RESUMO
A genetic predisposition to resistance (R)/susceptibility (S) has been demonstrated for cowdriosis in certain goal lines. In order to identify genetic markers of R/S and to follow their transmission to the offspring, 4 groups of sires and dams were crossbred in 1991, 1992, and 1993: Rr, RS, SR, and SS. The offspring were challenged at the age of six months with subsequent challenge of the S parent. From 28 presumed S dams, 7 turned out R and from 2 presumed S sires, 1 was R and the other undefinable. The resistance rate was 76% for 21 RR kids and 45% for 20 RS kids. The R character seems to be better transmitted by dams than the S one. No difference was observed between R and S goats in terms of incubation period and body temperature level after challenge. There was no statistical effect found of sex, litter size, or birth mass on the R/S character; only a slight effect on daily mass gain was observed. Sperm has been collected from 4 S sires (died after challenge) and 5 R sires, and stored in liquid nitrogen in order to conceive additional SR and SS progeny. Several caprine leucocyte antigens seem to be genetic markers of R (Be 1, CLY) and of S (Be 9, Be 22, Be 23). Further powerful tools like microsatellites and probes defining other interesting loci possibly involved in disease pathogenesis are now at hand and will be included in future experiments.
Assuntos
Ehrlichia ruminantium , Doenças das Cabras , Cabras/genética , Infecções por Rickettsiaceae/veterinária , Animais , Cruzamentos Genéticos , Feminino , Marcadores Genéticos , Predisposição Genética para Doença , Cabras/imunologia , Imunidade Inata/genética , Larva , Masculino , Polimorfismo Genético , Probabilidade , Recombinação Genética , Infecções por Rickettsiaceae/diagnóstico , Infecções por Rickettsiaceae/imunologia , Espermatozoides/microbiologia , CarrapatosRESUMO
One hundred and twenty-seven Brahman cattle from several locations in Martinique (FWI), reared under different environmental conditions, were followed over three years and checked for clinical signs of dermatophilosis. To confirm that these animals had been in contact with the pathogen Dermatophilus congolensis, their sera were tested by ELISA. On the basis of this epidemiological study, 12 animals were classified as resistant (seropositive without clinical signs), belonging to herds in which the prevalence of the disease ranged from 25 to nearly 98%. Eighteen animals classified as highly susceptible displayed severe characteristic skin lesions. These 30 selected animals were typed for class I antigens of the major histocompatibility complex (MHC). MHC class II genes were analyzed using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques, on the exon 2 of the bovine leucocyte antigen (BoLA) DRB3 gene. Several alleles were found, according to patterns provided by the restriction enzymes used: Fnu 4HI, Dpn II, Hae III, and Rsa I. A particular sequence "EIAY" at amino acid positions 66/67/74/78 located in the antigen recognition sites (ARS) was found in the 12 animals classified as resistant, and 10 of them displayed also class I BoLA-A8 specificity. On the other hand, only 3 out of the 18 susceptible animals showed simultaneously the BoLA-DRB3 "EIAY" sequence and BoLA-A8 specificity. Interestingly, a serine residue at position 30 of the ARS was found in 8 of the susceptible animals and was completely absent from all resistant animals. Furthermore, in a same animal, the serine at position 30 and the EIAY sequence were never found simultaneously on the same haplotype. These results show a strong correlation between the resistant character to dermatophilosis and the association of MHC haplotypes: the BoLA-A8 specificity and the BoLA-DRB3 "EIAY" sequence at ARS positions 66/67/74/78 with the lack of serine in position 30. To confirm these results, family segregation studies are in progress and some interesting observations have been obtained.
