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_[1] for the test requested, complete the Infectious Disease Requisition Form (DOH-4463)_[2] 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 118 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_[3]. Health care providers who have questions about diagnosing HIV-2 infections should contact the laboratory.