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.

Effectiveness of Supplemental Enzyme Immunoassay Using Abbott IMx HCV Kit for the Anti-HCV Positive Donors / 대한수혈학회지

BACKGROUND: Only 39% was the positive predictive value of anti-hepatitis C virus (HCV) antibody test done by Korean Red Cross. Supplemental enzyme immunoassay (EIA) by another EIA kit may be also effective for reporting the more correct result to donors, instead of expensive supplemental immunoblot test. METHODS: All repeatedly reactive blood samples by EIA from 16 regional blood centers were retested for anti-HCV antibody by Abbott IMx HCV kit and LG HCD CONFIRM immunoblot kit. Presence of viral RNA was also confirmed using Amplicor HCV TEST kit from 180 samples, which were proportionately selected according to supplemental EIA and Immunoblot results. RESULTS: Of 2,211 repeatedly reactive samples, 909 samples (41%) were reactive and 1,302 (59%) samples were non-reactive with IMx HCV kit. 81% of reactive samples also showed positive pattern on the LG HCD CONFIRM strips and 79% of 1,302 samples showed negative pattern. RNA positivity was estimated 66% and 17% in Abbott IMx HCV positive and negative samples respectively, and 72%, 6%, 20% in LG HCD CONFIRM positive, indeterminate and negative samples respectively. CONCLUSION: HCV RNA positivity in positive samples by Abbott IMx HCV or LG HCD CONFIRM was not statistically significant (z=0.57 < 1.96, alpha=0.05). RNA detection rate by Abbott IMx HCV or LG HCD CONFIRM among HCV RNA positive samples, which was estimated as 73%, 70% respectively, was also statistically insignificant (z=0.375 < 1.96, alpha=0.05). So, it seems to be a good and economical practice that donors are notified of anti-HCV antibody results after supplemental EIA test using Abbott IMx HCV kit.