PCP HIV AIDS Toolkit/Biology of HIV AIDS

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PCP HIV AIDS Toolkit Biology of HIV AIDS
This page is part of the PCP HIV AIDS Toolkit.


The Biology of HIV/AIDS[edit]

I like turtles

Purpose[edit]

The purpose of this module is to provide participants with a thorough understanding of the biology of HIV/AIDS, including what happens at the cellular level, during transmission, and the factors that affect its progression.

Rationale[edit]

Since Peace Corps Volunteers have various opportunities to be HIV/AIDS educators, they need firm grounding in the biology of the virus and how it is "and is not" transmitted. Perhaps the most important role Volunteers can play, at least in the first months of their service, is to explain or correct information about the virus. Incorrect information, or incomplete information, is a major cause of stigma and discrimination.

Target Audience[edit]

Peace Corps trainees and Volunteers

Duration[edit]

2 hours, 30 minutes

Objectives[edit]

By the end of the session, participants will be able to

  1. Describe a virus and identify the unique characteristics of HIV.
  2. Explain how HIV affects the immune system.
  3. Describe the basic life cycle of HIV.
  4. Explain the difference between HIV and AIDS.
  5. Explain the relationship between nutrition and other health factors and HIV.
  6. Explain the role of medication in treatment of HIV.

Session Outline[edit]

  1. Introduction (5 minutes)
  2. The Immune System and HIV (30 minutes)
  3. The HIV Life Cycle and AIDS (55 minutes)
  4. The Relationship Between HIV, Nutrition, and Other Health Factors (35 minutes)
  5. Antiretroviral Treatment (20 minutes)
  6. Wrap Up (5 minutes)

Facilitators/Technical Expertise[edit]

Facilitator must be knowledgeable about

  • The human immune system
  • Cell reproduction
  • The biology of HIV/AIDS

It may be helpful to have someone with medical expertise available to assist with the session.

Materials and Equipment[edit]

Preparation Checklist[edit]

  • Read the entire session and plan the session according to the time you have available.
  • Look at the elephant and lion metaphor in the Life Skills Manual [ICE No. M0063], pages 65-66, to determine if you want to use it in Part II, Step 3 (Appendix IV, pg. 26-27 in previous three-ring binder version).
  • If co-training with a person with medical expertise, review the session together and determine each co-trainer‚Äôs role for each section.
  • Prepare flip charts or other drawings.
  • Make copies of handouts. (Make one extra copy of Handout B: The Stages of HIV/AIDS Infection. Cut it apart so each stage is on a separate piece of paper for Part III, Step 3.)

Methodology[edit]

I. Introduction (5 minutes)[edit]

Step 1: Introduce the session

The purpose of this session is to provide an understanding of the biology of HIV/AIDS and how it is and is not transmitted. This information will be important to you personally, and important in any role you play in addressing the HIV/AIDS pandemic.

Some of you may already have a good understanding of this information; others may need reminding of some of the basics of cell development and human immunology. Those with science backgrounds can assist those who have not had a science class recently.

Step 2: Outline of session Reveal flip chart 1 and go over the outline of the session.

II. The Immune System and HIV (30 minutes)[edit]

Step 1: Define disease-causing agents (5 minutes)

  1. Diseases have diverse causes, which can be classified into two broad groups: infectious and noninfectious.
  2. Infectious diseases can spread from one person to another and are caused by foreign organisms or substances that invade the body. Noninfectious diseases are not communicated from person to person.
  3. Pathogens are organisms or substances that cause disease. Pathogens that infect humans include a wide variety of bacteria, viruses, fungi, protozoans and parasitic worms.
  4. Bacteria: Bacteria are microscopic single-celled organisms. Most bacteria are harmless to humans. In fact, many are beneficial and actually prevent disease. But some bacteria cause disease in humans by producing toxins, sometimes simply as a by-product of their normal metabolism, which interact negatively with the body. Examples of human diseases caused by bacteria include leprosy, strep throat, tetanus, tuberculosis and tooth decay.
  5. Virus: Viruses are not technically alive. In order to reproduce, a virus must invade a living cell and force it to make new copies. These new viruses are then released into the surrounding tissues, and seek new cells to infect. Viruses often damage or kill the cells they infect, causing disease and sometimes death. Viruses are very specific with regard to the types of cells they can enter and reproduce. For example, the flu virus infects human respiratory tract cells, and hepatitis viruses infect liver cells.

