[The use of rocket immunoelectrophoresis for determining glycoprotein in concentrated rabies vaccines]. / Primenenie raketnogo immunoélektroforeza dlia opredeleniia glikoproteina v kontsentrirovannykh antirabicheskikh vaktsinakh.

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 highest values were obtained for all the vaccines tested with anti-PM GP serum compared with anti-ERA and Vnukovo-32 GP serum. When anti-PM and anti-Vnukovo-32 GP sera were used for RIE two components were revealed in the vaccines. All the preparations under study contained soluble GP.

[Modifications to a method of controlling the immunogenic activity of rabies vaccines]. / Modifikatsii metoda kontrolia immunogennoi aktivnosti antirabicheskikh vaktsin.

To determine the immunogenic potency of different rabies vaccines, they were tested in the modified test, originally developed by the National Institutes of Health (USA). In this modification the mice used in the test were challenged with strains Vnukovo-32 and Moskva instead of strain CVS, and the vaccine was introduced not in two injections, but in a single injection. The study revealed that the use of test strain Vnukovo-32, homologous to the production vaccine strain, enhanced the absolute potency of vaccines but produced no effect on the relative potency when used with the similarly prepared reference agents. A single injection of the vaccine in the test for immunogenic potency was found to produce no changes in the results of tests for relative immunogenic potency. However, this modification needs further more extensive trials and discussion.

[The efficacy of a cultured rabies vaccine studied in guinea pigs preliminarily infected with a fixed rabies virus]. / Izuchenie éffektivnosti kul'tural'noi antirabicheskoi vaktsiny na morskikh svinkakh v usloviiakh predvaritel'nogo zarazheniia ikh fiksirovannym virusom beshenstva.

In experiments of curative vaccination, carried out with the use of an experimental model similar to the current practice of treatment with antirabies preparations, the advantages of using tissue-culture rabies vaccine with immunogenic potency equal to 1.3 international units (I. U.) were shown. In these experiments the vaccine was introduced into guinea pigs infected with fixed rabies virus, the course of vaccination consisting of 14 daily injections. No correlation between the induction of virus-neutralizing antibodies and the immunogenic potency of tissue-culture rabies vaccine was established: the use of the vaccine with immunogenic potency equal to 0,3 and 1,3 I.U. had no essential influence on the level of antibody formation in the animals.

[The purification and concentration of the rabies virus by a diafiltration concentration method]. / Ochistka i kontsentrirovanie virusa beshenstva metodom diafil'tratsionnogo kontsentrirovaniia.

Purified concentrates of rabies virus were prepared by both microfiltration chromatography and diafiltration methods. The diafiltration concentrate had a high level of protective activity and was not inferior to the microfiltration chromatographic one. The infectious activity was better retained after diafiltration, the chromatographic purity of both preparations was similar. It is concluded that diafiltration presents a good alternative to the currently used methods for purification and concentration of viruses.

[The results of using direct solid-phase immunoenzyme analysis for assessing the specific activity of rabies vaccines]. / Rezul'taty ispol'zovaniia priamogo tverdofaznogo immunofermentnogo analiza dlia otsenki spetsificheskoi aktivnosti antirabicheskikh vaktsin.

The effectiveness of the solid-phase enzyme immunoassay (EIA) in the determination of the specific activity of rabies vaccines is evaluated in comparison with that of the protective test in mice. Inactivated tissue-culture, concentrated tissue-culture and purified cerebral tissue vaccines for human use were studied. The methods for performing two EIA variants and evaluating the results are described. The average level of correlation between the results of EIA and the protective test for vaccines of different groups was revealed (0.546), the highest correlation index being obtained for tissue-culture vaccines: 0.753. On the basis of the data obtained in this study the expediency of using EIA for the determination of the specific activity of rabies vaccines has been substantiated.

[The efficacy of a cultured rabies vaccine studied on guinea pigs previously infected with the rabies street virus]. / Izuchenie éffektivnosti kul'tural'noi antirabicheskoi vaktsiny na morskikh svinkakh, predvaritel'no zarazhennykh ulichnym virusom beshenstva.

