Family: Phasmaviridae

Jens H. Kuhn and Holly R. Hughes

The citation for this ICTV Report chapter is the summary published as Kuhn et al. (2024):

ICTV Virus Taxonomy Profile: Phasmaviridae 2024, Journal of General Virology (2024) 105: 002002

Corresponding author: Holly R. Hughes (LTR8@cdc.gov)
Edited by: Holly R. Hughes and Evelien Adriaenssens 
Posted: May 2024

Summary

Phasmaviridae is a family for negative-sense RNA viruses with genomes of about 9.7–15.8 kb (Table 1 Phasmaviridae). The family includes seven genera (Cicadellivirus, Feravirus, Hymovirus, Jonvirus, Orthophasmavirus, Sawastrivirus, and Wuhivirus). These viruses are maintained in and/or transmitted by blattodean, coleopteran, dipteran, hemipteran, hymenopteran, neuropteran, and odonatan insects. Phasmavirids produce enveloped virions containing three single-stranded RNA segments with open reading frames (ORFs) that encode a nucleoprotein (N), a glycoprotein precursor (GPC), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain.

Table 1 Phasmaviridae. Characteristics of members of the family Phasmaviridae.

Viruses assigned to each of the seven genera form a monophyletic clade based on phylogenetic analysis of L protein/RdRP sequences. Viruses from all seven genera share one or more of the following characteristics: (i) enveloped spherical, pleomorphic, or tubular virions; (ii) tri-segmented negative-sense RNA genome; (iii) genomic sequence complementarity at the 5′- and 3′-ends; and (iv) capped but not polyadenylated virus mRNAs. All genera have insect hosts (Table 2 Phasmaviridae).

Table 2. Phasmaviridae. Insect hosts of phasmavirid genera.

Virion

Morphology

Only known for members of the genera Feravirus and Jonvirus (see Feravirus and Jonvirus genus pages).

Physicochemical and physical properties

Only known for members of the genera Feravirus and Jonvirus (see Feravirus and Jonvirus genus pages).

Nucleic acid

Phasmavirids have tri-segmented negative-sense RNA genomes (small [S], medium [M], and large [L] segments) (Table 3 Phasmaviridae). Viral mRNAs are not polyadenylated and contain a 5′-methylated cap and several non-templated nucleotides at the 5′-end that are derived from host cell mRNAs via cap-snatching.

Table 3 Phasmaviridae. Viral RNA segments of typical genus members

Proteins

Phasmavirids typically express three structural proteins. The most abundant structural protein in a phasmavirion is N, which encapsidates the phasmavirid genomic segments. The least abundant is the L protein, which mediates viral genome replication and transcription. Two glycoprotein subunits, G_N and G_C, are produced from GPC and mediate cell entry of phasmavirions (Marklewitz et al., 2015).

Lipids

Likely derived from the Golgi apparatus and/or the host cell plasma membrane and therefore likely composed of phospholipids, glycolipids, fatty acids, and sterols.

Carbohydrates

Only known for members of the genera Feravirus and Jonvirus (see Feravirus and Jonvirus genus pages).

Genome organization and replication

The S RNA encodes N and in some viruses a nonstructural protein (NSs) and/or another protein of unknown function. The M RNA encodes GPC and in some viruses a nonstructural protein (NSm). The L RNA encodes L protein with its RdRP, helicase, and endonuclease domains (Marklewitz et al., 2015, Käfer et al., 2019) (Figure 1 Phasmaviridae).

Figure 1 Phasmaviridae. Genome organization of representative phasmavirids. The 5′- and 3′- ends of all segments are complementary at their termini, likely promoting the formation of panhandle RNP complexes within the virion. GPC, glycoprotein precursor gene; L, large (protein) gene; N, nucleoprotein gene.

Biology

Classified phasmavirids are maintained in and/or transmitted by blattodean, coleopteran, dipteran, hemipteran, hymenopteran, neuropteran, and odonatan insects in Africa, Asia, Europe, Northern America, and South America (da Silva Ferreira et al., 2020, Ottati et al., 2020, da Silva Neves et al., 2021, He et al., 2021, Hermanns et al., 2023, Starchevskaya et al., 2023, Yang et al., 2023, Ballinger et al., 2014, Li et al., 2015, Marklewitz et al., 2015, Schoonvaere et al., 2016, Shi et al., 2016, Makhsous et al., 2017, Shi et al., 2017, Käfer et al., 2019, Öhlund et al., 2019, Batson et al., 2021, Hermanns et al., 2023). Putative phasmavirids have been associated with these insects and branchiopods, collembolan hexapods, myriapods, zorapteran insects, as well as in eulipotyphla, mammals, plants, and fungi in Asia, Europe, Northern America, and Oceania (Li et al., 2015, Käfer et al., 2019, Kobayashi et al., 2020, Lay et al., 2020, Dou et al., 2021, Chen et al., 2022, French et al., 2023, Dong et al., 2024, Medd et al., 2018, Wallace et al., 2021, Tian et al., 2022, Truong Nguyen et al., 2022, Zhang et al., 2022, Litov et al., 2023, Matsumura et al., 2024).

