238 Comparative Evaluation of the Performance of Abbott m2000rt Real-Time HIV-1 Assay for Measurement of HIV-1 Plasma Viral Load:

Background: Measurement of HIV-1 plasma viral load has become a corner stone in the clinical management particularly in the resource-limited settings. The objective of the present study is to evaluate the performance of recently introduced ABBOTT Real Time HIV-1 PCR assay (ABBOTT m2000rt) in comparison with the standard, COBAS Roche HIV-1 Monitor version 1.5 assay. Materials and Method: A total of 50 stored (−70°C) HIV-1 positive plasma samples with known viral copies/mL {<400 not detected (n = 10); <400 detected (n = 10); >400 - 5000 (n = 10); >5000 - 50000 (n = 10) and >50000 - 500000 (n = 10)} tested using the Roche HIV-1 Monitor ver. 1.5 assay and 20 HIV-1 low-risk seronegative (SN) samples were randomly used for the validation. Plasma RNA was extracted and concentrated using ABBOTT manual specimen preparation, which uses magnetic particle technology to capture nucleic acid extracted from 600 uL of plasma (detection range of 40- 100000 copies/mL). Plasma HIV-1 RNA levels were log10 transformed before being subjected to statistical analysis. Averages were statistically compared using the paired Z test. Linear regression and Bland-Altman were done to assess the agreement between these two assays. Results: The good correlation and agreement between ABBOTT Real Time and Roche was observed. Although the difference in viral load determinations was positively skewed in favor of the Roche assay, the difference in each PVL category, between the assays was within 0.5 log and the results were well correlated [R = +0.89 (P < 0.05)]. Bland-Altman analysis found 95% of the samples within clinically acceptable limits of agreement (−1.001 to 0.52 log copies/mL). The sensitivity and specificity of ABBOTT Real Time PCR detecting the viral copies of more than 1000/mL is 100% and >87%, respectively. The specificity of 100% by ABBOTT Real Time PCR with the testing of SN for HIV-1/2 plasma samples was observed. Conclusion: The new ABBOTT RealTime PCR plasma viral load assay is sensitive and meets the requirements for a wide dynamic range and providing higher throughput reliable quantification of HIV-1 RNA in plasma specimens.