ISOLATION AND CHARACTERIZATION OF A DNA VIRUS INFECTING FELDMANNIA SIMPLEX (PHAEOPHYCEAE)

We report on the isolation and characterization of a virus that is for med in modified zoidangia of the marine brown alga Feldmannia simplex (Crouan) Hamel (Ectocarpales, Phaeophyceae). Isolated virus particles had a buoyant density of about 1.35 g.mL(-1) in CsCl equilibrium gradi ents. They contained one major polypeptide (MW = 55,000) and at least six additional polypeptides (MW = 15,000-120,000). Four of these prote ins were glycosylated, The viral genome consisted of double-stranded D NA and formed two freely migrating fractions in pulsed-field-gel elect rophoresis, namely linear DNA with a size of 220 kilobase pairs, and f ragments of 10-60 kilobase pairs. However, electron microscopic examin ation revealed that a substantial fraction of the viral DNA occurred a s closed circles. We suggest that the viral DNA in native particles is circular but tends to break at random sites during the preparation.