Automated RIBA (TM) HCV strip immunoblot assay: A novel tool for the diagnosis of hepatitis C virus infection in hemodialysis patients

Hemodialysis (HD) patients remain a high-risk group for hepatitis C virus ( HCV) infection. Serological assays (enzyme-linked immunosorbent assays, ELI SAs) are the only tests currently approved by the Food and Drug Administrat ion in the United States for the diagnosis of HCV. The RIBA (TM) HCV Strip Immunoblot Assay (SIA) is an established method for supplemental testing of repeat reactive hepatitis C ELISA patients on HD. However, the current man ual procedure is labor intensive, requiring subjective band scoring and res ult interpretation. Recently, the automated CHlRON (R) RIBA (TM) HCV Proces sor System has been designed to perform RIBA supplemental testing. The CHIR ON RIBA HCV Processor System consists of a bench-top instrument that provid es objective evaluation of the RIBA immunoblot strips, by measuring the lig ht differentially reflected from the developed bands and white background, creating a density of reflectance. The CHIRON RIBA HCV Processor System ass esses the intensity of each of the reactive bands in relation to the intens ity of the internal control bands on each RIBA HCV strip. Comparison betwee n processor and manual protocols was performed using a large (n = 200) coho rt of ELISA 3.0 HCV negative and positive patients on maintenance HD. The t est characteristics of RIBA HCV 3.0 SIA were identical with manual and auto mated runs. The relative intensity values of antigenic bands by the CHIRON RIBA HCV 3.0 Processor System between anti-HCV positive and negative patien ts were significantly different; only 15 of 784 (1.9%) antigenic bands had borderline reactivities. The correlation of rest results between manual and automated runs was very high (kappa value 0.989). Among positive results b y RIBA HCV 3.0 SIA, there was a strong concordance between manual and autom ated runs with regard to the pattern of reactivity (kappa value 0.943). The discordant results between manual and automated protocols were attributabl e to increased variability of antigen scores close to the cutoff value for both tests. In conclusion, the CHIRON RIBA HCV 3.0 Processor System is capa ble of performing RIBA HCV 3.0 SIA in the HD population accurately with min imal operator involvement. The test characteristics of RIBA HCV 3.0 SIA wer e identical by manual and automated runs. There was a strong correlation be tween the results of the manual and automated runs; the few discordant resu lts between the two procedures were mostly due to increased variability of antigen scores close to the cutoff value for both tests. The Centers for Di sease Control and Prevention in the USA have recently included chronic HD p atients among those persons for whom routine HCV testing is recommended; HC V-infected patients on HD often have a high rate of indeterminate results b y manual RIBA technology which is operator dependent for band scoring and r esult interpretation. The CHIRON RIBA HCV 3.0 Processor System may be very useful for supplemental anti-HCV testing of ELISA repeat reactive specimens in clinical practice within dialysis units. Copyright (C) 2001 S. Karger A G, Basel.