8 Bacteriophages and Endolysins

Question 1

Define a bacteriophage.

Answer 1

Viruses which infect bacteria

Question 2

What sort of diseases are bacteriophages used against?

Answer 2

Dysentery (shingellosis) and staphylococcal skin infections

Question 3

What are the most common kinds of T phage?

Answer 3

T4 and T7

Question 4

Do phages have specific or nonspecific modes of action?

Answer 4

Highly specific

Question 5

What is the main issue of phage therapy? And what would treatment require?

Answer 5

They target a very narrow range of organisms

Treatment would require prior information about organism

Question 6

What happens when phage therapy enters lysogenic phase?

Answer 6

Potential to introduce enhanced bacterial virulence or antibiotic resistance

Question 7

What must the phage used in medication be?

Answer 7

Must be pure which makes formulation problematic

Question 8

Phages can be distributed around they body, which means that what could happen?

Answer 8

They may trigger an immune response which may be inactivated by hosts antibodies

Question 9

The systemic release of endotoxin may potentially develop what?

Answer 9

Septic shock

Question 10

What does the phage product that is used for antimicrobial application in the US food and drug industry contain?

Answer 10

6 specific phages specific for Listera monocytogenes

The product can be applied as a spray for raw meats and is used to protect against listeriosis

Question 11

Describe the phage life cycle

Answer 11

Lytic phage is released which causes the host cell to burst. Lysis results in the cell breaking apart and degradation of the cell wall occurs by peptidoglycan hydrolases (endolysins)

Question 12

What do each class of endolysins display?

Answer 12

Different catalytic activity ie they cleave different bonds within the structure

Question 13

What is the structure of endolysins?

Answer 13

Single polypeptides with two domain structure

1. Peptidoglycan (PG) binding domain that provides specificity
2. Catalytic domain that cleaves PG

Question 14

How do certain types of endolysins act? And what has this prompted?

Answer 14

Synergistically

Prompted the suggestion that it may be possible to produce single hybrid endolysin that has enhanced activity

Question 15

What would endolysins primarily target against?

Answer 15

Gram positives due to the presence of LPS in Gram negative

Question 16

What happened when endolysins were added to Staph. aureus?

Answer 16

Lysis occurred instantly with limited potential for development of resistance

Question 17

What do endolysins do when used alongside β-lactams?

Answer 17

Shown to increase effectiveness of some antibiotic therapy through re-sensitisation

Question 18

What is Staphefekt?

Answer 18

An endolysin product for treating acne and eczema