Mineralization and Preservation of an extremotolerant Bacterium Isolated from an Early Mars Analog Environment.

The artificial mineralization of a polyresistant bacterial strain isolated from an acidic, oligotrophic lake was carried out to better understand microbial (i) early mineralization and (ii) potential for further fossilisation. Mineralization was conducted in mineral matrixes commonly found on Mars and Early-Earth, silica and gypsum, for 6 months. Samples were analyzed using microbiological (survival rates), morphological (electron microscopy), biochemical (GC-MS, Microarray immunoassay, Rock-Eval) and spectroscopic (EDX, FTIR, RAMAN spectroscopy) methods. We also investigated the impact of physiological status on mineralization and long-term fossilisation by exposing cells or not to Mars-related stresses (desiccation and radiation). Bacterial populations remained viable after 6 months although the kinetics of mineralization and cell-mineral interactions depended on the nature of minerals. Detection of biosignatures strongly depended on analytical methods, successful with FTIR and EDX but not with RAMAN and immunoassays. Neither influence of stress exposure, nor qualitative and quantitative changes of detected molecules were observed as a function of mineralization time and matrix. Rock-Eval analysis suggests that potential for preservation on geological times may be possible only with moderate diagenetic and metamorphic conditions. The implications of our results for microfossil preservation in the geological record of Earth as well as on Mars are discussed.

Science-based management of livestock welfare in intensive systems: looking to the future.

As welfare is a multidimensional concept, its assessment should be a multidisciplinary process, providing a comprehensive assessment of animal welfare in any given system. The different measurable aspects of welfare may be turned into welfare indicators and assessed in a scientific manner. Assessment of welfare may combine different approaches that include the assessment of the production system and measurement of animal-based welfare indicators. With both approaches, however, risk managers face difficulties related to the availability of resources for implementing regulations and training staff. Most animal-based welfare indicators have the advantage that they can be measured whatever the production system; they relate to the animal's experience of its own state. It is essential to confirm the reliability of the measures and their robustness to ensure valid welfare assessment, especially for a science-based management approach. Many welfare indicators, even those measured at the individual level, are expressed at group level, as a proportion of the animals. This allows benchmarking and following of trends over time. The decision on what is or is not acceptable from a welfare point of view is an ethical or managerial one. The advantage of a graded welfare indicator is that it allows different thresholds to be set by different people, countries or organisations, depending on the purpose of the assessment. The development of a set of harmonised international welfare indicators for global trade is also discussed.

[New vaccines and new veterinary therapies derived from biotechnologies: examples of applications]. / Nouveaux vaccins et nouvelles perspectives thérapeutiques d'intérêt vétérinaire issus des biotechnologies: exemples d'applications.

The last ten years have seen the development of vaccines derived from deoxyribonucleic acid (DNA) recombination, which, when used in association with appropriate diagnostic kits, make it possible to distinguish vaccinated from infected animals. This article describes the general principles behind these vaccines, provides examples of different applications, e.g. vaccines against Aujeszky's disease, classical swine fever, rabies, avian diseases and rinderpest, and discusses the role of this type of vaccine in certain control plans. Deoxyribonucleic acid vaccines constitute a revolution in the concept of vaccination, which was previously based on the injection of a protein or a medium expressing a protein. It is now possible, however, to induce immunisation by direct injection of the gene that codes for the immunogenic antigen. Examples of such vaccines are described. Finally, the production of biological molecules used for therapeutic purposes thanks to genetic engineering techniques is illustrated by some examples concerning, in particular, animal bioreactors (transgenic animals).

Vaccines for minor use and minor species: technical difficulties to solve and consequences in legal definitions.

To identify the difficulties of the problem and to try to find some solutions with their consequences in legal provisions, different aspects have to be considered: the possible definitions of minor species and minor indications and the limits of such definitions, the present applicable directives and possible modifications induced by extrapolation of technical results, by reduction of requirements. According to the complexity of the problem, a pragmatic approach with a certain flexibility, founded on a case-by-case assessment, seems to be necessary. The basis of the CVMP position paper regarding the availability of products for minor uses and minor species mainly focused on medicinal products and MRLs is interesting to consider in the case of vaccines, in the light of technical requirements of Title II of EU Directive 2001/82/EC. Even if definitions of minor species and minor uses are needed to give a legal basis for the problem, they have limits and some examples will be given. Reduction of requirements and extrapolation seem possible in a relatively easy way when data are available for major use and major species. A reduction of requirements is much more difficult to set up when such data are not available. Requirements for quality, safety and efficiency will be assessed including the indications of notifiable diseases. When all these aspects have been considered, it is essential to avoid a disharmonised approach from the National Regulatory Authorities. So, the possibilities of a specific legal framework on << Minor Uses and Minor Species >> and a centralised procedure for marketing authorisations have to be discussed.

