Hendra and Nipah infection: emerging paramyxoviruses

Enzyme-Linked Immunosorbent Assay Using Henipavirus-Receptor EphrinB2 and Monoclonal Antibodies for Detecting Nipah and Hendra Viruses

The Nipah virus (NiV) and the Hendra virus (HeV) are highly pathogenic zoonotic diseases that can cause fatal infections in humans and animals. Early detection is critical for the control of NiV and HeV infections. We present the development of two antigen-detection ELISAs (AgELISAs) using the henipavirus-receptor EphrinB2 and monoclonal antibodies (mAbs) to detect NiV and HeV. The NiV AgELISA detected only NiV, whereas the NiV/HeV AgELISA detected both NiV and HeV. The diagnostic specificities of the NiV AgELISA and the NiV/HeV AgELISA were 100% and 97.8%, respectively. Both assays were specific for henipaviruses and showed no cross-reactivity with other viruses. The AgELISAs detected NiV antigen in experimental pig nasal wash samples taken at 4 days post-infection. With the combination of both AgELISAs, NiV can be differentiated from HeV. Complementing other henipavirus detection methods, these two newly developed AgELISAs can rapidly detect NiV and HeV in a large number of samples and are suitable for use in remote areas where other tests are not available.

Pangenomic and immunoinformatics based analysis of Nipah virus revealed CD4+ and CD8+ T-Cell epitopes as potential vaccine candidates

Introduction: Nipah (NiV) is the zoonotic deadly bat-borne virus that causes neurological and respiratory infections which ultimately lead to death. There are 706 infected cases reported up till now especially in Asia, out of which 409 patients died. There is no vaccine and effective treatment available for NiV infections and we have to timely design such strategies as world could not bear another pandemic situation. Methods: In this study, we screened viral proteins of NiV strains based on pangenomics analysis, antigenicity, molecular weight, and sub-cellular localization. The immunoproteomics based approach was used to predict T-cell epitopes of MHC class-I and II as potential vaccine candidates. These epitopes are capable to activate CD4+, CD8+, and T-cell dependent B-lymphocytes. Results: The two surface proteins including fusion glycoprotein (F) and attachment glycoprotein (G) are antigenic with molecular weights of 60 kDa and 67 kDa respectively. Three epitopes of F protein (VNYNSEGIA, PNFILVRNT, and IKMIPNVSN) were ranked and selected based on the binding affinity with MHC class-I, and 3 epitopes (VILNKRYYS, ILVRNTLIS, and VKLQETAEK) with MHC-II molecules. Similarly, for G protein, 3 epitopes each for MHC-I (GKYDKVMPY, ILKPKLISY, and KNKIWCISL) and MHC-II (LRNIEKGKY, FLIDRINWI, and FLLKNKIWC) with substantial binding energies were predicted. Based on the physicochemical properties, all these epitopes are non-toxic, hydrophilic, and stable. Conclusion: Our vaccinomics and system-level investigation could help to trigger the host immune system to prevent NiV infection.

A Novel DNAzyme-Based Fluorescent Biosensor for Detection of RNA-Containing Nipah Henipavirus

Nipah virus (NiV) is a zoonotic RNA virus which infects humans and animals in Asian countries. Infection in humans occurs in different forms, from asymptomatic infection to fatal encephalitis, and death occurred in 40-70% of those infected in outbreaks that occurred between 1998 and 2018. Modern diagnostics is carried out by real-time PCR to identify pathogens or by ELISA to detect antibodies. Both technologies are labor-intensive and require the use of expensive stationary equipment. Thus, there is a need to develop alternative simple, fast and accurate test systems for virus detection. The aim of this study was to develop a highly specific and easily standardized system for the detection of Nipah virus RNA. In our work, we have developed a design for a Dz_NiV biosensor based on a split catalytic core of deoxyribozyme 10-23. It was shown that the assembly of active 10-23 DNAzymes occurred only in the presence of synthetic target Nipah virus RNA and that this was accompanied by stable fluorescence signals from the cleaved fluorescent substrates. This process was realized at 37 °C, pH 7.5, and in the presence of magnesium ions, with a 10 nM limit of detection achieved for the synthetic target RNA. Constructed via a simple and easily modifiable process, our biosensor may be used for the detection of other RNA viruses.

