Why aren’t all vaccines 100% effective?
vaccines are dependent on the individual’s immune response, so some immune systems may not generate an adequate response
Why type of virus is HIV?
a retrovirus
Why discovered HIV?
Gallo and Montagnier
What is happening to the CD+ T lymphocytes during acute HIV syndrome?
As RNA copies rapidly increase, CD+T cell count decreases
What occurs during the classical latency phase of HIV?
virus is in the body but mostly inactive, however CD+ T cells are still slowly declining
What causes HIV to lead to death?
because CD+ T cells are so low, an opportunistic disease will lead to death
When does AIDs develop in HIV?
when the CD+ T cell count drops extremely low
Why is there no cure for AIDs yet?
- complex replication
- high mutation rate due to RT enzyme error
- evolves into quasispecies
- antigens are constantly changing
Describe the structure of HIV.
- enveloped
- two copies of +ssRNA
- six accessory proteins
- diploid
- spike protiens: transmembrane (anchor envelop to matrix) and surface subunit (binds to host receptor)
How does HIV enter host cell?
gp120/gp41 spike protein complex binds the host CD4 receptor of T cells to CCR5 to induce conformation change and fusion peptides fuse viral and host membranes together
What can cause people to be resistant to HIV?
A defective CCR5
Describe HIV replication cycle.
- HIV fuses to membrane and protein capsid dissolves
- RT uses +ssRNA to make dsDNA
- dsDNA integrates into host DNA
- viral RNA transcripts are made and exported to cytoplasm for translation and synthesis of viral proteins
- virus particles are assembled and viral proteins cleave most tethering to release virions without cell lysis
What are the two methods that HIV uses to infect cells?
- regular HIV binding and replication
- budding directly from one infected cell to another (formation of syncytia)
Why does the replication cycle of HIV have a high mutation rate?
RT is very error prone
What is immune escape?
the constantly changing of envelope antigens
What causes progression to AIDS?
- insertion of viral genome into host genome may destroy host gene regulation
What might potential anti-HIV drugs do?
- prevent fusion of viral and host membrane
- inhibit RT, integrase, or HIV protease
What is AZT?
an anti-HIV drug that blocks RT activity
What is Fuzeon?
an anti-HIV drug that blocks fusion of HIV envelop with host cell plasma
How does HIV progress from HIV to AlDS?
tumor formation, lysis, persistent infection, latent infection, and cell fusion
