The Basics: HIV Prevention Vaccine Research

What is a vaccine?

A vaccine is a medical product designed to stimulate your body's immune system in order to prevent or control an infection. An effective preventive vaccine trains your immune system to fight off a particular microorganism so that it can't establish a serious infection or make you sick.

What is the difference between a preventive HIV vaccine and a therapeutic HIV vaccine?

Therapeutic HIV vaccines are designed to control HIV infection in people who are already HIV positive (see Therapeutic HIV Vaccines Fact Sheet). Preventive HIV vaccines are designed to protect HIV negative people from becoming infected or getting sick. This fact sheet focuses on preventive HIV vaccines.

Although there is currently no vaccine to prevent HIV, researchers are developing and testing potential HIV vaccines. The goal is to develop a vaccine that can protect people from HIV infection, or at least lessen the chance of getting HIV or AIDS should a person be exposed to the virus.

How does a preventive vaccine work?

When your body encounters a microorganism, your immune system mounts an attack on the invader. After the microorganism is defeated, your immune system continues to "remember" how to quickly beat the invader should it try to infect you again. A vaccine is designed to resemble a real microorganism. The vaccine trains your immune system to recognize and attack the real microorganism should you ever encounter it. If you've received an effective vaccine, your immune system will "remember" how to quickly attack and defeat a particular microorganism for many years.

Can an HIV vaccine give me HIV or AIDS?

The experimental HIV vaccines currently being studied in clinical trials do not contain any "real" HIV, and therefore cannot cause HIV or AIDS. However, some HIV vaccines in trials could prompt your body to produce antibodies against HIV. These HIV antibodies could cause you to test "positive" on a standard HIV test, even if you don't actually have HIV. Other tests are available that can distinguish between vaccinated and infected people. For more information about this issue, please visit http://www.hvtn.org/science/volunteerfaqs.html (click on "Will I test HIV-positive as a result of the vaccine?").

What are the different types of vaccine?

There are three main types of vaccines that are being studied for the prevention of HIV infection and AIDS:

• Subunit vaccines, also known as "component" or "protein" vaccines, contain only individual parts of HIV, rather than the whole virus. Instead of collecting these parts from the virus itself, the HIV subunits are made in the laboratory using genetic engineering techniques. These man-made subunits alone—without the rest of the virus—can prompt the body to produce an anti-HIV immune response, although that response may be too weak to actually protect against future HIV infection.

• Recombinant vector vaccines take advantage of non-HIV viruses that either don't cause disease in humans or have been deliberately weakened so that they can't cause disease. These weakened (attenuated) viruses are used as vectors, or carriers, to deliver copies of HIV genes into the cells of the body. Once inside cells, the body uses the instructions carried in the copies of HIV genes to produce HIV proteins. As with subunit vaccines, these HIV proteins can stimulate an anti-HIV immune response. Most of the recombinant vector vaccines for HIV deliver several HIV genes (but not the complete set) and may therefore create a stronger immune response. Some of the virus vectors being studied for HIV vaccines include ALVAC (a canarypox virus), MVA (a type of cowpox virus), VEE (a virus that normally infects horses), and adenovirus-5 (a human virus that doesn't usually cause serious disease) based vectors.

• DNA vaccines also introduce HIV genes into the body. Unlike recombinant vector vaccines, DNA vaccines do not rely on a virus vector. Instead, "naked" DNA containing HIV genes is injected directly into the body. Cells take up this DNA and use it to produce HIV proteins. As with subunit and recombinant vector vaccines, the HIV proteins trigger the body to produce an immune response against HIV.

Again, none of these vaccines contain real HIV or anything else that could cause HIV infection or AIDS.

What is a prime-boost vaccination strategy?

A single type of HIV vaccine may be used alone, or it may be used in combination with another type of HIV vaccine. One approach to combined HIV vaccination is called the prime-boost strategy. In this approach, administration of one type of HIV vaccine (such as a DNA vaccine) is followed by later administration of a second type of HIV vaccine (such as a recombinant vector vaccine). The goal of this approach is to stimulate different parts of the immune system and enhance the body's overall immune response to HIV.

How can I participate in a vaccine clinical trial?

Clinical trial volunteers are tremendously important in the effort to develop a preventive HIV vaccine. To find an HIV vaccine trial near you, contact AIDSinfo toll-free at 1–800–448–0440 to speak to an Information Specialist, who will help you locate trials in your area. You can also locate research sites using the AIDSinfo Vaccine Web page at http://aidsinfo.nih.gov/Vaccines/.

