Lecture 1: introduction

Question 1

What is a virus?

Answer 1

a virus is a filterable, small obligate intracellular parasite that is inert outside of a host cell

Question 2

what does propagation of viruses depend on

Answer 2

specialized host cells that supply the metabolic and biosynthetic machinery of eukaryotic or prokaryotic cells

Question 3

T/F: viruses lack organelles

Answer 3

True. the only pseudo-exception to this is Arenavirus, which acquires ribosomes from the host cells. These ribosomes are not functional

Question 4

If you wanted to observe a virus, which of the following strategies could you use?
a) electron microscopy
b)nanoscopy
c) light microscopy
d) naked eye

Answer 4

Electron microscopy and/or nanoscopy

Question 5

What is the biggest virus, and what is the smallest?

Answer 5

pithovirus sibericum is the largest, at 1.5 micrometers.

Circovirus is the smallest at 17 nm

Question 6

what was the pasteur-chamberland filter?

Answer 6

A filter created in 1890 that allowed for bacteria and other cells to be removed from a lliquid. It worked by having pores of 100-1000 nm for filtering purposes

Question 7

What are the three structural components of a virus?

Answer 7

1. the genome
2. capsid coat made 100% of protein
3. +/- an envelope consisting of a lipid bilayer

Question 8

Describe viral envelop formation

Answer 8

modified host cell membranes surrounds the capsid.

Question 9

what is the viral envelop made of

Answer 9

lipid bilayer that is studded with virus-coded glycosylated membrane proteins

Question 10

what do budding viruses carry?

Answer 10

certain host cell proteins that form integral constituents of the viral envelope

Question 11

what is a bacteriophage?

Answer 11

a virus that infects bacteria. It consists of a head made from protein and DNA, and a tail of solely protein

Question 12

What virus is commonly used as a vector to deliver antigens?

Answer 12

poxvirus

Question 13

what is the largest animal virus?

Answer 13

poxviruses

Question 14

70% of all viruses are ___ viruses

Answer 14

RNA

Question 15

What are the two types of viral genomes?

Answer 15

Single-coil and fragmented

Question 16

what is the implication of having a segmented genome in a virus?

Answer 16

mispackaging and subtypes from replication of the fragments

Question 17

Give an example of a virus with a single-coil genome

Answer 17

Respiratory syncytial virus

Question 18

give an example of a virus with a fragmented genome

Answer 18

rotavirus

Question 19

Go review the central dogma if you’ve forgotten it

Answer 19

good stuff

Question 20

what was the first classification system for viruses

Answer 20

Linnaean hierarchical system

Question 21

What did the international committee on taxonomy of viruses (ICTV) deem was wrong with using the Linnaean system for viruses?

Answer 21

Viruses have small genomes and a high mutation rate, making it difficult to classify them beyond order. Because of this, viruses should not be classified on phylum or class

Question 22

how many orders of viruses have been established by the ICTV

Answer 22

7

Question 23

Of the 7 orders of viruses described by the ICTV, which are the 3 that you should know?

Answer 23

Caudovirales-tailed dsDNA bacteriophages

Ligamenvirales-linear, dsDNA archaean viruses

Tymovirales-monopartite (+) ssRNA viruses that infect plants

Question 24

What does the Baltimore classification base its classification system on

Answer 24

the mechanism of mRNA production

Question 25

Name the seven groups of viruses in Baltimore classification

Answer 25

1. dsDNA
2. ssDNA
3. dsRNA
4. (+) ssRNA
5. (-)ssRNA
6. ssRNA-RT
7. dsDNA-RT

Question 26

Pathogenesis of mRNA synthesis in dsDNA viruses (excepting pox)

Answer 26

dsDNA -> cellular RNA polymerase 2 -> mRNA (+)

Question 27

what is the only dsDNA virus that uses virion transcriptase as opposed to cellular RNA poly 2?

Answer 27

asfa, irido, and (most importantly) pox

Question 28

describe the pathway of mRNA synthesis for pox viruses

Answer 28

Pox dsDNA -> virion transcriptase -> mRNA (+)

Question 29

describe the pathway of mRNA synthesis in ssDNA

Answer 29

ssDNA->cellular DNA polymerase -> dsDNA -> cellular RNA polymerase 2 -> mRNA (+)

Question 30

what are some examples of dsDNA viruses

Answer 30

Adeno
Hepadna
Herpes
Papilloma
polyoma
Asfa
Irido
Pox

Question 31

what are some examples of ssDNA

Answer 31

Anello
Circo
parvo

Question 32

describe the pathway of primary mRNA synthesis by ssRNA (+) (excepting retroviruses)

Answer 32

the ssRNA (+) acts as the mRNA (+), and doesn’t have to undergo any transformation

Question 33

describe the pathway of mRNA synthesis by retroviruses (ssRNA (+))

Answer 33

retro -> virion reverse transcriptase -> ssDNA -> integrates with host genome -> cellular poly 2 -> mRNA (+)

Question 34

describe the pathway of mRNA synthesis by dsRNA

Answer 34

dsRNA -> virion RdRp -> mRNA (+)

Question 35

describe the pathway of mRNA by ssRNA (-) (excepting delta)

Answer 35

ssRNA (-) ->virion RdRp ->mRNA (+)

Question 36

pathway of mRNA by deltaviruses

Answer 36

Delta ->cellular RNA poly 2 -> mRNA (+)

Question 37

what are some examples of ssRNA (+)

Answer 37

picona
Flavi
calici
astro
corona
retro

Question 38

what are some examples of dsRNA viruses

Answer 38

reo
birna

Question 39

What are some examples of ssRNA (-) viruses

Answer 39

rabdo
filo
borna
paramyxo
orthomyxo
bunya
delta