Family: Phenuiviridae

Genus: Citricivirus

Distinguishing features

Aphis citricidus bunyavirus (AcBV) is assigned to Citricivirus chongqinense, the only species in the genus. Citricivirus RNA has been found by high-throughput sequencing of RNA from a brown citrus aphid. The citricivirus genome has four genes, encoding a large protein (L), two external glycoproteins (Gn and Gc) and a nucleocapsid protein (N). Based on well-supported Maximum Likelihood or Maximum Clade Credibility trees inferred from complete L protein sequences, viruses classified in the genus Citricivirus form a monophyletic cluster clearly distinguished from other phenuivirids. There currently is no cultured citricivirus isolate (Zhang et al., 2019).

Virion

Morphology

Virion morphology is unknown.

Nucleic acid

Citricivirus genomes encompass three segments of negative-sense RNA: L (7.0 kb), M (3.5 kb) and S (1.2 kb). Analysis of the terminal sequences has yet to be completed. All three genomic RNAs contain untranslated regions flanking a single ORF which, based on comparisons with other negative-sense RNA viruses, is predicted to be contained in the virus-complementary strand. In silico analysis of the citricivirus putative ORF sequences suggests that citricivirus encodes three structural proteins: L with a predicted molecular mass of 253.1 kDa, a glycoprotein precursor (GP) of 112.5 kDa, and N of 31.3 kDa, these protens sharing sequence homology and/or structural characteristics with the cognate proteins of other phenuivirids (Zhang et al., 2019).

Genome organization and replication

The citricivirus genome consists of three negative-sense RNAs (Figure 1 Citricivirus). The citricivirus genome arrangement is similar to that of beidiviruses, goukoviruses, hudiviruses, hudoviruses, phasiviruses, pidchoviruses, and tanzaviruses (Figure 2 Phenuivridae). The L, M and S segments putatively encode L, a glycoprotein precursor (comprising Gn and Gc) and N, respectively. The Gn and Gc glycoproteins were earlier referred to as G1 and G2 based on apparent size on gel electrophoresis, respectively. The citricivirus genome does not encode either of the non-structural proteins NSs or NSm. Details of virus replication are unknown (Zhang et al., 2019).

Figure 1 Citricivirus. Genome organization of a citricivirus. Coloured boxes depict ORFs that encode N, nucleocapsid protein; Gn and Gc, external glycoproteins; and L, large protein.

The only known virus was has been found by high-throughput sequencing of RNA from a pool of brown citrus aphids [Toxoptera citricida (Kirkaldy, 1907)] from Chongqing (重庆市), China (Zhang et al., 2019).

Species demarcation criteria

Not defined as the genus currently includes only a single species.

Related, unclassified viruses

* Sequences do not comprise the complete genome segment.

Virus names and virus abbreviations are not official ICTV designations.