SEROTYPE IDENTIFICATION OF AUSTRALIAN BLUETONGUE VIRUSES USING A RAPID FLUORESCENCE INHIBITION TEST

Rapid serotyping of bluetongue virus (BTV) isolates is required to fac ilitate the choice of an appropriate serotype-specific vaccine in a di sease situation or to improve surveillance of BTV serotype prevalence. Th's communication describes the development and validation of a blue tongue virus fluorescent inhibition test (BTV FIT) as a rapid method t o serotype Australian BTV isolates. The BTV FIT uses virus neutralisat ion principles similar to those used in the rabies rapid fluorescent f ocus inhibition test. The BTV FIT has the ability to provide an accura te serotype identification within 24 h thereby abbreviating the seroty ping process by 3-4 days relative to conventional virus neutralisation assays and making the BTV FIT comparable time-wise with the polymeras e chain reaction technique. The development of the BTV FIT is describe d using BTV reference viruses which have been isolated in Australia, a nd validation of the assay by assessment of five Australian BTV isolat es of unknown serotype by comparison with the plaque inhibition method . The use of the BTV FIT readily facilitated rapid and accurate seroty pe identification of Australian BTV reference viruses and five unknown BTV isolates with results indicating full agreement with the plaque i nhibition method.