title: Use of an HIV-1 reverse-transcriptase enzyme-activity assay to measure HIV-1 viral load as a potential alternative to nucleic acid-based assay for monitoring antiretroviral therapy in resource-limited settings.
abstract: An inexpensive and technically less-demanding methodology to quantify HIV-1 viral load would be of great value for resource-limited settings, where the nucleic-acid amplification technique (NAAT) is impractical and/or resource-prohibitive. In this study, an HIV-1 reverse-transcriptase enzyme-activity assay (ExaVir Load assay, version 1) was compared with the gold standard RT-PCR assay, Roche HIV-1 Amplicor Monitor, version 1.5. A total of 121 plasma specimens were used for the evaluation. ExaVir Load had a sensitivity of 97 % and a specificity of 71 % in identifying specimens with <400 copies ml(-1) in the Roche RT-PCR assay as being less than the detection limit of the assay (5500 copies ml(-1)). The mean difference (95 % limits of agreement) between Roche RT-PCR and ExaVir Load was -0.23 (-1.59 to 1.13) log(10)(copies ml(-1)) by Bland-Altman analysis. Significant negative correlations were seen between CD4(+) T-cell counts and the ExaVir Load assay (r=-0.32, P<0.05), and between CD4(+) T-cell counts and the Roche RT-PCR (r=-0.38, P<0.01). The present study with HIV-1 showed a strong correlation between the ExaVir Load assay and the RT-PCR assay. Hence, the ExaVir Load assay could be considered for use in resource-limited settings as an alternative viral-load assay to the standard NAAT-based assay after further evaluation with prospective specimens.
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: H Syed
authors.initials: HS
authors.lastname: Iqbal
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: P
authors.initials: P
authors.lastname: Balakrishnan
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: Anitha J
authors.initials: AJ
authors.lastname: Cecelia
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: Suniti
authors.initials: S
authors.lastname: Solomon
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: N
authors.initials: N
authors.lastname: Kumarasamy
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: Vidya
authors.initials: V
authors.lastname: Madhavan
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: K G
authors.initials: KG
authors.lastname: Murugavel
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: Aylur K
authors.initials: AK
authors.lastname: Ganesh
authors.affiliation: YRG Centre for AIDS Research and Education (YRG CARE), Voluntary Health Services Hospital Campus, Taramani, Chennai-600113, India.
authors.forename: Sunil Suhas
authors.initials: SS
authors.lastname: Solomon
authors.affiliation: Brown University/Miriam Hospital, Providence, RI, USA.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Mayer
authors.affiliation: Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia.
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Crowe
mesh_terms: D023241:Antiretroviral Therapy, Highly Active / Q000706:statistics & numerical data; D016903:Drug Monitoring; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology; D054303:HIV Reverse Transcriptase / Q000032:analysis*; D015497:HIV-1 / Q000302:isolation & purification / Q000502:physiology*; D012367:RNA, Viral / Q000097:blood; D011933:Reagent Kits, Diagnostic; D021161:Self-Sustained Sequence Replication / Q000295:instrumentation* / Q000379:methods; D012680:Sensitivity and Specificity; D019562:Viral Load
chemical_list: D012367:RNA, Viral; D011933:Reagent Kits, Diagnostic; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase