Blood samples were collected regularly from two sentinel herds of cattle in northern and southern Queensland between 1979 and 1985. From 2660 samples, virus isolation attempts using baby hamster kidney (BHK21) and Aedes albopictus (AA) tissue cultures and suckling mice produced 308 viruses of which 243 (79%) were in the Palyam subgroup of orbiviruses. Mosquitoes and biting midges were collected at the southern sentinel herd site in January-February 1984 and processed for virus isolation in BHK2l and AA tissue cultures and by intrathoracic inoculation of Ae. aegypti mosquitoes. Totals of 14 338 midges of four species in 156 pools, and 9030 mosquitoes of 27 species in 232 pools, were processed and yielded 59 isolations. Of the 35 viruses isolated from Culicoides brevitarsis, 17 were members of the Palyam subgroup. Bovine ephemeral fever (BEF) virus was isolated once from Anopheles bancroftii, once from C. brevitarsis and 17 times from cattle. Akabane virus was isolated for the first time from C. wadai, as well as a further 10 times from C. brevitarsis and 20 times from cattle. Other viruses isolated from cattle included bluetongue serotype 1, and serotypes 5, 6 and 7 of epizootic hemorrhagic disease of deer (EHD). A new BEF group virus, tentatively called Oak Vale, was isolated nine times from Culex edwardsi mosquitoes. Of the orbiviruses, those in the Palyam subgroup were isolated almost exclusively in BHK2l tissue cultures but those in the bluetongue and EHD subgroups were isolated almost exclusively in AA cell cultures or after passage through Ae. aegypti. Of 22 rhabdovirus isolations from blood and insects (BEF, Kimberley and Tibrogargan), 16 were made only in AA cell cultures or after passage through Ae. aegypti.
Development of inactivated Akabane and bovine ephemeral fever vaccine for cattle
