Yes, HIV (Human Immunodeficiency Virus) is a viral infection. Specifically, it belongs to a family of viruses called retroviruses, which store their genetic information as RNA and convert it into DNA once inside a human cell. This distinction matters because it explains both how HIV behaves differently from many other infections and why it requires a specific type of treatment to control.
What Type of Virus HIV Is
HIV is classified as a lentivirus, a subgroup of retroviruses known for causing slow, progressive disease. Unlike a cold virus that triggers symptoms quickly and is cleared by the immune system within days, HIV inserts itself into your DNA and persists indefinitely. This is the core reason HIV cannot be cured with current medicine: once the virus writes itself into your cells, those cells carry the viral blueprint for life.
The virus itself is remarkably small. It has a cone-shaped inner core that holds two strands of RNA along with enzymes the virus needs to hijack human cells. Surrounding this core is a lipid envelope studded with proteins that latch onto specific immune cells.
How HIV Infects the Body
HIV targets a specific type of immune cell called a CD4 cell (sometimes called a T-helper cell). These cells coordinate much of the immune response, which is why losing them has such devastating consequences. The infection unfolds in seven stages, each exploiting a different vulnerability.
First, proteins on the virus’s surface bind to receptors on the CD4 cell, then the viral envelope fuses with the cell membrane, allowing HIV to slip inside. Once in, the virus uses a special enzyme to convert its RNA into DNA, a process called reverse transcription. That newly made viral DNA then travels into the cell’s nucleus and integrates directly into the cell’s own DNA. From that point, the infected cell becomes a factory: it reads the viral instructions embedded in its DNA, produces new viral proteins, assembles immature virus particles, and releases them to infect more CD4 cells.
Each of these steps is a potential target for treatment, which is why modern HIV medications are so effective. Different drug classes block different stages, from entry and reverse transcription to integration and final assembly.
Three Stages of HIV Infection
Without treatment, HIV infection progresses through three distinct stages.
Acute infection occurs in the first few weeks. The virus replicates rapidly, and many people experience flu-like symptoms: fever, sore throat, swollen lymph nodes, rash. During this phase, the amount of virus in the blood is extremely high, making the person very contagious, often before they realize they’ve been infected.
Chronic infection (also called clinical latency) can last a decade or longer. The virus is still active and reproducing, but at lower levels. Many people feel perfectly healthy during this stage and have no symptoms at all. They can still transmit the virus, though. Without treatment, the immune system gradually weakens as CD4 cells are destroyed faster than the body can replace them.
AIDS is the final stage, diagnosed when a person’s CD4 count drops below 200 cells per milliliter of blood (a healthy count is typically 500 to 1,500). At this point, the immune system is severely compromised. Infections that a healthy immune system would easily control become life-threatening. A type of pneumonia called PCP typically emerges when CD4 counts fall below 200. Other serious infections appear at even lower counts: certain fungal infections below 150, and a bacterial infection called MAC disease below 50. Without treatment, people with AIDS typically survive about three years.
How HIV Is Detected
Because HIV is a virus, testing looks for either the virus itself or the immune system’s response to it. The fastest option is a nucleic acid test (NAT), which searches for the virus’s genetic material directly and can detect infection as early as 10 to 33 days after exposure. Antigen/antibody tests drawn from a vein detect both a viral protein and the antibodies your body produces against it, with a window of 18 to 45 days. Rapid finger-stick versions of this test take longer to become reliable, typically 18 to 90 days.
These window periods matter. A negative test taken too soon after a potential exposure may not be accurate, so retesting after the appropriate window is important.
How Treatment Works
Because HIV is a retrovirus with a well-understood life cycle, scientists have developed medications that interrupt the virus at multiple points. Modern treatment, called antiretroviral therapy, typically combines drugs from different classes to attack the virus simultaneously. Some block the virus from entering cells. Others prevent it from converting its RNA to DNA or from integrating into the cell’s genome. Newer medications even disrupt the virus’s protective shell during transport within the cell.
The goal of treatment is to reduce the amount of virus in the blood to undetectable levels. This is where one of the most important breakthroughs in HIV science comes in. People who achieve and maintain an undetectable viral load through consistent treatment cannot sexually transmit the virus to others. This principle, known as U=U (Undetectable equals Untransmittable), is backed by studies tracking thousands of couples over years, including both heterosexual and male-male partnerships. Not a single transmission was observed when the partner with HIV maintained viral suppression.
People who take treatment as prescribed may never progress to AIDS and can expect a near-normal lifespan.
Prevention Beyond Treatment
For people who don’t have HIV, a preventive medication called PrEP (pre-exposure prophylaxis) reduces the risk of getting HIV from sex by about 99% when taken as prescribed. For people who inject drugs, PrEP pills reduce risk by at least 74%. These medications work by keeping enough drug in the body to block the virus’s reverse transcription step before it can establish a permanent infection.
Roughly 40.8 million people worldwide were living with HIV at the end of 2024, and about 1.3 million acquired the virus that year. While those numbers remain significant, the combination of effective treatment, the U=U reality, and highly effective prevention tools means HIV, though still a serious viral infection, is now a manageable chronic condition for those with access to care.