Monoclonal Antibodies, HIV and Elisa Test Flashcards
What are monoclonal antibodies?
Identical antibodies, have the same tertiary structure and the same antigen binding site. Produced in large amounts from a single clone of anti-body producing cells.
How are monoclonal antibodies made?
Usually from fusing a specific B cell with a cancer cell. The hybrid cell will divide to produce a clone of cells all producing the same specific antibody.
What are monoclonal antibodies used for?
- Detects the presence of specific antigens in body fluids to diagnose if a person has a particular disease.
- Detects the presence of specific antibodies produced by a person against an antigen
- Targets cancer cells which are then destroyed by drugs activated by cells labelled by these antibodies
What are the key terms of HIV?
HIV capsid= Bullet shaped core that contains RNA
HIV envelope= Outer surface
HIV enzyme= Proteins that carry out steps in life cycle
HIV glycoproteins= Protein spikes embedded in envelope
HIV RNA= Genetic material
Describe the structure of HIV
Contains a lipid envelope with attachment proteins. Inside the envelope is a capsid that encloses two single strands of RNA and the enzyme reverse transcriptase which catalyses the production of DNA from RNA which is why it’s a retrovirus
How does HIV replicate?
It instructs host cells to produce requirements.
1) HIV circulates the body in the bloodstream
2) Attachment binds to to CD4 protein found on Th cell
3) Protein capsid fuses with cell membrane, RNA & reverse transcriptase enter Th cell.
4) Reverse transcriptase converts the virus’ RNA to DNA which is inserted into cell DNA .
5) DNA creates mRNA which contains instructions for making new viral proteins
6) Proteins make HIV particles break away from Th cell using a piece of its cell membrane which from lipid envelopes
How does HIV cause AIDS?
- By killing/ interfering with Th cells. Infected people can’t stimulate B cells or Tc cells. Sufferers are susceptible to secondary infections and cancers. HIV doesn’t kill directly.
- Infections of lungs, intestines, brain and eyes are common, symptoms include weight loss and diarrhoea
What is the ELISA test?
A test that uses antibodies to detect antigens in a sample, can be used to detect HIV and tuberculosis. Can measure the quantity of an antigen.
How does the ELISA test work?
1) Apply a sample to the surface where antigens will attach and then wash the surface to remove unattached AG
2) Add complimentary antibody which will bind to the antigen. Wash surface to remove unattached AB.
3) Add secondary AB which binds to first AB. Second AB has an enzyme attached.
4) Wash to remove unbound second AB.
5) Add the colourless substrate to the sample. If the enzyme is present, an enzyme substrate complex forms and substrate becomes a coloured product
6) Amount of antigen present is relative to intensity of colour
Why are antibiotics ineffective against viruses such as HIV?
Antibiotics weaken the cell wall and burst the cell, but viruses don’t have metabolic pathways/ cell structures so antibiotics are ineffective. Also have a protein coat, not a murein cell wall. Viruses are within an organisms cells so antibiotics can’t reach the virus.
