Abstract
Algae are photosynthetic organisms that drive aquatic ecosystems, e.g. fuelling food webs or forming harmful blooms. The discovery of viruses that infect eukaryotic algae has raised many questions about their influence on aquatic primary production and their role in algal ecology and evolution. Although the full extent of algal virus diversity is still being discovered, this review summarizes current knowledge of this topic. Where possible, formal taxonomic classifications are referenced from the International Committee on Taxonomy of Viruses (ICTV); since the pace of virus discovery has far surpassed the rate of formal classification, however, numerous unclassified viruses are discussed along with their classified relatives. In total, we recognized 61 distinct algal virus taxa with highly variable morphologies that include dsDNA, ssDNA, dsRNA, and ssRNA genomes ranging from approximately 4.4 to 560 kb, with virion sizes from approximately 20 to 210nm in diameter. These viruses infect a broad range of algae and, although there are a few exceptions, they are generally lytic and highly species or strain specific. Dedicated research efforts have led to the appreciation of algal viruses as diverse, dynamic, and ecologically important members of the biosphere, and future investigations will continue to reveal the full extent of their diversity and impact.
Highlights
Algae are the engines of aquatic ecosystems that convert inorganic matter into organic matter and fuel aquatic food webs
This study provided compelling evidence that nucleocytoplasmic large DNA viruses (NCLDVs), phycodnaviruses and megaviruses, and Single-stranded RNA (ssRNA) viruses closely related to the dinoflagellateinfecting virus HcRNAV were associated with the coral algal symbiont, and that viruses could be a major source of mortality for coral symbionts and play a significant role in coral health
We have come a long way since the discovery and isolation of the Double-stranded DNA (dsDNA) viruses that infect Chlorellalike algae and that led to the establishment of the prominent algal virus family, the Phycodnaviridae
Summary
Algae are the engines of aquatic ecosystems that convert inorganic matter into organic matter and fuel aquatic food webs. A subsequent study by the same researchers expanded these results and attempted to link prasinovirus and host diversity, and determined that the unknown virus sequences that did not cluster with cultivated prasinoviruses of Bathycoccus, Ostreococcus, and Micromonas (order Mamiellales) probably infect prasinophyte species within the closely related algal order, Dolichomastigales (Clerissi et al, 2015).
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