GENETIC PARAMETERS OF THE POLYGENIC REGULATION OF ANTIBODY RESPONSIVENESS TO FLAGELLAR AND SOMATIC ANTIGENS OF SALMONELLAE

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Abstract
Selective breedings of mice were carried out for quantitative antibody responsiveness to flagellar Ag., f (Selection III) or somatic Ag., s (Selection IV) of two non cross-reaction Salmonellae (Salm. tm., Salm. or.) alternated for immunization of consecutive generations. At the selection limit, these selections produced homozygous high (H) and low (L) responder lines for the character investigated: peak agglutinin response to optimal secondary immunization. The responsiveness to both f and s Ags. is submitted to polygenic regulation. The heritability (h2) realized during the selective breeding was 0.37 ± 0.07 for the response to f Ag. and 0.40 ± 0.1 for the response to s Ag. The respective part of genetic and environmental variance in F2 hybrids was 64% and 36% in selection III and 61% and 39% in selection IV. In the two selections, the dominance variance is negligible (2 hybrid variance is somewhat lower, the reason for this difference is discussed. The quantitative antibody response to f Ag. in selection III is controlled by about seven independent loci. The antibody response to s Ag. in selection IV is controlled by about four independent loci. A possible association of relevant genes with the H-2 locus was investigated. In selection III, no significant participation of H-2 linked genes, in the regulation of responses to f and s Ags. of Salm, tm and Salm. or. could be demonstrated. In selection IV a partial contribution of H-2 linked genes was observed concerning responsiveness to both f and s Ags. of Salm. tm.. but not to Salm. or. Ags. The H-2 effect accounts for 25% of the total interline difference.