Bacteriophage That Infect Gordonia Species Show Varying Host Specificity and Infection

Bacteriophage (phage) are an incredibly abundant species of virus that infect bacteria. One major characteristic of phage is their small host range- many phage are known to infect only one or a few hosts. This phage and host relationship has led to phage therapy recently becoming highlighted as a possible alternative to traditional antibiotics in light of the growing antibiotic resistance crisis. The study of phage host specificity has risen in line with this concept, as a phage with a more extensive host range can provide more opportunities for use as an antibiotic. Samples of phage previously isolated on a single Gordonia host were serially diluted and plated on both Gordonia rubripertincta and Gordonia terrae. The calculated titer and nature of plaques were recorded following two trials. Three main types of infection were identified: Types A, B, and C; and the phage were sorted according to their performance. Type A is characterized by little to no infection and plaque formation. Type B shows a fading infection with no countable plaques. Type C infection is seen in phage that showed a nearly identical or identical level of infection on both the isolation host and test host strains. The phage that exhibited Type C infection had a similarity in genes, specifically those related to tail proteins, which may indicate the role tail proteins play in host specificity. The genomes of sequenced phage in the PhagesDB database were compared to investigate similarities among phage with the same infection type. These findings indicate that even phage that infect the same host have different effects on other hosts. A similarity in tail proteins may indicate the ability to infect new hosts other than the original. More testing is necessary to investigate the extent of host range amongst known phage and what this might mean for further phage-based scientific research.