ABSTRACT
Objective To analyze the positive results of HIV antibody screening in the laboratory of AIDS confirmation center of Hubei Provincial Center for Disease Control and Prevention from 2014 to 2020, and to provide a basis for improving detection strategies. Methods A total of 2 728 primary screening positive specimens received by the laboratory of Hubei confirmation center from 2014 to 2020 were retested with two reagents. Specimens with at least one reactive result were confirmed with western blot (WB). The samples with uncertain or negative WB results were further confirmed by nucleic acid quantitative detection. The test results were analyzed retrospectively. Results A total of 2 297 specimens with positive retest results were confirmed by WB, with a positive rate of 93.47%. The highest proportion of patients was from medical institutions. The positive rate detected by 4 diagnostic kits was apparently higher in S/CO＞10 cases than that in S/CO≤10, and the difference was statistically significant (P 5 000cps / ml, and 12 cases were TND. 13 of the 30 WB negative samples had nucleic acid test results＞5 000CPs/mL . Conclusions The coverage of HIV screening laboratories in hospitals at all levels should be further increased to find more HIV infected persons. The anti-HIV ELISA S/CO ratio is correlated with the positive results confirmed by western blot. Therefore, ELISA S/CO ratio can be used to predict anti-HIV antibody positivity. For samples with uncertain or negative WB detection, supplemental nucleic acid test should be carried out timely for early diagnosis.
ABSTRACT
BACKGROUND: Recombinant immunoblot assay (RIBA) or RNA test is considered to be a supplemental test for confirming a HCV infection. A correlation has been reported between the signal-to-cutoff (S/CO) ratios of a third generation HCV enzyme-linked immunosorbent assay (ELISA) and a confirmed HCV infection. This study examined the results of an evaluation of domestic anti-HCV EIA and immunoblot kit (RIBA) in Korean donors. METHODS: A total of 375,576 donor samples were tested for anti-HCV using the LG third generation HCV ELISA (LG HCD 3.0 TMB, LGphD, Korea) and HCV RNA by NAT (Biomerieux/Roche RT-PCR, 24 pool). The anti-HCV repeat reactive samples were further tested by third generation RIBA (LG HCD Confirm, LGphD, Korea). A positive result by either the nucleic acid amplification test (NAT) or RIBA was interpreted as a confirmed HCV infection. RESULTS: There were 506 out of the 375,576 donor samples (0.13%) that were anti-HCV repeat reactive (RR) by routine screening ELISA. The confirmed HCV prevalence in the donors was 0.01% (RIBA 42/375,570, RNA 36/375,570). 443 samples from the 506 repeat reactive samples in ELISA (87.6%) showed a S/CO ratio 3.6 (mean 4.40+/-0.80), compared with the negative group (mean 1.54+/-0.64). CONCLUSION: There was a good correlation between a high S/CO ratios and a confirmed HCV infection. In addition, samples showing a low S/CO ratio with an ID (Indeterminate) or negative RIBA result suggest a high probability of nonspecific reactivity in ELISA.