Ligamenvirales is an order of viruses that infect archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

 of the kingdom Crenarchaeota

Crenarchaeota

In taxonomy, the Crenarchaeota has been classified as either a phylum of the Archaea kingdom or a kingdom of its own...

 and have double stranded DNA genomes.

The name is derived from the Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word ligamen meaning 'string' or 'thread'.

Taxonomy

There are two families in this order - Lipothrixviridae and Rudiviridae.

The virons are filamentous with a helical nucleocapsid. Both ends of the virons are plugged with a proteinous material. At either end are attached either tail fibers or more complex structures involved in host adhesion.

The major coat protein has an unusual structure shared by both families. Both families also share an unusual gylcosyltransferase. Up to nine genes are common to these families.

The genome is non segmented linear double stranded DNA.

The viral life cycle in both families is lysogenic rather than lytic.