Isolation and characterization of three mammalian orthoreoviruses from European bats

Characterization of a mammalian orthoreovirus isolated from the large flying fox, Pteropus vampyrus, in Indonesia

Fruit bats serve as an important reservoir for many zoonotic pathogens, including Nipah virus, Hendra virus, Marburg virus and Lyssavirus. To gain a deeper insight into the virological characteristics, pathogenicity and zoonotic potential of bat-borne viruses, recovery of infectious viruses from field samples is important. Here, we report the isolation and characterization of a mammalian orthoreovirus (MRV) from a large flying fox (Pteropus vampyrus) in Indonesia, which is the first detection of MRV in Southeast Asia. MRV was recovered from faecal samples of three different P. vampyrus in Central Java. Nucleotide sequence analysis revealed that the genome of the three MRV isolates shared more than 99% nucleotide sequence identity. We tentatively named one isolated strain as MRV12-52 for further analysis and characterization. Among 10 genome segments, MRV12-52 S1 and S4, which encode the cell-attachment protein and outer capsid protein, had 93.6 and 95.1% nucleotide sequence identities with known MRV strains, respectively. Meanwhile, the remaining genome segments of MRV12-52 were divergent with 72.9-80.7 % nucleotide sequence identities. Based on the nucleotide sequence of the S1 segment, MRV12-52 was grouped into serotype 2, and phylogenetic analysis demonstrated evidence of past reassortment events. In vitro characterization of MRV12-52 showed that the virus efficiently replicated in BHK-21, HEK293T and A549 cells. In addition, experimental infection of laboratory mice with MRV12-52 caused severe pneumonia with 75% mortality. This study highlights the presence of pathogenic MRV in Indonesia, which could serve as a potential animal and public health concern.

Detection of Dengue Virus 1 and Mammalian Orthoreovirus 3, with Novel Reassortments, in a South African Family Returning from Thailand, 2017

In July 2017, a family of three members, a 46-year-old male, a 45-year-old female and their 8-year-old daughter, returned to South Africa from Thailand. They presented symptoms consistent with mosquito-borne diseases, including fever, headache, severe body aches and nausea. Mosquito bites in all family members suggested recent exposure to arthropod-borne viruses. Dengue virus 1 (Genus Orthoflavivirus) was isolated (isolate no. SA397) from the serum of the 45-year-old female via intracerebral injection in neonatal mice and subsequent passage in VeroE6 cells. Phylogenetic analysis of this strain indicated close genetic identity with cosmopolitan genotype 1 DENV1 strains from Southeast Asia, assigned to major lineage K, minor lineage 1 (DENV1I_K.1), such as GZ8H (99.92%) collected in November 2018 from China, and DV1I-TM19-74 isolate (99.72%) identified in Bangkok, Thailand, in 2019. Serum samples from the 46-year-old male yielded a virus isolate that could not be confirmed as DENV1, prompting unbiased metagenomic sequencing for virus identification and characterization. Illumina sequencing identified multiple segments of a mammalian orthoreovirus (MRV), designated as Human/SA395/SA/2017. Genomic and phylogenetic analyses classified Human/SA395/SA/2017 as MRV-3 and assigned a tentative genotype, MRV-3d, based on the S1 segment. Genomic analyses suggested that Human/SA395/SA/2017 may have originated from reassortments of segments among swine, bat, and human MRVs. The closest identity of the viral attachment protein σ1 (S1) was related to a human isolate identified from Tahiti, French Polynesia, in 1960. This indicates ongoing circulation and co-circulation of Southeast Asian and Polynesian strains, but detailed knowledge is hampered by the limited availability of genomic surveillance. This case represents the rare concurrent detection of two distinct viruses with different transmission routes in the same family with similar clinical presentations. It highlights the complexity of diagnosing diseases with similar sequelae in travelers returning from tropical areas.

Isolation and identification of a novel porcine-related recombinant mammalian orthoreovirus type 3 strain from cattle in Guangxi Province, China

The Mammalian orthoreovirus (MRV) infects various mammals, including humans, and is linked to gastrointestinal, respiratory, and neurological diseases. A recent outbreak in Liuzhou, Guangxi, China, led to the isolation of a new MRV strain, GXLZ2301, from fecal samples. This strain replicates in multiple cell lines and forms lattice-like structures. Infected cells exhibit single-cell death and syncytia formation. The virus's titers peaked at 107.2 TCID50/0.1 mL in PK-15 and BHK cells, with the lowest at 103.88 TCID50/0.1 mL in A549 cells. Electron microscopy showed no envelope with a diameter of about 70 nm. Genetic analysis revealed GXLZ2301 as a recombinant strain with gene segments from humans, cows, and pigs, similar to type 3 MRV strains from Italy (2015-2016). Pathogenicity tests indicated that while the bovine MRV strain did not cause clinical symptoms in mice, it caused significant damage to the gut, lungs, liver, kidneys, and brain. The emergence of this MRV strain may pose a threat to the health of animals and humans, and it is recommended that its epidemiology and recombination be closely monitored.

The genomic characteristics and pathogenicity of a mammalian orthoreovirus within a new lineage from wild pika in plateau

Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years. Herein, we isolated a new mammalian orthoreovirus (MRV), Pika/MRV/GCCDC7/2019 (PMRV-GCCDC7), in the Qinghai-Tibet Plateau wild pika (Ochotona curzoniae). Though the PMRV-GCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length, the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis. The results of cellular susceptibility, species tropism, and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines (A549, Huh7, HCT, and LoVo) and six non-human cell lines, including Vero-E6, LLC-MK2, BHK-21, N2a, MDCK, and RfKT cell, derived from diverse mammals, i.e. monkey, mice, canine and bat, which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts. Infection of BALB/c mice with PMRV-GCCDC7 via intranasal inoculation led to relative weight loss, lung tissue damage and inflammation with the increase of virus titer, but no serious respiratory symptoms and death occurred. The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.

Main causes of death of free-ranging bats in Turin province (North-Western Italy): gross and histological findings and emergent virus surveillance

BACKGROUND

Bats are recognized as reservoir species for multiple viruses. However, little is known on bats' health and mortality. Thus, this study aimed to investigate the main causes of death of bats from Turin province (North-western Italy) and to describe gross and histopathological lesions potentially associated with the presence of selected bat viruses.

RESULTS

A total of 71 bats belonging to 9 different species of the families Vespertilionidae and Molossidae were necropsied and samples of the main organs were submitted to histopathological examination. Also, aliquots of the small intestine, liver, spleen, lung, and brain were collected and submitted to biomolecular investigation for the identification of Coronaviridae, Poxviridae, Reoviridae (Mammalian orthoreovirus species), Rhabdoviridae (Vaprio ledantevirus and Lyssavirus species) and Kobuvirus. The majority of bats died from traumatic lesions due to unknown trauma or predation (n = 40/71, 56.3%), followed by emaciation (n = 13/71,18.3%). The main observed gross lesions were patagium and skin lesions (n = 23/71, 32.4%), forelimbs fractures (n = 15/71, 21.1%) and gastric distension (n = 10/71,14.1%). Histologically, the main lesions consisted of lymphoplasmacytic pneumonia (n = 24/71, 33.8%), skin/patagium dermatitis (n = 23/71, 32.4%), liver steatosis and hepatitis (n = 12, 16.9%), and white pulp depletion in the spleen (n = 7/71, 9.8%). Regarding emergent bat viruses, only poxvirus (n = 2, 2.8%) and orthoreovirus (n = 12/71, 16.9%) were detected in a low percentage of bats.