In this work materials on the development of an experimental model for the study of rabies vaccines are presented. The comparative study of different immunization schedules for vaccines with different protective potency has been carried out. Guinea pigs infected with street rabies virus, strain k, were used as an experimental model. As shown in this investigation the optimum method of infecting the animals with strain k was intramuscular injection causing 50% mortality among the animals, the incubation period lasting 10-24 days. Only those tissue-culture rabies vaccines which had activity equal to 1.0-1.3 I. U. and, when injected into the animals, ensured survival rate ranging from 57% to 76%, depending on the immunization schedule, were shown to possess protective potency. It should be pointed out that survival rate among the animals receiving the preparation according to the reduced schedules recommended by WHO was higher than among those immunized daily for 14 days. In all groups immune response was observed. Still in the animals receiving the preparation according to the reduced schedules a higher level of virus-neutralizing antibodies was registered. Thus, an experimental model capable of being used for the evaluation of the quality of existing and newly developed antirabies preparations was obtained. Besides, we believe it to be expedient to carry out the field trial of rabies vaccines with activity equal to 1.0-1.3 I. U., using the reduced immunization schedules.

[A new rabies vaccine in public health practice in the USSR]. / Novaia antirabicheskaia vaktsina v praktike zdravookhraneniia SSSR.

A new antirabies vaccine prepared on the basis of virus grown in the ovine brain, purified from 85-90% of brain-tissue ballast substances and inactivated with beta-propilactone has been developed at the Moscow Research Institute of Viral preparations (USSR Acad. Med. Sci.). The preparation produces no neuro-allergenic effect in tests on guinea pigs. When injected to humans, the vaccine shows much lower reactogenicity than Fermi vaccine. High antigenic and immunogenic activity of the new vaccine has made it possible to work out a less intensive immunization schedule in comparison with that used for immunization with Fermi vaccine and nonconcentrated tissue-culture vaccine, viz. doses of 3 ml for 12 days or doses of 3 ml for 20 days with two booster immunizations. The preparation has been introduced into medical practice.

[Comparative assessment of the neurovirulence of vaccinal strains of the rabies virus]. / Sravnitel'naia otsenka neirovirulentnosti vaktsinnykh shtammov virusa beshenstva.

Neurovirulence of three vaccine strains of rabies virus ("Moscow", "Vnukovo-32", and "MIVP-74") was studied in mice using pathomorphology data. After intracerebral inoculations changes in the CNS were similar. The presence and the degree of the involvement of the Ammon horn is the main indicator of the infectious activity of the strain. The disease and death of the animals after inoculation with an attenuated strain may be due to the damage of intermediate neurons of descending projection tracts of the brain stem and cerebellum. Differences between strains in neurovirulence were most clearly observed after peripheral inoculation, when the "MIVP-74" strain, unlike the other two, proved to be apathogenic. Neurovirulent properties should be evaluated by characteristics of the CNS pathomorphology after intracerebral and peripheral inoculations.

A study of candidate rabies vaccines for a national reference preparation for the evaluation of antigenic potency.

An unconcentrated and a concentrated lot of rabies vaccine prepared in Syrian hamster kidney cell culture from the Vnukovo-32 strain have been examined for their suitability as national reference preparations for rabies vaccine. The antigenic potencies of the preparations were assessed by the NIH test using both fixed and street strains of rabies virus and by the method of antibody induction. The candidate vaccines were calibrated in comparative assays with the WHO 3rd International Reference Preparation of Rabies Vaccine (IRP3). The correlation between the level of virus-neutralizing antibody and the resistance of mice to intracerebral challenge with a fixed rabies virus strain was studied. The candidate vaccines were also examined by the thermal degradation test. It was found that both vaccines had appropriate antigenic potency and thermostability to be used as a national reference preparation of rabies vaccine.

[Effect of the interferon inducer RFf2 on the course of an infection due to the rabies virus in mice]. / Vliianie induktora interferona RFf2 na techenie infektsii, vyzvannoi virusom beshenstva u myshei.

