Phage C-1: an IncC group; plasmid-specific phage

Area of Science:

• Microbiology
• Virology
• Bacteriology

Background:

• Bacteriophages are viruses that infect bacteria and can serve as valuable tools in molecular biology and medicine.
• IncC plasmids are a group of conjugative plasmids found in various Gram-negative bacteria, often carrying antibiotic resistance genes.
• Phage-host interactions are often specific and can be influenced by bacterial genetic elements like plasmids.

Purpose of the Study:

• To isolate and characterize a novel bacteriophage from sewage.
• To determine the host range and replication requirements of the isolated phage.
• To investigate the phage's interaction with bacteria carrying IncC plasmids.

Main Methods:

• Enrichment culture of sewage samples to isolate phages.
• Plaque assays on various bacterial strains (Salmonella typhimurium, Proteus mirabilis, Serratia marcescens, Escherichia coli) with and without IncC plasmids.
• Electron microscopy to determine phage morphology.
• Chloroform resistance assay.
• Adsorption assays to bacterial pili.

Main Results:

• A bacteriophage was isolated from sewage that forms plaques on Salmonella typhimurium strains carrying IncC plasmids.
• The phage failed to multiply on strains lacking IncC plasmids or those with other incompatibility groups.
• While plaque formation was limited in Escherichia coli, phage multiplication was demonstrated in various bacterial hosts carrying IncC plasmids.
• The phage is small, hexagonal, contains RNA, is chloroform-resistant, and adsorbs to pili encoded by IncC plasmids.

Conclusions:

• The isolated phage exhibits a specific requirement for IncC plasmids for plaque formation, suggesting a dependence on plasmid-encoded factors.
• The phage's ability to adsorb to pili coded by IncC plasmids indicates a potential mechanism for host recognition and entry.
• This phage represents a potential new tool for studying IncC plasmids and their associated bacterial hosts.