Prevention of respiratory virus transmission by resident memory CD8+ T cells.

An ideal vaccine both attenuates virus growth and disease in infected individuals and reduces the spread of infections in the population, thereby generating herd immunity. Although this strategy has proved successful by generating humoral immunity to measles, yellow fever and polio, many respiratory viruses evolve to evade pre-existing antibodies1. One approach for improving the breadth of antiviral immunity against escape variants is through the generation of memory T cells in the respiratory tract, which are positioned to respond rapidly to respiratory virus infections2-6. However, it is unknown whether memory T cells alone can effectively surveil the respiratory tract to the extent that they eliminate or greatly reduce viral transmission following exposure of an individual to infection. Here we use a mouse model of natural parainfluenza virus transmission to quantify the extent to which memory CD8+ T cells resident in the respiratory tract can provide herd immunity by reducing both the susceptibility of acquiring infection and the extent of transmission, even in the absence of virus-specific antibodies. We demonstrate that protection by resident memory CD8+ T cells requires the antiviral cytokine interferon-γ (IFNγ) and leads to altered transcriptional programming of epithelial cells within the respiratory tract. These results suggest that tissue-resident CD8+ T cells in the respiratory tract can have important roles in protecting the host against viral disease and limiting viral spread throughout the population.

Tissue replication and mucosal swab detection of Sosuga virus in Syrian hamsters in the absence of overt tissue pathology and clinical disease.

Human infection with Sosuga virus (SOSV), a recently discovered pathogenic paramyxovirus, has been reported in one individual to date. No animal models of disease are currently available for SOSV. Here, we describe initial characterization of experimental infection in Syrian hamsters, including kinetics of virus dissemination and replication, and the corresponding clinical parameters, immunological responses, and histopathology. We demonstrate susceptibility of hamsters to infection in the absence of clinical signs or significant histopathologic findings in tissues.

Highly Potent Host-Specific Small-Molecule Inhibitor of Paramyxovirus and Pneumovirus Replication with High Resistance Barrier.

Multiple enveloped RNA viruses of the family Paramyxoviridae and Pneumoviridae, like measles virus (MeV), Nipah virus (NiV), canine distemper virus (CDV), or respiratory syncytial virus (RSV), are of high clinical relevance. Each year a huge number of lives are lost as a result of these viral infections. Worldwide, MeV infection alone is responsible for over a hundred thousand deaths each year despite available vaccine. Therefore, there is an urgent need for treatment options to counteract these viral infections. The development of antiviral drugs in general stands as a huge challenge due to the rapid emergence of viral escape mutants. Here, we disclose the discovery of a small-molecule antiviral, compound 1 (ZHAWOC9045), active against several pneumo-/paramyxoviruses, including MeV, NiV, CDV, RSV, and parainfluenza virus type 5 (PIV-5). A series of mechanistic characterizations revealed that compound 1 targets a host factor which is indispensable for viral genome replication. Drug resistance profiling against a paramyxovirus model (CDV) demonstrated no detectable adaptation despite prolonged time of investigation, thereby mitigating the rapid emergence of escape variants. Furthermore, a thorough structure-activity relationship analysis of compound 1 led to the invention of 100-times-more potent-derivatives, e.g., compound 2 (ZHAWOC21026). Collectively, we present in this study an attractive host-directed pneumoviral/paramyxoviral replication inhibitor with potential therapeutic application. IMPORTANCE Measles virus, respiratory syncytial virus, canine distemper virus, and Nipah virus are some of the clinically significant RNA viruses that threaten substantial number of lives each year. Limited to no availability of treatment options for these viral infections makes it arduous to handle the outbreaks. This highlights the major importance of developing antivirals to fight not only ongoing infections but also potential future epidemics. Most of the discovered antivirals, in clinical trials currently, are virus targeted, which consequently poses the challenge of rapid emergence of escape variants. Here, we present compound 1 (ZHAWOC9045), discovered to target viral replication in a host-dependent manner, thereby exhibiting broad-spectrum activity against several members of the family Pneumo-/Paramyxoviridae. The inability of viruses to mutate against the inhibitor mitigated the critical issue of generation of escape variants. Importantly, compound 1 was successfully optimized to a highly potent variant, compound 2 (ZHAWOC21026), with a promising profile for pharmacological intervention.

Paramyxoviruses from neotropical bats suggest a novel genus and nephrotropism.

