Virus Flashcards
Shared with Human DNA
40% human DNA is viral dna
Cellular reservoir
Survival (mechanism to propagate, haven from environment)
Recombination
Evolution
Features
Not visible not culturable not removed by filtration not complex not treatable with antibiotics small acellular simple construction core nucleic acid viral structure envelope
Viruses only
multiply inside cells can infect bacteria DNA or RNA not both metabolically inert hijack cells dormant phase (provirus) Protein capsid Attachement Envelope Lipid bilayer from the host
HIV
envelope proteins outer lipid from host viral RNA core proteins capsid inside
Envelope
camouflage from immune system
Attachement and entry into cells
more complex envelopes are more sensitive to damage
Naming system
Modern- genome sequence
Disease- HIV TMV
Bacterial Virus- Sigla Code
By shape
Fillamentous viruses
Rod shape
TMV, Ebola
central cone surrounded by protein capsid
helical symmetry
sapsomere- indue. protein unit surround RNA in helix
Icosahedral viruses
appear spherical central core surrounded by 20 side protein capsid more complex 3 axis of summetry complex strength
Nucleocapsid
Core and Capsid
Complex animal viruses
nucleocapsids surrounded w/ envelopes
complex bacteriophage
icosahedral head
multicomponent tail- attach and penetrate
large genomes code for proteins and assembly
Replication
APUSAR
Replication
Adsorbtion
attachment of iron to host
specific host cell receptors
depends on chance
antibodies bind and prevent this step
Replication
Penetration
entry into host cell
plant viruses enter at sites of damage
animal viruses enter by endocytosis or fusion
bacteriophages require mechanism
Replication
Penetration
BACTERIOPHAGE
Tail fibres attach
tail sheets contracts, carries 144 ATP
rigid tail core hollow spike driven through envelope
DNA enters
Replication
Uncoating
decapsidisation
uncoats in cytoplasm by host cell proteases
Replication
Synthesis
Transcription and translation
control protein and inhibits cell expression
replicase: new copies
structural: capsid
Viral?
DNA viruses use host enzymes, RNA uses iron enzymes
Retrovirus: RNA → DNA → Transcribed
ssRNA acts like mRNA
Replication
Assembly
Spontaneous
- economy of effort
- error check
Complex
- requires several capsid subunits
- requires scaffolding proteins
Replication
Release
Host cell dies, iron released
or in bacteria, viral lysosome bursts
enveloped viruses bud through membrane
REMEMBER, some viruses become latent and may insert its genome into host genome (provirus)
Antivirals
Antireplication strategy and vaccinate
Herpes Simplex
HS1 HS2 Varicella Zoster Virus VZV (chickenpox) Epstein Barr Virus EBV Cytomegalovirus CMV
Differences in Herpes
ā wide host range, short life cycle
SENSORY GANGLIA
B restricted range, long life cycle
SECRETORY AND KIDNEY
y narrow range
LYMPHOCYTES
