Evolution and diversity of bat and rodent Paramyxoviruses from North America

Cleavage of the syncytial protein of J paramyxovirus is required for its ability to promote cell-cell fusion

Cell-cell fusion mediated by most paramyxovirus requires fusion protein (F) and attachment protein (H, HN, or G). The F protein is proteolytic cleaved to be fusogenically active. J paramyxovirus (JPV) has a unique feature in the family Paramyxoviridae: It encodes an integral membrane protein, syncytial protein (SP, formerly known as transmembrane protein, TM), which is essential in JPV-promoted cell-cell fusion (i.e., syncytial). In this study, we report that cleavage of SP is essential for its syncytial-promoting activity. We have identified the cleavage site of SP at amino acid residues 172 to 175, LKTG, and deletion of the "LKTG" residues abolished SP protein cleavage and its ability to promote cell-cell fusion. Replacing the cleavage site LKTG with a factor Xa protease cleavage site allows cleavage of the SP with factor Xa protease and restores its ability to promote cell-cell fusion. Furthermore, results from a hemifusion assay indicate that cleavage of SP plays an important role in the progression from the intermediate hemifusion state to a complete fusion. This work indicates that SP has many characteristics of a fusion protein. We propose that SP is likely a cell-cell fusion-promoting protein.

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

Discovery and genetic characterization of novel paramyxoviruses from small mammals in Hubei Province, Central China

Paramyxoviruses are a group of single-stranded, negative-sense RNA viruses, some of which are responsible for acute human disease, including parainfluenza virus, measles virus, Nipah virus and Hendra virus. In recent years, a large number of novel paramyxoviruses, particularly members of the genus Jeilongvirus, have been discovered in wild mammals, suggesting that the diversity of paramyxoviruses may be underestimated. Here we used hemi-nested reverse transcription PCR to obtain 190 paramyxovirus sequences from 969 small mammals in Hubei Province, Central China. These newly identified paramyxoviruses were classified into four clades: genera Jeilongvirus, Morbillivirus, Henipavirus and Narmovirus, with most of them belonging to the genus Jeilongvirus. Using Illumina sequencing and Sanger sequencing, we successfully recovered six near-full-length genomes with different genomic organizations, revealing the more complex genome content of paramyxoviruses. Co-divergence analysis of jeilongviruses and their known hosts indicates that host-switching occurred more frequently in the evolutionary histories of the genus Jeilongvirus. Together, our findings demonstrate the high prevalence of paramyxoviruses in small mammals, especially jeilongviruses, and highlight the diversity of paramyxoviruses and their genome content, as well as the evolution of jeilongviruses.

Tetracistronic Minigenomes Elucidate a Functional Promoter for Ghana Virus and Unveils Cedar Virus Replicase Promiscuity for all Henipaviruses

Batborne henipaviruses, such as Nipah virus and Hendra virus, represent a major threat to global health due to their propensity for spillover, severe pathogenicity, and high mortality rate in human hosts. Coupled with the absence of approved vaccines or therapeutics, work with the prototypical species and uncharacterized, emergent species is restricted to high biocontainment facilities. There is a scarcity of such specialized spaces for research, and often the scope and capacity of research which can be conducted at BSL-4 is limited. Therefore, there is a pressing need for innovative life-cycle modeling systems to enable comprehensive research within lower biocontainment settings. This work showcases tetracistronic, transcription and replication competent minigenomes for Nipah virus, Hendra virus, Cedar virus, and Ghana virus, which encode viral proteins facilitating budding, fusion, and receptor binding. We validate the functionality of all encoded viral proteins and demonstrate a variety of applications to interrogate the viral life cycle. Notably, we found that the Cedar virus replicase exhibits remarkable promiscuity, efficiently rescuing minigenomes from all tested henipaviruses. We also apply this technology to GhV, an emergent species which has so far not been isolated in culture. We demonstrate that the reported sequence of GhV is incomplete, but that this missing sequence can be substituted with analogous sequences from other henipaviruses. Use of our GhV system establishes the functionality of the GhV replicase and identifies two antivirals which are highly efficacious against the GhV polymerase.