CONCLUSIONS

Trauma is the main lesion observed in bats collected in Turin province (North-western Italy) associated with forelimb fractures and the detected viral positivity rate seems to suggest that they did not represent a threat for human health.

Paired immunoglobulin-like receptor B is an entry receptor for mammalian orthoreovirus

Mammalian orthoreovirus (reovirus) infects most mammals and is associated with celiac disease in humans. In mice, reovirus infects the intestine and disseminates systemically to cause serotype-specific patterns of disease in the brain. To identify receptors conferring reovirus serotype-dependent neuropathogenesis, we conducted a genome-wide CRISPRa screen and identified paired immunoglobulin-like receptor B (PirB) as a receptor candidate. Ectopic expression of PirB allowed reovirus binding and infection. PirB extracelluar D3D4 region is required for reovirus attachment and infectivity. Reovirus binds to PirB with nM affinity as determined by single molecule force spectroscopy. Efficient reovirus endocytosis requires PirB signaling motifs. In inoculated mice, PirB is required for maximal replication in the brain and full neuropathogenicity of neurotropic serotype 3 (T3) reovirus. In primary cortical neurons, PirB expression contributes to T3 reovirus infectivity. Thus, PirB is an entry receptor for reovirus and contributes to T3 reovirus replication and pathogenesis in the murine brain.

Isolation and characterization of mammalian orthoreovirus from bats in the United States

Mammalian orthoreovirus (MRV) infects many mammalian species including humans, bats, and domestic animals. To determine the prevalence of MRV in bats in the United States, we screened more than 900 bats of different species collected during 2015-2019 by a real-time reverse-transcription polymerase chain reaction assay; 4.4% bats tested MRV-positive and 13 MRVs were isolated. Sequence and phylogenetic analysis revealed that these isolates belonged to four different strains/genotypes of viruses in Serotypes 1 or 2, which contain genes similar to those of MRVs detected in humans, bats, bovine, and deer. Further characterization showed that these four MRV strains replicated efficiently on human, canine, monkey, ferret, and swine cell lines. The 40/Bat/USA/2018 strain belonging to the Serotype 1 demonstrated the ability to infect and transmit in pigs without prior adaptation. Taken together, this is evidence for different genotypes and serotypes of MRVs circulating in US bats, which can be a mixing vessel of MRVs that may spread to other species, including humans, resulting in cross-species infections.

Investigation of the Virome and Characterization of Issyk-Kul Virus from Swedish Myotis brandtii Bats

Bats are reservoirs for many different viruses, including some that can be transmitted to and cause disease in humans and/or animals. However, less is known about the bat-borne viruses circulating in Northern European countries such as in Sweden. In this study, saliva from Myotis brandtii bats, collected from south-central Sweden, was analyzed for viruses. The metagenomic analysis identified viral sequences belonging to different viral families, including, e.g., Nairoviridae, Retroviridae, Poxviridae, Herpesviridae and Siphoviridae. Interestingly, through the data analysis, the near-complete genome of Issyk-Kul virus (ISKV), a zoonotic virus within the Nairoviridae family, was obtained, showing 95-99% protein sequence identity to previously described ISKVs. This virus is believed to infect humans via an intermediate tick host or through contact with bat excrete. ISKV has previously been found in bats in Europe, but not previously in the Nordic region. In addition, near full-length genomes of two novel viruses belonging to Picornavirales order and Tymoviridae family were characterized. Taken together, our study has not only identified novel viruses, but also the presence of a zoonotic virus not previously known to circulate in this region. Thus, the results from these types of studies can help us to better understand the diversity of viruses circulating in bat populations, as well as identify viruses with zoonotic potential that could possibly be transmitted to humans.

Highly Multiplexed Serology for Nonhuman Mammals

Emerging infectious diseases represent a serious and ongoing threat to humans. Most emerging viruses are maintained in stable relationships with other species of animals, and their emergence within the human population results from cross-species transmission. Therefore, if we want to be prepared for the next emerging virus, we need to broadly characterize the diversity and ecology of viruses currently infecting other animals (i.e., the animal virosphere). High-throughput metagenomic sequencing has accelerated the pace of virus discovery. However, molecular assays can detect only active infections and only if virus is present within the sampled fluid or tissue at the time of collection. In contrast, serological assays measure long-lived antibody responses to infections, which can be detected within the blood, regardless of the infected tissues. Therefore, serological assays can provide a complementary approach for understanding the circulation of viruses, and while serological assays have historically been limited in scope, recent advancements allow thousands to hundreds of thousands of antigens to be assessed simultaneously using <1 μL of blood (i.e., highly multiplexed serology). The application of highly multiplexed serology for the characterization of the animal virosphere is dependent on the availability of reagents that can be used to capture or label antibodies of interest. Here, we evaluate the utility of commercial immunoglobulin-binding proteins (protein A and protein G) to enable highly multiplexed serology in 25 species of nonhuman mammals, and we describe a competitive fluorescence-linked immunosorbent assay (FLISA) that can be used as an initial screen for choosing the most appropriate capture protein for a given host species. IMPORTANCE Antibodies are generated in response to infections with viruses and other pathogens, and they help protect against future exposures. Mature antibodies are long lived, are highly specific, and can bind to their protein targets with high affinity. Thus, antibodies can also provide information about an individual's history of viral exposures, which has important applications for understanding the epidemiology and etiology of disease. In recent years, there have been large advances in the available methods for broadly characterizing antibody-binding profiles, but thus far, these have been utilized primarily with human samples only. Here, we demonstrate that commercial antibody-binding reagents can facilitate modern antibody assays for a wide variety of mammalian species, and we describe an inexpensive and fast approach for choosing the best reagent for each animal species. By studying antibody-binding profiles in captive and wild animals, we can better understand the distribution and prevalence of viruses that could spill over into humans.

Detection and Characterization of a Reassortant Mammalian Orthoreovirus Isolated from Bats in Xinjiang, China

Mammalian orthoreoviruses (MRVs) are increasingly reported to cause various diseases in humans and other animals, with many possibly originating from bats, highlighting the urgent need to investigate the diversity of bat-borne MRVs (BtMRVs). Here, we report the detection and characterization of a reassortant MRV that was isolated from a bat colony in Xinjiang, China. The BtMRV showed a wide host and organ tropism and can efficiently propagate the cell lines of different animals. It caused mild damage in the lungs of the experimentally inoculated suckling mice and was able to replicate in multiple organs for up to three weeks post-inoculation. Complete genome analyses showed that the virus was closely related to MRVs in a wide range of animals. An intricate reassortment network was revealed between the BtMRV and MRVs of human, deer, cattle, civet and other bat species. Specifically, we found a bat-specific clade of segment M1 that provides a gene source for the reassortment of human MRVs. These data provide important insights to understand the diversity of MRVs and their natural circulation between bats, humans, and other animals. Further investigation and surveillance of MRV in bats and other animals are needed to control and prevent potential MRV-related diseases.

Isolation and characterization of an orthoreovirus from Indonesian fruit bats

Nelson Bay orthoreovirus (NBV) is an emerging bat-borne virus and causes respiratory tract infections in humans sporadically. Over the last two decades, several strains genetically related to NBV were isolated from humans and various bat species, predominantly in Southeast Asia (SEA), suggesting a high prevalence of the NBV species in this region. In this study, an orthoreovirus (ORV) belonging to the NBV species was isolated from Indonesian fruit bats' feces, tentatively named Paguyaman orthoreovirus (PgORV). Serological studies revealed that 81.2% (108/133) of Indonesian fruit bats sera had neutralizing antibodies against PgORV. Whole-genome sequencing and phylogenetic analysis of PgORV suggested the occurrence of past reassortments with other NBV strains isolated in SEA, indicating the dispersal and circulation of NBV species among bats in this region. Intranasal PgORV inoculation of laboratory mice caused severe pneumonia. Our study characterized PgORV's unique genetic background and highlighted the potential risk of PgORV-related diseases in Indonesia.

