Abstract
Background: Fourth-generation HIV assays detect both antigen and antibody, facilitating detection of acute/early HIV infection. The Bio-Rad GS HIV Combo Ag/Ab assay (Bio-Rad Combo) is an enzyme immunoassay that simultaneously detects HIV p24 antigen and antibodies to HIV-1 and HIV-2 in serum or plasma. Objective: To evaluate the performance of the Bio-Rad Combo assay for detection of HIV infection in adults from Southern Africa. Study design: Samples were obtained from adults in Soweto and Vulindlela, South Africa and Dar es Salaam, Tanzania (300 HIV-positive samples; 300 HIV-negative samples; 12 samples from individuals previously classified as having acute/early HIV infection). The samples were tested with the Bio-Rad Combo assay. Additional testing was performed to characterize the 12 acute/early samples. Results: All 300 HIV-positive samples were reactive using the Bio-Rad Combo assay; false positive test results were obtained for 10 (3.3%) of the HIV-negative samples (sensitivity: 100%, 95% confidence interval [CI]: 98.8-100%); specificity: 96.7%, 95% CI: 94.0-98.4%). The assay detected 10 of the 12 infections classified as acute/early. The two infections that were not detected had viral loads. <. 400. copies/mL; one of those samples contained antiretroviral drugs consistent with antiretroviral therapy. Conclusions: The Bio-Rad Combo assay correctly classified the majority of study specimens. The specificity reported here may be higher than that seen in other settings, since HIV-negative samples were pre-screened using a different fourth-generation test. The assay also had high sensitivity for detection of acute/early infection. False-negative test results may be obtained in individuals who are virally suppressed.
Original language | English (US) |
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Pages (from-to) | 75-79 |
Number of pages | 5 |
Journal | Journal of Clinical Virology |
Volume | 62 |
DOIs | |
State | Published - Jan 1 2015 |
Keywords
- Africa
- Diagnosis
- Enzyme immunoassay
- Fourth-generation
- HIV
ASJC Scopus subject areas
- Virology
- Infectious Diseases