Hypovirulence

CHV1 – Chestnut blight hypovirulence

Up to 2000, Hypovirus CHV1 was the only hypovirus found in Europe. It is known for reducing the virulence of the fungus that causes chestnut blight (i.e. hypovirulence). Cryphonectria parasitica, the ascomycete fungus, originated in Asia and causes the disease chestnut blight in several chestnut species (Castanea spp.). Although symptoms are mild in Asian chestnut species that have co-evolved with the fungus, they are very severe in the North American chestnut species C. dentata and also in the European sweet chestnut, C. sativa. Hypovirus has been used for protection against chestnut blight in Europe since the 1970s.