Data from: Maternal immunization increases nestling energy expenditure, immune function, and fledging success in a passerine bird

Female birds transfer maternally-derived antibodies (matAb) to their nestlings, via the egg yolk. These antibodies are thought to provide passive protection, and allow nestlings to avoid the costs associated with mounting an innate immune response. To test whether there is an energetic benefit to nestlings of receiving matAb, we challenged adult female tree swallows (Tachycineta bicolor) prior to clutch initiation with either lipopolysaccharide (LPS) or saline (Control). Following hatching, one half of each females nestlings were immunized on day 8 post-hatch with LPS or saline, and for 4-hrs post immunization nestling metabolic rate (MR) was measured. There was no difference in either LPS-reactive antibodies or total Ig levels between offspring of immunized and non-immunized mothers on day 6 or 14 post-hatch, possibly reflecting a relatively short half-life of matAbs in altricial birds. Additionally, we found no evidence that nestlings from LPS-immunized mothers could avoid the growth-suppression that may result from activation of an inflammatory response. Unexpectedly, we found that control-nestlings from LPS-mothers had higher resting MR than control-nestlings of control-mothers. We attribute the increased MR to the costs associated with a general nonspecific enhancement of immune function in nestlings from LPS-immunized mothers. Consistent with enhanced immune function, nestlings of immunized mothers had a more robust inflammatory response to phytohaemagglutinin, and higher fledging success. Our results suggest maternal antigen exposure pre-laying can result in increased fitness for both mothers and offspring, depending on food availability.

雌性鸟类可通过卵黄将母源抗体（maternally-derived antibodies，matAb）传递至雏鸟体内。这类抗体被认为可提供被动免疫保护，使雏鸟免于因启动固有免疫应答而产生的代价。为验证雏鸟获得母源抗体能否带来能量收益，本研究于产卵前对成年雌性双色树燕（Tachycineta bicolor）分别注射脂多糖（lipopolysaccharide，LPS）或生理盐水（对照组，Control）以进行免疫刺激。雏鸟破壳后，每只雌鸟所育雏鸟中的一半于破壳后第8天接受LPS或生理盐水免疫，并在免疫后4小时内测定雏鸟的代谢率（metabolic rate，MR）。破壳后第6天和第14天时，免疫组与非免疫组母鸟的后代在LPS反应性抗体水平及总免疫球蛋白（Immunoglobulin，Ig）水平上均无显著差异，这一结果或反映出晚成雏鸟类体内母源抗体的半衰期相对较短。此外，本研究未发现来自LPS免疫母鸟的雏鸟能够避免因炎症应答激活而可能出现的生长抑制。出乎意料的是，我们观察到LPS免疫母鸟所产的对照组雏鸟，其静息代谢率高于对照组母鸟所产的对照组雏鸟。我们将该代谢率升高现象归因于这类雏鸟因免疫系统发生一般性非特异性增强而产生的生理成本。与免疫功能增强的研究结果一致，免疫组母鸟的雏鸟对植物血凝素（phytohaemagglutinin）的炎症应答更为强烈，且出巢成功率更高。本研究结果表明，产卵前母源抗原暴露可提升母鸟与后代的适合度，该效应的强弱取决于食物的可获得性。