Clinical evaluation of an HIV-1 and HCV assay and demonstration of significant reduction of the HCV detection window before seroconversion

BACKGROUND: One HIV-1 and HCV assay simultaneously detects HIV-1 and HCV RNA (Procleix, Chiron Corp.). The main intended use of the assay is the testing of blood and blood products in blood banking. STUDY DESIGN AND METHODS: To evaluate the clinical sensitivity of the assay, 164 anti-HIV-1+ and 160 anti-HCV+ patients of different viral load were tested. The assay specificity was determined in 1000 HIV-1- and HCV-seronegative blood donors. The ability of the assay to detect different HCV genotypes was investigated in a total of 40 patients of different genotypes (1-4). Furthermore, to investigate the reduction of the HCV window phase before seroconversion, serial samples of 25 hemodialysis patients who seroconverted to anti-HCV were also tested. RESULTS: The assay detected all 60 HIV-1-infected patients with a viral load of greater than 50 copies per mL and 48 of 104 patients with a viral load of less than 50 copies per mL. Moreover, all 60 patients with an HCV RNA load of greater than 521 IU per mL and 7 of 100 patients with a viral load of less than 50 IU per mL tested positive. The assay specificity was found to be 100 percent. In addition, all 40 patients of different HCV genotypes were successfully detected. Finally, the median time that the assay detected HCV infection before second- and third-generation anti-HCV assay was found to be 183 and 91 days, respectively. CONCLUSION: The assay sensitivity and specificity, its ability to detect different HCV genotypes, and the significant reduction of window period of HCV infection further support its use for improving the safety of blood and blood products.