HIV- Exam IV Flashcards
Describe genomic structure of HIV:
positive strand RNA virus
HIV is considered a ____ virus
retrovirus
Why is HIV considered a retrovirus?
because it contains reverse transcriptase enzyme that copies RNA into DNA
HIV causes chronic disease long after infection due to:
integration of viral DNA into host chromosome
Describe the structure of the retrovirus HIV: (4)
- enveloped virus
- HIV matrix proteins surround nucleocapsid
- core conical nucleocapsid
- envelope glycoproteins
HIV has ____ on the surface of the virus
adhesin
The adhesin on the surface of HIV engages with:
a CD4 receptor and a coreceptor (either CCR5 or CXCR4)
In HIV adsorption and penetration, the use of a coreceptor will:
dictate the types of cells that will become infected
Initial HIV infection =
M tropic
HIV infection infecting cells of macrophage lineage with coreceptor CCR5:
M tropic (initial infection)
HIV infection infecting T-cells with use of coreceptor CXCR4:
T tropic (later during infection)
Later HIV infection =
T tropic
What is the adhesin on the surface of HIV that binds to CD4 receptor?
viral ENV protein gp120
In HIV infection, when the coreceptor is engaged, what does this allow for?
The virus to become more closely positioned to the cell surface/membrane
After the coreceptor is engaged in HIV infection, allowing for close proximity of virus to cell surface/membrane, what occurs?
a second viral protein gp41 comes into contact with host cell membrane to promote viral fusion
What would occur in the absence of coreceptor binding by gp120?
low infectivity of HIV
How was it discovered that a coreceptor is necessary for infectivity of HIV?
a small number of individuals in the population are resistant to HIV infection
In HIV infection, coreceptor interactions is essential for:
GP41 contact and viral fusion with host cell
The individuals in the population who are resistant to HIV infection lack:
coreceptors
HIV penetration is due to:
membrane fusion promoted by gp41
retroviruses like HIV do not undergo:
an initial phase of translation
The penetration of the nucleocapsids into the cytoplasm of the host cell has to do with the interaction of:
viral gp41 protein with host cell membrane
Once the gp120 binds to the CD4 & to the coreceptor this allows the gp41protein to be close enough to the host cell membrane to undergo a ____ that causes part of the gp41 protein to engage both the _____ but also the ____.
conformational change; viral envelope; host cell membrane
Following Gp41 engagement with both viral envelope and host cell membrane, a subsequent conformational change pulls the viral envelope and host cell membrane together to ____ and allows the delivery of ____.
fuse; the viral nucleocapsid into host cell cytoplasm