BACKGROUND: Filarial infections have been understudied in bats. Likewise, little is known about pathogens associated with the reproductive system in chiropterans. While semen quality is critical for reproductive success, semen-borne pathogens may contribute to reproductive failure. METHODS: For the first time we performed electroejaculation and used computer-assisted semen analysis to provide baseline data on semen quality in a parti-coloured bat (Vespertilio murinus). RESULTS: The semen quality values measured in the V. murinus male appeared high (semen concentration = 305.4 × 106/mL; progressive and motile sperm = 46.58 and 60.27%, respectively). As an incidental finding, however, microfilariae were observed in the bat semen examined. At necropsy, eight adult filarial worms, later genetically identified as Litomosa sp., were found in the peritoneal cavity, close to the stomach, of the same particoloured bat male dying as a result of dysmicrobia and haemorrhagic gastroenteritis in a wildlife rescue centre. Histopathology revealed microfilariae in the testicular connective tissue and the epidydimal connective and fat tissues. A PCR assay targeting cytochrome c oxidase subunit 1 confirmed that adult worms from the peritoneal cavity and testicular microfilariae were of the same filarial species. Mildly engorged argasid mite larvae attached to the bat skin proved negative for filarial DNA and the adult filarial worms proved negative for endosymbiont Wolbachia. CONCLUSION: While the standard filarial life cycle pattern involves a vertebrate definitive host and an invertebrate vector, represented by a blood-sucking ectoparasite, our finding suggests that microfilariae of this nematode species may also be semen-borne, with transmission intensity promoted by the polygynous mating system of vespertilionid bats in which an infected male mates with many females during the autumn swarming. Presence of microfilariae may be expected to decrease semen quality and transmission via this route may challenge the success of reproductive events in females after mating. Further investigation will be necessary to better understand the bat-parasite interaction and the life cycle of this filarial worm.

• Keywords
• Chiroptera, Vespertilio murinus, Wolbachia, electroejaculation, filariasis, semen quality parameters, semen-borne pathogens,
• Publication type
• Journal Article MeSH
• Case Reports MeSH

Bats are natural reservoirs of numerous coronaviruses, including the potential ancestor of SARS-CoV-2. Knowledge concerning the interaction between coronaviruses and bat cells is sparse. We investigated the ability of primary cells from Rhinolophus and Myotis species, as well as of established and novel cell lines from Myotis myotis, Eptesicus serotinus, Tadarida brasiliensis, and Nyctalus noctula, to support SARS-CoV-2 replication. None of these cells were permissive to infection, not even the ones expressing detectable levels of angiotensin-converting enzyme 2 (ACE2), which serves as the viral receptor in many mammalian species. The resistance to infection was overcome by expression of human ACE2 (hACE2) in three cell lines, suggesting that the restriction to viral replication was due to a low expression of bat ACE2 (bACE2) or the absence of bACE2 binding in these cells. Infectious virions were produced but not released from hACE2-transduced M. myotis brain cells. E. serotinus brain cells and M. myotis nasal epithelial cells expressing hACE2 efficiently controlled viral replication, which correlated with a potent interferon response. Our data highlight the existence of species-specific and cell-specific molecular barriers to viral replication in bat cells. These novel chiropteran cellular models are valuable tools to investigate the evolutionary relationships between bats and coronaviruses. IMPORTANCE Bats are host ancestors of several viruses that cause serious disease in humans, as illustrated by the ongoing SARS-CoV-2 pandemic. Progress in investigating bat-virus interactions has been hampered by a limited number of available bat cellular models. We have generated primary cells and cell lines from several bat species that are relevant for coronavirus research. The various permissivities of the cells to SARS-CoV-2 infection offered the opportunity to uncover some species-specific molecular restrictions to viral replication. All bat cells exhibited a potent entry-dependent restriction. Once this block was overcome by overexpression of human ACE2, which serves at the viral receptor, two bat cell lines controlled well viral replication, which correlated with the inability of the virus to counteract antiviral responses. Other cells potently inhibited viral release. Our novel bat cellular models contribute to a better understanding of the molecular interplays between bat cells and viruses.

• Keywords
• SARS-CoV-2, bat cells, coronavirus, innate immunity,
• MeSH
• Angiotensin-Converting Enzyme 2 genetics   MeSH
• Chiroptera * virology   MeSH
• Species Specificity MeSH
• Spike Glycoprotein, Coronavirus metabolism   MeSH
• Humans MeSH
• Virus Replication * MeSH
• SARS-CoV-2 * physiology   MeSH
• Receptors, Virus metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Angiotensin-Converting Enzyme 2 MeSH
• Spike Glycoprotein, Coronavirus MeSH
• spike protein, SARS-CoV-2 MeSH Browser
• Receptors, Virus MeSH