Trafficked Malayan pangolins contain viral pathogens of humans

Pangolins are the most trafficked wild animal in the world according to the World Wildlife Fund. The discovery of SARS-CoV-2-related coronaviruses in Malayan pangolins has piqued interest in the viromes of these wild, scaly-skinned mammals. We sequenced the viromes of 161 pangolins that were smuggled into China and assembled 28 vertebrate-associated viruses, 21 of which have not been previously reported in vertebrates. We named 16 members of Hunnivirus, Pestivirus and Copiparvovirus pangolin-associated viruses. We report that the l-protein has been lost from all hunniviruses identified in pangolins. Sequences of four human-associated viruses were detected in pangolin viromes, including respiratory syncytial virus, Orthopneumovirus, RotavirusA and Mammalian orthoreovirus. The genomic sequences of five mammal-associated and three tick-associated viruses were also present. Notably, a coronavirus related to HKU4-CoV, which was originally found in bats, was identified. The presence of these viruses in smuggled pangolins identifies these mammals as a potential source of emergent pathogenic viruses.

Multiple pathogenic viruses are identified in a large set of pangolins, which shows that trading pangolins for scales or flesh may increase the risk of emergence of viral infections.

[Dwarf bat's (Pipistrellus pipistrellus) lung diploid cell strains and their permissivity to orbiviruses (Reoviridae: Orbivirus) - pathogens of vector-borne animal diseases]

INTRODUCTION

Bat cell cultures are a popular model both for the isolation of vector-borne disease viruses and for assessing the possible role of these mammalian species in forming the natural reservoirs of arbovirus infection vectors. The goal of the research was to obtain and characterize strains of diploid lung cells of the bat (Pipistrellus pipistrellus) and evaluate their permissivity to bluetongue, African horse sickness (AHS), and epizootic hemorrhagic disease of deer (EHD) viruses.

MATERIALS AND METHODS

Cell cultures of the dwarf bat's lung were obtained by standard enzymatic disaggregation of donor tissue and selection of cells for adhesive properties. The permissivity of cell cultures was determined to bluetongue, AHL, and EHD orbiviruses.

RESULTS

Diploid cell strains (epithelium-like and fibroblast-like types) retaining cytomorphological characteristics and karyotype stability were obtained from tissue of the bat's lung. Their permissivity to viruses of the genus Orbivirus of the Reoviridae family, pathogens of transmissible animal diseases, has been established.

DISCUSSION

The permissivity of the obtained strains of bat's lung cells to bluetongue, AHL, and EHD viruses is consistent with the isolation of orbiviruses in bats of the species Pteropus poliocephalus, Pteropus hypomelanus, Rousettus aegyptiacus leachii, Syconycteris crassa, Myotis macrodactylus, and Eidolon helvum.

CONCLUSION

Strains of diploid lung cells of the dwarf bat are permissive to orbiviruses of bluetongue, AHS, and EHD, which allows us to recommend them for the isolation of these viruses, and the species Pipistrellus pipistrellus to be considered as a potential natural reservoir and carrier of pathogens of these vector-borne diseases.

Characterization of replication and variations in genome segments of a bat reovirus, BatMRV/B19-02, by RNA-seq in infected Vero-E6 cells

Mammalian orthoreoviruses (MEVs) that can cause enteric, respiratory, and encephalitic infections have been identified in a wide variety of mammalian species. Here, we report a novel MRV type 1 strain detected in Miniopterus schreibersii that may have resulted from reassortment events. Using next-generation RNA sequencing (RNA-seq), we found that the ratios of the RNA levels of the 10 reovirus segments in infected cells were constant during the late stages of infection. We also discovered that the relative abundance of each segment differed. Notably, the relative abundance of M2 (encoding the µ1 protein) and S4 (encoding the σ3 protein) RNAs was higher than that of the others throughout the infection. Additionally, massive junctions were identified. These results support the hypothesis that defective genome segments are generated and that cross-family recombination occurs. These data may further the study of gene function, viral replication, and virus evolution.

Update on Potentially Zoonotic Viruses of European Bats

Bats have been increasingly gaining attention as potential reservoir hosts of some of the most virulent viruses known. Numerous review articles summarize bats as potential reservoir hosts of human-pathogenic zoonotic viruses. For European bats, just one review article is available that we published in 2014. The present review provides an update on the earlier article and summarizes the most important viruses found in European bats and their possible implications for Public Health. We identify the research gaps and recommend monitoring of these viruses.

Metagenomic analysis of fecal and tissue samples from 18 endemic bat species in Switzerland revealed a diverse virus composition including potentially zoonotic viruses

Many recent disease outbreaks in humans had a zoonotic virus etiology. Bats in particular have been recognized as reservoirs to a large variety of viruses with the potential to cross-species transmission. In order to assess the risk of bats in Switzerland for such transmissions, we determined the virome of tissue and fecal samples of 14 native and 4 migrating bat species. In total, sequences belonging to 39 different virus families, 16 of which are known to infect vertebrates, were detected. Contigs of coronaviruses, adenoviruses, hepeviruses, rotaviruses A and H, and parvoviruses with potential zoonotic risk were characterized in more detail. Most interestingly, in a ground stool sample of a Vespertilio murinus colony an almost complete genome of a Middle East respiratory syndrome-related coronavirus (MERS-CoV) was detected by Next generation sequencing and confirmed by PCR. In conclusion, bats in Switzerland naturally harbour many different viruses. Metagenomic analyses of non-invasive samples like ground stool may support effective surveillance and early detection of viral zoonoses.

Isolation and characterization of novel reassortant mammalian orthoreovirus from pigs in the United States

Mammalian orthoreovirus (MRV) infects multiple mammalian species including humans. A United States Midwest swine farm with approximately one thousand 3-month-old pigs experienced an event, in which more than 300 pigs showed neurological signs, like "down and peddling", with approximately 40% mortality. A novel MRV was isolated from the diseased pigs. Sequence and phylogenetic analysis revealed that the isolate was a reassortant virus containing viral gene segments from three MRV serotypes that infect human, bovine and swine. The M2 and S1 segment of the isolate showed 94% and 92% nucleotide similarity to the M2 of the MRV2 D5/Jones and the S1 of the MRV1 C/bovine/Indiana/MRV00304/2014, respectively; the remaining eight segments displayed 93%-95% nucleotide similarity to those of the MRV3 FS-03/Porcine/USA/2014. Pig studies showed that both MRV-infected and native contact pigs displayed fever, diarrhoea and nasal discharge. MRV RNA was detected in different intestinal locations of both infected and contact pigs, indicating that the MRV isolate is pathogenic and transmissible in pigs. Seroconversion was also observed in experimentally infected pigs. A prevalence study on more than 180 swine serum samples collected from two states without disease revealed 40%-52% positive to MRV. All results warrant the necessity to monitor MRV epidemiology and reassortment as the MRV could be an important pathogen for the swine industry and a novel MRV might emerge to threaten animal and public health.

