Lecture 3

Question 1

Common naming system for animal viruses

3

Answer 1

1. Diseases that they cause
2. Places where virus was first identified
3. Other

Question 2

Common naming system for plant viruses

Answer 2

1. Host
2. Disease

Question 3

Properties of viruses that should be the basis for classification

Answer 3

1. Disease symptoms
2. Host organisms
3. Physical structure of the virus particle

Question 4

Problem with traditional name classification

Answer 4

Too many distinct entities

Question 5

Committee that classifies viruses into specific orders, families, genus, and species

Answer 5

International Committee on Taxonomy of Viruses

Question 6

Taxonomy Scheme

Answer 6

Order, Family, Subfamily, Genus, Species

Question 6

Baltimore Classification System

Answer 6

-System used to categorize viruses based on their genomic structure and the mechanism they use to replicate within a host cell

Question 7

Hierarchical virus classification system

4 components

Answer 7

1. Nature of the nucleic: DNA or RNA
2. Symmetry of the capsid
3. Presence or absence of an envelope
4. Dimensions of the virion and capsid

Question 7

Family in taxonomy scheme

Answer 7

A group of genera with common characteristics

Question 8

Species in taxonomy scheme

Answer 8

A cluster of strains that have in common a set pattern of stable properties

Question 8

Origins of family names

4

Answer 8

1. Symptoms of disease caused by viruses
2. Sites of infection
3. Physical characteristics of the viruses
4. Combination

Question 8

Subfamily in taxonomy scheme

Answer 8

Groups within some large families

Question 9

Order in Taxonomy Scheme

Answer 9

Group of families with a common characteristic

Question 10

Genus in taxonomy scheme

Answer 10

A group of virus species sharing common chracteristics

Question 10

Further breakdowns not recognized by the ICTV

Answer 10

Group, Strain, Varient

Question 11

Group

Answer 11

Sub-category of species, division often based on genomic sequence similarities or origin

Question 12

Defective Interfering (DI) Particle

Answer 12

A virus that lacks part of its genome, is unable to replicate by itself and interferes with the replication of a standard virus

Question 12

Strain

Answer 12

Different lines of isolates of the same virus

Question 12

Varient

Answer 12

Virus whose phenotype differs from original wild type strain but where the genetic basis for the difference is not known

Question 13

Common features of satellite viruses and satellite nucleic acids

5

Answer 13

1. Does not encodes enzymes required for replication
2. Require co-infection with a conventional (Helper) virus
   3.Satellite genome is significantly different from the helper virus
   4.May affect replication of the helper virus
   5.. May increase or decrease severity of disease

Question 13

Requirement of DI particles

4

Answer 13

1. Require helper virus
2. Derived from that helper virus
3. Product of polymerase “Leaping”
4. Interferes with helper virus replication

Question 14

Viroids

Answer 14

Novel agent of disease in plants. Single circular ssRNA molecule with no protein components

Question 14

Satellite viruses

2

Answer 14

-Encodes structural proteins that form the viral capsid
-They rely on the helper virus replicative machinery to replicate their genome

Question 15

Satellite nucleic acids

Answer 15

Similar to satellite viruses except they don’t make their own capsid. They encode only nonstructural proteins or none at all. Rely on a helper virus for replication and capsid formation

Question 16

How coronaviruses maintain genomic integrity with high error rate of RNA polymerases

Answer 16

Proof-reading 3 to 5 exoribonuclease