Lecture 1: General Virology 1 Flashcards
Define a virus and how does that compare to bacteria
- Filterable (virus - <200um) – retain bacteria but allow smaller (0.22um)
- Obligate intracellular (depend on host mechanisms)
- No organelles (can acquire non-functional ribosomes from host)
- either DNA/RNA
- Require electron microscopy to view
Bacteria can have independent metabolism, they are larger, and have DNA/RNA, can see with light microscope
Which virus has organelles
arenavirus
non functional ribosome
2 types of viral structure
- Naked: genome + protein coat (capsid)
- Enveloped: genome + protein coat + lipid bilayer
What is a Pasteur-Chamberland filter
- 0.1 – 1 um
- Remove all bacteri/cells from liquid suspension
Which type of viral structure can you remove easily by washing hands
enveloped
o Lipid bilayer makes it more vulnerable to desiccation/detergents vs naked
How does a virus get an envelope
o Viral enveloped from host cell membrane
o Bilayer contains virus coded membrane proteins – genome and capsid move into the bilayer with the glycoproteins
o Virus can acquire host proteins in bilayer
o Proteins in bilayer determine range and antigenic composition
What is the largest and smallest virus
Pithovirus sibericum - 1.5 um
Human papilloma virus - 100nm
What virus has the largest genome
pandora virus
1 um
2.5 million bp
What are bacteriophages
viruses that infect bacteria
o Used as biological control agent – specific
o No relevant associated animal diseases
What large virus can act like a bacteria
acanthamoeba polyphagia mimivirus
large size
“mimic microbe” - gram stains positive like bacteria
What is the smallest virus?
circovirus
What is the largest virus? (mammal)
poxvirus
What is the largest virus? (amoeba)
pithovrius
How are virus naming classifications organized? 2 ways
- Linnaean hierarchical system (phylum/class/order…) –
o should not be used for virus – high mutation rate/small genome
o can’t classify beyond the order (class/phylum) - can use family/genus/species
use the ICTV (international committee of taxonomy of viruses)
* order: - virales
* family: -viridae
* subfamily: -virinae
* genus: -virus
* species: -virus
Baltimore classification
o dsdNA
o ssDnA
o dsDNArt
o dsRNA
o ssRNA
o ssRNA(-)
o ssRNA(+)
o ssRNArt
based on genome and method of transcription
Which dsDNA virus carries its own transcriptase/enzymes for transcription
- most use host enzymes for transcription except pox virus – carries own enzymes