Guttaviridae

Guttaviridae

Legend. Image credit: Name or Publication.

Classification

Domain: Viruses; Realm: Varidnaviria; Kingdom: Bamfordvirae; Phylum: Nucleocytoviricota; Class: Nucleocytoviricetes; Order: Currently, there is not an assigned order for Guttaviridae; Family: Guttaviridae; Species: Sulfolobus newzealandicus droplet-shaped virus (SNDV); Genus: Betaguttavirus

Description and Significance

Guttaviridae is a family of enveloped viruses that infect hyperthermophilic archaea. Their virions are droplet-shaped or ovoid-shaped, typically with a diameter of 55-80 nm and has a width of 75-130 nm. Their genome is a circular dsDNA molecule of around 14 kbp. The Guttaviridae family includes one genus, Bettaguttavirus, with a single species. Guttaviridae thrive in extremely hot environments like volcanic hot springs, making them significant for studying the limits of life and the evolution of viruses in extreme conditions. Their unique genetic makeup and structural features also contribute to our understanding of viral diversity across different domains of life.

Genome Structure

The genome structure of Guttaviridae consists of a double-stranded DNA (dsDNA) molecule that is circular in structure, and is typically around 14-20 kilobase pairs (kb) in length. This means Guttaviridae’s genome structure is a closed loop of DNA with both strands present, and is considered relatively large for a viral genome. It encodes a small number of genes, primarily those required for replication, capsid formation, and host interaction, relying heavily on the host's cellular machinery for its lifecycle. Guttaviridae genomes are known to be heavily methylated, meaning chemical modifications are added to the DNA bases. Their viruses are enveloped, meaning they have a lipid membrane surrounding their nucleocapsid.

Cell Structure, Metabolism and Life Cycle

Cell structure -Spindle-shaped virions with short tail-like projections at one end, giving them a distinctive "guttate" (droplet-like) appearance Protein capsid surrounding double-stranded DNA. The Guttaviridae virion surface, which is its protective shell that allows it to attach to and enter a host cell to replicate, is covered by globular subunits, which are about 3.5 nm in width. These droplet-shaped virions are unprecedented among viruses of bacteria and eukaryotes, and represents a group of archaea-specific virion morphotypes.

Metabolism-They cannot perform metabolic activity on their own, so they use a host cell machinery to replicate DNA, synthesize proteins, and produce new viral particles Infect Sulfolobus archaea, which are found in extremely hot and acidic environments, such as hydrothermal vents and hot springs

Life cycle-Attaches to the surface of a Sulfolobus cell and injects its genetic material into the host Viral DNA is replicated using the host’s enzymes, and viral proteins are synthesized. Newly formed viral particles are assembled within the host cell. Completed virions are released from the host cell, sometimes lysing the cell in the process, to infect other nearby Sulfolobus cells

Ecology and Pathogenesis

Ecology -APOV1 has been found to possibly share a common module with fuselloviruses, indicating that these two archaeal viruses may be evolutionarily related.

Pathogenesis -It only infects Sulfolobus isolate from New Zealand, which includes the STH1/3. Its early production starts in the early stationary phase. Once it infects its host, the genome is likely to be replicated by the hosts replisome. This is believed to be true because the APOV1 does not carry a gene for DNA polymerase. There have been no experiments conducted to confirm the truthfulness of this.

References

https://pmc.ncbi.nlm.nih.gov/articles/PMC5882108/ https://ictv.global/report_9th/dsDNA/Guttaviridae https://viralzone.expasy.org/6676

Author

Page authored by Lilli Gray Stanley, Sarah Grace Szymeczek, Karmela Ann Cotterell, & Walt Hinnnant, students of Prof. Bradley Tolar at UNC Wilmington.