Lecture 11 Part 4

Question 1

Subviral entities are

Answer 1

infectious agents that resemble viruses

Question 2

Subviral entities examples

Answer 2

defective viruses, viroids, and prions

Question 3

defective viruses

Answer 3

cannot infect host cell alone
- rely on helper viruses that can be the same type of virus or completely unrelated

Question 4

defective viruses example

Answer 4

bacteriophage P4
- genome does not encode capsid proteins
- relies on phage P2 to provide capsids

Question 5

Satellite virus

Answer 5

• no full functional virus exits
• rely on completely unrelated helper viruses

Question 6

satellite virus example

Answer 6

adeno-associated virus
- plant and animal virus
- cannot replicate without helper adenovirus
- used in gene therapy

Question 7

viroids

Answer 7

infectious RNA molecules
- no capsid and no protein-encoding genes
- found only in plants
- high degree of secondary structure (prevents degradation)
- enters host cells through wounds

Question 8

Prions

Answer 8

infectious protein molecules
- no DNA/RNA
- misfolded proteins
- found in animals (including humans)

Question 9

prions example

Answer 9

BSE or Mad Cow Disease
- transmitted animal to animal and animal to human through consumption of infected beef

Question 10

Native prion proteins (PrPc)

Answer 10

• present in neurons of healthy animals

Question 11

misfolded prion proteins (PrPsc)

Answer 11

• present in diseased animals
• same amino acid sequence as PrPc, different structural conformation

Question 12

Effects of misfolded confirmation prions

Answer 12

• resistant to proteases (degradation)
• becomes insoluble (aggregates in neurons)
• induced misfolding of native proteins (“replication”)