A DNA VIRUS INFECTING THE MARINE BROWN ALGA PILAYELLA-LITTORALIS (ECTOCARPALES, PHAEOPHYCEAE) IN CULTURE

A new large DNA virus (PlitV-1) infects the marine filamentous brown a lga Pilayella littoralis. It was collected in Alaska and infects other P. littoralis isolates of different geographic origin. The virus has an icosahedral capsid of c. 161 nm in diameter, enclosing an electron- dense core. The genome consists of double-stranded DNA and is approxim ately 280 000 base pairs in size. The virus is latent in somatic cells of the host and is propagated only upon induction of the host's repro ductive organs. It causes deformed sporangia, resulting in infertility , and is structurally similar to other brown algal viruses. PCR amplif ication of a genomic sequence coding for part of a structural glycopro tein of the Ectocarpus siliculosus virus EsV-1 produced a fragment of similar size to that obtained with EsV-1.