Family: Satyavativiridae

Apoorva Prabhu and Christian Rinke

The citation for this ICTV Report chapter is the summary to be published as Prabhu, A and Rinke, C. (2026) ICTV Virus Taxonomy Profile: Satyavativiridae 2026, Journal of General Virology, (in press)

Corresponding author: Apoorva Prabhu ([email protected])
Edited by: Mart Krupovic and Evelien Adriaenssens
Posted: February 2026
 

Summary

The family Satyavativiridae includes dsDNA viruses that are associated with marine archaea in the order Poseidoniales, formerly known as Marine Group II Euryarchaeota. Members of the family have been discovered using long read metagenomics, and the virions have been predicted to have icosahedral heads and helical tails, which are characteristics of viruses in the class Caudoviricetes. Virus genomes encode proteins for virion morphogenesis (major capsid protein, tail protein) but seem to lack a recognisable genome replication module. The family includes the genus Vyasavirus and the species Vyasavirus brisbanense.

Table 1 Satyavativiridae. Characteristics of members of the family Satyavativiridae

Virion

Morphology

Members of this family have been recovered using metagenomics (Nishimura et al., 2017, Philosof et al., 2017, Xu et al., 2023, Zhou et al., 2023, Prabhu et al., 2025). The genome of Poseidoniales virus P01 (species Vyasavirus brisbanense) encodes proteins involved in virion morphogenesis, including the HK97-fold major capsid protein and tail proteins, that are typical of viruses in the class Caudoviricetes (Figure 1 Satyavativiridae). Other morphogenesis proteins include prohead protease, portal protein, and the large subunit of the terminase. In addition to these proteins, they share genomic features (gene arrangement, size and major capsid protein phylogeny) with tailed haloviruses and are therefore predicted to have icosahedral heads and helical tails (Baquero et al., 2020, Liu et al., 2021).

Figure 1 Satyavativiridae. Genome organisation of Poseidoniales virus P01, a member of the family Satyavativiridae. Boxes indicate open reading frames as annotated on GenBank accession PP497040. Note that not all annotations are provided in the figure.

Nucleic acid

The complete genome of Poseidoniales virus P01 (species Vyasavirus brisbanense) was assembled as a circular contig of 87 kbp and is predicted to encode 85 proteins.

Genome organization and replication

The genome of Poseidoniales virus P01 does not appear to encode key replication proteins, such as DNA polymerase, suggesting that this virus is dependent on the host machinery for genome replication (Figure 1 Satyavativiridae).  

Biology

Satyavarivirids have been discovered using long-read sequencing of brackish estuarine samples, and have yet to be cultured (Nishimura et al., 2017, Philosof et al., 2017, Xu et al., 2023, Zhou et al., 2023). The lack of genes for integrase and transposase proteins suggests a lytic mode of replication. Other than the morphogenetic module, satyavativirid genomes encode several auxiliary metabolic genes (AMGs) such as metallophosphoesterase (MPEs), amidoligase, glutamine amidotransferase (GATase) and 2OG-Fe(II) oxygenase (Figure 1 Satyavativiridae) and other metabolic genes for overcoming oxidative stress, such as ferredoxin and prolyl 4-hydroxylase (Prabhu et al., 2025).

Derivation of names

Satyavativiridae: after Satyavati, the child of Adrika, who later became a Queen in ancient Indian mythology

Vyasavirus: from Vyasa, the child of Satyavati, a revered sage who compiled the Vedas in ancient Indian mythology

Demarcation criteria for taxa within the family

There is only one genus and one species in the family. Viruses belonging to additional species would be expected to have a genome sequence identity of <95% to the existing species, consistent with the demarcation criterion of other archaeal viruses within the class Caudoviricetes (Liu et al., 2021).

Relationships within the family

The family includes the single species Vyasavirus brisbanense (Figure 2 Satyavativiridae). Comparative genomics with unclassified viruses in IMG/VR and from Brisbane River Estuary dataset (PRJNA1024631) reveals a cluster of viruses sharing 20–40% of their genes, and these may represent additional genera.

Figure 2 Satyavativiridae. Relationship of taxa connected to the family Satyavativiridae.

Relationships with other taxa

Members of the family Satyavativiridae comprise a novel archaeal viral lineage placed outside the order Magrovirales.

Related, unclassified viruses

The closest viral genome to Poseidoniales virus P01 is Ga0213858_10000035 from the IMG/VR database, which shares 79% of predicted proteins; both genomes have < 95% ANI hence they may belong to different species.