micro - virus stuff Flashcards
What is an obligate intracellular parasite?
VIRUS!!!!
What is the point of vaccines?
generate enough anti-viral compounds to prevent multiplication within the body
What is a virion?
the infectious virus particle in viruses - contain nucleic acid genetic material surround by a protein coat (CAPSID); some viruses also have a lipd and glycoprotein ENVELOPE
What do you need to know about genomes?
- can be either DNA or RNA and ss or ds - ss RNA genomes can have the same (+) or complimentary (-) polarity as viral m-RNA (ie - if (+) polarity, can go straight to being made!!!!! if (-) polarity, the complimentary strand must first be made - may be linear or circular; some linear RNA genomes are segmented - viral genomes are usually haploid - just the retroviruses are diploid

What are capsids?
- The capsid and genome of enveloped viruses is called a nuceocapsid
- Capsids or nucleocapsids are composed of many copies of one or very few viral-encoated protein subunits
- Capsids function in packaging of the nucleic acid in viral assembly and protection of the nucleic acid
- Capsids of naked viruses contain the viral attachment protein (VAP)
What are the 2 shapes of capsids?
cylindrical (helical form)
cubic (icosahedron form)

How are capsomers arranged?
in penton capsomers (surrounded by 5)
in hexon capsomers (surrounded by 6)
What is the envelope?
- Composed of lipids, proteins and glycoproteins
- Specific glycoproteins act as VAPs for enveloped viruses
- Acquired from viral-modified cellular membranes during egress of virus from host cell
- Is disrupted in non-moist environments or by heat, acid and lipid solvents

How many virus families have human pathogens and now many contain DNA?
Human pathogens are found in 21 families; 7 families contain DNA
What is VAP?
viral attachment proteins found on the virion; allow virus to get into next cell
on envelope virus found in membrane
in naked virus (no membrane), part of capsid protein
(always what’s external)
Very important!
How are viruses classified?
basis of
nucleic acid
virion structure
replication strategy
Viruses in the same family can:
produce diverse diseases (chicken pox, herpes, mono)
Viruses in the same families can…
produce the SAME disease
Which is the only diplo virus?
retrovrirus - AIDS (2 strands of +sense DNA)
There are __________ for viruses to replicate.
there are DIFFERENT WAYS for viruses to replicate - more complex ways for RNA.
whole point = they must replicate to cause disease. We want to stop them.
What does host range depnd on?
1) can a virus enter a cell
2) can virus find appropriate cellular machinery
3) can virus exit cell
What is a productive virus?
one that yields new infectious viruses
What is a non-productive virus?
viral genetic material persists in a cell (latent state) but no infectious viruses is formed
Some non-productive infections can lead to oncogenic transformation of cells.
What are the phases of viral muliplication?
1- attachment
2- penetration
3- uncoating
4- virus component synthesis
5- assembly
6- release
- if not attached, won’t cause diease. Disease shows up where it’s possible to attach -
The synthesis of viral proteins and viral effects on host macromolecular synthesis often result in morphological changes to the host cell collectively known as cytopathic effects (CPE), ex., cell rounding, cell fusion, etc.
Antivirals inhibit some step in the viral multiplication process

Where do RNA viruses generally replicate and what are the exceptions?
in the cytoplasm - except for the Aids virus (retro-virus; must go to nucleus) and the influenza virus (needs enzymes found only in nucleus of cell).
Where do DNA viruses normally replicate?
in the nuclues
What are viroproteins?
small, hydrophobic virus-encoded proteins that oligomerize at host cell membranes where they are involved in enveloped virus budding and non-enveloped virus cellular lysis.
even without lysing the cell, they’ve just made the cell incapalbe of doing its job
have several cytopathogenic effects on the cell including
- formation of hydophilic pores
- alterations of calcium and hydrogen gradients.
Viral specific membranes host cytoplasmic membrane. Nucleocapsid migrates, buds, is released
Since virus messes with the cell membrane, now is recognized as foreign and killed by immune recepters. Dead cells cause disease…






