HIV Flashcards
What is a retrovirus?
A virus that contains the enzyme reverse transcriptase, which causes the reaction that turns viral RNA into a complementary strand of DNA.
After infection, what is the first thing HIV does inside the body?
Binds to a CD4 protein on a host cell. Most typically this is a T-helper cell
After binding to the CD4 protein, what does HIV do next?
The protein capsid fuses to the host cell’s cell-surface membrane and released its RNA and enzymes into the host cell
When inside the cell, what do the RNA and enzymes do?
Turn the viral RNA into a complementary strand of DNA
After the DNA is formed, where does it move to?
the host (T-helper) cell’s nucleus. Here it is inserted into the cell’s DNA
Outline how HIV replicates using Th cells?
- HIV enters the bloodstream
- the attachment proteins on HIV bind to CD4 protein on Th cell’s cell-surface membrane
- the capsid fuses with the Th cell’s cell membrane
- the viral RNA and reverse transcriptase enter the Th cell
- HIV RNA converted into HIV DNA , using reverse transcriptase
- HIV DNA moves into nucleus and binds to Th cell DNA
- HIV mRNA is made, which contains the instructions for the formation of viral proteins (enzymes, attachment proteins, reverse transcriptase, capsid)
- new HIV particle formed
- HIV leaves the Th cell, taking some of it’s cell surface membrane with it (budding)
Why do you wash in between steps in the ELISA test?
to remove any unbound antibodies, preventing false positive results
Describe the structure of the human immunodeficiency virus (HIV)
-RNA (as genetic material);
-Reverse transcriptase;
- (Protein) capsomeres/capsid;
-(Phospho)lipid (viral) envelope
- Attachment proteins;
How is the ELISA test shows the presence of HIV antibodies?
- HIV antigens bound to bottom
- sample added
- HIV antibodies bind to the HIV antigens
- secondary antibodies added with an enzyme attached
- will bind to primary antibodies
- substrate added = colour change
WASH BETWEEN STEPS
How does a control show that the ELISA test has worked?
shows that the sample has diffused/moved
Why are viruses described as acellular and non-living?
- no cell-membranes
- do not respire or synthesise own proteins