Vibrio parahaemolyticus (VP) is a bacterial pathogen found in brackish and marine water that infects many marine organisms, like oysters and shrimp. Consumption of raw or undercooked seafood contaminated with VP is a primary cause of seafood-borne gastroenteritis in humans. Due to increasing ocean temperatures, VP contamination of oyster beds in the US has spread from around the Gulf of Mexico up the east and west coasts to the northern-most states. Promising new research is exploring the isolation of bacteriophages against VP with a long-term goal to possibly decontaminate oyster beds in order to expand the harvest season and allow for safer consumption of seafood.
Store-bought oysters harvested from the Chesapeake Bay in VA, were used to isolate four bacteriophages. A standard double agar overlay plaque assay was used to identify phage activity. After phage isolation, the genomes were sequenced, and transmission electron microscopy was completed (Figure 1). The genomes and TEM images show four distinct phages. Two of the phages have podovirus-like morphology with shorter tails and approximately 60 predicted proteins, one phage has siphovirus-like morphology with about 45 predicted proteins, and the 4th phage is a mid-sized tailed phage with 100 predicted proteins.
Plaque assays were carried out with the 4 bacteriophages and up to 10 different VP strains. (Table 1). CREW showed the widest host range and was capable of lysing 3 different VP strains. Future work will be necessary to determine the viability of using the bacteriophages for elimination of VP in harvested oysters and/or the environment.