[Xenografts and the probability of viral zoonotic risk: reflections based on the sanitary control of a pig population free from specific pathogenic organisms and risk analysis]. / X¿enogreffes et probabilit¿e du risque viral zoonotique: r¿eflexions ¿a partir de la ma¿itrise sanitaire des porcs exempts d'organismes pathog¿enes sp¿ecifi¿es et analyse du risque.

An analysis of the risk factors involved has been made and a classical approach has been adopted, consisting of at least six stages. In the context of risk assessment and identification of potential danger, the pathogenic agents in the pig have been identified and those which are potentially pathogenic to man have been indicated. The risk of spreading, and exposure to certain pathogenic agents (SEPA) varies depending on the nature of the donor organs. The risk factors should be managed by a quality-control approach, which at the sanitary level should consist of controlling all production levels in the pig population, from rearing to slaughtering, and the subsequent removal of vital organs and tissue for xenotransplantation or xenografts. The personnel involved should also undergo rigorous medical examination.

[Risk and risk management connected with xenograft]. / Risques et gestion des risques li¿es aux x¿enogreffes.

Transmission of an animal virus to man is probably a constant reality. Pathogenicity is is not inevitable. Some vaccines were contaminated by cell culture but remain safe. Haemorrhagic fevers, despite limited outbreaks, are often cited in the media. On the other hand, the influenza A virus has been responsible for a large mortality. The cases of human infection with simian viruses (herpes virus B, cytomegalovirus, spumavirus, immunodeficiency virus) were accidental and have always remained asymptomatic. Monkeypox virus emerges in only some outbreaks. No transmission of animal endogenous retrovirus has been described. The precautionary principle, in the face of an unquantifiable risk, supposes that preventive measures should be taken in advance to reduce the risk at each step: isolation of the animal source after hysterotomy, transport in a germ-free environment, procurement and transplantation in rigorous surgical conditions, long-term follow-up surveillance of the patient, his or her family and healthcare workers. All the phases of the xenotransplantation procedure should be taken to limit the number of places and persons coming into contact with the recipient. Surveillance means regular clinical information. Various samples should be taken from the animal source, recipient, his or her family contacts, medical staff and cryogenically preserved as 'biological memory'. A National Xenotransplantation Register should be set up to gather and share all information on incidents.

Microbiological hazards of xenotransplantation. 1. Doubts and convictions relating to the risk of xenozoonosis.

The use of a xenogenic organ, tissue or cells for transplantation permits in theory the transmission of microbiological agents from one species to another. The risk of transmission of an unknown animal pathogen to man is assumed to be a public health issue. The genotype homology between human beings and non-human primates, theoretically, should increase the probability of transmission of microbiological agents. It is also assumed that pathogenicity is intensified in closely related species. Historically, most zoonoses come from species that are distant from man. Viruses are more often responsible for human disease than other animal microbial agents. Exposure of humans to animal viruses does not predicate infection. The pathogenicity of an animal virus for man may be immediate or delayed by a possible recombination of adaptive processes. The ultimate risk is the inter-human transmission of a highly pathogenic and fatal animal disease. The retrovirus possesses the enzyme which enables it to become inserted into chromosomal DNA. With an endogenous retrovirus, viral genomes are transmitted through heredity. Some of the retrovirally derived sequences in mammals are fossil viruses. It has been argued that the more closely the species are related, the less likely the retrovirus is to be transmitted, because of xenotropism.

Microbiological hazards of xenotransplantation. 2. Facing the risk.

The high number of xenotransplantations that have been carried out around the world since the beginning of the century, combined with the quantity of animal experiments that have exposed man to animal viruses under similar conditions, should be measured against the low incidence of known pathological consequences. The pathogenic potential of animal viruses for man, then, is unpredictable; and while the risk is acknowledged, it cannot be defined. Unless no benefit can be in xenotransplantation, the application of the precautionary principle to the extent of a moratorium seems to be excessive. The precautionary principle offers possible modes of action in the face of an unquantifiable risk. In the event of xenotransplantation, precautionary measures should be taken in advance, in order to limit risk to the maximum extent. The risk is reduced and the benefit/risk ratio becomes higher, rendering the challenge acceptable. Preventive measures should be taken as the knowledge grows about possible modes of transmission. Guidelines of good practice should be implemented at each step of the xenotransplantation process: birth of animal source by hysterotomy in a 'Specific Pathogen-Free' (SPF) centre rearing in incubator then in isolated conditions (SPF centre) transportation to and rearing in the procurement site (SPF hospital special wing) surgical procurement and xenotransplantation (hospital) post-surgical reanimation (intensive care unit) convalescence (isolated room--hospital) long-term recipient follow-up (home) All these steps should be taken in such a way as to limit the number of persons coming into contact with the recipient.

