Bicaudaviridae is a family of hyperthermophilic archaeal viruses. Members of the genus Acidianus serve as natural hosts. There is only one genus (Bicaudavirus) and one species in this family: Acidianus two-tailed virus.[1][2][3] However, Sulfolobus tengchongensis spindle-shaped viruses 1 and 2 (STSV1 and STSV2) are regarded to belong to this family also.[4]
The genus contains one genus, which contains one species:[5]
Viruses in Bicaudaviridae are non-enveloped, with lemon-shaped geometries. Genomes are circular dsDNA molecules of around 48–76 kb in length. High-resolution structure was determined by cryo-EM for Sulfolobus monocaudavirus 1 (SMV1) and a lower-resolution structure was determined for Acidianus two-tailed virus (ATV).[6] Virions of both viruses have helical symmetry, with continuous 7-start helices, composed of the single major capsid protein, forming both the tails and the spindle-shaped body. The major capsid protein structure and virion organization of bicaudaviruses are similar to those of archaeal viruses from the families Fuselloviridae, Thaspiviridae, Halspiviridae and Clavaviridae.[6]
Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment of the viral proteins to host receptors. DNA-templated transcription is the method of transcription. Diverse species of hyperthermophilic archaea from the order Sulfolobales serve as the natural hosts. Transmission routes are passive diffusion.[2] It has been demonstrated that certain members of the family, namely, STSV2 and Sulfolobus monocaudavirus 1 (SMV1), induce cell gigantism by blocking the expression of the cell division genes and arresting the cell cycle in the S phase.[7] The diameter of infected cells increases up to 20 times, resulting in 8,000-fold increase in volume compared to noninfected cells.[7]
This family was first described by the team led by D. Prangishvili in 2005.[8][9]
The name is derived from the Latin word 'bi' and 'cauda' meaning 'two-tail'.
Bicaudaviridae is a family of hyperthermophilic archaeal viruses. Members of the genus Acidianus serve as natural hosts. There is only one genus (Bicaudavirus) and one species in this family: Acidianus two-tailed virus. However, Sulfolobus tengchongensis spindle-shaped viruses 1 and 2 (STSV1 and STSV2) are regarded to belong to this family also.
