ExaVir™ Load - Cavidi

For analyzing the activity of the enzyme RT from lentivirus.

ExaVir™ Load

Near-patient HIV Viral Load Monitoring

Provides clinicians with a clearer view of disease progression, therapeutic compliance, and the emergence of drug resistance for HIV viral load testing.

ExaVir Load is available today for reliable near-patient viral load testing. It is currently being used for clinical testing in many environments from Myanmar to Zimbabwe. Contact us if you need to decentralize your viral load testing program.

Since its first release in 2002, ExaVir Load has been continually developed to make it more accurate, more reliable and more accessible to healthcare providers. From major urban research hospitals in London to small rural clinics in Botswana, ExaVir Load has established a new level of accuracy and reliability for HIV viral load testing. It provides clinicians with a clearer view of disease progression, therapeutic compliance, and the emergence of drug resistance. Just as important, ExaVir Load provides patients with greater access to proper HIV viral load monitoring because it is an affordable, near-patient solution that can be run in virtually any clinic.

Proven reliability

There is no shortage of ideas on how to measure HIV viral load. However, few succeed in making the transition from theory into practice. After a decade in the field, more than 40 peer-reviewed journal articles, and over 350,000 tests run, ExaVir Load’s reliability is well-proven. To see how ExaVir Load compares to other options, check this HIV Viral Load Monitoring Comparison Infographic created by the Load Zero Foundation.


Assessment of the Cavidi ExaVir Load Assay for Monitoring Plasma Viral Load in HIV-2-Infected Patients.

Authors: Borrego P, Gonçalves MF, Gomes P, Araújo L, Moranguinho I, Figueiredo IB, Barahona I, Rocha J, Mendonça C, Cruz MC, Barreto J, Taveira N.

Journal: Journal of Clinical Microbiology, 2017, 55 (8) 2367-2379

Product usage: The aim of this study was to make the first clinical evaluation of Cavidi ExaVir™ Load version 3.0 in HIV-2 infected patients. HIV-2 viral load was quantified by both ExaVir and an in-house real-time quantitative PCR. There was no difference between the methods in the capacity to discriminate between non-quantifiable and quantifiable HIV-2 in the plasma. In samples with quantifiable HIV-2 viral load by both methods, the measurements were highly correlated (Pearson r=0.908). In conclusion, ExaVir Load version 3.0 is a reliable commercial assay to measure viral load on HIV-2 infected patients and, therefore, a valuable alternative to the in-house assays in current use.


The performance of reverse transcriptase assay for the estimation of the plasma viral load in HIV-1 and HIV-2 infections,

Authors: Padaki PA, Sachithanandham J, Isaac R, Ramalingam VV, Abraham OC, Pulimood SA & Kannangai R.

Journal: Infectious Diseases, (2016) 48:6, 467-471.

Product usage: This study compares the performance of ExaVir™ version 3.0 with molecular HIV viral load assays. 125 HIV-1 and 13 HIV-2 positive samples were analyzed. The overall sensitivity of the assay was 86.8% and 94.1% for viral load >1000 copies/ml measured by Qiagen Artus HIV-1 RG RT PCR and Abbott RealTime HIV-1 PCR assays. Among the 13 HIV-2 samples, 9 were positive by Cavidi version 3.0. All HIV-negative, HBV-positive, and HCV-positive samples were negative and the assay proved to be very specific for HIV.


Can HIV reverse transcriptase activity assay be a low-cost alternative for viral load monitoring in resource-limited settings?

Authors: Gupta S, Palchaudhuri R, Neogi U, et al.

Journal: BMJ Open 2016; 6:e008795.

Product usage: Performance and cost of an HIV-RT assay (ExaVir™ Load version 3.0) were compared to a HIV-1 RNA assay (Abbott m2000rt) in a cohort of 327 Indian patients before and 4 weeks after initiation of first-line therapy. A strong correlation (r=0.96) was observed. Bland-Altman analysis showed a good level of agreement with a mean difference (bias) of 0.22 log10 copies/mL. The performance of ExaVir Load version 3.0 was not negatively affected by a nevirapine/efavirenz based antiretroviral regimen. The per test cost of measuring plasma viral load by the Abbott m2000rt and ExaVir Load version 3.0 assays in a basic lab setting was $36.4 and $16.8, respectively.


