665 Plasma RNA Quantification and HIV-1-Divergent Strains M. Gueudin*1, J. C. Plantier1, F. Damond2, J. Braun1, P. Roques5, P. Mauclère3,4, F. Simon1 1Univ and Hosp, Rouen, France; 2Univ and Hosp Bichat, Paris, France; 3Inst Pasteur, Cameroun, France; 4Inst Pasteur, Madagascar; and 5Ctr Intl de Res Med de Franceville, Gabon
Background: The diversity of HIV complicates viral load measurement for patient management and treatment monitoring. Numerous studies have shown that non B group M variants can be underestimated, and that group O strains were not detected by commercial tests. More recent versions of these kits have improved the quantification of non B variants but are still unable to detect or correctly quantify group O strains. This lack of a quantitative tool particularly hinders the clinical management of HIV-O-infected patients.
Methods: In this study, we evaluated the new Abbott LCx RNA HIV QT viral load kit on a large collection of samples from Europe and central Africa. One hundred sixty group M samples, including 75 non B patients, and 70 group O samples (belonging to the 3 HIV-1 group O clades so far described O:A, O:B and O:C), were tested. The LCx system was compared to the Cobas Amplicor HIV-1 Monitor v1.5 test and to a quantitative real-time PCR method based on LightCycler technology, using primers selected in the highly conserved LTR and an HIV-1 group O-specific hydrolyze probe.
Results: LCx and Cobas had similar quantification ranges for group M samples, and a high degree of linearity (r2 = 0.9612). LCx efficiently quantified group O variants (31 of the 48 patients were quantifiable), and gave values within the range of those obtained with the LightCycler assay. The two assays were sensitive but showed only moderate linearity (r2=0.6195), probably owing to higher diversity of group O strains and to the use of primers and probe in different regions. Nevertheless, HIV-1 group O plasma load was high in the absence of treatment reaching similar values to those reported in HIV-1 group M infection.
Conclusions: The LCx or the LightCycler technology are adapted quantitative assays for the clinical management of group O infected patients. Overall, we found that the LCx kit reliably detected and quantified the different group M subtype.
