Final; Virus Biology

Question 1

What are the two theories of virus origin

Answer 1

cellular origin

autopoietic origin

Question 2

This proposes that viruses were once cellular components but over time they evolved separately

Answer 2

cellular origin

Question 3

This proposes that viruses, once autopoietic entities, became dependent on cells for replication

Answer 3

autopoietic origin

Question 4

What are the attributes that viruses are classified on

Answer 4

particle structure
genome
replication features
serology
stability

Question 5

What are the components of virus particle structure

Answer 5

composition
stucture
size

Question 6

This is RNA or DNA in a core that is protected by a protein coat

Answer 6

nucleocapsid

Question 7

A virus is defined by what

Answer 7

the nucleocapsid structure

Question 8

What are the different nucleocapsid structures

Answer 8

helical
pleomorphic
icosahedral

Question 9

A nucleocapsid is comprised of what

Answer 9

repeating protein subunits called capsomeres

Question 10

This is a virus-modified cellular membrane acquired upon exit from the host

Answer 10

envelopes

Question 11

This renders enveloped viruses noninfectious

Answer 11

exposure to lipid solvents in the laboratory

Question 12

True or False

Enveloped viruses may have nucleocapsids with different structures

Answer 12

True

Question 13

What are the lengths of the smallest and largest virus particle

Answer 13

smallest; 18nm

largest; 300nm

Question 14

What are the different combinations of the viral genome

Answer 14

double or single stranded

DNA or RNA

Question 15

What different types of single stranded RNA can you have

Answer 15

plus sense ssRNA
minus sense ssRNA
ambisense

Question 16

Which type of ssRNA can be used directly for translation

Answer 16

plus sense

Question 17

What must happen to minus sense ssRNA before translation

Answer 17

a positive (plus sense) copy must be made

Question 18

What are the different structures (gene arrangement) of the viral genome

Answer 18

linear
circular
segmented
diploid

Question 19

How can viruses not follow the central dogma

Answer 19

They are able to revert from RNA to DNA via reverse transcriptase

Question 20

What do most DNA viruses need that RNA viruses do not

Answer 20

access to the nucleus

Question 21

What do RNA viruses need that DNA viruses do not

Answer 21

the ability to make positive/negative strands

reverse transcriptase

Question 22

What is the process of viral replication

Answer 22

attachment
entry
transcription
translation
replication
assembly
release

Question 23

How does a virus attach to a cell

Answer 23

via receptors

the cell does not have viral receptors, the virus binds to already functional receptors on the cell

Question 24

What type of cell receptors do viruses bind to

Answer 24

signaling
cell adhesion
transport

Question 25

How to viruses attach to the cell receptors

Answer 25

do not mimic cell receptor ligands typically spike like projections may require co-receptor

Question 26

This is a major determinant of virus tropism (host range)

Answer 26

attachment

Question 27

True or False | Viruses are only specific to humans

Answer 27

False; viruses are known to infect essentially all forms of life

Question 28

This is a major factor in eradication

Answer 28

host range

Question 29

What are the pathways of viral entry

Answer 29

receptor mediated endocytosis | direct penetration of plasma membrane

Question 30

How can non-enveloped viruses entry the cell

Answer 30

its not well understood | perhaps through pores or membrane disruption

Question 31

In what ways can enveloped viruses enter the cell

Answer 31

membrane fusion | receptor conformational change (pH; receptor induced)

Question 32

How does nuclear replication occur

Answer 32

the genome and remaining protein coat are transported to the nucleus to deliver the genome

Question 33

How does cytoplasmic replication occur

Answer 33

genome is released into cytoplasm to site of replication | many RNA viruses replicate in MACs

Question 34

dsRNA viruses never release what

Answer 34

their genomic material from the entering particle

Question 35

DNA viruses rely on what for transcription

Answer 35

cellular RNA polymerases

Question 36

The genome of what can serve was mRNA

Answer 36

+ssRNA

Question 37

These RNA viruses must bring their own polymerases into the cell

Answer 37

-ssRNA | dsRNA

Question 38

All viruses need what to produce proteins

Answer 38

the cells ribosomes

Question 39

Non-structural proteins are only seen where

Answer 39

inside the infected cell

Question 40

The order of genomic replication of viruses depends on what

Answer 40

virus genome

Question 41

This induces innate immune response so the genome stays inside the particle

Answer 41

dsRNA

Question 42

The dsRNA mRNA is synthesized where

Answer 42

inside the particle and is then transported to the cytoplasm

Question 43

Why are poxviruses an exception to the DNA viruses needing access to the nucleus

Answer 43

virion contains the necessary RNA polymerase and the genome encodes the DNA polymerase for replication

Question 44

What is the function of viral assembly

Answer 44

to package new genomes into functional particles

Question 45

What aids in assembly

Answer 45

localized structural proteins; cellular viral "factories" | the genome contains packaging signals

Question 46

How does an adenovirus undergo assembly

Answer 46

empty protein coat imports genome

Question 47

How does a reovirus undergo assembly

Answer 47

RNA packaged during capsid assembly

Question 48

How does a retrovirus undergo assembly

Answer 48

reassembly on a membrane

Question 49

What are the different types of viral releases

Answer 49

lysis weak lysis (impair membrane repair) budding (enveloped only)

Question 50

What are the kinetic phases of viral replication

Answer 50

eclipse; attachment and uptake exponential growth; replication and assembly plateau; cell death

Question 51

True or False There is a variety of the length of time it takes for a virus to go from the start on an infection to the beginning of a plateau

Answer 51

True; bacteriophage; 30 mins vaccina; 24 hours

Question 52

What is the productivity of a virus

Answer 52

measure amplification vesicular stomatitis virus (VSV) 1:1000 vaccina 1:100

Question 53

What methods are used to initially discover a virus

Answer 53

disease in host | contaminant in cell culture

Question 54

What methods are used to confirm a virus

Answer 54

purification | confirmation of disease; animals, eggs, or cell culture (preferred)

Question 55

What are the principle of detection and quantification methods

Answer 55

infectivity physical genome serological

Question 56

These methods are useful for viruses that cannot be cultivated

Answer 56

molecular methods

Question 57

What are four types of infection assays

Answer 57

cytopathic effect (CPE) fluorescent focus assay plaque assay Infectious dose

Question 58

What are two types of particle assays

Answer 58

electron microscopy | hemagglutinin assau

Question 59

What are two types of genome assays

Answer 59

PCR | southern (DNA) and northern (RNA) blots

Question 60

What are three types of serological assays

Answer 60

virus neutralization enzyme linked immunosorbant assay (ELISA) western (protein) blot

Question 61

True or False | Different methods of viral detection and quantification give different answers

Answer 61

True

Question 62

What is the average diameter of a human virus

Answer 62

30-300nm