European Bat Research Articles

Cross-Protection of Inactivated Rabies Vaccines for Veterinary Use against Bat Lyssaviruses Occurring in Europe.

Human rabies vaccines have been shown to induce partial protection against members of phylogroup I bat lyssaviruses. Here, we investigated the capacity of a widely used rabies inactivated vaccine (Rabisin, Boehringer-Ingelheim) for veterinary use to cross-protect mice experimentally infected with European bat lyssavirus 1 (EBLV-1b), European bat lyssavirus 2 (EBLV-2), and Bokeloh bat lyssavirus (BBLV) occurring in Europe. For each lyssavirus, we investigated the efficacy of two different doses of vaccine against two viral doses administrated by either central or peripheral routes. In parallel, seroconversion following pre-exposure vaccination was investigated. In this study, we demonstrated that the three investigated bat isolates were pathogenic, even at low dose, when inoculated by the central route but were not/less pathogenic when administrated peripherally. The Rabisin vaccine was capable of significantly cross-protecting mice inoculated intramuscularly with EBLV-1b and EBLV-2 and intracerebrally with BBLV. The level of rabies neutralizing antibodies induced by the Rabisin was quite high against the bat lyssaviruses, but with no significant differences between immunization with 1 and 5 IU/dose. The study emphasizes that the quality of rabies-inactivated vaccines for veterinary use is of utmost importance to optimize the cross-protection of pets against phylogroup I bat lyssaviruses occurring in Europe.

High Throughput Bioacoustic Monitoring and Phenology of the Greater Noctule Bat (Nyctalus lasiopterus) Compared to Other Migratory Species

Conventional monitoring tools are seldom effective for studying the ecology of rare and elusive mammals. In the present study, we use automated ultrasound detectors to provide information about seasonal activity of the greater noctule bat (Nyctalus lasiopterus), the largest and one of least known European bats. We selected localities within Central Europe with diverse geomorphological contexts, including rivers of different sizes and mountain passes. The study demonstrates the capability of the automatic recording approach to achieve bioacoustic discrimination of this species, but also pointed to the persistent need of integrating results from automatic classification software applications with the feedback from manual approaches. The high throughput capacity of the assay proved to be efficient, and the regular occurrence of the species was identified at two localities. These locations are associated with two known and intensely used migratory corridors of winged animals going through Vltava River valley and Cervenohorske Saddle in Jeseniky mountains, as illustrated also by the activity patterns of other migratory species. Together with the occurrence of spring and autumn peaks in activity, these findings are in concordance with the plesiomorphic condition in pipistrelloid bats, showing also migratory behavior, and represent further indirect evidence of migration of the greater noctule. This pattern could be facilitated by the trophic niche of the species, involving predation of migrating songbirds. Differences in phenology of migratory species observed at particular sites likely mirror position of the locality in relation to migration flyways, seasonal and geographic variation in prey availability and energy demands etc. Further application of bioacoustic monitoring and other tools is necessary to obtain detailed information about the range and movement ecology of the species in higher latitudes.

Current Rabies Vaccines Do Not Confer Protective Immunity against Divergent Lyssaviruses Circulating in Europe.

The use of the rabies vaccine for post-exposure prophylaxis started as early as 1885, revealing a safe and efficient tool to prevent human rabies cases. Preventive vaccination is the basis for the control of canine-mediated rabies, which has already been eliminated from extensive parts of the world, including Europe. Plans to eliminate canine-mediated human rabies by 2030 have been agreed upon by international organisations. However, rabies vaccines are not efficacious against some divergent lyssaviruses. The presence in European indigenous bats of recently described lyssaviruses, which are not neutralised by antibody responses to existing vaccines, as well as the declaration of an imported case of an African lyssavirus, which also escapes vaccine-derived protection, leaves the European health authorities unable to provide efficacious protective vaccines to some potential situations of human exposure. All these circumstances highlight the need for a universal pan-lyssavirus rabies vaccine, able to prevent human rabies in all circumstances.

