Diversity, Ecology and Evolution of Archaeal Viruses

A prominent feature of archaea is the remarkable diversity of their viruses. Archaeal viruses represent one of the most unexplored and mysterious part of the global virosphere. Many archaeal viruses do not share evolutionary relationships, structural features, or genomic characteristics with viruses of bacteria or eukaryotes. Recent cultivation and metagenomic-based studies have uncovered several novel groups of viruses that infect archaeal extremophiles and mesophiles in diverse habitats. Viral ecology research has revealed important roles of archaeal viruses in influencing microbial communities, in particular in aquatic ecosystems. Many archaeal viruses are also good candidates for genetic tool development due to their stability in extreme physiochemical conditions.

The goal of this Research Topic is to promote publications of recent advances in archaeal virus research. In spite of pioneer studies, the vast diversity of archaeal viruses and their interactions with hosts are still hardly explored. The approach of isolating archaeal virions from environments is obstructed by the difficulty in culturing their archaeal hosts at the first place. Metagenome sequencing has revealed a tremendous amount of potential viral sequences from environments. A considerable proportion of them likely belong to archaeal viruses. However, few of these sequences can be successfully classified because of the very small refence databases of archaeal viruses. Metatranscriptional sequencing data are relatively scarce so the discovery of RNA archaeal viruses has lagged. A much higher diversity in morphology of archaeal viruses than bacteriophages suggests a complex history of origin of the former. This also implies that they may have unique virion structures and mechanisms in interacting with host cells, such as their lifecycles and novel defense/ antidefense systems. Pioneer studies have suggested crucial roles of archaeal viruses in element cycling in deep sea sediment and in modulating human gut health, but their potential impacts on ecology and physiology is still yet to be discovered.

Important scientific questions in archaeal virus studies include the accurate estimation of their overall diversity, their multiple origins and taxonomy, archaeal viruses with typical or atypical virion structures (e.g. envelopes) or life cycles, novel defense system and anti-defense system of the archaeal hosts and their viruses, RNA viruses and reverse transcriptional viruses, Asgard archaea viruses, mechanisms of archaea-viruses interactions, and their ecological contributions. We also encourage submissions on the development of molecular tools based on archaeal virus discoveries, field or laboratory technologies in viral isolation, single cell/virus approaches, and bioinformatic tools for viral (meta)genomic and evolutionary study. Original Research, Review or Methods articles are all welcomed.

Keywords: archaeal viruses, evolution, ecology, diversity, genetic tools

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.