Enrolling in a clinical trial isn’t the only way to help the HIV vaccine effort—there are other ways to participate. Consider serving on an HIV vaccine Community Advisory Board.Get involved with outreach and community education programs. Lobby your elected officials to support HIV vaccine research and development. Or volunteer in other HIV/AIDS prevention, treatment, and support efforts—all are valuable ways to contribute.

For more information about HIV vaccines:

http://www.vrc.nih.gov/VRC/
http://www.hvtn.org/
Or contact your doctor or an AIDSinfo Health Information Specialist at 1–800–448–0440 or http://aidsinfo.nih.gov.

Terms Used in This Fact Sheet:

Antibody: a protein produced by the body's immune system that recognizes and fights infectious organisms and other foreign substances that enter the body. Each antibody is specific to a particular piece of an infectious organism or other foreign substance.

Clinical trial: a scientifically designed study testing the safety and effectiveness of a medication or other treatment in human volunteers.

Gene: a short segment of DNA or RNA that acts as a blueprint for building a specific protein.

Genetic engineering: a laboratory technique that can produce custom-made proteins for use as drugs and vaccines.

Microorganisms: small life forms that can be seen only through a microscope, including bacteria, protozoa, viruses, and fungi.

Vector: a harmless virus or bacteria used as a vaccine carrier to deliver pieces of a disease-causing organism (such as HIV) into the body's cells.

A Service of the U.S. Department of Health and Human Services. Reviewed May 2006

The Basics: Therapeutic HIV Vaccine Research

What is a vaccine?

A vaccine is a medical product designed to stimulate your body's immune system in order to prevent or control an infection. An effective vaccine trains your immune
system to fight a particular microorganism so that it can't make you sick.

Although there are currently no vaccines to prevent or treat HIV, researchers are developing and testing potential HIV vaccines. HIV vaccines designed to prevent HIV infection in HIV negative people are called preventive vaccines (see Preventive HIV Vaccines Fact Sheet). HIV vaccines designed to help control HIV infection in people who are already HIV positive are called therapeutic vaccines. This fact sheet focuses on therapeutic HIV vaccines.

What is a therapeutic HIV vaccine?

A therapeutic HIV vaccine (also known as a treatment vaccine) is a vaccine used in the treatment of an HIV infected person. Therapeutic HIV vaccines are designed to boost the body's immune response to HIV in order to better control the infection. Currently, there are no therapeutic HIV vaccines approved by the Food and Drug Administration (FDA). However, therapeutic HIV vaccines are being tested in clinical trials to find out if they are safe and effective in treating people with HIV.

Researchers hope that if therapeutic vaccines are able to strengthen the body's natural anti-HIV immune response, people with HIV will not have to rely exclusively on the antiretroviral drugs now used to treat HIV infection. Currently, antiretroviral drugs must be taken for life, and some cause serious side effects. All experimental therapeutic HIV vaccines are in very early stages of research, and no therapeutic vaccine is anticipated to be available to the general public for many years, if at all.

Will a therapeutic HIV vaccine be able to cure HIV?

Probably not. If therapeutic vaccines are effective, they may be able to help keep HIV infection under control. However, most researchers do not think therapeutic HIV vaccines will be able to completely eliminate HIV infection, because the virus hides in certain cells of the body where it can last for decades.

Will a therapeutic vaccine rule out the need for antiretroviral drugs?

Even an effective therapeutic HIV vaccine probably won't be able to replace antiretroviral drugs entirely. At best, a therapeutic HIV vaccine may help control HIV infection and keep people healthy while minimizing the need for antiretroviral drugs.

Who is eligible to receive a therapeutic vaccine?

Therapeutic vaccines are designed specifically for HIV positive people who have healthy immune systems. Therapeutic vaccine recipients must have strong immune systems for the vaccine to generate an effective anti-HIV immune response. Clinical trials of therapeutic vaccines are recruiting volunteers with CD4 counts greater than 250 cells/mm³, and most studies require a CD4 count greater than 350 cells/mm³. People with weaker immune systems may be unable to produce a good immune response to a therapeutic HIV vaccine, and are therefore not eligible for these trials. Most trials require that therapeutic vaccine recipients continue taking antiretroviral drugs during the study.

What are the side effects of therapeutic vaccines?

