HIV

Question 1

The human immunodeficiency virus (HIV) leads to the development of acquired immunodeficiency syndrome (AIDS). Eventually, people with AIDS die because they are unable to produce an immune response to pathogens.Scientists are trying to develop an effective vaccine to protect people against HIV. There are three main problems. 1. HIV rapidly enters host cells. 2. HIV causes the death of T cells that activate B cells. 3. HIV showsa lot of antigenic variability.Scientists have experimented with different types of vaccine for HIV.One type contains HIV in an inactivated form. A second type contains attenuated HIV which replicates in the body but does not kill host cells.A third type uses a different, non-pathogenic virus to carry genetic information from HIV into the person’s cells. This makes the person’s cells produce HIV proteins. So far, these types of vaccine have not been considered safe to use in a mass vaccination programme.People with AIDS die because they are unable to produce an immune response to pathogens .Explain why this leads to death

Answer 1

1. Infected by/susceptible to (other) pathogen(s)/named disease caused by a pathogen (from environment)2. Pathogen(s) reproduce/cause diease (in host)3. Damage cells/tissues/organs4. Release toxins

Question 2

Explain why the following means that a vaccine might not be effective against HIV.HIV rapidly enters host cells

Answer 2

1. (HIV enters cells) before antibodies can bind to/destroy it2. Antibodies cannot enter cells (to destroy HIV)/stay in blood

Question 3

Explain why the following means that a vaccine might not be effective against HIV.HIV shows a lot of antigenic variability

Answer 3

1. Antigen (on HIV) changes2. (Specific) antibody/receptor no longer binds to (new) antigen