Gervasi Stephanie S, Burgan Sarah C, Hofmeister Erik, Unnasch Thomas R, Martin Lynn B
Monell Chemical Senses Center, Philadelphia, PA 19104, USA
Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA.
Proc Biol Sci. 2017 Jul 26;284(1859). doi: 10.1098/rspb.2017.1090.
Glucocorticoid stress hormones, such as corticosterone (CORT), have profound effects on the behaviour and physiology of organisms, and thus have the potential to alter host competence and the contributions of individuals to population- and community-level pathogen dynamics. For example, CORT could alter the rate of contacts among hosts, pathogens and vectors through its widespread effects on host metabolism and activity levels. CORT could also affect the intensity and duration of pathogen shedding and risk of host mortality during infection. We experimentally manipulated songbird CORT, asking how CORT affected behavioural and physiological responses to a standardized West Nile virus (WNV) challenge. Although all birds became infected after exposure to the virus, only birds with elevated CORT had viral loads at or above the infectious threshold. Moreover, though the rate of mortality was faster in birds with elevated CORT compared with controls, most hosts with elevated CORT survived past the day of peak infectiousness. CORT concentrations just prior to inoculation with WNV and anti-inflammatory cytokine concentrations following viral exposure were predictive of individual duration of infectiousness and the ability to maintain physical performance during infection (i.e. tolerance), revealing putative biomarkers of competence. Collectively, our results suggest that glucocorticoid stress hormones could directly and indirectly mediate the spread of pathogens.
糖皮质激素应激激素，如皮质酮（CORT），对生物体的行为和生理有深远影响，因此有可能改变宿主能力以及个体对种群和群落层面病原体动态的贡献。例如，CORT可通过其对宿主代谢和活动水平的广泛影响，改变宿主、病原体和媒介之间的接触率。CORT还可能影响感染期间病原体排出的强度和持续时间以及宿主死亡风险。我们通过实验操纵鸣禽的CORT，探究CORT如何影响对标准化西尼罗河病毒（WNV）攻击的行为和生理反应。尽管所有鸟类在接触病毒后都被感染，但只有CORT升高的鸟类病毒载量达到或高于感染阈值。此外，虽然CORT升高的鸟类死亡率比对照组更快，但大多数CORT升高的宿主在传染性峰值日之后存活下来。接种WNV之前的CORT浓度以及病毒暴露后的抗炎细胞因子浓度可预测个体的感染持续时间以及感染期间维持身体机能的能力（即耐受性），揭示了假定的能力生物标志物。总体而言，我们的结果表明糖皮质激素应激激素可直接和间接介导病原体的传播。
