HIV Replication and Pathogenesis Flashcards
Where and from what did HIV originate from?
3 separate introductions into the human population from chimps in central africa
How is HIV NOT transmitted?
Casual contact
Exposure by saliva
Blood sucking insects
Most common routes of HIV transmission?
Unprotected sex and sharing needles
What methods of HIV transmission have been basically eliminated?
Mother to fetus transmission and blood transfusion transmission
Most common individual (in the US) to contract HIV?
Yong african american male who has sex with men
T/F: The Ro of HIV is very small
True…few virions breach the epithelium and establish infection
What is the time window to prevent HIV after exposure?
About 1 week
What are the stages of establishing an HIV infection?
1- Virions breach epithelium
2- Virion infect tissue macrophages, dendritic cells, ect (local infection)
3- Infected cells produce visions and the virions migrate to local lymph nodes
4- Virions spread from regional lymph nodes to GALT and other sites (disseminated)
Of those exposed, is a man or a woman more likely to become infected with HIV?
Woman
What type of virus is HIV? Describe the genome.
ssRNA (+)…but dipolid
Significance of HIV’s diploid genome?
Has two copies of every gene…allows for great genetic variation
What cells are HIV virions tropic for?
Early= Macrophages (binds CCR5)
Late= T cells (binds CXCR4)
What allows for the change in tropism?
Mutations as time goes on
What are the 16 stages of HIV lifecycle?
1- attachment and fusion 2- uncoating 3- reverse transcription 4- migration of genome to nucleus 5- integration into host genome 6- mRNA and genome synthesis 7- mRNA export 8- viral protein synthesis 9- genomic RNA export 10- spliced mRNA synthesis 11- viral membrane protein synthesis 12- protein maturation 13- protein accumultion at plasma membrane 14- virion assembly at plasma membrane 15- budding 16- virion maturation
What viral proteins aid in virion attachment to cell membrane? What happens when they bind?
TM and SU
SU binds CD4 and chemokine coreceptor. This causes a conformational change in TM, so that it is now able to insert into target cell and induce fusion.
What transcribes the ssRNA genome into DNA?
viral reverse transcriptase
Describe reverse transcription:
RT is prone to error
tRNA bound to ssRNA is a primer
Templates switch during replication
What happens to the genome after it becomes DNA?
It becomes circular and binds to HIV protein Integrase which has a nuclear localization signal that directs it to the nucleus.
Where does the HIV DNA integrate into the host chromosome?
Site of active genes
What is the primary obstacle to eradicating HIV from a person?
Latencyy
What marks the end of Phase 1 of HIV replication?
Integration
What is used to transcribe HIV mRNA?
Host cell RNA Polymerase II
What marks the end of phase II of HIV replication?
Transcription of viral mRNA
What creates the correct balance of Gag > Gag-pol?
Infrequent ribosomal frame shifting
