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AN ATTENUATED MUTANT OF JAPANESE ENCEPHALITIS VIRUS

Y K INOUE

    Bulletin of the World Health Organization
    |January 1, 1964
    PubMed

    Insights

    An attenuated Japanese encephalitis virus mutant shows stable low virulence in tissue culture and induces high immunity in mice. However, potential reversion to virulence necessitates further genetic stability studies before human vaccine trials.

    Area of Science:

    • Virology
    • Vaccinology
    • Immunology

    Background:

    • Japanese encephalitis virus (JEV) poses a significant public health threat, necessitating effective vaccine development.
    • Live, attenuated vaccines are a promising strategy for JEV prevention.
    • Understanding viral attenuation and genetic stability is crucial for vaccine safety.

    Purpose of the Study:

    • To develop a live, attenuated Japanese encephalitis vaccine.
    • To characterize an attenuated JEV mutant (m mutant) for its potential use in vaccine preparation.
    • To assess the safety and immunogenicity of the m mutant.

    Main Methods:

    • Serial passages of the parental Mukai strain of JEV in embryonic mouse skin cultures to generate an attenuated mutant.
    • Evaluation of the m mutant's virulence in tissue culture and mouse brain.
    • Assessment of the m mutant's immunogenicity in mice following a single intraperitoneal injection.
    • Determination of virus yield in tissue culture.

    Main Results:

    • An attenuated JEV mutant (m mutant) was successfully isolated.
    • The m mutant demonstrated stable low virulence in tissue culture but showed reversion to virulence in mouse brain.
    • A single intraperitoneal injection of the m mutant induced high immunity in mice.
    • High virus yields (approx. 10(9.5) TCD(50)/ml) were obtained from the m mutant in tissue culture.

    Conclusions:

    • The m mutant shows potential for developing an inactivated tissue culture vaccine due to its high virus yield and immunogenicity.
    • Further research into the genetic stability of the m mutant is required before considering human trials.
    • The m mutant's reversion to virulence in vivo highlights the importance of rigorous safety assessments for live attenuated vaccines.
    Keywords:
    ENCEPHALITIS VIRUSESENCEPHALITIS, JAPANESE BEXPERIMENTAL LAB STUDYHAMSTERSMICEMONKEYSSWINETISSUE CULTUREVACCINES

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