Oxidative stress biomarkers are associated with visible clinical signs of a disease in frigatebird nestlings

Abstract

Infectious diseases are one of the most common threats for both domestic and wild animals, but little is known about the effects on the physiological condition and survival of wild animals. Here, we have tested for the first time in a wild vertebrate facing a viral disease possibly due to herpesvirus (i) whether nestlings with either low levels of oxidative damage or high levels of antioxidant protection are less susceptible to develop visible clinical signs, (ii) whether the disease is associated with the nestlings’ oxidative status, (iii) whether the association between the disease and oxidative status is similar between males and females (iv), and whether cloacal and tracheal swabs might be used to detect herpesvirus. To address our questions, we took advantage of a population of Magnificent frigatebirds (Fregata magnificens) whose nestlings have experienced high mortality rates in recent times. Our work shows that (i) blood lipid oxidative damage is associated with observable clinical signs and survival probabilities of nestling frigatebirds, and (ii) that high glutathione levels in red blood cells are associated with the emergence of visible clinical signs of the disease. Our work provides evidence that differences in the oxidative status of nestlings might underlie individual health and survival.

Food supplementation protects Magnificent frigatebird chicks against a fatal viral disease

“…Two pictures of each bird were taken from the same distance and same position before the start and at the end of the experiment. The pictures were used to classify the chicks based on severity of visible clinical signs (“ no signs ,” “ mild ,” and “ severe ;” Figure ), which are important to assess the progress of a herpesvirus‐induced disease (e.g., Thomas, Hunter, & Atkinson, ) and are associated with diverse physiological markers of health status (Sebastiano et al., ,c). This approach enabled us to determine any changes in chicks’ health status: did not have any clinical signs at the beginning of the experiment but showed them at the end of the experiment (“ new sick ”); never showed clinical signs (“ always healthy ”); showed a decrease in clinical signs over the experiment (“ better condition ”); did not show any changes in the severity of visible clinical signs (“ same severity ”).…”

“…This frigatebird population is considered as one of the most important along the Atlantic coast of South America (Nuss, Caio, Ignacio, & Nelson, 2016). In recent years, recurrent episodes of frigatebird chicks' mortality due to disease outbreaks that first appeared in (de Thoisy et al, 2009) have turned into massive mortality episodes (85-95% of chicks) that occur annually (Sebastiano et al, 2017b). The disease is characterized by the appearance of visible clinical signs (i.e., skin crusts) that can rapidly spread all over the chicks' body, giving in most cases no chances of recovery (Sebastiano et al, 2017c;Sebastiano et al, 2018).…”

Nothing in modern biology makes sense except in the light of ecology and biodiversity conservation

“…Although the work has not been finished yet, data collected so far have already allowed us to either identify or discard potential factors relevant for the progress of the disease. For example, nestlings with severe clinical signs of the disease suffer higher molecular oxidative damage and inflammation than those not showing any clinical signs ( Sebastiano et al , 2017b , c ). Markers of oxidative damage and inflammation were also significantly associated with the short-term probability of survival of nestlings.…”

Extraction Process, Component Analysis, and In Vitro Antioxidant, Antibacterial, and Anti-Inflammatory Activities of Total Flavonoid Extracts from Abutilon theophrasti Medic. Leaves

“…Oxidative stress, which is an important factor that leads to aging and diseases, can be produced by excessive free radicals [ 1 – 4 ]. Therefore, the elimination of harmful free radicals is an effective approach for balancing the internal environment and preventing related diseases.…”