-
Antiviral Research May 2017Filoviruses are important pathogens that cause severe and often fatal hemorrhagic fever in humans, for which no approved vaccines and antiviral treatments are yet... (Review)
Review
Filoviruses are important pathogens that cause severe and often fatal hemorrhagic fever in humans, for which no approved vaccines and antiviral treatments are yet available. In an earlier article (Martin et al., Antiviral Research, 2016), we reviewed the role of the filovirus surface glycoprotein in replication and as a target for drugs and vaccines. In this review, we focus on recent findings on the filovirus replication machinery and how they could be used for the identification of new therapeutic targets and the development of new antiviral compounds. First, we summarize the recent structural and functional advances on the molecules involved in filovirus replication/transcription cycle, particularly the NP, VP30, VP35 proteins, and the "large" protein L, which harbors the RNA-dependent RNA polymerase (RdRp) and mRNA capping activities. These proteins are essential for viral mRNA synthesis and genome replication, and consequently they constitute attractive targets for drug design. We then describe how these insights into filovirus replication mechanisms and the structure/function characterization of the involved proteins have led to the development of new and innovative antiviral strategies that may help reduce the filovirus disease case fatality rate through post-exposure or prophylactic treatments.
Topics: Antiviral Agents; Drug Design; Drug Discovery; Ebolavirus; Filoviridae; Filoviridae Infections; Marburgvirus; RNA-Dependent RNA Polymerase; Transcription Factors; Viral Proteins; Viral Regulatory and Accessory Proteins; Virus Replication
PubMed: 28192094
DOI: 10.1016/j.antiviral.2017.02.004 -
Biotechnology & Genetic Engineering... Apr 2018The family Rhabdoviridae (RV) comprises a large, genetically diverse collection of single-stranded, negative sense RNA viruses from the order Mononegavirales. Several RV... (Review)
Review
The family Rhabdoviridae (RV) comprises a large, genetically diverse collection of single-stranded, negative sense RNA viruses from the order Mononegavirales. Several RV members are being developed as live-attenuated vaccine vectors for the prevention or treatment of infectious disease and cancer. These include the prototype recombinant Vesicular Stomatitis Virus (rVSV) and the more recently developed recombinant Maraba Virus, both species within the genus Vesiculoviridae. A relatively strong safety profile in humans, robust immunogenicity and genetic malleability are key features that make the RV family attractive vaccine platforms. Currently, the rVSV vector is in preclinical development for vaccination against numerous high-priority infectious diseases, with clinical evaluation underway for HIV/AIDS and Ebola virus disease. Indeed, the success of the rVSV-ZEBOV vaccine during the 2014-15 Ebola virus outbreak in West Africa highlights the therapeutic potential of rVSV as a vaccine vector for acute, life-threatening viral illnesses. The rVSV and rMaraba platforms are also being tested as 'oncolytic' cancer vaccines in a series of phase 1-2 clinical trials, after being proven effective at eliciting immune-mediated tumour regression in preclinical mouse models. In this review, we discuss the biological and genetic features that make RVs attractive vaccine platforms and the development and ongoing testing of rVSV and rMaraba strains as vaccine vectors for infectious disease and cancer.
Topics: Animals; Clinical Trials as Topic; Communicable Disease Control; Communicable Diseases; Genetic Vectors; Humans; Neoplasms; Oncolytic Viruses; Rhabdoviridae; Vaccines, Attenuated
PubMed: 29781359
DOI: 10.1080/02648725.2018.1474320 -
Journal of Virology Feb 2024Nipah virus (NiV) and Hendra virus (HeV) are pathogenic paramyxoviruses that cause mild-to-severe disease in humans. As members of the genus, NiV and HeV use an...
Nipah virus (NiV) and Hendra virus (HeV) are pathogenic paramyxoviruses that cause mild-to-severe disease in humans. As members of the 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.
Topics: Humans; Glycoproteins; Hendra Virus; Henipavirus; Henipavirus Infections; Nipah Virus; Peptides; Viral Fusion Proteins; Viral Proteins
PubMed: 38214525
DOI: 10.1128/jvi.01372-23 -
The Journal of Infectious Diseases Nov 2023Vesicular stomatitis virus-Ebola virus (VSV-EBOV) vaccine has been successfully used in ring vaccination approaches during EBOV disease outbreaks demonstrating its...
