The ulcus-syndrome in cod (Gadus morhua). IV. Transmission experiments with two viruses isolated from cod and Vibrio anguillarum.

Vibrio anguillarum is a serious fish pathogenic bacterium, but it was not found capable of producing the ulcus-syndrome by different inoculation methods in cod. It was possible to transmit the ulcus-syndrome from cod with the papulo-vesicular stage to apparently healthy cod, when they were kept in the same aquarium. Scarification and inoculation with ground papule material lead to development of the ulcus-syndrome. Inoculation of rhabdovirus failed to produce the ulcus-syndrome. Intracardial inoculation of an icosahedral virus suspension could produce the initial papulo-vesicular stage of the ulcus-syndrome in 13 out of 57 inoculated cod (23%). In another experiment 8 out of 36 (22%) inoculated cod developed the ulcus-syndrome and 1 out of 24 (4%) in the control group developed the ulcus-syndrome. In a third experiment 20 inoculated cod failed to develop the ulcus-syndrome. In a number of other cases where the icosahedral virus probably was present in the inoculation material the ulcus-syndrome was also produced, but with a lower frequency. It is indicated, that the isolated icosahedral virus plays a role in the pathogenesis of the ulcus-syndrome in cod, and that Vibrio anguillarum is important for the further progress of the disease.