Isolation and characterization of mammalian orthoreovirus type 3 from a fecal sample from a wild boar in Japan

Mammalian orthoreoviruses (MRVs) have been identified in various mammalian species, including humans, bats, and pigs. However, isolation and complete genome sequences of MRVs from wild boars have not yet been reported. In this study, we isolated, sequenced, and analyzed an MRV from a free-living wild boar in Japan using the porcine-sapelovirus-resistant cell line N1380. Complete and empty virus particles were obtained from the N1380 cell culture supernatants, and complete genome sequences were obtained from complete virus particles. Sequence analysis revealed that the isolated MRV, named TY-14, could be classified as MRV3 and had a close genetic relationship to an MRV2 isolate from a lion in a Japanese zoo (L2, L3, and M3 genes) and a human MRV2 isolate from Japan (S2 gene). Phylogenetic analysis showed that TY-14 clustered only with bat MRVs in the M1 phylogenetic tree but formed a cluster with several animal MRVs in the M2 and S3 phylogenetic trees and branched independently in the L1, S1, and S4 phylogenetic trees, suggesting a genetic relationship to viruses of unknown origin. Recombination events were identified in the M2 gene. These results suggest that TY-14 was generated by reassortment and recombination events involving MRVs circulating in Japan, viruses from bats, and other viruses of unknown origin.

The virome of German bats: comparing virus discovery approaches

Bats are known to be reservoirs of several highly pathogenic viruses. Hence, the interest in bat virus discovery has been increasing rapidly over the last decade. So far, most studies have focused on a single type of virus detection method, either PCR, virus isolation or virome sequencing. Here we present a comprehensive approach in virus discovery, using all three discovery methods on samples from the same bats. By family-specific PCR screening we found sequences of paramyxoviruses, adenoviruses, herpesviruses and one coronavirus. By cell culture we isolated a novel bat adenovirus and bat orthoreovirus. Virome sequencing revealed viral sequences of ten different virus families and orders: three bat nairoviruses, three phenuiviruses, one orbivirus, one rotavirus, one orthoreovirus, one mononegavirus, five parvoviruses, seven picornaviruses, three retroviruses, one totivirus and two thymoviruses were discovered. Of all viruses identified by family-specific PCR in the original samples, none was found by metagenomic sequencing. Vice versa, none of the viruses found by the metagenomic virome approach was detected by family-specific PCRs targeting the same family. The discrepancy of detected viruses by different detection approaches suggests that a combined approach using different detection methods is necessary for virus discovery studies.

[Biological characteristics and permissiveness to viruses of diploid kidney cells strain from the bat Nathusius' pipistrelle (Pipistrellus nathusii Keyserling & Blasius, 1839; Chiroptera: Microchiroptera: Vespertilionidae)]

INTRODUCTION

Bats are an epidemiologically important natural reservoir of viruses of various taxonomic groups, including causative agents of especially dangerous infections of humans and animals. Considering the relevance of arbovirus infections, it seems advisable to study the spectrum of the sensitivity of cells derived from bats inhabiting and migrating on the territory of the Russian Federation to causative agents of vector-borne diseases of animals.The study aimed to obtain a diploid strain of cells from renal tissue of bats Pipistrellus nathusii and to investigate its biological characteristics, as well as to assess its permissiveness for bluetongue (BTV); Rift Valley fever (RVFV); lumpy skin disease (LSDV); rabbit myxoma (Myxomatosis cuniculi); rabbit, or Shope fibroma (RFV); African horse sickness (AHSV) and African swine fever (ASFV) viruses.

MATERIAL AND METHODS

There were 2 clinically healthy male individuals of P. nathusii who taken as donors of organs. To obtain diploid kidney cell culture strain and to study its properties, the level of the 6th passage was investigated by conventional cytological, virological, and molecular methods. The permissiveness of the obtained cell culture for BTV, RVFV, LSDV, Myxomatosis cuniculi, RFV, AHSV and ASFV was determined.

RESULTS

The formation of a confluent monolayer was observed after 72 hours, while the proliferation index was 2.7-3.3. The cell monolayer had been maintained without changing the medium for 45 days (observation period). The stability of the karyotype had been demonstrated in continuous subculturing at the 36th passage. The cell culture named «Diploid cell line Pipistrellus nathusii kidney», and its permissiveness to BTV, RVFV, LSDV and Myxomatosis cuniculi had been demonstrated.

DISCUSSION

The sensitivity of the strain to BTV and RVFV is consistent with the data on the identification of reovirus and RVFV in Egyptian fruit bats (Rousettus aegyptiacus), and its permissiveness for LSDV and rabbits myxoma virus is consistent with the results of detection of poxviruses in big brown bat (Eptesicus fuscus).

CONCLUSION

A diploid kidney cell strain derived from P. nathusii was obtained and certified. Its permissiveness to BTV, RVFV, LSDV and rabbits myxoma viruses makes it possible to use this strain for isolation and studies of these viruses. Reproduction of the viruses in diploid kidney cells strain derived from P. nathusii living and migrating in the European part of the Russian Federation indicates their potential role in the epidemiology of significant infections, especially transmissible ones.

Isolation and pathogenicity analysis of mink orthoreoviruses

Mammalian orthoreoviruses (MRVs) can infect many mammals including human, and numerous higher virulent MRVs have been reported in recent years. The first mink orthoreovirus was reported in China in 2011. In the present study, three new strains of mammalian orthoreoviruses were isolated from mink and found to be most closely related to human strain MRV2Tou05 and other human strains. Mink experiments demonstrated that the isolated mink reoviruses did not lead to severe pathogenicity. Viruses were eliminated within 2 weeks after infection, but they may cause viral enteritis disease in puppies.

Mammalian Orthoreovirus (MRV) Is Widespread in Wild Ungulates of Northern Italy

Mammalian orthoreoviruses (MRVs) are emerging infectious agents that may affect wild animals. MRVs are usually associated with asymptomatic or mild respiratory and enteric infections. However, severe clinical manifestations have been occasionally reported in human and animal hosts. An insight into their circulation is essential to minimize the risk of diffusion to farmed animals and possibly to humans. The aim of this study was to investigate the presence of likely zoonotic MRVs in wild ungulates. Liver samples were collected from wild boar, red deer, roe deer, and chamois. Samples originated from two areas (Sondrio and Parma provinces) in Northern Italy with different environmental characteristics. MRV detection was carried out by PCR; confirmation by sequencing and typing for MRV type 3, which has been frequently associated with disease in pigs, were carried out for positive samples. MRV prevalence was as high as 45.3% in wild boars and 40.6% in red deer in the Sondrio area, with lower prevalence in the Parma area (15.4% in wild boars). Our findings shed light on MRV occurrence and distribution in some wild species and posed the issue of their possible role as reservoir.

An overview of viruses discovered over the last decades and drug development for the current pandemic

Since the discovery of the yellow fever virus in 1901, thus far, two hundred nineteen viral species are recognized as human pathogens. Each year, the number of viruses causing infections in humans increases, triggering epidemics and pandemics, such as the current COVID-19 pandemic. Pointing to bats as the natural host, in 2019, a genome highly identical to a bat coronavirus (COVID-19) spread all over the world, and the World Health Organization (WHO) officially confirmed it as a pandemic. The virus mainly spreads through the respiratory tract, uses angiotensin-converting enzyme 2 (ACE2) as a receptor, and is characterized by symptoms of fever, cough, and fatigue. Antivirals and vaccines have provided improvements in some cases, but the discovery of a new and diverse variety of viruses with outbreaks has posed a challenge in timely treatments for medical scientists. Currently, few specific antiviral strategies are being used, and many of the effective antiviral drugs and reported active molecules are under vital exploration. In this review, with the details of viral diseases, we summarize the current attempts in drug development, epidemiology, and the latest treatments and scientific advancements to combat the COVID-19 epidemic. Moreover, we discuss ways to reduce epidemics and pandemics in the near future.

