The tail associated protein of Acinetobacter baumannii phage qab6 is the host specificity determinant possessing exopolysaccharide depolymerase activity

Abstract

Acinetobacter baumannii is a non-fermenting, gram-negative bacterium. In recent years, the frequency of A. baumannii infections has continued to increase, and multidrug-resistant strains are emerging in hospitalized patients. Therefore, as therapeutic options become limited, the potential of phages as natural antimicrobial agents to control infections is worth reconsidering. In our previous study, we isolated ten virulent double-stranded DNAA. baumannii phages, φAB1-9 and φAB11, and found that each has a narrow host range. Many reports indicate that receptor-binding protein of phage mediates host recognition; however, understanding of the specific interactions between A. baumannii and phages remains very limited. In this study, host determinants of A. baumannii phages were investigated. Sequence comparison of φAB6 and φ/AB1 revealed high degrees of conservation among their genes except the tail fiber protein (ORF41 in φAB1 and ORF40 in φAB6). Furthermore, we found that ORF40