title: SAMBA HIV semiquantitative test, a new point-of-care viral-load-monitoring assay for resource-limited settings.
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.
authors.affiliation: Diagnostic Development Unit, Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Allyson V
authors.initials: AV
authors.lastname: Ritchie
authors.affiliation: Barts and The London NHS Trust, London, United Kingdom.
authors.forename: Ines
authors.initials: I
authors.lastname: Ushiro-Lumb
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Edemaga
authors.affiliation: Diagnostic Development Unit, Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Hrishikesh A
authors.initials: HA
authors.lastname: Joshi
authors.affiliation: Department of Genitourinary Medicine and HIV, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.
authors.forename: Annemiek
authors.initials: A
authors.lastname: De Ruiter
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Szumilin
authors.affiliation: Department of Genitourinary Medicine and HIV, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Jendrulek
authors.affiliation: Médecins Sans Frontières, Paris, France.
authors.forename: Megan
authors.initials: M
authors.lastname: McGuire
authors.affiliation: Diagnostic Development Unit, Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Neha
authors.initials: N
authors.lastname: Goel
authors.affiliation: Diagnostic Development Unit, Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Pia I
authors.initials: PI
authors.lastname: Sharma
authors.affiliation: Division of Transfusion Medicine, Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Allain
authors.affiliation: Diagnostic Development Unit, Department of Haematology, University of Cambridge, Cambridge, United Kingdom hl207@cam.ac.uk.
authors.forename: Helen H
authors.initials: HH
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D008131:London; D008295:Malawi; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D014454:Uganda; D006113:United Kingdom; D019562:Viral Load / Q000379:methods*; D055815:Young Adult