Paramyxoviruses have a broad host range and geographic distribution, including human pathogens transmitted by bats, such as Nipah and Hendra viruses. In this study, we combined high-throughput sequencing and molecular approaches to investigate the presence of paramyxoviruses in neotropical bats (Microchiroptera suborder) in Brazil. We discovered and characterized three novel paramyxoviruses in the kidney tissues of apparently healthy common vampire bats (D. rotundus) and Seba's short-tailed bats (C. perspicillata), which we tentatively named Kanhgág virus (KANV), Boe virus (BOEV), and Guató virus (GUATV). In this study, we classified these viruses as putative species into the Macrojêvirus genus, a newly proposed genus of the Orthoparamyxovirinae subfamily. Using RT-PCR, we detected these viruses in 20.9% (9 out of 43) of bats tested, and viral RNA was detected exclusively in kidney tissues. Attempts to isolate infectious virus were successful for KANV and GUATV. Our results expand the viral diversity, host range, and geographical distribution of the paramyxoviruses.

Paramyxovirus circulation in bat species from French Guiana.

Bats are recognized as reservoirs of numerous viruses. Among them, paramyxoviruses, for example, Hendra and Nipah viruses, are highly pathogenic to humans. Nothing is known regarding the circulation of this viral family in bats from French Guiana. To search for the presence of paramyxoviruses in this territory, 103 bats of seven different species were sampled and screened using a molecular approach. Four distinct paramyxovirus sequences were detected from three bat species (Desmodus rotundus, Carollia perspicillata, and Pteronotus alitonus) at high prevalence rates. In D. rotundus, two types of paramyxovirus co-circulate, with most of the bats co-infected. The phylogenetic analysis of these sequences revealed that three of them were closely related to previously characterized sequences from D. rotundus, C. perspicillata, and P. parnellii from Brazil and Costa Rica. The fourth sequence, identified in D. rotundus, was closely related to the one detected in P. alitonus in French Guiana and to previously described sequences detected in P. parnellii in Costa Rica. All paramyxovirus sequences detected in this study are close to the Jeilongvirus genus. Altogether, our results and those of previous studies indicate a wide geographical distribution of these paramyxoviruses (from Central to South America) and suggest potential cross-species transmissions of paramyxoviruses between two different bat families: Mormoopidae (P. alitonus) and Phyllostomidae (D. rotundus). In addition, their closeness to paramyxoviruses identified in rodents emphasizes the need to investigate the role of these animals as potential reservoirs or incidental hosts. Finally, the high prevalence rates of some paramyxoviruses in certain bat species, associated with the presence of large bat colonies and, in some cases, their potential proximity with humans are all parameters that can contribute to the risk of cross-species transmission between bat species and to the emergence of new paramyxoviruses in humans, a risk that deserves further investigation.

Viperin protein inhibits the replication of caprine parainfluenza virus type 3 (CPIV 3) by interaction with viral N protein.

Caprine parainfluenza virus type3 (CPIV3) is a newly identified member of Paramyxoviridae family. CPIV3 is highly prevalence in China and showed pathogenicity to goats; in addition, CPIV3 infection causes severe clinical disease under stress and/or co-infection conditions. Viperin is one of the hundreds of interferon-stimulated genes (ISGs), and possesses a wide range of antiviral activities. The aim of this study was to systemically explore the anti-CPIV3 activity of ruminants' Viperin. CPIV3 infection up-regulated Viperin transcription but not protein expression in MDBK cells. Bovine and caprine Viperin genes (bVi and gVi) were amplified and analyzed by BLAST and multiple alignment. The obtained bVi/gVi amino acid sequences showed 99.5%-100% identity with previously submitted sequences and has variants at N-terminal domain (1-70aa) between each other. The pcDNA3.1 plasmids containing bVi and gVi genes were constructed to over-express the target proteins. CPIV3 was inoculated in MDBK cells over-expressing bVi/gVi and viral load was detected by qRT-PCR, virus titration and Western blot. Both of the bVi and gVi significantly inhibited CPIV3 genome copy numbers and viral titers at 24 and 48 hpi (P < 0.01); and viral N protein expression was also decreased, comparing with those of mock transfected group. The last 50aa C-terminal region was crucial for its anti-CPIV3 activity. In addition, the over-expression of bVi/gVi did not influence CPIV3 binding, entry and release in the cells. These results indicated the anti-CPIV3 activity occurred in viral RNA/protein synthesis progress of the viral replication cycle. The Viperin also showed similar inhibitory effect on different CPIV3 strains. The potential interaction of Viperin with viral proteins (N, P, C and V) was determined by confocal laser scanning microscopy and Co-IP assay. Co-localization of Viperin with N, P or C, but not V, was observed; while only N protein direct interacted with Viperin in Co-IP test, no matter using viral protein expressing plasmids transfected or CPIV3 infected cell samples. In conclusion, the bVi and gVi Viperin effectively inhibited CPIV3 replication potentially via the interaction of Viperin with viral N protein. The present results gave more information about antiviral activity of ruminants Viperin and provided foundation for further studies of the interaction of Viperin with CPIV3 and other related viruses.

