Integrated cryoEM structure of a spumaretrovirus reveals cross-kingdom evolutionary relationships and the molecular basis for assembly and virus entry.

Foamy viruses (FVs) are an ancient lineage of retroviruses, with an evolutionary history spanning over 450 million years. Vector systems based on Prototype Foamy Virus (PFV) are promising candidates for gene and oncolytic therapies. Structural studies of PFV contribute to the understanding of the mechanisms of FV replication, cell entry and infection, and retroviral evolution. Here we combine cryoEM and cryoET to determine high-resolution in situ structures of the PFV icosahedral capsid (CA) and envelope glycoprotein (Env), including its type III transmembrane anchor and membrane-proximal external region (MPER), and show how they are organized in an integrated structure of assembled PFV particles. The atomic models reveal an ancient retroviral capsid architecture and an unexpected relationship between Env and other class 1 fusion proteins of the Mononegavirales. Our results represent the de novo structure determination of an assembled retrovirus particle.

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.

A universal design of restructured dimer antigens: Development of a superior vaccine against the paramyxovirus in transgenic rice.

The development of vaccines, which induce effective immune responses while ensuring safety and affordability, remains a substantial challenge. In this study, we proposed a vaccine model of a restructured "head-to-tail" dimer to efficiently stimulate B cell response. We also demonstrate the feasibility of using this model to develop a paramyxovirus vaccine through a low-cost rice endosperm expression system. Crystal structure and small-angle X-ray scattering data showed that the restructured hemagglutinin-neuraminidase (HN) formed tetramers with fully exposed quadruple receptor binding domains and neutralizing epitopes. In comparison with the original HN antigen and three traditional commercial whole virus vaccines, the restructured HN facilitated critical epitope exposure and initiated a faster and more potent immune response. Two-dose immunization with 0.5 µg of the restructured antigen (equivalent to one-127th of a rice grain) and one-dose with 5 µg completely protected chickens against a lethal challenge of the virus. These results demonstrate that the restructured HN from transgenic rice seeds is safe, effective, low-dose useful, and inexpensive. We provide a plant platform and a simple restructured model for highly effective vaccine development.

A three-way interface of the Nipah virus phosphoprotein X-domain coordinates polymerase movement along the viral genome.

Nipah virus (NiV) is a highly pathogenic paramyxovirus causing frequently lethal encephalitis in humans. The NiV genome is encapsidated by the nucleocapsid (N) protein. RNA synthesis is mediated by the viral RNA-dependent RNA polymerase (RdRP), consisting of the polymerase (L) protein complexed with the homo-tetrameric phosphoprotein (P). The advance of the polymerase along its template requires iterative dissolution and reformation of transient interactions between P and N protomers in a highly regulated process that remains poorly understood. This study applied functional and biochemical NiV polymerase assays to the problem. We mapped three distinct protein interfaces on the C-terminal P-X domain (P-XD), which form a triangular prism and engage L, the C-terminal N tail, and the globular N core, respectively. Transcomplementation assays using NiV L and N-tail binding-deficient mutants revealed that only one XD of a P tetramer binds to L, whereas three must be available for N-binding for efficient polymerase activity. The dissolution of the N-tail complex with P-XD was coordinated by a transient interaction between N-core and the α-1/2 face of this XD but not unoccupied XDs of the P tetramer, creating a timer for coordinated polymerase advance. IMPORTANCE: Mononegaviruses comprise major human pathogens such as the Ebola virus, rabies virus, respiratory syncytial virus, measles virus, and Nipah virus (NiV). For replication and transcription, their polymerase complexes must negotiate a protein-encapsidated RNA genome, which requires the highly coordinated continuous formation and resolution of protein-protein interfaces as the polymerase advances along the template. The viral P protein assumes a central role in this process, but the molecular mechanism of ensuring polymerase mobility is poorly understood. Studying NiV polymerase complexes, we applied functional and biochemical assays to map three distinct interfaces in the NiV P XD and identified transient interactions between XD and the nucleocapsid core as instrumental in coordinating polymerase advance. These results define a conserved molecular principle regulating paramyxovirus polymerase dynamics and illuminate a promising druggable target for the structure-guided development of broad-spectrum polymerase inhibitors.

Small hydrophobic (SH) proteins of Pneumoviridae and Paramyxoviridae: small but mighty.

