Lecture 2 Flashcards

1
Q

What are the steps in viral replication (6)

A
  1. Attachment
  2. Penetration
  3. Uncoating
  4. Replication of viral proteins and nucleic acid - eclipse phase
  5. Assembly of the viral proteins and packaging of the nucleic acids
  6. Release of virions
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2
Q

What is attachment

A

Ligands/receptors sites on the surface on the surface of the visions bind to receptors on the cell surface

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3
Q

How is the initial binding of attachment done

A

Electrostatic forces

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4
Q

How does attachment occur

A

when there is a specific affinity exists between the cell and the virus

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5
Q

What determines TROPISM of viruses

A

Presence or absence of sites

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6
Q

How does a reversible bond work

A

A loose contact between cell membrane and virus which depend upon the maintenance of the electrostatic forces produced by the concentration of electrolytes

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7
Q

What is the reversible bond dependent on

A

Temperature

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8
Q

How does the irreversible bond work

A

Late stage of the process which become temperature dependent. The virus is now protected from antibodies

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9
Q

What are the 2 mechanisms of penetration

A
  1. Endocytosis

2. Fusion

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10
Q

How is the process of uncoating brought about

A

Lysosomes

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11
Q

How does the Eclipse phase occur

A
  1. DNA is transcribed to viral mRNA which is translated to viral proteins
  2. The gnome of positive strand RNA viruses may function as a mRNA
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12
Q

What type of proteins make up a virion

A

Structural protein

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13
Q

What functions do non-structural proteins have

A

Protease and transcriptase activity or transport of other proteins

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14
Q

Where is viral DNA transcribed

A

Nucleus

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15
Q

How are helical capsids assembled

A

Helical capsids usually assemble around strands of nucleic acids

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16
Q

How are icosahedral capsids assembled

A

as empty sheets and filled with nucleic acids

17
Q

How are complex viruses assembled

A

progressively assembled to form the complete virion

18
Q

How are DNA viruses assembled

A

in the nucleus

19
Q

How are RNA viruses assembled

A

in the cytoplasm

20
Q

How are naked viruses released

21
Q

How are enveloped viruses released

A

Bud through host membranes

22
Q

What do most viruses inhibit

A

Protein synthesis

23
Q

How can Eukaryotic host translation be inhibited (3)

A
  1. Inhibition of host cell mRNA from the nucleus
  2. Differential degradation of host cell mRNA
  3. Blockage of host cell mRNA
24
Q

What can picornaviruses shut down

A

Host ribosome translation

25
What does the eclipse phase mean
Disappearing phase
26
Can you see the virus in the eclipse phase
No, it is where transcription and translation is occurring
27
What is syncytial formation
Fusion of cell membranes - giant cel formation
28
What are inclusion bodies
Dark areas with a halo around it