GENEXPERT SYSTEM

• GENEXPERT® SYSTEM

  • It is the only system that combines on-board sample preparation with real-time PCR amplification and detection of targeted nucleic acid sequences. 
  • Like NAAT, but without the rudimentaries of sample preparation. 
  • Closed system limited hands-on time with the sample. The sample is just put inside the cartridge and the machine everything on its own.
  • Initially accepted by WHO for Tuberculosis detection. (AND COVID)
• GENEXPERT® SYSTEM

  • it is expensive to maintain
  • only needing a biosafety cabinet.
  • can be operated by only one person
• • system requires the use of a single disposable GeneXpert cartridge that holds the PCR reagents and hosts the PCR process.
• • cartridges are self-contained, cross contamination is eliminated.
• Xpert reagents include sample processing controls and probe check controls. There are other internal checks the system must pass for proper analysis
• • final detection and interpretation of the results are measured by fluorescent signals that are interpolated in the specific targeted nucleic acid sequence. 
• Processing Chambers

  • Contain reagents, filters, and capture technologies necessary to extract, purify, and amplify target nucleic acids
• Optical Window

  • Enables real-time optical detection
• Reaction Tube

  • Thin chamber enables very rapid thermal cycling
• Valve

  • Enables fluid transfer from chamber to chamber
• Process

  • Extraction
  • The GeneXpert System fully automates sample preparation, doing all the complex steps of DNA extraction in its advanced “microfluidic” cartridge.

  The cartridges are designed to handle a variety of sample volumes, enabling them to obtain higher concentration of starting target material.
• Process

  • Amplification
  • Once the sample nucleic acid is extracted, it is moved from the sample processing chamber in the cartridge into the cartridge reaction tube where amplification and detection takes place.
  • The GeneXpert System module performs rapid heating and cooling cycles required for real-time PCR in the reaction tube of the cartridge.
• Amplification

  • The module continuously monitors the chemical reactions in each cartridge to quickly create enough copies of the sample nucleic acid for reliable measurement.
  • Each of the modules works independently and can be used to conduct different tests simultaneously.
• • Detection
  • The detection of the target gene sequence comes when the system’s multiple optics detects the presence of the fluorescent signals from the multiple target nucleic acids in the same cartridge.
  • With a special setting, continuous optical monitoring is possible, allowing the system to automatically stop the reaction as soon as the target is detected.
• Parts of GeneXpert® Cartridge and Assembly

  • The GeneXpert® cartridge is composed of five components: The foot, valve, body, reaction tube,  and top.
• How to Use GeneXpert® Cartridge

  1. Open the cap, add the sample to be tested, and snap the cap shut.
  2. Place the closed cartridge in a GeneXpert Module. 

  • All contents will remain within the cartridge throughout processing. 

  3. A plunger lowers into the central tube, and the valve rotates to the first position. 

  4. The plunger rises, drawing in the sample.
• How to Use GeneXpert® Cartridge

  • 5. The valve rotates to a new position and the plunger lowers, pushing the sample into the active area.
  • 6. The sample flows into the active area. Organisms are trapped on the filter.
  • 7. The valve rotates to draw in washed fluid, flushing the filter and is collected in the waste chamber.
  • 8. Rotating again, the liquid reagent is drawn, then pushed through the filter.
• How to Use GeneXpert® Cartridge

  • 9. The liberated genetic material is pushed into the chamber containing reaction beads.
  • 10. To mix the solution, the plunger cycles the fluid to dissolve the beads. The sample is now prepared, and pulled into the reaction tube.
  • 11. The GeneXpert module rapidly heats and cools the reaction tube, while LEDs illuminate the solution with up to 10 colors of light.
• How to Use GeneXpert® Cartridge

  • 12. The test is now complete and the cartridge may be removed from the GeneXpert module. All contents remain contained within the cartridge for safe disposal.
• How to Use GeneXpert® Cartridge

  • A sonic horn actuates, and provides energy that breaks apart the organisms, releasing their genetic material.
  • If the solution grows brighter, color detectors confirm the presence of the targeted DNA we are looking for.
• Advantages of the GeneXpert® Cartridge

  • Fully automated
  • The total hands-on time is 2 minutes.
  • Results may be received in under an hour. 
  • Less intervention 
  • Less human error
• This is why GeneXpert is used in rural health units (RHUs) or  rural health centers because of its ease, as long as we have stable power, basic PPE, and basic training, the GeneXpert can be used.
• Sample Workflow

  1. Transfer one drop of a positive blood culture into elution reagent.
  2. Vortex and dispense sample into ‘port 5’.
  3. Dispense ‘reagent 1’ into ‘port 1’.
  4. Dispense reagent 2’ into port 2’.
  5. Insert cartridge and start assay.