''Portogloboviridae'' is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of dsDNA viruses that infect

archaea Archaea ( ) is a Domain (biology), domain of organisms. Traditionally, Archaea only included its Prokaryote, prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even thou ...

. It is a proposed family of the

realm A realm is a community or territory over which a sovereign rules. The term is commonly used to describe a monarchical or dynastic state. A realm may also be a subdivision within an empire, if it has its own monarch, e.g. the German Empire. Etymo ...

Varidnaviria ''Varidnaviria'' is a realm of viruses that includes all DNA viruses that encode major capsid proteins that contain two vertical jelly roll folds. The major capsid proteins (MCP) form into pseudohexameric subunits of the viral capsid, which s ...

'', but ICTV officially puts it as

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

virus. Viruses in the family are related to '' Helvetiavirae''. The capsid proteins of these viruses and their characteristics are of evolutionary importance for the origin of the other ''Varidnaviria'' viruses since they seem to retain primordial characters.

Description

The

virion A virion (plural, ''viria'' or ''virions'') is an inert virus particle capable of invading a Cell (biology), cell. Upon entering the cell, the virion disassembles and the genetic material from the virus takes control of the cell infrastructure, t ...

s in this family have a capsid with icosahedral geometry and a

viral envelope A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. A viral envelope protein or E protein is a protein in the en ...

that protects the

genetic material Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nucleic aci ...

. The diameter is 83 to 87 nanometers. The

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

is circular dsDNA with a length of 20,222 base pairs. The

contains 45 open reading frames (ORFs), which are closely arranged and occupy 89.1% of the genome. ORFs are generally short, with an average length of 103

codon Genetic code is a set of rules used by living cells to translate information encoded within genetic material (DNA or RNA sequences of nucleotide triplets or codons) into proteins. Translation is accomplished by the ribosome, which links prote ...

s. Virions have 10

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

ranging from 20 to 32 kDa. Of these proteins, 8 code for the capsid and two for the viral envelope, including one that is a vertical single jelly roll (SJR) capsid protein. Entry into the host cell is by penetration.

Viral replication Viral replication is the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its genome ...

occurs by chronic infection without a

lytic cycle The lytic cycle ( ) is one of the two cycles of viral reproduction (referring to bacterial viruses or bacteriophages), the other being the lysogenic cycle. The lytic cycle results in the destruction of the infected cell and its membrane. Bacter ...

. The ''Portogloboviridae'' viruses together with ''Halopanivirales'' have evolutionary importance in the evolution of the other ''Varidnaviria'' viruses since they appear to be relics of how the first viruses of this realm were. ''Portogloboviridae'' together with ''Halopanivirales'' may have infected the

last universal common ancestor The last universal common ancestor (LUCA) is the hypothesized common ancestral cell from which the three domains of life, the Bacteria, the Archaea, and the Eukarya originated. The cell had a lipid bilayer; it possessed the genetic code a ...

(LUCA) and originated before that organism. It has been proposed that it may be related to the origin of ''Varidnaviria'' in the following way.

Taxonomy

The family has one genus which has two species: * ''Alphaportoglobovirus'' ** ''Alphaportoglobovirus beppuense'' ** ''Alphaportoglobovirus umijigokuense''

References

{{Taxonbar, from=Q54811030 DNA viruses