Vaccines,HIV and Monoclonal antibodies Flashcards
What is a vaccine
- Injection of antigens from attenuated (dead or weakened) pathogens
- Stimulating formation of memory cells
Explain how vaccines provide protection from diseases
- Specific B Lymphocyte with complementary receptor binds to antigens
- Specific T helper cell binds to antigen presenting cell and stimulates B cell
- B lymphocyte divides by mitosis to form clones
- some differentiate into B plasma cells which release antibodies
- Some differentiate into B memory cells
- On secondary exposure to antigen, B memory cells rapidly divide by mitosis to produce B plasma cells
- These release antibodies faster and at a higher conc
Explain how vaccines provide protections for populations against diseases
Herd immunity-Large proportion of population vaccinated, reducing spread of pathogens
-Large proportion of population immune so do not become ill from infection
-Fewer infected people to pass a pathogen on/unvaccinated people less likely to come in contact with someonewith a disease
Describe the difference between active and passive immunity
Active immunity:Initial exposure to antigen e.g. vaccine or primary infection
Memory cells involved
Antibody produced anf secreted by plasma B cells
Slow takes longer
Long term immunity as antibody can be produced in response to a specific antigen again
Passive immunity no exposure to antigen
No memory cells involved
Antibody introduced from another organism e.g. breast milk/ across placenta from mother
Faster acting
Short term immunity as antibody hydrolysed
Explain the effect of antigen variability on disease and disease prevention
Antigens on pathogens changes shape/tertiary structure due to gene mutation
SO no longer immune from vaccine or prior infection
B memory cell recpetors cannot bind to/ recognise changed antogen on seconday exposure
Specific antibodies not complementary/ cannot binbd to hanged antigen
Describe the structure of a HIV particle
Lipid envelope
RNA
Reverse transcriptase
Capsid
Attachment protein
Describe the replication of HIV in helper T cells
- HIV attachment proteins attach to receptors on Helper T cell
- Lipid envelope fuses with cell surface membrane releasing capsid into cell
- Capsid uncoats, releasing RNA and reverse transcriptase
- Reverse transcriptase converts viral RNA to DNA
- Viral DNA inserted/incorpated into helper T cell DNA (may remain latent)
- Viral protein/capsid/enzymes are produced
-a) DNA transcribed into HIV mRNA
-b) HIV mRNA translated into new HIV proteins - Virus particles assembled and released from cell (via budding)
Explain how HIV causes the symptoms of acquired immune deficiency syndrome (AIDS)
Hiv infects and kills helper T cells (host cell) as it multiplies rapidly
-So T helper cells cant stimulate cytotoxic T cells, B cells and phagocytes
-So B plasma cells cant release as many antibodies for agglutination and destruction of pathogens
Immune system deteriorates–> more susceptible to opportunistic infections
Pathogens reproduce, release toxins and damage cells
Explain why antibiotics are ineffective against viruses
Viruses do not have metabolic processes (e.g. do not make protein)/ribosomes
Viruses do not have bacterial enzymes/murein cell wall
What is a monoclonal antibody
Antibody produced from genetically identical/cloned B lymphocytes/plasma cells
So have the same tertiary structure
Explain how monoclonal antibodies can be used in medical treatments
- Monoclonal antibody has a specifc tertiary structure/binding site/ variable region
- Complementary to receptor/protein/antigen found only on a specific cell type
- Therapeutic drug attached to antibody
- Antibody binds to specific cell forming antigen-antibody complex, delivering drug
extra info: some monoclonal antibodies are also designed to block antigens/receptors on cells
Explain how monoclonal antibodies can be used in medical diagnosis
- Monoclonal antibody has a specifc tertiary structure/binding site/ variable region
- Complementary to receptor/protein/antigen found only on a specific cell type
- Dye/stain/fluorescent marker attached to antibody
- Antibody binds to receptor/ protein/antigen,forming antigen-antibody complex
What is active immunity?
- Immunity created by your own immune system following exposure to the pathogen or its antigen
- active immunity can be split into two: Natural active immunity and Artificial active immunity
What is Natural active immunity
- Folllowing an infection the body creates antibodies and memory cells
What is artificial active immunity
*Following the introduction of a weakened version of the pathogen or antigens via a vaccine
What do the B cells do when there is an exposure to foreign antigens?
The b cells go through clonal selection
They undergo mitosis to make large numbers of cells
These differentiate into plasma cells or memory B cells
What is AIDS (Acquired immune deficiency syndrome)?
When the relocating viruses in the Helper T cells interfere with their normal functioning of the immune system
Why is AIDS deadly
With the helper T cells being destroyed by the viruses the host is unable to produce adequate immune response to other pathogens and is left vulnerable to infections and cancer
It is the destruction of the immune system that leads to death rather than the HIV directly
What is direct monoclonal antibody therapy?
A type of targeted medication
Monoclonal antibodies with a binding site complementary in shape to the antigens on the outside of cancer cells
The antibodies are given to cancer patients and attach to the cancer walls
Whilst the antibodies are bound to the cancer antigens.This prevents chemicals binding to the cancer cell which enable uncontrolled cell division Therefire monoclonal antibodies prevent the cancer cell growing and as they are denoted to only attach to cancer cells they do not cause harm to other normal cells
What can monoclonal antibodies be used to test for
Pregnancy
Influenza
Hepatitis
Prostate cancer
Chlamydia
indirect monoclonal antibody therapy
Cancer can also be treated with monoclonal antibodies complementary in shape to the antigens in the outside of cancer cells which have drugs attached to them
These cancer drugs are therefore delivered directly to cancer cells and kill yhem
This reduces the harmful side effects that traditional chemotherapy and radiotherapy can produce. this is often referred to as bullet drugs