Technical requirements for the licensing of pseudorabies (Aujeszky's disease) vaccines in the European Union.

Under the light of current scientific knowledge, particularly with the progress of molecular biology and of the definition of assays to be performed, it is possible to know, as accurately as possible, the biological properties of a vaccine. Most requirements of EP monographs and Directive 92/18 are founded on that concept. It is clear that there is a balance between safety and efficacy in the case of a live attenuated viral strain that means the more efficient a strain, the less safe it can be. Nevertheless, the problem is more complex; considerable progress has been done to set up new finished products and particularly with the adjuvants which are used now even in combination with live attenuated AD strains. The efficacy of a vaccine can be greatly enhanced, maintaining good local and general safety. But a debate always occurs when it is necessary to determine the acceptability threshold of a vaccine with regard to its safety and efficacy. The points of view are often very divergent. But, in any case, this threshold depends on the local conditions in the different countries. It is clear that objectives of a vaccination program and the requirements about a vaccine cannot be the same in heavily infected countries with a compulsory vaccination program as in countries or regions with a low prevalence of AD infection or with an absence of any infection. Moreover, it must also be considered that vaccines constitute only one element of a control or eradication program targeted against Aujeszky's disease virus.

Eradication and control programmes against Aujeszky's disease (pseudorabies) in France.

In the present paper, an overview is given about Aujesky's disease (AD) eradication programmes currently applied in the different departments of France, together with the obtained results.

Influence of passive immunity on pig immunization with deleted Aujeszky's disease vaccines measured by the amount of wild virus excretion after challenge.

Four attenuated glycoprotein I deleted Aujeszky's disease virus (ADV) vaccines were compared on the basis of their ability to induce immunity in the presence of passive antibodies. The relative severity of clinical disease and amount of viral excretion following experimental challenge with virulent ADV were determined among groups of eight pigs that were unvaccinated or vaccinated with one of the four ADV vaccines. Vaccinated pigs received two vaccine doses, the first administered when passively acquired serum antibodies were still detectable at 10 weeks of age, and the second four weeks later. The experiment was divided into two trials, with vaccinated and unvaccinated control groups in each trial. Challenge with virulent ADV took place at 18 weeks of age for the first lot and 19 weeks of age for the second. Differences among the vaccines were observed with regard to clinical protection and viral excretion. Virulent virus was excreted by most of the vaccinated pigs from two to seven days after challenge. In the case of two of the vaccines, no virus excretion was detected in several of the pigs. It was confirmed that mean serum neutralizing titers at challenge are inversely associated with amount of viral excretion post-challenge. Difficulties in the standardization of vaccine trials with passive antibodies were discussed.

Hyaluronidase in human somatic tissues and urine: polymorphism and the activity in diseases.

The polymorphism of hyaluronidase (EC 3.2.1.35) (Hyase) was studied on a hyaluronan-polyacrylamide gel. Liver, placenta, ovary and breast tissue were found to have 7 active isoforms while leukocytes and platelets 5 and fibroblasts displayed no hyaluronidase activity. In serum, synovial fluid and urine soluble the most acidic forms are present. Desialylation showed that most of the hyaluronidase isoforms differ in the content of sialic acid. In patients with rheumatoid arthritis, hyaluronidase activity in the synovial fluid varied from not detectable to very high. A partial deficiency was demonstrated in sera from some patients with dysostosis multiplex without mucopolysacchariduria. In I-cell disease, hyaluronidase activity in serum was as that in controls.

Round table on control of Aujeszky's disease and vaccine development based on molecular biology.

A summary is given on the 4 topics which were discussed during the round table and which represent current knowledge on the molecular biology of Aujeszky's disease (pseudorabies) virus. They include a review on 1. the genome and gene products of the virus; 2. the viral genes associated with virulence; 3. the immunological role of the viral gene products and 4. studies intended to compare the efficacy of several commercially available vaccines and to establish a possible correlation between antibodies against individual structural viral proteins and degree of protection. It was concluded that gI deleted vaccines appear to be the best choice for use in intensive vaccination programmes towards eradication of Aujeszky's disease virus. However, there remains a need for development of more potent vaccines which induce strong humoral and cell mediated immune responses and afford complete protection, virological protection included. It is often observed that live vaccine strains which are completely avirulent lose much capacity to replicate and spread within the vaccinated animal. It is, however, not excluded that a certain degree of dissemination may be needed to be fully efficacious. Loss of virulence may thus be accompanied by too much loss of immunogenicity. An improved genetic stability of live vaccine strains when they are obtained by genetic manipulation, possibly justifies a more widespread dissemination of the vaccine strain in the body compared to that with conventionally developed strains or compared to what is presently allowed.