lecture 9-virus

Question 1

noncellular infectious agents, gene info surrounded by protein coat, obligate intracell parasite

Answer 1

viruses

Question 2

virus living?

Answer 2

according to Darwin, yes, being able to reproduce and mutate, even tho not on own

Question 3

average size of virus is _____

Answer 3

20-300nm

Question 4

structural comps of viruses?

Answer 4

nucleic acid core, protein coat, envelope

Question 5

what is capsid?

Answer 5

shell consisting of individual protein subunits called capsomeres

Question 6

naked viruses have ___ attached to capsid, while enveloped ones have them on the envelope

Answer 6

glycoprotein spikes

Question 7

host range determined by:

Answer 7

presence of receptors and suitable metabolic machinery in cell

Question 8

virus life cycle;

Answer 8

1) adsorption 2) penetration/uncoating 3) gene expression 4) assembly 5) release

Question 9

two types of penetration/uncoating?

Answer 9

1) receptor mediated endocytosis (naked), receptor mediated fusion (enveloped)

Question 10

assembly happens in:

Answer 10

nucleus or cyto

Question 11

release of naked virus?

Answer 11

assemble in cyto, released after lyse host cell

Question 12

ex. of naked?

Answer 12

rhinovirus (cold)

Question 13

release of enveloped?

Answer 13

envelope acquired during virus release from host cell and partly of host cell origin by by budding, chronic stress on cell, cell targeted by immune system

Question 14

outcomes of viral infection?

Answer 14

lytic acute infection, persistent chronic infection, latent infection, oncogenic infection

Question 15

what is latent?

Answer 15

viral nucleic acid insert into host cell chrom, not expressed, reactivate at future time

Question 16

what is oncogenic?

Answer 16

host cell transformation–>cause host cell grow uncontrolled way (15% of human cancers caused by this)

Question 17

mechanism of oncogenesis?

Answer 17

virus nucleic acid inserted into host chrom and disrupt ability control growth; proteins produced during replicating inhibit/destroy factors used reg. cell growth

Question 18

antivirals do not kill ___ virus, only act to block making of ___ progeny

Answer 18

pre-existing; new

Question 19

antiviral examples block viral adsorption/penetration:

Answer 19

1) block viral adsorption/penetration, selzentry (HIV), docosanol (Herpes)

Question 20

antiviral block uncoating of viral NA

Answer 20

amantadine (flu), pleconaril (rhinovirus)

Question 21

antivirals that block viral gene express and replication

Answer 21

viral polymerase inhibitors (foscarnet), nucleoside analogues (acyclovir)

Question 22

acyclovir used against ___ and administered as ___

Answer 22

herpes; inactive “pro-drug”

Question 23

acyclovir converted to active by ______ during infection

Answer 23

thymidine kinase produced by HSV

Question 24

examples of drugs which block assembly/release?

Answer 24

protease inhibitors, neuramindase inhibitors

Question 25

what are proteases?

Answer 25

enzymes encoded by some viruses for synth and assembly of viral structural proteins

Question 26

what are neuraminidases?

Answer 26

enzyme encoded by flu virus which is needed by virus to be released from host cell

Question 27

what is natural anti-viral?

Answer 27

Interferon—small peptides produced by infected cells that diffuse out and signal to other cells to make anti-virals (innate immunity)

Question 28

most stuff target ____ step

Answer 28

gene expression

Question 29

probs with antivirals?

Answer 29

toxicity to host, latent not susceptible, some drugs much less effective if given late, resistance quick, development of new agents hard and unethical