Broom AK, Wallace MJ, Mackenzie JS, Smith DW, Hall RA
           Department of Microbiology, University of Western Australia, QEII
           Medical Centre, Nedlands, Perth, Western Australia.
           [email protected]
           J Med Virol 2000 Jun;61(2):259-65

        In northwestern Australia, the flavivirus Murray Valley encephalitis
        (MVE) poses a significant health risk to infants in some aboriginal
        communities, particularly during each wet season. While there are too
        few cases to warrant the development of a vaccine against MVE, a safe,
        effective prophylaxis for these children is still urgently required. The
        use of passive transfer of human gamma globulin to MVE or immunisation
        with a vaccine to the closely related Japanese encephalitis (JE) virus
        were investigated as potential strategies. When 40 microg of IgG was
        purified from MVE-immune human sera and transferred to 3-week-old mice,
        the animals were protected from lethal IP inoculation with MVE virus
        while still producing a detectable immune response to the virus.
        Similarly, sera from adult mice infected sublethally with MVE or JE
        virus provided significant protection against MVE infection. However,
        sera from mice sublethally infected with the related Kunjin or immunised
        with the inactivated JE vaccine (Biken) provided no protection against
        MVE challenge. In fact, mice immunised passively with the latter
        appeared to succumb to MVE challenge more rapidly than mice that
        received serum from unimmunised animals, suggesting that antibody to the
        vaccine had accelerated the progression of disease. These preliminary
        trials in mice indicate that passive immunisation with human gamma
        globulin has the greatest potential as a strategy for MVE prophylaxis,
        whilst the apparent enhancement of MVE by antibodies to the JE vaccine
        requires further investigation, with particular reference to current
        vaccination programs in areas of Australia and Papua New Guinea, where
        both JE and MVE occur.      Copyright 2000 Wiley-Liss, Inc.