Human Immunodeficiency Virus (HIV) Reverse Transcriptase Activity Correlates with HIV RNA Load: Implications for Resource-Limited Settings

Abstract

Measurement of human immunodeficiency virus type 1 (HIV-1) plasma RNA levels using Roche AMPLICOR version 1.5 (HIV RNA) is an integral part of monitoring HIV-infected patients in industrialized countries. These assays are currently unaffordable in resource-limited settings. We investigated a reverse transcriptase (RT) assay as a less expensive alternative for measuring viral burden that quantifies RT enzyme activity in clinical plasma samples. A comparison of RT and HIV RNA assays was performed on 29 paired plasma samples from patients living in the United States and 21 paired plasma samples from patients living in Cameroon. RT levels correlated significantly with plasma HIV RNA viral loads in plasma from U.S. patients (r ‫؍‬ 0.898; P < 0.001) and Cameroonian patients, a majority of whom were infected with HIV-1 clade type CRF02_AG (r ‫؍‬ 0.669; P < 0.01). Among 32 samples with HIV viral load of >2,000 copies/ml, 97% had detectable RT activity. One Cameroon sample had undetectable RNA viral load but detectable RT activity of 3 fg/ml. The RT assay is a simple and less expensive alternative to the HIV RNA assay. Field studies comparing these assays in resource-limited settings are warranted to assess the practicality and usefulness of this assay for monitoring HIV-infected patients on antiretroviral therapy.Human immunodeficiency virus (HIV) plasma viral load measurement is an integral part of monitoring infected patients in industrialized countries to determine the need to initiate or change antiretroviral (ARV) therapy. A commonly used Food and Drug Administration-approved assay, the Roche AMPLICOR version 1.5 (HIV RNA), is unaffordable for most patients in resource-limited settings. This HIV RNA assay uses nucleic acid amplification by PCR of conserved gene sequences, including non-clade B sequences (4, 9). One alternative to measuring RNA copies is to measure the activity of the virus-encoded reverse transcriptase enzyme (RT). An RT assay kit, ExaVir Load version 2, is currently available and distributed in Africa, but no published studies to date have correlated version 2 of the RT assay with HIV RNA viral load. We describe this correlation in plasma samples from HIVinfected patients from New York and Cameroon. MATERIALS AND METHODSPlasma samples from HIV-infected patients in New York City and Cameroon. New York City. Twenty-nine anonymous plasma samples from HIV-infected persons attending New York University Medical Center in 2004 were studied. Specimens were presumed to contain predominantly clade B HIV-1 virus, although clade analysis was not performed on these samples. While information on clinical symptoms or antiretroviral therapy history was not available for this anonymous sample, a large proportion of patients attending this clinic receive antiretroviral therapy. All samples were processed within 6 h and stored at Ϫ70°C.Cameroon. Twenty-one anonymous plasma samples from Bamenda, Cameroon, were obtained as part of a larger study (3). All patients were antiretroviral treatment naïve. Blood was collecte...

Establishment of In-House Quantitative Real-Time RT-PCR Assay for HIV-1 Viral Load Measurement: Application to Evaluate Efficacy of ART in Ghanaian Patients in an Urban Setting

“…CRF02_AG is the major driver of HIV infection in Ghana and others in minor proportion of circulation such as CRF06_cpx, sub-subtype A3, CRF09_cpx and subtypes A, G and D had been identified. Studies have shown that RT activity is independent of the HIV-subtype [40][41][42][43][44][45]. This is in agreement with other studies that evaluated an in-house real-time RT-PCR assay that targeted the same Long Terminal Repeat (LTR) region probing for viral RNA.…”

Low-cost tools for diagnosing and monitoring HIV infection in low-resource settings

“…28 As such, commercial assays for measuring this protein are cheap alternatives for virus load monitoring in low-resource settings. These tests are not performed at the point of care, but they yield results in a few hours and cost 80% less than nucleic acid tests.…”

“…Further advantages of reverse transcriptase tests include their ability to detect multiple subtypes of HIV and their possible use in monitoring HIV load in paediatric patients. 29 Levels of the HIV core protein p24 also correlate with HIV load and CD4+ T-cell count, 28 and thus early generation p24 immunoassays offered low-cost options for measuring HIV load. p24 immunoassays are no longer considered for this activity, however, because of their low sensitivity, the high variability of the results between assays and the difficulty in standardizing the correlation between p24 and virus load in persons receiving ART.…”

Detection of HIV-1 P24 Gag in Plasma by a Nanoparticle-Based Bio-Barcode-Amplification Method

“…Detection of the major core protein of HIV-1 (p24 Gag) in serum or plasma by an ELISA is specific but does not offer the requisite sensitivity [5,6,[18][19][20][21]. Other methods for assessing the presence of virus include PCR-based detection of the viral genome, specific primers and probes in plasma and viral co-culture with normal donor lymphocytes [3,7,8,16]. Although accurate, these techniques are time-consuming and require specialized laboratories, elaborate equipment, special specimen-transport conditions to maintain viability and highly skilled personnel.…”

“…Commonly used methods rely on the detection of antibodies to HIV-1 in plasma or sera [2,[7][8][9]. Unfortunately, these techniques are of little value in the earliest stages of infection before the development of antibodies against HIV-1 (average infectious-window period of 25 days; 95% confidence interval: 9-41 days) [10][11][12][13][14] and also in neonates because maternal antibodies can persist in the newborn for up to 12 months or more [5,[15][16][17].…”