Bats and Emerging Infections: An Ecological and Virological Puzzle

Molecular detection of trypanosomatids among cave-dwelling bats from Colombia

Bats play crucial roles in various ecosystems including caves. Although the presence of trypanosomatid species in bats has been documented in Colombia, their diversity in cave-dwelling bats remains unclear. This study aimed to characterize the frequency and diversity of protists from the family Trypanosomatidae circulating in bats from the Macaregua cave ecosystem in Santander, Colombia. A total of 112 specimens from the three permanently residing bat species were examined for trypanosomatid presence through the amplification and sequencing of a region of the 18S rRNA gene in blood samples. We report an overall trypanosomatid detection rate of 42.9% (n = 48), involving the three evaluated bat species: Carollia perspicillata (19/43, 44.2%), Natalus tumidirostris (17/39, 43.6%), and Mormoops megalophylla (12/30, 40.0%). The trypanosomatids were classified by amplicon sequencing and phylogenetic analysis as Trypanosoma spp. (33/112, 29.5%), Leishmania spp. (8/112, 7.1%), and Crithidia spp. (9/112, 8%). In addition, two individuals simultaneously carried more than one genus: Trypanosoma and Leishmania (MT087, C. perspicillata), and Trypanosoma and Crithidia (MT120, M. megalophylla). Some of the samples positive for trypanosomatids were characterized at the species level using the same method with the Cytochrome B gene, identifying Trypanosoma cruzi cruzi (TcI-III and TcBat), Trypanosoma cruzi marinkellei, and Leishmania braziliensis in the evaluated bats. We describe the presence of pathogenic trypanosomatids (T. cruzi cruzi, T. cruzi marinkellei, and L. braziliensis), as well as monoxenous trypanosomatids such as Crithidia spp. as the Trypanosomatidae protists carried by bats in cave ecosystems from Colombia. The discussion on how bats become infected by these parasites and their potential role in wild transmission cycles is provided below.

Detection and Prevalence of Coronaviruses in European Bats: A Systematic Review

Bats are known hosts for a wide range of coronaviruses (CoVs), including those that cause severe acute respiratory syndrome (SARS-CoV-1) and Middle East respiratory syndrome (MERS-CoV). With the emergence of the COVID-19 pandemic caused by the SARS-CoV-2 virus, it has become increasingly important to understand the diversity and prevalence of CoVs in bat populations. This systematic review aimed to compile studies that have sampled CoVs from bats across Europe and assessed various aspects related to the testing of bat samples, including the country where the bats were collected, the CoV genomic region studied, the CoV genera that were detected, and the identification of bat species that were found to be carrying CoV. We identified 30 studies that assessed CoVs presence in bats across multiple countries including Italy, Germany, and various other nations with one or two studies each, which tested them for CoVs using a variety of matrices. CoVs were found in nine genera of bats, and the genomic regions included RdRp, ORF1a gene, as well as full genome, detecting α- and/or β-CoVs, with most of them being detectable only in faeces. This review provides a comprehensive overview of the CoVs detected in bats across Europe and highlights the importance of continued surveillance and monitoring of bat populations for potential emerging zoonotic CoVs.

Genetic diversity and cross-species transmissibility of bat-associated picornaviruses from Spain

BACKGROUND

Emerging zoonotic diseases arise from cross-species transmission events between wild or domesticated animals and humans, with bats being one of the major reservoirs of zoonotic viruses. Viral metagenomics has led to the discovery of many viruses, but efforts have mainly been focused on some areas of the world and on certain viral families.

METHODS

We set out to describe full-length genomes of new picorna-like viruses by collecting feces from hundreds of bats captured in different regions of Spain. Viral sequences were obtained by high-throughput Illumina sequencing and analyzed phylogenetically to classify them in the context of known viruses. Linear discriminant analysis (LDA) was performed to infer likely hosts based on genome composition.

RESULTS

We found five complete or nearly complete genomes belonging to the family Picornaviridae, including a new species of the subfamily Ensavirinae. LDA suggested that these were true vertebrate viruses, rather than viruses from the bat diet. Some of these viruses were related to picornaviruses previously found in other bat species from distant geographical regions. We also found a calhevirus genome that most likely belongs to a proposed new family within the order Picornavirales, and for which genome composition analysis suggested a plant host.

