INVESTIGATIONS ON COURSE AND OUTCOME OF PHOCINE DISTEMPER VIRUS-INFECTION IN HARBOR SEALS (PHOCA-VITULINA) EXPOSED TO POLYCHLORINATED-BIPHENYLS - VIROLOGICAL AND SEROLOGICAL INVESTIGATIONS

The influence of polychlorinated biphenyls (PCBs) on phocine distemper virus (PDV) infections in harbour seals (Phoca vitulina) was studied. Six out of ten seals had been conditioned with a defined mixture of P CB-congeneres for several weeks. Following exposure to the cell cultur e-propagated PDV isolate 2558/Han 88 the complete clinical picture of "1988 seal plague" was provoked in all ten seals inoculated. Four out of six PCB-conditioned seals and two out of four seals not loaded with PCBs succumbed to the infection within three weeks post inoculation. With regard to the clinical course, duration of cell-associated viremi a, PDV-antigen distribution in tissues of fatally infected seals and t he humoral immune response to PDV no differences between PCB-loaded an d unloaded seals were recognized. Evidence was obtained that the patho genesis of experimental PDV-infection in harbour seals shares some fea tures with those of canine distemper in terrestrial carnivores. In con trast, however, to experimental distemper infection of gnotobiotic dog s prompt development of high titres of PDV-specific IgG did not correl ate with recovery from infection.