Molecular diagnosis of Marteilia sydneyi (Paramyxea) in Sydney rock oysters, Saccostrea commercialis (Angas)

Abstract. To prepare a diagnostic test, the polymerase chain reaction (PCR) with universal primers was used to amplify the internal transcribed spacer 1 (ITS1) of Marteilia sydneyi rDNA. A radiolabelled probe for M. sydneyi comprising putative ITS1 rDNA gave a strong signal for genomic DNA from M. sydneyi and no signal for host genomic DNA in Southern blots. A PCR to detect M. sydneyi used a forward primer designed from an internal site within the sequenced region and a reverse universal primer. It amplified a 650‐bp fragment of M. sydneyi DNA when a combination of host and parasite DNA, extracted from an infected oyster, was used as the template