Social behaviour and susceptibility to infection in house mice (Mus musculus): effects of group size, aggressive behaviour and status-related hormonal responses prior to infection on resistance toBabesia microti

Abstract

SummaryAssociations between social rank, immunodepression and resistance toBabesia microtiinfection within single-sex groups of male house mice suggest rank-dependent suites of response involving different hormonal and immune changes in relation to aggressive behaviour and group size prior to infection. Reduced resistance among high-ranking males was associated with increased serum testosterone and corticosterone concentration and reduced serum immunoglobulin, but was independent of group size. Among low-ranking males, hormonal changes were not associated with resistance toB. microtibut changes in corticosterone concentration and measures of immunodepression increased with group size and aggressive behaviour. The results concur with earlier findings suggesting differences between high- and low-ranking mice in their physiological responses to social experience and consequently reduced resistance toB. microtiinfection among high-ranking individuals.