About this Research Topic
Mycoviruses, viruses that infect fungi, were first discovered ca. 1960 in Agaricus bisporus and Penicillium chrysogenum, and later in Saccharomyces cerevisiae as killer viruses (originally considered RNA plasmids). Since the 1970s, many mycoviruses infecting plant pathogens such as rice blast fungus (Magnaporthe oryzae) and oat Victoria leaf blight fungus (Helminthosporium victorie) have been discovered. Among them, the hypovirus that infects the chestnut blight fungus (Cryphonectria parasitica) and attenuates the host fungus, has established a leading position as a model for mycovirus research. Since the 1990s, mycoviruses have also been discovered in the human pathogenic fungus Aspergillus fumigatus attracting attention in the medical science field. Several infected phytopathogenic fungi exhibit hypovirulence, i.e., mycovirus infection weakens the virulence of the host fungus. Conversely, there have also been several reports on mycoviruses that cause hypervirulence in host fungi.
Subsequently, viruses similar to mycoviruses have been found to infect hosts beyond the fungal kingdom. Indeed, viruses related to mycoviruses have been found in healthy plant crops, in seaweeds and microalgae that grow naturally on the coast, in oomycetes, in intracellular protozoan parasites such as Leishmania and Giardia spp., and in insects. Currently, an increasing number of mycoviruses and related viruses have been identified through meta-transcriptomics, however the structure of their genomes still needs to be fully unraveled. Mycoviruses and related viruses are currently classified into nineteen families as described by the International Committee on Taxonomy of Viruses (ICTV). Many mycoviruses were initially identified as double-stranded RNA genomes. Recently, however, positive-sense and negative sense single stranded RNA mycoviruses have been reported.
In this Research Topic, we would like to explore mycoviruses and related viruses that infect lower eukaryotes, plants, and insects. Mycoviruses are sometimes involved in epigenetic modification of host organisms and updates on these mechanisms are welcome. Further, we welcome reports on the evolution and ecology of mycoviruses and related viruses. Specifically, we invite manuscripts that investigate the impact of mycoviruses and related viruses on host organisms. Novel insights on the transmission mechanisms of these viruses and the expansion of their host range beyond the lower eukaryotes are of special interest.
Please note that only manuscripts describing viruses that belong to families for which known mycoviruses have been classified will be considered in this Research Topic. Descriptive studies that do not significantly advance our biological understanding of these viruses will not be considered for peer-review.
Keywords: mycovirus, RNA virus, vertical transmission, horizontal infection, modulating host traits
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