Discovery of an opportunistic starfish pathogen, Orchitophrya stellarum, in captive blue crabs, Callinectes sapidus

• Published in: Journal of invertebrate pathology 2013-10, Vol.114 (2), p.178-185
• Main Authors: Small, H.J., Miller, T.L., Coffey, A.H., Delaney, K.L., Schott, E., Shields, J.D.
• Format: Article
• Language: English
• Subjects: Animals; Asterias; Biological and medical sciences; blood serum; Brachyura - parasitology; Callinectes sapidus; Ciliate; Ciliophora - genetics; crabs; Crustacea; Crustacean; Echinodermata; Fundamental and applied biological sciences. Psychology; gills; heart; hemolymph; hepatopancreas; internal transcribed spacers; Invertebrates; Maryland; Mesanophrys; muscles; Orchitophrya stellarum; Parasite; parasites; pathogens; Polymerase Chain Reaction; research facilities; restriction fragment length polymorphism; Starfish - parasitology; surveys; Virginia; winter
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2013.07.008

[Display omitted] •Orchitophrya stellarum identified infecting blue crabs, Callinectes sapidus, held in a research facility.•O. stellarum has previously only been described parasitizing wild sea stars.•Systemic infections were observed in affected blue crabs.•During in vitro culture the ciliate multiplies at temperatures between 4 and 20°C.•A PCR-RFLP assay was developed to detect and differentiate between O. stellarum and Mesanophrys chesapeakensis. Histophagous scuticociliate infections were discovered in blue crabs, Callinectes sapidus, held in research facilities at the Virginia Institute of Marine Science. Ciliates were observed infecting every tissue examined including the gills, heart, muscle, hepatopancreas, and epidermis. Hemolymph smears and histological tissue sections indicated a morphological similarity to Mesanophrys chesapeakensis, the only recorded histophagous ciliate infecting blue crabs. However, subsequent analysis of the ribosomal ITS region (ITS1-5.8S-ITS2) of the ciliate indicated the parasite was Orchitophrya stellarum, a parasitic ciliate previously reported infecting sea stars from Europe, Australia, and North America. A simple Polymerase Chain Reaction (PCR-RFLP) assay was developed to detect and differentiate between O. stellarum and M. chesapeakensis. Its application confirmed the presence of O. stellarum infecting blue crabs held in an additional research facility in Maryland. For growth studies, cultures of O. stellarum grew optimally on 10% blue crab serum in crustacean saline held at 10–20°C. A field survey of blue crabs collected during the winters of 2011–2012 and sea stars (Asterias forbesi) during the winter of 2010 from the Chesapeake Bay and eastern shore of Virginia did not identify additional infected individuals.