Hologic Gen-Probe is dedicated to developing and in-licensing innovative technologies that help our customers improve human health. Our technologies are used daily to diagnose diseases, protect the World's supply of donated blood, and ensure transplant compatibility. We have been awarded more than 500 patents around the world that underpin the process of molecular diagnostics testing.
Transcription-Mediated Amplification (TMA) Technology
The goal of amplification technologies is to produce millions of copies of the target nucleic acid sequences that are present in samples in small numbers, which can then be detected using DNA probes. Amplification technologies can yield results in only a few hours versus the several days or weeks required for traditional culture methods. Our patented TMA technology is designed to overcome problems faced by other target amplification methods. TMA is a transcription-based amplification system that uses two different enzymes to drive the process. The first enzyme is a reverse transcriptase that creates a double-stranded DNA copy from an RNA or DNA template. The second enzyme, an RNA polymerase, makes thousands of copies of the complementary RNA sequence known as the 'RNA amplicon', from the double-stranded DNA template. Each RNA amplicon serves as a new target for the reverse transcriptase and the process repeats automatically, resulting in an exponential amplification of the original target that can produce over a billion copies of amplicon in less than 30 minutes.
Detection of target organisms that are present in small numbers in a large-volume clinical sample requires that target organisms be concentrated to a detectable level. One way to accomplish this is to isolate the particular nucleic acid of interest by binding it to a solid support, which allows the support, with the target bound to it, to be separated from the original sample. We refer to such techniques as 'target capture'. We have developed target capture techniques to immobilize nucleic acids on magnetic beads by the use of a 'capture probe' that attaches to the bead and to the target nucleic acid. We use a magnetic separation device to concentrate the target by drawing the magnetic beads to the sides of the sample tube, while the remainder of the sample is washed away and removed. When used in conjunction with our patented amplification methods, target capture techniques concentrate the nucleic acid target(s) and also remove materials in the sample that might otherwise interfere with amplification.
Hybridization Protection Assay (HPA) and Dual Kinetic Assay (DKA) Technologies
With our patented HPA technology, we have simplified testing, further increased test sensitivity and specificity, and increased convenience. HPA has enabled us to produce the first NAT assay that did not require the cumbersome wash steps needed with conventional probe tests and immunoassays. In the HPA process, the acridinium ester, or AE, molecule is protected within the double-stranded helix that is formed when the probe binds to its specific target. Prior to activating the AE molecule, known as 'lighting-off', a chemical is added that destroys the AE molecule on any unhybridized probes, leaving the label on the hybridized probes largely unaffected. When the 'light-off' or detection reagent is added to the specimen, only the label attached to the hybridized probe is left to produce a signal indicating that the target organims's DNA or RNA is present. All of these steps occur in a single tube and without any wash steps, which were required as part of conventional probe tests. Our DKA technology uses two types of AE molecules, one that 'flashes' and another that 'glows'. By using DKA, we have created NAT assays that can detect two separate targets simultaneously.
Ribosomal RNA Targeting
We have developed and patented a technique that detects and identifies organisms by targeting their rRNA. Each bacterial cell contains up to 10,000 copies of rRNA, as compared with only a few copies of DNA. Most of our competitors' NAT assays target DNA. But by using a probe that hybridizes to rRNA, the sensitivity of our tests can be increased thousands of times. The high number of rRNA targets also offers advantages when amplification is used. When small numbers of organisms are present in a sample, they may not be present in the portion of the sample used for the assay. This would result in a negative test result. By breaking open the organism prior to sampling, the multiple copies of rRNA targets are dispersed throughout the sample and the likelihood of detecting them is increased many fold. Thus, the likelihood of obtaining a false negative result is much less than when DNA is targeted. Finally, rRNA molecules naturally exist as single strands that can directly hybridize with our nucleic acid probes. This contrasts to most DNA targets, which exist as double strands that must be separated before a probe can bind. These separated DNA strands tend to hybridize to each other rather than to the DNA probe, thus limiting the amount of DNA probe that can bind and the overall sensitivity of the test.
Based on our expertise in hardware and software engineering, we have developed instrument platforms that offer superior automation and workflow for our customers. For example, we have commercialized the TIGRIS instrument, the world's first and only fully automated, integrated, high-throughput, molecular diagnostics instrument system. Launched in 2004, the TIGRIS instrument significantly reduces labor costs and contamination risks in high-volume diagnostic testing environments, and enables large blood screening centers to individually test donors' blood. The TIGRIS system is used by customers to perform our APTIMA women's health products, as well as the PROCLEIX ULTRIO and West Nile virus assays for blood screening.
