DNA multiplication

Question 1

Eclipse

Answer 1

The central step of virus multiplication

• From first mRNA → First virion assembly

Question 2

Give the steps of the eclipse

Answer 2

1. Early transcription, translation: Enzymes
2. Replication: NA multiplication
3. Late transcription, translation: Structural proteins

Question 3

Multiplication of viral NA is dependent on…

Answer 3

The host cell

Question 4

The Baltimore system

Answer 4

Classification of viral families according to their NA/multiplication strategy

Question 5

Give the classifications of the Baltimore system

Answer 5

1. dsDNA
2. ssDNA
3. dsRNA
4. +ssRNA
5. -ssRNA
6. Viruses using reverse transcriptase

Question 6

Properties of virus multiplication: DNA virus

Answer 6

Nucleic acid similar to cellular genetic material

Question 7

Properties of virus multiplication: RNA virus

Answer 7

In the cell, RNA doesn’t store information

• Enzyme needed for replication
  
  • RNA dependent RNA polymerase (RdRp)
• Mutations during replication - Quick evolution

Question 8

Properties of virus multiplication:Coding system

Answer 8

• Monocistronic cell → Separate mRNAs for the proteins
• Virus: Lack of space: Can be polycistronic

Question 9

Steps of transcription, translation + NA replication: Double-stranded DNA viruses (dsDNA)

Answer 9

1. Early transcription
2. Early translation
3. Replication
4. Late transcription, translation

Question 10

Double-stranded DNA viruses (dsDNA): Early transcription

Answer 10

• Viral DNA enters nucleus
• Cellular transcriptase → mRNA

Question 11

Which dsDNA viruses don’t use cellular transcriptase?

Answer 11

• Poxvirus
• Asfarviridae family

They use their own viral transcriptase

Multiplication in the cytoplasm

Question 12

Double-stranded DNA viruses (dsDNA): Early translation

Answer 12

• On the surface of ribosomes → Cellular translation
• Non-structural protein synthesis

Question 13

Double-stranded DNA viruses (dsDNA): Replication

Answer 13

• Viral replicase
  
  • Better than cellular
  • High productivity

Question 14

Double-stranded DNA viruses (dsDNA): Late transcription, translation

Answer 14

• Progeny DNA serves as a template
• High structural protein synthesis

Question 15

Steps of transcription, translation + NA replication: Single-stranded DNA viruses (ssDNA)

Answer 15

1. Transcription
2. Translation
3. Replication

Question 16

Single-stranded DNA viruses form…

Answer 16

Self-priming hairpins

• Cellular polymerase synthesises complimentary thread

Question 17

Single-stranded DNA viruses (ssDNA): Transcription

Answer 17

mRNA synthesis from the coding thread

Question 18

Single-stranded DNA viruses (ssDNA): Translation

Answer 18

Cellular translation

• Polycistronic mRNA: Enzymatic cleavage

Question 19

Single-stranded DNA viruses (ssDNA): Replication

Answer 19

• Small genome: No own polymerase
• Cellular polymerase copies dsDNA
• Own thread is eventually removed

Question 20

Single-stranded DNA virus (ssDNA) examples

Answer 20

• Parvovirus
• Circoviridae family

Question 21

Multiplication of viruses with a circular genome

e.g Parvovirus

Answer 21

• Multiplication only in S-phase (dividing) cells
  
  • In enterocytes, embryo, bone marrow cells

Question 22

Dependovirus multiplication

Answer 22

• Uses the replicase of adeno- or herpesviruses