Determinants of defence strategies of a hibernating European bat species towards the fungal pathogen Pseudogymnoascus destructans. (June 2021)

• Record Type: Journal Article
• Authors: Fritze, Marcus; Puechmaille, Sebastien J.; Costantini, David; Fickel, Jörns; Voigt, Christian C.; Czirják, Gábor Á.
• Is Part Of: Developmental and comparative immunology. Volume 119(2021)
• Publication Date: 2021-06
• Subjects: White-nose disease -- Hibernation immunology -- Acute phase response -- Haptoglobin -- Oxidative stress -- Tolerance -- Chiroptera; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2021.104017
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Pseudogymnoascus destructans (Pd), the causative agent of white-nose syndrome in North America, has decimated bat populations within a decade. The fungus impacts bats during hibernation when physiological functions, including immune responses, are down-regulated. Studies have shown that Pd is native to Europe, where it is not associated with mass mortalities. Moreover, genomic and proteomic studies indicated that European bats may have evolved an effective immune defence, which is lacking in North American bats. However, it is still unclear which defence strategy enables European bats to cope with the pathogen. Here, we analyzed selected physiological and immunological parameters in torpid, Pd infected European greater mouse-eared bats ( Myotis myotis ) showing three different levels of infection (asymptomatic, mild and severe symptoms). From a subset of the studied bats we tracked skin temperatures during one month of hibernation. Contrasting North American bats, arousal patterns remained unaffected by Pd infections in M. myotis . In general, heavier M. myotis aroused more often from hibernation and showed less severe disease symptoms than lean individuals; most likely because heavy bats were capable of reducing the Pd load more effectively than lean individuals. In the blood of severely infected bats, we found higher gene expression levels of an inflammatory cytokine (IL-1β), but lower levels of an acute phase protein (haptoglobin), reactive oxygen metabolites (ROMs) and plasma non-enzymatic antioxidant capacity (OXY) compared to conspecifics with lower levels of infection. We conclude that M. myotis, and possibly also other European bat species, tolerate Pd infections during torpor by using selected acute phase response parameters at baseline levels, yet without arousing from torpor and without synthesizing additional immune molecules. Highlights: Hibernating European bats infected with the fungal pathogen Pseudogymnoascus destructans do not interrupt the torpor state due to the infection European bats induce an immune response during torpor and use baseline levels of immune effectors in their blood circulation Individuals with higher energy storage generally arouse more often from torpor and show less disease symptoms compared to lean conspecifics