Dendritic cells presenting equine herpesvirus-1 antigens induce protectiveanti-viral immunity

Equine herpesvirus-1 (EHV-1) causes rhinopneumonitis, abortion and CNS diso rders in horses. Using intranasal inoculation, the mouse model of this dise ase mimics the major pathogenic and clinical features of the equine disease , The aim of this study was to investigate whether murine dendritic cells ( DC) can be infected with EHV-1 and whether they can be used as cellular vac cines for the induction of prophylactic anti-EHV-l immunity. It was found t hat the DC lines FSDC, D2SC1, 18 (all H-2(d)) and 80/1 (H-2(k)), when incub ated with the Ab4 strain of EHV-1, do not change their morphology and pheno type but sustain virus replication and induce proliferation of naive, synge neic T cells. An even stronger proliferation of T cells was seen when DC we re used that had been pre-exposed to heat-inactivated virus. DC lines were therefore pulsed with inactivated virus and were then administered intranas ally to either BALB/c or C3H mice on days -25, -15 and -5. Control groups r eceived either medium, unpulsed DC or inactivated virus only. Animals were challenged with EHV-1. Whereas mice of control panels showed clinical signs of EHV-1 disease and 27 % died, animals immunized with the pulsed DC lines showed only subtle clinical symptoms, lost significantly less weight, exhi bited a reduced virus load in their lungs and CNS and did not succumb to th e disease during the observation period, These results show that murine DC can present EHV-1 and initiate a protective anti-viral immunity in vivo.