Interface between Bats and Pigs in Heavy Pig Production

Bats are often claimed to be a major source for future viral epidemics, as they are associated with several viruses with zoonotic potential. Here we describe the presence and biodiversity of bats associated with intensive pig farms devoted to the production of heavy pigs in northern Italy. Since chiropters or signs of their presence were not found within animal shelters in our study area, we suggest that fecal viruses with high environmental resistance have the highest likelihood for spillover through indirect transmission. In turn, we investigated the circulation of mammalian orthoreoviruses (MRVs), coronaviruses (CoVs) and astroviruses (AstVs) in pigs and bats sharing the same environment. Results of our preliminary study did not show any bat virus in pigs suggesting that spillover from these animals is rare. However, several AstVs, CoVs and MRVs circulated undetected in pigs. Among those, one MRV was a reassortant strain carrying viral genes likely acquired from bats. On the other hand, we found a swine AstV and a MRV strain carrying swine genes in bat guano, indicating that viral exchange at the bat–pig interface might occur more frequently from pigs to bats rather than the other way around. Considering the indoor farming system as the most common system in the European Union (EU), preventive measures should focus on biosecurity rather than displacement of bats, which are protected throughout the EU and provide critical ecosystem services for rural settings.

Ectoparasites and Pathogens of Kuhl's Pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae): Our Own and Published Data Review

Here we report the results of our own survey and literary published data on the ectoparasite fauna and pathogens of the alien bat species, the Kuhl's pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae). This bat is a host of 36 species of parasitic mites, ticks and insects (including accidental findings) and 13 species of pathogens (protozoa, bacteria, viruses). The flea Ischnopsyllus variabilis is re-corded on this host for the first time. We have found that outside of the host ancestral range, the core of the bat parasite fauna is significantly different due to the loss of host species-specific ectoparasites. Particularly, in Russia, only 6 species of parasitic arthropods have been recorded for Kuhl's pipistrelle and all of them are host genus-specific. At the same time, the features of ecology and occasional finds of extrinsic parasites allow to suggest that P. kuhlii has wide contacts with animals which are the reservoirs of zoonotic infec-tions, that in combination with the fact of isolation of several pathogens from this species (including two coronaviruses) points to a possible medical importance of Kuhl's pipistrelle.

Isolation and identification of two new strains of mammalian orthoreovirus from Chinese tree shrews

Chinese tree shrews have been used extensively in studies of different types of cancer and for the modeling of viral infections. In the present study, we report the isolation and characterization of two strains of mammalian orthoreovirus (MRV), MRV1/TS/2011 and MRV3/TS/2012, which were isolated from the feces of tree shrews in Yunnan, China. These two strains of MRV were isolated and cultured in both primary tree shrew intestinal epithelial cells (pTIECs) and primary tree shrew alveolar epithelial cells (pTAECs). A neutralization test using immunofluorescence was employed to determine the subtype of each isolate. Viral RNA was extracted and analyzed by polyacrylamide gel electrophoresis (PAGE), and the sequence was determined by next-generation sequencing for construction of a phylogenetic tree and analysis of gene polymorphism. Electron microscopy examination revealed the presence of virus particles with the typical morphological characteristics of MRV. Serotype analysis showed that strain MRV1/TS/2011 was of type I and strain MRV3/TS/2012 was of type III. A sequence comparison showed that the isolates were 25.4% identical in the S1 gene.

Bat mammalian orthoreoviruses cause severe pneumonia in mice

Mammalian orthoreovirus (MRV) infections are ubiquitous in mammals. Increasing evidence suggests that some MRVs can cause severe respiratory disease and encephalitis in humans and other animals. Previously, we isolated six bat MRV strains. However, the pathogenicity of these bat viruses remains unclear. In this study, we investigated the host range and pathogenicity of 3 bat MRV strains (WIV2, 3 and 7) which represent three serotypes. Our results showed that all of them can infect cell lines from different mammalian species and displayed different replication efficiency. The BALB/c mice infected by bat MRVs showed clinical symptoms with systematic infection especially in lung and intestines. Obvious tissue damage were found in all infected lungs. One of the strains, WIV7, showed higher replication efficiency in vitro and vivo and more severe pathogenesis in mice. Our results provide new evidence showing potential pathogenicity of bat MRVs in animals and probable risk in humans.

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Bat MRVs show wide cell tropism in vivo and in vitro and have a high replication efficiency in lung and intestines.

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Mice infected by bat MRVs showed clinical illness, but without death.

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The higher replication in brain, lung damage and weak innate immune response may be responsible for severe diseases for WIV7.

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The results indicate the potential pathogenicity of bat MRV to human and animals.

Unexpected Genetic Diversity of Two Novel Swine MRVs in Italy

Mammalian Orthoreoviruses (MRV) are segmented dsRNA viruses in the family Reoviridae. MRVs infect mammals and cause asymptomatic respiratory, gastro-enteric and, rarely, encephalic infections. MRVs are divided into at least three serotypes: MRV1, MRV2 and MRV3. In Europe, swine MRV (swMRV) was first isolated in Austria in 1998 and subsequently reported more than fifteen years later in Italy. In the present study, we characterized two novel reassortant swMRVs identified in one same Italian farm over two years. The two viruses shared the same genetic backbone but showed evidence of reassortment in the S1, S4, M2 segments and were therefore classified into two serotypes: MRV3 in 2016 and MRV2 in 2018. A genetic relation to pig, bat and human MRVs and other unknown sources was identified. A considerable genetic diversity was observed in the Italian MRV3 and MRV2 compared to other available swMRVs. The S1 protein presented unique amino acid signatures in both swMRVs, with unexpected frequencies for MRV2. The remaining genes formed distinct and novel genetic groups that revealed a geographically related evolution of swMRVs in Italy. This is the first report of the complete molecular characterization of novel reassortant swMRVs in Italy and Europe, which suggests a greater genetic diversity of swMRVs never identified before.

A novel reassortant mammalian orthoreovirus with a divergent S1 genome segment identified in a traveler with diarrhea

Mammalian orthoreoviruses with reassortant genomes have recently been detected in various mammals and humans with respiratory, central nervous system, and gastrointestinal symptoms. This study describes the detection of the novel reassortant mammalian orthoreovirus SI-MRV07 in a traveler with gastroenteritis that returned from southeast Asia. The virus was initially detected with electron microscopy in stool, followed by propagation in the epithelial-like monkey kidney Marc145 cell line. Whole-genome sequencing revealed the reassortant nature of the genome segments, whereby the S1 genome segment was the most variable according to known sequences deposited in GenBank. Based on the nucleotide sequence of the S1 genome segment, the isolate clusters to serotype 2, close to the reference strain Jones T2J. The patient's serum showed the highest virus neutralization capacity toward SI-MRV07 and T2J isolates. This study provides additional insight into emerging mammalian orthoreoviruses with reassortant genomes and possible zoonotic potential, which should be carefully monitored in the future.