Environmental exposure to non-essential trace elements in two bat species from urbanised (Tadarida teniotis) and open land (Miniopterus schreibersii) areas in Italy

Bats are particularly suited as bioindicators of trace element pollution due to their longevity and their position in the trophic chain. In this study, the concentrations of ten non-essential trace elements (Al, As, Ba, Cd, Hg, Pb, Sb, Sr, Th, Tl) were determined in the tissues (whole body, skin-fur, skinned body, liver, kidney and bone) of lactant Tadarida teniotis from a nursery colony in Rome. A large number of bats from this nursery died before fledging and had bone deformities and fractures. The concentrations of non-essential trace elements in bone and whole body were also analysed in adult specimens of Miniopterus schreibersii from a colony located in a natural park in Northern Italy. In lactant T. teniotis, the Pb concentration decreased in the following order: bone>liver>skinned body>whole body>skin-fur>kidney, and exceeded the toxic threshold associated with negative effects reported for different mammalian species. The levels of the other non-essential trace elements were within a range indicative of low environmental contamination in both species. Significant interspecies differences (P < 0.05) were observed for concentrations of Pb and Ba, higher in the bones of T. teniotis, and of Cd, Hg and Sr, higher in the bones of M. schreibersii. In lactant T. teniotis, the different sources of Pb exposure, through inhalation and/or food, may represent a potential threat to the colony of this synanthropic European bat.

An inter-laboratory comparison to evaluate the technical performance of rabies diagnosis lateral flow assays

As in previous years, the European Union Reference Laboratory (EURL) for rabies organised in 2018 an Inter-laboratory trial (ILT) on rabies diagnosis. Contrarily to past years, the 2018 ILT did not aim to evaluate the performance of participating laboratories, but the technical performance of new rapid tests. Two lateral Flow Assays (LFA), namely the Anigen® and the CDIA™ Rabies Virus Antigen Rapid Test” (commercialized by Bionote and Creative Diagnostics Cie respectively), were evaluated together with the Fluorescent Antibody Test (FAT). One panel of virus samples (including RABV as well as EBLV1a, EBLV-1b, and EBLV2 strains) was sent to participating laboratories to compare results obtained with these different techniques.The study revealed that the FAT provided a good agreement toward expected results for both negative/positive samples (99.1%). The Anigen® test produced similar results to the FAT, with only one false negative result (0.5%) reported by all participants and a concordance of 100% for all but one sample demonstrating a good inter-laboratory reproducibility of the Anigen® batch. The CDIA™ test produced reproducible results for Rabies Virus (RABV) samples only. However, it hardly detected the Bokeloh Bat Lyssavirus (BBLV) and the European Bat Lyssaviruses types 1b and 2 (EBLV-1b and EBLV-2) in most laboratories resulting in a moderate inter-laboratory concordance (58.4%–82.7%) for these lyssaviruses.The two LFAs provided reliable and reproducible results on all RABV samples (100%) but lead to heterogeneous performances with other lyssaviruses leading to different levels of diagnostic/analytical sensitivity, specificity. The study confirmed that LFAs should be used with caution and that their validation are of upmost importance before any use in laboratories.

First records of the European free-tailed bat Tadarida teniotis (Rafinesque, 1814) in Slovenia

An acoustic survey of bats was conducted throughout 2016 on the slopes of the hill Črna griža near Kozina, and from the end of August 2016 to the end of October 2017 on a small Griško polje plateau close to the village of Dolenja vas near Senožeče — both sites are located in the south-west of Slovenia. Echolocation calls of Tadarida teniotis were recorded at both sites. T. teniotis was recorded near Kozina during 11 nights from April to October 2016, but it was rare, with its 38 passes constituting just 0.53% of all bat passes. It was even rarer near Dolenja vas where it was recorded twice only on the hill Veliki Ognjivec — in April and October 2017 — where constituting only 0.0001% of all bat passes. Both sites are located on the northern border of T. teniotis Submediterranean range. T. teniotis is the 31st bat species recorded in Slovenia and the 30th bat species currently living in the country.

Hypsugopoxvirus: A Novel Poxvirus Isolated from Hypsugo savii in Italy.

Interest in bat-related viruses has increased considerably during the last decade, leading to the discovery of a rising number of new viruses in several bat species. Poxviridae are a large, diverse family of DNA viruses that can infect a wide range of vertebrates and invertebrates. To date, only a few documented detections of poxviruses have been described in bat populations on three different continents (America, Africa, and Australia). These viruses are phylogenetically dissimilar and have diverse clinical impacts on their hosts. Herein, we report the isolation, nearly complete genome sequencing, and annotation of a novel poxvirus detected from an insectivorous bat (Hypsugo savii) in Northern Italy. The virus is tentatively named Hypsugopoxvirus (HYPV) after the bat species from which it was isolated. The nearly complete genome size is 166,600 nt and it encodes 161 genes. Genome analyses suggest that HYPV belongs to the Chordopoxvirinae subfamily, with the highest nucleotide identity (85%) to Eptesipoxvirus (EPTV) detected from a microbat Eptesicus fuscus in WA, USA, in 2011. To date, HYPV represents the first poxvirus detected in bats in Europe; thus, its viral ecology and disease associations should be investigated further.