CONCLUSIONS

Our findings describe new picorna-like viral species and variants circulating in the Iberian Peninsula, illustrate the wide geographical distribution and interspecies transmissibility of picornaviruses, and suggest new hosts for calheviruses.

Diversity of astroviruses in wild animals in Yunnan province, China

BACKGROUND

Astroviruses (AstVs) are single-stranded RNA viruses that have been detected in a wide range of mammals and birds. They are associated with numerous interspecies transmissions and viral recombination events, posing a threat to human and animal health.

METHODS

We collected 1,333 samples from wild animals, including bats, rodents, wild boars, and birds, from various states and cities in the Yunnan Province, China, between 2020 and 2023 to investigate the presence of AstVs. AstVs were detected using a polymerase chain reaction targeting the RdRp gene. Finally, the Molecular Evolutionary Genetics Analysis software was used to construct the phylogenetic tree.

RESULTS

The overall positivity rate for AstVs was 7.12% in four species, indicating their widespread occurrence in the region. High genetic diversity among AstVs was observed in different animal species, suggesting the potential for interspecies transmission, particularly among rodents and birds. Additionally, we identified a novel AstV strain and, for the first time, provided information on the presence of bastroviruses in Yunnan, China.

CONCLUSIONS

The widespread distribution and high genetic diversity of AstVs, along with the observed potential for interspecies transmission, highlight the importance of further investigation and surveillance in the region. The findings emphasize the need for increased attention to AstVs and their potential impact on human and animal health in Yunnan and other regions.

Peripheral immune responses to filoviruses in a reservoir versus spillover hosts reveal transcriptional correlates of disease

Several filoviruses, including Marburg virus (MARV), cause severe disease in humans and nonhuman primates (NHPs). However, the Egyptian rousette bat (ERB, Rousettus aegyptiacus), the only known MARV reservoir, shows no overt illness upon natural or experimental infection, which, like other bat hosts of zoonoses, is due to well-adapted, likely species-specific immune features. Despite advances in understanding reservoir immune responses to filoviruses, ERB peripheral blood responses to MARV and how they compare to those of diseased filovirus-infected spillover hosts remain ill-defined. We thus conducted a longitudinal analysis of ERB blood gene responses during acute MARV infection. These data were then contrasted with a compilation of published primate blood response studies to elucidate gene correlates of filovirus protection versus disease. Our work expands on previous findings in MARV-infected ERBs by supporting both host resistance and disease tolerance mechanisms, offers insight into the peripheral immunocellular repertoire during infection, and provides the most direct known cross-examination between reservoir and spillover hosts of the most prevalently-regulated response genes, pathways and activities associated with differences in filovirus pathogenesis and pathogenicity.

Detection of coronaviruses in insectivorous bats of Fore-Caucasus, 2021

Coronaviruses (CoVs) pose a huge threat to public health as emerging viruses. Bat-borne CoVs are especially unpredictable in their evolution due to some unique features of bat physiology boosting the rate of mutations in CoVs, which is already high by itself compared to other viruses. Among bats, a meta-analysis of overall CoVs epizootiology identified a nucleic acid observed prevalence of 9.8% (95% CI 8.7-10.9%). The main objectives of our study were to conduct a qPCR screening of CoVs' prevalence in the insectivorous bat population of Fore-Caucasus and perform their characterization based on the metagenomic NGS of samples with detected CoV RNA. According to the qPCR screening, CoV RNA was detected in 5 samples, resulting in a 3.33% (95% CI 1.1-7.6%) prevalence of CoVs in bats from these studied locations. BetaCoVs reads were identified in raw metagenomic NGS data, however, detailed characterization was not possible due to relatively low RNA concentration in samples. Our results correspond to other studies, although a lower prevalence in qPCR studies was observed compared to other regions and countries. Further studies should require deeper metagenomic NGS investigation, as a supplementary method, which will allow detailed CoV characterization.

