Kanesa-thasan N, Smucny JJ, Hoke CH, Marks DH, Konishi E, Kurane I, Tang
          DB, Vaughn DW, Mason PW, Shope RE
          Department of Virus Diseases, DCD&I, Walter Reed Army Institute of
          Research, 503 Robert Grant Avenue, MD 20910, Silver Spring, USA
          Vaccine 2000 Oct 15;19(4-5):483-491

        A controlled, randomized, double-blind clinical trial evaluated whether
        two attenuated recombinant poxviruses with identical Japanese
        encephalitis virus (JEV) gene insertions, NYVAC-JEV and ALVAC-JEV, were
        safe and immunogenic in volunteers. Groups of 10 volunteers
        distinguished by vaccinia immune status received two doses of each
        vaccine. The vaccines appeared to be equally safe and well tolerated in
        volunteers, but more reactogenic than licensed formalin-inactivated JE
        and placebo vaccines given as controls. NYVAC-JEV and ALVAC-JEV vaccine
        recipients had frequent occurrence of local warmth, erythema,
        tenderness, and/or arm pain after vaccination. There was no apparent
        effect of vaccinia immune status on frequency or magnitude of local and
        systemic reactions. NYVAC-JEV elicited antibody responses to JEV
        antigens in recipients but ALVAC-JEV vaccine poorly induced antibody
        responses. However, NYVAC-JEV vaccine induced neutralizing antibody
        responses only in vaccinia-nonimmune recipients while vaccinia-immune
        volunteers failed to develop protective antibodies (5/5 vs. 0/5
        seroconversion, p<0.01). These data suggest that preexisting immunity to
        poxvirus vector may suppress antibody responses to recombinant gene
        products.