Tailam paramyxovirus C protein inhibits viral replication

Jeilongviruses are emerging single-stranded negative-sense RNA viruses in the Paramyxoviridae family. Tailam paramyxovirus (TlmPV) is a Jeilongvirus that was identified in 2011. Very little is known about the mechanisms that regulate viral replication in these newly emerging viruses. Among the non-structural viral proteins of TlmPV, the C protein is predicted to be translated from an open reading frame within the phosphoprotein gene through alternative translation initiation. Though the regulatory roles of C proteins in virus replication of other paramyxoviruses have been reported before, the function of the TlmPV C protein and the relevant molecular mechanisms have not been reported. Here, we show that the C protein is expressed in TlmPV-infected cells and negatively modulates viral RNA replication. The TlmPV C protein interacts with the P protein, negatively impacting the interaction between N and P, resulting in inhibition of viral RNA replication. Deletion mutagenesis studies indicate that the 50 amino-terminal amino acid residues of the C protein are dispensable for its inhibition of virus RNA replication and interaction with the P protein.IMPORTANCETailam paramyxovirus (TlmPV) is a newly identified paramyxovirus belonging to the Jeilongvirus genus, of which little is known. In this work, we confirmed the expression of the C protein in TlmPV-infected cells, assessed its function, and defined a potential mechanism of action. This is the first time that the existence of a Jeilongvirus C protein has been confirmed and its role in viral replication has been reported.

Corona- and Paramyxoviruses in Bats from Brazil: A Matter of Concern?

Chiroptera are one of the most diverse mammal orders. They are considered reservoirs of main human pathogens, where coronaviruses (CoVs) and paramyxoviruses (PMVs) may be highlighted. Moreover, the growing number of publications on CoVs and PMVs in wildlife reinforces the scientific community's interest in eco-vigilance, especially because of the emergence of important human pathogens such as the SARS-CoV-2 and Nipha viruses. Considering that Brazil presents continental dimensions, is biologically rich containing one of the most diverse continental biotas and presents a rich biodiversity of animals classified in the order Chiroptera, the mapping of CoV and PMV genetics related to human pathogens is important and the aim of the present work. CoVs can be classified into four genera: Alphacoronavirus, Betacoronavirus, Deltacoronavirus and Gammacoronavirus. Delta- and gammacoronaviruses infect mainly birds, while alpha- and betacoronaviruses contain important animal and human pathogens. Almost 60% of alpha- and betacoronaviruses are related to bats, which are considered natural hosts of these viral genera members. The studies on CoV presence in bats from Brazil have mainly assayed phyllostomid, molossid and vespertilionid bats in the South, Southeast and North territories. Despite Brazil not hosting rhinophilid or pteropodid bats, which are natural reservoirs of SARS-related CoVs and henipaviruses, respectively, CoVs and PMVs reported in Brazilian bats are genetically closely related to some human pathogens. Most works performed with Brazilian bats reported alpha-CoVs that were closely related to other bat-CoVs, despite a few reports of beta-CoVs grouped in the Merbecovirus and Embecovirus subgenera. The family Paramyxoviridae includes four subfamilies (Avulavirinae, Metaparamyxovirinae, Orthoparamyxovirinae and Rubulavirinae), and bats are significant drivers of PMV cross-species viral transmission. Additionally, the studies that have evaluated PMV presence in Brazilian bats have mainly found sequences classified in the Jeilongvirus and Morbillivirus genera that belong to the Orthoparamyxovirinae subfamily. Despite the increasing amount of research on Brazilian bats, studies analyzing these samples are still scarce. When surveying the representativeness of the CoVs and PMVs found and the available genomic sequences, it can be perceived that there may be gaps in the knowledge. The continuous monitoring of viral sequences that are closely related to human pathogens may be helpful in mapping and predicting future hotspots in the emergence of zoonotic agents.

RNA virus diversity in rodents

Many zoonotic disease emergencies are associated with RNA viruses in rodents that substantially impact public health. With the widespread application of meta-genomics and meta-transcriptomics for virus discovery over the last decade, viral sequences deposited in public databases have expanded rapidly, and the number of novel viruses discovered in rodents has increased. As important reservoirs of zoonotic viruses, rodents have attracted increasing attention for the risk of potential spillover of rodent-borne viruses. However, knowledge of rodent viral diversity and the major factors contributing to the risk of zoonotic epidemic outbreaks remains limited. Therefore, this study analyzes the diversity and composition of rodent RNA viruses using virus records from the Database of Rodent-associated Viruses (DRodVir/ZOVER), which covers the published literatures and records in GenBank database, reviews the main rodent RNA virus-induced human infectious diseases, and discusses potential challenges in this field.

