A Feldmannia algal virus has two genome size-classes.

Persistent viruses occur intracellularly in brown algae, specifically the Ectocarpales, and as reported here in the genus Feldmannia. Feldmannia species are small (1 mm-several cm), filamentous forms with single-celled meiotic sporangia that normally produce haploid zoospores. In the isolate reported here, spores were not observed in the sporangia but rather numerous (approximately 10(6) per cell) polyhedral viruses are formed in their place. Two dsDNA genome classes of 158 and 178 kbp, with two restriction site variants of each, are described. The individual abundance of each genome in viral preparations is affected by culture temperature. A cosmid library was used to generate circular restriction enzyme (BamHi, Noti, and Psti) site maps.