Low cost molecular assay for HIV
Small Business Information
BIOHELIX CORPORATION, 32 TOZER RD, BEVERLY, MA, 01915
AbstractDESCRIPTION (provided by applicant): We propose to develop a rapid, low cost, threshold assay for the detection of HIV infection of HIV vaccination trial participants. Infection by HIV, and viral load are the usual end points for Phase III HIV vaccination trials. Ongoing Phase III HIV vaccine trials require a simple, and low cost molecular diagnostic test that can detect HIV infection in immunized participants. Indeed, current molecular tests are too complex to be used for screening purposes, immunoassays cannot distinguish between immunization and infection, and CD4 cell counts are unlikely to detect early HIV infection. Although FDA requires the use an approved assay to measure viral load in order to meet the demands for licensure, a low cost, moderate co mplexity, screening test will greatly facilitate these trials. Indeed all participants in both the placebo and vaccine arms must be screened periodically (e.g., at 3 to 6 month intervals). The assay we propose to develop will use our proprietary helicase d ependent amplification (HDA) platform as well as a low cost device specifically designed to perform molecular tests without contaminating the laboratory with amplification products. HDA is similar to the polymerase chain reaction (PCR) in that it uses two primers to exponentially amplify nucleic acids. It is distinct from PCR in that it is entirely isothermal (and thus does not require costly thermocyclers). We propose to use simulated clinical samples generated with the Armored RNA HIV Quant clone spiked i nto whole blood from HIV seronegative volunteers at known concentrations. Armored RNA will be isolated from plasma prior to RT-HDA testing. Lateral flow devices have already proven their utility in separating nucleic acid amplification products, and are wi dely used in several moderate complexity and CLIA-waived tests listed in the FDA device database. Detection of amplicons will be accomplished by using latex particles conjugated to antibodies that bind to the probes used to detect the HDA reaction produc ts. The assay uses a sandwich format to detect haptens (biotin, FITC and Digoxigenin) incorporated into one of the HDA primers and into each of the detection probes. The lateral flow strip used for these assays has two capture zones, and thus allows for th e detection of one analyte (HIV) as well as a competitive internal control. Assays that fail to give a band in the lateral flow device window are scored as invalid, while assays with a band in the control line alone are scored as true negative. Assays with bands at both the control and test line position are scored as positives at the threshold value (typically 50 copies of the analyte). Assays with a strong band in the test line but no control line are scored as strong positives (typically over 5000 copies of analyte). We will test the specificity and sensitivity of the HIV test with clinical specimens at Vanderbilt University. Kits will be supplied to Dr. Yi-Wei Tang (Vanderbilt University) so his laboratory can evaluate the assays. We may also supply kits to US Government labs that want to try the test. We will also contract with Assuragen to engineer a clone of Armored RNA for our competitive internal control. Finally, we will compare the performance of HDA and the Roche Amplicor HIV-1 DNA PCR (version 1. 5) using a set of Dried Blood Spot (DBS) specimens from the CDC's Proficiency Testing (PT) Program. By the end of Phase I, we will have preliminary data for submission of a pre-IDE to the FDA to kick-off a clinical study to seek regulatory clearance for sa le of the assay system for human diagnostics using the Roche Amplicor HIV-1 DNA PCR (version 1.5) assay as a predicate device.Narrative More than 90 % of the 40 million human immunodeficiency virus (HIV)-infected persons live in Third World countries (see www.unaids.org/bangkok2004/GAR2004_html/GAR2004_03_en.htm). An HIV vaccine is the lowest cost medical solution for containing the acquired immuno deficiency
* information listed above is at the time of submission.