Co-existence of bats with a wide range of infectious agents relates to their co-evolutionary history and specific physiology. Here, we examined blood samples collected during hibernation and the post-hibernation period to assess the influence of trypanosomes and babesias on the health status of 50 Noctule bats (Nyctalus noctula) using nested PCR. The impact of blood parasites on health was assessed by analysis of haematology and blood chemistry parameters in 21 bats. Prevalence of trypanosomes (Trypanosoma dionisii and T. vespertilionis) and babesia (Babesia vesperuginis) was 44% and 8%, respectively. Analysis of blood parameters indicated impact of babesia on acid-base balance. Blood chemistry parameters showed a significant decrease in total dissolved carbon dioxide and bicarbonate, increased anion gap, and no change in blood pH, suggesting compensated metabolic acidosis. Adverse effects of babesia were only apparent in hibernating bats. Our results suggest differences in the pathogenicity of trypanosomes and babesia in bats. While trypanosomes in general had no significant impact on the health status, we observed alterations in the blood acid-base balance in Babesia-infected bats during hibernation. Despite being infected, Babesia-positive bats survived hibernation without showing any clinical signs.

• Keywords
• Babesia vesperuginis, Chiroptera, Schizotrypanum, Trypanosoma dionisii, Trypanosoma vespertilionis, acid–base balance, blood chemistry, haematology,
• Publication type
• Journal Article MeSH

BACKGROUND: The success of animal reproduction is impacted by a trade-off between energetic costs and mortality associated with immediate vs. future reproductive attempts. The reproductive strategies of European insectivorous bats differ from common mammalian standards due to the use of delayed fertilisation. Phenology of bat reproduction, including length of pregnancy, which may vary in the same species at different latitudes, between years at the same site or between individuals within a colony, is influenced by ecological conditions. To assess factors influencing the course of pregnancy, we evaluated levels of blood progesterone in 20 female common noctule bats Nyctalus noctula. The bats were individually tagged and randomly divided into two groups with different hibernation ending points (i.e. a control group vs. a treatment group with one-week longer hibernation). Following emergence from hibernation, the bats were kept in a wooden box at a stable temperature of 22 °C. RESULTS: The majority of females gave birth to a single neonate (65%), but one female aborted her pups 2 days before the first successful births of other females. Based on development of progesterone concentration, we were able to define a number of different reproduction strategies, i.e. females with single offspring or twins, and females with supposed resorption of one embryo (embryonic mortality after implantation of the developing fertilised egg). Progesterone levels were much higher in females with two embryos during the first part of gestation and after birth. Progesterone levels were at their highest mid-gestation, with no difference between females carrying one or two foetuses. Length of gestation differed significantly between the two groups, with the longer hibernation (treatment) group having a roughly two-day shorter gestation period. CONCLUSIONS: Female N. noctula are able to manipulate their litter size to balance immediate and future reproduction success. The estimated gestation length of approx. 49-days appears to be standard for N. noctula, with females optimising their thermoregulatory behaviour to keep the length of gestation as close to the standard as possible.

• Keywords
• Body weight, Chiroptera, Embryo resorption, Gestation, Progesterone,
• Publication type
• Journal Article MeSH

BACKGROUND: Palearctic bats host a diversity of lyssaviruses, though not the classical rabies virus (RABV). As surveillance for bat rabies over the Palearctic area covering Central and Eastern Europe and Siberian regions of Russia has been irregular, we lack data on geographic and seasonal patterns of the infection. RESULTS: To address this, we undertook serological testing, using non-lethally sampled blood, on 1027 bats of 25 species in Bulgaria, the Czech Republic, Poland, Russia and Slovenia between 2014 and 2018. The indirect enzyme-linked immunosorbent assay (ELISA) detected rabies virus anti-glycoprotein antibodies in 33 bats, giving an overall seroprevalence of 3.2%. Bat species exceeding the seroconversion threshold included Myotis blythii, Myotis gracilis, Myotis petax, Myotis myotis, Murina hilgendorfi, Rhinolophus ferrumequinum and Vespertilio murinus. While Myotis species (84.8%) and adult females (48.5%) dominated in seropositive bats, juveniles of both sexes showed no difference in seroprevalence. Higher numbers tested positive when sampled during the active season (10.5%), as compared with the hibernation period (0.9%). Bat rabies seroprevalence was significantly higher in natural habitats (4.0%) compared with synanthropic roosts (1.2%). Importantly, in 2018, we recorded 73.1% seroprevalence in a cave containing a M. blythii maternity colony in the Altai Krai of Russia. CONCLUSIONS: Identification of such "hotspots" of non-RABV lyssavirus circulation not only provides important information for public health protection, it can also guide research activities aimed at more in-depth bat rabies studies.