Fatty acid profiles of the European migratory common noctule bat (Nyctalus noctula).

In animals, fatty acids (FA) are essential as structural components in membranes and for energy storage in adipocytes. Here, we studied the relative proportions of FA in a mammal with extreme changes in metabolic rates. Common noctule bats (Nyctalus noctula) switch from energetically demanding long-distance migration at high metabolic rates to regular torpor with extremely low metabolic rates. We found that composition of FA categories differed between adipose tissue types (white adipose tissue (WAT) vs brown adipose tissue (BAT)) and muscle tissue types (skeletal vs heart), but not between sexes. We found oleic acid to be the most abundant FA in all studied tissues. Concentrations of polyunsaturated FA (PUFA) were not always higher in muscular tissue compared with adipocyte tissue, even though high concentrations of PUFA are considered beneficial for low body temperatures in torpor. In all tissues, we observed a high content in monounsaturated fatty acids (MUFA), possibly to compensate for a low PUFA content in the diet. Ratios of ω6/ω3 were lower in the heart than in skeletal muscles of common noctules. Three FA (palmitic, oleic, and linoleic acid) accounted for about 70% of the FA in adipose tissue, which is similar to proportions observed in migrating birds, yet migrating birds generally have a higher PUFA content in muscle and adipose tissues than bats. Bats seem to contrast with other mammals in having a high MUFA content in all tissues. We conclude that FA profiles of bats differ largely from those of most cursorial mammals and instead are-with the exception of MUFA-similar to those of migrating birds.

Variant maps for bat echolocation call identification algorithms

ABSTRACT Automated ultrasonic recordings are widely used in basic and applied research to detect the presence of bats. Often, algorithms for the automated identification of species are based on a pre-processing of acoustic information that involves the generation of spectrograms. Even though this approach is technically advanced, recent surveys highlight substantially high failure rates to identify species correctly, which urges for improved processes. Here, we tested an entirely new method, in particular, the transformation of ultrasonic recordings into variant maps. To compare this method with a spectrogram-based method, we used a database consisting of 160 echolocation calls from eight European bat species, including species of the genus Myotis that are inherently difficult to separate based on echolocation calls. For non-Myotis species, both methods led to a 100% correct identification rate, while for Myotis species the use of variant maps led to a lower identification rate of 85.3% compared to 91.1% that was achieved with a spectrogram-based method. However, a combination of both methods could lead to an identification rate of 94.1% for Myotis species. This result suggests combining our approach with spectrogram-based techniques to improve the automated identification of species based on acoustic information.

Numerous cold arousals and rare arousal cascades as a hibernation strategy in European Myotis bats.

Hibernating bats optimise the duration of torpor bouts and arousals in relation to hibernaculum microclimatic conditions and fat reserves. Clustering has significant physiological and ecological benefits, promoting successful hibernation of individuals. Such aggregations may help maintain optimal temperatures, allowing better energy utilisation than in solitarily bats. However, aroused bats in a cluster could conceivably disturb those still hibernating, starting an energy-demanding arousal process. Our study was conducted over two winters in two different hibernacula (cave and mine) in the Czech Republic, where Greater mouse-eared bats (Myotis myotis) have previously been diagnosed with white-nose syndrome. In 118 arousal episodes we recorded 193 individual arousals in which a warming phase was observed, 135 (69.9%) being cold arousals, where bats ceased increasing their body temperatures at ≤ 10 °C. The remaining arousals were standard normothermic arousals, where body (fur) surface temperatures reached > 20 °C. Cold arousals occurred during the mid- and late hibernation periods, suggesting they were a response to disturbance by a neighbour in the same cluster. Arousal cascades, where bats aroused in series, were rare (12.7%) and reached a maximum in mid-January. Our data suggest that Myotis bats prolong their torpor bouts using numerous cold arousals but few arousal cascades. Upon arrival of a bat, the clustered bats show tolerance to disturbing by conspecifics.

