ICTV Virus Taxonomy Profile: Sphaerolipoviridae 2023

Abstract

Members of the family Sphaerolipoviridae have non-enveloped tailless icosahedral virions with a protein-rich internal lipid membrane. The genome is a linear double-stranded DNA of about 30 kbp with inverted terminal repeats and terminal proteins. The capsid has a pseudo triangulation T=28 dextro symmetry and is built of two major capsid protein types. Spike complexes decorate fivefold vertices. Sphaerolipoviruses have a narrow host range and a lytic life cycle, infecting haloarchaea in the class Halobacteria (phylum Euryarchaeota). This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Sphaerolipoviridae, which is available at ictv.global/report/sphaerolipoviridae.

Keywords: ICTV Report; Sphaerolipoviridae; Taxonomy.

Fig. 1.. Morphology of Haloarcula californiae icosahedral virus 1 virion. (a) Cryo-electron micrograph of virions, scale bar: 50 nm, credit: Nicola Abrescia lab, CICbioGUNE, Spain. (b) Schematic model, modified from [6].

Fig. 2.. Genomes of sphaerolipoviruses. HCIV-1, Haloarcula californiae icosahedral virus 1 (31 314 bp, KT809302); SH1 virus, (30 889 bp, AY950802); PH1 virus, (28 072 bp, KC252997); HHIV-2, Haloarcula hispanica icosahedral virus 2 (30 578 bp, JN968479). ORFs/genes are shown as arrows. Homologous genes encoding structural proteins are highlighted with the same colours. Putative spike protein genes are marked with asterisks and ORFs encoding putative spike complex proteins are outlined with blue. Similarities between the genomes are shown as shadings of grey (direct) and brown (inverted). The figure was produced using Easyfig v.2.2.2 with the E-value threshold of 0.001.