Genus: Thamnovirus


Genus: Thamnovirus

Distinguishing features

Huángjiāo virus (HUJV) is the only currently classified thamnovirus. Like striaviruses, but unlike cuevaviruses, ebolaviruses, and marburgviruses, thamnoviruses apparently infect fish (Shi et al., 2018). Like striaviruses, thamnoviruses are notable in that their genomes do not encode obvious surface glycoproteins or VP40 and VP30 homologs. 

Virion

Morphology

Not reported.

Physicochemical and physical properties

Not reported.

Nucleic acid

Virions are assumed to contain one or several copies of linear negative-sense RNA genomes that are encapsidated independently.

Proteins

Thamnoviruses likely express at least 6 proteins, of which at least two (NP and L) are homologs of proteins expressed by other filoviruses. The second most abundant structural protein in a thamnovirion is assumed to be the nucleoprotein (NP), which encapsidates the striavirus genome. The least abundant protein is assumed to be the RNA-dependent RNA polymerase (L), which mediates thamnovirus genome replication and transcription (Shi et al., 2018).

Lipids

Not reported.

Carbohydrates

Not reported. 

Genome organization and replication

The thamnovirus genome has the gene order: 3′- U1-NP-U2-U3-U4-L-5′ with U denoting genes expressing proteins of unknown function (Figure 1.Thamnovirus). The undetermined extragenic sequences at the extreme 3′ (leader) and 5′ (trailer) ends of the genome are assumed to be conserved and partially complementary. The transcriptional initiation and termination (polyadenylation) sites have yet to be identified.

Figure 1.Thamnovirus. Schematic representation of the thamnovirus genome organization. Genomes are drawn to scale. Courtesy of Jiro Wada, IRF-Frederick, Fort Detrick, MD, USA.

The replication strategy of thamnoviruses remains to be studied.

Antigenicity

Not reported.

Biology

Thamnoviruses were discovered in 2011 by next generation sequencing of samples taken from greenfin horse-faced filefish (Thamnaconus septentrionalis Günther, 1874) captured by fishing trawlers in the East China Sea (Shi et al., 2018).

Species demarcation criteria

The genus currently includes only a single species.

Member species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Huangjiao thamnovirusHuángjiāo virus; Wēnlǐng thamnaconus septentrionalisHuángjiāo virus/T.septentrionalis-wt/CHN/2018/LQMMTII17328MG599981Complete coding genomeHUJV

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.

Derivation of names

Thamnovirus: from Thamnaconus septentrionalis, the fish species to which the presumed host of HUJV, greenfin horse-faced filefish, has been assigned (Shi et al., 2018).