A Feldmannia algal virus has two genome size-classes

Area of Science:

• Marine Biology
• Virology
• Phycology (Study of Algae)

Background:

• Persistent viruses are known to occur intracellularly in brown algae, particularly within the Ectocarpales order.
• The genus Feldmannia, comprising small filamentous brown algae, is identified as a host for these viruses.

Purpose of the Study:

• To characterize a novel viral infection within the brown alga Feldmannia.
• To investigate the nature of viral particles replacing normal spore formation in sporangia.

Main Methods:

• Microscopic observation of Feldmannia sporangia to identify viral particle formation.
• Isolation and characterization of viral dsDNA genomes (158 and 178 kbp).
• Construction of a cosmid library for generating circular restriction enzyme maps (BamHI, NotI, PstI).

Main Results:

• Feldmannia sporangia were found to contain approximately 10^6 polyhedral viruses per cell instead of haploid zoospores.
• Two distinct double-stranded DNA (dsDNA) genome classes, 158 and 178 kilobase pairs (kbp), were identified, each with two restriction site variants.
• The relative abundance of each viral genome was influenced by culture temperature.
• Circular restriction maps were generated for the viral genomes.

Conclusions:

• This study reports the intracellular occurrence of polyhedral viruses in the brown alga Feldmannia, replacing typical zoospore production.
• The characterization of two dsDNA genome classes and their temperature-dependent abundance provides insights into viral biology in algae.
• The findings contribute to understanding the complex interactions between viruses and marine eukaryotic hosts.