• Keywords
• Chiroptera, Europe, Siberia, blood samples, rabies, seroprevalence,
• MeSH
• Chiroptera virology   MeSH
• Ecosystem MeSH
• Rhabdoviridae Infections epidemiology   MeSH
• Caves MeSH
• Lyssavirus isolation & purification   MeSH
• Antibodies, Viral blood   MeSH
• Seasons MeSH
• Seroepidemiologic Studies MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe epidemiology   MeSH
• Russia epidemiology   MeSH
• Names of Substances
• Antibodies, Viral MeSH

The greater mouse-eared bat (Myotis myotis) is a flagship species for the protection of hibernation and summer maternity roosts in the Western Palearctic region. A range of pathogenic agents is known to put pressure on populations, including the white-nose syndrome fungus, for which the species shows the highest prevalence and infection intensity of all European bat species. Here, we perform analysis of blood parameters characteristic for the species during its natural annual life cycle in order to establish reference values. Despite sexual dimorphism and some univariate differences, the overall multivariate pattern suggests low seasonal variation with homeostatic mechanisms effectively regulating haematology and blood biochemistry ranges. Overall, the species displayed a high haematocrit and haemoglobin content and high concentration of urea, while blood glucose levels in swarming and hibernating bats ranged from hypo- to normoglycaemic. Unlike blood pH, concentrations of electrolytes were wide ranging. To conclude, baseline data for blood physiology are a useful tool for providing suitable medical care in rescue centres, for studying population health in bats adapting to environmental change, and for understanding bat responses to stressors of conservation and/or zoonotic importance.

• MeSH
• Chiroptera blood   physiology   MeSH
• Hematocrit standards   MeSH
• Hematologic Tests standards   MeSH
• Hibernation MeSH
• Climate MeSH
• Reference Values MeSH
• Seasons MeSH
• Sentinel Species physiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Arctic Regions epidemiology   MeSH

BACKGROUND: Emergence of both viral zoonoses from bats and diseases that threaten bat populations has highlighted the necessity for greater insights into the functioning of the bat immune system. Particularly when considering hibernating temperate bat species, it is important to understand the seasonal dynamics associated with immune response. Body temperature is one of the factors that modulates immune functions and defence mechanisms against pathogenic agents in vertebrates. To better understand innate immunity mediated by phagocytes in bats, we measured respiratory burst and haematology and blood chemistry parameters in heterothermic greater mouse-eared bats (Myotis myotis) and noctules (Nyctalus noctula) and homeothermic laboratory mice (Mus musculus). RESULTS: Bats displayed similar electrolyte levels and time-related parameters of phagocyte activity, but differed in blood profile parameters related to metabolism and red blood cell count. Greater mouse-eared bats differed from mice in all phagocyte activity parameters and had the lowest phagocytic activity overall, while noctules had the same quantitative phagocytic values as mice. Homeothermic mice were clustered separately in a high phagocyte activity group, while both heterothermic bat species were mixed in two lower phagocyte activity clusters. Stepwise regression identified glucose, white blood cell count, haemoglobin, total dissolved carbon dioxide and chloride variables as the best predictors of phagocyte activity. White blood cell counts, representing phagocyte numbers available for respiratory burst, were the best predictors of both time-related and quantitative parameters of phagocyte activity. Haemoglobin, as a proxy variable for oxygen available for uptake by phagocytes, was important for the onset of phagocytosis. CONCLUSIONS: Our comparative data indicate that phagocyte activity reflects the physiological state and blood metabolic and cellular characteristics of homeothermic and heterothermic mammals. However, further studies elucidating trade-offs between immune defence, seasonal lifestyle physiology, hibernation behaviour, roosting ecology and geographic patterns of immunity of heterothermic bat species will be necessary. An improved understanding of bat immune responses will have positive ramifications for wildlife and conservation medicine.

• Keywords
• Bats, Blood, Innate immunity, Phagocytosis, Respiratory burst, Torpor,
• MeSH
• Blood Chemical Analysis MeSH
• Chiroptera blood   immunology   MeSH
• Behavior, Animal physiology   MeSH
• Phagocytes immunology   MeSH
• Erythrocyte Count MeSH
• Body Temperature * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

In underground hibernacula temperate northern hemisphere bats are exposed to Pseudogymnoascus destructans, the fungal agent of white-nose syndrome. While pathological and epidemiological data suggest that Palearctic bats tolerate this infection, we lack knowledge about bat health under pathogen pressure. Here we report blood profiles, along with body mass index (BMI), infection intensity and hibernation temperature, in greater mouse-eared bats (Myotis myotis). We sampled three European hibernacula that differ in geomorphology and microclimatic conditions. Skin lesion counts differed between contralateral wings of a bat, suggesting variable exposure to the fungus. Analysis of blood parameters suggests a threshold of ca. 300 skin lesions on both wings, combined with poor hibernation conditions, may distinguish healthy bats from those with homeostatic disruption. Physiological effects manifested as mild metabolic acidosis, decreased glucose and peripheral blood eosinophilia which were strongly locality-dependent. Hibernating bats displaying blood homeostasis disruption had 2 °C lower body surface temperatures. A shallow BMI loss slope with increasing pathogen load suggested a high degree of infection tolerance. European greater mouse-eared bats generally survive P. destructans invasion, despite some health deterioration at higher infection intensities (dependant on hibernation conditions). Conservation measures should minimise additional stressors to conserve constrained body reserves of bats during hibernation.

• MeSH
• Ascomycota physiology   MeSH
• Chiroptera blood   microbiology   physiology   MeSH
• Hibernation * MeSH
• Body Mass Index MeSH
• Host-Pathogen Interactions * MeSH
• Skin Diseases blood   microbiology   pathology   veterinary   MeSH
• Mycoses blood   microbiology   pathology   veterinary   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH