PubMed Health⌕ Search

Biomedical subjects

J P Soulebot

Publications and source records attributed to J P Soulebot.

At least 19 recordsLinked to original sources
PubMed1993

In vitro potency testing of inactivated biologics: current situation in the E.E.C.

A whole series of regulations are currently being implemented in the European Economic Community in the field of biologics that are complementing the European Pharmacopoeia and widening its field of application. The object of these new regulations is to ensure a very high level of safety and efficacy, but unfortunately, they tend towards the increased use of animals for testing purposes. However, for ethical, economic and practical reasons, the number of animals used must be reduced which makes the development of in vitro tests an important issue. In vitro testing is complicated since inactivated products are often adsorbed onto aluminum hydroxide or presented as an emulsion, and tests are easier to carry out prior to final blending operations. It is suggested that in-process controls can replace finished product controls when batch-to-batch consistency has been formerly validated, a quality assurance system has been adopted, and that system is regularly subjected to a suitable inspection procedure. The new inspection system applied in the United Kingdom should facilitate progress in this field and lead to a parametric release system. To avoid future problems, it is particularly important that efforts be made now for the harmonization of new techniques between Europe and the United States.

Animal Testing Alternatives↗
PubMed1984

[The vaccination of cattle against rabies. Antibody kinetics, resistance to challenge three years after vaccination].

The kinetics and the titre of the serum neutralising antibodies have been studied for 55 months, in eight cows already vaccinated against rabies with a commercial vaccine. The titres remained stable during this period and increased after the booster injection 16 months after the primary immunization. The protection obtained with this vaccine was tested. These cattle and five controls were inoculated in each masseter muscle in the 55th month with a street rabies virus suspension (5 x 10(5) MICLD50). None or very low serum neutralising antibody titres were found among the controls. However, the inoculation of street rabies virus elicited an irregular immune response among the vaccinated cows. All the controls died whereas all the cows which had received one booster injection survived.

Animals↗
PubMed1983

Passive protection of newborn calves against rotavirus by vaccination of their dams.

The rotavirus is considered as being one of the major causes of acute gastroenteritis; it occurs in cattle farms where, either by itself or in association with other pathogenic agents, it is responsible for a high percentage of neonatal morbidity and mortality. Over two consecutive years, field trials were done using inactivated rotavirus vaccine in oily excipient inoculated to pregnant cows. Results obtained prove a significant increase in the rate of colostral antibodies and a very real prolongation of the excretion of these antibodies into the milk up to and over 28 days post-calving. From the clinical point of view, outbreaks of diarrhoea in calves born of vaccinated cows were less common and less serious, but more importantly, the rotavirus was found to be playing a far less significant role. It was thus demonstrated that the presence of a great quantity of specific antibodies in the intestine plays a protective role. This mechanism was the origin of the concept of lactogenic immunity and is particularly well demonstrated by the study of viral excretion at the virulent challenge of calves having followed differing lactation programmes.

Animals↗
PubMed1983

Propagation of bovine coronavirus on Vero cell line: electron microscopic studies.

The in vitro adaptation of enteric coronaviruses is difficult. In our Laboratories, the multiplication of the COI bovine strain (F15 origin), on Vero cells is commonly practised. Since other laboratory tests (hemagglutination inhibition, cytopathic effect and immunofluorescence) are not totally reliable, electron microscopic studies present definite advantages in the interpretation of viral synthesis, as demonstrated at the 11th passage in our study. We were able to observe the following: --that the rate of infected and productive cells was important; --that the stages of viral morphogenesis were well established; --that the viral synthesis was prolific and regular and could be witnessed by important intracytoplasmic storage. The results of this study prove that the choice of our cell system is very satisfactory.

Animals↗
PubMed1982

[Particularities of the morphogenesis of the rabies virus and of its morphology observed during routine culture controls through the electron microscope].

Whilst practising routine controls with an electron microscope on NIL 2 cell cultures infected by the rabies virus, the occasion arose to reveal certain features of the morphogenesis of this virus and the particular action of glutaraldehyde which alters the aspect of the rabies virus. During the cultures, we witnessed, in succession, the production of morphologically normal virions, then progressively degraded virions whilst the cells recover and develop towards a chronic infection state. Glutaraldehyde treatment of the suspensions proved to be of great interest for electron microscopy observation.

