Betalipothrixvirus hveragerdiense (SIFV) is an archaeal virus, classified in the family Lipothrixviridae within the order Ligamenvirales.

[1] SIFV has a linear double-stranded DNA genome of 40,852 bp, which is the largest among characterized lipothrixviruses.

Binding of the major capsid protein dimers to the linear dsDNA genome lead to the assembly of nucleocapsids, which are subsequently enveloped intracellularly through an unknown mechanism.

[3] Unlike in the case of some other archaeal viruses (e.g., rudiviruses and turriviruses), the SIFV VAPs have a hexagonal base (i.e., constructed from six triangular facets).

The VAPs can be as large as 220 nm at the base and are constructed from a single SIFV-encoded protein of 89 aa.