Bats and Viruses: Emergence of Novel Lyssaviruses and Association of Bats with Viral Zoonoses in the EU

Bats in the EU have been associated with several zoonotic viral pathogens of significance to both human and animal health. Virus discovery continues to expand the existing understating of virus classification, and the increased interest in bats globally as reservoirs or carriers of zoonotic agents has fuelled the continued detection and characterisation of new lyssaviruses and other viral zoonoses. Although the transmission of lyssaviruses from bat species to humans or terrestrial species appears rare, interest in these viruses remains, through their ability to cause the invariably fatal encephalitis—rabies. The association of bats with other viral zoonoses is also of great interest. Much of the EU is free of terrestrial rabies, but several bat species harbor lyssaviruses that remain a risk to human and animal health. Whilst the rabies virus is the main cause of rabies globally, novel related viruses continue to be discovered, predominantly in bat populations, that are of interest purely through their classification within the lyssavirus genus alongside the rabies virus. Although the rabies virus is principally transmitted from the bite of infected dogs, these related lyssaviruses are primarily transmitted to humans and terrestrial carnivores by bats. Even though reports of zoonotic viruses from bats within the EU are rare, to protect human and animal health, it is important characterise novel bat viruses for several reasons, namely: (i) to investigate the mechanisms for the maintenance, potential routes of transmission, and resulting clinical signs, if any, in their natural hosts; (ii) to investigate the ability of existing vaccines, where available, to protect against these viruses; (iii) to evaluate the potential for spill over and onward transmission of viral pathogens in novel terrestrial hosts. This review is an update on the current situation regarding zoonotic virus discovery within bats in the EU, and provides details of potential future mechanisms to control the threat from these deadly pathogens.

Identification of novel reassortant mammalian orthoreoviruses from bats in Slovenia

Background

Recently, mammalian orthoreoviruses (MRVs) were detected for the first time in European bats, and the closely related strain SI-MRV01 was isolated from a child with severe diarrhoea in Slovenia. Genetically similar strains have also been reported from other mammals, which reveals their wide host distribution. The aim of this study was to retrospectively investigate the occurrence and genetic diversity of MRVs in bats in Slovenia, from samples obtained throughout the country in 2008 to 2010, and in 2012 and to investigate the occurrence of the novel SI-MRV01 MRV variant in Slovenian bats.

Results

The detection of MRVs in bat guano was based on broad-range RT-PCR and specific bat MRV real-time RT-PCR. Subsequently, MRV isolates were obtained from cell culture propagation, with detailed molecular characterisation through whole-genome sequencing.

Overall, bat MRVs were detected in 1.9% to 3.8% of bats in 2008, 2009 and 2012. However, in 2010 the prevalence was 33.0%, which defined an outbreak of the single SI-MRV01 strain. Here, we report on the identification of five MRV isolates of different serotypes that are designated as SI-MRV02, SI-MRV03, SI-MRV04, SI-MRV05 and SI-MRV06. There is high genetic variability between these characterised isolates, with evident genome reassortment seen across their genome segments.

Conclusions

In conclusion, we have confirmed the presence of the SI-MRV01 strain in a Slovenian bat population. Moreover, according to genetic characterisation of S1 genome segment, all three MRV serotypes were present in the bat population. In this study, five independent MRV isolates were obtained and detailed whole genome analysis revealed high diversity between them. This study generates new information about the epidemiology and molecular characteristics of emerging bat MRV variants, and provides important molecular data for further studies of their pathogenesis and evolution.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1585-y) contains supplementary material, which is available to authorized users.

Persistent mammalian orthoreovirus, coxsackievirus and adenovirus co-infection in a child with a primary immunodeficiency detected by metagenomic sequencing: a case report

Background

We report a rare case of Mammalian orthoreovirus (MRV) infection in a child with a primary immunodeficiency (PID). Infections with Mammalian orthoreovirus are very rare and probably of zoonotic origin. Only a few cases have been described so far, including one with similar pathogenesis as in our case.

Case presentation

The patient, age 11, presented with flu-like symptoms and persistent severe diarrhea. Enterovirus has been detected over several months, however, exact typing of a positive cell culture remained inconclusive. Unbiased metagenomic sequencing then detected MRV in stool samples from several time points. The sequencing approach further revealed co-infection with a recombinant Coxsackievirus and Adenovirus. MRV-specific antibodies detected by immunofluorescence proved that the patient seroconverted.

Conclusion

This case highlights the potential of unbiased metagenomic sequencing in supplementing routine diagnostic methods, especially in situations of chronic infection with multiple viruses as seen here in an immunocompromised host. The origin, transmission routes and implications of MRV infection in humans merit further investigation.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-2946-7) contains supplementary material, which is available to authorized users.

A novel Coltivirus-related virus isolated from free-tailed bats from Côte d'Ivoire is able to infect human cells in vitro

BACKGROUND

Zoonotic transmission events play a major role in the emergence of novel diseases. While such events are virtually impossible to predict, wildlife screening for potential emerging pathogens can be a first step. Driven by recent disease epidemics like severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and Ebola, bats have gained special interest as reservoirs of emerging viruses.

METHODS

As part of a bigger study investigating pathogens in African bats we screened animals for the presence of known and unknown viruses.

RESULTS

We isolated and characterised a novel reovirus from blood of free-tailed bats (Chaereophon aloysiisabaudiae) captured in 2006 in Côte d'Ivoire. The virus showed closest relationship with two human pathogenic viruses, Colorado tick fever virus and Eyach virus, and was able to infect various human cell lines in vitro.

CONCLUSION

The study shows the presence of a coltivirus-related virus in bats from Sub-Sahara Africa. Serological studies could help to assess its impact on humans or wildlife health.

Genetic and pathogenic characterization of a novel reassortant mammalian orthoreovirus 3 (MRV3) from a diarrheic piglet and seroepidemiological survey of MRV3 in diarrheic pigs from east China

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A novel reassortant mammalian orthoreovirus 3 (MRV3), designated MRV-ZJ2013, was isolated from diarrheic piglets.

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Genomic and phylogenetic analysis shows that MRV-ZJ2013 may have originated from reassortments among mink, bat, and pig MRVs.

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Experimental infection study showed that MRV-ZJ2013 had low, if any, pathogenesis in newborn piglets.

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A seroepidemiological survey of MRV3 revealed a high seroprevalence (77%) from diarrheic pigs of different ages in east China.

Mammalian orthoreoviruses (MRVs), which cause gastrointestinal and respiratory illness, have been isolated from a wide variety of mammalian species including bats, minks, pigs and humans. Here we report the isolation and genetic and pathogenic characterization of a novel MRV type 3 (MRV3), named MRV-ZJ2013, from the diarrheic feces of piglets in Zhejiang province, China. Genomic and phylogenetic analysis shows that MRV-ZJ2013 may have originated from reassortments among mink, bat, and pig MRVs, suggesting the hypothesis that interspecies transmission has occurred in pig herds. Neonatal piglets infected with MRV-ZJ2013 displayed mild clinical signs such as poor appetite and soft feces, but vomiting and diarrhea were not observed. Fecal virus shedding was detected only in three out of six piglets, each for one- or two-day post-infection. In contrast, piglets inoculated with a virulent porcine epidemic diarrhea virus (PEDV) strain as the control group had severe signs characterized by acute vomiting and watery diarrhea. These findings suggest that the virulence of MRV-ZJ2013, if any, was likely not significant compared to that of PEDV. A seroepidemiological survey of MRV by means of an indirect enzyme-linked immune-sorbent assay (ELISA) based on a recombinant MRV3 capsid protein sigma1 as antigen revealed a high seroprevalence (77%) in 1037 samples from diarrheic pigs of different ages from 24 herds in seven provinces of east China between 2015 and 2016, indicating that MRV3 is endemic in pig herds in China, and may contribute collectively to enteric disease along with other porcine pathogens.

