Characterization of myophage AM24 infecting Acinetobacter baumannii of the K9 capsular type

In the present study, we investigate the biological properties and genomic organization of virulent bacteriophage AM24, which specifically infects multidrug-resistant clinical Acinetobacter baumannii strains with a K9 capsular polysaccharide structure. The phage was identified as a member of the family Myoviridae by transmission electron microscopy. The AM24 linear double-stranded DNA genome of 97,177 bp contains 167 open reading frames. Putative functions were assigned for products of 40 predicted genes, including proteins involved in nucleotide metabolism and DNA replication, packaging of DNA into the capsid, phage assembly and structural proteins, and bacterial cell lysis. The gene encoding the tailspike, which possesses depolymerase activity towards the corresponding capsular polysaccharides, is situated in the phage genome outside of the structural module, upstream of the genes responsible for packaging of DNA into the capsid. The data on characterization of depolymerase-carrying phage AM24 contributes to our knowledge of the diversity of viruses infecting different capsular types of A. baumannii .