Because testing is ongoing, not all of the side effects of therapeutic vaccines are known. However, side effects observed so far in clinical trials have been similar to the side effects that occur with FDA-approved vaccines. These side effects include:

• Soreness, swelling, redness, or pain at the site of injection
• Mild flu-like symptoms (fever, chills, muscle pain or weakness, nausea, headache, and dizziness)

I am interested in participating in a therapeutic HIV vaccine trial. How do I find a study near me?

Contact AIDSinfo toll-free at 1–800–448–0440 to speak to a Health Information Specialist, who will help you locate therapeutic vaccine trials in your area. You
can also locate research sites using the AIDSinfo Vaccine Web page at http://aidsinfo.nih.gov/Vaccines On the left side of the screen, under "Therapeutic AIDS Vaccine Trials," click "New and Recruiting Trials" for a complete list of currently recruiting therapeutic HIV Vaccine studies.

Enrolling in a clinical trial isn’t the only way to help the therapeutic HIV vaccine effort—there are other ways to participate. Consider serving on an Institutional Review Board overseeing therapeutic HIV vaccine trials. Lobby your elected officials to support therapeutic HIV vaccine research and development. Or volunteer in other HIV/AIDS treatment and support efforts—all are valuable ways to contribute.

For more information about HIV vaccines:
Contact your doctor or an AIDSinfo Health Information Specialist at 1–800–448–0440 or http://aidsinfo.nih.gov.

Terms Used in This Fact Sheet:

Antiretroviral: a medication that interferes with replication of retroviruses. HIV is a retrovirus. CD4 Count: CD4 cells, also called T cells or CD4⁺ T cells, are white blood cells that fight infection. HIV destroys CD4 cells, making it harder for your body to fight infections. A CD4 count is the number of CD4 cells in a sample of blood.

Clinical trial: a scientifically designed study testing the safety and effectiveness of a medication or other treatment in human volunteers.

Microorganisms: small life forms that can be seen only through a microscope, including bacteria, protozoa, viruses, and fungi.

A Service of the U.S. Department of Health and Human Services.

The Basics: Starting Anti-HIV Medications

I am HIV positive. Do I need to take anti-HIV medications?

You do not necessarily need to take anti-HIV (also called antiretroviral) medications just because you are HIV positive. You and your doctor will determine the best time to start treatment. When to take anti-HIV medications depends on your overall health, the amount of virus in your blood (viral load), and how well your immune system is working.

How will I know when to start anti-HIV medications?

You should start treatment if:
• you are experiencing severe symptoms of HIV infection or have been diagnosed with AIDS
• your CD4 count is 350 cells/mm³ or less (especially if 200 cells/mm³ or less)
• you are pregnant
• you have HIV-related kidney disease
• you are being treated for hepatitis B

If anti-HIV medications can help me stay healthy, why wait to start treatment?
Once you begin treatment, you may need to continue taking anti-HIV medications for the rest of your life.

Although newer anti-HIV medications are easier to take, starting treatment usually means a significant adjustment in your lifestyle. Some anti-HIV medications need to be taken several times a day at specific times and may require a change in the foods you eat, when you eat meals, and when you take other medications.

In addition to their desired effects, anti-HIV medications may have negative side effects, some of which are serious. If the virus is not suppressed completely, drug
resistance can develop. Side effects and drug resistance may limit your future treatment options.

What treatment is right for me?

The U.S. Department of Health and Human Services (HHS) provides HIV treatment guidelines to doctors and patients. These guidelines recommend that you take a
combination of three or more medications from different classes (see Approved Medications to Treat HIV Infection Fact Sheet) in a regimen called Highly Active Antiretroviral Therapy (HAART). The guidelines list "preferred" HAART regimens. However, your regimen should be tailored to your needs. Factors to consider in selecting a treatment regimen include:

• your drug resistance testing results
• number of pills
• how often the pills must be taken
• if pills can be taken with or without food
• how the medications interact with one another
• other medications you take
• other diseases or conditions
• pregnancy

For more information:

Contact your doctor or an AIDSinfo Health Information Specialist at 1–800–448–0440 or http://aidsinfo.nih.gov.

Terms Used in This Fact Sheet:

AIDS: Acquired Immune Deficiency Syndrome. AIDS is the most severe form of HIV infection. HIV infected patients are diagnosed with AIDS when their CD4 count falls below 200 cells/mm3 or if they develop an AIDS-defining illness (an illness that is very unusual in someone who is not HIV positive).