Detection of Nipah and Hendra Viruses Using Recombinant Human Ephrin B2 Capture Virus in Immunoassays

Nipah virus (NiV) and Hendra virus (HeV) are classified as high-consequence zoonotic viruses characterized by high pathogenicity and high mortality in animals and humans. Rapid diagnosis is essential to containing the outbreak. In this study, the henipavirus receptor ephrin B2 was examined to determine whether it could be used as a universal ligand for henipavirus detection in immunoassays. Enzyme-linked immunosorbent assays (ELISAs) were developed using recombinant ephrin B2 as the capture ligand and two monoclonal antibodies (mAbs) as detection reagents. Using mAb F27NiV-34, which cross-reacts with NiV and HeV, we were able to detect NiV and HeV, while mAb F20NiV-65 was used to detect NiV. Therefore, using these two ELISAs, we were able to differentiate between NiV and HeV. Furthermore, we developed a rapid lateral flow strip test for NiV detection using ephrin B2 as the capture ligand combined with mAb F20NiV-65 as the detector. Taken together, our results show that the combination of ephrin B2 and a specific mAb provides an excellent pairing for NiV and HeV detection.

Anticipation of Antigenic Sites for the Goal of Vaccine Designing Against Nipah Virus: An Immunoinformatics Inquisitive Quest

With time, the Nipah virus has been proved as a fatal and dangerous pathogen for humanity. Nipah virus has its origin from bats and severely affects the respiratory as well as neurological organs. Regular outbreaks and unavailability of proper treatment for Nipah virus infection, demands the designing of vaccine for this disease. This prediction study was conducted to explore B cell epitopes from the Nipah virus’s proteome using the immunoinformatics approach. In this curious quest of anticipation of antigenic sites for the Insilico peptide vaccine for the Nipah virus, nine NV-B strain proteins were retrieved for further series of investigations. After sequential refining through immunoinformatics approaches, a total of 26 epitopes was selected to perform molecular modeling and docking. PEPstrMOD and Swiss model, respectively performed 3D modeling of epitopes with their respective alleles. Based on minimum binding energy, four epitopes viz. LHLGNFVRR, LNLSPLIQR, YHNMSPINR and FRRNNAIAF were predicted as promiscuous B cell epitopes. Based on low binding affinity and high population coverage worldwide, epitope LHLGNFVRR was finally selected. Increased Stability of the LHLGNFVRR- HLA DRB_1301 complex during simulation studies exhibit it as the most promising vaccine bidder. So complex of LHLGNFVRR- HLA DRB_1301 has shown most significance result for vaccine and for further validation and confirmation, wet lab and clinical trials can provide the potential of predicted peptides for the subunit vaccine.

Zoonotic potential of Newcastle disease virus: Old and novel perspectives related to public health

Newcastle disease virus (NDV) has a worldwide distribution, causing lethal infection in a wide range of avian species. Affected birds develop respiratory, digestive and neurologic symptoms with profound immunosuppression. Mild systemic Newcastle disease (ND) infection restricted to the respiratory and neurological systems can be observed in humans and other non-avian hosts. Evidence of ND infection and its genome-based detection have been reported in Bovidae (cattle and sheep), Mustelidae (mink), Cercetidae (hamster), Muridae (mice), Leporidae (rabbit), Camelidae (camel), Suidae (pig), Cercophithecidae (monkeys) and Hominidae (humans). Owing to frequent ND outbreaks in poultry workers, individuals engaged in the veterinary field, including poultry production or evisceration and vaccine production units have constantly been at a much higher risk than the general population. A lethal form of infection has been described in immunocompromised humans and non-avian species including mink, pig and cattle demonstrating the capability of NDV to cross species barriers. Therefore, contact with infectious material and/or affected birds can pose a risk of zoonosis and raise public health concerns. The broad and expanding host range of NDV and its maintenance within non-avian species hampers disease control, particularly in disease-endemic settings.

