Genotypes of Hepatitis C Virus Amplified from Sera Non-Reactive to Anti-HCV Enzyme Immunoassay

Sung, Heungsup; Oh, Heung Bum; Lee, Eun Hee

Abstract

BACKGROUND
Despite sensitive antibody-based blood-donor screening, a residual risk of transfusion-transmitted viral infections exists. For hepatitis C virus (HCV), window-period donations account for the major risk. In the previous studies, however, estimates of the risk of post-transfusion hepatitis C was much higher than that calculated from the risk of donation in the seroconversion window. Therefore, we reevaluated the rate of HCV RNA positive/ anti-HCV negative samples using the two domestic anti-HCV EIA kits. All the samples showing HCV RNA positive/ anti-HCV negative were genotyped.
METHODS
A total of 909 patients' samples showing HCV RNA positivity using the Amplicor HCV TEST (Roche Diagnostic Systems) was retested for antibody presence with the LG HCD 3.0 (LG Chemicals) and DONG-A HCV 3.0 (DONG-A Pharmaceuticals) EIA kit. Samples that were non-reactive to the EIA kits were genotyped by INNO-LiPA HCV kit (INNOGENETICS, Belgium).
RESULTS
Among 909 tested samples, 5 samples showed nonreactivity to both anti-HCV EIA kits, while 1 sample was nonreactive only to DONG-A HCV 3.0. When RT-PCR for HCV was performed using stored or follow-up samples, 4 samples showed negative results. Medical records were also reviewed and found to be false positive for HCV RT-PCR in 3 of those 4 patients. In the case of one remaining patient, the follow-up RT-PCR was negative. Finally, 2 samples (0.2%) showed HCV RNA positive/ anti-HCV negative. The 2 samples were genotyped as 1b type.
CONCLUSIONS
More than 99.8% of HCV RNA positive samples showed reactivity to anti-HCV EIA kits. There were two samples that were non-reactive to anti-HCV kits and were genotyped as 1b type, which is the most common subtype in Korea. Our study suggests that false negativity of anti-HCV in Korea would very rarely be caused by uncommon HCV genotypes.