Abstract
The dsRNA profiles of all nine African horsesickness virus (AHSV) serotypes were compared by agarose gel electrophoresis and PAGE. The agarose profiles were identical, but a unique profile was obtained for each of the nine serotypes by PAGE. Nine of the 10 dsRNA genome segments of AHSV-3 were cloned and the clones were used in dot-spot and Northern blot hybridization experiments to determine intra- and inter-serogroup nucleic acid similarities. Segments 1, 3, 4, 5, 7 and 8 were highly conserved in the AHSV serogroup and no genetic relationship with any of the other orbiviruses was observed. Of these segments 3, 5 and 8 showed the largest degree of cross-hybridization to the cognate genes of all the serotypes. These clones did not cross-hybridize to other orbiviruses such as epizootic haemorrhagic disease virus, bluetongue virus or equine encephalosis virus and are therefore recommended for use as group-specific probes for the identification of the AHSV serogroup. Genome segments 6 and 10 showed an intermediate degree of conservation, whereas segment 2 is serotype-specific and therefore probably codes for the outer capsid protein VP2.