ISOLATION AND CHARACTERIZATION OF A VIRUS INFECTING PHAEOCYSTIS-POUCHETII (PRYMNESIOPHYCEAE)

A virus infecting the haptophyte Phaeocystis pouchetii (Hariot) Lagerh eim was isolated from Norwegian coastal waters in May 1995 at the end of a bloom of this phytoplankter. The virus was specific for P. pouche tii because it did not lyse 10 strains of P. globosa Scherffel, Phaeoc ystis sp., and P. antarctica Karsten. It was a double-stranded DNA vir us, and the viral particle was a polyhedron with a diameter of 130-160 nm. The virus had a main polypeptide of about 59 kDa and at least fiv e minor polypeptides between 30 and 50 kDa. The latent period of the v irus when propagated in cultures of P. pouchetii was 12-18 h, and the time required for complete lysis of the cultures was about 48 h. The b urst size was estimated to be 350-600 viral particles per lysed cell.