The Pleolipoviridae ( pleolipoviruses ) are a family of pseudo-spherical and pleomorphic DNA viruses, the genome of which is partly double-stranded and partly single-stranded: there are circular ssDNA, circular dsDNA or linear dsDNA. According to the Baltimore classification, the Pleolipoviridae cannot therefore be assigned unambiguously to one of the two groups 1 or 2 in their entirety; this also applies in part to individual species themselves. The diameter of the virus particles (virions) is typically 40 to 70 nm a membrane vesicle which encloses various types of DNA genomes with a length of 7 to typically 10, a maximum of 16 kb ( kilonucleotides ). The genome encodes 8 to 16 open reading frames (ORFs). The Pleolipoviridae each have a narrowly defined host range; their natural hosts are salt-loving (halophilic) archaea of the genera Halorubrum , Haloarcula and Halogeometricum in the class Halobacteria (Haloarchaeen), Phylum (division) Euryarchaeota .
The name Pleo-lipo comes from the Greek πλειο-λιπος (much-bold) and refers to the pleomorphic virion and the presence of an envelope.
Propagation cycle
Little is known about the reproduction cycle of the Pleolipoviridae so far. It is non- lytic . Typically, the virions contain a single type of spike protein on the envelope and a single type of internal membrane protein (embedded in the envelope). After the virion attaches to the host cell, the DNA genome invades the host's cytoplasm. It is assumed that the ssDNA is then first converted into dsDNA. Viral mRNA and ribosomes from the host are used for translation . Presumably the dsDNA genome is transcribed by the host's RNA polymerase . The genome replication possibly happens in the 'rolling circle', i.e. all around in a circle. Finally, the daughter virions are composed and released.
Systematics
Three genera are officially recognized by the International Committee on Taxonomy of Viruses (ICTV) (as of November 2018): Alpha , Beta and Gammapleolipovirus , which result from the division of the only earlier genus, pleolipovirus .
