Correlation of S/CO value in ELISA and RNA level with positive result of human immunodeficiency virus antibody in confirmatory test

Objective: To investigate the correlation of S/CO value in ELISA and RNA level with the positive result of human immunodeficiency virus (HIV) in confirmatory test. Methods: A total of 86 preliminarily screened anti-HIV positive samples were analyzed by ELISA using two domestic (Wantai and Kehua) and one imported (Bio-Rad) kits for HIV antigen and antibody, by RT-PCR-fluorescent probe method using one RNA determination kit, and by Western blot using WB confirmatory kit, and the relationship of result was analyzed. Results: Of the 86 samples, 53 anti-HIV positive ones judged by three ELISA kits were confirmed as positive by Western blot. However, of the 25 negative samples judged by three ELISA kits, 20 were confirmed as negative by Western blot, while 5 as uncertain. Of the 8 samples with inconsistent ELISA results, 3 were confirmed as uncertain, while 5 as negative, by Western blot. Of the samples with S/CO values of not less than 10 judged by Wantai and Kehua kits, 96.30% and 100% were confirmed as positive by Western blot. However, of the samples with S/CO values of not less than 1 but less than 10, 20% were confirmed as positive by Western blot. All the samples with S/CO value of not less than 5 judged by Bio-Rad kit were confirmed as positive by Western blot. Of the samples with RNA level of not less than 103 IU/ml, 97.87% were confirmed as positive by Western blot. However, of the samples with RNA level of less than 10 3 IU/ml, only 53.85% were confirmed as positive by Western blot. Of the 15 samples with incomplete results in ELISA and RNA quantitation test, 4 were judged as positive by RNA quantitation test and confirmed as uncertain by Western blot, which were defined as suspected HIV-1 infection. Conclusion: The S/CO value in ELISA and RNA level of anti-HIV showed a certain correlation with positive results in confirmatory test, which provided a certain reference for judgment of positive result in confirmatory test.