Arch Virol (1999) 144: 561–576
A comparison of six cypovirus isolates by cross-hybridisation
of their dsRNA genome segments
P. P. C. Mertens
, S. Pedley
, R. Rubinstein
, and C. C. Payne
Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, U.K.
Horticulture Research International, Wellesbourne, Warwick, U.K.
Medical School, University of Cape Town, Cape Town, South Africa
Accepted August 14, 1998
Summary. Genetic relationships between the genome segments of six cypovirus
(CPV) isolates were analysed by RNA cross-hybridisation. These included three
type 1 viruses and single isolates of types 2, 5 and 12, which collectively are
identical to those previously compared by serology and electrophoresis [Mertens
et al. (1989), J Gen Virol 70: 173–185]. Since only genome segment 10 of three
cypovirus types and segments 8 and 9 of a single virus strain (of type 1) have
currently been sequenced, this initial study provides some additional information
on sequence variation / similarity in each of the ten genome segments.TheRNA of
the type 1 viruses showed high levels of cross-hybridisation. Signiﬁcant but much
lower levels of cross-hybridisation were detected between type 1 and the related
type 12 CPV. However, only very low levels of cross-hybridisation were detected
between the other pairs of viruses. Apart from evidenceofaslightlyhigherlevel of
sequence similarity between the largest segments, the RNA sequence appeared
to vary uniformly across the whole genome. There was no evidence for any
type speciﬁc RNA sequences restricted to individual genome segment(s). The
sequence variation, reﬂected in the levels of RNA sequence similarity and cross
hybridisation, correlates well with serological data, showing large differences
between CPV types and supports the continued use of electropherotype as one of
the ‘species parameters’ for the classiﬁcation of cypoviruses.
Present address: Robens Centre for Public and Environmental Health, University of
Surrey, Guildford, Surrey, U.K.