Corticosterone, inflammation, immune status and telomere length in frigatebird nestlings facing a severe herpesvirus infection.

Manrico Sebastiano,Olivier Chastel,Marcel Eens,Frederic Angelier,David Costantini,Kévin Pineau

doi:10.1093/conphys/cow073

Abstract

Herpesvirus outbreaks are common in natural animal populations, but little is known about factors that favour the infection and its consequences for the organism. In this study, we examined the pathophysiological consequences of a disease probably attributable to herpesvirus infection for several markers of immune function, corticosterone, telomere length and inflammation. In addition, we assessed whether any markers used in this study might be associated with the occurrence of visible clinical signs of the disease and its impact on short-term survival perspectives. To address our questions, in spring 2015, we collected blood samples from nestlings of the magnificent frigatebird (Fregata magnificens) that were free of any clinical signs or showed visible signs of the disease. We found that the plasma concentration of haptoglobin was strongly associated with the infection status and could predict probabilities of survival. We also found that nestlings with clinical signs had lower baseline corticosterone concentrations and similar telomere length compared with healthy nestlings, whereas we did not find any association of the infection status with innate immune defenses or with nitric oxide concentration. Overall, our results suggest that the plasma concentration of haptoglobin might be a valuable tool to assess survival probabilities of frigatebird nestlings facing a herpesvirus outbreak.

Highlights

Organisms have evolved a range of specific and non-specific mechanisms of protection against pathogens, there are circumstances that make the organism unable to control the activity of a given pathogen (Klimpel, 1996; van Boven and Weissing, 2004)
Little is known about the causes and pathophysiological consequences of herpesvirus infection in wild animals (Goldberg et al, 1990)
In birds, elevated concentrations of corticosterone (CORT; the main avian glucocorticoid) have detrimental effects on nestling growth, behaviour and immunity (Kitaysky et al, 2003; Rubolini et al, 2005) and can even increase the generation of reactive oxygen species (Costantini et al, 2011). Both chronic stressful conditions and generation of reactive oxygen species via CORT negatively affect the dynamics of the telomeres, long repetitive non-coding sequences of DNA located at the ends of chromosomes, which can play a major role in ageing processes (Blackburn, 1991)

Summary

Introduction

Organisms have evolved a range of specific and non-specific mechanisms of protection against pathogens, there are circumstances (e.g. food shortage, high stress level) that make the organism unable to control the activity of a given pathogen (Klimpel, 1996; van Boven and Weissing, 2004). In birds, elevated concentrations of corticosterone (CORT; the main avian glucocorticoid) have detrimental effects on nestling growth, behaviour and immunity (Kitaysky et al, 2003; Rubolini et al, 2005) and can even increase the generation of reactive oxygen species (Costantini et al, 2011) Both chronic stressful conditions and generation of reactive oxygen species via CORT negatively affect the dynamics of the telomeres (von Zglinicki, 2002; Kotrschal et al, 2007; Haussmann et al, 2012; Quirici et al, 2016), long repetitive non-coding sequences of DNA located at the ends of chromosomes, which can play a major role in ageing processes (Blackburn, 1991). Telomeres, considered as valuable indicators of cell health (Counter, 1996), might reflect the individual’s ability to cope with stressful conditions (Kotrschal et al, 2007) and predict lifespan, reproductive outcome or survival perspective in birds (Haussmann et al, 2005; Heidinger et al, 2012; Angelier et al, 2013)

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