Neurologic Manifestations of the World Health Organization's List of Pandemic and Epidemic Diseases

The World Health Organization (WHO) monitors the spread of diseases globally and maintains a list of diseases with epidemic or pandemic potential. Currently listed diseases include Chikungunya, cholera, Crimean-Congo hemorrhagic fever, Ebola virus disease, Hendra virus infection, influenza, Lassa fever, Marburg virus disease, Neisseria meningitis, MERS-CoV, monkeypox, Nipah virus infection, novel coronavirus (COVID-19), plague, Rift Valley fever, SARS, smallpox, tularemia, yellow fever, and Zika virus disease. The associated pathogens are increasingly important on the global stage. The majority of these diseases have neurological manifestations. Those with less frequent neurological manifestations may also have important consequences. This is highlighted now in particular through the ongoing COVID-19 pandemic and reinforces that pathogens with the potential to spread rapidly and widely, in spite of concerted global efforts, may affect the nervous system. We searched the scientific literature, dating from 1934 to August 2020, to compile data on the cause, epidemiology, clinical presentation, neuroimaging features, and treatment of each of the diseases of epidemic or pandemic potential as viewed through a neurologist's lens. We included articles with an abstract or full text in English in this topical and scoping review. Diseases with epidemic and pandemic potential can be spread directly from human to human, animal to human, via mosquitoes or other insects, or via environmental contamination. Manifestations include central neurologic conditions (meningitis, encephalitis, intraparenchymal hemorrhage, seizures), peripheral and cranial nerve syndromes (sensory neuropathy, sensorineural hearing loss, ophthalmoplegia), post-infectious syndromes (acute inflammatory polyneuropathy), and congenital syndromes (fetal microcephaly), among others. Some diseases have not been well-characterized from a neurological standpoint, but all have at least scattered case reports of neurological features. Some of the diseases have curative treatments available while in other cases, supportive care remains the only management option. Regardless of the pathogen, prompt, and aggressive measures to control the spread of these agents are the most important factors in lowering the overall morbidity and mortality they can cause.

Human Paramyxovirus Infections Induce T Cells That Cross-React with Zoonotic Henipaviruses

Humans are infected with paramyxoviruses of different genera early in life, which induce cytotoxic T cells that may recognize conserved epitopes. This raises the question of whether cross-reactive T cells induced by antecedent paramyxovirus infections provide partial protection against highly lethal zoonotic Nipah virus infections. By characterizing a measles virus-specific but paramyxovirus cross-reactive human T cell clone, we discovered a highly conserved HLA-B*1501-restricted T cell epitope in the fusion protein. Using peptides, tetramers, and single cell sorting, we isolated a parainfluenza virus-specific T cell clone from a healthy adult and showed that both clones cleared Nipah virus-infected cells. We identified multiple conserved hot spots in paramyxovirus proteomes that contain other potentially cross-reactive epitopes. Our data suggest that, depending on HLA haplotype and history of paramyxovirus exposures, humans may have cross-reactive T cells that provide protection against Nipah virus. The effect of preferential boosting of these cross-reactive epitopes needs to be further studied in light of paramyxovirus vaccination studies.IMPORTANCE Humans encounter multiple paramyxoviruses early in life. This study shows that infection with common paramyxoviruses can induce T cells cross-reactive with the highly pathogenic Nipah virus. This demonstrates that the combination of paramyxovirus infection history and HLA haplotype affects immunity to phylogenetically related zoonotic paramyxoviruses.

Nipah Virus: Past Outbreaks and Future Containment

Viral outbreaks of varying frequencies and severities have caused panic and havoc across the globe throughout history. Influenza, small pox, measles, and yellow fever reverberated for centuries, causing huge burden for economies. The twenty-first century witnessed the most pathogenic and contagious virus outbreaks of zoonotic origin including severe acute respiratory syndrome coronavirus (SARS-CoV), Ebola virus, Middle East respiratory syndrome coronavirus (MERS-CoV) and Nipah virus. Nipah is considered one of the world’s deadliest viruses with the heaviest mortality rates in some instances. It is known to cause encephalitis, with cases of acute respiratory distress turning fatal. Various factors contribute to the onset and spread of the virus. All through the infected zone, various strategies to tackle and enhance the surveillance and awareness with greater emphasis on personal hygiene has been formulated. This review discusses the recent outbreaks of Nipah virus in Malaysia, Bangladesh and India, the routes of transmission, prevention and control measures employed along with possible reasons behind the outbreaks, and the precautionary measures to be ensured by private–public undertakings to contain and ensure a lower incidence in the future.

