[Comparative analysis of tests on in vitro and in vivo quantitative assessment of the immunogenicity of tick-borne encephalitis vaccine].

Many-year routine use of EIA as an in vitro test demonstrated it as a highly reproducible and technological test for assessing the efficacy of vaccine against tick-borne encephalitis and its semiproducts at the intermediate stages of vaccine production. The reproducibility of mouse protection test is notably inferior to that of EIA.

Immunological basis for protection in a murine model of tick-borne encephalitis by a recombinant adenovirus carrying the gene encoding the NS1 non-structural protein.

The humoral immune response to flaviviruses is mainly directed to the major envelope protein, E, and a glycosylated non-structural protein, NS1. Cell-mediated immune responses, however, appear to be directed mainly against non-structural proteins. Experiments described here show that a defective recombinant adenovirus (Rad51) containing the gene encoding the NS1 protein of tick-borne encephalitis virus can induce a strong protective immune response against several pathogenic tick-borne flaviviruses in an experimental animal model, and can enhance the efficacy of conventional vaccine preparations.

[A recombinant adenovirus expressing the NS1 nonstructural protein of tick-borne encephalitis virus: some characteristics of the immunologic basis of antiviral action].

Recombinant adenovirus expressing NS1 nonstructural protein of trick-borne encephalitis (TBE) virus (Rad 51) protected mice from many strains of TBE and Omsk hemorhagic fever (OHF) viruses, but virtually did not protect them from Negishi virus. During combined use of whole-virion inactivated TBE vaccine and Rad 51 the recombinant adenovirus notably potentiated the protective effect of the traditional vaccine. The results of adaptive transfer of immunological material from mice infected with Rad 51 showed that both the vaccinated animals' sera and the pool of T and B cells partially protected the recipient mice from lethal TBE infection.

Rapid vaccination protocols for commercial vaccines against tick-borne encephalitis.

Although inactivated viral vaccines have been dramatically successful in controlling many of the world's most devastating diseases, they frequently need several injections to ensure high levels of protection, and thus their efficacy is reduced in many situations. We have developed several rapid vaccination protocols for two commercial vaccine preparations against tick-borne encephalitis virus and studied their efficacy in an experimental murine model. Vaccination protocols as brief as two doses given over two days elicit efficient protection against challenge with potentially fatal doses of virus and this protection is afforded as soon as 5 or as long as 100 days after the first vaccination.

[The use of rocket immunoelectrophoresis for determining glycoprotein in concentrated rabies vaccines].

Rocket immunoelectrophoresis (RIE) was shown to be useful for the evaluation of glycoprotein (GP) content in concentrated rabies vaccines, and disintegron B., a zwitterionic detergent made in this country, for treatment of the vaccines for these evaluations. The values of GP content obtained by RIE and single radial immunodiffusion test were similar.

[The protective activity of preparations made from the tick-borne encephalitis virus grown using different cell cultures].

The preparations of tick-borne encephalitis (TBE) virus grown in swine embryo kidney cell culture have been shown to possess pronounced protective activity per unit of virion protein E in comparison with TBE virus preparations derived from cell culture 4647 and chick embryo cell culture. The antigenic activity of all virus preparations under study has proved to be practically the same. The role of post-translation modifications of TBE virus protein E in the manifestation of some of its biological properties is discussed.

Immunogenicity of inactivated purified tissue culture vaccine against hepatitis A (HepAvac) assessed in laboratory rodents.

Immune response of laboratory rodents (guinea-pigs, CBA and Balb/c mice, Wistar and August rats) to inactivated hepatitis A vaccine was quantitatively assessed. Under comparable conditions of experiment, the mice showed the highest antibody titres and were capable of reacting to the lower doses of immunogen; meanwhile their individual variations in immune response were more pronounced; white rats were the least susceptible to the vaccine, demonstrating the minimal antibody formation; guinea-pigs produced antibody at intermediate levels but the antibody titres were the most homogeneous. The enhancing effect of aluminium hydroxide was observed in guinea-pigs examined at the late postimmunization stage.

Immunogenicity trial of inactivated hepatitis A virus vaccine in human volunteers.

An inactivated hepatitis A virus (HAV) vaccine was tested on a group of human adult volunteers. The vaccine was administered subcutaneously, and a control group received a placebo (aluminium hydroxide). The vaccine was found to be relatively well tolerated and non-reactogenic, and levels of anti-HAV were comparable to those in other studies.

[The immunogenicity of a cultured inactivated hepatitis A vaccine].

A trial of inactivated hepatitis A viral vaccine of heteroploid cell culture origin is described. The vaccine preparation was tested in guinea pigs and tamarins. The animals were immunized intramuscularly four or three times, respectively.

Use of protamine sulphate for elimination of substrate DNA in poliovaccines produced on continuous cell lines.

Cell substrate DNA was shown to be an abundant contaminant in the clarified preparations of the Sabin type 1, 2 and 3 poliovaccines produced on a continuous cell line (4647). The size of the DNA, as evaluated for the Sabin type 1 poliovaccine, was highly heterogeneous, ranging from 100 to 20,000 base pairs. In view of potential oncogenicity of this DNA a simple and efficient procedure for its elimination is proposed.

pH-dependent fusion of tick-borne encephalitis virus with artificial membranes.

pH-dependent fusion of TBE virus with artificial membranes was effective at slightly acidic pH with maximum at 6.4. The influence of various changes in E protein conformation on fusion process was studied.

[The process of the pH-dependent fusion of the tick-borne encephalitis virus with artificial membranes].

Fusion of TBE virus with liposomes was distinctly determined at pH 7.0 or lower, the maximum degree of fusion being observed at pH 6.4.

[Immunogenicity and stability of a Soviet inactivated cultured vaccine against Japanese encephalitis].

Six immunologically active vaccine batches inducing a specific antibody to Japanese encephalitis (JE) virus were obtained in serial manufacture of the preparation. In HI tests, the minimal antibody titre was 1:80, the maximal 1:320, neutralization index 1g was 3.7 to 5.

[The purification of tick-borne encephalitis virus preparations of cellular DNA].

According to the WHO requirements, the concentration of cellular DNA in vaccine preparations produced by pooling virus from continuous cell lines is limited to 100 ng/dose. In this study, different methods were used for purification of tick-borne encephalitis virus suspensions grown in continuous cultures of cell line 4647 from cellular DNA. Two approaches are proposed based on treatment with DNAse and promamin sulfate which allow one to reduce cellular DNA concentration in the virus preparation to the acceptable level.

[Changes in biological properties of tick-borne encephalitis virus during cleavage of disulfide bonds in protein E].

The study showed the disruption of disulphide bonds in E protein of tick-borne encephalitis virus (TBE) to lead to the loss of antigenicity, infectivity, hemagglutinating and protective activities. The loss of infectivity under the effect of a thiolic reagent appears to be associated with block of the very first stage of virus-cell interaction, virus adsorption on the target cell. An attempt to reestablish the E protein structure and the above-mentioned virus properties after the removal of the thiolic reagent failed.

[Use of direct solid-phase immunoenzyme analysis for assessing the immunological activity of a vaccine against tick-borne encephalitis].

A high correlation between the current index of the effectiveness of tick-borne encephalitis vaccine, its protective activity in mice, and the results of the direct solid-phase enzyme-immunoassay has been established, which permits the use of this assay as an auxiliary method for the immunological evaluation of newly prepared commercial purified tick-borne-encephalitis vaccine.