[Antigenic activity and the reactogenicity of a concentrated, purified, UV-inactivated cultured rabies vaccine]

The results of the study of concentrated, purified, UV-inactivated cell-culture rabies vaccine, obtained from strain Vnukovo-22, passage 33-40, in the primary culture of Syrian hamster kidney cells, demonstrated the pronounced antigenic potency of this vaccine: when introduced intramuscularly in 3-4 injections at certain intervals, it induced the production of virus-neutralizing antibodies in high titers. In tests on volunteers the vaccine proved to be nonreactogenic.

[Antirabies vaccine from human diploid cells initial vaccination experiences]

The Authors describe their experience with a new human rabies vaccine (HDCV), prepared on human diploid cell strains (HDCS). The reported experience is largely positive for almost total absence of significant fastidious side-effects.

[Production of rabies vaccine in animal diploid cells]

Modalities for production of inactivated rabies vaccine derived from diploid hamster cell cultures are reported. The inactivated concentrated virus, purified by zonal centrifugation, is utilised for the preparation of vaccines destinated to carnivores, either in the form of monovalent vaccine or associated with distemper and canine contagious hepatitis vaccines. The inactivated concentrated virus is utilised for the preparation of bovine vaccine. The procedure is compatible with industrial production. The results concerning safety and potency tests of the experimental lots are presented.

Purification, concentration and evaluation of rabies virus antigen

A number of concentration and purification procedures for rabies virus antigen have been developed during the last decades but only ultrafiltration and density gradient centrifugation have been found suitable for large scale production. The antibody binding test developed by Arko, Wiktor and Sikes was modified and was found useful for evaluation of inactivated antigen-concentrates. This test was used as an 'in process' control. Three examples of practical experience are reported and discussed.

[Modalities of production and immunity conferred by an inactivated rabies vaccine originating from cell culture]

Further to guidelines advised by the World Health Organization, an inactivated Rabies vaccine was prepared from virus propagated on cell culture. This vaccine is presented either in the freeze-dried form or in the liquid form together with an immunity adjuvant. The specific and nonspecific immunity of the vaccine is excellent. The potency, tested in laboratory animals and in species for which the vaccine is intended, satisfies recommendations published by the W.H.O. The immunity persistence, evaluated by the titration of serum antibodies and by challenge with a pathogenic virus, proves to be excellent 3 years following primovaccination. Finally, the stability of this vaccine is an interesting factor for its application, especially in the form of a combined vaccine.

Properties of rabies vaccine freed of neuroallergenic factor from brain tissue

Fixed rabies virus in the form of infected sheep brain suspension was freed from approx. 80% of ballast proteins, inactivated by beta-propiolactone and lyophilized. The vaccine thus obtained was devoid of neuroallergenicity when tested on guinea pigs and was highly antigenic and immunogenic. The vaccine caused no generalized reactions in volunteers; local reactions were weak and of short duration. Antibody formation was intensive in all volunteers.

[Immunization of calves with a rabies vaccine from suckling mouse brain]

This paper summarizes the results obtained in a study on the duration of immunity in calves immunized with suckling mouse brain (SMB) rabies vaccine, supplemented with aluminum hydroxide. Rabies circulating antibodies were detected ten days after vaccination in 100% of the 31 vaccinated calves. They began to decrease 90 days after immunization. Of the 15 calves challenged one year postimmunization, 5 (33%) had no detectable antibodies at serum dilution 1:5, but all were protected against the challenge dose virus which killed 75% (3/4) of the non vaccinated controls. The results obtained suggest that SMB rabies vaccine can be used successfully to immunize calves aged from 7 days to 6 months. Since 15 to 20% of the cattle population of a country is less than one-year-old, the protection of this population against rabies with an inactivated vaccine would decrease the number of susceptible animals and facilitate both the vaccination procedures and the movement of animals from rabies-free areas to those where the disease is enzootic.

Freeing rabies virus of the neuroallergenic factor from brain tissue

A method of fixed rabies virus purification from infected sheep brains was proposed. It consisted of suspending the brain tissue in phosphate-buffered hypertonic (0.3 M) NaCl solution, shaking at 37 degrees C and low speed centrifugation at the same temperature. From 65 to 85% ballast proteins were removed, the neuroallergenic activity of the material was lost, but practically no losses of the virus occurred.

[Concentrated adsorbed, cultured antirabies vaccine]

In animal experiments the antigenic activity of adsorbed concentrated tissue-culture rabies vaccine was shown to be significantly higher in comparison with the nonadsorbed concentrated preparation when introduced in 2 intramuscular injections at an interval of 21 and 30 days, as well as in comparison with commercial tissue-culture vaccine when introduced subcutaneously in a 14-day course of daily injections.

