HIV Flashcards
What is structure of HIV
Structure of HIV is
Glycoproteins on outside and a lipid bilayer (this is HIV envelope derived from host membrane) this makes it an enscapulated virus (due to lipid coat)
Underneath this, it has a layer of viral protein
Capsid (made from protein) contains viral proteins (e.g reverse transcriptase and integrase) and 2 identical copies of mRNA
How does HIV replicate
HIV replicates following steps
1) HIV glycoproteins GP120 bind to CD4 receptors of White blood cells
2)reverse transcriptase copies viral RNA and from this, forms virus DNA
3)integrase inserts virus DNA into host DNA
T helper cells burst when virus particles leave cell
This will lead to more T helper cells getting infected
How can HIV be transmitted
HIV can be transmitted through bodily fluids e.g blood, vaginal secretions and semen but not saliva/urine.
Ways HIV is passed
Ways HIV is passed on are
Infection from sharing needles
Unprotected sex
Blood to blood transfer
What are T helper cells
T helps cells come in 2 forms
T helper cells which when activated, stimulate B cells to divide and become cells capable of producing antibodies.
T killer cells, these destroy any cells with antigens on their surface membrane that are recognised as foreign
What happens during acute phase of infection
During acute phase of infection,
HIV antibodies appear after 3-12weeks
Infected person experiences symptoms (fever,sweats,headache) or none
Rapid duplication of virus and loss of T helper cells
After a few weeks, infected T helper cells are recognised by T killer cells, which start to destroy them, greatly reducing rate of virus replication
What is AIDS
AIDS is acquired immune deficiency syndrome and is caused by infection with HIV. Symptoms are those of infections to which patient becomes susceptible as their immune system is weakened.
What is integrase
Integrase is an enzyme that inserts virus DNA
What is the chronic/latent phase
Chronic/latent phase is when virus continues to reproduce rapidly, but numbers are kept in check. May be no symptoms but increasing tendency to suffer colds and other infections which are slow to go away.
Dominant diseases like TB activate
What is the disease phase
Disease phase is when number virus in circulation increases and a declining number of T helper cells indicates onset of AIDS
What are opportunistic infections
Opportunistic infections are diseases that take advantage of weakened immune system from HIV
What is a retrovirus
Retrovirus is a virus which has reverse transcriptase
How is HIV treated
HIV could be treated by drugs which bind to and alter shape of gp120.
Could also be treated with drugs that bind to CD4 receptors on membrane which prevents virus from binding to T helper cells
What is an effect on component of blood of having less T helper cells
Effect on component of blood is B cells not activated.
