HIV Flashcards
What does HIV stand for?
Human Immunodeficiency Virus
What are the 2 types of HIV?
HIV-1: worldwide, more transmissable
HIV-2: West Africa (mostly)
What is the host cell specificity of HIV?
Th lymphocytes and macrophages
What are the viral proteins of HIV?
gp120 and gp41
What are the two host co-receptors?
CD4 (always) and either CXCR4 or CCR5
What causes the mortality of HIV?
-loss of cell-mediated immune responses
-opportunistic secondary infections
When was HIV/AIDS first reported?
1981
Where was HIV first reported?
metropolitan area in the US and Europe
What is the genome of HIV?
2 strands of positive single stranded RNA: diploid
What are retroviruses?
use RNA-dependent DNA polymerase (reverse transcriptase) to produce double stranded DNA from a viral genome having 2 copies of single-stranded RNA
How many total genes are in HIV?
9
What are the 3 structural genes of HIV?
gag
pol
env
What does gag encode?
capsid proteins (p24) and matrix proteins (p17)
What does pol encode?
reverse transcriptase
integrase
protease
What does env encode?
spike proteins; gp120 and gp41
What is the function of spike proteins?
They are needed to bind to host cell receptors
What are the 4 accessory genes of HIV?
nef
vif
vpu
vpr
What does nef do?
represses host MHC (tells host not to express MHC-1)
What does vpu do ?
destroys CD4 protein of host cell (need CD4 to let virus in- stops immune system from binding to CD4)
What does vif do?
inactivates cell defense
What does vpr do?
transports HIV genome to nucleus
What are the significant HIV proteins?
outside virion and inside virion
What is outside virion?
spike proteins enable binding to hos co-receptors (CD4)
INCLUDES gp120- highly variable & gp41
What is an inside virion?
Enzyme, RNA-dependent DNA polymerase (RT)
Enzyme, Integrase
Enzyme, Protease
What are the two types of ELISA?
Direct and Indirect
What is direct ELISA?
Looking for antigen in the sample
What is indirect ELISA?
looking for antibodies vs specific antigens
True or False:
ELISA is not sensitive
False- ELISA is very sensitive
True or False:
ELISA can’t detect low amounts of antigens or antibodies
False- ELISA can detect low amounts of antigens and antibodies
What is genetic instability?
extremely high rates of mutation (an error- prone to reverse transcriptase)
True or False:
Recombination occurs among HIV subtypes
True
How does HIV evolve in the host?
Starts as one strand of HIV and progresses to many
What changes happen in the evolution of HIV in the host?
host cell tropism
drug resistance
evasion of immune defenses
difficulties with creating potential vaccines (due to changes in antigens)
What are the steps of the HIV replicative cycle?
attachment
penetration
uncoating
biosynthesis
maturation
release
What happens in the biosynthesis phase?
reverse transcription using RT
migration to nucleus and integration using integrase
normal transcription to make 2x +ssRNA
Processing of precursor polypeptide using protease
What are different HIV treatment strategies?
Inhibit reverse transcriptase
Inhibit protease
HAART
What is HAART?
Highly Active Anti-Retroviral Therapy
-“AIDS cocktail” (3 or more drugs in combination)
Track response (CD4) & VIRAL LOAD
Not a cure
What is anti-retroviral therapy?
evaluate treatment via….
CD4+ lymphocytes & viral load
-avoids selection of resistant viral strands
What are the treatment problems of Anti-retroviral therapy?
complex & individual regimens
patient tolerance of drugs
drugs expense
no vaccine/no cure
What is the Immune system avoidance?
-mutation & recombination (antigenic variation)
-antibodies neutralize but are not protective
-integration of viral DNA into host chromosome
What is the suppression of host immune responses?
hef proteins -> decrease MHC-1 expression -> lower Tc function -> suppressed cell-mediated immunity -> fewer HIV infected cells killed