Small hydrophobic (SH) proteins are a class of viral accessory proteins expressed by many members of the negative-stranded RNA viral families Paramyxoviridae and Pneumoviridae. Identified SH proteins are type I or II transmembrane (TM) proteins with a single-pass TM domain. Little is known about the functions of SH proteins; however, several possess viroporin activity, enhancing membrane permeability of infected cells or those expressing SH protein. Moreover, several SH proteins inhibit apoptosis and immune signaling pathways within infected cells, including TNF and interferon signaling, or activate inflammasomes. SH proteins are generally nonessential for viral replication in vitro, but loss of SH is often associated with reduced replication in vivo, suggesting a role in enhancing viral replication or evading host immunity. Analogous proteins are expressed by a variety of pathogens of public health importance; thus, understanding the functional importance and mechanisms of SH proteins provides insight into the pathogenesis and replication of negative-sense RNA viruses.

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.

How does the polymerase of non-segmented negative strand RNA viruses commit to transcription or genome replication?

The Mononegavirales, or non-segmented negative-sense RNA viruses (nsNSVs), includes significant human pathogens, such as respiratory syncytial virus, parainfluenza virus, measles virus, Ebola virus, and rabies virus. Although these viruses differ widely in their pathogenic properties, they are united by each having a genome consisting of a single strand of negative-sense RNA. Consistent with their shared genome structure, the nsNSVs have evolved similar ways to transcribe their genome into mRNAs and replicate it to produce new genomes. Importantly, both mRNA transcription and genome replication are performed by a single virus-encoded polymerase. A fundamental and intriguing question is: how does the nsNSV polymerase commit to being either an mRNA transcriptase or a replicase? The polymerase must become committed to one process or the other either before it interacts with the genome template or in its initial interactions with the promoter sequence at the 3´ end of the genomic RNA. This review examines the biochemical, molecular biology, and structural biology data regarding the first steps of transcription and RNA replication that have been gathered over several decades for different families of nsNSVs. These findings are discussed in relation to possible models that could explain how an nsNSV polymerase initiates and commits to either transcription or genome replication.

Prefusion stabilization of the Hendra and Langya virus F proteins.

Nipah virus (NiV) and Hendra virus (HeV) are pathogenic paramyxoviruses that cause mild-to-severe disease in humans. As members of the Henipavirus genus, NiV and HeV use an attachment (G) glycoprotein and a class I fusion (F) glycoprotein to invade host cells. The F protein rearranges from a metastable prefusion form to an extended postfusion form to facilitate host cell entry. Prefusion NiV F elicits higher neutralizing antibody titers than postfusion NiV F, indicating that stabilization of prefusion F may aid vaccine development. A combination of amino acid substitutions (L104C/I114C, L172F, and S191P) is known to stabilize NiV F in its prefusion conformation, although the extent to which substitutions transfer to other henipavirus F proteins is not known. Here, we perform biophysical and structural studies to investigate the mechanism of prefusion stabilization in F proteins from three henipaviruses: NiV, HeV, and Langya virus (LayV). Three known stabilizing substitutions from NiV F transfer to HeV F and exert similar structural and functional effects. One engineered disulfide bond, located near the fusion peptide, is sufficient to stabilize the prefusion conformations of both HeV F and LayV F. Although LayV F shares low overall sequence identity with NiV F and HeV F, the region around the fusion peptide exhibits high sequence conservation across all henipaviruses. Our findings indicate that substitutions targeting this site of conformational change might be applicable to prefusion stabilization of other henipavirus F proteins and support the use of NiV as a prototypical pathogen for henipavirus vaccine antigen design.IMPORTANCEPathogenic henipaviruses such as Nipah virus (NiV) and Hendra virus (HeV) cause respiratory symptoms, with severe cases resulting in encephalitis, seizures, and coma. The work described here shows that the NiV and HeV fusion (F) proteins share common structural features with the F protein from an emerging henipavirus, Langya virus (LayV). Sequence alignment alone was sufficient to predict which known prefusion-stabilizing amino acid substitutions from NiV F would stabilize the prefusion conformations of HeV F and LayV F. This work also reveals an unexpected oligomeric interface shared by prefusion HeV F and NiV F. Together, these advances lay a foundation for future antigen design targeting henipavirus F proteins. In this way, Nipah virus can serve as a prototypical pathogen for the development of protective vaccines and monoclonal antibodies to prepare for potential henipavirus outbreaks.

Tetracistronic minigenomes elucidate a functional promoter for Ghana virus and unveils Cedar virus replicase promiscuity for all henipaviruses.

