Virus structure and replication

what makes up the simplest virus structure

• capsid

• genome(DNA or RNA)

• viron associated plymerase

Can any virus be seen with light microscopy

no

what are 3 general viral properties

• genomes are RNA or DNA

• either naked or enveloped

• obligate intracellular parasites

A virus with a DNA genome has what differences to a virus with an RNA genome

• mostly replicate in the nucleus

• more stable

A virus with a RNA genome has what differences to a virus with an DNA genome

• mostly replicate in the cytoplasm

• high error rate/rate of mutations

What shapes of viral capsids exist

• icosahedral

• helical

Is it possible for a naked helical capsid to exist

no all helical capsids are enveloped

What is the most important property of a naked viral capsid

resistant to environmental influences

Due to being resistant to environmental change naked virus develop what aspects

• retain infectivity upon drying

• can survive GI tract

• must kill host cell to release mature virus

What makes up the envelope of enveloped virus’s

• protein lipid bilayer

• glycoproteins

• receptor binding proteins

A virus envelope that has tight interactions would cause the shape to be __________?

regular

A virus envelope that has loose interactions would cause the shape to be __________?

variable

unlike naked viruses enveloped viruses are sensitive to __________

environmental changes

due to sensitivity to environmental changes enveloped viruses have what aspects

• must stay wet during transmission

• do not need to kill cells in order to spread

The virus depends on the cell for what things?

• protein synthesis

• energy metabolism

• membrane biosynthesis

A cell that has a receptor for a virus and allows it to replicate is both ___________ and ____________

• susceptible

• permissive

receptor binding viral proteins are always __________of the virus

on the surface

The binding of the viral molecule is reversible if the the receptor is __________ or irreversible if _________

• protein

• polysaccharides

what are the steps to the viral replication cycle

1. uptake

2. transport

3. replication

4. assembly

5. exit

What are the 3 forms of viral penetration into a cell

• plasma membrane

• endosomes

• nuclear membrane

identify the types of penetration occurring in the diagrams

1. nuclear membrane

2. plasma membrane

3. endosome

plasma membrane penetration is ____________ and requires a __________

• Ph independent

• viral fusion protein

endosomal penetration is ________

Ph dependent

once uncoated viral particles ________ be retrieved from the cell

can not

what are aspects of viral transport within a cell

• energy dependent transport

• utilize microtubules

• some use actin cytoskeleton

where does amplification of RNA viruses take place what about DNA viruses

• cytoplasm

• nucleus

In order for viruses to reproduce efficiently they utilize cellular machinery to create ___________

inclusion bodies

Inclusion bodes arise from the ___________ of host cell cytoskeletal and membrane compartments

rearrangement

what are the 3 methods of viral particle release in a cell

• budding

• exocytosis

• cell lysis

which exit strategy is used by naked viruses

cell lysis

what is needed to classify a virus via structure

• viral nucleic acid

• capsid structure

• envelope

• size and shape

what is needed to classify a virus via disease

• route of infection

• organ system

• time frame

• spread of infection

a virus with what aspects can be eradicated

• acute infection

• easily identifiable

• effective vaccine

• no reservoir in other species

All DNA viruses amplify in the nucleus with the exception of ___________

Poxviruses