A rabies vaccine from hamster kidney tissue cultures: preparation and evaluation in animals

From brain passage to cell adaptation: the road of human rabies vaccine development

A major challenge for global rabies prevention and control is the lack of sufficient and affordable high quality vaccines. Such candidates should be pure, potent, safe, effective and economical to produce, with broad cross-reactivity against viral variants of public health and veterinary importance. The history of licensed human vaccines reviewed herein demonstrates clearly how the field has evolved to the current state of more passive development and postexposure management. Modern cell culture techniques provide adequate viral substrates for production of representative verified virus seeds. In contrast to outdated nervous tissue-based rabies vaccines, once a suitable substrate is identified, production of high titer virus results in a major qualitative and quantitative difference. Given the current scenario of only inactivated vaccines for humans, highly cell-adapted and stable, attenuated rabies viruses are ideal candidates for consideration to meet the need for seed viruses in the future.

Rabies vaccines: from the past to the 21st century

Since the first development of a rabies vaccine by Pasteur in the late 19th century, second- and third-generation vaccines with improved efficacy and less reactogenicity have been developed for use in humans and animals. Despite the availability of safe but rather expensive vaccines based on inactivated virus propagated in diploid cell cultures, much of the human vaccinations worldwide are still carried out with nerve tissue-containing vaccines, which have various side effects. A number of experimental vaccines are under development that may provide alternative safe and potent but less expensive vaccine options. These include DNA vaccines, recombinant viral vaccines, and recombinant protein vaccines. Further testing is needed to determine if and which one of these novel vaccines will make their way into mass production and application in the future.

Vaccines produced by conventional means to control major infectious diseases of man and animals

This chapter reviews the development of some of vaccines and their use in controlling such major diseases as diphtheria, rinderpest, Newcastle disease, smallpox, pertussis, yellow fever, rabies, etc. Park–Williams Number 8 (PW8) strain is used to make diphtherial toxoid for vaccines. As a source of toxin, it is rendered nontoxic by incubation with formalin under alkaline conditions. The product's retention of antigenicity, enabling it to induce antitoxin antibodies, makes it an excellent pediatric vaccine. Vaccine against Rinderpest Virus was developed by Koch in 1897 by administering bile from infected cattle. Animals that survived were permanently immune. Formalin- and chloroform-inactivated vaccines were developed using tissues from the infected animals. For the control of Newcastle disease, a number of attenuated live-virus vaccines have been developed which are widely used to control the disease. The Bl strain, the LaSota strain, and the F strain are used to immunize birds of all ages by different routes, including by addition to drinking water and by spraying. Protection against rabies correlates with SN antibody, which can be assessed by a number of tests. Pasteur's classical vaccine, developed from infected spinal cord tissue dried at room temperature for 3–14 days, was given in a series of 21–28 inoculations beginning with material dried the longest and progressing through material dried for only 3 days.

Ethylenimine-inactivated rabies vaccine of tissue culture origin

The replication of seven rabies virus strains (CVS, HEP, PV, ERA, WIRAB, CPZ and BOLIVAR) in BHK cells and the inactivation dynamics of these strains by beta-propiolactone, acetylethylenimine, and ethylenimine were studied to find the most immunogenic strain and the most economic and stable inactivating agent for the production of an inactivated tissue culture rabies vaccine for animal use. The seven strains reached the peak of virus production 3 to 5 days after inoculation of the cell culture; PV yielded the highest virus titer (10(9) plaque-forming units/ml). The infectivity of virus suspensions containing 10(7) to 10(8) plaque-forming units/0.1 ml was inactivated by beta-propiolactone in 0.5 h, acetylethylenimine in 3.0 h, and ethylenimine in 1.0 h. Most of the vaccine lots prepared with the different strains and inactivating agents passed a modified National Institutes of Health potency test. The vaccines prepared with the PV strain had consistently higher antigenic values (equal or better than four) than the other six strains. This difference was highly significant (F6,12=59.8), whereas there were no statistically significant differences among the antigenic values of the vaccine lots prepared with the three inactivating agents. Batches of lyophilized and liquid vaccine stored at 4 C maintained potency for over 1 year. Ten dogs vaccinated with a vaccine prepared with the PV strain and inactivated with ethylenimine developed a good antibody response and resisted challenge 60 days after vaccination, while seven of eight nonvaccinated controls died of rabies. This information indicates that an inactivated, stable, economic, and easy-to-prepare rabies vaccine can be produced in BHK cells by using the PV strain and ethylenimine as an inactivating agent.

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.