Viral Replication and HIV Flashcards
virion still detectable in
- adsorption and penetration
no intracellular virions detectable
- eclipse period
progeny virion formation
- maturation
no extracellular infectious virus detectable
- latent period
budding, exocytosis, or following necrosis
- release
adsorption
- specific and nonspecific interactions between virus attachment proteins and cellular receptors
two types of entry
- receptor mediated endocytosis
- membrane fusion
viruses that enter via receptor mediated endocytosis
- adenovirus
- orthomyxovirus
- rhabdovirus
ROAR
viruses that enter via membrane fusion
- herpesvirus
- HIV
- parainfluenza
MF HHP
uncoating
- nucleocapsid is modified or disrupted to allow transcription of mRNA
- allow genome to serve directly as mRNA
site of replication is _____ dependent
- virus dependent
DNA viruses replicate where? exception?
- nucleus
- Poxvirus
RNA viruses replicate where? exception?
- cytoplasm
- retroviruses and influenza
importance of expression of early genes
- required to initiate viral replication
- protein products of early transcription needed to initiate viral genome replication
progeny nucleocapsid formation
- accumulation of structural proteins in same cellular compartment where replication of progeny genomes occurs
capsid formation
- self-assembly or
- requiring scaffold proteins
for naked DNA and RNA, INFECTIOUS progeny formation occurs when
- once genomes are encapsidated
maturation
- an additional step required for enveloped viruses
internal envelopment where
- ER
- Golgi
internal envelopment and exocytosis viruses
- herpesvirus
- coronavirus
- bunyaviruses
- poxiviruses
BUNNY has HERPES and POX but is okay INSIDE because he’s chillin with a CORONA
cell surface envelopment viruses (budding)
- rhabdoviruses
- togaviruses
- orthomyoxivurses
- paramyxoviruses
- retroviruses
RPTOR - REPTAR FROM RUGRATS All the rugrats were best buds. - budding don't want to get mixed up with Reptar Retro because Rugrats is retro Toga because they wear a diaper
egress/release directionality
- has implication for pathogenesis
directionality
- apical
- baso-lateral
pathogenesis
- localized
- disseminated infections
egress/release enzymes
- function to complete the release and maturation process
cytopathic effect
- alteration in the appears of the infected cells or even cell death
when a uniform cell monolayer is exposed to a few infectious virus particles, what develops
- visible plaques
- areas of CPE
how to plaques in CPE develop
- radially from initially infected cells to surrounding uninfected cells
human retroviruses
- enveloped RNA viruses
- reverse transcriptase
- integrase
human lentivirus example
- HIV-1
- HIV-2
HIV-1 vs HIV-2
- HIV-1 more common
- HIV-1 more pathogenic
four groups
HIV-1,
- M
- O
- N and P
HIV-1 M sutypes
- A-H
which subtype predominates in the US
- subtype B
GP 120 HIV
- HIV adsorption protein
- associates with GP41 (transmembrane protein)
P24 HIV
- main capsid antigen
- combination tests look for P24 can detect HIV infection a week earlier
major proteins of HIV
- reverse transcriptase
- integrase
- HIV protease
primary receptor for HIV
- CD4
co-receptors for HIV
- CCR5
- CXCR4
CD4 receptors located on
- T lymphocytes
- macrophages
- microglial cells
sequences within V3 loops of gp120 determine
- coreceptor usage
CCR5 using viruses
- M-tropic
- R5 viruses
- most of HIV today
CXCR4 using viruses
- T-tropic
- X4 virus
- Mostly in AIDS
HIV entry mediated via
- interactions of Env gp120/gp41 with CD4
- conformation change of gp120
conformational change of gp120
- interaction with chemokine receptor
- conformational change of gp41
conformational change of gp41
- penetrates the cell
coreceptor switch
- switch of CCR5 to CXCR4 during disease progression
first step of reverse transcription
- reverse transcription of ssRNA to proviral DNA
second step of reverse transcription
- RNAse H degrades RNA
third step of reverse transcription
- second strand of DNA produced resulting in dsDNA
the enzymatic activities on HIV RT enzyme
- RdDp
- DdDp
- RNaseH
HIV virion half life in blood
- 30 minutes
how many mutations per viral copy
- at least 1
high viral replication =
more frequent mutations
every single point mutation occurs
daily
how DS DNA viruses replicates
example
- herpes virus
- enter nucleus directly
how +ssRNA virus replicates
example
- polio
- +ssRNA acts mRNA
- translated by host ribosomes to make viral polymerase
- proceeds with replication events
how -ssRNA virus replicates
example
- flu
- use carry own viral polymerase to carry out replicative events
integrase
- helps identify integration site on host DNA
- executes strand transfer to get integrated into chromosome
protease
- cleavage and particle maturation
