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HIV-2 Nucleic Acid Testing

The Bloodborne Viruses Laboratory (BVL) provides HIV-2 nucleic acid testing to diagnose and monitor HIV-2 infections. This testing is provided for all New York State submitters who have a patient who is known or suspected to be infected with HIV-2. Contact the laboratory for more information and to request approval to submit specimens. After receiving approval to submit specimens, follow the collection and shipping guidelines for the test requested, complete the DOH-49 test requisition form in full, and choose either HIV-2 viral load testing or HIV-2 qualitative RNA testing from the HIV testing menu. HIV-2 viral load testing is performed 1-2 times a month. HIV-2 qualitative RNA testing is performed on an as-needed basis.   

Description of Tests

HIV-2 Real-Time PCR Assays for RNA detection (Qualitative RNA) and Quantification (Viral Load): The HIV-2 Real-Time PCR assays were developed and validated by the Bloodborne Viruses Laboratory to detect and quantify HIV-2 RNA isolated from human plasma.  Assay steps include viral RNA extraction, reverse transcription, and detection by real-time PCR.  The assays detect a conserved region of the HIV-2 LTR repeat region.  HIV-2 standards are included to produce quantitative results that are reported in HIV-2 RNA international units (IU) /ml.  These assays were approved by the NYSDOH Clinical Laboratory Evaluation Program for diagnosing and monitoring HIV-2 infection.  For plasma specimens, the assays have a limit of detection of 7 IU/ml and a lower limit of quantification of 56 IU/ml. 

HIV-2 Background

Human immunodeficiency virus, type 2 (HIV-2) is an uncommon form of HIV found primarily in West Africa.  Several hundred cases of HIV-2 have been diagnosed in the U.S., primarily in New York City and surrounding areas.  Although HIV-1 and HIV-2 are transmitted in similar ways and can both lead to AIDS, they differ in important ways. 

  • HIV-2 infection causes lower levels of circulating virus compared to HIV-1.  Lower HIV-2 virus levels lead to decreased transmission rates and slower progression to clinical disease. 
  • HIV-1 and HIV-2 were introduced into human populations in completely separate transmission events and are genetically very different.  Although antibodies to these viruses can cross-react because of similar viral protein structure, tests that detect HIV-1 nucleic acid (RNA or DNA) will not also detect HIV-2 nucleic acids. 
  • HIV-2 is naturally resistant to some antiretroviral drugs used to treat HIV-1.  Therefore, it is critical to correctly diagnose HIV-2 infection for optimal treatment effectiveness.

HIV-2 is usually diagnosed by detecting HIV-2 specific antibodies with specialized tests known as HIV-1/HIV-2 differentiation immunoassays.  HIV-2 infection can also be diagnosed by detecting HIV-2 nucleic acid (RNA or DNA).   However, because of the lower levels of HIV-2 virus in the blood, the absence of HIV-2 RNA does not exclude HIV-2 infection.  Patients infected with HIV-2 should be monitored with a HIV-2 viral load assay to follow disease progression and monitor treatment effectiveness.  See the NYSDOH Clinical Guidelines for additional information about HIV-2 infection. Health care providers who have questions about diagnosing HIV-2 infections should contact the laboratory.