Genetic resistance towards Salmonella infections

Botteldoorn N., Werbrouck H., Rijpens N., Herman L., Dedain V., Depuydt J., De Smet S.. 2002. Genetic resistance towards Salmonella infections. In : Second international symposium on Candidate Genes for Animal Health (C.G.A.H), Montpellier, France, August 16-18th 2002 : abstracts. CIRAD, INRA. Montpellier : CIRAD, Résumé, 1 p. International Symposium on Candidate Genes for Animal Health. 2, Montpellier, France, 16 August 2002/18 August 2002.

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Additional Information : Session 3 : Genetic resistance / susceptibility to infectious diseases (bacteria / virus)

Abstract : The NRAMP (natural resistance-associated macrophage protein) family of divalent-metal transporters was first identified by studies in mice on the genetic basis of susceptibility to intracellular parasites. The NRAMP family is widespread and strongly conserved with homologues in other animals, insects, worms and plants. Whereas NRAMP 2 transports a broad range of divalent metals in a pH-dependent fashion and is ubiquitous in all cells, the Nramp 1 gene is expressed exclusively in the lysosomal compartment of macrophages and acts in the early. pre-immune phase of infection. NRAMP 1 would be responsible for the Mn2+ or Fe2+ transport from the extracellular environment to the cytoplasm of the macrophage, and after forming of the phagosome, for export of Mn2+ out of the phagosome. The Nramp 1 gene is identical to the known Bcg/Lsh/Ity locus, and mutations in the Nramp 1 gene markedly reduce the ability of macrophages to control infection by several pathogens, respectively Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium avium, Leshmania donovani and Salmonella Typhimurium. The Nramp 1 has been mapped in the pig to chromosome 15 (SSC15) and a PCR-RFLP was described for studying the gene as a potential candidate gene in controlling pig resistance to Salmonella infections (Sun et al., 1998, Animal Genetics 29, 138-140). In our study, two polymorphisms in intron 1 and 2 of the Nramp 1 gene could be determined after elaborate optimisation of the methods. For intron 1 new primers were designed and the amplicon of 622 bp was restricted with HinfI to give fragments of 76 bp, 100 bp, 144 bp, 220 bp and 280 bp and a polymorphism was detected. For intron 2 a new polymorphism was detected (a deletion) with fragments of 210 bp and 199 bp after amplification. The frequency of the predominant allele was 0.93 and 0.90 on a total of 180 and 205 pigs for the polymorphism in intron 1 and intron 2 respectively. Similar allele frequencies of 0.90 and 0.91 in intron 1 and intron 2 were found in a sample of 392 and 391 slaughter pigs. In the latter population, no association between the Nramp 1 genotypes and the colon Salmonella status or the ELISA status could be demonstrated. In bacteria an orthologue of the eucaryotic Nramp 1 gene is described, the mntH gene. In the phagosome the bacterial and the eucaryotic NRAMP would compete for the transport of bivalent cations. The competition between both transport systems would determine the intracellular survival of the pathogenic bacterium (Agranoff et al., 1999, J. Exp. Med. 190, 717-724). Differences in the activity of the mntH gene could be important for the pathogenicity of the strain and the capacity to survive in the host. In our study, the expression of the mntH gene was compared for different pig related Salmonella Typhimurium strains after induction with EDTA and H2O2. Real-time quantitative RT-PCR was used to study the expression of the mntH gene relative to two housekeeping genes: rpoD and 16S. (Texte intégral)

Mots-clés Agrovoc : Salmonella, Maladie infectieuse, Résistance aux maladies

Mots-clés complémentaires : Résistance immunitaire

Classification Agris : L10 - Animal genetics and breeding

Auteurs et affiliations

  • Botteldoorn N., Centre for Agricultural Resarch Ghent (BEL)
  • Werbrouck H., Centre for Agricultural Resarch Ghent (BEL)
  • Rijpens N., Centre for Agricultural Resarch Ghent (BEL)
  • Herman L., Centre for Agricultural Resarch Ghent (BEL)
  • Dedain V., Centre for Agricultural Resarch Ghent (BEL)
  • Depuydt J., Centre for Agricultural Resarch Ghent (BEL)
  • De Smet S., University of Gent (BEL)

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