The Balkan long-eared bat (Plecotus kolombatovici) occurs in Italy – first confirmed record and potential distribution

In recent years, many cryptic species of bats have been discovered thanks to the application of molecular techniques. The several long-eared bat species (genus Plecotus) occurring in Europe show a marked morphological similarity and occur in sympatry, so that when confusion may arise, molecular approaches have prime importance to establish the actual specific identity. Italy represents a diversity hotspot for bats in Europe, hosting 35 species, among them four Plecotus species. In this study we report on the first confirmed record of the Balkan’s long-eared bat Plecotus kolombatovici for peninsular Italy, review previous unconfirmed records and analyse the species’ potential distribution in the country using a modelling approach. The species’ potential distribution is strongly associated with warm summer temperatures and relatively high winter precipitations, typical of Mediterranean climate. The modelling exercise we did highlights that P. kolombatovici may occur in much of the Italian territory, including the Tyrrhenian coast and on many islands that border it. We therefore argue that P. kolombatovici presence has been so far overlooked due to the morphological resemblance of this species with the grey long-eared bat P. austriacus. Comprehensive surveys are needed to ascertain the actual distribution and establish the conservation status in Italy of this poorly known species to adopt effective legal and practical conservation measures.

Host Phylogeny, Geographic Overlap, and Roost Sharing Shape Parasite Communities in European Bats

How multitrophic relationships between wildlife communities and their ectoparasitic vectors interact to shape the diversity of vector-borne microorganisms is poorly understood. Nested levels of dependence among microbes, vectors, and vertebrate hosts may have complicated effects on both microbial community assembly and evolution. We examined Bartonella sequences from European bats and their ectoparasites with a combination of network analysis, Bayesian phylogenetics, tip-association and cophylogeny tests, and linear regression to understand the ecological and evolutionary processes that shape parasite communities. We detected seven bat-ectoparasite-Bartonella communities that can be differentiated based on bat families and roosting patterns. Tips of the Bartonella tree were significantly clustered by host taxonomy and geography. We also found significant evidence of evolutionary congruence between bat host and Bartonella phylogenies, indicating that bacterial species have evolved to infect related bat species. Exploring these ecological and evolutionary associations further, we found that sharing of Bartonella species among bat hosts was strongly associated with host phylogenetic distance and roost sharing and less strongly with geographic range overlap. Ectoparasite sharing between hosts was strongly predicted by host phylogenetic distance, roost sharing, and geographic overlap but had no additive effect on Bartonella sharing. Finally, historical Bartonella host-switching was more frequent for closely related bats after accounting for sampling bias among bat species. This study helps to disentangle the complex ecology and evolution of Bartonella bacteria in bat species and their arthropod vectors. Our work provides insight into the important mechanisms that partition parasite communities among hosts, particularly the effect of host phylogeny and roost sharing, and could help to elucidate the evolutionary patterns of other diverse vector-borne microorganisms.

Molecular characterization of the rabies virus' nucleoprotein in dogs from Arequipa, Peru

. To characterize the nucleoprotein (N) and establish the origin of the rabies virus in dogs coming from Arequipa. Thirty samples of nervous tissue from the departments of Arequipa and Puno were analyzed. Total RNA was extracted from the samples and cDNA was synthesized to amplify the nucleoprotein gene, sequence it, and perform bioinformatics analysis. . A defined group was formed with respect to the external group (European bat lyssavirus). This group was classified into two subgroups, one constituted by samples coming from Puno and Arequipa (subgroup A), and another one by samples from Puno (subgroup B), exhibiting a nucleotide identity of 99.9% in subgroup A. This group was classified in two subgroups, one constituted by samples coming from Puno and Arequipa (subgroup A), and another one by samples from Puno (subgroup B), observing a nucleotide identity of 99.9% in subgroup A. The groupings of viral sequences show that the cases of canine rabies reported in Arequipa are the result of the expansion of canine rabies from the endemic region of Puno.

The Itinerant Natterer: Dynamics of Summer Roost Occupancy by Myotis nattereri (Chiroptera, Vespertilionidae)

