Experimental evidence for major histocompatibility complex-allele-specific resistance to a bacterial infection

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Experimental evidence for major histocompatibility complex-allele-specific resistance to a bacterial infection. / Lohm, Jakob; Grahn, Mats; Langefors, Åsa; Andersen, O; Storset, A; von Schantz, Torbjörn.

In: Royal Society of London. Proceedings B. Biological Sciences, Vol. 269, No. 1504, 2002, p. 2029-2033.

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T1 - Experimental evidence for major histocompatibility complex-allele-specific resistance to a bacterial infection

AU - Lohm, Jakob

AU - Grahn, Mats

AU - Langefors, Åsa

AU - Andersen, O

AU - Storset, A

AU - von Schantz, Torbjörn

PY - 2002

Y1 - 2002

N2 - The extreme polymorphism found at some major histocompatibility complex (MHC) loci is believed to be maintained by balancing selection caused by infectious pathogens. Experimental support for this is inconclusive. We have studied the interaction between certain MHC alleles and the bacterium Aeromonas salmonicida, which causes the severe disease furunculosis, in Atlantic salmon (Salmo salar L.). We designed full-sibling broods consisting of combinations of homozygote and heterozygote genotypes with respect to resistance or susceptibility alleles. The juveniles were experimentally infected with A. salmonicida and their individual survival was monitored. By comparing full siblings carrying different MHC genotypes the effects on survival due to other segregating genes were minimized. We show that a pathogen has the potential to cause very intense selection pressure on particular MHC alleles; the relative fitness difference between individuals carrying different MHC alleles was as high as 0.5. A co-dominant pattern of disease resistance/susceptibility was found, indicative of qualitative difference in the immune response between individuals carrying the high- and low-resistance alleles. Rather unexpectedly, survival was not higher among heterozygous individuals as compared with homozygous ones.

AB - The extreme polymorphism found at some major histocompatibility complex (MHC) loci is believed to be maintained by balancing selection caused by infectious pathogens. Experimental support for this is inconclusive. We have studied the interaction between certain MHC alleles and the bacterium Aeromonas salmonicida, which causes the severe disease furunculosis, in Atlantic salmon (Salmo salar L.). We designed full-sibling broods consisting of combinations of homozygote and heterozygote genotypes with respect to resistance or susceptibility alleles. The juveniles were experimentally infected with A. salmonicida and their individual survival was monitored. By comparing full siblings carrying different MHC genotypes the effects on survival due to other segregating genes were minimized. We show that a pathogen has the potential to cause very intense selection pressure on particular MHC alleles; the relative fitness difference between individuals carrying different MHC alleles was as high as 0.5. A co-dominant pattern of disease resistance/susceptibility was found, indicative of qualitative difference in the immune response between individuals carrying the high- and low-resistance alleles. Rather unexpectedly, survival was not higher among heterozygous individuals as compared with homozygous ones.

U2 - 10.1098/rspb.2002.2114

DO - 10.1098/rspb.2002.2114

M3 - Article

VL - 269

SP - 2029

EP - 2033

JO - Royal Society of London. Proceedings B. Biological Sciences

JF - Royal Society of London. Proceedings B. Biological Sciences

SN - 1471-2954

IS - 1504

ER -