Comparative characterization of inducible and virulent Vibrio parahaemolyticus bacteriophages having unique head...

Phage TP1, induced from Vibrio parahaemolyticus K-20 pilot strain by mitomycin C, exhibited a unique hexagonal head with knob-like projections which covered the whole capsid and a noncontractile tail. The appearance of this phage was very similar to those of phages VP3 and VP6, isolated from seawater. The host range of phage TP1 was similar to those of phages VP3 and VP6. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the three phage particles revealed almost identical patterns with four major polypeptides with apparent approximate molecular masses: 78, 42, 37 and 34.5 kDa. On the basis of HindIII digestion patterns on agarose gel electrophoresis, the lengths of phage TP1 and VP3 DNAs were estimated to be about 65 kilobase pairs (kbp) and that of VP6 DNA was about 74 kbp. The digestion patterns of all three phage DNAs by DraI, BamHI and MspI were very similar. The DNAs of TP1 and VP3 exhibited almost the same digestion patterns with HindIII and EcoRI, whereas the digestion patterns of VP6 DNA were significantly different from those of the former. From these findings, it seems likely that virulent phage VP3 is originated from a lysogenic phage, probably TP1, of V. parahaemolyticus.