The protection of rabbits against the herpesvirus of malignant catarrhal fever by inactivated vaccines.

Cell-free virulent malignant catarrhal fever virus inactivated by either formalin or acetylethylenimine (AEI) and administered with Freund's complete adjuvant protected rabbits against two consecutive parenteral challenges with cell-free virus. However 'protected' rabbits succumbed within 20 days to later inoculation of infected rabbit lymph node suspensions. Both inactivated vaccines evoked high titres of neutralising and immunofluorescent antibody, but more of the rabbits given the AEI preparation showed pyrexia after the first challenge with cell-free virus. The degree of protection afforded was compared with that induced by inactivated antigens of other herpesviruses which cause lymphoproliferative disorders