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Comparative Study
. 2014 Sep;52(9):3377-83.
doi: 10.1128/JCM.00593-14. Epub 2014 Jul 16.

SAMBA HIV semiquantitative test, a new point-of-care viral-load-monitoring assay for resource-limited settings

Allyson V Ritchie  1 , Ines Ushiro-Lumb  2 , Daniel Edemaga  3 , Hrishikesh A Joshi  1 , Annemiek De Ruiter  4 , Elisabeth Szumilin  3 , Isabelle Jendrulek  4 , Megan McGuire  3 , Neha Goel  1 , Pia I Sharma  1 , Jean-Pierre Allain  5 , Helen H Lee  6
Affiliations
Comparative Study

SAMBA HIV semiquantitative test, a new point-of-care viral-load-monitoring assay for resource-limited settings

Allyson V Ritchie et al. J Clin Microbiol. 2014 Sep.

Abstract

Routine viral-load (VL) testing of HIV-infected individuals on antiretroviral therapy (ART) is used to monitor treatment efficacy. However, due to logistical challenges, implementation of VL has been difficult in resource-limited settings. The aim of this study was to evaluate the performance of the SAMBA semi-Q (simple amplification-based assay semiquantitative test for HIV-1) in London, Malawi, and Uganda. The SAMBA semi-Q can distinguish between patients with VLs above and below 1,000 copies/ml. The SAMBA semi-Q was validated with diluted clinical samples and blinded plasma samples collected from HIV-1-positive individuals. SAMBA semi-Q results were compared with results from the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 test, v2.0. Testing of 96 2- to 10-fold dilutions of four samples containing HIV-1 subtype C as well as 488 samples from patients in the United Kingdom, Malawi, and Uganda yielded an overall accuracy for the SAMBA semi-Q of 99% (95% confidence interval [CI], 93.8 to 99.9%) and 96.9% (95% CI 94.9 to 98.3%), respectively, compared to to the Roche test. Analysis of VL data from patients in Malawi and Uganda showed that the SAMBA cutoff of 1,000 copies/ml appropriately distinguished treated from untreated individuals. Furthermore, analysis of the viral loads of 232 patients on ART in Malawi and Uganda revealed similar patterns for virological control, defined as either <1,000 copies/ml (SAMBA cutoff) or <5,000 copies/ml (WHO 2010 criterion; WHO, Antiretroviral Therapy for HIV Infection in Adults and Adolescents: Recommendations for a Public Health Approach, 2010). This study suggests that the SAMBA semi-Q has adequate concurrency with the gold standard measurements for viral load. This test can allow VL monitoring of patients on ART at the point of care in resource-limited settings.

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Figures

FIG 1
FIG 1
SAMBA semi-Q system. (A) SAMBAprep (right) and SAMBAamp (left) instruments. (B) SAMBAamp cartridge showing results for (i) >1,000 and (ii) <1,000 copies/ml and (iii) invalid results.
FIG 2
FIG 2
Field testing algorithm for the SAMBA semi-Q with 354 samples collected in Malawi and Uganda and summary of results. All samples were tested with the SAMBA semi-Q and Roche TaqMan v2. Twelve samples were discrepant between SAMBA and Roche and were tested with Abbott RealTime. Ten of the 12 samples were discrepant between SAMBA and Abbott, and two were discrepant between Abbott and Roche.
FIG 3
FIG 3
Distribution of VL among 284 patients receiving ART and 70 untreated individuals in Malawi and Uganda. VL was determined with Roche TaqMan v2.
FIG 4
FIG 4
Virological suppression according to the SAMBA semi-Q cutoff and 2013 WHO guidelines (1,000 copies/ml [8]) or 2010 WHO guidelines (5,000 copies/ml [17]) in 232 patients on ART for various numbers of years in Uganda and Malawi.
See this image and copyright information in PMC

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