Virology Flashcards
binds CD4, CCR5, CXCR4 on T cell or Macrophage cell membrane to mediate HIV attachment
Gp120
When is CCR5 bound and where is it found?
Early infection by Gp120
on MQ
aka R5 strains
When is CXCR4 bound and where is it found?
Late infection by Gp120
on T cells
aka X4 strains
Homozygous CCR5 mutation =
immunity to HIV
Heterozygous mutation CCR5 =
Slower course of HIV
Reverse transcriptase of HIV synthesize ____ which integrates into host genome
dsDNA
encodes reverse transcriptase (RT), integrase (IN), protease (PR)
Pol (polymerase)
encodes HIV capsid (p24) and matrix (p17) proteins
aka CORE proteins
Gag
HIV uses _____ for fusion and entry
gp41
Four-1 = Fus1on
what codes for gp120 and gp41 in HIV which are formed from the cleavage of gp160
env (envelope) gene
Diploid genome 2 molecules of RNA
HIV
HIV AB-immunoassays during acute HIV infection phase to detect viral ___
and IgG ABs to _____
How to confirm HIV during serologic window phase
p24 Ag capsid
IgG ABs to HIV1/2
Nucleic acid testing (NAT aka PCR) for HIV RNA becomes [+] earlier than p24/antibodies (i.e. in the serologic window) → useful for confirming acute HIV infection
1-2 months what is seen in Acute HIV infection serology? HIV RNA CD4+ CD8+ Anti–gp120 AB
High RNA load ( It’s over a thousand!!!!)
Low CD4+ (~500)
Normal CD8+
Rising Anti–gp120 ABs
0-1 month what is seen in window period of HIV serology? HIV RNA CD4+ CD8+ Anti–gp120 AB
Rising HIV RNA (may not be detectable)
Falling CD4+ (~700-800)
Normal CD8+
No Anti–gp120 AB
What CD4+ count = AIDS
<200
During clinical latency HIV replicates in the
Lymph Nodes
What kind of RNA virus is HIV (+/–)
+ RNA (2 copies)
HIV encodes reverse transcriptase an _____ polymerase which transcribes ___ into ___
RNA-dependent DNA Polymerase
(1) single-stranded viral RNA
(2) double-stranded DNA
The HIV virion has a _____ capsid composed of subunits of ___ (capsid protein)
conical capsid
p24
The HIV virion contains a protective shell composed of subunits of ___ (matrix protein)
p17
gp41 is a _____ protein and gp120 is and _____ protein
transmembrane
outer
CCR5 or CXCR4 are _______ co-receptors
chemokine
HIV can be transmitted sexually, parentally (IVDU), and _____ during ___, ___, ___,
vertically (i.e. mother to infant)
pregnancy, delivery, or breastfeeding
Early in HIV infection, patients may develop acute retroviral syndrome, which presents with
Fever/ Flu-like symptoms
HIV infection is followed by clinical latency, an asymptomatic period lasting ____ years
8-10
*HIV RNA levels are constant during this time
catalyzes the integration of double-stranded viral DNA into host cell DNA
Integrase
The envelope precursor protein gp160 is processed in the host cell ______ and ______ to gp120 and gp41
endoplasmic reticulum
Golgi apparatus
cleaves most viral polyproteins into functional proteins
protease
Neutralizing IgG antibodies primarily target ___
gp120
gp120 exhibits a high degree of ___________, preventing the host from mounting an effective immune response
Antigenic variation
gp120 is heavily _______, protecting it from immune surveillance
glycosylated
competitively bind reverse transcriptase → prevention of nucleotide binding → inhibition of DNA elongation
Nucleoside reverse transcriptase inhibitors (NRTIs)
allosterically bind reverse transcriptase → change in conformation of active site → prevention of DNA elongation
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
bind integrase, preventing the incorporation of viral DNA into host cell DNA
Integrase inhibitors (bictegravir, dolutegravir, elvitegravir, raltegravir)
NOTICE (TEGRA)
Side effects of ______ include neurological and psychiatric symptoms and muscle breakdown (check a CK level if your patient complains of soreness)
Integrase inhibitors
____ inhibitors prevent cleavage of gag and pol polyproteins by viral protease.
The gag and pol polyprotein product is cleaved into individual functional proteins at the ___ of the viral budding process. The proteolysis step is critical for the creation of mature, infectious virions.
Protease
end
blocks the CCR5 co-receptor, preventing HIV from entering the cell
Maraviroc (an entry inhibitor)
Determine the HIV _____ prior to starting maraviroc, since it binds exclusively to CCR5 and not CXCR4
tropism
binds gp41, preventing the fusion of the HIV membrane and the host cell membrane
Enfuvirtide (fusion inhibitor)
In most cases, HIV treatment regimens should begin with an _____ inhibitor + 2 ____
integrase
NRTIs
(ex: dolutegravir + tenofovir and emtricitabine)
