VIRAL LOAD TEST.

Medical Laboratory ScientistNancy Somi

Viral load is the concentration of virus in the blood stream.

Its used in conjunction with other tests to monitor the progress of patients.

WHAT IT IS..

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.

Importance of viral load test…

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.

Viral load technologies

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.

Types of viral load technologies

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)

Nucleic acid testing technologies

RT‐PCR is a method of PCR using a Reverse Transcriptase (RT) enzyme to convert viral RN

A into  complementary DNA (cDNA). The cDNA undergoes replication and detectio

n. RT‐PCR is used to  quantify HIV RNA and to 

dertemine viral load.

RT-PCR Technology

Amplicor HIV-1 monitor v1.5(Roche) Cobas Taqman (Roche) Real time HIV -1 (Abbot) VERSANT HIV-1 RNA ASSAY (kPCR)

Commercially available RT-PCR

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.

Cobas TaqMan and Ampliprep 48

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.

VIRAL LOAD TESTS TODAY

“Science grows like a weed every year”.Kary Mullis

THANK YOU!!!!!