TY - JOUR
T1 - Genetic variation in resistance to mixed, predominantly Teladorsagia circumcincta nematode infections of sheep
T2 - From heritabilities to gene identification
AU - Stear, M. J.
AU - Boag, B.
AU - Cattadori, I.
AU - Murphy, L.
PY - 2009/5
Y1 - 2009/5
N2 - In cool temperate areas, such as Scotland, sheep are infected by a variety of nematodes but the dominant nematode is Teladorsagia circumcincta. Resistant animals have one or more of the following features: fewer adult nematodes, more inhibited larvae, shorter adult nematodes and decreased production of nematode eggs. In lambs at the end of the first grazing season, the heritability of adult worm length is very strong, whereas the heritability of egg production is moderate. The heritability of worm number is low while there is no detectable genetic variation in the number of inhibited larvae. The major mechanisms underlying resistance to T. circumcincta appear to be the IgA mediated suppression of worm growth and the mast cell mediated regulation of worm number. Mast cell responses are slow to develop, possibly because they are responsible for protein loss and reduced growth of the host. Two genes have been repeatedly associated with resistance to T. Circumcincta: the MHC class II DRB1 locus on chromosome 20 and the interferon-γ locus on chromosome 3. Although the causative mutations are still unknown both genes are plausible candidates.
AB - In cool temperate areas, such as Scotland, sheep are infected by a variety of nematodes but the dominant nematode is Teladorsagia circumcincta. Resistant animals have one or more of the following features: fewer adult nematodes, more inhibited larvae, shorter adult nematodes and decreased production of nematode eggs. In lambs at the end of the first grazing season, the heritability of adult worm length is very strong, whereas the heritability of egg production is moderate. The heritability of worm number is low while there is no detectable genetic variation in the number of inhibited larvae. The major mechanisms underlying resistance to T. circumcincta appear to be the IgA mediated suppression of worm growth and the mast cell mediated regulation of worm number. Mast cell responses are slow to develop, possibly because they are responsible for protein loss and reduced growth of the host. Two genes have been repeatedly associated with resistance to T. Circumcincta: the MHC class II DRB1 locus on chromosome 20 and the interferon-γ locus on chromosome 3. Although the causative mutations are still unknown both genes are plausible candidates.
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U2 - 10.1111/j.1365-3024.2009.01105.x
DO - 10.1111/j.1365-3024.2009.01105.x
M3 - Review article
C2 - 19388948
AN - SCOPUS:64549115966
SN - 0141-9838
VL - 31
SP - 274
EP - 282
JO - Parasite Immunology
JF - Parasite Immunology
IS - 5
ER -