Derivation of names

aedis: after host genus Aedes 
anophelae: after host genus Anopheles 
bastukasense: after Lithuanian Barstukas, a mythical dragon-like creature; the suffix “ense” is incorrectly used and will be corrected 
chrysis: after host genus Chrysis 
chrysurae: after host genus Chrysura 
Cicadellivirus: after host family Cicadellidae 
coleopterus: after host order Coleoptera 
coredoense: after Coredo, Italy 
culicis: after host genus Culex 
eboris: after the Latin ebur, meaning ivory, a reference to Côte d'Ivoire, where jonchet virus was discovered 
ferakinum: after Ferak, the name of a female cartoon character belonging to a botanically-bred race of plant people 
Feravirus: after Ferak virus 
flenense: after Flen, Sweden 
fushunense: after Fǔshùn (< face="Microsoft JhengHei, sans-serif" size="3">抚顺市), China 
gandaense: after Ganda, the Latin name for Ghent, Belgium 
guaguaense: after Guagua, Colombia 
hemipterus: after host order Hemiptera 
hubeiense: after Húběi Province (< face="MS Gothic" size="3">湖北省), China 
Hymovirus: after host order Hymenoptera 
insecti: after the Latin insectum, meaning insect 
Jonvirus: after jonchet virus 
kigluaikense: after the Kigluaik mountains, USA 
miglotasense: after Lithuanian miglotas, meaning obscure, foggy, misty. The suffix “ense” is incorrectly used and will be corrected 
neuropterus: after the host order Neuroptera 
niuklukense: after Niukluk River, USA 
odonatus: after host order Odonata 
Orthophasmavirus: from the Ancient Greek ὀρθός (orthós), meaning straight, right, proper, and phantom midges, host of the first described viruses of the family 
Phasmaviridae: after phantom midges, hosts of the first described viruses of the family 
philoctetis: after host genus Philoctetes 
sanxiaense: after Sānxiá (< face="MS Gothic" size="3">三峡), China 
Sawastrivirus: after Sānxiá water strider virus 
scaphoidei: after host genus Scaphoideus 
sogatellae: after host genus Sogatella 
wuchangense: after Wǔchāng (< face="MS Gothic" size="3">武昌), China 
wuhanense: after Wǔhàn (< face="MS Gothic" size="3">武< face="Microsoft JhengHei, sans-serif" size="3">汉), China 
Wuhivirus: after Wǔhàn insect virus 2

Genus and species demarcation criteria

The availability of at least coding-complete sequences of all three genome segments may be sufficient for phasmavirid classification in the absence of a cultured isolate. Viruses within the same genus form a monophyletic clade separate from those of other phasmavirid genera. The phasmavirid species demarcation criterion is <95% identity in the amino acid sequence of the L protein.

Relationships within the family

Phylogenetic relationships across the family have been estimated using phylogenetic trees generated from complete L amino acid sequences. The family is divided into two major clades: one including the genera Cicadellivirus and Orthoplasmavirus, and the other including the genera Feravirus, Hymovirus, Jonvirus, Sawastrivirus, and Wuhivirus (Figure 2 Phasmaviridae).

Figure 2 Phasmaviridae. Phylogenetic analysis of phasmavirid L protein sequences. Publicly available coding-complete phasmavirid genomes were downloaded from NCBI GenBank. Coding sequences of the L segment were codon-aligned using Clustal W (Mega v10). The resulting amino acid sequences were used for phylogenetic inference by producing a neighbor-joining tree with a Poisson correction and a gamma distribution of variation between sites in MEGA7. Branches with <70% bootstrap support are not labeled.

Relationships with other taxa

Phasmavirids are closely related to ellioviral crulivirids, fimovirids, hantavirids, peribunyavirids, tulasvirids, and tospovirids (Wolf et al., 2018, Herath et al., 2020, Olendraite et al., 2023).

Related, unclassified viruses

*incomplete sequence

Virus names and virus abbreviations are not official ICTV designations.

Additional unclassified phasmavirids that are probable members of established genera are listed under individual genus descriptions.