Monitoring the efficacy of antiretroviral therapy by a simple reverse transcriptase assay in HIV-infected adults in rural Vietnam.

Authors: Cuong DD, Agneskog E,Chuc NT, Santacatterina M, Sönnerborg A, Larsson M.

Journal: Future Virology September 2012, Vol. 7, No. 9, Pages 923-931

Product usage: Aim: To determine the feasibility of viral load (VL) monitoring using ExaVir™ Load in a cohort of 605 HIV treatment-naive adult patients initiating antiretroviral therapy in rural Vietnam. Materials & methods: VL monitoring every 6 months, survival and intention-to-treat analysis were used. Roche Cobas TaqMan® VL was compared with ExaVir Load using Spearman’s rank correlation coefficient and Bland–Altman analysis.


HIV reverse transcriptase activity assay: a feasible surrogate for HIV viral load measurement in China.

Authors: Huang D, Zhuang Y, Zhai S et al.

Journal: Diagn Microbiol Infect Dis. 2010 Nov;68(3):208-13.

Product usage: The quantitation of HIV viral load using an assay that measures the activity of reverse transcriptase (RT) may provide an alternative strategy for the monitoring of HIV viral load within resource-limited areas in China. Plasma viral load analyses of 215 samples from 87 patients infected with HIV were detected using the RT activity assay (ExaVir Load versions 2 and 3; Cavidi, Uppsala, Sweden) and RT polymerase chain reaction (PCR) (COBAS TaqMan 48, Amplink version 3.2; Roche Molecular Systems, Branchburg, NJ). The RT activity assay versions 3 (RT3) and 2 (RT2) could detect 95.3% and 86.9% of samples with measurable RNA by RT-PCR, respectively. […]


Evaluation of the Cavidi ExaVir Load version 3 assay for plasma HIV-1 viral load monitoring.

Authors: Greengrass VL, Plate MM, Steele PM, Denholm JT, Cherry C, Morris LM, Hearps A, Crowe SM.

Journal: J Clin Microbiol. 2009 Sep;47(9):3011-3.

Product usage: We evaluated the new low-cost ExaVir Load (version 3) reverse transcriptase viral load assay against the Roche Cobas Amplicor assay. Results for samples tested using the reverse transcriptase assay correlated well with those obtained with the Roche assay (r = 0.85; n = 202). The version 3 reverse transcriptase assay shows improved sensitivity compared to the previous version.


Comparative evaluation of the ExaVir Load version 3 reverse transcriptase assay for measurement of human immunodeficiency virus type 1 plasma load.

Authors: Labbett W et al.

Journal: J Clin Microbiol. 2009 Oct;47(10):3266-70. Epub 2009 Aug 5.

Product usage: The objective of this study was to evaluate the performance of the ExaVir Load version 3 assay (referred to hereafter as the ExaVir assay) in comparison to two real-time PCR assays widely used in high-income countries: the Abbott M2000sp/M2000rt RealTime human immunodeficiency virus type 1 (HIV-1) assay (referred to as the RealTime assay) and the Roche COBAS-Ampliprep/COBAS-TaqMan HIV-1 version 1 assay (referred to as the TaqMan assay). […] The ExaVir assay showed excellent concordance with real-time molecular assays, offering a suitable option for virological monitoring in settings with limited infrastructure.

PCT/SE002/00612 (WO 02/082088)

Recovery of enzyme activity from enveloped viruses

OAPI 12460, South Africa 2003/7413, Eurasia 006740, China 02811088, Australia 2002249715. ARIPO Ap 1823 01/2008. EP1373897, Mexico PA/a/2003/009060, Hong Kong HK106307, US 7566592B2, Japan 4364512, India 240235, Brazil PI 0208542-9 2014/07, Thailand 41834

PCT/SE01/00617 (WO 01/75147)

Method of concentrating and recovering a viral enzyme activity from biological samples

China ZL01807159.7, EP 1268851, Hong Kong 03104711.7; India 206207, US 7833700 , Brazil PI 0109674-5 Jan 2014