HIV confirmation testing available at NRL

Published on : 24 July 2017
Location : Abu Dhabi

As part of our continuous efforts to expand our in-house test menu, we have recently added two HIV1/2 confirmatory testing, performed at our ICAD laboratory.  Please find more information below:

Order Code

Order Code Name

CPT Code

Specimen type

Volume

Specimen container

Storage

Specimen stability

TAT*days

083904

 HIV-1/2 Ab Confirmation and Differentiation,

Serum

86701

86702

Serum

5 ml

Gel barrier tube

Refrigerate

7 days at 2°C to 8°C

1-2 days

139350

Human Immunodeficiency Virus-1 Qualitative RNA, Plasma

87535

Plasma

3 ml;

Minimum volume: 1.5 ml

2 x Lavender-top (EDTA) tube

Store whole blood at 2-25°C for no longer than 24 hours. Separate plasma from whole blood within 24 hours of collection by centrifugation at 800-1600 x g for 20 minutes at room temperature. Transfer plasma to a sterile polypropylene tube.

6 weeks if frozen at

-20°C to

-80°C.

3-5 days

 

Clinical significance:

Human Immunodeficiency Virus (HIV) is the etiologic agent of Acquired Immunodeficiency Syndrome (AIDS)1-3. HIV infection can be transmitted by sexual contact, exposure to infected blood or blood products, or by an infected mother to the fetus. Within three to six weeks of exposure to HIV, infected individuals generally develop a brief, acute syndrome characterized by flu-like symptoms and associated with high levels of viremia. In most infected individuals this is followed by an HIV-specific immune response and a decline of plasma viremia , usually within four to six weeks of the onset of symptoms. After seroconversion, infected individuals typically enter a clinically stable, asymptomatic phase that can last for years. The asymptomatic period is characterized by persistent, low level plasma viremia and a gradual depletion of CD4+ T lymphocytes, leading to severe immunodeficiency, multiple opportunistic infections, malignancies and death15. Although virus levels in the peripheral blood are relatively low during the asymptomatic phase of the infection, virus replication and clearance appear to be dynamic processes in which high rates of virus production and infection of CD4+ cells are balanced by equally high rates of virus clearance, death of infected cells and replenishment of CD4+ cells, resulting in relatively stable levels of both plasma viremia and CD4+ cells16-18.

Acquired immunodeficiency syndrome (AIDS) is caused by viruses transmitted by sexual contact, exposure to blood (including sharing contaminated needles and syringes) or certain blood products, or transmitted from an infected mother to her fetus or child during the perinatal period.  Additionally, transmission of these viruses can occur through tissue transplantation.  Human Immunodeficiency Virus Type 1 (HIV-1) has been isolated from patients with AIDS and AIDS-related complex (ARC).  HIV-1 was thought to be the sole causative agent of these syndromes until 1986, when a second type of Human Immunodeficiency Virus (HIV-2) was isolated and also reported to cause AIDS.  Since the initial discovery, hundreds of cases of HIV-2 infection have been documented worldwide, including cases of AIDS related to HIV-2.  In the United States, there have been more than 80 cases of infection with HIV-2 reported, including three potential blood donors.

This second immunodeficiency virus is similar to, but distinct from, HIV-1. Both viruses have similar morphology and lymphotropism, and the modes of transmission appear to be identical.  The HIV-1 and HIV-2 genomes exhibit about 60% homology in conserved genes such as gag and pol, and 39-45% homology in the envelope genes.  Serologic studies have also shown that the core proteins of HIV-1 and HIV-2 display frequent cross-reactivity whereas the envelope proteins are more type-specific.

Within the two major HIV types, there is significant variation, as well. By analyzing sequences of representative strains, HIV-1 has been divided into four groups: group M (for major), including at least 9 subtypes, 3 sub-subtypes of A, and 2 sub-subtypes of F (A1, A2, A3, B, C, D, F1, F2, G, H, J, and K); group O (for outlier); group N (for non-M, non-O), and group P.  Similarly, the HIV-2 strains have been classified into at least five subtypes (A through E).  Some HIV-1 variants share ≤50% homology in their envelope genes with the sequences of more common prototype strains.

Despite some degree of immunological cross-reactivity between types and subtypes of HIV, reliable detection of the more divergent strains may only be achieved by incorporating specific sequences into the assay design.  In one study, detection of HIV-2 positive samples by licensed HIV-1 antibody kits ranged from 60% to 91%, depending on the test used.  Detection of HIV-1 Group O samples by HIV-1 and HIV-1/HIV-2 assays varied from 0% to 100% in studies with U.S.- licensed and European test kits.

139350 - Human Immunodeficiency Virus-1 Qualitative RNA, Plasma

A nucleic acid amplification tests can diagnose an HIV infection during the first 18 months of life while the infant’s blood still contains maternal antibodies that complicate the interpretation of serologic tests. Detection of HIV-1 in plasma may provide evidence for current infection, using nucleic acid amplification technologies, such as the Polymerase Chain Reaction (PCR)27-29. The Human Immunodeficiency Virus-1 Qualitative RNA uses PCR technology to achieve maximum sensitivity for the qualitative detection of HIV-1 in EDTA anti-coagulated plasma and dried blood spots from whole blood.

083904 - HIV-1/2 Ab Confirmation and Differentiation,  Serum

HIV-1/2 Ab Confirmation and Differentiation test is intended for use as an additional, more specific test to confirm the presence of antibodies to HIV-1 and HIV-2, for specimens found to be repeatedly reactive by diagnostic screening procedures.  This assay can be used in accordance with current CDC recommendations for Laboratory Testing for the Diagnosis of HIV Infection.  Per the CDC recommended algorithm, specimens initially reactive on a 4th generation HIV assay should undergo supplemental testing with an immunoassay that differentiates HIV-1 from HIV-2 antibodies.