Genotype and diet shape resistance and tolerance across distinct phases of bacterial infection

Background: Host defense against pathogenic infection is composed of resistance and tolerance. Resistance is the ability of the host to limit a pathogen burden, whereas tolerance is the ability to limit the deleterious effects of a given pathogen burden. This distinction recognizes that the fittest host does not necessarily have the most aggressive immune system, suggesting that host-pathogen co-evolution involves more than an escalating arms race between pathogen virulence factors and host antimicrobial activity. How a host balances resistance and tolerance and how this balance influences the evolution of host defense remains unanswered. In order to determine how genotype-by-diet interactions and evolutionary costs of each strategy may constrain the evolution of host defense, we measured survival, fecundity, and pathogen burden over five days in ten genotypes of Drosophila melanogaster reared on two diets and infected with the Gram-negative bacterial pathogen Providencia rettgeri. Resu...

背景：宿主抵御致病性感染的免疫防御可分为抗性（resistance）与耐受（tolerance）两类。抗性指宿主限制病原体载量的能力，而耐受则是宿主在既定病原体载量下减轻其有害影响的能力。这一区分表明，适应性最优的宿主未必拥有最为强悍的免疫系统，这提示宿主-病原体共进化的过程绝非仅局限于病原体毒力因子与宿主抗菌活性之间的升级式军备竞赛。宿主如何平衡抗性与耐受，以及这种平衡如何影响宿主防御的演化，这两个问题至今尚未得到解答。为探明基因型-饮食互作以及两种防御策略各自的演化成本如何制约宿主防御的演化，我们对以两种日粮饲养的10个黑腹果蝇（Drosophila melanogaster）基因型展开研究，在感染革兰氏阴性病原菌雷氏普罗威登斯菌（Providencia rettgeri）后，于5天内对其存活率、繁殖力及病原体载量进行了测定。Resu...