The data of the study on the influence of an interferon inducer, phage RFf2 RNA, on the course of infection with fixed rabies virus and on the formation of postvaccination immunity are presented. The inoculation of the inducer in a dose of 1 mg/kg was shown to produce interferon in the blood of white mice within 6 hours up to 320 units/ml which decreased by 24 hours to 20-40 units/ml. No protective effect, however, was observed upon intracerebral inoculation of white mice with fixed rabies virus, CVS strain. An increased dose of the inducer resulted in the development of a marked protective effect (50%) particularly after peripheral inoculation of the virus when the latter was administered simultaneously with the inducer. The use of the inducer in combination with various types of rabies vaccines (tissue culture inactivated, sheep brain inactivated, Fermi type vaccines) exerted no influence on the resistance of the animals to subsequent inoculation with the virus or on the formation of postvaccination immunity. At the same time, inoculation of the inducer alone, two weeks before challenge, protected 30% of the animals as compared with 100% mortality in the control group. Further studies on the influence of interferon on the course of the infectious process in rabies and formation of postvaccination immunity are required.

Standardization of methods used for testing the safety of tissue culture rabies vaccines.

Tissue culture rabies vaccines are essentially new preparations intended for prophylaxis and treatment of rabies. However, the methods used for their testing are mostly the same as those used for rabies vaccines prepared from brain tissue. Therefore, it is extremely important to develop and standardize methods for testing tissue culture rabies vaccines. The main criteria for the evaluation of Vnukovo-32 production strain have been formulated. The strain has been characterized in pathomorphological studies; the degree and nature of lesions produced in animal brain tissue by various doses of antigen and different routes of inoculation have been determined. In order to ensure the specific innocuity of rabies vaccines inactivated preparations are produced. However, with the current methods of inactivation (treatment with beta-propiolactone or phenol, ultraviolet irradiation and others) some viral particles may occasionally remain active. Besides, reparative processes may possibly occur in utraviolet-irradiated viruses. The penetration of even sublethal doses of live virus into the body is highly undesirable, since under certain conditions the long-term harbouring of the live viral particle may result in the development of various pathological conditions. In order to reveal minimum amounts of live virus in the preparation a method of additional passages in a susceptible cell system using the fluorescent antibody technique has been developed. By this method it has been possible to detect the presence of live virus in 10 out of 51 lots of vaccine under test.

[Experimental study of rabies virus (Vnukovo-32 strain) persistence in white mice]. / Eksperimental'nye dannye po persistentsii virusa beshenstva (shtamm Bnukovo-32) v organizme belykh myshei

The duration of detection of the specific antigen in the cells of the central nervous system (CNS) of mice extraneurally infected with 450, 560 and 4380 LD50 of rabies virus, the Vnukovo-32 strain was studied. The antigen in the CNS cells was detected by the fluorescent antibody technique from the 11th until the 52nd day postinoculation, at 16-34 days being found in 50 to 100% of the experimental animals. In parallel, virus-neutralizing antibody was determined in the blood serum of the infected mice, and their brains were examined for the presence of rabies virus by bioassays. In most cases, serological results correlated with the antigen detection in the brain tissue. At 18, 29 and 34 days rabies virus was isolated from clinically normal mice inoculated subcutaneously, which by all the tests used did not differ from the other experimental animals. The results of the experiments attest to the possibility of rabies virus, the Vnukovo-32 strain, persistence in mice.

[Morphological study of neurovirulence of the Vnukovo-32 strains of rabies virus]. / Morfologicheskoe izuchenie neirovirulentnosti shtamma Vnukovo-32 virusa beshenstva

The central nervous system of white mice inoculated with the production Vnukovo-32 strain of tissue culture rabies virus was studied histologically. Intracerebral inoculation resulted in parenchymatous-inflammatory lesions with predominantly severe involvement of the Ammon horn neurons. Subcutaneous inoculations also revealed a rather significant degree of neurovirulence of this strain, although there were definite differences in the pathomorphological pictures observed after inoculation by this and intracerebral route. In mouse experiments the Vnukovo-32 strain showed instability of the properties both with regard to the degree of neurovirulence and to the duration of the incubation period.