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A novel filamentous phage, fs-2, of Vibrio cholerae O139
Abstract:
A novel filamentous bacteriophage, fs-2, was isolated from Vibrio cholerae O139 strain MDO14. The fs-2 phage was a long filamentous particle 1200 nm long and 7 nm wide. The purified phage formed a turbid plaque when spotted on a lawn of the host organisms. The plaque-formation activity was stable following heating to 70 degrees C but was inhibited by treatment with chloroform. fs-2 had a single-stranded DNA genome and was converted to a double-stranded replicative form in the host cell. Almost all V. cholerae O139 and O1 El Tor biotype strains tested were sensitive to the phage, but most O1 classical strains and non-O1 non-O139 strains were resistant. The fs-2 genome comprised 8651 nucleotides containing nine open reading frames, five of which had predicted protein products partially homologous to the reported protein products of other filamentous phages. Although the extent of the homology was not particularly high, the genetic organization of other filamentous phages appears to be preserved in fs-2. The phage was not integrated into the chromosome of its host, but a 715 nucleotide fragment located in the large intergenic region of fs-2 was highly homologous to a part of region RS2 (repetitive sequence 2) of the V. cholerae CTX phi sequence which is speculated to be required for integration of the phage into the V. cholerae chromosome at a specific site.
Insights
A new filamentous bacteriophage, fs-2, was discovered in Vibrio cholerae O139. This phage shows specific host sensitivity and possesses a genome with similarities to other filamentous phages.
Area of Science:
- Microbiology
- Virology
- Genetics
Background:
- Filamentous bacteriophages are important tools in molecular biology and phage therapy.
- Vibrio cholerae is a significant human pathogen, and understanding its phages can provide insights into its biology and evolution.
Purpose of the Study:
- To isolate and characterize a novel filamentous bacteriophage from Vibrio cholerae O139.
- To investigate the host range, genomic features, and potential integration mechanisms of the new phage.
Main Methods:
- Isolation and purification of bacteriophage fs-2 from Vibrio cholerae O139.
- Determination of phage morphology, plaque formation, and stability under different conditions.
- Genome sequencing and analysis, including identification of open reading frames and homology searches.
- Phage sensitivity testing against various Vibrio cholerae strains.
Main Results:
- A novel filamentous bacteriophage, fs-2, was isolated, measuring 1200 nm in length and 7 nm in width.
- Phage fs-2 exhibited plaque-forming activity stable at 70°C but sensitive to chloroform.
- The phage has a single-stranded DNA genome of 8651 nucleotides with nine open reading frames, showing partial homology to other filamentous phages.
- fs-2 demonstrated sensitivity against most V. cholerae O139 and O1 El Tor strains, but resistance in O1 classical and non-O1/non-O139 strains.
- A specific fragment within fs-2 showed high homology to the CTX phi integration region RS2.
Conclusions:
- The novel filamentous bacteriophage fs-2 is characterized by its unique morphology, host range, and genomic organization.
- fs-2 shares genetic similarities with other filamentous phages, suggesting conserved evolutionary pathways.
- The homology of a specific fs-2 fragment to the CTX phi integration region suggests a potential role in V. cholerae chromosome integration.