International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


Nganga J 1, Nganga J 2, Iraqi F  1

1 International Livestock Research Institute (ILRI), Nairobi, Kenya, 2 Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya

Trypanotolerance quantitative trait loci (QTL) in mice have been mapped to chromosome 1, 5 and 17 and named Tir1, 2 and 3. Tir2 QTL has been fine mapped to less than 1cM using F13 advanced intercross lines. The particular Tir2 region spanning 2KB on the mouse genome was examined for possible candidate genes. Plausible candidate genes in the locus included toll like receptor 1 (TLR1) and TLR6 among others. Rapid defense mechanisms are provided through recognition of pathogen associated molecular patterns by TLRs. Their expression and cooperation is essential for the induction of interleukins through their interaction with membrane glycosylphosphatidylinositol (GPI) anchors. Spleen and liver tissues were collected at day 0, 4, 7, and 10 post infection from 4 groups of each of the resistant C57BL/6J and susceptible AJ mice. Tissue specific expression levels of each of the two genes was determined using a semi quantitative RT-PCR. Analysis of variance of the mean ratios of ß-actin as the house keeping gene with each of the two genes revealed that the genes are regulated in a statistically significant fashion. The level of TLR1 increased between day 4 and day 7 in the resistant C57BL/6J while it declined in the susceptible strain over the same time in the spleen tissue. In the liver tissue, the gene was only expressed after day 4 in both strains. While the level of TLR6 increased at the onset of the infection in both strains, they kept raising in the susceptible AJ strain while its level remained constant but at a lower level in the resistant C57BL/6J strain. By comparing TLR1 and 6 levels in the resistant and susceptible livestock, we can better understand their role in trypanotolerance hence develop new trypanosomosis control strategies in livestock.

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