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Viral load test

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Viral load testing techniques

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Viral load test

  1. 1. Medical Laboratory Scientist Nancy Somi
  2. 2.  Viral load is the concentration of virus in the blood stream.  Its used in conjunction with other tests to monitor the progress of patients.
  3. 3.  Its used as a primary indicator of therapeutic efficacy.  Used to monitor a change in ARV drugs in drug resistance cases  It’s a baseline indicator of disease progression.
  4. 4. Due to advanced technology viral load assays are dramatically changing to fit the current setting of developed and developing countries. These assays differ in.  Sensitivity  Dynamic range  Target region  Extraction, amplification and detection in nucleic acid based assays.
  5. 5.  Nucleic Acid Testing Technologies (NAT)-They detect and quantify Viral RNA  Non-Nucleic Testing Technologies( NNAT) They are based on the detection and quantification of HIV viral enzymes and proteins which can be used as a correlate measure of viral RNA.
  6. 6. Three major methods for detecting and quantifying nucleic acids.  Reverse transcription polymerase chain reaction.(RT-PCR)  Nucleic Acid Sequence Based Amplification(NASBA)  Branched chain DNA (bDNA)
  7. 7.  RT‐PCR is a method of PCR using a Reverse Transcriptase (RT) enzyme to convert viral RNA into complementary DNA (cDNA). The cDNA undergoes replication and detection . RT‐PCR is used to quantify HIV RNA and to dertemine viral load.
  8. 8.  Amplicor HIV-1 monitor v1.5(Roche)  Cobas Taqman (Roche)  Real time HIV -1 (Abbot)  VERSANT HIV-1 RNA ASSAY (kPCR)
  9. 9.  The COBAS Taqman is a real time PCR that targets both the gag and LTR regions of the HIV genome.  Coupled with the COBAS Ampliprep, viral load quantification is a fully automated process.  It can detect as low as 20cp/ml.
  10. 10.  Can only be accessed by developed countries and a very few places in developing countries.  In developed countries it’s the most baseline investigation in HIV positive patients.
  11. 11. “Science grows like a weed every year”. Kary Mullis THANK YOU!!!!!

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