Batborne henipaviruses, such as Nipah and Hendra viruses, 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 the Nipah, Hendra, and Cedar viruses, 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 driving replication and transcription of minigenomes from all tested henipaviruses. We also apply this technology to Ghana virus (GhV), an emergent species that 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. The use of our GhV system establishes the functionality of the GhV replicase and identifies two antivirals that are highly efficacious against the GhV polymerase. IMPORTANCE: Henipaviruses are recognized as significant global health threats due to their high mortality rates and lack of effective vaccines or therapeutics. Due to the requirement for high biocontainment facilities, the scope of research which may be conducted on henipaviruses is limited. To address this challenge, we developed innovative tetracistronic, transcription, and replication-competent minigenomes. We demonstrate that these systems replicate key aspects of the viral life cycle, such as budding, fusion, and receptor binding, and are safe for use in lower biocontainment settings. Importantly, the application of this system to the Ghana virus revealed that its known sequence is incomplete; however, substituting the missing sequences with those from other henipaviruses allowed us to overcome this challenge. We demonstrate that the Ghana virus replicative machinery is functional and can identify two orally efficacious antivirals effective against it. Our research offers a versatile system for life-cycle modeling of highly pathogenic henipaviruses at low biocontainment.

Nipah virus-associated neuropathology in African green monkeys during acute disease and convalescence.

BACKGROUND: Nipah virus is an emerging zoonotic virus that causes severe respiratory disease and meningoencephalitis. The pathophysiology of Nipah virus meningoencephalitis is poorly understood. METHODS: We have collected the brains of African green monkeys during multiple Nipah virus, Bangladesh studies, resulting in 14 brains with Nipah virus-associated lesions. RESULTS: The lesions seen in the brain of African green monkeys infected with Nipah virus, Bangladesh were very similar to those observed in humans with Nipah virus, Malaysia infection. We observed viral RNA and antigen within neurons and endothelial cells, within encephalitis foci and in uninflamed portions of the CNS. CD8+ T cells had a consistently high prevalence in CNS lesions. We developed a UNet model for quantifying and visualizing inflammation in the brain in a high-throughput and unbiased manner. While CD8+ T cells had a consistently high prevalence in CNS lesions, the model revealed that CD68+ cells were numerically the immune cell with the highest prevalence in the CNS of NiV-infected animals. CONCLUSION: Our study provides an in-depth analysis on Nipah virus infection in the brains of primates, and similarities between lesions in patients and the animals in our study validate this model.

Upper and/or Lower Respiratory Tract Infection Caused by Human Metapneumovirus After Allogeneic Hematopoietic Stem Cell Transplantation.

BACKGROUND: Human metapneumovirus (hMPV) epidemiology, clinical characteristics and risk factors for poor outcome after allogeneic stem cell transplantation (allo-HCT) remain a poorly investigated area. METHODS: This retrospective multicenter cohort study examined the epidemiology, clinical characteristics, and risk factors for poor outcomes associated with human metapneumovirus (hMPV) infections in recipients of allo-HCT. RESULTS: We included 428 allo-HCT recipients who developed 438 hMPV infection episodes between January 2012 and January 2019. Most recipients were adults (93%). hMPV infections were diagnosed at a median of 373 days after allo-HCT. The infections were categorized as upper respiratory tract disease (URTD) or lower respiratory tract disease (LRTD), with 60% and 40% of cases, respectively. Patients with hMPV LRTD experienced the infection earlier in the transplant course and had higher rates of lymphopenia, neutropenia, corticosteroid use, and ribavirin therapy. Multivariate analysis identified lymphopenia and corticosteroid use (>30 mg/d) as independent risk factors for LRTD occurrence. The overall mortality at day 30 after hMPV detection was 2% for URTD, 12% for possible LRTD, and 21% for proven LRTD. Lymphopenia was the only independent risk factor associated with day 30 mortality in LRTD cases. CONCLUSIONS: These findings highlight the significance of lymphopenia and corticosteroid use in the development and severity of hMPV infections after allo-HCT, with lymphopenia being a predictor of higher mortality in LRTD cases.

Structural basis of paramyxo- and pneumovirus polymerase inhibition by non-nucleoside small-molecule antivirals.

Small-molecule antivirals can be used as chemical probes to stabilize transitory conformational stages of viral target proteins, facilitating structural analyses. Here, we evaluate allosteric pneumo- and paramyxovirus polymerase inhibitors that have the potential to serve as chemical probes and aid the structural characterization of short-lived intermediate conformations of the polymerase complex. Of multiple inhibitor classes evaluated, we discuss in-depth distinct scaffolds that were selected based on well-understood structure-activity relationships, insight into resistance profiles, biochemical characterization of the mechanism of action, and photoaffinity-based target mapping. Each class is thought to block structural rearrangements of polymerase domains albeit target sites and docking poses are distinct. This review highlights validated druggable targets in the paramyxo- and pneumovirus polymerase proteins and discusses discrete structural stages of the polymerase complexes required for bioactivity.