Rethinking the Significance of Reovirus in Water and Wastewater

The genus Orthoreovirus contains nonenveloped viruses with double-stranded gene segments encased in a double-layered icosahedral capsid shell. These features constitute major determinants of virion stability in the environment and virion resistance against physical and chemical agents. Reovirus (ReoV) is the general term most commonly used for all virus strains that infect humans and nonhuman animals. Several studies have demonstrated the frequent occurrence of ReoV in wastewaters and natural waters, including surface and ground waters from different geographical areas. Most of these studies have reported higher concentrations of ReoV than any other enteric virus analyzed. They are more commonly isolated in chlorine-disinfected wastewaters than other enteric viruses, and appear to survive longer in water. The ability of ReoV to form large aggregates, even with different types of enteric viruses (e.g., poliovirus) and their ability to undergo mechanisms of gene segment reassortment among different serotypes may also explain their greater stability. Different approaches have been applied for concentration of ReoV from water; however, the recovery efficiency of the filtration methods has not been fully evaluated. Recently, molecular methods for identification of ReoV strains and quantification of virus genome have been developed. Studies have shown that the overall detection sensitivity of ReoV RNA is enhanced through initial replication of infectious virions in cell culture. More studies are needed to specifically address unresolved issues about the fate and distribution of ReoV in the environment since this virus is not commonly included in virological investigations.

Bat-man disease transmission: zoonotic pathogens from wildlife reservoirs to human populations

Bats are natural reservoir hosts and sources of infection of several microorganisms, many of which cause severe human diseases. Because of contact between bats and other animals, including humans, the possibility exists for additional interspecies transmissions and resulting disease outbreaks. The purpose of this article is to supply an overview on the main pathogens isolated from bats that have the potential to cause disease in humans.

Isolation and identification of bat viruses closely related to human, porcine and mink orthoreoviruses

Bats have been identified as natural reservoirs of many viruses, including reoviruses. Recent studies have demonstrated the interspecies transmission of bat reoviruses to humans. In this study, we report the isolation and molecular characterization of six strains of mammalian orthoreovirus (MRV) from Hipposideros and Myotis spp. These isolates were grouped into MRV serotype 1, 2 or 3 based on the sequences of the S1 gene, which encodes the outer coat protein s1. Importantly, we found that three of six bat MRV strains shared high similarity with MRVs isolated from diseased minks, piglets or humans based on the S1 segment, suggesting that interspecies transmission has occurred between bats and humans or animals. Phylogenetic analyses based on the 10 segments showed that the genomic segments of these bat MRVs had different evolution lineages, suggesting that these bat MRVs may have arisen through reassortment of MRVs of different origins.

Characterization and pathogenicity of a novel mammalian orthoreovirus from wild short-nosed fruit bats

Mammalian orthoreoviruses (MRVs) have a wide range of geographic distribution and have been isolated from humans and various animals. This study describes the isolation, molecular characterization and analysis of pathogenicity of MRV variant B/03 from wild short-nosed fruit bats. Negative stain electron microscopy illustrated that the B/03 strain is a non-enveloped icosahedral virus with a diameter of 70nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) migration patterns showed that the B/03 viral genome contains 10 segments in a 3:3:4 arrangement. The isolate belongs to MRV serotype 1 based on S1 gene nucleotide sequence data. BALB/c mice experimentally infected with B/03 virus by intranasal inoculation developed severe respiratory distress with tissue damage and inflammation. Lastly, B/03 virus has an increased transmission risk between bats and humans or animals.

Serologic assays for the detection and strain identification of Pteropine orthoreovirus

Pteropine orthoreovirus (PRV), potentially of bat origin, is reported to be a causative agent of emerging respiratory tract infections among humans in Southeast Asia. We evaluated the efficacy of serologic assays using the major outer capsid and cell attachment proteins (CAP) of PRV strains in the screening, confirmation and identification of three groups of human PRV infections; Indonesian/Japanese, Indonesian/Hong Kong and Malaysian strains. The different serologic assays were tested using rabbit polyclonal antisera raised against these proteins of selected PRV strains, and validation was carried out using sera from a Miyazaki-Bali/2007 PRV-infected patient and the patient's contacts. The results of this study showed that rabbit polyclonal antisera raised against the CAP of the Miyazaki-Bali/2007 PRV strain showed the highest reactivity to the Miyazaki-Bali/2007 PRV and to a lesser extent, cross-reactivity with the HK23629/07 and Melaka PRVs, respectively. Neutralization activity against the Miyazaki-Bali/2007 PRV was observed using rabbit anti-Miyazaki-Bali/2007 PRV CAP (320) but not with rabbit anti-HK23629/07 (<20) and Melaka (<20) PRV CAP. This lack of cross-neutralization, suggests the potential for human reinfection with different strains. The use of sera collected from contacts of the Miyazaki-Bali/2007 PRV-infected patient suggested that human-to-human infections with PRV are unlikely. Previously reported cases of PRV infections among human have been mild. However, the expanding geographic distribution of these viruses, of which its virulence remains unknown, warrants close monitoring to enable the development of prevention and control strategies in the event that a change in virulence occurs.

Isolation of a Novel Fusogenic Orthoreovirus from Eucampsipoda africana Bat Flies in South Africa

We report on the isolation of a novel fusogenic orthoreovirus from bat flies (Eucampsipoda africana) associated with Egyptian fruit bats (Rousettus aegyptiacus) collected in South Africa. Complete sequences of the ten dsRNA genome segments of the virus, tentatively named Mahlapitsi virus (MAHLV), were determined. Phylogenetic analysis places this virus into a distinct clade with Baboon orthoreovirus, Bush viper reovirus and the bat-associated Broome virus. All genome segments of MAHLV contain a 5' terminal sequence (5'-GGUCA) that is unique to all currently described viruses of the genus. The smallest genome segment is bicistronic encoding for a 14 kDa protein similar to p14 membrane fusion protein of Bush viper reovirus and an 18 kDa protein similar to p16 non-structural protein of Baboon orthoreovirus. This is the first report on isolation of an orthoreovirus from an arthropod host associated with bats, and phylogenetic and sequence data suggests that MAHLV constitutes a new species within the Orthoreovirus genus.

Optimizing Viral Discovery in Bats

Viral discovery studies in bats have increased dramatically over the past decade, yet a rigorous synthesis of the published data is lacking. We extract and analyze data from 93 studies published between 2007-2013 to examine factors that increase success of viral discovery in bats, and specific trends and patterns of infection across host taxa and viral families. Over the study period, 248 novel viruses from 24 viral families have been described. Using generalized linear models, at a study level we show the number of host species and viral families tested best explained number of viruses detected. We demonstrate that prevalence varies significantly across viral family, specimen type, and host taxonomy, and calculate mean PCR prevalence by viral family and specimen type across all studies. Using a logistic model, we additionally identify factors most likely to increase viral detection at an individual level for the entire dataset and by viral families with sufficient sample sizes. Our analysis highlights major taxonomic gaps in recent bat viral discovery efforts and identifies ways to improve future viral pathogen detection through the design of more efficient and targeted sample collection and screening approaches.

Novel antiviral effect of lithium chloride on mammalian orthoreoviruses in vitro

Reovirus not only causes considerable economic loss in the swine industry of the United States and other countries, but also threatens the public health due to its zoonotic potential. According to previous reports, LiCl has antiviral activity against a number of viruses. The inhibitory effects of LiCl on reovirus life cycle in Vero cells were evaluated. The unpaired t-test and one-way ANOVA were used to analyze the differences between experimental groups. We first found that LiCl treatment significantly inhibited reovirus replication in a dose-dependent manner. Furthermore, we found that this antiviral activity of LiCl targets the early stage of viral replication. LiCl could be a potential drug against reovirus infection.

