The recent development of commercially-available assays using nucleic acid amplification test technologies (NAT) have made it possible for blood centers to consider applying these tests to blood donor screening. But NAT test systems, so far, are time intensive, require restricted laboratory space and highly-trained technical staff, and generally are unsuited to large-scale screening of donor samples. U.S. blood centers have adopted two basic """"""""pooling and pool resolution"""""""" strategies. One is a straight pool of 24 in which resolution of a """"""""reactive pool"""""""" requires testing individual samples. In the other strategy, smaller (intermediate) pools are prepared and combined to create a final (master) pool. Resolution of reactive master pools occurs by first testing the intermediate pools and then, if necessary, the individual samples. Pool size and pooling strategy balance assay sensitivity with the practical demands of assuring blood availability. Maxwell Sensors, Inc. (MSI) proposes to combine Helicase-Dependent Amplification (HDA) and Digital Magnetic Bead (DM-Bead) technologies to produce a one sample rapid, Simultaneous Assay for Multiple Pathogens in Blood (SAMP-B), in a high throughput 96-well microplate format. With a few drops of a donor's blood combined with DM-beads in a single microwell, it is possible to simultaneously identify HIV type 1 and 2, Hepatitis B (HBV), Hepatitis C (HCV), Human T- Lymphotropic Virus (HTLV type I and II), West Nile Virus (WNV), and many other blood-borne diseases. The DM-Bead, mass fabricated with digital bar codes by photolithography, then tagged with nucleic acid probes, are able to accurately identify many targets in a single homogeneous medium. The combined technology is very powerful and offers the following advantages: Sample pooling is not necessary: screening for multiple pathogens can be performed on an individual person's sample. Small quantity of sample: a few drops of blood in a microwell are all that's needed to identify multiple target pathogens. It not only determines a reactive sample, but also identifies """"""""reactive to what"""""""". Reduced window period: HDA offers high sensitivity and specificity without the """"""""window period"""""""" associated with antibody based screening technologies. Rapid and high throughput: simple isothermal operation and 96 patient samples can be performed on a single 96-well microplate. Flexibility: easy addition of new probes for additional screening targets on beads. Low cost, easy to use, and high reliability: DM-beads are low cost, simple operation steps, and batch to batch variation is minimal. During this project, we will focus on four key tasks: 1) design and fabrication of digital magnetic barcode beads, 2) design and construction of a detection system, 3) testing the DM-Bead-based multiplex HDA assay and 4) evaluation of system and bioassay performance.
Maxwell Sensors Inc. (MSI) proposes to develop a helicase-dependent amplification-based system, using digital magnetic barcoded beads that provide rapid, accurate, and easy-to-use screening for multiple blood-borne pathogens in small specimens of donor blood. This Simultaneous Assay for Multiple Pathogens in Blood will help blood banks and clinical laboratories to quickly test very large volumes of donated blood, and will help prevent the spread of blood-borne infections. The proposed technology that marries an advanced semiconductor fabrication process with molecular signature amplification and probing will allow high-throughput molecular diagnostic profiling of individuals at relatively low cost.
