Immunity - Antigens / vaccines / HIV

Question 1

What can Antigens help the immune system identify (4)

Answer 1

-Pathogens
-Cells from other organisms of the same species
-Abnormal body cells
-Toxins

Question 2

Antigen def.

Answer 2

Molecules ( usually proteins ) that can generate an immune response when detected by the body.

Question 3

Describe the effect that antigenic variability has on vaccination programmes (4)

Answer 3

-New strains of viruses are formed regularly due to antigenic variability
-Memory cells from vaccination will not recognise these new strains as they are immunologically distinct.
-Every year new strains in the population require a new vaccine
-New vaccines are developed, and the most suitable is chosen and implemented in a programme of vaccination

Question 4

What effect does antigenic variability have on immune response ?

Answer 4

-Upon a reinfection, the memory cells from the first infection will not recognise the antigens from the second
-So immune system has to carry out primary immune response, giving more time for disease/symptons to occur

Question 5

What is antigenic variability ?

Answer 5

Different antigens are formed on cell surface membrane of pathogens ( due to changes in genes of pathogen )

Question 6

What are some ethical issues associated with vaccination?

Answer 6

-Testing on animals
-Testing on humans dangerous e.g. people think they’re protected when they’re not
-If there was an epidemic, difficult decisions over who first receives vaccine

Question 6

What are some ethical issues associated with vaccination?

Answer 6

-Testing on animals
-Testing on humans dangerous e.g. people think they’re protected when they’re not
-If there was an epidemic, difficult decisions over who first receives vaccine

Question 7

What are some examples of points you could bring up when evaluating methodology in a vaccine question ?

Answer 7

-sample size, larger sample size = more reliable results
-repeatability, comment on how repeatable experiment is, perhaps looking at specifics in question

Question 8

How do vaccines protect individuals from disease?

Answer 8

-vaccines contain antigens which stimulate your body to produce memory cells against a particular pathogen, without the pathogen causing disease
-Therefore you are immune, so upon reinfection secondary immune response will get rid of pathogen before symptons occur

Question 9

How can vaccinations help protect populations from disease?

Answer 9

-Vaccination of individuals reduces occurence of disease
-So unvaccinated people less likely to catch disease,
-this is herd immunity

Question 10

What is active immunity ?

Answer 10

Immunity from your immune system making making its own antibodies after being stimulated by an antigem

Question 11

What is passive immunity?

Answer 11

Immunity when you’re given antibodies from a different organism

Question 12

What are four differences between active and passive immunity?

Answer 12

-A. immunity requires exposure to antigen, p. does not
-A. immunity takes a while for protection to develop, p. is immediate
-A. immunity produces memory cells, p. does not
-A. immunity offers long term protection, p. does not ( as antibodies in A. immunity are produces by memory cells which remain present in body fluids )

Question 13

What are the Natural and Artificial types of active immunity?

Answer 13

-Natural- immune after catching disease
-Artificial - vaccination

Question 14

What are the Natural and Artificial types of passive immunity?

Answer 14

-Natural- baby immune due to antibodies received from mother
(through placenta or breast milk)
-Artificial - immune after injected by antibodies from someone else

Question 15

How does HIV replicate inside T -cells

Answer 15

-HIV reverse transcriptase converts the virus RNA into DNA

-The newly made DNA moves into the helper T cell’s nucleus where it is inserted into the cells DNA
-HIV DNA in nucleus creates mRNA using cells enzymes.
-This mRNA contains the instructions for making new viral proteins and the RNA for new HIV
-The mRNA passes out of the nucleus through a nuclear pore and uses the cell’s protein synthesis mechanisms to make new HIV molecules

Question 16

How does HIV cause symptoms of AIDS?

Answer 16

-Kills helper T cells so host unable to withstand simple infection, dies

Question 17

Why does HIV bind to TH cells ?

Answer 17

-A protein on HIV readily binds to a protein called CD4. Whilst this protein occurs on a number of different cells, HIV most frequently attaches to TH cells.

Question 18

Where is HIV following infection

Answer 18

-Folowing infection,HIV enter blood stream, circulates around body

Question 18

Where is HIV following infection

Answer 18

-Folowing infection,HIV enter blood stream, circulates around body

Question 19

First stage of HIV with TH cell.

Answer 19

-Protein on surface HIV binds w/ CD4 on TH
-The protein capsid fuses with the CSM. -The RNA and enzymes of HIV enter the TH cell.

Question 20

How does HIV damage TH cells?

Answer 20

-HIV breaks away from TH cell with a piece of its cell-surface membrane surrounding them which forms their lipid envelope.
-This is Budding

Question 21

How does HIV cause symptoms of AIDS?

Answer 21

-HIV virus causes AIDS by interfering with normal function of Th cells, damaging the immune system

Question 21

How does HIV cause symptoms of AIDS?

Answer 21

-HIV virus causes AIDS by interfering with normal function of Th cells, damaging the immune system

Question 22

How can someone be HIV positive but not have AIDS?

Answer 22

-HIV virus causes AIDS, but may not have destroyed sufficient Th cells to cause AIDS

Question 23

How can someone be HIV positive but not have AIDS?

Answer 23

-HIV virus causes AIDS, but may not have destroyed sufficient Th cells to cause AIDS

Question 24

Why don’t antibiotics work on HIV?

Answer 24

-Viruses dont have their own ribosomes or enzymes to inhibit, which is how antibiotics work by inhibiting these in bacteria

Question 24

Why don’t antibiotics work on HIV?

Answer 24

-Viruses dont have their own ribosomes or enzymes to inhibit, which is how antibiotics work by inhibiting these in bacteria