Mortimer, E. & Patching J. W.
Microbiology Section, The Martin Ryan Marine Science Institute,
National University of Ireland, Galway, Ireland
In an attempt to isolate algal viruses indigenous to inner Galway Bay (W coast of Ireland), concentrates of the 20-200 nm particulate fraction from surface waters were added to cultures of phytoplankton species typically observed in the bay. Lysis was observed in a culture of Pyramimonas orientalis (Prasinophyceae). Electron micrographs of the algal cells showed structural damage and the presence of polygonal-shaped particles. Filtrates (<200 nm) of lysed cultures were used to inoculate further cultures to confirm that lysis was caused by a tail-less virus with a capsid diameter of 74 ± 7.9 nm (average ± standard deviation). These characteristics are similar to those previously described for the Phycodnaviridae. Restriction enzyme and nuclease studies showed the viral nucleic acid to be single-stranded DNA. PCR and RAPD (Random Amplified Polymorphic DNA) primers were used to randomly amplify regions (fragments) of the viral genome. Following subcloning and DNA sequencing of these fragments BLAST (Basic Local Alignment Search Tool) analyses were carried out. Initial results suggest similarity between the virus sequences and several known gene sequences of non-viral origin including protein-encoding genes. The development of a nucleic acid-based probe specific for the viral isolate is underway. This probe will be used for the study of virus/host dynamics in Galway Bay.