S10 segment sequence analysis of some Greek bluetongue virus strains

Sequence analyses of the non-structural protein gene NS3/NS3A of eight Greek bluetongue (BT) virus (BTV) field isolates from the 1979 and 1999-2001 epizootics provide preliminary molecular data on the epidemiology of BT in Greece. These isolates from infected sheep belonged to serotypes BTV-1, BTV-4, BTV-9 and BTV-16. Phylogenetic analysis of the NS3/NS3A gene segregated these Greek isolates of BTV into two monophyletic groups. The first group was formed by all isolates of BTV-4; all were identical in their sequences, regardless of the area and year of isolation in Greece, and clustered with strains from Tunisia and Corsica. The isolates of BTV-1, BTV-9 and BTV-16 segregated into a second monophyletic group and clustered with Asian strains, showing a high homology (97-99%). From an epidemiological point of view, these preliminary results infer that one group of isolates is Mediterranean, whilst the second appears to be of Asian origin.