Intro To Virology Flashcards
(19 cards)
What is a virus
- Latin : poison
- intracellular, smaller then bacteria (<1um), simple, rely on host for replication (rely on host’s ribosomes)
- VERY FEW can be seen with light microscopy. We don’t know much about them
- we do not know any that carry ribosomes
- do have the ability to evolve
History Hallmarks
- Louis Pasteur = father of microbiology, well known for his vaccine work
- Koch and Pasteur proposed “germ theory”
- Koch postulates: framework for investigating disease
Koch Postulates
- agent must:
1) be present in every case of dz
2) be isolated from host and grow in vitro
3) dx must be reproduced then pure cultivated agent is introduced into healthy host
4) same agent must once again be recoverable from newly infected host
ICTV nomeclature rules
- order
- family
- subfamily
- genus
- species
viral classification
- virion architecture
- viral nucleic acid and replication strategies
- phylogenomics
- antigenic relationships
- biologic characteristics
virion architecture
- nucleocapsid size
- nucleocapsid shape
- nucleocapsid symmetry
- enveloped (capsid + nucleic acid enclosed in protein coat) vs naked (glycoprotein studded phospholipid membrane)
are enveloped or naked virus more fragile ?
ENVLOPED ! they do not survive well outside host, more susceptible to disinfectants
nucleocapsid symmetry
- ->symmetrical
- helical: tubular with subunits
- icosahedral: 20 equilateral triangular faces
- ->non-symmetrical
- complex
- filamentous
- pleomorphic
viral nucleic acid and replication strategies
-mRNA is the central molecule for viruses (to make protein) BUT can be single/double stranded DNA/RNA
Class I viruses
dsDNA genomes
- papillomaviridae
- adenoviridae
- herpesviridae
- poxyviridae
- asfaviridae
Class II viruses
ssDNA genomes
- circoviridae
- parvoviridae
Class III viruses
dsRNA genomes
- reoviridae
- birnaviridae
Class IV viruses
ssRNA + genomes (already in mRNA)
- picornaviridae
- caliciviridae
- coronaviridae
- areriviridae
- flaviviridae
- togaviridae
Class V viruses
ssRNA - genomes
- orthomyxoviridae
- paramyxoviridae
- rhabdoviridae
- filoviridae
- bunyaviridae
Class VI and VII viruses
reverse transcriptase
- hepadnaviridae
- retroviridae
antigenic relationships (serology)
- relates to Hemagglutinin and Neuraminidase properties of the virus subtype
- H#N# (vaccine only works for that specific subtype of the virus)
biologic characteristics
- based on tropism/ mode of transmission (lots of overlap)
1) enteric
2) respiratory
3) arboviruses (natural vectors - mosquitos and ticks)
4) oncogenic (by close contact, injection, fomites)
generalized viral lifecycle
1) attachment
2) penetration
3) uncoating
4) replication
5) replication
6) transcription
7) translation
8) assembly
9) release
what does a virus do when its inside the cell
- cause necrosis and apoptosis
- cell transformation
- no discernible effect
