3.2.4 HIV Flashcards
What is HIV?
Virus that affects immune system
What is AIDS?
Disease where immune system deteriorates & eventually fails
What cells do HIV infect and use as a host?
helper T-cells
When are people said to have developed AIDS?
When there’s less than 200 mm-3 helper T-cells numbers so body can’t fight usual harmless pathogens (e.g. flu)
HIV has a ______ structure
Spherical
What does HIV’s core contain
RNA & proteins
e.g. enzymes: reverse transcriptase, integrase, and protease
What is HIV’s outer coating of protein called?
Caspid
HIV has a ___ layer called an ______
HIV has a outer layer called an envelope
What is the envelope made out of?
Membrane stolen from cell membrane of previous host cell
What are sticking from the envelope?
Attachment proteins
(Contains glycoproteins)
What do attachment proteins help HIV to do?
To attach to host helper T-cell
What is a retrovirus (e.g. HIV)?
Use reverse transcriptase & RNA method
Describe how HIV replicates
- Attachment protein attaches to CD4 cell-surface antigen on host helper T-cell
- Capsid is released into cell, where it uncoats and releases genetic material (viral RNA) & core proteins into cytoplasm
- Inside cell, reverse transcriptase is used to make complementary strand of DNA from viral RNA template
- From this, double-stranded viral DNA is made & inserted into human DNA
- Host cell enzymes are used to make viral proteins from viral DNA found within human DNA
- Viral proteins are assembled into new viruses (made by host cell), which bud from cell & go infect other cells
What happens during the initial infection period?
HIV replicates rapidly & infected person may experience severe flu-like symptoms
What happens after the initial infection period?
HIV replication drops to a lower level = latency period