Genetic approaches to the study of disease resistance: with special emphasis on the use of recombinant inbred mice

Behaviour of Salmonella dublin in mice and rats upon intraperitoneal infection

The fate of Salmonella dublin in mice and rats after intraperitoneal infection was studied in relation to the bacterial net growth rate in the peritoneal cavity, liver and spleen, and to the corresponding inflammatory cellular response in the peritoneal cavity. Rats showed a better host defence, expressed by a greater cellular inflammatory response followed by suppressed bacterial growth. In contrast, the cellular response of mice to the higher bacterial growth was relatively low. These results may explain some mechanisms of natural resistance to salmonellosis in different hosts.

Haplotype-specific interactions of non-H-2-linked genetic factors controlling the mouse C4 and Slp protein levels

The influence of non-H-2 linked genes on the plasma levels of the H-2 S-region encoded proteins C4, Slp, and factor B was tested in Recombinant Inbred (RI) strains. The A X B and B X A RI strains exhibit a continuous range of C4 and Slp levels from very high to very low which reach beyond the levels of their parental strains, C57BL/6J and A/J, indicating involvement of several trans-regulatory (non-H-2-linked) genes. Only limited variation in levels of factor B has been found. No linkage relationship could be established for the trans-regulatory genes, because more than one gene is involved. A complex interaction of H-2 haplotype, genetic background, sex, and possibly maternal effect in determining the C4 and Slp protein plasma levels has been observed. The H-2-dependent sex effect is evident, because males have higher C4 levels than females in RI strains with H-2b but not with H-2a haplotype. This sex effect is also background dependent, because it is present in the H-2b congenic strain on A background (A.BY) but not in C57BL/10 and C57BL/6 (both H-2b). Mice from RI strains with H-2b haplotype have in general higher C4 levels than mice with H-2a haplotype.