Human Immunodeficiency Virus Type 2

Guideline and Commentary

John G. Bartlett, MD


June 06, 2012

In This Article

Human Immunodeficiency Virus Type 2

Editor's Note:
This guideline was prepared and published by the New York State Department of Health AIDS Institute HIV Clinical Guidelines Program. It has been republished here. Please note that recommendations are assigned an evidence-based rating and use the rating scheme developed by the Department of Health and Human Services.

HIV-2 Guideline Highlights
This guideline includes the following:
  • Recommendations for HIV-1/HIV-2 combination screening, HIV-1/HIV-2 type-differentiation testing, and HIV-2 diagnosis

  • An alternative HIV diagnostic algorithm involving HIV-1/HIV-2 type-differentiation and nucleic acid testing protocols (Figure 1)

  • Criteria for patients for whom HIV-1/HIV-2 type-differentiation and nucleic acid testing protocols are recommended during initial HIV screening (Table 1)

  • Recommendations and information about HIV-2 disease monitoring

  • Recommendations for prescribing antiretroviral therapy for HIV-2 mono-infected and HIV-1/HIV-2 co-infected patients (Table 2)

  • Recommendations for managing HIV-2-infected pregnant women and HIV-2-exposed infants


HIV-2 was first described in 1985[1] and was isolated in 1986 in West Africa,[2] where it is currently endemic. The Centers for Disease Control and Prevention (CDC) reported that, from 1988 to June 2010, 166 cases had met the CDC case definition of HIV-2 infection in the United States.[3] The largest number of cases were from the Northeast, including 77 from New York City.[3] The majority of cases had a West African origin or connection.[3] However, a report from New York City suggests that HIV-2 may be underreported because antibody cross-reactivity between HIV-1 and HIV-2 is common and frequently results in misdiagnosis of HIV-2 as HIV-1 or dual infection.[4] Incorporating a type-differentiating immunoassay into the HIV screening protocol can assist in identifying the type.[4]

HIV-2 is associated with lower viral load levels and slower rates of CD4 decline and clinical progression compared with HIV-1[5,6]; 86% to 95% of people infected with HIV-2 are long-term nonprogressors.[7,8] Recent data show that survival of persons with undetectable HIV-2 viral load is similar to that of the general population.[8] However, HIV-2 can cause immunosuppression, as well as AIDS characterized by the same signs, symptoms, and opportunistic infections that are seen in HIV-1. HIV-2-associated AIDS may often be associated with lower viral load levels than HIV-1 (>10,000 copies/mL in HIV-2 versus sometimes millions of copies/mL in HIV-1).[8]

In contrast to the detailed knowledge base for the management of HIV-1, no clinical trials have been conducted to date to guide decision-making in the management of HIV-2-related immunosuppression and progression of disease. Studies of virologic and immunologic responses to antiretroviral therapy (ART) have demonstrated a higher CD4 cell increase in HIV-1-infected patients compared with HIV-2-infected patients after initiation of therapy.[9,10,11] These factors, combined with the absence of controlled trials of ART for HIV-2, contribute to the challenge of optimal treatment of HIV-2.

Key Points
  • HIV-2-infected individuals with progressive disease are less likely to respond as predictably to ART as patients with HIV-1 infection.

  • The choice of ART for HIV-2 differs from that for HIV-1, underscoring the importance of differentiating between HIV-1 and HIV-2 in patients at risk for HIV-2 infection.

  • Clinical monitoring of HIV-2 is hampered by the absence of assays with Food and Drug Administration (FDA) approval for quantification of HIV-2 viral load, as well as a lack of consensus on interpretation of HIV-2 resistance testing.


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