Carotenoids modulate the effect of coccidian infection on the condition and immune response in moulting house sparrows

Abstract

SUMMARYIn the present study, we experimentally manipulated coccidian parasitism and dietary carotenoid availability in a fully factorial experiment in male house sparrows (Passer domesticus Linnaeus), and tested whether carotenoid supplementation reduces the cost of parasitism in terms of condition, moult and immune responses. We found that coccidians have a significant but transient negative effect on body mass, which can be reduced if birds have access to carotenoid supplementation in their diet. Experimental manipulation had no significant effect on the moulting parameters of the birds measured following coccidian infestation and during the whole moulting period. Carotenoid supplementation increased the plasma carotenoid concentration in both infested and medicated birds treated with a coccidiostatic drug; however, after two months exposure to parasites, plasma carotenoid concentration increased only in the carotenoid-supplemented and medicated group whereas no difference was observed between the carotenoid-supplemented and infested and non-supplemented groups. On the contrary, coccidian infestation was not affected by carotenoid supplementation. Experimental infestation decreased the antibody response to sheep red blood cells (SRBCs), although no significant effect was observed in the capacity of the birds to respond to a mitogenic challenge with phytohemagglutinin. Within the experimentally infested groups birds with carotenoid-supplemented food tended to have an increased anti-SRBC humoral immune response. The positive correlation between coccidian infestation and the strength of the humoral immune response against SRBCs in the non-supplemented and infested groups indicates that this part of the immune system plays an important role in defence against these parasites.

Seasonal Patterns and Relationships among Coccidian Infestations, Measures of Oxidative Physiology, and Immune Function in Free-Living House Sparrows over an Annual Cycle

“…We collected about 250 mL of blood into heparinized capillary tubes within 30 min of capture, and immediately after sampling, we made blood smears by spreading a drop of blood on a microscope slide. The blood samples were transported in cooling bags to the laboratory for further processing within 8 h. The birds were placed in a large outdoor aviary (4 m # 5 m # 2.5 m; length # width # height) situated at the campus of Babeş-Bolyai University, Cluj-Napoca, for a total of 2 d. Following this acclimatization period in the aviary, the house sparrows were placed in individual cages to quantify the level of coccidian infestation by measuring the rate of oocyst shedding over two additional days (for details, see Pap et al 2009). Infestation intensity was expressed as number of oocysts per gram of feces, and the average of the 2 d was used in the analyses.…”

“…Generally, house sparrows and other free-living birds are negatively affected by coccid- ians in terms of condition, measures of oxidative physiology, and immune function (Hõrak et al 2004;Pap et al 2009Pap et al , 2011Sepp et al 2012a;Bókony et al 2014). However, most of these studies were conducted on birds with acute (experimental) infestation, which may explain the differences between this study and other studies.…”

“…Previous studies of parasite-induced immune activation have shown that individuals with high parasite loads tend to produce stronger immune responses and larger changes in oxidative state (i.e., Sorci and Faivre 2009). High loads of coccidian parasites have this effect on some measures of immune and oxidative physiology (Hõrak et al 2004;Baeta et al 2008;Pap et al 2009Pap et al , 2011Sepp et al 2012a). However, it remains unknown whether these patterns would hold over the year in wild conditions, since these studies were based on birds from the breeding season or from captive individuals.…”

“…The leukocyte profile is a general assay of the health status, and the H/L ratio is a general measure of stress (reviewed by Davis et al 2008). Most of these variables of oxidative physiology, immune function, and stress index have been shown to be affected by coccidians in wild and captive birds (Hõrak et al 2004;Pap et al 2009Pap et al , 2011Sepp et al 2012a;Bókony et al 2014). Our study design allowed us to test the hypothesis that seasonal change in immune function and oxidative physiology are related to naturally occurring levels of parasite infection.…”

Birds receiving extra carotenoids keep singing during the sickness phase induced by inflammation

“…For example, the environmental conditions determining the availability of dietary micronutrients with immunomodulatory effects can alleviate the cost of mounting an immunoresponse. Carotenoids are a clear example in this respect (Blount et al 2003;McGraw and Ardia 2003;Smith et al 2007;Pap et al 2009;Sepp et al 2011;McGraw and Toomey 2013). These pigments have attracted the attention of ecologists because of their dual role.…”