samples obtained from Blood Banks, Harm Reduction Networks (HRN), Provider Clinics, Screening centers and A cross-sectional, nationally representative seroprevalence survey of individuals aged ≥18 years, conducted in Georgia from May-August 2015 (NSS), were tested with the ARCHITECT HCV core antigen assay (presented in Figure 1, below) Many of the obtained samples were of poor quality (lipeamic/fibrin/low volume). Due to limited sample volume repeat testing of GZ samples was performed but not in duplicate Study algorithm could not be followed due to administrative, paperwork and technical issues Samples for HCV core Ag were tested using ARCHITECT i2000 Immunoassay Analyzer NAT testing were conducted using ARCHITECT m2000 RealTime System. Specimens with cAg concentration <3 fmol/L are considered nonreactive, those >3 fmol/L are considered reactive but those >3 but <10 fmol/L are considered “greyzone” (GZ) and should be re-tested in duplicate. Samples obtained from HRN and NSS, 963 and 331 respectively, had available HCV RNA results for comparison. * HCVcoreAg Low reactive <15 fmol/L ** 2 samples ~30,000 IU/ML; 4 - <1,000 IU/ML; 1 - qualitative from seroprevalence; *** 6 samples - <30 IU/ML; 6 - <500 IU/ML; 2 - <1000 IU/ML; 2 - <1,500 IU/ML; 2 - >4,000 IU/ML; 6 - qualitative from seroprevalence; Summary   Study for evaluation of Abbott HCV core Ag test was conducted at NCDC Lugar Center. Under the Study project i2000 and m2000 instruments were provide by Abbott diagnostics. Study algorithm could not be followed due to administrative, paperwork and technical issues. Main discrepancy between HCVcoreAg and RNA tests was 2.5%. Study results will serve for HCV elimination program in the country. Figure 1: Total Samples Tested on Abbott HCV core Ag Samples by Organizations: HCVcoreAg Nonreactive GZ-Reactive Reactive Grand Total Blood Banks (anti-HCV + and -) 1190 20 613 1823 Harm Reduction Network (anti-HCV +) 279 9 772 1060 Provider Clinic 107 14 674 795 Screening 102 4 120 226 Seroprevalence 2015 97 1 233 331 Grand Total 1775 48 2412 4235 Acknowledgements Abbott Diagnostics - for providing instruments, reagents, supplies and technical support Centers for Disease Control and Prevention (CDC) - for technical support in planning and implementation of the study Ministry of Labour, Health and Social Affairs of Georgia - for support the study Clinics and Blood Banks - for collecting and providing plasma samples NCDC regional and Lugar Center laboratory teams