Production of a falcon herpesvirus vaccine

Ten common kestrels (Falco tinnunculus) were used for this falcon herpes va ccine experiment. Four kestrels were subcutaneously given 1 mi of an attenu ated falcon herpesvirus that had originally been isolated from the liver of an American prairie falcon (Falco mexicanus). This virus was then passaged 100 times on chicken embryo fibroblast cells (CEF-cells). Another 4 kestre ls were given subcutaneously an inactivated falcon herpesvirus vaccine deri ved from the same American field strain. This vaccine was concentrated, ina ctivated by heat and betapropiolactone and emulsified in complete Freund's adjuvans. Two further kestrels served as controls and were not vaccinated. Twenty-one days after vaccination, all 10 kestrels were challenged with pas sage 3 of the American falcon herpesvirus. The 2 control kestrels died 6 da ys after challenge and 3 of those given the inactivated herpes vaccine died 9 days after challenge, with typical lesions of herpesvirus inclusion body hepatitis. Before the vaccination experiment, all 10 kestrels were free of serum neutralising antibodies to the falcon herpesvirus. Twenty-one days after vaccination, all 4 kestrels vaccinated with the atten uated vaccine, and one vaccinated with the killed vaccine, had seroconverte d, having shown no symptoms to the challenge with a low passage virulent Am erican herpesvirus strain. Following the challenge their antibody titres to falcon herpesvirus increased. No herpesvirus was isolated from any of the cloacal swabs taken during this experiment, indicating that there is no dan ger for any other birds from the attenuated herpesvirus vaccine. This experiment clearly shows that an attenuated falcon herpesvirus vaccine can protect kestrels from fatal inclusion body hepatitis.