We are building on the success of the TIGRIS system by developing a new automated instrument platform, called the PANTHER system. We believe the PANTHER system, which is designed for low- to mid-volume customers, will be a pillar in our future instrumentation platform strategy. We believe that the use of automated instrumentation, such as our TIGRIS system and our developmental PANTHER instrument, will facilitate growth in both clinical diagnostics and blood screening.
We have been issued more than 70 patents around the world in recognition of our pioneering work in molecular diagnostics automation.
Nucleon DNA Extraction
Nucleon® is a patented DNA extraction technology designed to provide high yields of high quality DNA from a range of sample matrices including whole blood, cell cultures, hard/soft tissue, mouse tails and plant material. Unlike many other DNA purification technologies, Nucleon does not involve binding of the DNA to a solid phase at any stage. Instead, the DNA is isolated by sequential processes of partition facilitated by centrifugation and is cleaned by binding impurities to a proprietary resin. This procedure, combined with gentle mixing, promotes the recovery of high yields of very high molecular weight, pure DNA. No phenol is involved in the procedure, minimising the hazard, and cost, of waste handling.
ARMS or Amplification Refractory Mutation System is a modification of the Polymerase Chain Reaction (PCR) that enables allele specific discrimination. The method utilises the inability of Taq polymerase to extend a mismatched DNA target sequence at its 3' end in PCR amplification. ARMS primers are designed such that their 3' ends either match or mismatch target DNA sequences resulting in either PCR amplification or no PCR amplification. The ARMS technique has a high sensitivity and specificity of detection of nucleotide changes, insertions and deletions in target DNA sequence. ARMS primers can be highly multiplexed so that simultaneous amplification of multiple target sequences can occur in a single tube, coupled with fluorescent labelling technologies enables highly informative assays analysed in a moderate laboratory throughput.
QF-PCR or Quantitative Fluorescent PCR is a technique used for chromosome copy number (or aneuploidy) analysis. Short Tandem Repeats (STR's) are small but highly variable sections of DNA that are repeated throughout the genome. The QF-PCR technique specifically analyses these STR sequences by fluorescently labelling and measuring the number of repeats (or length). Analysis of STR markers that are specific to certain chromosomes enables a measure of the number of copies of that chromosome. In normal individuals there are 2 copies of each chromosome (apart from the sex chromosomes X and Y) i.e. one of paternal origin and one of maternal origin. The detection of 2 STR markers in equal quantity confirms a normal result. Detection of an imbalance of the normal 1:1 STR marker ratio or the presence of three copies of an STR marker (i.e. 1:1:1) indicate a trisomy which is the presence of three copies of a particular chromosome. The most frequent human trisomy is a trisomy of chromosome 21 which results in Down Syndrome. The QF-PCR technique is used in Hologic Gen-Probe's Elucigene QST*R kits for the detection of chromosome aneuploidy of chromosomes 13,18,21,X and Y. QF-PCR is a DNA based method for rapid analysis of chromosome copy number and is routinely used in pre-natal diagnosis of mothers that have been identified as a high risk of carrying a Down Syndrome fetus through biochemical and ultrasound screening. A QF-PCR test can confirm the diagnosis within 48 hours, much quicker than karyotyping which can take up to 2 weeks.
The Prodesse assays are based on Real Time PCR and Taqman reagent chemistry, which utilizes the 5' - 3' exonuclease activity of the Taq polymerase to cleave the probe thus separating the reporter dye from the quencher. This generates an increase in fluorescent signal with each cycle and is dependent on the amount of amplification products present at the time. Fluorescent intensity is monitored during each PCR cycle by the real-time instrument.
Luminex xMAP Technology
Luminex color-codes tiny beads, called microspheres, into 100 distinct sets. Each bead set can be coated with a reagent specific to a particular bioassay, allowing the capture and detection of specific analytes from a sample. Within the Luminex compact analyzer, lasers excite the internal dyes that identify each microsphere particle, and also any reporter dye captured during the assay. Many readings are made on each bead set, further validating the results. xMAP technology allows rapid and precise multiplexing of up to 100 unique analytes within a single DNA or serum sample.