A NOVEL FILAMENTOUS PHAGE, FS-2, OF VIBRIO-CHOLERAE O139

A novel filamentous bacteriophage, fs-2. was isolated from Vibrio chol erae 0139 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 ac tivity was stable following heating to 70 degrees C but was inhibited by treatment with chloroform. fs-2 had a single-stranded DNA genome an d was converted to a double-stranded replicative form in the host cell . Almost all V. cholerae 0139 and 01 EI Tor biotype strains tested wer e sensitive to the phage, but most 01 classical strains and non-01 non -0139 strains were resistant. The fs-2 genome comprised 8651 nucleotid es containing nine open reading frames, five of which had predicted pr otein products partially homologous to the reported protein products o f other filamentous phages. Although the extent: of the homology was n ot particularly high, the genetic organization of other filamentous ph ages appears to be preserved in fs-2. The phage was not integrated int o 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 o f region RS2 (repetitive sequence 2) of the V. cholerae CTX Phi sequen ce which is speculated to be required for integration of the phage int o the V. cholerae chromosome at a specific site.