Vesicular stomatitis virus-Ebola virus (VSV-EBOV) vaccine has been successfully used in ring vaccination approaches during EBOV disease outbreaks demonstrating its general benefit in short-term prophylactic vaccination, but actual proof of its benefit in true postexposure prophylaxis (PEP) for humans is missing. Animal studies have indicated PEP efficacy when VSV-EBOV was used within hours of lethal EBOV challenge. Here, we used a lower EBOV challenge dose and a combined intravenous and intramuscular VSV-EBOV administration to improve PEP efficacy in the rhesus macaque model. VSV-EBOV treatment 1 hour after EBOV challenge resulted in delayed disease progression but little benefit in outcome. Thus, we could not confirm previous results indicating questionable benefit of VSV-EBOV for EBOV PEP in a nonhuman primate model.
Topics: Humans; Animals; Ebolavirus; Macaca mulatta; Hemorrhagic Fever, Ebola; Vesiculovirus; Vesicular stomatitis Indiana virus; Ebola Vaccines
PubMed: 37474155
DOI: 10.1093/infdis/jiad280 -
Vaccine Jan 2017Despite the recent explosion in RSV vaccine development, there remain substantial hurdles to overcome before licensing of effective vaccines will allow widespread use,... (Review)
Review
Despite the recent explosion in RSV vaccine development, there remain substantial hurdles to overcome before licensing of effective vaccines will allow widespread use, particularly in high-risk populations. Incomplete understanding of mechanisms and correlates of protection against RSV mean that, for the time being, successful RSV vaccines must directly demonstrate efficacy, which necessitates large and costly clinical trials in naturally infected patients. To mitigate the risks inherent in progressing to these late-stage trials, experimental human RSV infection studies have recently been re-established, representing the interface between pre-clinical models and observational studies of patients. Not only can they be used for early proof-of-concept clinical trials to test vaccine efficacy, but human challenge studies also offer the potential to better understand protective immunity against RSV infection to improve vaccine design and delivery. In the past, controlled human infection studies with RSV have been instrumental in elucidating the influence of factors such as route of infection and type of inoculum on the course of disease. Recently, efficacy trials of novel RSV antiviral drugs have also been successfully undertaken. Now, with advances in technology, detailed investigations of human mucosal immunity in the RSV-infected airway are possible. These have indicated defects in RSV-induced humoral and CD8+ T cell immunity that may contribute to the recurrent symptomatic infection that occurs throughout life and should be circumvented by optimal vaccines. Here, we discuss the insights derived from RSV human challenge models; the major impediments to their more widespread uptake; and their potential benefit in accelerating vaccine development, including future directions to further enhance the relevance of these models to at-risk patient populations.
Topics: Host-Pathogen Interactions; Human Experimentation; Humans; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human
PubMed: 27889256
DOI: 10.1016/j.vaccine.2016.08.086 -
Viruses Oct 2022Borna disease virus 1 (BoDV-1) is a neurotropic RNA virus belonging to the family within the order . Whereas BoDV-1 causes neurological and behavioral disorders, called... (Review)
Review
Borna disease virus 1 (BoDV-1) is a neurotropic RNA virus belonging to the family within the order . Whereas BoDV-1 causes neurological and behavioral disorders, called Borna disease (BD), in a wide range of mammals, its virulence in humans has been debated for several decades. However, a series of case reports in recent years have established the nature of BoDV-1 as a zoonotic pathogen that causes fatal encephalitis in humans. Although many virological properties of BoDV-1 have been revealed to date, the mechanism by which it causes fatal encephalitis in humans remains unclear. In addition, there are no effective vaccines or antiviral drugs that can be used in clinical practice. A reverse genetics approach to generating replication-competent recombinant viruses from full-length cDNA clones is a powerful tool that can be used to not only understand viral properties but also to develop vaccines and antiviral drugs. The rescue of recombinant BoDV-1 (rBoDV-1) was first reported in 2005. However, due to the slow nature of the replication of this virus, the rescue of high-titer rBoDV-1 required several months, limiting the use of this system. This review summarizes the history of the reverse genetics and artificial replication systems for orthobornaviruses and explores the recent progress in efforts to rescue rBoDV-1.
Topics: Animals; Humans; Borna disease virus; DNA, Complementary; Reverse Genetics; Virus Replication; Antiviral Agents; Encephalitis; Mammals
PubMed: 36298790
DOI: 10.3390/v14102236 -
Communications Biology Jun 2023Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in...
Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in infants, elderly, and immunocompromised adults. Therapeutic small molecule inhibitors that bind to the RSV polymerase and inhibit viral replication are being developed, but their binding sites and molecular mechanisms of action remain largely unknown. Here we report a conserved allosteric inhibitory site identified on the L polymerase proteins of RSV and HMPV that can be targeted by a dual-specificity, non-nucleoside inhibitor, termed MRK-1. Cryo-EM structures of the inhibitor in complexes with truncated RSV and full-length HMPV polymerase proteins provide a structural understanding of how MRK-1 is active against both viruses. Functional analyses indicate that MRK-1 inhibits conformational changes necessary for the polymerase to engage in RNA synthesis initiation and to transition into an elongation mode. Competition studies reveal that the MRK-1 binding pocket is distinct from that of a capping inhibitor with an overlapping resistance profile, suggesting that the polymerase conformation bound by MRK-1 may be distinct from that involved in mRNA capping. These findings should facilitate optimization of dual RSV and HMPV replication inhibitors and provide insights into the molecular mechanisms underlying their polymerase activities.
Topics: Infant; Adult; Humans; Aged; Metapneumovirus; RNA-Dependent RNA Polymerase; Respiratory Syncytial Virus, Human; Respiratory Tract Infections; RNA, Messenger
PubMed: 37337079
DOI: 10.1038/s42003-023-04990-0 -
Viruses Aug 2020Rhabdoviruses, as single-stranded, negative-sense RNA viruses within the order , are characterised by bullet-shaped or bacteroid particles that contain a helical... (Review)
Review
Rhabdoviruses, as single-stranded, negative-sense RNA viruses within the order , are characterised by bullet-shaped or bacteroid particles that contain a helical ribonucleoprotein complex (RNP). Here, we review the components of the RNP and its higher-order structural assembly.
Topics: Nucleocapsid Proteins; Protein Conformation; Rhabdoviridae; Ribonucleoproteins; Viral Matrix Proteins; Viral Proteins; Viral Replicase Complex Proteins; Virion
PubMed: 32872471
DOI: 10.3390/v12090959 -
Archives of Virology Aug 2018In 2018, the order Mononegavirales was expanded by inclusion of 1 new genus and 12 novel species. This article presents the updated taxonomy of the order Mononegavirales...
In 2018, the order Mononegavirales was expanded by inclusion of 1 new genus and 12 novel species. This article presents the updated taxonomy of the order Mononegavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.
Topics: Animals; Humans; Mononegavirales; Mononegavirales Infections; Phylogeny
PubMed: 29637429
DOI: 10.1007/s00705-018-3814-x -
Viruses Jun 2019Canine distemper virus (CDV) is a worldwide distributed virus which belongs to the genus within the family. CDV spreads through the lymphatic, epithelial, and nervous... (Review)
Review
Canine distemper virus (CDV) is a worldwide distributed virus which belongs to the genus within the family. CDV spreads through the lymphatic, epithelial, and nervous systems of domestic dogs and wildlife, in at least six orders and over 20 families of mammals. Due to the high morbidity and mortality rates and broad host range, understanding the epidemiology of CDV is not only important for its control in domestic animals, but also for the development of reliable wildlife conservation strategies. The present review aims to give an outlook of the multiple evolutionary landscapes and factors involved in the transmission of CDV by including epidemiological data from multiple species in urban, wild and peri-urban settings, not only in domestic animal populations but at the wildlife interface. It is clear that different epidemiological scenarios can lead to the presence of CDV in wildlife even in the absence of infection in domestic populations, highlighting the role of CDV in different domestic or wild species without clinical signs of disease mainly acting as reservoirs (peridomestic and mesocarnivores) that are often found in peridomestic habits triggering CDV epidemics. Another scenario is driven by mutations, which generate genetic variation on which random drift and natural selection can act, shaping the genetic structure of CDV populations leading to some fitness compensations between hosts and driving the evolution of specialist and generalist traits in CDV populations. In this scenario, the highly variable protein hemagglutinin (H) determines the cellular and host tropism by binding to signaling lymphocytic activation molecule (SLAM) and nectin-4 receptors of the host; however, the multiple evolutionary events that may have facilitated CDV adaptation to different hosts must be evaluated by complete genome sequencing. This review is focused on the study of CDV interspecies transmission by examining molecular and epidemiological reports based on sequences of the hemagglutinin gene and the growing body of studies of the complete genome; emphasizing the importance of long-term multidisciplinary research that tracks CDV in the presence or absence of clinical signs in wild species, and helping to implement strategies to mitigate the infection. Integrated research incorporating the experience of wildlife managers, behavioral and conservation biologists, veterinarians, virologists, and immunologists (among other scientific areas) and the inclusion of several wild and domestic species is essential for understanding the intricate epidemiological dynamics of CDV in its multiple host infections.
Topics: Animals; Animals, Wild; Distemper; Distemper Virus, Canine; Dogs; Evolution, Molecular; Host Specificity; Phylogeny
PubMed: 31247987
DOI: 10.3390/v11070582