Mycoviruses

Mycoviruses are a diverse group of viruses that specifically infect fungi, including yeasts, molds, and mushrooms. These viruses, often referred to as mycoviruses, are typically double-stranded RNA (dsRNA) viruses, though some single-stranded RNA (ssRNA) and DNA viruses have also been identified. They are generally non-cellular and rely entirely on their fungal hosts for replication and propagation.

Mycoviruses were first discovered in the 1960s, though their existence was initially met with skepticism due to the difficulty of isolating and culturing them outside of their fungal hosts. Since then, research has expanded significantly, revealing that mycoviruses are widespread across various fungal species. They are often transmitted vertically, meaning they are passed from parent cells to daughter cells during fungal reproduction, though horizontal transmission—spread between unrelated fungal individuals—can also occur.

The effects of mycoviruses on their hosts vary widely. Some mycoviruses are asymptomatic, meaning they do not visibly affect the fungus, while others can cause hypovirulence, a reduction in the fungus's pathogenicity. This phenomenon has been particularly studied in *Cryphonectria parasitica*, the causal agent of chestnut blight, where certain mycoviruses have been used in biological control efforts to suppress the disease. Conversely, some mycoviruses may enhance fungal virulence or alter growth patterns, though such cases are less common.

Mycovirus research has practical implications in agriculture, forestry, and biotechnology. By manipulating mycoviruses, scientists aim to develop more effective disease-resistant fungal strains, improve industrial fermentation processes, and explore their potential in gene therapy and synthetic biology. Additionally, mycoviruses serve as model organisms for studying viral genetics, host-virus interactions, and the evolution of RNA viruses.