Five lots of a mixed live vaccine were prepared tentatively from theexisting commercial hog cholera (HC) live vaccine and swine erysipelas (SE) live vaccine by the freeze-drying method. Each of them contained a HC virus titer of 10
2.7-10
3.8TCID
50/ml and a viable SE bacterial count of 3.1-9.0×10
8cells/ml. Such titer and count were hardly reduced during a storage at 4°C for 15months. Three-week-old mice inoculated intraperitoneally with 1ml of the mixed vaccine and pigs subcutaneously with 10-20ml withstood infection. Pigs inoculated subcutaneously with 1ml of the mixed vaccine withstood challenge inoculation with high virulent HC virus 2weeks later, and with high virulent SE bacilli 3-10 weeks later. In them, HC neutralizing antibody began to be detected 2-3weeks later and viable SE bacteriaagglutinating antibody 1 week later. The former retained a titer of 32-256 and the latter a titer of 16-32 even 6 months later. Pigs inoculated with the mixed vaccine in a field trial presented no abnormal signs at all. When examined a month after inoculation, 93.7% of them showed an increase in titer of HC neutralizing antibody and viable SE bacteria-agglutinating antibody, the former ranging from 32 to 256 and the latter from 16 to 128. These results seem to indicate that the mixed vaccine may be available for practical field use.
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