[A purified rabies vaccine from human diploid cell cultures (author's transl)]

In order to improve the tolerance of rabies vaccine from human diploid cell cultures, the rabies virus antigen is purified in the sucrose density gradient by means of a flow ultracentrifuge. The purified virus has a specific infectiosity of 10(9) LD50 and a speicific activity of 250 units "relative activity" per 1 mg protein. The purified vaccine has been shown to be well tolerated, effective and stable.

[Antigenic activity of a concentrated and purified cultured antirabies vaccine from the Vnukovo-32-107 strain]

Humoral response (virus-neutralizing antibody production) to immunization with inactivated 30-fold concentrated and purified tissue culture rabies vaccine was studied in monkeys and human volunteers. Two doses of the preparation spaced 20 days apart and given intramuscularly or intradermally to monkeys induced in them much more intensive antibody production (4--213-fold by titer) than 6 daily injections of unconcentrated vaccine. In 10 human volunteers immunized with 1.5 ml doses of the concentrated vaccine intramuscularly twice 20 days apart antibody titers 40 days after immunization varied from 1:79 to 1:6250 (average 1:1067). In another group of 10 human volunteers immunized intramuscularly with the concentrated vaccine 3 times at 0, 1st and 20th day, antibody titers 40 days after immunization were 1:112--1:3273 (average 1:508). These values are significantly higher than the average titers in humans vaccinated with unconcentrated tissue culture of brain vaccine of Fermi type. The concentrated vaccine proved to be a preparation of low reactogenicity: no systemic reactions were observed among vaccinated volunteers; 4 out of 20 volunteers had a mild, transient (1 day) local reaction (hyperemia of less than 1.5 cm in diameter).

[Zonal centrifuge purification of human rabies vaccine obtained on bovine foetal kidney cells (author's transl)]

A human rabies vaccine is prepared on bovine foetal kidney cells in absence of serum. This vaccine is concentrated and purified by zonal centrifugation. An immunogenic vaccine is obtained from the purified viral particles. Preliminary results are reported.

Zonal-centrifuged human diploid cell rabies vaccine

In order to reduce the risk of allergic reactions, a purified human diploid cell culture rabies vaccine was developed. Pitman-Moore strain of rabies was propagated in WI-38 or MRC-5 cells. Both cell strains were found to be equally suitable for pro agation of rabies virus. The virus was purified and concentrated by continuous-flow sucrose density gradient ultracentrifugation. Virus peak fractions were diluted with a stabilized and then inactivated with BPL and freeze-dried. According to the standard NIH test for potency, the vaccine proved to be very potent and stable. The results of initial clinical applications of the vaccine will be presented.

The vaccination of man and other animals against rabies

Rabies vaccines and their use in man and other animals are described. Safe and reliable vaccines are available for veterinary use, but many of the problems associated with the vaccination of humans remain unsolved.

Immune response in primates vaccinated with duck embryo cell culture rabies vaccine

Adult rhesus monkeys (Macaca mulata) were vaccinated with four inactivated rabies vaccines, including two cell culture vaccines, one zonal purified cell culture vaccine, and a 10% extracted duck embryo vaccine. The vaccines were potency tested by both National Institutes of Health (NIH) and Habel methods and passed one or both tests. However, a vaccine having acceptable potency by one method frequently failed or was marginal by the other procedure. Groups of three monkeys were inoculated with each vaccine by one of two schedules. The first consisted of four weekly 1-ml doses followed by a 1-ml booster dose at 6 months, and the second consisted of seven daily 1-ml doses of vaccine with no booster. Both zonal purified and extracted duck embryo vaccines induced detectable neutralizing antibody by day 7 with either schedule, and antibody titers elicited by the cell culture vaccine remained high through 210 days. However, antibody titers produced by the 10% duck embryo vaccine dropped sharply after their 28-day peak. Duck embryo cell culture vaccines with low or marginal potency as measured by Habel or NIH tests still produced rapid, high levels of serum-neutralizing antibody in primates. LD(50) or NIH and Habel tests as measured in mice were not necessarily good indices of antibody response in the primate host. The need for a cell culture potency test that will yield a more predictable correlation with the definitive host's antibody response is discussed.

Purified rabies vaccine (suckling rat brain origin)

A 10% suckling rat brain rabies vaccine free from encephalitogenic activity was prepared and inactivated with 1:8,000 beta-propiolactone (BPL), or ultraviolet light, or a combination of ultraviolet light and BPL, or 1% phenol. Potency was excellent in all samples, with the exception of the phenolized product which was marginal. A purified suckling rat brain (SRB) vaccine prepared by zonal centrifugation and inactivated with 1:8,000 BPL contained about 0.01 the amount of protein nitrogen of the unpurified 10% SRB vaccine. This purified product passed the National Institutes of Health potency test for rabies vaccine after administration of a quantity equivalent to a standard 10% brain suspension.