Regulation of host gene expression by J paramyxovirus

Paramyxoviruses are negative-sense, single-stranded RNA viruses that are associated with numerous diseases in humans and animals. J paramyxovirus (JPV) was first isolated from moribund mice (Mus musculus) with hemorrhagic lung lesions in Australia in 1972. In 2016, JPV was classified into the newly established genus Jeilongvirus. Novel jeilongviruses are being discovered worldwide in wildlife populations. However, the effects of jeilongvirus infection on host gene expression remains uncharacterized. To address this, cellular RNA from JPV-infected mouse fibroblasts was collected at 2, 4, 8, 12, 16, 24, and 48 hours post-infection (hpi) and were sequenced using single-end 75 base pairs (SE75) sequencing chemistry on an Illumina NextSeq platform. Differentially expressed genes (DEGs) between the virus-infected replicates and mock replicates at each timepoint were identified using the Tophat2-Cufflinks-Cuffdiff protocol. At 2 hpi, 11 DEGs were identified in JPV-infected cells, while 1,837 DEGs were detected at 48 hpi. A GO analysis determined that the genes at the earlier timepoints were involved in interferon responses, while there was a shift towards genes that are involved in antigen processing and presentation processes at the later timepoints. At 48 hpi, a KEGG analysis revealed that many of the DEGs detected were involved in pathways that are important for immune responses. qRT-PCR verified that Rtp4, Ifit3, Mx2, and Stat2 were all upregulated during JPV infection, while G0s2 was downregulated. After JPV infection, the expression of inflammatory and antiviral factors in mouse fibroblasts changes significantly. This study provides crucial insight into the different arms of host immunity that mediate Jeilongvirus infection. Understanding the pathogenic mechanisms of Jeilongvirus will lead to better strategies for the prevention and control of potential diseases that may arise from this group of viruses.

Discovery and genome characterization of six new orthoparamyxoviruses in small Belgian mammals

In the future, zoonotic spillover events are expected to occur more frequently. Consequences of such events have clearly been demonstrated by recent outbreaks of monkeypox, Ebola virus, and the well-known severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Virus discovery has proven to be an important tool in the preparation against viral outbreaks, generating data concerning the diversity, quantity, and ecology of the vertebrate virome. Orthoparamyxoviruses, a subfamily within the Paramyxoviridae, are important biosurveillance targets, since they include several known animal, human, and zoonotic pathogens such as Nipah virus, measles virus, and Hendra virus. During this study, 127 bat samples, thirty-four rodent samples, and seventeen shrew samples originating from Belgium were screened for orthoparamyxovirus presence using nested reverse transcription-polymerase chain reaction assays and nanopore sequencing. We present here the complete genomes of six putative new viral species, belonging to the genera Jeilongvirus and Henipavirus. Characterization of these genomes revealed significant differences in gene composition and organization, both within viruses of the same genus and between viruses of different genera. Remarkably, a previously undetected gene coding for a protein of unknown function was identified in the genome of a putative new Henipavirus. Additionally, phylogenetic analysis of jeilongviruses and henipaviruses reveals a division of both genera into two clades, one consisting of bat-borne viruses and the other consisting of rodent- and shrew-borne viruses, elucidating the need for proper reclassification.

Metagenomics-enabled reverse-genetics assembly and characterization of myotis bat morbillivirus

Morbilliviruses are among the most contagious viral pathogens of mammals. Although previous metagenomic surveys have identified morbillivirus sequences in bats, full-length morbilliviruses from bats are limited. Here we characterize the myotis bat morbillivirus (MBaMV) from a bat surveillance programme in Brazil, whose full genome was recently published. We demonstrate that the fusion and receptor binding protein of MBaMV utilize bat CD150 and not human CD150, as an entry receptor in a mammalian cell line. Using reverse genetics, we produced a clone of MBaMV that infected Vero cells expressing bat CD150. Electron microscopy of MBaMV-infected cells revealed budding of pleomorphic virions, a characteristic morbillivirus feature. MBaMV replication reached 103-105 plaque-forming units ml-1 in human epithelial cell lines and was dependent on nectin-4. Infection of human macrophages also occurred, albeit 2-10-fold less efficiently than measles virus. Importantly, MBaMV is restricted by cross-neutralizing human sera elicited by measles, mumps and rubella vaccination and is inhibited by orally bioavailable polymerase inhibitors in vitro. MBaMV-encoded P/V genes did not antagonize human interferon induction. Finally, we show that MBaMV does not cause disease in Jamaican fruit bats. We conclude that, while zoonotic spillover into humans may theoretically be plausible, MBaMV replication would probably be controlled by the human immune system.