Step 2: Define HIV and the immune system (5 minutes)

  1. Use flip chart 2 to define human immunodeficiency virus - HIV (human immunodeficiency virus) is the virus that causes AIDS, Acquired Immune Deficiency Syndrome. The HIV enters and reproduces in the cells of the human immune system, and destroys these cells in the process.
    • human - it affects humans
    • immunodeficiency - it affects the immune system
    • virus - it is a virus
  2. Ask: What is the human immune system? (Allow people to respond.)
  3. Summarize with the following points:
    • The immune system:
      • Is a very complex network of organs containing cells that recognize foreign substances in the body and destroys them.
      • Filters out foreign substances, removes damaged and dead cells and acts as a security system to destroy mutant and damaged cells.
      • Is like a puzzle; many pieces come together to form a defense against pathogens. If pieces of the immune system are missing or damaged, illness can occur.

Step 3: The cells of the immune system (20 minutes) Trainer's note: Reinforce the information in this section by writing terms as you refer to them on a flip chart. Also, note where there are places to stop and have participants think about or discuss what has just been presented.

  1. Explain that you are going to give an explanation of cells and how HIV affects them. There is a lot of information, and it may be helpful to take notes.
  2. Some important facts about the approximately 100 trillion cells in your body:
    • Your body is exposed to pathogens every second of every day, in the air we breathe, the food we eat, the water we drink, even the surfaces that we touch.
    • All cells in the body have special molecules on their surface that identify them as "self," meaning that they are the body's own cells.
    • The immune system will attack anything in the body that is not carrying the "self" marker.
    • Any substance that does not carry the ‚Äúself‚Äù marker is called an antigen, and the immune system will try to destroy it. However, not all antigens are dangerous. For example, the immune system will attack a transplanted organ, because the cells from another person have different "self" markers. The immune system will treat the organ as an invader, which can lead to organ rejection. This is why recipients of transplanted organs are required to take immune suppressing drugs for life.
    • Antigens that cause disease are pathogens.
  3. The body has both red blood cells and white blood cells: red blood cells carry oxygen from the lungs to the rest of the body, and white blood cells are involved in the human immune system’s response to antigens.
  4. White blood cells are called lymphocytes and they fight infection by attacking antigens that get into the bloodstream. The body has about two trillion of these cells.
  5. There are two major types of lymphocytes: B cells and T cells.
  6. T cells are in charge of the immune system response, and circulate continuously throughout the body looking for antigens. When an antigen is found, T cells alert the immune system and instruct other cells to attack and destroy.
  7. When activated by the T cells, B cells make antibodies, which bind to and destroy specific antigens. The B cells are the worker bees of the immune system.

Stop. Ask participants to turn to a neighbor and discuss in their own words the white cells and their functions. After a few minutes, ask if anyone has questions or are unsure of what has been covered so far. Clarify as needed. Then proceed with the session.

III. The HIV Life Cycle and AIDS (55 minutes)[edit]

Step 1: HIV and T4 cells (15 minutes)

  1. Distribute "Handout A: The Life Cycle of HIV," for participants to use as you speak.
  2. Use flip chart 3 (information in Handout A) or draw as you explain the following:
    • HIV enters the body via infected bodily fluids: blood, semen, breast milk, and vaginal secretions. (More detail on transmission will be discussed in Biology Session Two).
    • Several different kinds of cells have proteins on their surface that are called CD4 receptors. HIV searches for cells that have CD4 receptors, because this is what enables the virus to bind to the cell. Although HIV infects a variety of cells, its main target is the T4-cell (also called the "T-helper cell"), which is a type of T cell that has lots of CD4 receptors. The T4-cell is responsible for warning the immune system that there are invaders (antigens) in the body.
    • Once HIV binds to a cell, it inserts HIV genetic material inside the cell's DNA. The HIV genetic material directs the cell to produce new HIV. This turns the cell into an HIV factory.
    • HIV replicates rapidly; in an HIV-infected person, billions of new virus may be produced every day.
    • HIV is highly prone to error during replication. As a consequence, many variations of HIV develop in a person. Some mutations will weaken HIV, but others will aid the virus, speeding its replication and increasing its ability to invade the immune system.
    • This high rate of mutation underlies HIV's remarkable ability to become resistant to drug therapies and to encumber the production of an HIV vaccine.
    • Once the virus reproduces, it leaves the cell to enter other cells and begins the process again, destroying the host cell in the process.
    • As HIV destroys the body's T4 cells, the body is no longer able to mount an immune response to pathogens.
    • In HIV-infected individuals, a decline in the T4 count signals the deterioration of the immune system, and thus the progressive inability of the body to combat infections.
    • As the immune system weakens, the pathogens that are normally easily handled by the body's T4 cells can now cause serious infections by taking advantage of a weaker immune system to establish themselves in the human body. They are known as opportunistic infections.

