Duration of bluetongue viraemia and serological responses in experimentally infected European breeds of sheep and goats

The duration of viraemia and the serological responses were studied in two breeds of sheep and two breeds of goats, experimentally infected with bluet ongue (BT) virus serotype 4. Viraemia, detectable by cell culture and embry onated chicken egg inoculation, lasted from the third to sixth day until th e 27th-54th day post infection (p.i.). Significant differences between shee p and goats were not recorded. Lesbos sheep and goats together appeared to have significantly longer viraemias (n = 9, mean 41.3 days) than east-Fries ian sheep and Saanen goats (n = 10, mean 30.4 days, p = 0.0039). Serologica l response was studied by competitive ELISA (c-ELISA) and agar gel immunodi ffusion (AGID) tests. The c-ELISA was more sensitive in detecting BT virus antibodies in all animals than the AGID tests. No significant differences w ere observed between sheep and goats or between breeds. The epidemiological significance of subclinical infection and the extended BT virus viraemias in Lesbos sheep and goats, in relation to the maintenance of the virus and to overwintering is discussed. (C) 1999 Elsevier Science B.V. All rights re served.