High rates of antibodies against Toscana and Sicilian phleboviruses in common quail Coturnix coturnix birds

Introduction

Birds are involved natural cycle of a number of vector-borne viruses in both rural and urban areas. Toscana (TOSV) and Sicilian (SFSV) phleboviruses are sandfly-borne viruses in the genus Phlebovirus that can cause diseases in human. However, there is limited information on the role of the birds in sandfly-borne phleboviruses natural cycle and reservoirs ofthese viruses remain unknown.

Methods

In this study, we analyzed Common Quail (Coturnix coturnix) sera from Spain to identify the seroprevalence of these two phleboviruses. We tested respectively, 106 and 110 quail serum against TOSV and SFSV from 2018, 2019, and 2021 from two locations in northern Spain with using virus neutralization test.

Results

We identified high neutralizing antibody rates for SFSV (45.45%) and TOSV (42.45%) with yearly fluctuation.

Discussion

This is the first identification of SFSV and TOSV neutralizing antibodies in wild birds. High seroprevalence rates of TOSV and SFSV in quail birds raises the question whether birds have a role as amplifying hosts in the natural cycle of phleboviruses.

Virus Diversity, Abundance, and Evolution in Three Different Bat Colonies in Switzerland

Bats are increasingly recognized as reservoirs for many different viruses that threaten public health, such as Hendravirus, Ebolavirus, Nipahvirus, and SARS- and MERS-coronavirus. To assess spillover risk, viromes of bats from different parts of the world have been investigated in the past. As opposed to most of these prior studies, which determined the bat virome at a single time point, the current work was performed to monitor changes over time. Specifically, fecal samples of three endemic Swiss bat colonies consisting of three different bat species were collected over three years and analyzed using next-generation sequencing. Furthermore, single nucleotide variants of selected DNA and RNA viruses were analyzed to investigate virus genome evolution. In total, sequences of 22 different virus families were found, of which 13 are known to infect vertebrates. Most interestingly, in a Vespertilio murinus colony, sequences from a MERS-related beta-coronavirus were consistently detected over three consecutive years, which allowed us to investigate viral genome evolution in a natural reservoir host.

Emerging viruses: Cross-species transmission of coronaviruses, filoviruses, henipaviruses, and rotaviruses from bats

Emerging infectious diseases, especially if caused by bat-borne viruses, significantly affect public health and the global economy. There is an urgent need to understand the mechanism of interspecies transmission, particularly to humans. Viral genetics; host factors, including polymorphisms in the receptors; and ecological, environmental, and population dynamics are major parameters to consider. Here, we describe the taxonomy, geographic distribution, and unique traits of bats associated with their importance as virus reservoirs. Then, we summarize the origin, intermediate hosts, and the current understanding of interspecies transmission of Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2, Nipah, Hendra, Ebola, Marburg virus, and rotaviruses. Finally, the molecular interactions of viral surface proteins with host cell receptors are examined, and a comparison of these interactions in humans, intermediate hosts, and bats is conducted. This uncovers adaptive mutations in virus spike protein that facilitate cross-species transmission and risk factors associated with the emergence of novel viruses from bats.

Cospeciation of coronavirus and paramyxovirus with their bat hosts in the same geographical areas

Background

Bat-borne viruses are relatively host specific. We hypothesize that this host specificity is due to coevolution of the viruses with their hosts. To test this hypothesis, we investigated the coevolution of coronavirus and paramyxovirus with their bat hosts. Published nucleotide sequences of the RNA-dependent RNA polymerase (RdRp) gene of 60 coronavirus strains identified from 37 bat species, the RNA polymerase large (L) gene of 36 paramyxovirus strains from 29 bat species, and the cytochrome B (cytB) gene of 35 bat species were analyzed for coevolution signals. Each coevolution signal detected was tested and verified by global-fit cophylogenic analysis using software ParaFit, PACo, and eMPRess.

Results

Significant coevolution signals were detected in coronaviruses and paramyxoviruses and their bat hosts, and closely related bat hosts were found to carry closely related viruses.

