Detection and Identification of Miamiensis avidus Causing Scuticociliatosis by PCR

Abstract

We designed a PCR primer set for specific detection of Miamiensis avidus causing scuticociliatosis in Japanese flounder Paralichthys olivaceus. In the PCR targeting the small subunit ribosomal RNA gene of M. avidus, the expected PCR product with 1,433 bp was amplified from four isolates of M. avidus including three different serotypes, but not from other scuticociliates including Pseudocohnilembus persalinus, P. hargisi and Uronema marinum. Detection limit of the present PCR was 125 fg of genomic DNA. When a group of Japanese flounder suffering the disease was examined by the PCR, 90% of symptomatic fish and 50% of asymptomatic fish were found positive. Thus it is considered that the PCR is useful for detection and identification of M. avidus and consequently for diagnosis of scuticociliatosis in Japanese flounder.