Family: Fuselloviridae (interim Report)

This is a summary page created by the ICTV Report Editors using information from associated Taxonomic Proposals and the Master Species List.

Edited by: Mart Krupovic
Posted: July 2023


The family Fuselloviridae includes viruses with spindle-shaped virions and circular dsDNA genomes. Members of the family Fuselloviridae are temperate viruses infecting hyperthermophilic archaea of the order Sulfolobales (Table 1.Fuselloviridae). The family was established in 1990 as SSV-1 family, being renamed Fuselloviridae in 1993.

Table 1.Fuselloviridae. Characteristics of members of the family Fuselloviridae.

ExampleSulfolobus spindle-shaped virus 1 (X07234), species Sulfolobus spindle-shaped virus 1, genus Alphafusellovirus
VirionMembers of the genus Alphafusellovirus have lemon-shaped virions, about 90 × 50 nm in diameter, whereas viruses of the genus Betafusellovirus have elongated, cigar-shaped virions. One pole of the virion contains short terminal fibres. Lipids are present but the virions are not enveloped.
GenomeCircular, double-stranded DNA genomes of 14.8 to 17.8 kbp.
Host rangeHyperthermophilic archaea of the order Sulfolobales
Taxonomy2 genera and 9 species



Fuselloviridae genome
Figure 1.Fuselloviridae. Genome organisation of Sulfolobus spindle-shaped virus 1, a member of the family Fuselloviridae. Boxes indicate open reading frames as annotated on GenBank accession X07234. The annotation of this accession is incomplete – refer to (Iverson et al., 2017) for a more complete genome diagram.
Fuselloviridae taxonomy
Figure 2.Fuselloviridae. Relationships of the taxa connected to the family Fuselloviridae.

Derivation of name

Fuselloviridae: from fusillo, latin for little spindle


Iverson, E. A., D. A. Goodman, M. E. Gorchels and K. M. Stedman (2017). Extreme mutation tolerance: nearly half of the archaeal fusellovirus Sulfolobus spindle-shaped virus 1 genes are not required for virus function, including the minor capsid protein gene vp3. J Virol 91: e02406-16. [PMID 28148789]