Stop. Ask participants to turn to their neighbors again, and discuss in their own words what HIV does to the immune system.

Option: You can use the elephant and lion metaphor from the Life Skills Manual here, if you want to show participants how they can make this process more visual.

Step 2: Reinforcement activity (5 minutes)

  1. Stand in a big circle.
  2. Throw a small ball to someone. The person who catches it either states something she or he learned in the session OR asks a question.
  3. Whoever answers the question gets a small prize (perhaps a red ribbon) and the ball to throw to the next person.

Step 3: Stages of infection (20 minutes)

  1. Explain:
    • The course of HIV varies considerably from person to person. Researchers are trying to identify what makes HIV and AIDS progress rapidly in one person and slowly in another.
    • In general there are four stages of disease progression. You are going to learn about one stage and share that information with others.
  2. Divide participants into four groups. Provide each group with an information sheet (created from "Handout B: The Stages of Infection for Adults," about one stage and allow 10 minutes for the group to learn the information together.
  3. Now create new groups with one person from each of the four groups. Each person shares the information they learned.
  4. Ask participants to turn to a neighbor within their group, and in their own words, explain the difference between HIV and AIDS.
  5. . Ask if they have any questions. Distribute a complete Handout B with all the stages.

Step 4: Summary (5 minutes)

  1. Spend a few minutes making sure everyone understands the basics of how the immune system works.
    • Ask: What happens when an antigen enters the body? (The response should be: The antigen enters, the T cells come into action, calling on the immune system to react. B cells are directed to produce antibodies, which attack the invading antigens, and destroy them.)
  2. Unique aspects of HIV:
    • Unlike other pathogens that enter the human body, HIV infects human immune system cells. HIV targets the T4 cells, which direct the response of the entire immune system. Without T4 cells, the immune system cannot function.
    • HIV is a retrovirus. The process it uses to replicate is highly susceptible to mutations, which enables the virus to become resistant to drug therapies and to encumber the production of an HIV vaccine.
  3. Four stages of HIV infection
    • Acute or primary infection
    • Asymptomatic HIV disease stage
    • Symptomatic HIV disease stage
    • AIDS: Advanced HIV disease stage

Step 5: Matching game (10 minutes)

  1. Explain that participants will see how well they got the information in the session so far through a game.
  2. Give directions:
    • In a minute we will form teams. Each team will receive a stack of cards with terminology and a stack of cards with definitions/characteristics (developed from the template at the end of this session).
    • You will have 2-3 minutes to organize yourself, and when I call go, see how fast you can match each terminology card to its correct definition card. Raise your hand when you are done.
    • Break yourselves into teams of approximately six per team. Those with science backgrounds should divide evenly between the teams.
  3. Distribute the cards to the teams. Call "go."
  4. Allow each team to finish, noting first, second, third, and subsequent place winners.
  5. Reconvene as a large group and check the first place winner’s answers by reviewing all together.
  6. Award a small prize to the winning team (a bag of candy or other small prize).

IV. The Relationship Between HIV, Nutrition, and Other Health Factors (35 minutes)[edit]

Step 1: Introduction

  • Explain: We are going to talk about how other health factors affect a person with HIV/AIDS.

Step 2: Small group discussion (15 minutes)

  1. Explain that small groups will work with some source material to learn more about the relationship of nutrition and tuberculosis (TB) to HIV/AIDS.
  2. Break into small groups of four to five people each. For half of the groups, post flip chart 5 "Questions Relating to Nutrition and HIV/AIDS," and give each group copies of "Handout E: Nutrition and HIV/AIDS." For the rest of the groups, post flip chart 6 "Questions Relating to HIV and Tuberculosis," and give groups copies of "Handout F: Tuberculosis and HIV/AIDS." Ask each group to list their responses on flip charts. They will have 20 minutes to work.

Step 3: Summarize (20 minutes)

