HIV-1-RNA Detection (Qualitative)

What are the tests available for the detection of HIV-1 RNA in clinical specimens?

Human immunodeficiency virus (HIV)-1 infection can be usually confirmed by the detection of HIV-1-specific antibodies in serum. However, serologic testing may not reliably diagnose HIV-1 infection in newborns with passively acquired maternal HIV-1 antibodies or with incompletely developed immune systems, individuals with early HIV-1 infection (<30 days from infection), or individuals with "indeterminate" HIV-1 antibody results by supplemental serologic assays. In these circumstances, detection of HIV-1 nucleic acids (RNA or proviral DNA) by PCR can provide definitive, early evidence of HIV-1 infection (approximately 10 to 14 days after infection), during which the results of routine diagnostic assays may be inconclusive.
 
On entry into human cells (including peripheral blood mononuclear cells), the HIV-1 RNA gets converted into complementary DNA (cDNA) by reverse transcription. These linear cDNA strands then get integrated into the host cell genome, thus representing the proviral form of HIV-1. mRNA, transcribed from the proviral DNA, is used to synthesize the proteins which are required to make new viral particles. These proteins and viral RNA are packaged in the host cell cytoplasm and eventually released from the cell, thereby completing the life cycle of the virus.
 
For infants who are born to HIV-1-infected mothers, HIV-1 DNA or RNA tests are recommended at 0 to 2 days, 14 days, 1 to 2 months, and 4 to 6 months after birth. Two consecutive positive HIV-1 virologic test results (HIV-1 DNA and/or RNA) are required for confirming the diagnosis of HIV-1 infection in children younger than 2 years of age.

What are the drawbacks of the test?

This assay is useful for the detection of HIV-1 groups M (subtypes A to H), N, and O, but it may not detect all the strains of HIV-1 group N or O.
 
Diagnosis of HIV-1 infection must not rely completely upon a "Detected" result for HIV-1 DNA and/or RNA. Such a result should be considered in along with the patient's clinical presentation, physical findings, and other diagnostic laboratory tests before establishing the diagnosis. An "Undetected" result signifies only the absence of HIV-1 DNA and RNA in the sample tested and does not rule out the diagnosis of HIV-1 infection. "Undetected" results should be interpreted with care, considering the patient's risk factors for HIV-1 infection, the analytical sensitivity of the test method, and the group of the infecting strain of HIV-1. Follow-up testing is highly recommended for high-risk patients with initially "Undetected" test results. Patients on prophylactic or therapeutic antiretroviral therapy may have "Undetected" results.
 
"Undetected" results along with repeatedly positive HIV-1 antibody supplemental test results can be observed in HIV-2-infected individuals. For such patients with risk factors for HIV-2 infection, specific testing for HIV-2 antibodies (serologic) and HIV-2 DNA and/or RNA is recommended.

What is the Method description for the test?

There is The Abbott mSample Preparation System kit which is used with the automated Abbott m2000sp sample preparation system in order to extract and purify viral nucleic acids from human plasma samples, based on magnetic-particle technology. An internal control (IC) is used in the nucleic acid extraction and purification procedure for processing the test controls and clinical samples. After the capture of nucleic acids on magnetic microparticles, the microparticles are then washed to remove any unbound sample components that may be present. , the bound nucleic acids are then eluted from the microparticles and the eluates are transferred to a 96-well microtiter plate containing PCR master mix reagents for amplification and detection.
 
During the amplification process on the Abbott m2000rt system, target DNA undergoes amplification by the DNA polymerase activity of the thermostable rTth DNA polymerase. The target RNA which is present is first converted to cDNA by the reverse transcriptase activity of the enzyme and then subsequently amplified. Amplification of HIV-1 and IC targets takes occurs simultaneously in the same reaction. The target sequence for this assay is present in the pol integrase region of the HIV-1 genome and it is highly conserved. The IC sequence is obtained from the hydroxypyruvate reductase gene of the pumpkin plant, Cucurbita pepo, and is delivered in an Armored RNA particle which has been diluted in negative human plasma.
 
During the read cycles of amplification on the Abbott m2000rt, the temperature is lowered in order to allow the fluorescent detection of amplification products as the HIV-1 and IC probes anneal to their respective targets (real-time fluorescent detection). The HIV-1 probe has a fluorescent moiety that is covalently linked to the 5' end. A short quencher oligonucleotide is complementary to the 5' end of the HIV-1 probe and has a quencher moiety present at its 3' end. In the absence of HIV-1 target, the HIV-1 probe fluorescence is quenched by hybridization to the quencher oligonucleotide. In the presence of the HIV-1 target sequence, the HIV-1 probe preferentially hybridizes to the target sequence, dissociating from the quencher oligonucleotide, thereby allowing fluorescent detection. The IC probe which is used is a single-stranded DNA oligonucleotide that has a fluorophore at the 5' end and a quencher at the 3' end. In the absence of IC sequences, the IC probe obtains a series of random conformations, some of which bring the quencher close enough to the excited fluorophore to absorb its energy before it can be fluorescently emitted. When the IC probe binds to its complementary sequence in the target, the fluorophore and the quencher are held away, which allows the fluorescent emission and detection by the Abbott m2000rt. The HIV-1 and IC-specific probes are each labeled but with a different fluorophore, which allows the simultaneous detection of both amplified products.

What is HIV RNA qualitative test?

It determines whether HIV RNA is detected or undetected in the sample.

What does HIV 1 RNA not detected mean?

HIV1RNA is not detected  or HIV is not seen in the sample

When can HIV RNA be detected?

By PCR it can be detected in 10 days.

What is HIV RNA test?

It detects the number of copies of HIV RNA per ml of the sample.