Summary: | <i>Aeromonas hydrophila</i> is an opportunistic pathogen that infects fish, amphibians, mammals, and humans. This study isolated a myophage, vB_AhyM_Ahp2 (Ahp2), that lytically infects <i>A. hydrophila</i>. We observed that 96% of the Ahp2 particles adsorbed to <i>A. hydrophila</i> within 18 min. Ahp2 also showed a latent period of 15 min with a burst size of 142 PFU/cell. This phage has a linear double-stranded DNA genome of 47,331 bp with a GC content of 57%. At least 20 Ahp2 proteins were detected by SDS-polyacrylamide gel electrophoresis; among them, a 40-kDa protein was predicted as the major capsid protein. Sequence analysis showed that Ahp2 has a genome organization closely related to a group of <i>Aeromonas</i> phages (13AhydR10RR, 14AhydR10RR, 85AhydR10RR, phage 3, 32 Asp37, 59.1), which infect <i>Aeromonas hydrophila</i> and <i>Aeromonas salmonicida</i>. The tail module encompassing ORF27-29 in the Ahp2 genome was present in all <i>Aeromonas</i> phages analyzed in this study and likely determines the host range of the virus. This study found that Ahp2 completely lyses <i>A. hydrophila</i> AH300206 in 3.5 h at a MOI of 0.0001 and does not lysogenize its host. Altogether, these findings show that Ahp2 is a lytic <i>Aeromonas</i> phage and could be a candidate for therapeutic phage cocktails.
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