Conclusions

Our results suggest that paramyxovirus and coronavirus coevolve with their hosts.

The Kidney-Associated Microbiome of Wild-Caught Artibeus spp. in Grenada, West Indies

Simple Summary

Bats are increasingly being recognized as important integrants of zoonotic disease cycles. Studying bat microbiomes could potentially contribute to the epidemiology of emerging infectious diseases in humans. Furthermore, studying the bat’s microbiome gives us the opportunity to look at the microbiome evolution in mammals. Bat microbiome studies have focused mainly on the gut microbiome, but little is known of the microbiome of the kidney, another potential source of disease transmission. Furthermore, many studies on microbiome found in the literature are based on captive animals, which usually alters the natural microbiome. Here, we analyzed kidney samples of wild-caught Artibeus spp., a fructivorous bat species from Grenada, West Indies, using metagenomics.

Abstract

Bats are capable of asymptomatically carrying a diverse number of microorganisms, including human pathogens, due to their unique immune system. Because of the close contact between bats and humans, there is a possibility for interspecies transmission and consequential disease outbreaks. Herein, high-throughput sequencing was used to determine the kidney-associated microbiome of a bat species abundant in Grenada, West Indies, Artibeus spp. Results indicate that the kidney of these bats can carry potential human pathogens. An endogenous retrovirus, Desmodus rotundus endogenous retrovirus isolate 824, phylogenetically related to betaretroviruses from rodents and New World primates, was also identified.

Emergence of Bat-Related Betacoronaviruses: Hazard and Risks

The current Coronavirus Disease 2019 (COVID-19) pandemic, with more than 111 million reported cases and 2,500,000 deaths worldwide (mortality rate currently estimated at 2.2%), is a stark reminder that coronaviruses (CoV)-induced diseases remain a major threat to humanity. COVID-19 is only the latest case of betacoronavirus (β-CoV) epidemics/pandemics. In the last 20 years, two deadly CoV epidemics, Severe Acute Respiratory Syndrome (SARS; fatality rate 9.6%) and Middle East Respiratory Syndrome (MERS; fatality rate 34.7%), plus the emergence of HCoV-HKU1 which causes the winter common cold (fatality rate 0.5%), were already a source of public health concern. Betacoronaviruses can also be a threat for livestock, as evidenced by the Swine Acute Diarrhea Syndrome (SADS) epizootic in pigs. These repeated outbreaks of β-CoV-induced diseases raise the question of the dynamic of propagation of this group of viruses in wildlife and human ecosystems. SARS-CoV, SARS-CoV-2, and HCoV-HKU1 emerged in Asia, strongly suggesting the existence of a regional hot spot for emergence. However, there might be other regional hot spots, as seen with MERS-CoV, which emerged in the Arabian Peninsula. β-CoVs responsible for human respiratory infections are closely related to bat-borne viruses. Bats are present worldwide and their level of infection with CoVs is very high on all continents. However, there is as yet no evidence of direct bat-to-human coronavirus infection. Transmission of β-CoV to humans is considered to occur accidentally through contact with susceptible intermediate animal species. This zoonotic emergence is a complex process involving not only bats, wildlife and natural ecosystems, but also many anthropogenic and societal aspects. Here, we try to understand why only few hot spots of β-CoV emergence have been identified despite worldwide bats and bat-borne β-CoV distribution. In this work, we analyze and compare the natural and anthropogenic environments associated with the emergence of β-CoV and outline conserved features likely to create favorable conditions for a new epidemic. We suggest monitoring South and East Africa as well as South America as these regions bring together many of the conditions that could make them future hot spots.

