Bicaudaviridae

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). 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. ==Life cycle==

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. The diameter of infected cells increases up to 20 times, resulting in 8,000-fold increase in volume compared to noninfected cells. ==History==

This family was first described by the team led by D. Prangishvili in 2005. The name is derived from the Latin word 'bi' and 'cauda' meaning 'two-tail'. ==References==