Lecture 1.1 1/23/24

Question 1

What determines the size and shape of a virus?

Answer 1

-nucleic acid content
-amount of proteins
-arrangement of proteins

Question 2

What does virus structure have an impact on?

Answer 2

-cell type(s) the virus can enter
-environment the virus can survive in
-ability for virus to survive outside host
-viral life cycle

Question 3

What is a virus?

Answer 3

infectious particle that parasitizes off a host cell by using its machinery to produce more viruses

Question 4

What is a virion?

Answer 4

a complete virus particle outside the host cell consisting of DNA/RNA genome and a protein coat

Question 5

What is a capsid?

Answer 5

protein shell that encapsidates viral genomic material

Question 6

What is a nucleocapsid?

Answer 6

viral nucleic acid + capsid

Question 7

What are capsomeres?

Answer 7

small protein subunits that make up the capsid

Question 8

What encodes for the capsid proteins?

Answer 8

the viral genome, ALWAYS

Question 9

Where can attachment proteins for viral entry be found?

Answer 9

on the capsid or on the envelope

Question 10

What are the three main virus structures?

Answer 10

-icosahedral
-helical
-complex

Question 11

What is an icosahedral structure?

Answer 11

polyhedral capsids with multiple flat sides forming a rigid shell

Question 12

What is a helical structure?

Answer 12

wrap of proteins around the nucleic acid strand

Question 13

What is a complex structure?

Answer 13

structure that is neither entirely helical nor icosahedral, and is often pleomorphic

Question 14

What is a spherical form?

Answer 14

formation that can arise when helical nucleocapsids are enveloped

Question 15

What are the two types of icosahedral structure?

Answer 15

-simple
-complex

Question 16

What is an example of a simple icosahedral virus?

Answer 16

poliovirus

Question 17

What is an example of a complex icosahedral virus?

Answer 17

adenovirus

Question 18

What are the characteristics of helical structure?

Answer 18

-simplest arrangement of capsomeres
-lowest free energy

Question 19

What is an example of a complex virus?

Answer 19

poxvirus

Question 20

What are naked viruses?

Answer 20

viruses without a lipid envelope

Question 21

What are enveloped viruses?

Answer 21

viruses with a lipid envelope

Question 22

How do enveloped viruses acquire their envelope?

Answer 22

-obtained from lipid bilayer in the host cell
-plasma membrane, endosomal membrane, or ER/Golgi membrane

Question 23

What are glycoproteins?

Answer 23

viral proteins on the envelope that are required for infection

Question 24

What are the characteristics of naked viruses?

Answer 24

-environmentally stable to temp, acids, proteases, detergents, and drying
-easily transmitted
-can retain infectivity when dried out
-can survive adverse conditions
-resistant to most treatments other than bleach

Question 25

What is an example of naked viruses?

Answer 25

parvoviruses

Question 26

What are the characteristics of enveloped viruses?

Answer 26

-environmentally labile to temp, acids, detergents, and drying
-must stay wet in environment
-spread through droplets, secretions, and organ transplants/blood transfusions
-do not survive on external surfaces
-do not survive in GI tract

Question 27

What is the benefit of a viral envelope?

Answer 27

-allows for increased antigen variability and evasive capacity
-requires host to produce both antibody and cell-mediated immune responses