Natterer's bat Myotis nattereri is one of the least known European bats. Understanding its patterns of movement between roosts is an important aspect of assessing the relative value of different types of roost for conservation of the species. We determined patterns of movement of Natterer's bat between roosts by radio-tracking successive animals from the same colonies during summer (May to September). For one maternity colony comprising 65 adult females, the attic of a large mediaeval church was the main roost site, accounting for 88% of radio-located bat days. The two other maternity colonies tracked comprised about 35 adult females each and used from 15 to 25 roost sites, some containing multiple roosts. For these two colonies, up to six roost sites per colony accounted for about 80% of bat occupancy days in any one summer and for each colony, roost home ranges for roosts used by subgroups of at least two bats together covered 0.4 km2. Although bats made frequent movements between roosts there was no apparent interchange between adjacent colonies and no overlap in the range used by adjacent colonies. Bats changed roosts every 3.0 days on average, moving 510 m (median) to an alternative roost. They departed late and returned early to roosts. Colonies assembled or disintegrated into larger or smaller groups occupying diverse roosts during summer, but there was high social cohesion between colony members. Bats that separated into subgroups from mid-summer (mid-July) onwards later roosted together again. Natterer's bat exhibits high behavioural flexibility in the type of roosts used: of two adjacent maternity colonies, one used mostly tree roosts and the other mostly buildings. However, both roosted mainly in roofs during early summer (late May to mid-July). Tree roosts were significantly preferred to those in buildings when ambient external maximum temperatures were ≥ 30°C or mean temperatures fell below 14°C. Natterer's bat appears to depend on the availability of a number of roosts of different types. Parturition roosts, roosts in heavily timbered barns and roosts within core roosting areas, potentially up to 1.2 km distant from the parturition roost, should have highest conservation priority but conservation management should guard against any roost loss.

An example of ecological traps for bats in the urban environment

Urban environments have semi-natural features that attract some groups of wild animals such as bats, which belong to one of the most diverse groups of mammals remaining in cities. There are limited numbers of examples of ecological traps for bats in urban environments. We describe a case of high bat mortality in one concrete building (Kharkiv city, 50° 0′ N, 36° 15′ E Ukraine) where we found 157 carcasses of Nyctalus noctula killed by cats over the winter 2014–2015. We suppose that cats killed mainly healthy individuals with a higher ratio of females than in the total sample size. We are describing this case of bat mortality as an ecological trap. Moreover, we presume that the real number of bats killed by free-ranging cats could be higher, up to several hundreds per winter. In addition, it is a specific way for disease transfer that could affect public health. European bats are under special protection and in such cases, conservationist and animal welfare activists attempt to protect bat hibernation aggregations from any negative impacts.

Unraveling the role of Myotis myotis in the ecology and transmission of rabies-related lyssaviruses (RRLVs)

Purpose: Insectivorous bats have been found to carry a variety of Rabies-Related Lyssaviruses (RRLVs) across Europe, among which European bat Lyssavirus 1 (EBLV-1) is the most widely distributed. Despite the majority of lethal infections are reported from serotine bats, serological data suggest that other species might have a role in the ecology of this pathogen. EBLV-1 has been associated with spillover events to humans, domestic and wildlife animals, causing a neurological disease clinically indistinguishable from classical rabies. Unraveling its ecology would then be crucial in predicting and mitigating associated risks for public health. Methods & Materials: During 2012-2018, we investigated the role of Myotis myotis in the maintenance and transmission of EBLV-1, through the longitudinal screening of roosts for neutralizing antibodies and viral shedding. Five neighboring maternal colonies were investigated in Northern Italy, whose connectivity was assessed using genetic and capture-recapture studies. Results: Antibodies neutralizing EBLV-1 were detected yearly, confirming that M. myotis are constantly exposed to the virus in the area and do survive the infection. In addition, longitudinal data revealed wide oscillations of antibodies during a single reproductive season, suggesting waning of antibodies and waves of infection. All colonies showed similar serological trends over consecutive years. Indeed, we found evidence for genetic panmixia at the nuclear and mitochondrial level and confirmed the movement of adult females between roosts. Conclusion: Altogether, our results support the role of M. myotis as natural host for an EBLV1-like RRLV. While this bat species usually inhabits underground sites in the Mediterranean areas, M. myotis is a strictly house dweller species in northern areas, with all colonies investigated in this study being located in church roofs. Based on both serological and virological findings, we suggest that the risk for human exposure to the virus is limited, with viral excretion restricted to short predictable windows of time. We predict that this study will be useful to secure public health while maintaining a positive relationship between humans and these large vesper bats, whose critical role in the control of pest insects is well recognized in the area.

