Vaccines, Immunity, Monoclonal Antibiodies

Question 1

What is Passive Immunity?

Answer 1

• antibodies are introduced into the body
• pathogen doesn’t enter the body, so plasma cells and memory cells are not made
• no long-term immunity

Question 2

What is active immunity?

Answer 2

• created by your own immune system following exposure to the pathogen or its antigen
• Natural Active Immunity - following infection and the creation of antibodies and memory cells
• Artificial Active Immunity - following introduction of weakened version of pathogen or antigens (vaccine)

Question 3

What are vaccines?

Answer 3

• small amounts of weakened pathogen or antigens introduced to the body (injection)
• exposure to antigen activates B cell to go through clonal expansion and differentiation (clonal selection)
• B cells undergo mitosis to make a lot of cells, these differentiate into plasma cells or memory B cells
• Plasma cells make antibodies

Question 4

What is herd immunity?

Answer 4

• if enough of the population are vaccinated, the pathogen cannot spread easily amongst the population
• provides protection for those who are not vaccinated

Question 5

HIV structure?

Answer 5

• Core - genetic material (RNA) and the enzyme reverse transcriptase, which are needed for viral replication
• Capsid - outer protein coat
• Envelope - extra outer layer, made from membrane taken from host’s cell membrane
• Protein attachment - on exterior of envelope to enable virus to attach to host’s helper T cell

Question 6

Replication if HIV in helper T cells

Answer 6

• HIV transport around blood until it attaches to a CD4 protein on helper T cells
• HIV protein capsule fuses with helper T cell membrane - enables RNA and enzymes from HIV to enter
• HIV enzyme reverse transcriptase copies viral RNA into a DNA copy and moves to helper T cell nucleus (retrovirus)
• here mRNA is transcribed and helper T cells starts to create viral proteins to make new viral particles

Question 7

What is AIDS?

Answer 7

• HIV positive is when a person is infected with HIV
• AIDS is when the replicating viruses in the helper T cells interfere with their normal functioning of the immune system

Question 8

What are Monoclonal Antibodies?

Answer 8

• Single type of antibody that can be isolated and cloned
• Antibodies are proteins which have binding sites complementary in shape to certain antigens
• Used in medical treatment, diagnosis and pregnancy tests

Question 9

What is Direct Monoclonal Antibody Therapy?

Answer 9

• Monoclonal Antibodies designed with binding sites complementary in shape to antigens on outside of cancer cells
• Antibodies given to cancer patients and attach to cancer cells. While bound to cancer antigens, this prevents chemicals binding to cancer cells which enable uncontrolled cell division (tumours)
• don’t cause harm to other normal cells

Question 10

What is Indirect Monoclonal Antibody Therapy?

Answer 10

• monoclonal antibodies with drugs attached to them
• cancer drugs delivered directly to cancer cells and kill them - reduces harmful side effects that traditionally come from chemotherapy and radiotherapy
• ‘bullet drugs’

Question 11

Monoclonal Antibodies - Medical Diagnosis

Answer 11

MAs can be used for:
- pregnancy
- influenza
- hepatitis
- Chlamydia
- prostate cancer
(E.g. COVID 16 antibody test)
Works via an ELISA test

Question 12

What’s the ELISA test?

Answer 12

• ELISA - Enzyme Linked Immunosorbent Assay
  Uses two antibodies:
• first mobile antibody, complementary to antigen being tested for, has coloured dye attached
• second antibody complementary in shape to antigens on the outside is immobilised in the tes
• third antibody is immobilised and is complementary in shape to first antibody

Question 13

Steps of ELISA test

Answer 13

1. Adds test sample from patient to base of beaker
2. Wash to remove any unbound test sample
3. Add antibody complementary in shape to antigens testing for in the test sample
4. Wash to remove any unbound antibody
5. Add second antibody complementary in shape to first antibody, and binds to first. Second antibody has enzyme attached to it. Rinse unbound antibodies off.
6. Substrate for enzyme (colourless) is added - produces coloured products I presence of the enzyme
7. Presence of colour indicates presence of antigen in test sample and intensity of colour indicates quantity present.

Question 14

What are the ethical considerations of monoclonal antibodies?

Answer 14

• requires mice to produce antibodies and tumour cells - whether use of animals is justified to enable better treatment if cancers in humans and to detect disease