Type Species

Sweet potato mild mottle virus

(SPMMV)

Virion Properties

Virions are flexuous filaments 800-950 nm long. Virion S_20w is 155S for Sweet potato mild mottle virus (SPMMV). Virions contain a positive sense ssRNA, approximately 10.8 kb in size, with a 3-poly(A) terminus. The viral CP of is a single peptide of 270-275 amino acids. Electrophoretic Mr is 37.7 10³. No lipids or carbohydrates are reported.

Genome Organization and Replication

The complete nucleotide sequence of SPMMV genome consists of 10818 nts excluding the 3-terminal poly(A) tail. Sequence analysis reveals an ORF of 3456 amino acids. The structure and organization of the SPMMV genome appear to be similar to those of other Potyviridae except the bymoviruses. Almost all known potyvirus motifs are present in the polyprotein of SPMMV. However, motifs in the putative HC-Pro and CP of SPMMV are incomplete or missing which may account for its vector relations. Despite these similarities, comparative sequence analyses show only limited similarities between the nine mature proteins and those of other species in the family Potyviridae.

Antigenic Properties

Moderately immunogenic. No serological relationships with other members of the family Potyviridae.

Biological Properties

Inclusion Body Formation

Characteristic cytoplasmic cylindrical (“pinwheel”) inclusions are present in infected cells.

Host Range

The natural host range of SPMMV is wide, with more than nine families susceptible.

Transmission

SPMMV is transmitted by the whitefly Bemisia tabaci in a non-persistent manner and is transmissible experimentally by mechanical inoculation and by grafting.

List of Species Demarcating Criteria in the Genus

Not applicable.

List of Species in the Genus

Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:

Species in the Genus

Sweet potato mild mottle virus

[Z73124]

(SPMMV)

Tentative Species in the Genus

Sweet potato yellow dwarf virus

(SPYDV)