DD- VIRUS STRUCTURE ANDFX

Question 1

Koch’s postulates viral pitfall

Answer 1

The agent must be isolated from the host and grown in vitro- viruses cannot always do this

Question 2

The agent must be present in every case of the disease

The agent must be isolated from the host and grown in vitro.

The disease must be reproduced when a pure culture of the agent is inoculated into a healthy susceptible host.

The same agent must be recovered once again from the experimentally infected host.

Answer 2

Koch’s postulates

Question 3

A virus is a submicroscopic, infectious,______ intracellular parasite

Answer 3

obligate

Question 4

The genetic material of a virus enters a host cell and directs the production of the:

Answer 4

building blocks of new virus particles

Question 5

The genetic material of a virus is either _____ and is encased in a protein shell

Answer 5

DNA or RNA

Question 6

New virions are produced from self-assembly of______ components within the host cell

Answer 6

newly synthesized

Question 7

The new virions produced in a host cell ______ to another host cell or organism to carry out another round of infection

Answer 7

transport the viral genetic material

Question 8

Viruses house their DNA or RNA genomes in:

Answer 8

small proteinaceous particles (capsids).

Question 9

The viral genome contains all the information to______an infectious cycle.

Answer 9

initiate and complete

Question 10

Viruses establish a relationship that ranges from ____ in a population of hosts

Answer 10

benign to lethal

Question 11

2 Classification of viruses

Answer 11

The classical system: Linnaean/biological categorization of viruses governed by the ICTV

The Baltimore classification scheme

Question 12

The classical system:

Viruses grouped according to their shared physical properties (4)

Answer 12

a) Nature of the genetic material in the virion (DNA or RNA)
b) Symmetry of the capsid (helical or icosahedral)
c) Naked or enveloped
d) Dimensions of the virion and capsid

Question 13

dsDNA
Gapped circular DNA
ssDNA
dsRNA
ss(+)RNA
ss(+)RNA with DNA intermediate
ss(-)RNA

Answer 13

Seven Classes of Viral Genomes

Question 14

The Baltimore classification scheme

Answer 14

Based on the Central Dogma:

 DNA --> RNA -->protein

Question 15

a) Nature of the genetic material in the virion (DNA or RNA)
b) Symmetry of the capsid (helical or icosahedral)
c) Naked or enveloped
d) Dimensions of the virion and capsid

Answer 15

The classical system: Linnaean/biological categorization of viruses governed by the ICTV

Question 16

Seven Classes of Viral Genomes

Answer 16

dsDNA
Gapped circular DNA
ssDNA
dsRNA
ss(+)RNA
ss(+)RNA with DNA intermediate
ss(-)RNA

Question 17

_____protect the genome and serve as a specific genome delivery device

Answer 17

Capsids

Question 18

Nucleocapsid

Answer 18

Nucleic acid-protein complex in a virion when this is a substructure of a complex particle

Question 19

Envelope

Answer 19

Host cell-derived lipid bilayer

Question 20

Capsids assemble from components ______made during infection

Answer 20

(capsid proteins)

Question 21

Spike

Answer 21

Virus derived membrane-bound glycoproteins

Question 22

Viruses have evolved two general forms for packaging their genomes

Answer 22

Helical Capsids
Icosahedral Capsids

Both kinds can be surrounded by a lipid envelope

Question 23

Virion

Answer 23

Infectious virus particle

Question 24

virally encoded glycoproteins (spikes) function in

Answer 24

• entry and host range determinants
• assembly and egress
• evasion from the vertebrate immune system

Question 25

During the eclipse to latent period there is a lot going on inside of the cell (5)

Answer 25

Entry

Viral gene expression

Translation of viral proteins

Virus genome replication

Assembly of new viruses and release of virus from the cell

Question 26

A______ cell has a functional receptor for a given virus–the cell may or may not be able to complete the replication cycle

Answer 26

susceptible

Question 27

A _______cell has no receptor–it may or may not be competent otherwise to replicate the virus.

Answer 27

resistant

Question 28

A_______ cell has the capacity to replicate virus–it may or may not be susceptible

Answer 28

permissive

Question 29

A _________ cell is the only cell that can take up virus and replicate it

Answer 29

susceptible AND permissive

Question 30

Virus attachment to the cell surface

At least two steps are involved:

Answer 30

1. Non-specific, electrostatic binding places viruses in close proximity to cell surface.
2. Proteins on the virus particle must interact with proteins on the cell membrane to initiate the entry process.

Question 31

gain access into different tissue types

entry of virus into a single cell: co-receptors.

combination of carbohydrate and protein receptor molecules

these are examples of:

Answer 31

viruses use more than one receptor