Experiment
Trypanosome resistance QTLs Tir1 (chr17), Tir2 (chr5), and Tir3 (chr1) were further characterized by the study of congenic mouse lines. Donor DNA from Trypanosome resistant strain C57BL/6OlaHsd was transferred onto the genetic background of Trypanosome susceptible strain A/JOlaHsd for each of the 3 QTL. Donor strain C57BL/6OlaHsd exhibits a mean survival time of 68.8 days when challenged with Trypanosome congolense while background strain A/JOlaHsd exhibit a mean survival time of 29.7 days. All congenic lines exhibit increased resistance to challenge with T. congolense relative to the A/JOlaHsd background strain. Following T.congolense challenge the Tir1 congenic had a mean survival time of 57.9 days while the Tir2 and Tir3 congenics had mean survival times of 49.5 days and 46.8 days, respectively.
It was observed that when each of the congenic lines was backcrossed to resistant donor C57BL/6OlaHsd the resulting progeny exhibited mean survival times surpassing that of the resistant donor. The mean survival times of the congenic backcross animals ranged from 120.4 to 128 days.
06.04.2015 Curators Note: Because Tir1, Tir2 and Tir3 were originally mapped in 1996 In J:98907 using (BALB/cOlaHsd x C57BL/6JOlaHsd)F2 animals which differ from the congenic mice used here we consider this a separate map study and have assigned unique QTL nomenclature to the QTL identified here.
On Chromosome 17 the following markers were used in marker-assisted introgression of the Tir4 congenic line: D17Mit29 (15.1 cM), D17Mit16 (17.4 cM), D17Mit11 (22.8 cM).
On Chromosme 5 the following markers were used in marker-assisted introgression of the Tir5 congenic line: D5Mit200 (36 cM), D5Mit113 (42 cM), D5Mit10 (54 cM).
On Chromosome 1 the following markers were used in marker-assisted introgression of the Tir6 congenic line: D1Mit60 (58.7 cM), D1Mit87 (62.1 cM), D1Mit217 (64.1 cM).
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