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Biomedical subjects

J Chantal

Publications and source records attributed to J Chantal.

17 recordsLinked to original sources

Development of an ELISA for detection of myxoma virus-specific rabbit antibodies: test evaluation for diagnostic applications on vaccinated and wild rabbit sera.

An enzyme-linked immunosorbent assay (ELISA) was developed and compared with 2 reference diagnostic tests (indirect immunofluorescence [IF] and complement fixation) to detect myxoma virus-specific antibodies in sera from 50 rabbits experimentally vaccinated with an attenuated strain of myxoma virus or with a Shope fibroma virus. The ELISA was highly specific (100% specificity) and sensitive (100%, 21 days after homologous vaccination). In a comparison of the ELISA with the IF test in 128 wild rabbits from France, discrepant results were obtained in only 11 (8.6%) animals, which were positive with the ELISA and negative with the IF test. The higher sensitivity and the good specificity of the ELISA was confirmed in a serologic survey of 118 rabbits from 2 Kerguelen (Indian Ocean) islands, where the prevalence of myxomatosis varied considerably. The ELISA is an alternative serologic test for diagnosis, vaccine evaluation, and seroepidemiologic surveys of myxomatosis.

Animal Diseases↗

Impact of viral hemorrhagic disease on a wild population of European rabbits in France.

An outbreak of rabbit viral hemorrhagic disease (RVHD) and of myxomatosis occurred in a free-living population of rabbits (Oryctolagus cuniculus) near Paris (France) in 1995. Annual mortality rates were 88% in adults and 99% in juveniles. There was no difference in mortality rates between males and females. Since most adults were protected with myxoma antibodies after May, they probably died of RVHD. Mortality lasted throughout the year despite high proportions of rabbits having developed myxomatosis and RVHD antibodies, which suggests that the combination of the two diseases and the immunosuppressive characteristics of myxoma virus could be responsible for the mortality caused by RVHD. The proportion of juveniles with RVHD antibodies increased with their weight. Seroconversion against RVHD occurred in spring and autumn.

Animals↗

[Current status of anthrax or black fever].

Although anthrax is one of the oldest recognized infectious diseases in the world, it remains widespread particularly in tropical zones such as Africa. The impact of this major zoonoses is further enhanced by the fact that the pulmonary form can be used for biological warfare. Recently there has been a revival of interest in anthrax and research has benefited greatly from advances in molecular biology. The main factors accounting for the virulence of Bacillus anthracis have been elucidated. The author reports current data concerning pathogenesis, epidemiology and diagnosis and reviews progress made in the field of prophylaxis especially with regard to vaccines.

Africa↗

Protection of rabbits against rabbit viral haemorrhagic disease with a vaccinia-RHDV recombinant virus.

In order to protect domestic and wild rabbits against RVHD, we constructed a recombinant vaccinia-RHDV virus, using the Copenhagen strain of the vaccinia virus. This recombinant virus expressed the RHDV capsid protein (VP60). Analysis of the expressed product showed that the recombinant protein, which is 60 kDa in size, was antigenic as revealed by its reactions in immunoprecipitation and indirect immunofluorescence with the antibodies raised against RHDV. The recombinant virus induced high level of RHDV specific antibodies in rabbits following immunization. Inoculations by both the intradermal and oral routes allow protection of animals against a challenge with virulent RHDV.

Administration, Oral↗

[Serologic screening of certain zoonoses in the abattoir personnel in Djibouti].

A sero-prevalence survey was carried out on 108 workers of Djibouti slaughter-house in order to search out the carriers of agents of zoonotic diseases. The sera revealed prevalences of 6.5% for brucellosis, 0.9% for chlamydiosis and 42.6% for toxoplasmosis whereas no positive reactions were detected for Rift valley fever, Crimean Congo hemorrhagic fever, hydatidosis, and toxocarosis. These data are compared with results obtained from cattle and small ruminants slaughtered in Djibouti.

Abattoirs↗

[Myxomatosis in the sub-antarctic islands of Kerguelen, without vectors, thirty years after its introduction].