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.

Structures of Langya Virus Fusion Protein Ectodomain in Pre- and Postfusion Conformation.

Langya virus (LayV) is a paramyxovirus in the Henipavirus genus, closely related to the deadly Nipah (NiV) and Hendra (HeV) viruses, that was identified in August 2022 through disease surveillance following animal exposure in eastern China. Paramyxoviruses present two glycoproteins on their surface, known as attachment and fusion proteins, that mediate entry into cells and constitute the primary antigenic targets for immune response. Here, we determine cryo-electron microscopy (cryo-EM) structures of the uncleaved LayV fusion protein (F) ectodomain in pre- and postfusion conformations. The LayV-F protein exhibits pre- and postfusion architectures that, despite being highly conserved across paramyxoviruses, show differences in their surface properties, in particular at the apex of the prefusion trimer, that may contribute to antigenic variability. While dramatic conformational changes were visualized between the pre- and postfusion forms of the LayV-F protein, several domains remained invariant, held together by highly conserved disulfides. The LayV-F fusion peptide (FP) is buried within a highly conserved, hydrophobic interprotomer pocket in the prefusion state and is notably less flexible than the rest of the protein, highlighting its "spring-loaded" state and suggesting that the mechanism of pre-to-post transition must involve perturbations to the pocket and release of the fusion peptide. Together, these results offer a structural basis for how the Langya virus fusion protein compares to its Henipavirus relatives and propose a mechanism for the initial step of pre- to postfusion conversion that may apply more broadly to paramyxoviruses. IMPORTANCE The Henipavirus genus is quickly expanding into new animal hosts and geographic locations. This study compares the structure and antigenicity of the Langya virus fusion protein to other henipaviruses, which have important vaccine and therapeutic development implications. Furthermore, the study proposes a new mechanism to explain the early steps of the fusion initiation process that can be more broadly applied to the Paramyxoviridae family.

Discovery and characterization of novel jeilongviruses in wild rodents from Hubei, China.

The genus Jeilongvirus comprises non-segmented negative-stranded RNA viruses that are classified within the Paramyxoviridae family by phylogeny. Jeilongviruses are found in various reservoirs, including rodents and bats. Rodents are typical viral reservoirs with diverse spectra and zoonotic potential. Little is currently known about jeilongviruses in rodents from central China. The study utilized high-throughput and Sanger sequencing to obtain jeilongvirus genomes, including those of two novel strains (HBJZ120/CHN/2021 (17,468 nt) and HBJZ157/CHN/2021 (19,143 nt)) and three known viruses (HBXN18/CHN/2021 (19,212 nt), HBJZ10/CHN/2021 (19,700 nt), HBJM106/CHN/2021 (18,871 nt)), which were characterized by genome structure, identity matrix, and phylogenetic analysis. Jeilongviruses were classified into three subclades based on their topology, phylogeny, and hosts. Based on the amino acid sequence identities and phylogenetic analysis of the L protein, HBJZ120/CHN/2021 and HBJZ157/CHN/2021 were found to be strains rather than novel species. Additionally, according to specific polymerase chain reaction screening, the positive percentage of Beilong virus in Hubei was 6.38%, suggesting that Beilong virus, belonging to the Jeilongvirus genus, is likely to be widespread in wild rodents. The identification of novel strains further elucidated the genomic diversity of jeilongviruses. Additionally, the prevalence of jeilongviruses in Hubei, China, was profiled, establishing a foundation for the surveillance and early warning of emerging paramyxoviruses.

Epidemiology of human metapneumovirus in Taiwan from 2013 to 2023.

Human metapneumovirus (HMPV) is a member of the genus Metapneumovirus in the family Pneumoviridae of the order Mononegavirales that can cause upper and lower respiratory tract disease. This retrospective study describes the epidemiology of hMPV based on community viral surveillance results from sentinel sites across Taiwan from 2013 to 2023. A total of 114 hMPV strains were isolated and analyzed to assess viral evolution through sequencing of their fusion protein genes. This study revealed that hMPV cases occur almost year-round in Taiwan, with a peak occurring during spring (March to May). Of the 114 infected patients, 68.4% were children under 4 years old. The geographical distribution of hMPV positivity was highest in Penghu County, followed by Changhua County and Hsinchu County. The clinical symptoms of hMPV infection are nonspecific, with fever (56.1%), cough (44.7%), rhinorrhea (21.1%), and sore throat (14.9%) being the most common. However, a few patients also developed severe central nervous system symptoms (1.8%) or dyspnea (0.9%). Phylogenetic analysis revealed genetic diversity among the 114 isolated hMPV strains, with the A2 lineage (57.9%) being the most frequently observed, followed by the B2 lineage (33.3%), in the Taiwanese community from 2013 to 2023. In conclusion, hMPV causes a serious acute respiratory disease in Taiwan that should not be neglected. Further epidemiological surveillance and investigations of the clinical characteristics of hMPV should be performed continually for prevention and control of this virus.

Oreoch-1: A broad-spectrum virus and host-targeting peptide against animal infections.

In recent decades, the global rise of viral emerging infectious diseases has posed a substantial threat to both human and animal health worldwide. The rapid spread and accumulation of mutations into viruses, and the limited availability of antiviral drugs and vaccines, stress the urgent need for alternative therapeutic strategies. Antimicrobial peptides (AMPs) derived from natural sources present a promising avenue due to their specificity and effectiveness against a broad spectrum of pathogens. The present study focuses on investigating the antiviral potential of oreochromicin-1 (oreoch-1), a fish-derived AMP obtained from Nile tilapia, against a wide panel of animal viruses including canine distemper virus (CDV), Schmallenberg virus (SBV), caprine herpesvirus 1 (CpHV-1), and bovine herpesvirus 1 (BoHV-1). Oreoch-1 exhibited a strong antiviral effect, demonstrating an inhibition of infection at concentrations in the micromolar range. The mechanism of action involves the interference with viral entry into host cells and a direct interaction between oreoch-1 and the viral envelope. In addition, we observed that the peptide could also interact with the cell during the CDV infection. These findings not only highlight the efficacy of oreoch-1 in inhibiting viral infection but also emphasize the potential of fish-derived peptides, specifically oreoch-1, as effective antiviral agents against viral infections affecting animals, whose potential to spill into humans is high. This research contributes valuable insights to the ongoing quest for novel antiviral drugs with the potential to mitigate the impact of infectious diseases on a global scale.

Evaluation of the sensitivity of a measles diagnostic real-time RT-PCR assay incorporating recently observed priming mismatch variants, 2024.

We investigated a variant of measles virus that encodes three mismatches to the reverse priming site for a widely used diagnostic real-time RT-PCR assay; reduction of sensitivity was hypothesised. We examined performance of the assay in context of the variant using in silico data, synthetic RNA templates and clinical specimens. Sensitivity was reduced observed at low copy numbers for templates encoding the variant sequence. We designed and tested an alternate priming strategy, rescuing the sensitivity of the assay.

Paramyxoviruses: Pathogenesis, Vaccines, Antivirals, and Prototypes for Pandemic Preparedness.

The Paramyxoviridae family includes established human pathogens such as measles virus, mumps virus, and the human parainfluenza viruses; highly lethal zoonotic pathogens such as Nipah virus; and a number of recently identified agents, such as Sosuga virus, which remain poorly understood. The high human-to-human transmission rate of paramyxoviruses such as measles virus, high case fatality rate associated with other family members such as Nipah virus, and the existence of poorly characterized zoonotic pathogens raise concern that known and unknown paramyxoviruses have significant pandemic potential. In this review, the general life cycle, taxonomic relationships, and viral pathogenesis are described for paramyxoviruses that cause both systemic and respiratory system-restricted infections. Next, key gaps in critical areas are presented, following detailed conversations with subject matter experts and based on the current literature. Finally, we present an assessment of potential prototype pathogen candidates that could be used as models to study this important virus family, including assessment of the strengths and weaknesses of each potential prototype.

Fatal Human Neurologic Infection Caused by Pigeon Avian Paramyxovirus-1, Australia.

Avian paramyxovirus type 1 (APMV-1) is a virus of birds that results in a range of outcomes, from asymptomatic infections to outbreaks of systemic respiratory and neurologic disease, depending on the virus strain and the avian species affected. Humans are rarely affected; those who are predominantly experience mild conjunctivitis. We report a fatal case of neurologic disease in a 2-year-old immunocompromised child in Australia. Metagenomic sequencing and histopathology identified the causative agent as the pigeon variant of APMV-1. This diagnosis should be considered in neurologic conditions of undefined etiologies. Agnostic metagenomic sequencing methods are useful in such settings to direct diagnostic and therapeutic efforts.