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Flashcards in HIV Deck (10):

What are AIDS?

AIDS (acquired immune deficiency syndrome) caused by infection with HIV
A syndrome is a collection of sympotoms related to the same cause
Symptoms of AIDS - opportunistic infections - susceptible due to weakened immune system


Whats HIV?

Complex virus - RNA surrounded by 2 sided protein capsid enclosed in a layer of viral protein
Lipid envelope formed from host cell membrane
2 copies of mRNA


Describe transmission of HIV

Not tough virus and can't survive outside the body for long
Bodily fluids have to be transferred directly into the next body by:
sharing needles, unprotected sex, blood to blood transfer through cuts, transmission through breast milk


New virus particles destroy T cells

New HIV virus proteins produced with glycoproteins and nuclear material are assembled into new viruses
New virus bud out of T cell taking some cell membrane with them as their envelope and killing the cell as they leave
Infected T helper cells will be destroyed by T killer cells
As number of viruses increases, number of T helper cells decrease so macrophages B cells and T killer cells aren't activated so immune system deficient


Describe Acute Phase of HIV

HIV antibodies appear in blood
Symptoms - fever, sweats, headache.
Rapid replication of virus and loss of T helper cells
After a few weeks infected T helper cells are recognised by T killer cells destroying them
Reduces rate of replication


Describe Chronic Phase of HIV

Virus continues to reproduce rapidly but numbers are kept in check by immune system there may be no symtoms and dormant diseases ie TB may reactivate


Describe Disease Phase of HIV

Increases viral load and decline in T helper cells indicate onset of AIDS
Immune system is now compromised due to lack of T helper cells and patient is more prone to opportunistic infections ef TB


Diagnosis of HIV

HIV test
Gay men and black African men are more prone to get it
Early treatment
Blood test
Look for antibodies


Treatment of HIV

Cannot be treated as virus hides in T helper cells
Antiretroviral drugs - reduce viral production
Protease inhibitors - inhibit proteases catalyses cutting of proteins
Reverse transcriptase inhibitors


Describe HIV replication

HIV invades T helper cells
Glycoprotein molecule, gp120, on viral surface bind to CD4 receptors on T helper cell surface
Envelope surrounding the virus fuses with T helper cell membrane enabling viral RNA to enter the cell