Vaccines, Disease & Monoclonal Antibodies (AQA A Level Biology)

Pulmonary tuberculosis (TB) is a contagious bacterial infection that involves the lungs.Pulmonary TB is caused by the bacterium Mycobacterium tuberculosis.

In the UK, children are vaccinated against this disease. What is a vaccine?

Describe how vaccination can lead to protection against pulmonary tuberculosis.

The MMR vaccine is a vaccine against measles, mumps, and rubella (Germa measles). A child was given the vaccine but it took over a week for any antibodies to appear in the child’s blood. Explain why.

Sometime after the first MMR vaccination, the child in part c) was given a second dose of the vaccine as a ‘booster’. Immediately after this second vaccination, the concentration of antibodies in the child’s blood increased. Explain why.

Pertuzumab is a monoclonal antibody used to treat breast cancer. This monoclonalantibody has a radioactive substance attached to it.

What is the advantage of having a radioactive substance attached to the antibody, rather than injecting the radioactive substance directly?

The monoclonal antibody in part a) only binds to cancer cells. Why does it do this and not bind to other cells in the body?

A small number of patients who are given the monoclonal antibody in part a) have an immune response to it. Explain why.

An intravenous drip is used to deliver the monoclonal antibody in part a) directly into vein of a patient. Suggest why it is not given as a drug for the patient to swallow.

Warts are growths on the skin caused by an infection with human papillomavirus. A  medical researcher vaccinated a group of adult patients against human papillomavirus. He gave each patient two doses of vaccine, 5 months apart. The researcher tested three samples of blood from each of the patients:

Sample 1: taken 3 week before the first dose of vaccine

Sample 2: taken 3 weeks after the first dose of vaccine

Sample 3: taken 3 weeks after the second dose of vaccine

He measured the concentration of antibodies against human papillomavirus in the
patients’ blood each time. The results are shown in the graph in Figure 1:

Figure 1

Calculate the percentage increase in the mean concentration of antibodies in blood between samples 2 and 3.

In a trial for a new, improved version of the vaccine in part a), a doctor gave the new vaccine to a group of adult volunteers. The doctor followed the same procedure as in part a), each volunteer was given two doses of vaccine, 5 months apart. As in part a), the doctor tested three samples of blood from each of the patients. Suggest two factors the doctor should have considered when selecting adult volunteers for this trial.

In the graph in Figure 1 there are clear differences between the mean concentrations of antibodies in the three blood samples. Explain these differences.

Give one way in which a pathogen can cause disease when it enters the body of a host organism.

Contrast active immunity and passive immunity. 

When a person is bitten by a venomous spider called a Black Widow spider, the spider injects a toxin into the blood. Antivenin is injected as treatment to spider bites. Antivenin contains antibodies against the toxin. This treatment is an example of passive immunity.

Explain how the antivenin cures a person who has been bitten.

In order to cure someone who has been bitten by a black widow spider (see part b), explain why it is essential to use passive immunity, rather than active immunity.

The antivenin described in part b) is produced by injecting the venom from black widow spiders into horses, which then produce antibodies against the venom. However, some patients have a life-threatening reaction to this horse-made antivenin. A new form of antivenin has been produced by the same process, but using sheep instead of horses. 

Suggest why this new form of antivenin causes fewer reactions in people than that produced using horses.

The diagram in Figure 1 shows a human immunodeficiency virus (HIV).

Figure 1

Name structure B and structure E in Figure 1.

Name structure C in Figure 1 and state its function in this virus.

After HIV has infected a T cell, new HIV viruses are produced. Describe how.

When the new HIV viruses are released from the T cell (see part c), the T cell bursts/lyses and is destroyed. This destruction of T cells is very dangerous and could eventually cause the death of someone infected with HIV. Explain why.

Figure 1 shows the progress of infection when damaged human skin comes into contact with Human Papillomavirus, or HPV.

It can be 6-12 months before HPV antibodies can be detected in the blood of an individual with a HPV infection.  Use Figure 1 to suggest why this is.

