There has been a growing interest in bacteriophages as therapeutic agents to treat multidrug-resistant bacterial infections. The present work aimed at expanding the microbiological and molecular characterization of lytic phages ZC01 and ZC03 and investigating their efficacy in the control of
Pseudomonas aeruginosa
infection in an invertebrate animal model. These two phages were previously isolated from composting using
P. aeruginosa
strain PA14 as the enrichment host and had their genomes sequenced. ZC01 and ZC03 present, respectively, siphovirus and podovirus morphotypes. ZC01 was recently classified into the genus
Abidjanvirus
, while ZC03 belongs to
Zicotriavirus
genus of the
Schitoviridae
N4-like viruses. Through proteomics analysis, we identified virion structural proteins of ZC01 and ZC03, including a large virion-associated RNA polymerase that is characteristic of N4-like viruses, some hypothetical proteins whose annotation should be changed to virion structural proteins and a putative peptidoglycan hydrolase. Phages ZC01 and ZC03 exhibit a limited yet distinct host range, with moderate to high efficiency of plating (EOP) values observed for a few
P. aeruginosa
clinical isolates. Phage susceptibility assays in PA14 mutant strains point to the type-IV pilus (T4P) as the primary receptor for phages ZC01 and ZC03, and the major pilin (PilA
PA14
) is the T4P component recognized by these phages. Moreover, both phages significantly increase survival of
Galleria mellonella
larvae infected with PA14 strain. Taken together, these results underpin the therapeutic potential of these phages to treat infections by
P. aeruginosa
and lay the groundwork for a more detailed investigation of phage-bacteria-specific recognition mechanisms.
IMPORTANCE
Phage therapy is gaining increasing interest in cases of difficult-to-treat bacterial human infections, such as carbapenem-resistant
Pseudomonas aeruginosa
. In this work, we investigated the molecular mechanism underlying the interaction of the lytic phages ZC01 and ZC03 with the highly virulent
P. aeruginosa
PA14 strain and their efficacy to treat PA14 infection in
Galleria mellonella
larvae, a commonly used invertebrate model for phage therapy. We depicted the protein composition of ZC01 and ZC03 viral particles and identified pilin A, the major component of type-4 pilus, as the receptor recognized by these phages. Our findings indicate that phages ZC01 and ZC03 may be further used for developing therapies to treat multidrug-resistant
P. aeruginosa
infections.