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From interferon induction to fungal viruses
1Department of Pure and Applied Biology, Imperial College of Science and Technology, London, U.K.
Abstract:
Viruses of fungi (mycoviruses) were first discovered in diseased mushrooms. However the finding that the antiviral and interferon-inducing activities of extracts of apparently healthy isolates of a number of Penicillium species were due to the presence of double-stranded (ds) RNA arising from mycovirus infections sparked off an explosion of interest in what has now become a distinct area of virology. Two families of dsRNA mycoviruses are now established: the Totiviridae and the Partitiviridae which comprise isometric viruses with genomes of one or two dsRNA segments respectively. Virus isolates in both families often contain additional satellite dsRNAs, which may in some fungi (e.g. Saccharomyces cerevisiae, Ustilago maydis) code for "killer" proteins which are toxic to other sensitive strains of the same or closely related species. In Endothia parasitica, which causes chestnut blight disease, dsRNA is associated with hypovirulence and is enclosed in lipid-rich vesicles. In Ophiostoma (Ceratocystis) ulmi, which causes Dutch elm disease, dsRNA is associated with the mitochondria and, in some diseased isolates of the fungus, specific dsRNA segments are associated with reduction of cytochrome oxidase and respiratory deficiency, resulting in slow growth and abnormal morphology.
Insights
Mycoviruses, or fungal viruses, are double-stranded (ds) RNA viruses. These mycoviruses can impact fungal hosts, causing effects like hypovirulence or respiratory deficiency.
Area of Science:
- Virology
- Mycology
- Molecular Biology
Background:
- Mycoviruses were initially found in diseased mushrooms.
- The discovery of antiviral activities in healthy Penicillium isolates linked to mycovirus infections spurred significant research.
- Double-stranded (ds) RNA mycoviruses are now a distinct field of virology.
Purpose of the Study:
- To review the established families of dsRNA mycoviruses.
- To highlight the diverse impacts of mycoviruses on fungal hosts.
- To discuss the implications of mycoviral dsRNA in fungal diseases.
Main Methods:
- Literature review of mycovirus research.
- Classification of dsRNA mycoviruses into established families (Totiviridae, Partitiviridae).
- Analysis of documented effects of mycoviral dsRNA on fungal phenotypes.
Main Results:
- Two main families of dsRNA mycoviruses, Totiviridae and Partitiviridae, are recognized.
- Satellite dsRNAs can code for killer toxins in some fungal species.
- Mycoviral dsRNA is linked to hypovirulence in Endothia parasitica and respiratory deficiency in Ophiostoma ulmi.
Conclusions:
- Mycoviruses represent a significant area of virological study with diverse impacts.
- The presence of dsRNA in fungi can lead to altered host physiology and disease characteristics.
- Further research into mycoviruses can provide insights into fungal biology and disease management.