Seroprevalence of Toscana Virus and Sandfly Fever Sicilian Virus in European Bat Colonies Measured Using a Neutralization Test

Toscana phlebovirus (TOSV) and Sicilian phlebovirus (SFSV) are endemic in the Mediterranean area where they are transmitted to humans by infected sandflies. Vertebrates of several species have been postulated to act as reservoirs of these viruses, but convincing evidence is still awaited. Among them, bats have been suggested, however documented evidence is lacking. Here we tested a total of 329 bats belonging to eight species collected from twelve localities in southern Spain for the presence of neutralizing antibodies specific to TOSV and SFSV. Positive sera were detected in Schreiber’s long-fingered bat (Miniopterus schreibersii), mouse-eared Myotis (Myotis myotis), European free-tailed bat (Tadarida teniotis), and common serotine (Eptesicus serotinus) with the latter showing the highest prevalence rates for SFSV (22.6%) and TOSV (10%). There was no difference between females and males. Results suggest that bats are not likely to play a major role in the natural cycle of these two sandfly-borne phleboviruses. However, large breeding colonies of bats can be used as sentinels for surveillance of the presence of such viruses in a given locality. In addition, capture–recapture studies should be initiated in order to understand better the dynamics of TOSV and SFSV in bat populations.

Isolation and genetic properties of Bartonella in eastern bent-wing bats (Miniopterus fuliginosus) in Japan

The prevalence and genetic characteristics of Bartonella species in eastern bent-wing bats (Miniopterus fuliginosus) from Japan were investigated. Bartonella bacteria were isolated from 12/50 (24%) of bats examined. Analyses of sequence similarities of the citrate synthase gene (gltA) and RNA polymerase beta-subunit-encoding (rpoB) gene indicated that the isolates from M. fuliginosus were distinct from those present in known Bartonella species as the levels of similarity for both of the genes were lower than the cut-off values for species identification in Bartonella. A phylogenetic analysis of the gltA sequences revealed that the Miniopterus bat-associated strains fell into five genotypes (I to V). Though genotypes I to IV formed a clade with Bartonella from Miniopterus bats from Taiwan, genotype V made a monophyletic clade separate from other bat isolates. In a phylogenetic analysis with the concatenated sequences of the 16S rRNA, gltA, rpoB, cell division protein (ftsZ) gene, and riboflavin synthase gene (ribC), isolates belonging to genotypes I to IV clustered with Bartonella strains from Taiwanese Miniopterus bats, similar to the outcome of the phylogenetic analysis with gltA, whereas genotype V also made a monophyletic clade separate from other bat-associated Bartonella strains. The present study showed that M. fuliginosus in Japan harbor both genus Miniopterus-specific Bartonella suggesting to be specific to the bats in Japan.

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The prevalence of Bartonella in Miniopterus fuliginosus was 24%(12/50).

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M. fuliginosus in Japan harbored two novel Bartonella species in their blood.

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One Bartonella species was the genus Miniopterus-specific Bartonella.

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The other was distinct from other known bat-associated Bartonella.

Surveillance for Adenoviruses in Bats in Italy

Adenoviruses are important pathogens of humans and animals. Bats have been recognized as potential reservoirs of novel viruses, with some viruses being regarded as a possible zoonotic threat to humans. In this study, we report the detection and analysis of adenoviruses from different bat species in northern Italy. Upon sequence and phylogenetic analysis, based on a short diagnostic fragment of the highly-conserved DNA polymerase gene, we identified potential novel candidate adenovirus species, including an avian-like adenovirus strain. An adenovirus isolate was obtained in simian cell lines from the carcass of a Pipistrellus kuhlii, and the complete genome sequence was reconstructed using deep sequencing technologies. The virus displayed high nucleotide identity and virtually the same genome organization as the Pipistrellus pipistrellus strain PPV1, isolated in Germany in 2007. Gathering data on epidemiology and the genetic diversity of bat adenoviruses may be helpful to better understand their evolution in the mammalian and avian hosts.

