First report of Perkinsus olseni infections in blood cockles Tegillarca granosa on the south coast of Korea

Abstract

The protozoan parasite Perkinsus olseni has become a focus of attention since it has been responsible for mass mortalities and economic losses in a wide range of bivalve hosts globally. The P. olseni host range along the south coast of Korea may extend beyond what was previously understood, and blood cockles in the Family Arcidae are also suggested to be potential hosts of P. olseni. In the present study, we applied histology and molecular techniques to identify Perkinsus sp. infections in the blood cockles Tegillarca granosa, which have been commercially exploited on the south coast of Korea for several decades. Histology and molecular techniques, including genus-specific immunofluorescence assay, species-specific fluorescence in situ hybridization, and phylogeny based on the ribosomal DNA internal transcribed spacer region revealed that T. granosa is infected by P. olseni, although the prevalence was low (0.5%). Histology revealed massive hemocyte infiltrations in the mantle, gill, and digestive gland connective tissues, indicating that the infection exerts negative impacts on the host cockles.