Virus-virus interaction

Question 1

Examples of a virus’ environment

Answer 1

• Another virus
• Host cell
• Host organism

Question 2

When does virus-virus interaction occur?

Answer 2

• During multiplication
• Simultaneous infection of the same cell
• Usually between related viruses

Question 3

Give the types of virus-virus interaction

Answer 3

• Advantageous
  
  • On NA level (recombination)
  • On protein level
• Disadvantageous (Interference)
• Neutral (Virusexaltation)

Question 4

Whose best?

Answer 4

Luke’s best

Cian Ryan is gay

Question 5

Recombination

Answer 5

Exchange of genetic information

• New virus generation - inherited new properties
• At least 20-40 nucleotide homology between the viruses is needed

Question 6

Intramolecular recombination

Answer 6

• Derailing of the polymerase during replication
• Aujeszky’s disease virus: 70% transfer
• Sometimes between non-related viruses
• Also with RNA viruses

Question 7

Genetic reassortment

Answer 7

• Viruses with a segmented genome
• Exchange of segments during viral assembly
• Sudden, major antigenic changes
  
  • Antigenic shift

Question 8

Reactivation

Answer 8

• Cross reactivation
  
  • Attenuated vaccine strain + related virus
  • Repair of the defected virulence-genes
  • i.e herpesvirus
• Multiple reactivation
  
  • Between two attenuated virus-strains
  • Different defected genomic regions
  • Mutual completion

Question 9

Two different live vaccines shouldn’t be used when?

Answer 9

Within a short time interval

Question 10

Complementation

Answer 10

• Between defective and competent (helper) viruses
• Exchange of enzymes (polymerase)
  
  • Multiplication of the defected virus
    
    • Heat sensitive-mutant + wild type virus
    • Avirulent virus + inactivated virulent virus
    • Dependovirus + adenovirus

Question 11

Phenotype mixing

Answer 11

• Exchange of structural proteins
• Leukosis + sarcoma virus: Acquiring envelope proteins
• Transcapsidation
• Non-heritable

Question 12

Interference

Answer 12

One virus inhibits the multiplication of the other:

• Adsorption interference
• Autointerference
• Heterologous interference

Question 13

Adsorption interference

Answer 13

• Competition for the same cell-surface receptor
  
  • Related viruses or
  • After phenotype mixing or
  • Different viruses but the same receptor

Question 14

Autointerference

Answer 14

• Complete and incomplete forms of the same virus
• Also at adsorption
• Incomplete virion:
  
  • Shorter nucleic acid
  • Higher mobility, polymerase affinity
• Competition for enzymes, ribosomes
  
  • Defective interfering particles (DI)
• Large amounts of incomplete progeny viruses
  
  • Self-limiting infections

Question 15

Heterologous interference

Answer 15

• Non-related viruses
• Vital suppressor protein production

Question 16

Virusexaltation

Answer 16

• Viruses are able to multiplicate independently
• Simultaneous infection doesn’t affect the multiplication

But

It changes the viral influence on the host cell or organism:

• Increased pathogenicity
• Cytopathic effect appears