Animals↗
PubMed1982

Thermostability of the rabies virion. Optical density measurement technique applications.

The thermal degradation of rabies virus was determined by the variation in optical density at 260 nm during temperature rise. This variation, linked to denaturation of RNA, was seen by an irreversible sigmoidal curve. Analysis of the state of the virion by ultracentrifugation did not show any alteration in sedimentation. Electron microscopy revealed a release of nucleic acid of the virions which were burst to a greater or lesser degree. The technical conditions of these measurements--speed of temperature rise and virus preparation--are defined. The form of the curve and the different measurements which develop from it, enable the influence of numerous factors linked either to the sodium, calcium and magnesium environment, or to an alteration of the virus by chemical substances, especially inactivation agents, to be observed. The study of the thermal degradation of rabies virus is an interesting method of determining the action of different factors on the stability of the virion.

Animals↗
PubMed1982

Rabies virus pathogenicity and challenge. Influence of the method of preparation, the route of inoculation, and the species. Comparison of the characteristics of the modified, fixed and wild strains.

The challenge we carried out, which regularly brought about the death of the control animals, led us to study the different factors influencing the pathogenicity of the rabies virus. So, the method of preparation is important. The strain NYC, prepared from the salivary glands is extremely pathogenic for dogs; however, when it is prepared from mouse brains after nine passages have been made, it proves to be already partially modified. One then notices a death-rate which is less severe, even when larger quantities of virus are employed, and also the presence of some aberrant phenomena. (The survival of some of the infected animals and the nature of their inapparent forms of infection were confirmed by serology.) The significance of the route of inoculation in the different species of animals was studied. The injection in the crotaphytes was reserved for dogs, the cervical muscles for cats and the masseters for sheep. Paradoxically, cats prove to be most resistant to the challenge under our conditions. Finally the numerical data, allowing us to compare the different strains, modified, fixed or wild, was established. The data was based on the incubation period and on the differences between the titres obtained via intramuscular routes and intracerebral routes in the mice.

Animals↗
PubMed1982

[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.

Animals↗
PubMed1982

Infectious bovine rhinotracheitis: study on the experimentally induced disease and its prevention using an inactivated, adjuvanted vaccine.

Experimentally induced IBR was studied in calves. Intranasal challenge enabled reproducible results to be obtained, both from qualitative (clinical aspect) and quantitative points of view (virus excretion, temperature); local and general immunity were also evaluated. This challenge method is useful when studying IBR vaccines. The disease was also experimentally induced by putting healthy animals into contact with diffusor calves. A single injection of inactivated vaccine in oily adjuvant already conferred good protection; it was 100% successful against the experimentally induced disease when administered two times at a 7 or 14 day interval. Immunity obtained was long-lasting and even persisted up to one year. Therefore, this vaccine is advised for vaccination in both contaminated and high risk areas. Results obtained for both safety and potency suggest that this killed vaccine should be used rather than live vaccines.

Adjuvants, Immunologic↗
PubMed1981

Experimental rabies in cats: immune response and persistence of immunity.

Experimental rabies was studied in cats under defined conditions. A correlation between the virus dosage and the incubation period was established and results were compared with those published previously by others. the susceptibility of cats to rabies virus appears to be paradoxical. The persistence of the immunity induced by an inactivated rabies vaccine prepared form cell culture-propagated virus used in combination with feline panleukopenia vaccine, with or without adjuvant, was studied through severe virulent virus challenge. Complete protection was observed after more than 3 years following a single vaccination. A proposed vaccination schedule is discussed.

Animals↗
PubMed1980

Intradermal immunization with rabies vaccine. Inactivated Wistar strain cultivated in human diploid cells.

We report a comparative study of the Mérieux Institute's inactivated rabies vaccine administered intradermally or subcutaneously. Vaccine safety was satisfactory, with only minor local and generalized reactions. Serological effectiveness was outstanding: all of those who had been seronegative became seropositive following either two intradermal or subcutaneous injections given one month apart. A comparison of the intradermal and subcutaneous routes demonstrated several important points. Antibody titers developing after subcutaneous immunization were greater than after intradermal immunization. The kinetics of antibody development during primary immunization were parallel in the two immunization protocols. Eleven months after primary immunization, subcutaneous administration of a booster dose of vaccine resulted in a titer elevation 1.86-fold greater than that in intradermal administration. Each of these levels indicated good serological response.

Adult↗