39 - Bacteriophages

Question 1

Bacteriophages

Answer 1

• Etymologi: phagos: eating
• Morphology:
  
  • ​High diversity
  • Groups: A-G
    
    • Nucleic acids:
      
      • dsDNA
      • ssDNA
      • dsRNA
      • ssRNA
    • Symmetry:
      
      • Binal
      • Icosahedral
      • Helical
      • Pleomorphic
• Biological properties: bacteria has no immunesystem, so antigenic features are less important
• ​Penetration: needs special routs to penetrate
• Species specificity:
  
  • Phage typing: used to identify a bacterial species, if phage increases then that bacteria is present
  • Phage titer increase: detects salmonella typhi in drinking water. Detects with M3 phage, if phage increases then the salmonella is present
    
    • A reliable identify method for bacteria
• Lysogen infection: temperate phage (prophage)
• Lysogen conversion: changed bacterial properties
• Transduction: gene transfer between bacteria
• Lytic effect on bacteria:
  
  • ​→ potential antibacterial treatment of infected vertebrate hosts, if antibiotics are not applicable
    
    • Problems with the application (antigens)
    • Promising experimental results

Question 2

Bacteriophages

List some important phages

Answer 2

• Tbilissi:
  
  • ​Tb phage – Brucella typing
• T4 phage
  
  • E-coli
  • Big
  • Complicated phage
• •β phage
  
  • Diphtheria
• λ phage
  
  • ​E-coli
  • Gene sequence are known, and used as a molecular marker
• •φX174 phage
  
  • E-coli
  • The smallest known virus (12 nm)

Question 3

Bacteriophages

How does resistance occure?

Answer 3

Increased used antibiotics ➔ resistance of bacteria ➔ need another form of treatment➔ increased use of bacteria phages

Question 4

Bacteriophage

What is a bacteriophage?

Answer 4

• A bacteriophage is a virus that infects bacteria
• Phage genomes can consist of either RNA or DNA
  
  • Can contain 4 to several hundred genes
• Bacteriophages must infect a host cell in order to reproduce
• Found where bacteria exist
• Before antibiotics was discovered, there was research on bacteriophages as a treatment for human bacterial diseases.
• Bacteriophages attack only their host bacteria, not human cells, so they are potentially good candidates to treat bacterial diseases in humans (used in Russia and Central-Europe)
• Can be an option due to the antibiotic-resistant issue in the future