HIV is a Retrovirus

HIV is a retrovirus that carries its genetic information in RNA rather than DNA. 1, 2

Basic HIV Biology

HIV is an RNA virus approximately 100 nm in diameter that attaches to CD4 receptors on host cells, enters the cell, and uses reverse transcriptase enzyme to make DNA from its RNA 2
As a retrovirus, HIV's genetic material is stored as RNA, which distinguishes it from many other viruses that use DNA 1
HIV primarily infects CD4+ T lymphocytes and monocyte-macrophage cells, with T cell destruction leading to immunodeficiency 2
HIV replication in CD4+ T cells results in their destruction, causing progressive loss of cellular immune function and increased susceptibility to opportunistic infections and malignancies 2

There are two main types of HIV: HIV-1 (most prevalent globally with over 30 million people infected) and HIV-2 3
HIV is transmitted through body fluids and secretions 1
After infection, HIV can lead to an immune-deficient state over approximately 2-10 years if left untreated 1
HIV-2 is naturally resistant to some antiretrovirals frequently used to treat HIV-1 infection 3

Antibody to HIV appears in blood a few weeks after infection but disappears as antibody begins to be present 2
HIV testing commonly uses ELISA and Western blot assays, with newer latex and other methods being licensed for certain circumstances 2
Routine HIV testing is recommended for sexually active adults, pregnant women, and in some cases, newborns 4

As of recent data, approximately 37 million individuals are living with HIV infection worldwide 5
In the United States, young people aged 13-24 years represented 17% of the population but accounted for an estimated 26% of all new HIV infections 4
Black youth accounted for an estimated 57% of all new HIV infections in youth in the United States, followed by Hispanic/Latino (20%) and white (20%) youth 4
More than 60% of HIV-infected youth in the United States do not know they are infected 4

Antiretroviral drugs effectively inhibit HIV replication, and combination antiretroviral therapy leads to durable suppression of viral replication 5
Viral suppression enables immune recovery and nearly eliminates the risk of developing AIDS 5
When used optimally, antiretroviral drugs can virtually eliminate the risk of HIV transmission 5
Despite effective treatment, HIV-infected individuals have a higher than expected risk of heart, bone, liver, kidney, and neurological disease 5

Looking at the options provided:

A. HIV has five identified strains - This is incorrect
B. HIV is a retrovirus - This is correct
C. HIV carries genetic information in its DNA - This is incorrect; HIV carries genetic information in RNA
D. HIV only infects T-helper (Th) cells - This is incorrect; HIV also infects monocyte-macrophage cells

Therefore, option B is the correct answer.