Differential Features of Fusion Activation within the Paramyxoviridae.

Paramyxovirus (PMV) entry requires the coordinated action of two envelope glycoproteins, the receptor binding protein (RBP) and fusion protein (F). The sequence of events that occurs during the PMV entry process is tightly regulated. This regulation ensures entry will only initiate when the virion is in the vicinity of a target cell membrane. Here, we review recent structural and mechanistic studies to delineate the entry features that are shared and distinct amongst the Paramyxoviridae. In general, we observe overarching distinctions between the protein-using RBPs and the sialic acid- (SA-) using RBPs, including how their stalk domains differentially trigger F. Moreover, through sequence comparisons, we identify greater structural and functional conservation amongst the PMV fusion proteins, as compared to the RBPs. When examining the relative contributions to sequence conservation of the globular head versus stalk domains of the RBP, we observe that, for the protein-using PMVs, the stalk domains exhibit higher conservation and find the opposite trend is true for SA-using PMVs. A better understanding of conserved and distinct features that govern the entry of protein-using versus SA-using PMVs will inform the rational design of broader spectrum therapeutics that impede this process.

Receptor-mediated cell entry of paramyxoviruses: Mechanisms, and consequences for tropism and pathogenesis.

Research in the last decade has uncovered many new paramyxoviruses, airborne agents that cause epidemic diseases in animals including humans. Most paramyxoviruses enter epithelial cells of the airway using sialic acid as a receptor and cause only mild disease. However, others cross the epithelial barrier and cause more severe disease. For some of these viruses, the host receptors have been identified, and the mechanisms of cell entry have been elucidated. The tetrameric attachment proteins of paramyxoviruses have vastly different binding affinities for their cognate receptors, which they contact through different binding surfaces. Nevertheless, all input signals are converted to the same output: conformational changes that trigger refolding of trimeric fusion proteins and membrane fusion. Experiments with selectively receptor-blinded viruses inoculated into their natural hosts have provided insights into tropism, identifying the cells and tissues that support growth and revealing the mechanisms of pathogenesis. These analyses also shed light on diabolically elegant mechanisms used by morbilliviruses, including the measles virus, to promote massive amplification within the host, followed by efficient aerosolization and rapid spread through host populations. In another paradigm of receptor-facilitated severe disease, henipaviruses, including Nipah and Hendra viruses, use different members of one protein family to cause zoonoses. Specific properties of different paramyxoviruses, like neurotoxicity and immunosuppression, are now understood in the light of receptor specificity. We propose that research on the specific receptors for several newly identified members of the Paramyxoviridae family that may not bind sialic acid is needed to anticipate their zoonotic potential and to generate effective vaccines and antiviral compounds.

Distinct Chronic Post-Viral Lung Diseases upon Infection with Influenza or Parainfluenza Viruses Differentially Impact Superinfection Outcome.

Chronic obstructive pulmonary disease (COPD) and asthma remain prevalent human lung diseases. Variability in epithelial and inflammatory components that results in pathologic heterogeneity complicates the development of treatments for these diseases. Early childhood infection with parainfluenza virus or respiratory syncytial virus is strongly associated with the development of asthma and COPD later in life, and exacerbations of these diseases correlate with the presence of viral RNA in the lung. Well-characterized animal models of postviral chronic lung diseases are necessary to study the underlying mechanisms of viral-related COPD and asthma and to develop appropriate therapies. In this study, we cross-analyzed chronic lung disease caused by infection with Sendai virus (SeV) or influenza A virus in mice. Differences were observed in lesion composition and inflammatory profiles between SeV- and influenza A virus-induced long-term lung disease. In addition, a primary SeV infection led to worsened pathologic findings on secondary heterologous viral challenge, whereas the reversed infection scheme protected against disease in response to a secondary viral challenge >1 month after the primary infection. These data demonstrate the differential effect of primary viral infections in the susceptibility to disease exacerbation in response to a different secondary viral infection and highlight the usefulness of these viral models as tools to understand the underlying mechanisms that mediate distinct chronic postviral lung diseases.