Anticancer activity of metformin: a systematic review of the literature

Background

The anticancer activity of metformin has been confirmed against several cancer types in vitro and in vivo. However, the underlying mechanisms of metformin in the treatment of cancer are not fully understood. This systematic review aims to discuss the possible anticancer mechanism of action of metformin.

Method

A search through different databases was conducted, including Medline and EMBASE.

Results

A total of 96 articles were identified of which 56 were removed for duplication and 24 were excluded after reviewing the title and abstract. A total of 12 research articles were included that describe different antiproliferative mechanisms that may contribute to the antineoplastic effects of metformin.

Conclusion

This analysis discussed the potential anticancer activity of metformin and highlighted the importance of AMPK as a potential target for anticancer therapy.

Nipah virus: epidemiology, pathology, immunobiology and advances in diagnosis, vaccine designing and control strategies - a comprehensive review

Nipah (Nee-pa) viral disease is a zoonotic infection caused by Nipah virus (NiV), a paramyxovirus belonging to the genus Henipavirus of the family Paramyxoviridae. It is a biosafety level-4 pathogen, which is transmitted by specific types of fruit bats, mainly Pteropus spp. which are natural reservoir host. The disease was reported for the first time from the Kampung Sungai Nipah village of Malaysia in 1998. Human-to-human transmission also occurs. Outbreaks have been reported also from other countries in South and Southeast Asia. Phylogenetic analysis affirmed the circulation of two major clades of NiV as based on currently available complete N and G gene sequences. NiV isolates from Malaysia and Cambodia clustered together in NiV-MY clade, whereas isolates from Bangladesh and India clusterered within NiV-BD clade. NiV isolates from Thailand harboured mixed population of sequences. In humans, the virus is responsible for causing rapidly progressing severe illness which might be characterized by severe respiratory illness and/or deadly encephalitis. In pigs below six months of age, respiratory illness along with nervous symptoms may develop. Different types of enzyme-linked immunosorbent assays along with molecular methods based on polymerase chain reaction have been developed for diagnostic purposes. Due to the expensive nature of the antibody drugs, identification of broad-spectrum antivirals is essential along with focusing on small interfering RNAs (siRNAs). High pathogenicity of NiV in humans, and lack of vaccines or therapeutics to counter this disease have attracted attention of researchers worldwide for developing effective NiV vaccine and treatment regimens.

Nipah virus: A review on epidemiological characteristics and outbreaks to inform public health decision making

The objectives of this review were to understand the epidemiology and outbreak of NiV infection and to discuss the preventive and control measures across different regions. We searched PubMed and Scopus for relevant articles from January 1999 to July 2018 and identified 927 articles which were screened for titles, abstracts and full texts by two review authors independently. The screening process resulted in 44 articles which were used to extract relevant information. Information on epidemiology of NiV, outbreaks in Malaysia, Singapore, Bangladesh, India and Philippines, including diagnosis, prevention, treatment, vaccines, control, surveillance and economic burden due to NiV were discussed. Interdisciplinary and multi sectoral approach is vital in preventing the emergence of NiV. It is necessary to undertake rigorous research for developing vaccines and medicines to prevent and treat NiV.

Isolation and characterization of novel bat paramyxovirus B16-40 potentially belonging to the proposed genus Shaanvirus

The bat paramyxovirus B16-40 was first isolated in Korea in this study. Using the isolated virus, we could obtain not only genomic information, but also several biological characteristics of the virus. In the phylogenetic analysis, the virus was found to belong to the recently proposed genus Shaanvirus. Through sequence analyses and in vitro testing, the isolated virus was also found to have haemagglutinin-neuraminidase (HN) protein as one of the structural proteins. When mouse antiserum was generated against the isolated virus and tested, it was cross-reactive to human parainfluenza virus 1 in an indirect immunofluorescence assay but could not cross-neutralize human parainfluenza virus 1. In addition, the bat paramyxovirus B16-40 was not infectious in the mouse model. Collectively, this study provided basic information on further classification of the bat paramyxovirus B16-40 and related viruses in the proposed genus Shaanvirus.