Host-adapted Cryptosporidium and Enterocytozoon bieneusi genotypes in straw-colored fruit bats in Nigeria

Few data are available on the distribution and human infective potential of Cryptosporidium and Enterocytozoon bieneusi genotypes in bats. In this preliminary study, we collected 109 fecal specimens during April-July 2011 from a colony of straw-colored fruit bats (Eidolon helvum) in an urban park (Agodi Gardens) of Ibadan, Nigeria, and analyzed for Cryptosporidium spp., Giardia duodenalis and E. bieneusi using PCR targeting the small subunit rRNA gene, triosephosphate isomerase gene, and ribosomal internal transcribed spacer, respectively. Genotypes of these enteric parasites were determined by DNA sequencing of the PCR products. Altogether, 6 (5.5%), 0 and 16 (14.7%) specimens were positive for Cryptosporidium spp., G. duodenalis, and E. bieneusi, respectively. DNA sequence analysis of the PCR products indicated the presence of two novel Cryptosporidium genotypes named as bat genotype XIV (in 5 specimens) and bat genotype XV (in 1 specimen) and one known E. bieneusi genotype (Type IV in 1 specimen) and two novel E. bieneusi genotypes (Bat1 in 13 specimens and Bat2 in 2 specimens). In phylogenetic analysis of DNA sequences, the two novel Cryptosporidium genotypes were genetically related to Bat genotype II previously identified in fruit bats in China and Philippines, whereas the two novel E. bieneusi genotypes were genetically related to Group 5, which contains several known genotypes from primates. With the exception of Type IV, none of the Cryptosporidium and E. bieneusi genotypes found in bats in this study are known human pathogens. Thus, straw-colored fruit bats in Nigeria are mainly infected with host-adapted Cryptosporidium and E. bieneusi genotypes.

Detection of adenovirus, papillomavirus and parvovirus in Brazilian bats of the species Artibeus lituratus and Sturnira lilium

Bats play a significant role in maintaining their ecosystems through pollination, dispersal of seeds, and control of insect populations, but they are also known to host many microorganisms and have been described as natural reservoirs for viruses with zoonotic potential. The diversity of viruses in these animals remains largely unknown, however, because studies are limited by species, location, virus target, or sample type. Therefore, the aim of this study was to detect fragments of viral genomes in bat samples. We performed high-throughput sequencing analysis and specific PCR and RT-PCR on pools of anal and oropharyngeal swabs from Artibeus lituratus and Sturnira lilium collected in southern Brazil. As a result, a member of the family Adenoviridae related to human adenovirus C was detected in anal swabs from S. lilium. In addition, we detected a papillomavirus in an anal swab from A. lituratus. Our analyses also allowed the detection of adenoviruses and parvoviruses in oropharyngeal swabs collected from A. lituratus. These results increase our knowledge about viral diversity and illustrate the importance of conducting virus surveillance in bats.

Preface - Emerging Viruses: From Early Detection to Intervention

In the last decades, several viruses emerged, as the consequence of cross-species passage from animal reservoirs to human being. Emerging infections always represent a significant challenge for public health system as knowledge about specific pathogens are generally little while and no/few effective interventions are available. In this volume we explored special aspects of emerging infectious diseases including: the application of the theory of focality of diseases to infective syndrome; the human-animal inter-face focusing on influenza; the role of bats as main reservoir of emerging and novel human pathogens; Middle East Respiratory Syndrome Coronavirus (MERS-CoV) epidemiology and clinical presentation; immediate impact on human health of the last Zika virus outbreak occurred in Pacific Ocean and the Americas; the role and potential application of animal models for the study of emerging infections, to improve disease knowledge and for developing therapeutic drugs during ongoing outbreak.

Mortifères ou vivifiantes ? Les chauves-souris vues par des Autochtones aux Philippines

Pour les Occidentaux, les chauves-souris constituent des réservoirs à virus au pouvoir mortifère. Plusieurs groupes autochtones des Philippines, comme les Alangan mangyan et les Ayta, considèrent toutefois ces animaux comme des sources de vitalité et d’immunité, tandis que leurs voisins, les Ibaloy et les Blaan, les associent à des figures malodorantes et sanguinaires. La plupart du temps consommés, ces animaux sont traités avec respect en raison de leur place dans ces cosmologies. Quatre perceptions autochtones sont ici mises en perspective. Elles montrent comment « la science du concret » qui caractérise les savoirs indigènes s’élabore à partir d’observations méticuleuses et aboutit à des conclusions à la fois contrastées et convergentes avec celles des scientifiques. Bien avant ces derniers, les Autochtones ont cependant perçu la capacité des chauves-souris à vivre longtemps et à résister aux virus.