Mucin changes associated with abomasal parasitism in sheep : a thesis presented partial fulfillment of the requirements for the degree of Doctor of Philosophy at Massey University
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Date
2009
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Massey University
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Abstract
Mucins play important roles in host-pathogen interactions, influencing host
resistance, establishment of infection, as pathogen recognition sites and a source
of nutrients. They are highly glycosylated molecules and changes in
monosaccharide composition during parasitism have been reported. Effects of
parasites on monosaccharide component of fundic and duodenal mucins of sheep
were investigated in 3 age ranges (i) 4-4.5, (ii) 6 and (iii) 8-9 months old: (1) noninfected;
(2) infected with 10,000 Haemonchus contortus and euthanased 21 days
post infection (p.i.); (3) infected with 50,000 Teladorsagia circumcincta and
euthanased 28 days p.i. Three days-old lambs and 9 weeks-old lambs: (a) milk-fed,
(b) solid-fed and (c) solid-fed, infected with T. circumcincta were also included. The
effects of H. contortus and T. circumcincta infection in mucin changes were
significantly different in the fundus, however, both of them shared some similarities.
Infected sheep showed lower proportion of fucose and sialic acids in fundic and
duodenal mucins compared with non-infected animals, the level of sulphation
varied depending on the age of infected sheep: decrease in young sheep but
increase in older animals. H. contortus infection also caused increased proportions
of GlcNAc and Gal in fundic mucins and duodenal mucins respectively at all ages,
however, in T. circumcincta infection, it was shown that the alterations of mucins
were age-dependent. T. circumcincta infected sheep showed the significant
changes at young ages (4-6 months-old) while 8-9 months-old animals showed less
change in fundic mucins compared with non-infected animals. Effects of H.
contortus and T. circumcincta infection differed in the fundic mucins but were
similar in the duodenum. The study showed that parasitism caused the
modifications of monosaccharide composition in gastrointestinal mucins of sheep.
These alterations may result from parasite species differences, causing different
effects from the host’s immune response. The changes in mucin profiles observed
in the duodenum of sheep infected with abomasal nematodes suggested that the
host may respond to parasitism. This would facilitate the use of mucins from
accessible sources, without euthanasing the animals, to investigate the changes in
mucin compositions which can be used to diagnose the susceptibility or resistance
of sheep to parasites
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Keywords
Sheep, Parasites