CLINICAL, VIROLOGICAL AND IMMUNE-RESPONSES OF NORMAL AND IMMUNOSUPPRESSED DONKEYS (EQUUS-ASINUS AFRICANUS) AFTER INOCULATION WITH AFRICAN HORSE SICKNESS VIRUS

To elucidate the role that donkeys may play in African horse sickness virus (AHSV) persistence during inter-epizootic periods we looked for clinical signs of infection and studied the viraemia and neutralising antibody kinetics in 3 immunocompetent and 3 immunosuppressed donkeys inoculated with AHSV-4. None of the donkeys developed signs of AHS. Ho wever infectious AHSV was isolated from the blood of the immunocompete nt donkeys for up to 17 days post infection (dpi) and viral antigens w ere detected for up to 28 dpi. Immune cells also increased significant ly from 35 to 60 dpi. There was no evidence of a recrudescence of vira emia following immunosuppression of these donkeys at 90 dpi despite a decrease in the numbers of immune cells. Infectious virus was not isol ated from the blood of donkeys that had been immunosuppressed, prior t o AHSV inoculation. However viral antigens were detected for up to 35 dpi. The titres of AHSV-specific neutralising antibodies and the numbe r of immune cells were also significantly lower than in immunocompeten t animals. Our findings suggest that donkeys may be able to play a rol e in the epidemiology of AHS but the ability of vectors to become infe cted by feeding upon viraemic donkeys needs to be assessed before the significance of that role can be fully understood.