[Concentrated purified vaccine against tick-borne encephalitis prepared by means of zonal ultracentrifugation. Development of the preparation].

A concentrated and purified (lyophilized) preparation with a high immunological activity was obtained from formalin-inactivated tissue culture suspensions of tick-borne encephalitis (TBE) virus. Its high immunogenicity was demonstrated in mouse protection tests against fatal challenge with TBE and in the studies of antibody production in monkeys of two species. The preparation was shown to contain no infectious TBE virus, to be safe for small laboratory animals and monkeys. Trials of the preparation in 19 volunteers demonstrated it to be well tolerated and to induce virus-neutralizing antibody production in man. It also sensitized lymphoid cells when inoculated subcutaneously with Al2O3. These experimental materials indicate the possibility of developing a highly potent vaccine against tick-borne encephalitis by concentration and purification of TBE particle suspensions.