Early Detection of HIV

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson, we'll be learning about techniques for early detection of HIV. First, we'll review what HIV is and its route of infection. Then, we'll learn about four types of early detection tests.

What Is HIV?

Picture a war. The battle has been going on for years. Enemy troops are sneaking inside our lines, bringing in new soldiers. They've taken over our buildings and are manufacturing their own weapons. Their only goal is to multiply and take control of our resources. But, the more resources they take, the harder it is to strike back.

This bleak scene of war might stir up black and white movies of World War II, but it also describes a microscopic battle raging on inside our body. Human immunodeficiency virus (HIV) is the invader, and our bodies are the cities. HIV enters the body through blood, breast milk, or sexual fluids and attacks our immune cells. So, not only is the virus making us sick, but it also destroys our defenses, leaving us susceptible to other infections.

HIV shown in green buds from an immune cell during infection

Although HIV is incurable, many strides have been made in controlling the disease. One important part of that is having patients get tested regularly, and right away if they think they have been exposed. Early testing allows treatment to begin quickly, which lets doctors fight the virus before it causes too much damage. Today, we're going to learn about the types of early detection tests available.

Types of HIV Early Detection Tests

HIV is sneaky. It can lie dormant in the body, and patients can go on without symptoms for up to ten years, in which time they might unknowingly pass the virus onto other people. People might feel sick when first infected, but symptoms are similar to the flu.

Acute HIV symptoms
acute HIV symptoms

To control disease outbreak, everyone who is sexually active should get tested yearly, or every time they switch partners. However, if you think you have been in contact with HIV, through blood or sexual fluids of an infected person, it's time for a test so you can get results right away.

Antibody Test

Everyone's body makes a protein called an antibody when they are sick. These proteins are made by immune cells and specifically attach to a pathogen, letting the immune cells know to kill it. If you have HIV, your body makes these antibodies to match HIV. The antibody test detects these antibodies. However, most people only make enough antibodies for detection between four to six weeks after infection, and about 98% will make enough at twelve weeks post infection.

RNA Test

RNA is the genetic material of HIV. It contains the information the virus needs to replicate inside the host cells. Think of it like blueprints for virus particles. The RNA test directly detects this viral RNA. Our cells have RNA too, but it looks different from the viral RNA, so the test only detects RNA from HIV. Since it detects the virus directly, this test can find HIV about nine to fourteen days after infection, making it the earliest test available.


HIV is a sneaky virus. After it gets into your cells, it turns its RNA genome into a different form called DNA, which is the same material as our genome. Then, the virus inserts its DNA into your genome, forcing your cells to continuously make virus particles unknowingly. The cell just sees its own DNA, and doesn't realize it is replicating virus particles.

A test, called polymerase chain reaction, or PCR can detect this process two to three weeks post infection. The test requires a sample of blood from the patient. The scientists then add small molecules called primers, enzymes, and buffers, which can detect and amplify the viral DNA in the test tube. This allows the scientists to see how much viral DNA is in your cells.

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