Isolation and Molecular Characterisation of Respirovirus 3 in Wild Boar

Paramyxoviruses are important pathogens affecting various animals, including humans. In this study, we identified a paramyxovirus in 2004 (180608_2004), isolated from a sample of the femoral marrow bone of a wild boar carcass imported from Australia. Antigenic and morphological characteristics indicated that this virus was similar to members of the family Paramyxoviridae. The complete genome phylogenetic analysis grouped this virus into genotype A of bovine parainfluenza virus type 3 (BPIV-3), recently renamed bovine respirovirus type 3 (BRV3), which also includes two swine paramyxoviruses (SPMV)-Texas-81 and ISU-92-isolated from encephalitic pigs in the United States in 1982 and 1992, respectively. The wild boar 180608_2004 strain was more closely related to both the BRV3 shipping fever (SF) strain and the SPMV Texas-81 strain at the nucleotide and amino acid levels than the SPMV ISU-92 strain. The high sequence identity to BRV3 suggested that this virus can be transferred from cattle to wild boars. The potential for cross-species transmission in the Respirovirus genus makes it essential for intensified genomic surveillance.

Diverse DNA virus genomes identified in fecal samples of Mexican free-tailed bats (Tadarida brasiliensis) captured in Chiricahua Mountains of southeast Arizona (USA)

Bats (order Chiroptera) are some of the most abundant mammals on earth and their species ecology strongly influences zoonotic potential. While substantial research has been conducted on bat-associated viruses, particularly on those that can cause disease in humans and/or livestock, globally, limited research has focused on endemic bats in the USA. The southwest region of the US is of particular interest because of its high diversity of bat species. We identified 39 single-stranded DNA virus genomes in the feces of Mexican free-tailed bats (Tadarida brasiliensis) sampled in the Rucker Canyon (Chiricahua Mountains) of southeast Arizona (USA). Twenty-eight of these belong to the virus families Circoviridae (n = 6), Genomoviridae (n = 17), and Microviridae (n = 5). Eleven viruses cluster with other unclassified cressdnaviruses. Most of the viruses identified represent new species. Further research on identification of novel bat-associated cressdnaviruses and microviruses is needed to provide greater insights regarding their co-evolution and ecology relative to bats.

Paramyxoviruses from bats: changes in receptor specificity and their role in host adaptation

Global metagenomic surveys have revealed that bats host a diverse array of paramyxoviruses, including species from at least five major genera. An essential determinant of successful spillover is the entry of a virus into a new host. We evaluate the role of receptor usage in the zoonotic potential of bat-borne henipaviruses, morbilliviruses, pararubulaviruses, orthorubulaviruses, and jeilongviruses; successful spillover into humans depends upon compatibility of a respective viral attachment protein with its cognate receptor. We also emphasize the importance of postentry restrictions in preventing spillover. Metagenomics and characterization of newly identified paramyxoviruses have greatly improved our understanding of spillover determinants, allowing for better forecasts of which bat-borne viruses may pose the greatest risk for cross-species transmission into humans.

The C-Terminal 300 Amino Acid Residues of the G Protein and Putative Open Reading Frame X of the G Gene of Tailam Paramyxovirus (TlmPV) Are Not Required for Replication in Tissue Culture Cells

Tailam paramyxovirus (TlmPV) was identified in Sikkim Rats in Hong Kong, China in 2011. Its negative sense RNA genome is similar to J paramyxovirus (JPV) and Beilong paramyxovirus (BeiPV), the prototypes of the recently established genus Jeilongvirus. TlmPV genome is predicted to have eight genes in the order 3'-N-P/V/C-M-F-SH-TM-G/X-L-5'. The predicted size of the TlmPV G protein is 1,052 amino acid (aa) residues and much larger than G proteins of typical paramyxoviruses, which are often less than 800 aa. In addition to G open reading frame (ORF) in the G gene, another ORF, termed ORF-X exists in the G gene transcript. Similar ORF-X exists in JPV and BeiPV G gene, but their expression in virus-infected cells has not been confirmed. In this study, we generated infectious TlmPV using a newly developed reverse genetics system. We have found that the G protein of TlmPV is truncated in cultured cells: stop codons emerged in the G open reading frame, resulting in deletions of amino acid residues beyond residue 732. We have obtained infectious TlmPV lacking the C-terminal 307 aa (rTlmPV-G745) and TlmPV lacking the C-terminal 306 aa and the ORF-X (rTlmPV-GΔ746-X). The recombinant TlmPVs lacking the C-terminal 300 aa reach a higher peak viral titer and have improved genome stability in tissue cultured cells. The work indicates that the C-terminal of the G protein of TlmPV and ORF-X are not required for replication in tissue culture cells, and the deletion of the C-terminal confers a growth advantage in tissue culture cells. IMPORTANCE TlmPV is a member of the recently established genus Jeilongvirus. TlmPV encodes a large G protein and its G gene contains ORF-X. In this work, infectious TlmPV was recovered using reverse genetics. Using this system, we have demonstrated that 300 aa of C-terminal of G and the ORF-X are not required for viral replication in tissue culture cells.