Antiretroviral: a medication that interferes with replication of retroviruses. HIV is a retrovirus. CD4 count: CD4 cells, also called T cells or CD4⁺ T cells, are white blood cells that fight infection. HIV destroys CD4 cells, making it harder for your body to fight infections. A CD4 count is the number of CD4 cells in a sample of blood.

Drug resistance testing: A laboratory test to determine if an individual's HIV strain is resistant to any anti-HIV medications. HIV can mutate (change form), resulting in HIV that cannot be controlled with certain medications.

Viral load: the amount of HIV in a sample of blood.

A Service of the U.S. Department of Health and Human Services. This information is based on the U.S. Department of Health and Human Services' Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents (available at http://aidsinfo.nih.gov).

The Basics: Seeing an HIV Doctor

I am HIV positive. What kind of doctor do I need?

Your doctor (or other health care provider) should be experienced in treating HIV and AIDS. You may want to see an infectious disease specialist. You will need to work closely with your doctor to make informed decisions about your treatment, so it is important to find a doctor with whom you are comfortable.

What can I expect at the doctor's office?

Your doctor will ask you questions about your health, life style, conduct a physical exam, and order blood tests. This is a good time to ask your doctor questions. Write
down any questions you have and take them with you to your appointment.

Women should have a pregnancy test (see HIV During Pregnancy, Labor and Delivery, and After Birth Fact Sheet series) and a gynecologic examination with Pap smear.

What questions should I ask my doctor?

You should ask your doctor about:
• Risks and benefits of HIV treatment
• Other diseases you may be at risk for
• How your lifestyle will change with HIV infection
• How you can avoid transmitting HIV to others
• How you can achieve and maintain a healthier lifestyle

What tests will my doctor order?

It is very important to have a CD4 count and a viral load
test done at your first doctor's visit. You should also have
drug resistance testing. The results will provide a
baseline measurement for future tests.

• CD4count – CD4 cells, also called CD4+ T cells or CD4 lymphocytes, are a type of white blood cell that fights infection. HIV destroys CD4 cells, weakening your body's immune system. A CD4 count is the number of CD4 cells in a sample of blood.

• Viral load test – A viral load test measures the amount of HIV in a sample of blood. This test shows how well your immune system is controlling the virus. The two viral load tests commonly used for HIV are:
    • HIV RNA amplification (RT-PCR) test
    • Branched chain DNA (bDNA) test

• Drug resistance testing – Drug resistance testing determines if an individual's HIV strain is resistant to any anti-HIV medications. HIV can mutate (change form), resulting in HIV that cannot be controlled with certain medications.

To ensure accurate results, viral load testing should be done at two different times, by the same laboratory, using the same type of test. The results of different types of tests may differ.

Your doctor may also order:
• Complete blood count
• Bloodchemistryprofile(including liver and kidney function tests)
• Tests for other sexually transmitted diseases (STDs)
• Tests for other infections, such as hepatitis, tuberculosis, or toxoplasmosis

Am I ready to begin HIV treatment?

Once you begin taking anti-HIV medications, you may need to continue taking them for the rest of your life. Deciding when or if to begin treatment depends on your health (see Starting Anti-HIV Medications Fact Sheet) and your readiness to follow a treatment regimen that may be complicated. You and your doctor should discuss your readiness to begin treatment as well as strategies to help you follow your treatment regimen (see What is Treatment Adherence and Adhering to a Regimen Fact Sheets).

If my doctor and I decide to delay treatment, will I need to have my CD4 count and viral load tested again?

Yes. HIV infected people who have not started anti-HIV medications should have a viral load test every 3 to 4 months and a CD4 count every 3 to 6 months. You and your doctor will use the test results to monitor your infection and to decide when to start treatment.

For more information:

Contact your doctor or an AIDSinfo Health Information Specialist at 1–800–448–0440 or http://aidsinfo.nih.gov.

Terms Used in This Fact Sheet:

Baseline: an initial measurement (such as CD4 count or viral load) made before starting therapy and used as a reference point to monitor your HIV infection.

Kidney function tests: blood and urine tests that determine if your kidneys are working properly.

Liver function tests (LFTs): tests that measure the blood levels of liver enzymes (proteins made and used by the liver) to determine if your liver is working properly.

A Service of the U.S. Department of Health and Human Services. This information is based on the U.S. Department of Health and Human Services' Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents (available at http://aidsinfo.nih.gov).