[Evolution of human anti-rabies vaccines from Pasteur to the present]. / L'évolution des vaccins antirabiques humains de Pasteur à nos jours.

Since the first immunization of man against rabies in 1885 by Louis Pasteur, antirabies vaccine has been continuously improved. Treatment failures, clinical infections by the fixed virus, neuroparalytic accidents in connection with myelin were progressively eliminated. Vaccines can be standardized and accurately controlled. After the original spinal cord, adult or newborn animals brains, embryonated eggs, primary tissue cultures, diploid and permanent cell lines have been used for the vaccine production. Today, safe and potent vaccines are available. New products might be developed from the technology of genetic recombinants.

Cell substrate and risk in killed poliomyelitis vaccine.

By using 3H-T labeled HeLa cell DNA it was possible to evaluate the quantity and the state of substrate DNA present in crude and purified killed poliovaccine. The results showed that 1.7 x 10(5) pg/ml of DNA is present in crude vaccine while in purified vaccine this product can not be detected (the limit of the detection method was 1.1 x 10(2) pg/ml). The theoretical problems of the risk of the formation of poliovirus pseudotypes and the potential contamination of the vaccine with a type C retrovirus are examined.

Quantitation of cell DNA in the evaluation of heteroploid cells as substrate for the preparation of killed viral vaccines.

To evaluate the risk of using heteroploid cell lines as substrates for viral vaccine production, the presence of cell DNA in poliovirus suspensions was examined. The time course of [3H]-thymidine-labeled HeLa cell DNA release during lytic infection with type 1 poliovirus was investigated. More DNA was found in filtered supernatants of poliovirus-inoculated cultures than in control cell supernatants. DNA concentration increased with time, paralleling virus release, but did not exceed 1.5% of the total DNA content of the culture. Only about 10% of this cell DNA was resistant to DNase treatment. By both ion-exchange chromatography and rate-zonal centrifugation it was possible to remove practically all cell DNA contaminating filtered poliovirus suspensions. Results obtained in this study permitted quantitative evaluation of cell substrate DNA present in poliovirus suspensions during successive steps of killed poliovirus vaccine preparation. Based on the sensitivity of our method, the amount of residual DNA was estimated at less than 0.02 pg per dose of purified vaccine.

Presence and quantification of cell substrate DNA in inactivated poliovirus vaccine.

In order to follow the fate of cell substrate DNA in inactivated poliovirus vaccine (IPV), experiments simulating different steps in IPV preparation were performed. For this purpose, 3H-thymidine-labeled HeLa cell DNA released during lytic infection with Mahoney type 1 poliovirus strain was used as tracer. Low speed centrifugation (1500 xg for 15 min.) of crude virus suspension removed on the average 98.5% of the total labeled cell substrate DNA. Repeated freezing and thawing of the crude virus suspension before centrifugation did not increase the residual 1.5% radioactivity found in the supernatant. This level of contamination was not significantly influenced by filtration of the supernatant through a 0.22 micrometer pore size membrane filter. DEAE-Sepharose CL-6B chromatography of poliovirus suspensions containing large amounts of 3H-thymidine labeled HeLa cell extracts completely removed the contaminating substrate DNA. These data showed that IPV free of cell substrate DNA can easily be obtained by a usual purification procedure.

Purification of poliovirus obtained from human diploid cells by means of DEAE-Sepharose.

Mahoney, MEF and Saukett poliovirus strains were grown on human diploid cells (MRC 5) and concentrated on Amicon filter. Concentrated viral suspensions containing 3H-uridine labelled virus were mixed with 14C-amino acid labelled cell extracts containing calf serum and passed through a DEAE-Sepharose column. Fractions eluted at various ionic strengths were analyzed for infectivity, radio-activity and serum content by counter immunoelectrophoresis in the presence of a rabbit anti-calf serum. A peak containing 40--60% of the input infectivity was easily obtained by elution with 0.01 M phosphate buffer at pH 7. The virus peak did not contain 14C or calf serum and its purity was controlled by PAGE-SDS electrophoresis and electron microscopy. This technique may be useful in the large-scale purification of viruses used in the preparation of inactivated vaccines.

[Detection of ovalbumin in influenza vaccine by electrosyneresis]. / Evaluation de l'ovalbumine par électrosynérèse dans le vaccin antigrippal.

Counterimmunoelectrophoresis was used for the detection of ovalbumin in influenza vaccine preparations throughout a purification process applied to allantoic fluids of embryonated eggs. With an antiserum able to detect ovalbumin to a concentration of 0.31 microgram/ml, the progressive elimination of this contaminant was followed until the final preparation of purified concentrated vaccine. This easy procedure appeared to be specific and highly sensitive.

Antibody response to anti-A/New Jersey/76 vaccines.

Experimental inactivated influenza vaccines prepared with strain X 53, derived from A/New Jersey/76 virus were injected to several groups of subjects. Different compositions of vaccine were used and the subjects were selected from different age groups. Antibody responses were measured 15 days after vaccination; it was then possible to evaluate the conversion rates, the percentages of subjects showing a protective level of antibodies and the average level of antibodies. The results show that a very small dose of antigen, probably acting as a booster, gives very good results in the older age group. On the other hand, young adults (below 23) react to a much lower degree to the vaccine. The results are discussed in relation to the age distribution of preexisting antibodies in the experimental groups and in the general population in France.

Effects of vaccination on an influenza epidemic in a geriatric hospital.

During winter 75/76 (from February 1 to March 31) we got the opportunity to follow the incidence of an influenza epidemic that occurred in the geriatric hospital of Ivry. Its population was, on the average, 83 years old. 958 persons were involved in this study: 523 out of them had been vaccinated with Pasteur bivalent Mutagrip A + B vaccine. The epidemic had a double origin: it was due to a virus A/Victoria and to a virus B/Hong Kong. A significant difference was noted between the vaccinated group and the nonvaccinated one. Serological (CF and HI) and virological investigations (virus isolation) were performed on 110 subjects. The clinical course followed by the disease was mild for the vaccinated and severe for the nonvaccinated. Mortality rate was 0.19% in the former against 3.90% in the latter. It has been thus possible to observe an "immunological fence" since it appears that when 79% of a given unit has been vaccinated, influenza incidence has been as much as three times reduced.

The use of jet-injectors in BCG vaccination.

In mass vaccination programmes, the jet-injection of vaccine may have considerable operational advantages over the classical techniques. The technical performance of two models of jet-injector, the Dermo-Jet and the Ped-O-Jet, in BCG vaccination was assessed in a number of studies which are reviewed by the authors. It is shown that the jet-injectors do not administer the full dose for which they are calibrated and that the size of the vaccination lesion varies more than after vaccination by syringe.By increasing the dosage considerably, the results of vaccination by jet-injection may be improved to a certain extent but the risk of unpleasant reactions is also increased.