B3-071A Retroviruses and HIV-1 Flashcards
oncogene hypothesis
viral and oncogenic material exist as genetic elements
Class I: Retrotransposons
Two stages:
DNA to RNA by transcription, then RNA to DNA by reverse transcription
Class 2: DNA transposons
cut from genome by a transposase and inserted into another region of the genoma
is HIV-1 enveloped?
yes
HIV is _______, meaning it contains 2 copies of the viral RNA
diploid
HIV contains a ___________ enzyme
reverse transcriptase
are retroviruses endogenous or exogenous?
both :)
HIV-1 evolved from
SIVcpz
the ___ group resulted in the HIV-1 pandemic
M
HIV-2 evolved from
SIVsm
HIV-1 is further classified into subtypes based on
env and gag genes
how many subtypes of HIV-1 are there currently?
9
which subtype of HIV-1 is most prevalent?
subtype C
p24 is the
capsid protein
p17 is the
matrix protein
HIV-1 has the _____ gene, while HIV-2 and SIV are missing it
vpu gene
p7
nucleocapsid protein
p17, p24, p7, and p6 are encoded by the _____ gene
gag
p10
protease
p66, p51
reverse transcriptase
p32
integrase
p10, p66, p51, and p32 are encoded by the ____ gene
pol
rev and tat are located in the ____ gene
env
gp120, gp41
envelope glycoprotein
gp120 and gp41 are encoded by the ____ gene
env
transactivation of viral and cellular genes
tat
regulation of RNA splicing and promotion of export of mRNA to cytoplasm
rev
alteration of cell activation signals; down regulation of CD4 and MHC1 from the cell surface
nef
virion infectivity, inhibits cytidine deaminase activity
vif
causes cells to enter G2 arrest; transport of pre-integration complex into the nucleus
vpr
decrease surface expression of CD4, facilitates virion release, has ion channel activity
vpu
gp160
env precursor molecule
where is gp160 synthesized
RER
after synthesis, gp160 is transported to the
golgi
gp160 is cleaved by ______ into gp120 and gp41
a host enzyme
the envelope glycoprotein of HIV-1 binds to the
CD4 receptor and coreceptor
what is responsible for the fusion of viral and host cell plasma membrane during viral entry?
gp41
the env is responsible for determining the cell ______ of various isolates
tropism
in early infection [cell type] are infected via the [receptor]
macrophages, CCR5
CCR5+ cells include
macrophages
T cells
Langerhans cells
in late stage infection [cell type] are infected via [receptor]
T cells; CXCR4
CCX4R5
infects both CD4 t cells and macrophages
gp120 binds to
CD4, then CCR5
gp41 induces a conformational change forming the
prehairpin intermediate
when the virus enters the cell and is uncoated
reverse transcriptase converts it to linear ds DNA
integrase
integrates the viral DNA into the host cell DNA
is an HIV-1 virus mature at exocytosis?
no, need viral protease to form nucleocapsid
set point
level of viremia at the end of acute stage of infection
the higher the set point the _______ progression into AIDS
faster
mean time from infection to AIDS is
10 years
the primary stage of infection is characterized by
non-specific prodrome
headache, muscle ache, sore throat, fever, lymphadenopathy, malaise, GI upset
clinical latency
asymptomatic period
is there replication in the asymptomatic period?
yes, constant
constant turnover of infected T cells
gradual decline of circulating CD4 T cells during the asymptomatic phase is due to
constant turnover and reinfection of new T cells
towards the end of the asymptomatic period there is an
increase in viral load
AIDS is defined as
a CD4 count <200
OR
being HIV-1 positive with an AIDS defining illness
protozoal AIDS opportunistic infections
toxoplasmosis, crytosporidosis
fungal AIDS opportunistic infections
PJP
candidiasis
crytococcosis
histo
coccidiodo
bacterial AIDS opportunistic infections
mycobacterium avium
atypical mycobacterial disease
salmonella septicemia
recurrent pyogenic infections
viral AIDS opportunistic infections
CMV, HSV, VZV, EBV, PML
HAND
viruses in CNS become M-tropic (instead of T cell tropic) and target microglia cells
rapid progressors develop AIDS within
2-3 years
rapid progressors have _______ viral set point
high
long term nonprogressors maintain CD4 counts for
> 7 years
viremic controllers maintain CD4 counts
<500
elite suppressor or controllers maintain
undetectable viral loads without ART
can virus be isolated from elite suppressors?
yes
initial screening test for HIV
antibody
or
antibody/antigen tests
confirmatory assays are done via
western blot traditionally, but multispot assay more recently
if the multispot is negative or indeterminate
NAT
despite ART treatment ____________ persists
low level replication
the size of the reservoir of virus in effectively treated patients may be as low as
10^6 to 10^7 infected cells
after discontinuation of ART
virus replication rebounds