Mechanisms for lyssavirus persistence in non-synanthropic bats in Europe: insights from a modeling study

Bats are natural reservoirs of the largest proportion of viral zoonoses among mammals, thus understanding the conditions for pathogen persistence in bats is essential to reduce human risk. Focusing on the European Bat Lyssavirus subtype 1 (EBLV-1), causing rabies disease, we develop a data-driven spatially explicit metapopulation model to investigate EBLV-1 persistence in Myotis myotis and Miniopterus schreibersii bat species in Catalonia. We find that persistence relies on host spatial structure through the migratory nature of M. schreibersii, on cross-species mixing with M. myotis, and on survival of infected animals followed by temporary immunity. The virus would not persist in the single colony of M. myotis. Our study provides for the first time epidemiological estimates for EBLV-1 progression in M. schreibersii. Our approach can be readily adapted to other zoonoses of public health concern where long-range migration and habitat sharing may play an important role.

Babesial infection in the Madagascan flying fox, Pteropus rufus \xc9. Geoffroy, 1803

BackgroundBabesiae are erythrocytic protozoans, which infect the red blood cells of vertebrate hosts to cause disease. Previous studies have described potentially pathogenic infections of Babesia vesperuginis in insectivorous bats in Europe, the Americas and Asia. To date, no babesial infections have been documented in the bats of Madagascar, or in any frugivorous bat species worldwide.ResultsWe used standard microscopy and conventional PCR to identify babesiae in blood from the endemic Madagascan flying fox (Pteropus rufus). Out of 203 P. rufus individuals captured between November 2013 and January 2016 and screened for erythrocytic parasites, nine adult males (4.43%) were infected with babesiae. Phylogenetic analysis of sequences obtained from positive samples indicates that they cluster in the Babesia microti clade, which typically infect felids, rodents, primates, and canids, but are distinct from B. vesperuginis previously described in bats. Statistical analysis of ecological trends in the data suggests that infections were most commonly observed in the rainy season and in older-age individuals. No pathological effects of infection on the host were documented; age-prevalence patterns indicated susceptible-infectious (SI) transmission dynamics characteristic of a non-immunizing persistent infection.ConclusionsTo our knowledge, this study is the first report of any erythrocytic protozoan infecting Madagascan fruit bats and the first record of a babesial infection in a pteropodid fruit bat globally. Given the extent to which fruit bats have been implicated as reservoirs for emerging human pathogens, any new record of their parasite repertoire and transmission dynamics offers notable insights into our understanding of the ecology of emerging pathogens.

Snake predation on bats in Europe: new cases and a regional assessment

Abstract Among reptiles only snakes are known to frequently feed on bats and even inside this group chiropterophagy is rare, with most records being noted in the tropics. In the temperate region and especially in Europe, only a handful of cases have been described. Here, we report further cases of bat predation in underground habitats of Bulgaria, highlighting the importance of the Aesculapian snake (Zamenis longissimus) predation on bats in the Western Palearctic. Until now, 11 species of bats have been recorded as preys of snakes in Europe. Our observations are the first records of snake hunting on Mediterranean horseshoe bats (Rhinolophus euryale) and on greater mouse-eared bats (Myotis myotis) in Europe, and only the third to fourth observation of underground predation. The observation in a short time of two incidences of hunting in a fairly small area, coupled with the regular presence of snakes in cave environments, may suggest a more common bat hunting habit for Aesculapian snakes. Bat predation of snakes in the Balkan region (or in the Mediterranean) certainly is more common than previously assumed. The number of records may increase substantially with targeted search during crepuscular and night hours in the entrance area of underground bat shelters.

Immune response of hibernating European bats to a fungal challenge.

ABSTRACTImmunological responses of hibernating mammals are suppressed at low body temperatures, a possible explanation for the devastating effect of the white-nose syndrome on hibernating North American bats. However, European bats seem to cope well with the fungal causative agent of the disease. To better understand the immune response of hibernating bats, especially against fungal pathogens, we challenged European greater mouse-eared bats (Myotis myotis) by inoculating the fungal antigen zymosan. We monitored torpor patterns, immune gene expressions, different aspects of the acute phase response and plasma oxidative status markers, and compared them with sham-injected control animals at 30 min, 48 h and 96 h after inoculation. Torpor patterns, body temperatures, body masses, white blood cell counts, expression of immune genes, reactive oxygen metabolites and non-enzymatic antioxidant capacity did not differ between groups during the experiment. However, zymosan injected bats had significantly higher levels of haptoglobin than the control animals. Our results indicate that hibernating greater mouse-eared bats mount an inflammatory response to a fungal challenge, with only mild to negligible consequences for the energy budget of hibernation. Our study gives a first hint that hibernating European bats may have evolved a hibernation-adjusted immune response in order to balance the trade-off between competent pathogen elimination and a prudent energy-saving regime.