Phage S144, A New Polyvalent Phage Infecting Salmonella spp. and Cronobacter sakazakii

Area of Science:

• Microbiology
• Virology
• Genomics

Background:

• Bacteriophages are typically host-specific, but polyvalent phages can infect bacteria across different genera.
• The Loughboroughvirus genus includes phages with broader host ranges, necessitating further characterization.

Purpose of the Study:

• To characterize the novel polyvalent phage S144, including its host range, receptor, genome, and structure.
• To investigate the potential polyvalence of the Loughboroughvirus genus.

Main Methods:

• Screening of 211 Enterobacteriaceae strains to determine phage S144's host range.
• Analysis of phage-resistant mutants to identify the phage receptor.
• Genome sequencing and bioinformatic analysis of open reading frames (ORFs).
• ESI-MS/MS analysis to confirm structural proteins.
• Transmission electron microscopy to determine phage morphology.

Main Results:

• Phage S144 infected specific serovars of Salmonella enterica and Cronobacter sakazakii.
• The O-antigen of lipopolysaccharide was identified as the receptor for phage S144 in both genera.
• The S144 genome is 53,628 bp with 80 ORFs; 32 ORFs encode structural proteins.
• Phage S144 is a myovirus with a prolate head and short tail fibers, structurally similar to phage Mu.
• Tail fiber similarity suggests Loughboroughvirus phages infect Cronobacter sakazakii and are polyvalent.

Conclusions:

• Phage S144 exhibits polyvalence, infecting distinct bacterial genera.
• The O-antigen LPS is a crucial determinant for S144 infection in Salmonella and Cronobacter.
• Structural and genomic analyses provide insights into phage-host interactions and the Loughboroughvirus genus's characteristics.