Virology Introduction Handout (1st Two Ppts)

Question 1

3 reasons why viruses are beneficial

Answer 1

• biodiversity: transmit genetic material from one host to another
• residual immunity: post-infection, host can become immune to more virulent viruses
• some viruses eliminate harmful bacteria

Question 2

Properties of viruses

Answer 2

• obligate intracellular organisms
• lack organelles (i.e. mitochondria, golgi complex, ER, ribosomes)
• use host cell’s nucleus to replicate
• lack metabolic capabilities (i.e. protein synth & energy prod)
• diameter range is 20 nm to 250 nm

Question 3

Eclipse Period

Answer 3

• period where virus can’t be detected by standard testing
• is time between entry of virus into cell and production of new virus particles

Question 4

Smallest animal virus

Answer 4

Parvo

Question 5

Largest animal virus

Answer 5

Pox

Question 6

Nucleocapsid

Answer 6

• nucleic acid genome w/ protein coat
• can come in icosahedral, helical, or complex symmetry shapes

Question 7

All animal viruses contain what 2 items?

Answer 7

• DNA or RNA
• nucleocapsid (protein coat)

Question 8

Icosahedral shape

Answer 8

• pentagon w/ 20 facets

Question 9

Naked viruses

Answer 9

Lack an envelope

Question 10

Which virus only has a nucleocapsid

Answer 10

Adenovirus

Question 11

Which 2 viruses have a nucleocapsid and envelope

Answer 11

Flavivirus & paramyxovirus

Question 12

Virus

Answer 12

A general description of virus BEFORE it infects cell

Question 13

Virion

Answer 13

Mature infectious virus

Question 14

Viroid

Answer 14

Term used for plants

Question 15

Complete virion

Answer 15

• infectious and binds specifically to host cells
• ex. Poliovrus

Question 16

Virus symmetry

Answer 16

• recombinant attenuated virus gene sequence is inserted in capsid proteins -> makes recombinant virus a good candidate for blocking attachment of infectious virus

Question 17

What is the relationship between viral symmetry and infectiousness

Answer 17

They are independent of each other

Question 18

What 2 methods are used to determine viral taxonomy?

Answer 18

• PCR
• Negative staining EM

Question 19

PCR Testing

Answer 19

• amplification & sequencing of nucleic acids
• determines if DNA/RNA, family, density

Question 20

Negative staining EM

Answer 20

• Viruses are imbedded in electron dense dye & examined via EM
• Used to ID shape and size of viruses & can assign unknown viruses to a family

Question 21

9 taxonomic groups of viruses

Answer 21

• viral morphology
• nucleic acid morphology
• host they infect
• vector (if insect)
• location of viral replication (cytoplasm, nuclear, organelles)
• enveloped vs non-enveloped
• capsid symmetry

Question 22

Hierarchy of viral taxa

Answer 22

• order
• family
• subfamily
• genus
• species