Curing Cryphonectria nitschkei BS122 of a novel chrysovirus CnV1-BS122 infection was achieved by plating small hyphal fragments from an old plate and protoplasting followed by regeneration. Uneven distribution of mycoviruses within colonies was suggested. Comparing the CnV1-BS122-cured and -infected isogenic strains revealed that CnV1-BS122 infection resulted in reduced mycelial growth. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.