Arch Virol (2005) 150: 2347–2355
Variation in the coat protein sequence of British isolates
of Turnip yellow mosaic virus and comparison
with previously published isolates
E. J. Mitchell and J. M. Bond
Centre for Ecology and Hydrology Dorset, Winfrith Technology Centre,
Received January 7, 2005; accepted May 24, 2005
Published online August 1, 2005
Summary. Isolates of Turnip yellow mosaic virus (TYMV) were collected from
wild cabbage (Brassica oleracea) on a 400 m stretch of Dorset coastline.
The coat protein genes of four isolates showed high homology in nucleotide
sequence (0.970–1.000, mean 0.987). Lower levels of homology where found to
previously published sequences of Australian isolates  (0.725–0.775, mean
The amino acid composition of the Dorset isolates showed high levels of ho-
mology (0.964–1.000, mean 0.986). Numerous amino acid substitutions occurred
between the Dorset and Australian isolates (0.705–0.819, mean 0.742).
Comparison with other isolates showed large genetic distances between the
Dorset isolates and both European and Australian isolates.
Turnip yellow mosaic virus (TYMV) is a member of the genus Tymovirus which
infects a wide range of Brassica and non-Brassica hosts in northwest Eurasia
and Australia . TYMV has isometric particles of approximately 30 nm in
diameter containing a 6.3 Kb single stranded RNA genome. The genome contains
three overlapping reading frames which encode a 206 K replicase protein, 69 K
movement protein and a 20 K coat protein .
The coat protein of TYMV has been shown to play an important role in the
pathogenicity and virulence of TYMV by affecting the systemic movement of
the virus within its host . Therefore variation in the coat protein gene and the
resulting changes in capsid protein composition between isolates may well be
indicators of differences in the pathology and ecology of individual isolates.