The encephalitogenicity of the Hempt vaccine.

The encephalitogenic property of rabies vaccines of brain tissue origin (Hempt vaccine produced in different institutes, Semple vaccine, International Standard of Rabies Vaccine) was studied in animal experiments. Guinea pigs inoculated with the vaccines in complete Freund adjuvant were observed for clinical signs and histopathological changes characteristic of experimental allergic encephalomyelitis. Normal sheep brain suspension was used as control. The minimal encephalitogenic dose of the Hempt vaccine was found about 3,500 times more than that of the control material. Hempt vaccine proved much less reactogenic than the International Standard of Rabies Vaccine and the Semple vaccine. Subsequent lots of Hempt vaccine were slightly different in respect of their encephalitogenic activity.