Topic 2-HIV Flashcards
What is a retrovirus?
A group of viruses which have the ability to make DNA from RNA as they have reverse transcriptase
What does HIV stand for?
Human immunodificency virus
Is HIV transmitted by a vector (like malria)?
No
Where is HIV unable to survive?
Outside of the human body
How is the virus transmitted?
direct exchange of body fluids:
-sexual intercourse
-blood donation
-sharing of needles used by intravenous drug users
-from mother to child across the placenta
-mixing of blood between mother and child during birth
-from mother to child through breast milk
-Structure of HIV
What is the structure of HIV?
-Two RNA strands
-Proteins (including the enzyme reverse transcriptase)
-A protein coat (capsid)
-A viral envelope consisting of a lipid bilayer and glycoproteins
-The lipid bilayer is derived from the cell membrane of the host helper T cell that the particle escaped from
-Attachment proteins
When the virus enters the bloodstream it infects a certain type of which lymphocyte?
Helper T cells
How does HIV avoids being recognised and destroyed by lymphocytes?
by repeatedly changing its protein coat
How does HIV multiple (At this stage, the individual is HIV positive and will have antibodies against the virus)?
-Viral RNA enters the cell
-Viral reverse transcriptase enzymes produce a DNA copy of the viral RNA
-The DNA copy is inserted into the chromosomes of the cell
-Each time the cell divides it copies the viral DNA
-The infected cells remain normal as the viral DNA is inactive
After a period of time (possibly years) the viral DNA within the host cells becomes active, explain how
-It takes control of the helper T cell
-More HIV particles are produced
-This causes the helper T cell to die
-As a result, thousands of new HIV particles are released which are able to infect other helper T cells
Gradually the virus reduces the number of helper T cells in the immune system, what two effects does this have?
B cells are no longer activated
No antibodies are produced
