Download Intro to Virology

Intro to Virology
1. Define a virus
a. Obligate intracellular parasites (selfishly uses at its own benefit)
b. Do not possess ribosomes – no translation
c. Uses the hosts replication machinery
2. Define how the terms virion and virus differ
a. Virion is the infectious particle
b. Serves to transfer the viral genome
3. Identify the components of a virion
a. Genome
i. DNA
ii. RNA
b. Capsid (protein)
i. Cubic (icosahedral – buckyball)
ii. Helical
iii. Complex
c. Matrix (protein)
i. Layer between capsid and envelope
d. Envelope
i. Lipid bilayer (host) with glycoprotein (virus) external layer surrounding nucleocapsid
ii. Virions are either enveloped (herpies) or naked (parvo, polio)
iii. Envelope viruses are ether (or alcohol) sensitive - detergents
4. name the families of viruses that infect humans
Virus
Genome
Naked/envel Capsid
Segmentation
Notes
Parvoviridae
Circoviridae
Naked
Polyomaviridae
Icosahed
DNA
Adenoviridae
Herpesviridae
Enveloped
Poxviridae
Complex
Picornaviridae
Naked
Caliciviridae
Icosahed
+ RNA
Flaviviridae
Messenger
Togaviridae
Enveloped
Coronaviridae
Helical
Rhabdoviridae
Paramyxovirinae
MonoParamyxoviridae
Pneumovirinae
negavirales
– RNA
Filoviridae
Compliment
Enveloped
Helical
Bornaviridae
To mess.
Orthomyxoviridae
Influenza
Bunyaviridae
Segmented
Arenaviridae
Double stranded
Reoviridae
Naked
Multiple
(+ & -)
RNA  DNA on the
Hepadnaviridae
way in (Hepatitis)
RNA reverse
Enveloped
Icosahed
transcriptase
DNA  DNA on the
Retroviridae
way out (HIV)
5. describe how virus families are organized
6. list in order the steps in the viral replication cycle
a. Absorption or attachment
i. Receptor on cell surface
ii. Occurs at 4˚C
iii. Determines host range or tropism
b. Penetration
i. Occurs at cell surface – pH independent
ii. Occurs after receptor-mediated endocytosis – pH dependendant (actin cytoskeleton is
involved)
c. Uncoating
i. Separation of genome from the outer structural component of the virion
ii. Now no longer infective
d. Synthesis
i. Virus genome directs cell to synthesize both
1. Structural proteins
2. Non-structural proteins
e. Assembly
i. Non-enveloped virus can accumulate in cell and be released when cell dies
ii. Enveloped viruses acquire their envelope by budding through a membrane of the cell
(released in the same step)
f. Release