Early Infant Diagnosis (EID) of HIV infection is key to ending the HIV pandemic. Currently, there is no HIV-1/HIV-2 qualitative assay for EID testing on high throughput testing systems from major manufacturers. The combination of confirmatory HIV testing and differentiation of heterotypic (HIV-1/2) and homotypic (HIV-1 or HIV-2) infections into one single test will provide clinicians with critical diagnostic data for personalized management of patients with HIV. This is particularly important in West African counties. Roche has developed the cobas HIV-1/HIV-2 Qualitative Test to detect and differentiate HIV-1/HIV-2 in dried blood spots (DBS). We report here the first independent performance evaluation of the test conducted at a College of American Pathologists accredited laboratory at the US CDC as part of the WHO prequalification of in vitro diagnostics process.
The evaluation used DBS created from HIV-negative whole blood spiked with cultured virus or with HIV-1 and HIV-2 RNA International WHO Standards. Prepared DBS were stored at -80°C until day of testing. Testing was performed on a cobas 6800 system (c6800) using the HIV-1/HIV-2 DBS Qual workflow and reagent kit. The limit of detection (LOD) was calculated using PROBIT analysis. The reproducibility, cross-contamination, subtype detection for HIV-1 A, B, C, D, CRF02-AG and for HIV-2, and error rate were also assessed.
The LOD for HIV-1 was 474 copies/mL (95% confidence interval: 162 – 2,550 copies/mL), and for HIV-2 was 1,136 copies/mL (683 – 3,062 copies/mL). Testing of forty replicates of three HIV-1 or HIV-2 samples over five days, by two testers with different reagent lots, showed 100% reproducibility. The five major HIV-1 subtypes evaluated were all detected. No cross-contamination was detected and the overall error rate was 0.48% among 409 tests performed.
This evaluation verified the manufacturer’s claims of analytical performance of the assay and provided valuable information for decision-making process related to approval for implementation in PEPFAR-supported countries. This is the first and only HIV-2 qualitative test commercially available on a high throughput HIV testing system. Clinical performance is currently being evaluated at PEPFAR-supported sites. The cobas HIV-1/HIV-2 Qualitative Test on the c6800 for HIV EID combines the capability of confirmatory HIV infection and HIV-1/HIV-2 differentiation, which will prove to be a useful tool in combating HIV.