Myxoma virus was introduced into the Kerguelen archipelago in 1955-1956. Thirty years after its introduction, the virus is present in most areas inhabited by rabbits. Rabbit fleas and mosquitoes are absent from this group of islands and the disease is transmitted by contact. The timing of the beginning of new myxomatosis outbreaks, the absence of real epizootics as well as the higher percentage of infected males over females are specific observations in favour of this mode of transmission. The majority of 34 isolates tested between 1984 and 1988 are of intermediate virulence (Grades IIIA-IIIB). In these conditions, the impact of myxomatosis virus on rabbit populations estimated on two sites is low. Myxomatosis therefore plays only a minor role in the regulation of rabbit populations.

Animals↗

[Reaction of the complement fixation test on microtitration plates: application to the serology of myxomatosis. Comparative study of the results with the reaction of indirect immunofluorescence].

The authors describe a complement fixation technique on microtitration plates, using an antigen prepared from myxomas induced in rabbits. Compared with indirect immunofluorescence this technique was less cumbersome, more economical, easier to read and (as a conventional procedure) applicable in all laboratories. Results obtained with 165 serum samples tested by both methods showed good correlation and a specificity at least equal to that of indirect immunofluorescence. Taking into account its lower sensitivity, the positive threshold value for complement fixation under the described experimental conditions was a dilution of 1:4 (H50).

Animals↗

Detection of African swine fever virus by a biotinylated DNA probe: assay on cell cultures and field samples.

African swine fever virus was detected in various samples using a molecular hybridization technique. A fragment located in a constant area of the viral genome was biotin-labelled. This probe, when present at a concentration of 100 ng/ml of the hybridization solution, could detect 10 pg of target DNA immobilized on nitrocellulose with cellular DNA and RNA. The virus was evidenced after being passaged on monkey kidney cells, either 8 h post-inoculation (pi) if the multiplicity of infection (MOI) was at least 1 hemadsorbing unit (HAd) per cell, or 24 h later if the inoculum was diluted up to 10(-3) HAd per cell. When passaged on pig leukocytes with a MOI of 0.1 HAd per cell, the virus was evidenced 12 h pi, or 24 h pi with a MOI of 10(-2) HAd per cell. The probe did not hybridize with another DNA virus passaged on cells, neither did it react with non-infected blood or ham, but did so if African swine fever virus was resuspended with the samples. The spleen from uninfected pig and the lymph nodes from a pig which had died from hog cholera were found to be negative, whereas the spleen from a pig which had died of African swine fever was positive. These samples were also tested with a 32P-labelled probe whose sensitivity was 10-fold higher. A non-radioactive probe could be used both for the sensitive and specific diagnosis of African swine fever and the detection of the virus in an epidemiological survey.

African Swine Fever↗

[Serological response of the dog after primary antirabies vaccination using adjuvant or non-adjuvant vaccines].

The serological responses following a primary vaccination carried out one year before in two groups of dogs which received an inactivated cell culture vaccine containing or not an adjuvant (alumine-hydroxide) are compared. Neutralizing antibody titers assayed in mice, obtained with only one injection of the adjuvanted vaccine are at the same or a greater level than those induced by two injections of the non-adjuvanted vaccine administered two to four weeks apart (statutory schedule of rabies primary vaccination applied in France).

Adjuvants, Immunologic↗

Characteristics of Togo strains of Brucella abortus from cattle.

Thirty Togolese strains of Brucella from cattle were classified as members of B. abortus biotype 3 by the recommended methods of the Subcommittee on Taxonomy of this genus. However two unusual characteristics distinguish the Togolese strains from the main group of B. abortus: their mean oxidative profile altered on four of the conventional substrates (L-asparagine, L-arabinose, D-galactose and D-xylose) and their very slow growth on usual media. These two original characteristics are discussed from an epidemiological and taxonomical point of view.

Animals↗

[Clinical and epidemiological aspects of bovine brucellosis in tropical Africa].

Bovine brucellosis, in the tropical regions of Africa, is very different, both clinically and epidermiologically, from that observed in temperate zones. From the clinical point of view, abortion is rare and extra-genital lesions (hygromas and abscesses) are frequent. From the epidemiological point of view, the rate of infection is low and the disease has very little tendency to spread. The reason for these differences may be explained by climatic conditions (temperature, insolation, humidity) as well as by breeding conditions (principally nomadic or transhumant breeding). Where climatic and breeding conditions resemble those of intensive breeding in temperate zones the clinical and epidemiological aspects tend towards similarity with the usual form of bovine brucellosis.

Abortion, Veterinary↗