There is a vaccination for HPV which is routinely given to teenage girls, as it is thought to offer future protection against cervical cancer. The standard procedure is for each girl to receive three doses of the vaccine for full immunity, although there is some discussion  about the optimum number of doses. Figure 2  below shows antibody production after different doses of HPV vaccine in teenage girls.

Figure 2

A student concluded from Figure 2 that it didn’t matter whether girls were given two  doses of vaccine or three. Evaluate this conclusion.

HPV vaccines provide protection against cancer by preventing the virus from causing mutations in infected cells. Current medical advances in vaccine technology mean that researchers hope that it will soon be possible to vaccinate people against cancer cells themselves. 

Figure 3 shows some of the changes that can take place when a cell becomes cancerous. 

Figure 3

Use Figure 3 to suggest how a vaccine could be effective against the development of cancer. 

Although it is hoped that cancer vaccination might one day be preventative, currently it is being trialled for the treatment of existing cancers rather than for prevention. 

Suggest why these types of therapeutic vaccine could be seen as preferable to more traditional cancer treatments such as chemotherapy.

Figure 1 below shows the structure of the human immunodeficiency virus (HIV).

Figure 1

Suggest the functions of the following HIV components:

Glycoprotein ___________________

Reverse transcriptase __________________

Figure 2 shows some of the changes that take place in the blood after infection by HIV.

Figure 2

Use information in Figure 2 to explain the changes in HIV RNA copies in the plasma  during the first 14 weeks after infection.

Use Figure 2 to explain why those infected with HIV experience an asymptomatic period  (period without symptoms) between 2-10 years. 

Use Figure 2 and your own knowledge to explain how infection with HIV eventually  leads to the development of AIDS.

Figure 1 below shows the events that take place during the progression of a vaccination programme.

Figure 1

Suggest what the ‘adverse events’ labelled in Figure 1 might be. 

Suggest an explanation for the events seen in stage 3 of the vaccination programme in Figure 1.

Towards the end of stage 4 in Figure 1, the disease incidence drops to zero. Explain what needs to happen within the vaccination programme to reach a disease incidence of zero.

Table 1 shows the herd immunity thresholds for several different diseases.

Table 1

Of the diseases listed in Table 1, only smallpox has been fully eradicated. Use information in Table 1 and your own knowledge to suggest why this is the case.

SARS-CoV-2 is the virus that causes COVID-19 disease. Figure 1 below shows the structure of a rapid lateral flow test strip used to test for the presence of SARS-CoV-2 antigens in a person’s nose and throat cells. This kind of test can be carried out at home in around 20 minutes.

Figure 1

Describe and explain the contents of the section labelled ‘conjugate pad’ in Figure 1. 

Explain the function of the control line on the test shown in Figure 1.

Figure 2 below compares the sensitivity of the lateral flow test shown in Figure 1 with  another test called the PCR test at different stages during an infection.  PCR tests are carried out in a laboratory and results can take a few days to be returned. 

Figure 2

A researcher concluded from Figure 2 that PCR tests should be used rather than lateral flow tests. Use this information and detail provided in part a) above to evaluate this conclusion.

The PCR test involves amplifying the genetic material in a swab sample before testing for viral RNA. Use this information and detail provided in part a) above to suggest an explanation for the sensitivity difference between the two tests shown in Figure 2.

A method for the diagnosis of HIV is outlined in Figure 1 below

Figure 1

 Explain how the test in Figure 1 gives a positive result if a patient has an HIV infection.

An important process is missing from the description in Figure 1. Describe the missing  process and explain why it is essential.

HIV infects human cells by binding to a cell surface receptor called CD4. This binding causes a shape change in the viral surface glycoproteins, enabling the virus to enter the host cell. 

A new treatment for HIV involves a monoclonal antibody called Ibalizumab, the action of which is shown in Figure 2 below.

Figure 2

Suggest how Ibalizumab works as a treatment for HIV.

A trial looking at the efficacy of Ibalizumab investigated its impact on CD4 cell (also  known as helper T cell) count after 25 weeks of treatment. The results are shown in Figure 3 and include the standard deviations for each group of patients. 

Figure 3

State and explain what can be concluded about the efficacy of Ibalizumab from the results shown in Figure 3.