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

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.

Positive Rate of HCV RNA in Anti-HCV Immunoblot Indeterminate Samples from Blood Donors and Analysis of Reactivity of Enzyme Immunoassay Kits to Indeterminate Samples / 대한수혈학회지

BACKGROUND: Positive rate of HCV RNA in anti-HCV immunoblot indeterminate samples from Korean blood donors was investigated in this study. Futhermore, reactivity of enzyme immunoassay kits was evaluated according to patterns of band reactivity and RNA positivity of indeterminate samples. METHODS: HCV RNA was tested from a total of 180 samples that had been repeatedly reactive to LG HCD 3.0 or DONG-A HCV 3.0 and further confirmed to be indeterminate by LG HCD CONFIRM at 14 Korean Red Cross Blood Centers in 1997. Correlation between HCV RNA and reactivity to each recombinant antigens was analysed. Three kinds of EIA kits such as HCD 3.0, DONG-A HCV 3.0 and Cobas Core Anti-HCV EIA kits were tested of their reactivity to 56 samples that had shown single band positivity on LG HCD CONFIRM. RESLUTS: HCV RNA was detected in 11 (6.1%) of 180 samples. Positivity of 897 band showed positive correlation with HCV RNA positivity (p<0.001), while Core518 showed negative correlation (p<0.001). DONG-A HCV 3.0 showed negative reaction to two samples with anti-897 specificity and HCV RNA, while LG HCD 3.0 and Cobas Core HCV showed negative reaction to one sample with anti-EIE2NS4 and HCV RNA. CONCLUSION: Positive rate of anti-HCV immunoblot indeterminate samples from Korean blood donors was 6.1%. In case of indeterminate results by LG HCD CONFIRM, positive reaction to 897 band highly suggests the presence of HCV RNA, while Core518 the absence of HCV RNA. It is highly recommended that specificity of Core518 antigen be increased in LG HCD 3.0 or LG HCD CONFIRM and sensitivity of recombinant antigen from the 3rd non-structural region of HCV genome be increased in DONG-A HCV 3.0.