Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

83 Cards in this Set

  • Front
  • Back
All retroviruses can insert thier genome into host's for germline transmission (T/F)
retroviruses can be oncogenic (T/F)
How man genera in retrovirus family?
HIV belongs to the ___ genera
How are the symptoms of AIDS characterized?
susceptibility to opportunistic pathogens

Kaposi's sarcoma

B cell lymphoma
Avarate time from initial time of infection to disease is longer in individuals infected with HIV-_
Describe the retrovirus genome
diploid, two identical ssRNA
T/F: retrovirus DNA is synthesized and processed by the host cell mRNA 'handling machinery'
retrovirus DNA is associated with a specific ___ (____) which is used to prime replication
What does the retrovirus use tRNA for?
to prime replication
T/F: retrovirus RNA lacks a 5' cap and a 3' polyA tail
F. It has both of these
What is the gene order in all retroviruses?
HIV is classified as a ___ retrovirus because it contains additional genes involved in regulation of virus expression
Retroviruses are (enveloped|non-enveloped) viruses approximately ___ nm in diamater
110 nm
SU (surface) protein = gp___
What are SU and TM derived from?
TM (transmembrane) protein = gp___
SU and TM connected by a ___ bond
SU and TM are derived from ___ gene
SU is involved in ___
receptor binding
TM is involved in ___
membrane fusion
HIV nucleocapsid classified as ___ in structure
CA (capsid) protein derived from ___ gene
The two RNA molecules of HIV are protected by ___
nucleocapsid proteins
Between the capsid (CA) and the envelope is the ___ protein
MA (matrix)
MA is derived from ___ gene
proteolytic cleavage of gag gene product
RT and IN come from ___ gene
the protease (PR) responsible for cleavage of gag and pol gene products is encoded in ___ gene
When does PR become activated?
When the virus has budded from the cell
What are the products of the gag gene?
What are the products of the env gene?
What are the products of the pol gene?
What is the function of IN?
integrates viral DNA into host genome
What is the function of RT?
makes dsDNA from ssRNA
SU and TM work as a team. SU is used for ___, and TM is used for ___.
receptor binding
membrane fusion
What is the HIV receptor? Co-receptor?
CD4 surface molecule on T helper cells and some macrophages

chemokine receptor CXCR4 (T cells)
CCR5 (macrophages)
What is the function of CD4 in T cells?
it is a co-receptor to the T-cell's antigen receptor
Viral strains of HIV are assigned into groups based on what?
the co-receptors used

the groups are: R5, X4
Do chimpanzees see a decline in immune system functionality after HIV infection?
How is HIV transmitted?
intimate contact of body fluid
How is HIV spread to the target organs?
bloodstream in the blood plasma and/or within lymphocytes or macrophages
What systems are targeted by HIV?
What are the critical cellular targets of HIV?
dendritic cells (antigen presenters)
CD4-positive T lymphocytes
What is the function of CD4+ T cells?
activation of macrophages (to kill intracellular pathogens)
activation of B cells (Ab production)
T/F: macropages also function as antigen presenting cells
HIV replication cycle: Begins with attachment of viral glycoprotein ___ to ___
gp120 (SU) to CD4 cell surface marker
HIV replication cycle: After gp120 binds to CD4, ___ or ___ is recruited to the site and also binds the virus.
CCR5 (macrophages)
CXCR4 (T cells)
HIV replication cycle: After binding of gp120 to receptor and co-receptor, ___ inserts itself in ___, causing fusion of virus envelope with host cell membrane
gp41 (TM)
host cell membrane
HIV replication cycle: After fusion of virus envelope with membrane of host cell, ___ is released into the cytoplasm
virus core
HIV replication cycle: The DNA intermediate that is produced by the RT is known as a ___
T/F: RT is an enzyme unique to Retroviruses
What are two activities of RT?
RNA dependent DNA polymerase
RNase (enzyme to degrade RNA)
RT of the RNA genome: RT uses a ___ as a primer to make a DNA copy of the RNA genome
RT of the RNA genome: What does RT initially create?
DNA:RNA hybrid molecule
RT of the RNA genome: What happens to the DNA:RNA hybrid created?
most of the RNA is removed, but just enough is left to use as a primer for synthesis of the complementary DNA strand
RT of the RNA genome: What removes the RNA portion of the hybrid DNA:RNA?
RNase H
RT of the RNA genome: What is used as a primer for the complementary DNA strand?
A portion of the RNA left by the RNase H
HIV replication cycle: What is the "pre-integration complex"?
provirus + integrase
HIV replication cycle: What does the integrase portion of the "pre-integration complex" do?
catalyzes integration of provirus into host cell DNA at random site
HIV replication cycle: After integration into genome, the (host | virus) cell enzyme RNA polymerase II "takes over" replication and transcription
HIV replication cycle: What does host cell RNA polymerase II do?
takes over replication and transcription of viral genome using integrated provirus as template
What takes over replication and transcription of viral genome using integrated provirus as template?
RNA polymerase II from the host cell
___ ribosomes translate HIV mRNA to produce Env proteins
The Env proteins are transported through the ___ where they are glycosylated and cleaved to form the ___ and ___ complex
SU and TM (freshly made) are localized to ___
the plasma membrane of infected cell
T/F: HIV lyses the cell to escape
F. It buds off.
During or shortly after budding, HIV undergoes a maturation process mediated by ___
PR (protease)
What does protease do during HIV maturation?
cleaves specific sites in the Gag and Gag/Pol polyprotein, resulting in a morphologically distinct core
When the ribosome starts translation at the 5' end, and stops at the stop codon, what is produced?
the Gag precursor, cleaved to yiled MA, CA, NC, and PR
T/F: The Gag and Gag/Pol precursors are cleaved immediately after translation.
F. They are cleaved much later, during the maturation process (during budding or shortly after)
When the ribosome slips at the first stop codon in the retroviral mRNA (__% of the time), what is produced?
The Gag/Pol precursor (recall, the Pol portion gives rise to RT and IN)
How are env gene products made?
splicing out the gag and pol genes like introns (inside the nucleus), then translation on the rough ER
In what part of the cell is the env mRNA portion spliced out of the retroviral mRNA?
After translation on the rough ER, what happens to the env gene product?
passed thru Golgi
cleaved into SU and TM
inserted in cell membrane
T/F: most cases of primary HIV infection are asymptomatic
Symptoms of primary HIV infection may include...
influenza-like illness lasting 2 weeks
What is the termed used to describe production of Ab to HIV virus during primary infection?
How long can the asymptomatic period of HIV infection last?
many years
What is AIDS defined as?
< 200 CD4+ cells per microlitre
What are five of the immune system abnormalities seen with AIDS?
less Ab responses
less MHC class II expression
less CD4+ T cells
less IL-2
What are the two models used to explain AIDS caused by HIV?
Direct Cell Killing: immune system kills cells expressing viral antigens

Antigenic Diversity: New antigenic variants of HIV continually arising overwhelms immune system, causing collapse
What are potential vaccine candidates for HIV?
inactivated virus (may not be suitable due to denaturing of epitope on glycoprotein, and safety concerns)

subunit vaccines
synthetic peptides
DNA vaccines
What are the two classes of HIV antiviral drugs?
RT inhibitors: AZT looks like a nucleotide after cell phosphorylates it to AZT-TP, but has an azide group instead of hydroxyl. Blocks DNA synthesis.

Protease inhibitors: inhibit HIV-1 protease, preventing maturation of virus.