More's the Same-Multiple Hosts Do Not Select for Broader Host Range Phages

Bacteriophage host range is a result of the interactions between phages and their hosts. For phage therapy, phages with a broader host range are desired so that a phage can infect and kill the broadest range of pathogen strains or related species possible. A common, but not well-tested, belief is that using multiple hosts during the phage isolation will make the isolation of broader host range phage more likely. Using a Bacillus cereus group system, we compared the host ranges of phages isolated on one or four hosts and found that there was no difference in the breadth of host ranges of the isolated phages. Both narrow and broader host range phage were also equally likely to be isolated from either isolation procedure. While there are methods that reliably isolate broader host range phages, such as sequential host isolation, and there are other reasons to use multiple hosts during isolation, multiple hosts are not a consistent way to obtain broader host range phages.

Automated summary

The host range of bacteriophages is determined by their interactions with hosts. Broader host range phages are preferred for phage therapy to target a wide range of pathogen strains or related species. Using multiple hosts during phage isolation does not increase the likelihood of isolating broader host range phages, as shown in a study on the Bacillus cereus group system. Both narrow and broader host range phages can be isolated regardless of the isolation procedure. Other methods, such as sequential host isolation, are more reliable for obtaining broader host range phages.