Assuntos
Infecções por Actinomycetales/veterinária , Doenças dos Bovinos , Bovinos/imunologia , Genes MHC Classe I , Antígenos HLA-DR/genética , Dermatopatias Bacterianas/veterinária , Infecções por Actinomycetales/epidemiologia , Infecções por Actinomycetales/imunologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Bovinos/genética , Primers do DNA , Suscetibilidade a Doenças , Ensaio de Imunoadsorção Enzimática , Éxons , Feminino , Marcadores Genéticos , Cadeias HLA-DRB3 , Imunidade Inata , Leucócitos/imunologia , Masculino , Martinica/epidemiologia , Dados de Sequência Molecular , Linhagem , Reação em Cadeia da Polimerase , Mapeamento por Restrição , Dermatopatias Bacterianas/epidemiologia , Dermatopatias Bacterianas/imunologiaRESUMO
In two experiments, four and five goats were vaccinated by giving two subcutaneous injections of a preparation of inactivated elementary bodies of Cowdria ruminantium (Gardel stock) mixed with Freund's adjuvant. All vaccinated animals together with four naive controls were challenged intravenously with 5 ml of supernatant of a culture of bovine endothelial cells infected with the same stock of Cowdria. All goats developed a high temperature. Two out of four, and four out of five vaccinated goats survived the challenge whereas all naive control animals died within 7-12 days. Vaccinated goats which died survived longer than the controls. No difference in antibody titres was observed between protected and non-protected vaccinated goats. Moreover, immune sera from surviving goats, whether heat inactivated or not, were unable to neutralize the infection of bovine endothelial cells by Cowdria in vitro. Mechanisms conferring protection on the immunized goats are unknown at the moment but the hypothesis that T-helper lymphocyte populations have been elicited seems to be likely. This method of immunization with dead organisms will help in the search for protective antigens against cowdriosis.
Assuntos
Vacinas Bacterianas/administração & dosagem , Ehrlichia ruminantium/imunologia , Cabras , Hidropericárdio/prevenção & controle , Vacinação/veterinária , Vacinas de Produtos Inativados/administração & dosagem , Animais , Anticorpos Antibacterianos/imunologia , Antígenos de Bactérias/imunologia , Endotélio Vascular/microbiologia , Febre/veterinária , Adjuvante de FreundRESUMO
By using biological data and historical research, we have tried to explain the difference between resistance and susceptibility to the diseases transmitted (cowdriosis) or associated (dermatophilosis) with the tick Amblyomma variegatum, in two cattle breeds of the French West Indies: the Creole crossbred cattle of Guadeloupe and the Brahman zebu cattle of Martinique. Have been studied the polymorphisms of 5 independent genetic systems (erythrocytic haemoglobin, serum albumin and transferrin, the class I region of the BoLA complex and the gamma S crystallin gene) in different breeds comprising Bos taurus cattle of Europe and Africa, Bos indicus of West and East Africa, as well as the Brahman of Martinique and the Creole crossbred of Guadeloupe. By comparing the different allele frequencies of these 5 non related polymorphic loci and by using the two different mathematical matrices of NEI and of CAVALLI-SFORZA, have been established the genetic distances between these breeds. It appears clearly that the Creole cattle of Guadeloupe are in an intermediate position between the Bos taurus N'Dama breed of West Africa and two Bos indicus zebu breeds, namely the West African Sudan zebu and the Brahman. Thanks to studies of different archieves in the Caribbean and in Europe, historical evidence have been accumulated on the geographical origins and on the chronology of the establishment of Creole and Brahman cattle in the French West Indies. The high resistance of the Creole cattle of Guadeloupe to diseases associated with or transmitted by the "Senegalese" tick Amblyomma variegatum seems to be due to the inheritance of a pool of genes from West African cattle and more particularly from the N'Dama breed.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Doenças dos Bovinos/genética , Bovinos/genética , Infestações por Carrapato/veterinária , Animais , Cruzamento , Doenças dos Bovinos/história , História do Século XVI , História do Século XVII , História do Século XVIII , História do Século XIX , História do Século XX , Polimorfismo Genético , Índias OcidentaisRESUMO
Dermatophilosis is a disease associated with the tick Amblyomma variegatum, and a genetic predisposition to the manifestation of symptoms has been demonstrated. Indeed, the Creole cattle of Guadeloupe constitute a population which is highly resistant to this disease, whereas the Brahman zebu cattle of Martinique seem very susceptible. However, in this Brahman population there is a gradient regarding the severity of symptoms depending on individuals. In several herds of these pure zebu Brahman, kept under the same farming conditions, we selected susceptible and resistant groups because of the simultaneous presence of animals affected or not by clinical dermatophilosis. In these animals we studied several highly polymorphic genetic systems such as haemoglobin, albumin, the BoLA Complex (class I and II) and the gamma S crystallin gene. Only exon 2 of the BoLA-DRB3 gene, investigated by PCR-RFLP technique, showed interesting polymorphisms. We have established a genotypic map showing at least 4 different alleles of which 1 seems particular to one animal susceptible to dermatophilosis. Before reaching any conclusion further investigations with more DNA samples of susceptible animals are needed.