Family: Potyviridae

Genus: Macluravirus

 

Distinguishing features

Macluraviruses resemble members of the genus Potyvirus in their transmission by aphids but virions are slightly shorter. Macluravirus genome structure is distinguished by (1) a shorter genome by the absence of P1 protein-coding region and a shorter HC-Pro; and (2) the absence of the aphid-transmission motif DAG in CP region (Kondo and Fujita 2012). Macluraviruses form a distinct group in phylogenetic analyses and have different polyprotein consensus cleavage sites.

Virion

Morphology

Virions are flexuous filaments mostly 650–675 nm×13–16 nm.

Physicochemical and physical properties

Virion Sedimentation coefficient S20,w is 155–158S; density in CsCl is 1.31–1.33 g cm−3.

Nucleic acid

Virions contain one molecule of linear positive-sense, ssRNA of about 8.0 kb.

Proteins

Macluraviruses have a single coat (capsid) protein (CP) of 33–34 kDa.

Genome organization and replication

The complete genome sequences of eight different macluraviruses are available. The aa sequences of macluravirus CPs show limited (14–23%) identity with CP sequences of some aphid-transmitted potyviruses. Macluraviruses show significant aa sequence identity in portions of the replicase protein with viruses in other genera of the family Potyviridae. The macluraviruses seem to have a genome organization and replication strategy typical of viruses in the family Potyviridae (Figure 2.Potyviridae), except that they lack the P1 coding region (Figure 1.Macluravirus). 

Genome diagram Macluravirus
Figure 1.MacluravirusSchematic diagram of the Chinese yam necrotic mosaic virus (CYNMV) genome. The polyprotein ORF is indicated by the large open box divided into putative mature proteins. The pretty interesting Potyviridae protein (PIPO) is represented by a small box. The untranslated regions (UTR) are represented by lines on each end of the large ORF. Activities of mature proteins are postulated by analogy with genus Potyvirus. Conventions are as for the potyvirus genome organization map (Figure 2.Potyviridae). CYNMV lacks a P1 cistron and has a shorter HC-Pro cistron than most potyviruses. Not to scale.

Biology

Host range

Current information suggests that most viruses have a narrow host range, infecting species in up to nine host families.

Transmission

The viruses are transmitted by aphids in a non-persistent manner and experimentally by mechanical inoculation.

Antigenicity

Moderately immunogenic. No serological relationships to members of the genus Potyvirus have been found except for a weak reaction between maclura mosaic virus and bean yellow mosaic virus.

Species demarcation criteria

See discussion under family description.

Related, unclassified viruses

Virus name

Accession number

Virus abbreviation

large cardamom chirke virus

JN257715*

 LCCV

Virus names and virus abbreviations are not official ICTV designations. 

* incomplete genome sequence