Evaluation of AMPLILINK software for the COBAS AMPLICOR system

Laboratory evaluation of the Liat HIV Quant (IQuum) whole-blood and plasma HIV-1 viral load assays for point-of-care testing in South Africa

Point-of-care (POC) HIV viral load (VL) testing offers the potential to reduce turnaround times for antiretroviral therapy monitoring, offer near-patient acute HIV diagnosis in adults, extend existing centralized VL services, screen women in labor, and prompt pediatrics to early treatment. The Liat HIV Quant plasma and whole-blood assays, prerelease version, were evaluated in South Africa. The precision, accuracy, linearity, and agreement of the Liat HIV Quant whole-blood and plasma assays were compared to those of reference technologies (Roche CAP CTMv2.0 and Abbott RealTime HIV-1) on an HIV verification plasma panel (n = 42) and HIV clinical specimens (n = 163). HIV Quant plasma assay showed good performance, with a 2.7% similarity coefficient of variation (CV) compared to the Abbott assay and a 1.8% similarity CV compared to the Roche test on the verification panel, and 100% specificity. HIV Quant plasma had substantial agreement (pc [concordance correlation] = 0.96) with Roche on clinical specimens and increased variability (pc = 0.73) in the range of <3.0 log copies/ml range with the HIV Quant whole-blood assay. HIV Quant plasma assay had good linearity (2.0 to 5.0 log copies/ml; R(2) = 0.99). Clinical sensitivity at a viral load of 1,000 copies/ml of the HIV Quant plasma and whole-blood assays compared to that of the Roche assay (n = 94) was 100% (confidence interval [CI], 95.3% to 100%). The specificity of HIV Quant plasma was 88.2% (CI, 63.6% to 98.5%), and that for whole blood was 41.2% (CI, 18.4% to 67.1%). No virological failure (downward misclassification) was missed. Liat HIV Quant plasma assay can be interchanged with existing VL technology in South Africa. Liat HIV Quant whole-blood assay would be advantageous for POC early infant diagnosis at birth and adult adherence monitoring and needs to be evaluated further in this clinical context. LIAT cartridges currently require cold storage, but the technology is user-friendly and robust. Clinical cost and implementation modeling is required.

Feasibility of HIV point-of-care tests for resource-limited settings: challenges and solutions

Improved access to anti-retroviral therapy increases the need for affordable monitoring using assays such as CD4 and/or viral load in resource-limited settings. Barriers to accessing treatment, high rates of loss to initiation and poor retention in care are prompting the need to find alternatives to conventional centralized laboratory testing in certain countries. Strong advocacy has led to a rapidly expanding repertoire of point-of-care tests for HIV. point-of-care testing is not without its challenges: poor regulatory control, lack of guidelines, absence of quality monitoring and lack of industry standards for connectivity, to name a few. The management of HIV increasingly requires a multidisciplinary testing approach involving hematology, chemistry, and tests associated with the management of non-communicable diseases, thus added expertise is needed. This is further complicated by additional human resource requirements and the need for continuous training, a sustainable supply chain, and reimbursement strategies. It is clear that to ensure appropriate national implementation either in a tiered laboratory model or a total decentralized model, clear country-specific assessments need to be conducted.

Automation of laboratory testing for infectious diseases using the polymerase chain reaction-- our past, our present, our future

While it is an extremely powerful and versatile assay method, polymerase chain reaction (PCR) can be a labor-intensive process. Since the advent of commercial test kits from Roche and the semi-automated microwell Amplicor system, PCR has become an increasingly useful and widespread clinical tool. However, more widespread acceptance of molecular testing will depend upon automation that allows molecular assays to enter the routine clinical laboratory. The forces driving the need for automated PCR are the requirements for diagnosis and treatment of chronic viral diseases, economic pressures to develop more automated and less expensive test procedures similar to those in the clinical chemistry laboratories, and a shortage in many areas of qualified laboratory personnel trained in the types of manual procedures used in past decades. The automated Roche COBAS AMPLICOR system has automated the amplification and detection process. Specimen preparation remains the most labor-intensive part of the PCR testing process, accounting for the majority of the hands-on-time in most of the assays. A new automated specimen preparation system, the COBAS AmpliPrep, was evaluated. The system automatically releases the target nucleic acid, captures the target with specific oligonucleotide probes, which become attached to magnetic beads via a biotin-streptavidin binding reaction. Once attached to the beads, the target is purified and concentrated automatically. Results of 298 qualitative and 57 quantitative samples representing a wide range of virus concentrations analyzed after the COBAS AmpliPrep and manual specimen preparation methods, showed that there was no significant difference in qualitative or quantitative hepatitis C virus (HCV) assay performance, respectively. The AmpliPrep instrument decreased the time required to prepare serum or plasma samples for HCV PCR to under 1 min per sample. This was a decrease of 76% compared to the manual specimen preparation method. Systems that can analyze more samples with higher throughput and that can answer more questions about the nature of the microbes that we can presently only detect and quantitate will be needed in the future.