A structure-based rationale for sialic acid independent host-cell entry of Sosuga virus.

The bat-borne paramyxovirus, Sosuga virus (SosV), is one of many paramyxoviruses recently identified and classified within the newly established genus Pararubulavirus, family Paramyxoviridae The envelope surface of SosV presents a receptor-binding protein (RBP), SosV-RBP, which facilitates host-cell attachment and entry. Unlike closely related hemagglutinin neuraminidase RBPs from other genera of the Paramyxoviridae, SosV-RBP and other pararubulavirus RBPs lack many of the stringently conserved residues required for sialic acid recognition and hydrolysis. We determined the crystal structure of the globular head region of SosV-RBP, revealing that while the glycoprotein presents a classical paramyxoviral six-bladed ß-propeller fold and structurally classifies in close proximity to paramyxoviral RBPs with hemagglutinin-neuraminidase (HN) functionality, it presents a receptor-binding face incongruent with sialic acid recognition. Hemadsorption and neuraminidase activity analysis confirms the limited capacity of SosV-RBP to interact with sialic acid in vitro and indicates that SosV-RBP undergoes a nonclassical route of host-cell entry. The close overall structural conservation of SosV-RBP with other classical HN RBPs supports a model by which pararubulaviruses only recently diverged from sialic acid binding functionality.

ICTV Virus Taxonomy Profile: Paramyxoviridae.

The family Paramyxoviridae consists of large enveloped RNA viruses infecting mammals, birds, reptiles and fish. Many paramyxoviruses are host-specific and several, such as measles virus, mumps virus, Nipah virus, Hendra virus and several parainfluenza viruses, are pathogenic for humans. The transmission of paramyxoviruses is horizontal, mainly through airborne routes; no vectors are known. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the family Paramyxoviridae. which is available at ictv.global/report/paramyxoviridae.

Three genetically distinct ferlaviruses have varying effects on infected corn snakes (Pantherophis guttatus).

Ferlaviruses are important pathogens in snakes and other reptiles. They cause respiratory and neurological disease in infected animals and can cause severe disease outbreaks. Isolates from this genus can be divided into four genogroups-A, B, and C, as well as a more distantly related sister group, "tortoise". Sequences from large portions (5.3 kb) of the genomes of a variety of ferlavirus isolates from genogroups A, B, and C, including the genes coding the surface glycoproteins F and HN as well as the L protein were determined and compared. In silico analyses of the glycoproteins of genogroup A, B, and C isolates were carried out. Three isolates representing these three genogroups were used in transmission studies with corn snakes (Pantherophis guttatus), and clinical signs, gross and histopathology, electronmicroscopic changes in the lungs, and isolation of bacteria from the lungs were evaluated. Analysis of the sequences supported the previous categorization of ferlaviruses into four genogroups, and criteria for definition of ferlavirus genogroups and species were established based on sequence identities (80% resp. 90%). Analysis of the ferlavirus glycoprotein models showed parallels to corresponding regions of other paramyxoviruses. The transmission studies showed clear differences in the pathogenicities of the three virus isolates used. The genogroup B isolate was the most and the group A virus the least pathogenic. Reasons for these differences were not clear based on the differences in the putative structures of their respective glycoproteins, although e.g. residue and consequential structure variation of an extended cleavage site or changes in electrostatic charges at enzyme binding sites could play a role. The presence of bacteria in the lungs of the infected animals also clearly corresponded to increased pathogenicity. This study contributes to knowledge about the structure and phylogeny of ferlaviruses and lucidly demonstrates differences in pathogenicity between strains of different genogroups.

Bipartite promoters and RNA editing of paramyxoviruses and filoviruses.

A primary property of paramyxovirus bipartite promoters is to ensure that their RNA genomes are imprinted with a hexamer phase via their association with nucleoproteins, in part because this phase as well the editing sequence itself controls mRNA editing. The question then arises whether a similar mechanism operates for filoviruses that also contain bipartite promoters that are governed by the "rule of six," even though these genomes need not, and given Ebola virus biology, cannot always be of hexamer genome length. This review suggests that this is possible and describes how it might operate, and that RNA editing may play a role in Ebola virus genome interconversion that helps the virus adapt to different host environments.

Animal infection studies of two recently discovered African bat paramyxoviruses, Achimota 1 and Achimota 2.

Bats are implicated as the natural reservoirs for several highly pathogenic viruses that can infect other animal species, including man. Here, we investigate the potential for two recently discovered bat rubulaviruses, Achimota virus 1 (AchPV1) and Achimota virus 2 (AchPV2), isolated from urine collected under urban bat (Eidolon helvum) roosts in Ghana, West Africa, to infect small laboratory animals. AchPV1 and AchPV2 are classified in the family Paramyxoviridae and cluster with other bat derived zoonotic rubulaviruses (i.e. Sosuga, Menangle and Tioman viruses). To assess the susceptibility of AchPV1 and AchPV2 in animals, infection studies were conducted in ferrets, guinea pigs and mice. Seroconversion, immunohistological evidence of infection, and viral shedding were identified in ferrets and guinea pigs, but not in mice. Infection was associated with respiratory disease in ferrets. Viral genome was detected in a range of tissues from ferrets and guinea pigs, however virus isolation was only achieved from ferret tissues. The results from this study indicate Achimota viruses (AchPVs) are able to cross the species barrier. Consequently, vigilance for infection with and disease caused by these viruses in people and domesticated animals is warranted in sub-Saharan Africa and the Arabian Peninsula where the reservoir hosts are present.

Nitazoxanide inhibits paramyxovirus replication by targeting the Fusion protein folding: role of glycoprotein-specific thiol oxidoreductase ERp57.

Paramyxoviridae, a large family of enveloped viruses harboring a nonsegmented negative-sense RNA genome, include important human pathogens as measles, mumps, respiratory syncytial virus (RSV), parainfluenza viruses, and henipaviruses, which cause some of the deadliest emerging zoonoses. There is no effective antiviral chemotherapy for most of these pathogens. Paramyxoviruses evolved a sophisticated membrane-fusion machine consisting of receptor-binding proteins and the fusion F-protein, critical for virus infectivity. Herein we identify the antiprotozoal/antimicrobial nitazoxanide as a potential anti-paramyxovirus drug targeting the F-protein. We show that nitazoxanide and its circulating-metabolite tizoxanide act at post-entry level by provoking Sendai virus and RSV F-protein aggregate formation, halting F-trafficking to the host plasma membrane. F-protein folding depends on ER-resident glycoprotein-specific thiol-oxidoreductase ERp57 for correct disulfide-bond architecture. We found that tizoxanide behaves as an ERp57 non-competitive inhibitor; the putative drug binding-site was located at the ERp57-b/b' non-catalytic domains interface. ERp57-silencing mimicked thiazolide-induced F-protein alterations, suggesting an important role of this foldase in thiazolides anti-paramyxovirus activity. Nitazoxanide is used in the clinic as a safe and effective antiprotozoal/antimicrobial drug; its antiviral activity was shown in patients infected with hepatitis-C virus, rotavirus and influenza viruses. Our results now suggest that nitazoxanide may be effective also against paramyxovirus infection.

Development of a reverse genetics system for Sosuga virus allows rapid screening of antiviral compounds.

Sosuga virus (SOSV) is a recently discovered zoonotic paramyxovirus isolated from a single human case in 2012; it has been ecologically and epidemiologically associated with transmission by the Egyptian rousette bat (Rousettus aegyptiacus). Bats have long been recognized as sources of novel zoonotic pathogens, including highly lethal paramyxoviruses like Nipah virus (NiV) and Hendra virus (HeV). The ability of SOSV to cause severe human disease supports the need for studies on SOSV pathogenesis to better understand the potential impact of this virus and to identify effective treatments. Here we describe a reverse genetics system for SOSV comprising a minigenome-based assay and a replication-competent infectious recombinant reporter SOSV that expresses the fluorescent protein ZsGreen1 in infected cells. First, we used the minigenome assay to rapidly screen for compounds inhibiting SOSV replication at biosafety level 2 (BSL-2). The antiviral activity of candidate compounds was then tested against authentic viral replication using the reporter SOSV at BSL-3. We identified several compounds with anti-SOSV activity, several of which also inhibit NiV and HeV. Alongside its utility in screening for potential SOSV therapeutics, the reverse genetics system described here is a powerful tool for analyzing mechanisms of SOSV pathogenesis, which will facilitate our understanding of how to combat the potential public health threats posed by emerging bat-borne paramyxoviruses.

Paramyxovirus V Proteins Interact with the RIG-I/TRIM25 Regulatory Complex and Inhibit RIG-I Signaling.

Paramyxovirus V proteins are known antagonists of the RIG-I-like receptor (RLR)-mediated interferon induction pathway, interacting with and inhibiting the RLR MDA5. We report interactions between the Nipah virus V protein and both RIG-I regulatory protein TRIM25 and RIG-I. We also observed interactions between these host proteins and the V proteins of measles virus, Sendai virus, and parainfluenza virus. These interactions are mediated by the conserved C-terminal domain of the V protein, which binds to the tandem caspase activation and recruitment domains (CARDs) of RIG-I (the region of TRIM25 ubiquitination) and to the SPRY domain of TRIM25, which mediates TRIM25 interaction with the RIG-I CARDs. Furthermore, we show that V interaction with TRIM25 and RIG-I prevents TRIM25-mediated ubiquitination of RIG-I and disrupts downstream RIG-I signaling to the mitochondrial antiviral signaling protein. This is a novel mechanism for innate immune inhibition by paramyxovirus V proteins, distinct from other known V protein functions such as MDA5 and STAT1 antagonism.IMPORTANCE The host RIG-I signaling pathway is a key early obstacle to paramyxovirus infection, as it results in rapid induction of an antiviral response. This study shows that paramyxovirus V proteins interact with and inhibit the activation of RIG-I, thereby interrupting the antiviral signaling pathway and facilitating virus replication.

Diverse Viruses Require the Calcium Transporter SPCA1 for Maturation and Spread.

Respiratory and arthropod-borne viral infections are a global threat due to the lack of effective antivirals and vaccines. A potential strategy is to target host proteins required for viruses but non-essential for the host. To identify such proteins, we performed a genome-wide knockout screen in human haploid cells and identified the calcium pump SPCA1. SPCA1 is required by viruses from the Paramyxoviridae, Flaviviridae, and Togaviridae families, including measles, dengue, West Nile, Zika, and chikungunya viruses. Calcium transport activity is required for SPCA1 to promote virus spread. SPCA1 regulates proteases within the trans-Golgi network that require calcium for their activity and are critical for virus glycoprotein maturation. Consistent with these findings, viral glycoproteins fail to mature in SPCA1-deficient cells preventing viral spread, which is evident even in cells with partial loss of SPCA1. Thus, SPCA1 is an attractive antiviral host target for a broad spectrum of established and emerging viral infections.

A Tupaia paramyxovirus vector system for targeting and transgene expression.

Viruses from the diverse family of Paramyxoviridae include important pathogens and are applied in gene therapy and for cancer treatment. The Tupaia paramyxovirus (TPMV), isolated from the kidney of a tree shrew, does not infect human cells and neutralizing antibodies against other Paramyxoviridae do not cross-react with TPMV. Here, we present a vector system for de novo generation of infectious TPMV that allows for insertion of additional genes as well as targeting using antibody single-chain variable fragments. We show that the recombinant TPMV specifically infect cells expressing the targeted receptor and replicate in human cells. This vector system provides a valuable tool for both basic research and therapeutic applications.

Idiosyncratic Mòjiang virus attachment glycoprotein directs a host-cell entry pathway distinct from genetically related henipaviruses.

In 2012, cases of lethal pneumonia among Chinese miners prompted the isolation of a rat-borne henipavirus (HNV), Mòjiang virus (MojV). Although MojV is genetically related to highly pathogenic bat-borne henipaviruses, the absence of a conserved ephrin receptor-binding motif in the MojV attachment glycoprotein (MojV-G) indicates a differing host-cell recognition mechanism. Here we find that MojV-G displays a six-bladed ß-propeller fold bearing limited similarity to known paramyxoviral attachment glycoproteins, in particular at host receptor-binding surfaces. We confirm the inability of MojV-G to interact with known paramyxoviral receptors in vitro, indicating an independence from well-characterized ephrinB2/B3, sialic acid and CD150-mediated entry pathways. Furthermore, we find that MojV-G is antigenically distinct, indicating that MojV would less likely be detected in existing large-scale serological screening studies focused on well-established HNVs. Altogether, these data indicate a unique host-cell entry pathway for this emerging and potentially pathogenic HNV.