The Characterization of Multiple Novel Paramyxoviruses Highlights the Diverse Nature of the Subfamily Orthoparamyxovirinae

The subfamily Orthoparamyxovirinae is a group of single-stranded, negative-sense RNA viruses that contains many human, animal, and zoonotic pathogens. While there are currently only forty-two recognized species in this subfamily, recent research has revealed that much of its diversity remains to be characterized. Using a newly developed nested PCR-based screening assay, we report here the discovery of fifteen orthoparamyxoviruses in rodents and shrews from Belgium and Guinea, thirteen of which are believed to represent new species. Using a combination of nanopore and sanger sequencing, complete genomes could be determined for almost all these viruses, enabling a detailed evaluation of their genome characteristics. While most viruses are thought to belong to the rapidly expanding genus Jeilongvirus, we also identify novel members of the genera Narmovirus, Henipavirus, and Morbillivirus. Together with other recently discovered orthoparamyxoviruses, both henipaviruses and the morbillivirus discovered here appear to form distinct rodent-/shrew-borne clades within their respective genera, clustering separately from all currently classified viruses. In the case of the henipaviruses, a comparison of the different members of this clade revealed the presence of a secondary conserved open reading frame, encoding for a transmembrane protein, within the F gene, the biological relevance of which remains to be established. While the characteristics of the viruses described here shed further light on the complex evolutionary origin of paramyxoviruses, they also illustrate that the diversity of this group of viruses in terms of genome organization appears to be much larger than previously assumed.

Paramyxovirus Diversity within One Population of Miniopterus fuliginosus Bats in Sri Lanka

Bats are known as typical reservoirs for a number of viruses, including viruses of the family Paramyxoviridae. Representatives of the subfamily Orthoparamyxovirinae are distributed worldwide and can cause mild to fatal diseases when infecting humans. The research on Paramyxoviruses (PMVs) from different bat hosts all over the world aims to understand the diversity, evolution and distribution of these viruses and to assess their zoonotic potential. A high number of yet unclassified PMVs from bats are recorded. In our study, we investigated bat species from the families Rhinolophidae, Hipposiderae, Pteropodidae and Miniopteridae that are roosting sympatrically in the Wavul Galge cave (Koslanda, Sri Lanka). The sampling at three time points (March and July 2018; January 2019) and screening for PMVs with a generic PCR show the presence of different novel PMVs in 10 urine samples collected from Miniopterus fuliginosus. Sequence analysis revealed a high similarity of the novel strains among each other and to other unclassified PMVs collected from Miniopterus bats. In this study, we present the first detection of PMVs in Sri Lanka and the presence of PMVs in the bat species M. fuliginosus for the first time.

Discovery of three cycloviruses in fecal samples from silver-haired bats (Lasionycteris noctivagans) in Arizona (USA)

Bats harbour a diverse array of viruses, some of which are zoonotic, and are one of the most speciose groups of mammals on earth. As part of an ongoing bat-associated viral diversity research project, we identified three cycloviruses (family Circoviridae) in fecal samples of silver-haired bats (Lasionycteris noctivagans) caught in Cave Creek Canyon of Arizona (USA). Two of the three identified genomes represent two new species in the genus Cyclovirus. Cycloviruses have been found in a wide range of environments and hosts; however, little is known about their biology. These new genomes of cycloviruses are the first from silver-haired bats, adding to the broader knowledge of cyclovirus diversity. With continuing studies, it is likely that additional viruses of the family Circoviridae will be identified in Arizona bat populations.