Phages and phage lysins in nature
Phages are the most abundant biological entity on earth. Approximately 10³¹ populate our planet and they outnumber bacteria 10:1. Phages hunt, infect and kill bacteria and are extremely precise – typically only capable of infecting a small number of bacterial strains.
Phages are bactericidal by nature and have the potential to be a highly innovative novel anti-bacterial that work where antibiotics fail. Their precision allows the precise targeting of individual bacterial strains within the beneficial microbiomes.
Many phages also encode a protein called a lysin. The phage needs the lysin in the last step of its replication cycle to cleave the bacterial cell wall. This kills the bacteria.
Lysins can also cleave the cell wall from the outside. This makes them a novel class of anti-bacterials with the potential to revolutionize the treatment of bacterial infections.
See below for a schematic representation of how phages and their lysins work.
Schematic representation of phages' and lysins' activity
Phages hunt for a specific bacteria to infect
Phages hijack the bacteria to produce new phage particles
Phages force the bacteria to assemble cell wall lysins
Lysins cleave the cell wall, the new phage particles escape
Phages and phage lysins as pharmaceuticals
The potential of phages and lysins as novel anti-bacterials have been well recognized over the past decades. However, phages and phage lysins found in nature typically have a number of drawbacks:
Limited host range
Limited potency & fast resistance formation
For more information on phages and lysins in general, the following publications are useful starting points: