Hypovirulence

Hypovirulence refers to a decrease in the virulence of a pathogen, such as a fungus or virus. This means the pathogen becomes less able to cause disease in its host. Hypovirulence is often observed in plant pathogens, where it can lead to a significant reduction in the severity of diseases that impact crops. For example, the fungus Cryphonectria parasitica, which causes chestnut blight, exhibits hypovirulence when infected by specific viruses. These viruses, known as hypoviruses, alter the fungal pathogen's physiology, making it less aggressive and less capable of killing its host tree.

The phenomenon of hypovirulence has important implications for biological control. In cases where a pathogen's virulence is reduced by a biological agent like a virus, that agent can be intentionally introduced into a population of the pathogen to manage disease outbreaks. This approach has been successfully employed to control chestnut blight in some regions. However, the effectiveness of hypovirulence as a biocontrol strategy can be influenced by various factors, including the genetic diversity of both the pathogen and the hypovirulent agent, as well as environmental conditions. Research continues to explore the mechanisms behind hypovirulence and its potential applications in disease management across different organisms.