3-Virology

Question 1

virus

definition

Answer 1

tiny acellular obligate parasite
-nucleic acid/genome + protein coat/capsid

Question 2

how viruses replicate

Answer 2

assembly of pre formed components NOT binary fission (like bacteria)

Question 3

virus components

Answer 3

genome (segmented or continguos)+ capsid surrounded by
1. matrix/tegument
2. envelope
3. viral attachment proteins

Question 4

genome types

Answer 4

DNA- single or double
RNA- single (neg or pos sense) or double

Question 5

pos sense ssRNA

Answer 5

can be recognized to make proteins

Question 6

neg sense ssRNA

Answer 6

not recognized for protein syn right away
-need to be turned into pos sense

Question 7

ssDNA families

Answer 7

1. parvoviridae

Question 8

dsDNA families

Answer 8

1. papillomaviridae
2. polyomaviridae
3. adenoviridae
4. herpesviridae
5. poxviridae
6. hepadnaviridae

Question 9

HAPPY

mneumonic

Answer 9

H = herpes, hepadna

Question 10

dsRNA families

Answer 10

1. reoviridae

Question 11

-ssRNA families

Answer 11

1. ortomyxo
2. paramyxo
3. rhabdo
4. bunya
5. arena
6. filo

Question 12

+ssRNA

Answer 12

1. matona
2. flaviv
3. corona
4. retro
5. picorna
6. calici
7. hepe

end in viridae

Question 13

RNA virus properties

Answer 13

1. labile and transient bc easier to kill
2. repl in cytoplasm
3. cells cannot rep RNA- viruses must encode an RNA dependent RNA polymerase or have it packaged in virion itself
4. prone to mutation so evade immune sys

Question 14

capsid shapes

Answer 14

-helical/tube/slinky
-icosahedral, like letter die
-complex, mixture of helical and icosahedral

Question 15

naked capsid viruses

non enveloped

Answer 15

-spread easily, survive in adverse conditions even if dry out, resistant to detergents

-kill cells that they infect bc released by lysis

-all gastroenteritis viruses non eveloped

Question 16

enveloped viruses

Answer 16

-adapted to rely on lipid layer for infectious so must stay in moist environ
-not survive GI tract, disrupted by pH
-not need to kill cell to spread

Question 17

life cycle summary

Answer 17

1. attachment
2. entry

Question 18

direct fusion

Answer 18

attachment and entry simultaneous
-enveloped viruses only

Question 19

receptor mediated endocytosis entry

Answer 19

for non enveloped viruses
-lysis vesicle after endocytosed

Question 20

transcription

DNA

Answer 20

mRNA productin dep on genome-

dsDNA good bc can use transcription machinery
ssDNA similar just extra step to make ds

Question 21

transcription +ssRNA

Answer 21

no enzyme needed to convert to mRNA
-still need RdRp encoded
can directly produce protein

Question 22

transcription retroviruses

Answer 22

reverse transcribe into dsDNA

Question 23

viral RdRp

Answer 23

for -ssRNA and dsRNA to convert to mRNA
-ssRNA needs to carry RdRp in virion too

Question 24

-ssRNA mneumonic

Answer 24

always
bring
polymerase
or
fail
replication

Question 25

assembly process

Answer 25

1. indiv viral proteins form into capsid subunits 2. subunits combo for complete capsid 3. viral genome selectively packaged 4. envelope acquired 5. exit cell 6. mature

Question 26

budding

Answer 26

way to leave cell -pushes thru plasma membrane then pinched off

Question 27

point mutation accumulation

Answer 27

from poor proofreading capacity of many viral polymerases -if change produces advantage for virus

Question 28

viral recombination

Answer 28

use cell's machinery to combine

Question 29

viral reassortment

Question 30

infection types

Answer 30

1. acute- burst of rep before immune sys clears 2. chronic- burst of rep but immune reduces instead of clears after 3. latent- burst, immune sys stops in certain tissues, reactivates in other tissues

Question 31

syncytia formation

Answer 31

multinucleated cells from fusing together -infected + uninfected

Question 32

plaque assay

Answer 32

grow monolayer add sample look for plaques (1 virus infects and spreds to adj cells, little hole in monolayer) | quantitative for infectious agents

Question 33

antibodies

Answer 33

EISA westerna blot

Question 34

genomes

Answer 34

DNA, PCR RNA, RT-PCR

Question 35

viral antigesn

Answer 35

ELISA others