  1. Come back together. Ask for some of the high points of discussion by each group.
    • Information related to nutrition and HIV/AIDS that groups should bring up:
      1. What are some of the factors that might affect the progression of HIV to AIDS or to opportunistic infections once a person is HIV-positive? (Trainer's note: If these points are not brought out in the discussion, you should add them.)
        • The overall health of a person infected with HIV affects how quickly the disease progresses. Specific factors that affect overall health in HIV-infected people include:
          • Stress
          • Depression
          • Sleep
          • Nutrition
          • Smoking
          • Drinking alcohol or using drugs
          • Getting re-infected with a different strain of HIV
          • Not preventing or treating other diseases such as TB or STIs as early as possible
      2. What are two aspects of the relationship between nutrition and HIV/AIDS?
        • A healthy diet can strengthen the immune system.
        • HIV/AIDS leads to malnutrition in specific ways:
          • HIV infection can affect the body's ability to absorb nutrients from food.
          • HIV/AIDS may affect appetite.
          • HIV/AIDS may change the body's metabolism and the ability to use nutrients effectively.
      3. Why is clean drinking water so important for someone infected with HIV or suffering from AIDS?
        • Often, newcomers to an area might get sick from the water, while local people are able to drink it without becoming ill. This is because a healthy immune system will "remember" the infectious microorganism from a previous exposure. When that pathogen enters the body again, the immune system "remembers" exactly how to respond to it, and will trigger the release of the particular antibodies to quickly destroy the pathogen before it can cause illness. When a person is first exposed to a pathogen, such as a newcomer first exposed to an infectious microorganism in local water, the immune system does not yet have antibodies for that pathogen; in the time needed for the immune system to produce antibodies, the pathogen can cause illness.
        • Because their immune systems are compromised, HIV-infected people are more susceptible to getting sick from unclean water, and less able to fight the illness once they have it.
    • Information related to tuberculosis and HIV that groups should bring up:
      1. What is tuberculosis, how is it spread, and how common is it?
        • Tuberculosis (TB) is an infectious bacterial disease that usually affects the lungs, but can affect other parts of the body as well.
        • One third of the world's population is infected with the TB bacteria.
        • There are two kinds of TB:
          1. Latent TB (TB infection): People with latent TB have no symptoms and are not contagious. The immune system isolates the TB bacteria which, protected by a thick waxy coat, can lie dormant for years. When a person’s immune system is weakened, the chance of developing TB disease is greater. Latent TB infection can be treated so it does not become active TB disease.
          2. Active TB (TB disease): People with active TB appear to be sick. Common symptoms are: bad cough, chest pain, fever, weakness. Only people with active TB in their lungs are contagious and when they cough, sneeze, talk, or spit, people nearby may breathe in the TB bacteria and become infected. Five to ten percent of people with latent TB (but who are not infected with HIV) will develop active TB at some time during their life. Active TB can be treated and cured; an untreated person may infect on average 10 to 15 people per year.[1]
      2. What is the relationship between HIV and TB?
        • People who are co-infected with both HIV and latent TB have a much higher risk of developing active TB compared to people not infected with HIV.[2]
        • TB progresses faster in HIV-infected people
        • TB is the leading cause of death among people who are HIV-positive (and accounts for up to a third of AIDS deaths worldwide).[3]
        • TB is harder to diagnose in HIV-positive people.
        • TB in HIV-positive people is more likely to lead to death if left untreated.
        • Because TB is spread through the air, an increase in active TB among people co-infected with TB and HIV results in:
          • more transmission of the TB bacteria;
          • more people with latent TB; and
          • more TB disease in the whole population.
      3. What is the Directly Observed Therapy (DOT) program?
        • Directly Observed Therapy (DOT) is a strategy to help TB patients take their medicine correctly and consistently:
          • Provides six to eight months of regularly supervised treatment (including direct observation of drug-taking for at least the first two months)
          • Includes a reporting system to monitor treatment progress and program performance
        • Produces cures of up to 95 percent even in poorest countries
        • Helps to prevent development of drug-resistant strains by ensuring full course of drugs taken
      4. What is multiple drug-resistant TB?
        • Active TB disease caused by bacteria that is resistant to the most common drugs
        • Caused by inappropriate treatment, such as being given an incomplete regimen of drugs, or not taking full course of drugs
        • Requires a more expensive, complex treatment which is often more toxic for patients

Step 3: Transition

  1. Staying healthy, maintaining good nutrition, and drinking clean water are all important in fighting HIV once infected. People with HIV need to understand this information so they can take action to increase their longevity.
  2. In addition, antiretroviral therapy is extremely important in extending the lives of people with HIV/AIDS.

V. Antiretroviral Treatment (20 minutes)[edit]

Step 1: Explain (10 minutes)

  1. There is no cure for HIV or AIDS. Antiretroviral (ARV) treatment is not a cure, but it can keep HIV-positive people from becoming ill for many years. The treatment consists of drugs that have to be taken every day for the rest of someone's life.
  2. ARV treatment works by slowing down the replication of HIV in the body.
  3. Distribute "Handout C: Blocking HIV Reproduction: How ARVs Work," and reveal flip chart 4. Use the diagram to explain the points at which different HIV drugs interfere with the replication of HIV. Points to make:
    • There are different groups of ARV drugs, and each group interferes with HIV replication in a different way. For example, ARV drugs slow down the replication process:
      • by interfering with the different proteins that HIV needs to replicate
      • by preventing HIV from entering new cells
    • For ARV treatment to be effective for a long time, it is necessary to take two or more different kinds of ARV drugs at the same time. This strategy is called combination therapy, and it greatly reduces the rate at which HIV drug resistance develops. The term Highly Active Antiretroviral Therapy (HAART) is used to describe a combination of three or more ARV drugs.

