Virus Genome Diversity

Question 1

What is the largest virus called?

Answer 1

Mimivirus

Question 2

What is error-catastrophe?

Answer 2

Too many mutants within the viral genome, it is too far from the optimum so the virus self-destructs.

Question 3

What two subcategories can single-stranded RNA genomes be split into?

Answer 3

Positive and Negative sense

Question 4

What is the purpose of the 5’cap?

Answer 4

Resistance to exonucleases and recognition by translational machinery.

Question 5

When can positive sense RNA be translated?

Answer 5

Immediately, RNA has a very short half-life

Question 6

What structures do positive-sense RNA viruses have?

Answer 6

5’cap (m7G)and a polyA tail to mimic the host’s mRNA

Question 7

What initiates cap binding?

Answer 7

eIF4A - RNA can cap snatch

Question 8

What is the IRES?

Answer 8

Internal ribosome binding entry site, the genome can H-bond to itself making secondary structures that mimic the cap

Question 9

Name 5 +sense RNA viruses

Answer 9

1. Flavivirus
2. HepC
3. Picornavirus
4. Alphavirus
5. Coronavirus

Question 10

Give 3 examples of the Flavivirus

Answer 10

1. Dengue fever
2. Yellow Fever
3. West Nile

Question 11

How is HepC different to Flavivirus?

Answer 11

Has an IRES site instead of an m7G cap

Question 12

Give 4 examples of picornavirus

Answer 12

1. Polio
2. Rhinovirus
3. HepA
4. FMDV

Question 13

How many open reading frames does alpha virus have?

Answer 13

2

Question 14

Give 2 examples of coronavirus

Answer 14

1. SARS

2. MERS

Question 15

What are the features of a retrovirus?

Answer 15

Single-stranded
Positive sense RNA
5'-cap and a 3'-polyA tail
Integrates into host cell genome
Multiple and overlapping ORFs

Question 16

What are the two subgroups of negative sense RNA viruses?

Answer 16

Segmented and non-segmented

Question 17

Give 3 -sense RNA viruses

Answer 17

1. Rhabdovirus
2. Filovirus
3. Orthomyxovirus

Question 18

Two examples of rhabdovirus

Answer 18

1. Rabies

2. Vesicular stomatitis

Question 19

2 examples of filovirus

Answer 19

1. Ebola

2. Marburg

Question 20

1 example of orthomyxovirus

Answer 20

Influenza

Question 21

Give 3 DNA viruses

Answer 21

1. Adenovirus
2. Herpesvirus
3. Papillomavirus

Question 22

What is an inverted terminal repeat?

Answer 22

A single stranded sequence of nucleotide followed downstream by its reverse compliment

Question 23

Is the papillomavirus genome linear or circular?

Answer 23

Small circular

Question 24

What charge do capsid proteins have and rich in what amino acids?

Answer 24

Positively charged and rich in arginine and leucine

Question 25

What are glycoproteins for?

Answer 25

Recognition of host cell receptors (setting the tropism)

Question 26

When are matrix proteins present?

Answer 26

In enveloped viruses, interact with both capsid and envelope proteins

Question 27

What is the tegument?

Answer 27

A cluster of proteins which line the space between the envelope and nucleocapsid of herpesvirus

Question 28

What do lipid envelopes contain?

Answer 28

Glycosylated proteins which can recognise specific receptors.

Question 29

What is maturation of viral glycoproteins for?

Answer 29

Avoiding tangling

Question 30

What directions are polyproteins cleaved in?

Answer 30

Cis and Trans