Insectivorous bats carry host specific astroviruses and coronaviruses across different regions in Germany

Recently several infectious agents with a zoonotic potential have been detected in different bat species. However, there is still a lack of knowledge on the transmission dynamics within and between bat species, as well as from bats to other mammals. To better understand these processes, it is important to compare the phylogenetic relationships between different agents to that of their respective hosts. In this study, we analysed more than 950 urine, faeces and oral swab samples collected from 653 bats from mainly four species (Myotis nattereri, Myotis bechsteinii, Myotis daubentonii, and Plecotus auritus) for the presence of coronavirus, paramyxovirus and astrovirus related nucleic acids located in three different regions of Germany. Using hemi-nested reverse transcriptase (RT)-PCR amplification of fragments within the highly conserved regions of the respective RNA dependent RNA polymerase (RdRp) genes, we detected astrovirus sequences at an overall detection rate of 25.8% of the analysed animals, with a maximum of 65% in local populations. The detection rates for coronaviruses and paramyxoviruses were distinctly lower, ranging between 1.4% and 3.1%. Interestingly, the sequence similarities in samples collected from the same bat species in different geographical areas were distinctly larger than the sequence similarities between samples from different species sampled at the same location. This indicates that host specificity may be more important than host ecology for the presence of certain viruses in bats.

Rapid whole genome sequencing of Miyazaki-Bali/2007 Pteropine orthoreovirus by modified rolling circular amplification with adaptor ligation - next generation sequencing

The emergence of orthoreoviruses as the causative agent of human respiratory illness over the past few years has led to a demand to determine their viral genome sequences. The whole genome sequencing of such RNA viruses using traditional methods, such as Sanger dideoxy sequencing following rapid amplification of cDNA ends presents a laborious challenge due to the numerous preparatory steps required before sequencing can commence. We developed a practical, time-efficient novel combination method capable of reducing the total time required from months to less than a week in the determination of whole genome sequence of Pteropine orthoreoviruses (PRV); through a combination of viral RNA purification and enrichment, adaptor ligation, reverse transcription, cDNA circularization and amplification, and next generation sequencing. We propose to call the method "modified rolling circular amplification with adaptor ligation - next generation sequencing (mRCA-NGS)". Here, we describe the technological focus and advantage of mRCA-NGS and its expansive application, exemplified through the phylogenetic understanding of the Miyazaki-Bali/2007 PRV.

Detection and Characterization of a Novel Reassortant Mammalian Orthoreovirus in Bats in Europe

A renewed interest in mammalian orthoreoviruses (MRVs) has emerged since new viruses related to bat MRV type 3, detected in Europe, were identified in humans and pigs with gastroenteritis. This study reports the isolation and characterization of a novel reassortant MRV from the lesser horseshoe bat (Rhinolophus hipposideros). The isolate, here designated BatMRV1-IT2011, was first identified by electron microscopy and confirmed using PCR and virus-neutralization tests. The full genome sequence was obtained by next-generation sequencing. Molecular and antigenic characterizations revealed that BatMRV1-IT2011 belonged to serotype 1, which had not previously been identified in bats. Phylogenetic and recombination detection program analyses suggested that BatMRV1-IT2011 was a reassortant strain containing an S1 genome segment similar to those of MRV T1/bovine/Maryland/Clone23/59 and C/bovine/Indiana/MRV00304/2014, while other segments were more similar to MRVs of different hosts, origins and serotypes. The presence of neutralizing antibodies against MRVs has also been investigated in animals (dogs, pigs, bovines and horses). Preliminary results suggested that MRVs are widespread in animals and that infections containing multiple serotypes, including MRVs of serotype 1 with an S1 gene similar to BatMRV1-IT2011, are common. This paper extends the current knowledge of MRVs and stresses the importance to continue and improve MRV surveillance in bats and other mammals through the development and standardization of specific diagnostic tools.

Isolation and pathogenicity of the mammalian orthoreovirus MPC/04 from masked civet cats

Mammalian reoviruses (MRVs) are associated with pulmonary infections and have been isolated from humans and various animals experiencing respiratory illness. We report here the first case of an MRV detected in the masked palm civet, which showed the highest similarity to the serotype 3 MRV. Reovirus particles were identified by electron microscopic examination of both negative-stain and thin-section. Genomic pattern analysis on SDS-PAGE showed that MPC/04 had 10-segmented double-strand RNA genome. Intranasal infection of four-week-old female BALB/c mice resulted in fatal respiratory distress but not other routes. Infections caused tissue damage and inflammation. MPC/04 grew to higher titers in the lungs than in other tissues. This research strongly suggests a need for additional experimentation to understand the pathogenic mechanisms of mammalian orthoreoviruses in infected animals and humans.

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An MRV strain was isolated from masked palm civet cats in China.

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Phylogenetic analysis indicates that MPC/04 is the product of reassortment strains.

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Pathogenesis studies suggest a propensity for infection via the respiratory route.

Protocol for metagenomic virus detection in clinical specimens

This protocol can rapidly and reliably detect viruses during disease outbreaks and for detection studies.

Sixty percent of emerging viruses have a zoonotic origin, making transmission from animals a major threat to public health. Prompt identification and analysis of these pathogens are indispensable to taking action toward prevention and protection of the affected population. We quantifiably compared classical and modern approaches of virus purification and enrichment in theory and experiments. Eventually, we established an unbiased protocol for detection of known and novel emerging viruses from organ tissues (tissue-based universal virus detection for viral metagenomics [TUViD-VM]). The final TUViD-VM protocol was extensively validated by using real-time PCR and next-generation sequencing. We could increase the amount of detectable virus nucleic acids and improved the detection of viruses <75,000-fold compared with other tested approaches. This TUViD-VM protocol can be used in metagenomic and virome studies to increase the likelihood of detecting viruses from any biological source.

Molecular survey of RNA viruses in Hungarian bats: discovering novel astroviruses, coronaviruses, and caliciviruses

Background: Bat-borne viruses pose a potential risk to human health and are the focus of increasing scientific interest. To start gaining information about bat-transmitted viruses in Hungary, we tested multiple bat species for several virus groups between 2012 and 2013.

MATERIALS AND METHODS

Fecal samples were collected from bats across Hungary. We performed group-specific RT-PCR screening for astro-, calici-, corona-, lyssa-, othoreo-, paramyxo-, and rotaviruses. Positive samples were selected and sequenced for further phylogenetic analyses.

RESULTS

A total of 447 fecal samples, representing 24 European bat species were tested. Novel strains of astroviruses, coronaviruses, and caliciviruses were detected and analyzed phylogenetically. Out of the 447 tested samples, 40 (9%) bats were positive for at least one virus. Bat-transmitted astroviruses (BtAstV) were detected in eight species with a 6.93% detection rate (95% confidence interval [CI] 4.854, 9.571). Coronaviruses (BtCoV) were detected in seven bat species with a detection rate of 1.79% (95% CI 0.849, 3.348), whereas novel caliciviruses (BtCalV) were detected in three bat species with a detection rate of 0.67% (95% CI 0.189, 1.780). Phylogenetic analyses revealed a great diversity among astrovirus strains, whereas the Hungarian BtCoV strains clustered together with both alpha- and betacoronavirus strains from other European countries. One of the most intriguing findings of our investigation is the discovery of novel BtCalVs in Europe. The Hungarian BtCalV did not cluster with any of the calcivirus genera identified in the family so far.

CONCLUSIONS

We have successfully confirmed BtCoVs in numerous bat species. Furthermore, we have described new bat species harboring BtAstVs in Europe and found new species of CalVs. Further long-term investigations involving more species are needed in the Central European region for a better understanding on the host specificity, seasonality, phylogenetic relationships, and the possible zoonotic potential of these newly described viruses.