Objective To evaluate the performance of i3000 direct chemiluminescence detection of human immunodeficiency virus (HIV) antigen and antibody (Ag/Ab) screening assay (Maccura), compared with E170 electrochemiluminescence method (Roche, Elecsys® HIV Combi PT assay) and IS1200 indirect chemiluminescence method (Maccura). Methods Ten HIV seroconversion panels and 11 p24 antigen positive samples from West China Hospital of Sichuan University from April to December 2017 were used to evaluate the sensitivity of those three assays. A total of 351 samples were collected for consistency evaluation, including 350 HIV Ag/Ab test samples (200 HIV-1 positive plasma samples and 150 HIV 1+2 negative plasma samples) from West China Hospital of Sichuan University from April to December 2017, and one commercial HIV-2 sera. A total of 98 interfere samples for HIV testing were collected from West China Hospital of Sichuan University from April to December 2017. Results In the sensitivity evaluation, there were 63 samples from the 10 seroconversion panels, in which Roche E170 detected 25 samples, Maccura i3000 detected 23 samples, and Maccura IS1200 detected 22 samples; Maccura i3000 and Roche E170 assays detected all the p24 antigen positive samples (11, 100%), while Maccura IS1200 only detected 10 samples. In the consistency evaluation, Maccura i3000 had nice consistency with both Roche E170 and Maccura IS1200 (kappa>0.9, P<0.001). In the interference evaluation, there were two false positives in Maccura i3000 detection, one case of rheumatoid arthritis and one case of syphilis. Conclusion In addition to high throughput and good consistency, Maccura i3000 direct chemiluminescence reagent has high sensitivity and a short window period, which can meet clinical needs.
ObjectiveTo analyze the diagnostic efficacy of colloidal gold immunochromatography assay (GICA) in detection of SARS-CoV-2.MethodsUsing GICA detection kits from three different manufacturers, 33 serum samples were collected from 12 patients with SARS-CoV-2 infection at different time and 45 serum samples from 45 patients without SARS-CoV-2 infection were collected from West China Hospital of Sichuan University from January to February, 2020.ResultsThe sensitivity, specificity, positive predictive value and negative predictive value of the three GICA reagents were 66.7% - 90.9%, 73.3% - 100.0%, 71.4% - 100.0% and 80.4% - 91.7% respectively. The rates of missed diagnosis and misdiagnosis were 9.1% - 33.3% and 0 - 26.7%, respectively. The positive rate decreased with titer increasing. The interference factors mainly included human immunodeficiency virus infection, high rheumatoid factor blood samples, and hemolysis.ConclusionClinical laboratories should pay attention to the differences in the detection ability and potential cross-reaction of different reagents, or use a combination of multiple antibodies.
ObjectiveTo evaluate the clinical significance of human immunodeficiency virus (HIV) testing algorithm combining antigen/antibody assay screening with Western Blot (WB) or HIV nucleic acid.MethodsData of HIV antigen and antibody screening samples in West China Hospital of Sichuan University in 2018 were retrospectively analyzed. The 4th generation antigen and antibody reagents were used for initial screening, and the 3rd generation antibody reagents were used for reexamination. WB or HIV nucleic acid detection was performed as supplementary test.ResultsA total of 217 803 samples were initially screened, 718 samples were positive in initial screening (0.33%) and 513 samples were confirmed positive (0.24%). The 718 initial positive samples were confirmed by WB, among them, 513 (71.45%) were positive, 163 (22.70%) were negative, and 42 (5.85%) were indeterminate. Fifteen samples which were negative or indeterminate were detected by HIV RNA, as a result, 6 were positive. Two of four patients turned into positive during follow-up. Among the 536 samples which were positive in both the 4th and 3rd generation assay, there were 513 (95.71%) positive, 6 (1.12%) negative, and 17 (3.17%) indeterminate confirmed by WB; among the 182 samples which were positive in the 4th generation assay but negative in the 3rd generation assay, there were none (0.00%) positive, 157 (86.26%) negative, and 25 (13.74%) indeterminate confirmed by WB. The positive rate of confirmation test of samples positive in the 4th and 3rd generation assay (95.71%, 513/536) was significantly higher than that of samples positive in the 4th generation assay but negative in the 3rd generation assay (0%, 0/182), and the difference was statistically significant (χ2=610.091, P<0.001). WB band types for positive samples were dominated by the whole bands and sub-bands, accounting for 82.26%. The cut off index in ≥5 bands group was higher than that in < 4 bands group (P<0.001).ConclusionsSamples with both the 4th and 3rd generation assay positive have a high positive rate of confirmation test, and a supplementary test is needed to be done as soon as possible to confirm the diagnosis. Samples with only the 4th generation assay positive have a low positive rate of confirmation test. But for patients with a high-risk history, HIV nucleic acid should be done as soon as possible for early diagnosis.