6+7: DNA and RNA multiplication

Question 1

Parts of Eclipse:

Answer 1

• Early transcription, translateion: enzymes
• Replication: nucleid acid multiplication
• Late transcription, translation: structural proteins

Question 2

Classification of viral families:

Answer 2

- Baltimore system
I. dsDNA
II. ssDNA
III. dsRNa
IV. +ssRNA
V. -ssRNA
VI. viruses using transcriptase

Question 3

Properties of virus multiplication:

Answer 3

Use of cellular enzymes, ribosomes, nucleotides, amino acids and energy

Question 4

Properties of virus multiplication of DNA virus:

Answer 4

the NA is similar to the cellular genetic material

Question 5

Properties of virus multiplication of RNA virus:

Answer 5

RNA does not store information –> needs special enzyme for replication.

• RNA dependent RNA polymerase (RdRp)
• coded by the virus, sometimes carried in the virion
• mutations during replication

Question 6

Coding system of Cell and Virus:

Answer 6

Cell: monocistronic –> separate mRNAs for the proteins
Virus: lack of space - can be polycistronic

Question 7

Name some Double stranded DNA viruses:

Answer 7

Papilloma-, Polyoma-, Adeno-, Herpes-, Pox-, Asfarviridae

Question 8

What happens during Early Transcription in dsDNA viruses?

Answer 8

• the viral DNA enters into the nucleus
• cellular transcriptase: –> mRNA

Except: Pox-, Asfarviridae

• own viral transcriptase
• multiplication in the cytoplasm

Question 9

What happens during Early Translation in dsDNA viruses?

Answer 9

• on the surface of the ribosomes - cellular translation.

- non-structural protein synthesis

Question 10

What happens during Replication in dsDNA viruses?

Answer 10

• Viral replicase (better than the cellular, production in abundant amount)

Question 11

What happens during Late Transcription, Translation in dsDNA viruses?

Answer 11

• The progeny DNAs serve as template

- high amounts of structural protein synthesis

Question 12

Name som Single stranded DNA viruses:

Answer 12

Parvo-, Circoviridae (circular genome)

Question 13

What happens during Transcription of ssDNA viruses?

Answer 13

mRNA synthesis fro the coding tread

Question 14

What happens during Translation of ssDNA viruses?

Answer 14

• cellular translation

- polycistronic mRNA = enzymatic cleavage

Question 15

What happens during Replication of ssDNA viruses?

Answer 15

• small genome: no own polymerase
• Cellular polymerase copies the dsDNA
• eventually one tread is removed

Question 16

What is special about Autonomous Parvoviruses, Circoviridae?

Answer 16

• multiplication only in S-phase (dividing) cells

- pathology = enterocyte, embryo, bone marrow cells etc.

Question 17

What is special about Dependovirus?

Answer 17

use the replicase of adeno- or herpesviruses

Question 18

Name some dsRNA viruses?

Answer 18

Reo-, Birnaviridae

Question 19

What is special about Reo- and Birnaviridae?

Answer 19

dsRNA

• segmented genome (Reo-10:12; Birna-2)
• Alien NA for the cell: intensive interferon response, partial decapsidation

Question 20

What happens during Transcription of dsRNA viruses?

Answer 20

• the dsRNa is not readable for the ribosomes

- viral RdRp - structural: transcription mode = mRNA synthesis

Question 21

What happens during Translation of dsRNA viruses?

Answer 21

• monocistronic coding: segment - proteins

Question 22

What happens during Replication of dsRNA viruses?

Answer 22

• the mRNA enters into the inner capsid

- viral RdRp in replicase mode: the mRNA is supplemented with a negative thread

Question 23

What happens during Late Transcription, Translation of dsRNA viruses?

Answer 23

assembly of progeny virions

Question 24

Name some +ssRNA viruses?

Answer 24

Picorna-, Calici-, Toga-, Flavi-, Corona-, Arteri-, Astroviridae

Question 25

What happens during Transcription of +ssRNA?

Answer 25

- genomic RNA - mRNA - 5´ methyl capped, 3´ polyadenylated - directly attaches to the ribosomes

Question 26

What happens during Translation of +ssRNA?

Answer 26

Two different: Plycistronic mRNA and monocistronic mRNA

Question 27

What happens during Translation of +ssRNA in Polycistronic mRNA?

Answer 27

picornaviruses, flaviviruses - precursor polypeptide - protease cleavage - equimolar protein production

Question 28

What happens during Translation of +ssRNA in Monocistronic mRNA?

Answer 28

subgenomic mRNA synhtesis Nidovirales, Calci-, Togaviridae - for structural protein production - more accurate synthesis control

Question 29

What happens during Replication of +ssRNA?

Answer 29

- viral replicase (RdRp, non-structural) - replicative intermediate forms (RI): dsRNA, -ssRNA - the -ssRNA is template for the progeny +ssRNA genome - translation from the progeny RNA - finally the + threads incorporate into the progeny virions

Question 30

Name some -ssRNA viruses:

Answer 30

Orthomyxo-, Paramyxo-, Borna-, Filo-, Thabdo-, Arena-, Bunyaviridae

Question 31

What happens during Transcription of -ssRNA?

Answer 31

- negative sense RNA (3´-->5´) - not readable for the ribosomes --> viral RdRp- structural - transcription mode: complementary (+) thread synthesis --> mRNA - Arenaviridae, vertain Bunyaviruses: Ambisense genome

Question 32

What happens during Translation of -ssRNA?

Answer 32

monocistronic - Orthomyxo-, Arena-, Bunyav: segmented - Mononegavirales: short mRNAs

Question 33

What happens during Replication of -ssRNA?

Answer 33

``` the RdRp in replication mode: - dsRNA (RI) in the nucleocapsid - full length +ssRNA synthesis - -ssRNA synthesis finally the negative threads stay in the progeny virions ```

Question 34

Name some viruses using reverse transcriptase: RNA/DNA

Answer 34

Retroviridae

Question 35

What happens during Transcription of Viruses using reverse transcriptase: RNA/DNA?

Answer 35

Genome - mRNA, but: - reverse transcriptase (structural) - transcribes to dsDNA The viral dsDNA integrates into the cellular genome: - provirus - cell division - virus genome copying Transcription: - cellular transcriptase: mRNA production - long terminal repeat (LRT) regions: intensive promoter, frequent transcription

Question 36

What happens during Translation of Viruses using reverse transcriptase: RNA/DNA?

Answer 36

polycistronic mRNA - protease cleavage

Question 37

What happens during Replication of Viruses using reverse transcriptase: RNA/DNA?

Answer 37

= transcription! | - the mRNA will finally serve as the genome of the progeny viruses

Question 38

What are Hepadnaviridae?

Answer 38

ss/ds DNA (circular)

Question 39

What happens during Transcription of Hepadnaviridae?

Answer 39

- repair of the grapped genome: viral polymerase - cellular transcriptase: mRNA production - -> short transcripts - proteins

Question 40

What happens during Translation of Hepadnaviridae?

Answer 40

monocistronic mRNAs

Question 41

What happens during Replication of Hepadnaviridae?

Answer 41

- full length transcripts of "mRNA" (cellular enzyme) - maturation: viral reverse transcriptase produces complementary DNA thread - circularization, partly completed to dsDNA

Question 42

What are the importance of eclipse strategies?

Answer 42

- consequences on pathogenesis, epidemiology - detection of replicative intermediate forms - active virus mulitplication - in vitro protein expression studies - Anti-viral drug development.: inhibition of virus-specific enzymes ( like HIV!)