Abstract
Summary
Neutralizing antibodies for Japanese B encephalitis virus appeared in significant titers in 4 of 12 students inoculated with 4 to 6 cc of formalin-inactivated, angle-centrifuged, lyophilized mouse brain vaccine. Equivocal titers developed after vaccination in 3 additional members of this group, but intra-abdominal neutralization tests in very young mice gave negative results with these sera. The antibodies which appeared in significant titers persisted for at least 4 weeks. These data suggested that 4 cc of a vaccine, possessing a 50% immunogenic dose in mice of about 0.01 cc, was probably in the range of minimal dosage that would be required for human beings.
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