Step 2: Starting ARV treatment (10 minutes)

  1. Choosing when to begin ARV treatment is a very important decision. There are different views of the benefits of starting HIV treatment earlier or later. However, most guidelines recommend not starting ARV treatment until the advanced stage of HIV infection. [4]
  2. Ask the participants to identify some of the challenges of ARV treatment.
    • Duration: Once treatment has begun it must be adhered to, despite side effects and other challenges.
    • Adherence or compliance: The simplicity of a regimen has a great effect on adherence. Factors associated with poor adherence include unstable housing, mental illness, and major life crises. Adherence to the HIV drug regimen means taking all of the prescribed anti-HIV drugs at the scheduled times and not missing any doses. Skipping only a few pills can trigger the emergence of drug resistant strains of HIV. This could create a more serious problem than the initial infection because the resistant virus could overwhelm the individual taking the drugs and anyone else to whom the virus is transmitted.
    • Cost: Many HIV-positive people cannot afford the lifelong cost of ARV drugs. However, some governments provide subsidized ARV treatment, and global HIV initiatives such as the President‚Äôs Emergency Plan for AIDS Relief (PEPFAR), and the Global Fund to fight AIDS, Tuberculosis and Malaria (The Global Fund) are increasing access to ARV drugs. (For more information, please refer to the Capacity Building Module, Session Two, and www.pepfar.gov.)
    • Side effects: Side effects from ARV treatment range from mild to serious health problems. Side effects include: anemia, nausea, headache, hair loss, loss of bone mineral density, high cholesterol levels associated with coronary artery disease, liver disease, severe gastrointestinal irritation or diabetes. Sometimes, patients will need to alter their drug regimen (under consultation with their health-care providers) because they are unable to tolerate the side effects.

VI. Wrap Up (5 minutes)[edit]

Step l: Review and application

  1. What did you learn that surprised you?
  2. How will understanding the biology of HIV help you in your work?

Step 2: Link to stigma and discrimination - Remind participants that stigma and discrimination may keep people from finding out about their HIV status, learning about and changing risky behaviors, and taking steps to live the most productive (and non-transmitting) lives they can if they test positive. Stigma and discrimination is often based on incorrect or inadequate understanding of the biology of HIV. Volunteers can address stigma and discrimination by helping people learn the facts about HIV and its transmission.

Step 3: Handouts - Provide participants with any handouts they did not get during the session.

Resources[edit]

  • Granich, Reuben, MD, MPH and Jonathan Mermin, MD, MPH, HIV Health & Your Community: A Guide for Action, The Hesperian Foundation: Berkeley, CA, 2001. (Chapter 1 - What is HIV? pps. 5-12.)
  • HIV 101: How the HIV virus reproduces and affects the human body, Powerpoint presentation: Presented by Dr. Paul Jung, Praya Baruch, and Jill Meeks, Peace Corps headquarters, 2005.
  • Life Skills Manual. Peace Corps: Washington, DC, 2001. Part III, "Facing Facts about HIV/AIDS and STDs.‚" [ICE No. M0063]
  • Stine, Gerald J., AIDS Update 2003: An Annual Overview of Acquired Immune Deficiency Syndrome, New Jersey: Prentice Hall. (Chapter 5: The Immunology of HIV Disease/AIDS, pps. 116-145.)

Evaluation[edit]

Notes[edit]

Changes to Session[edit]


  1. World Health Organization. “What is TB? How is it spread?” http://www.who.int/features/qa/08/en/index.html (accessed March 12, 2007).
  2. World Health Organization. “Joint HIV/Tuberculosis Interventions.” http://www.who.int/hiv/topics/tb/tuberculosis/en/ (accessed March 12, 2007).
  3. Stine, Gerald J, Ph.D., AIDS Update 2007: An Annual Overview of Acquired Immune Deficiency Syndrome. New Jersey: Prentice Hall, pg. 127.
  4. Stine, Gerald J, Ph.D., AIDS Update 2003: An Annual Overview of Acquired Immune Deficiency Syndrome. New Jersey: Prentice Hall.