VIROLOGY DIVISION NEWS
Virgaviridae: a new family of rod-shaped plant viruses
Michael J. Adams
John F. Antoniw
Received: 16 June 2009 / Accepted: 26 August 2009 / Published online: 28 October 2009
Ó Springer-Verlag 2009
Abstract The new plant virus family Virgaviridae is
described. The family is named because its members have
rod-shaped virions (from the Latin virga = rod), and it
includes the genera Furovirus, Hordeivirus, Pecluvirus,
Pomovirus, Tobamovirus and Tobravirus. The chief char-
acteristics of members of the family are presented with
phylogenetic analyses of selected genes to support the
creation of the family. Species demarcation criteria within
the genera are examined and discussed.
The International Committee on Taxonomy of Viruses
(ICTV) has recently approved a proposal to create a plant
virus family Virgaviridae. The family is named because
its members have rod-shaped virions (from the Latin
virga = rod), and it includes the genera Furovirus, Hor-
deivirus, Pecluvirus, Pomovirus, Tobamovirus and Tobra-
virus. The chief characteristics of members of the family
1. Alpha-like replication proteins that form a distinct
phylogenetic ‘‘family’’ .
2. Single-stranded RNA ? sense genomes with a
-t-RNA-like structure and no polyA tail.
3. Rod-shaped virions 20–25 nm in diameter with a
4. Coat proteins of 19–24 kDa.
It contains some viruses in which there is a single cell-
to-cell movement protein (MP) of the ‘30K’ superfamily
 and others that encode a triple gene block (TGB) .
There are also differences in the number of genomic RNAs
(1, 2 or 3 depending on the genus), but sequence analysis of
the polymerase and other genes suggests that the viruses
form a coherent taxonomic unit (see below). Some prop-
erties of the six genera included in the family are sum-
marized in Table 1, and their genome organization is
shown in Fig. 1. Biologically, the viruses are fairly diverse.
They have been reported from a wide range of herbaceous
and mono- and dicotyledonous plant species, but the host
range of individual members is usually limited. All mem-
bers can be transmitted experimentally by mechanical
inoculation, and for those in the genus Tobamovirus, this is
the only known means of transmission. In some genera,
transmission is by soil-borne vectors, while members of the
genus Hordeivirus are transmitted through pollen and seed.
The only genus with rod-shaped virions excluded from this
list is Benyvirus, because this is much more distantly
related in phylogenetic analyses of the polymerase (see
below) and because (unlike the others) its members have a
polyadenylated genome and a polymerase that is processed
by autocatalytic protease activity.
On the basis of their analysis of the RNA-dependent
RNA polymerase (RdRp) gene from a wide range of
viruses, Koonin and Dolja  included viruses from the six
genera described in this paper within RdRp Supergroup 3,
which they sub-divided into three lineages that they sug-
gested might correspond to orders. One of these lineages,
which they named Tobamo, included the six genera
M. J. Adams (&) Á J. F. Antoniw
Department of Plant Pathology and Microbiology,
Rothamsted Research, Harpenden,
Hertfordshire AL5 2JQ, UK
Germplasm Enhancement and Crop Improvement Division,
International Potato Center, Lima, 12, Peru
Arch Virol (2009) 154:1967–1972