High diversity of picornaviruses in rats from different continents revealed by deep sequencing

Outbreaks of zoonotic diseases in humans and livestock are not uncommon, and an important component in containment of such emerging viral diseases is rapid and reliable diagnostics. Such methods are often PCR-based and hence require the availability of sequence data from the pathogen. Rattus norvegicus (R. norvegicus) is a known reservoir for important zoonotic pathogens. Transmission may be direct via contact with the animal, for example, through exposure to its faecal matter, or indirectly mediated by arthropod vectors. Here we investigated the viral content in rat faecal matter (n=29) collected from two continents by analyzing 2.2 billion next-generation sequencing reads derived from both DNA and RNA. Among other virus families, we found sequences from members of the Picornaviridae to be abundant in the microbiome of all the samples. Here we describe the diversity of the picornavirus-like contigs including near-full-length genomes closely related to the Boone cardiovirus and Theiler's encephalomyelitis virus. From this study, we conclude that picornaviruses within R. norvegicus are more diverse than previously recognized. The virome of R. norvegicus should be investigated further to assess the full potential for zoonotic virus transmission.

Nipah virus matrix protein: expert hacker of cellular machines

Nipah virus (NiV, Henipavirus) is a highly lethal emergent zoonotic paramyxovirus responsible for repeated human outbreaks of encephalitis in South East Asia. There are no approved vaccines or treatments, thus improved understanding of NiV biology is imperative. NiV matrix protein recruits a plethora of cellular machinery to scaffold and coordinate virion budding. Intriguingly, matrix also hijacks cellular trafficking and ubiquitination pathways to facilitate transient nuclear localization. While the biological significance of matrix nuclear localization for an otherwise cytoplasmic virus remains enigmatic, the molecular details have begun to be characterized, and are conserved among matrix proteins from divergent paramyxoviruses. Matrix protein appropriation of cellular machinery will be discussed in terms of its early nuclear targeting and later role in virion assembly.

Two highly similar LAEDDTNAQKT and LTDKIGTEI epitopes in G glycoprotein may be useful for effective epitope based vaccine design against pathogenic Henipavirus

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Computational approaches were used to identify epitopes for vaccine development against Henipavirus.

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The strategy combines B-cell epitope prediction, T-cell epitope prediction, docking simulation assay, and cytotoxicity analysis of the G glycoprotein.

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Two potential epitopes were predicted which may be used for the development of peptide vaccines.

Nipah virus and Hendra virus, two members of the genus Henipavirus, are newly emerging zoonotic pathogens which cause acute respiratory illness and severe encephalitis in human. Lack of the effective antiviral therapy endorses the urgency for the development of vaccine against these deadly viruses. In this study, we employed various computational approaches to identify epitopes which has the potential for vaccine development. By analyzing the immune parameters of the conserved sequences of G glycoprotein using various databases and bioinformatics tools, we identified two potential epitopes which may be used as peptide vaccines. Using different B cell epitope prediction servers, four highly similar B cell epitopes were identified. Immunoinformatics analyses revealed that LAEDDTNAQKT is a highly flexible and accessible B-cell epitope to antibody. Highly similar putative CTL epitopes were analyzed for their binding with the HLA-C 12*03 molecule. Docking simulation assay revealed that LTDKIGTEI has significantly lower binding energy, which bolstered its potential as epitope-based vaccine design. Finally, cytotoxicity analysis has also justified their potential as promising epitope-based vaccine candidate. In sum, our computational analysis indicates that either LAEDDTNAQKT or LTDKIGTEI epitope holds a promise for the development of universal vaccine against all kinds of pathogenic Henipavirus. Further in vivo and in vitro studies are necessary to validate the obtained findings.

Outbreak of henipavirus infection, Philippines, 2014

During 2014, henipavirus infection caused severe illness among humans and horses in southern Philippines; fatality rates among humans were high. Horse-to-human and human-to-human transmission occurred. The most likely source of horse infection was fruit bats. Ongoing surveillance is needed for rapid diagnosis, risk factor investigation, control measure implementation, and further virus characterization.

Structural characterization by transmission electron microscopy and immunoreactivity of recombinant Hendra virus nucleocapsid protein expressed and purified from Escherichia coli

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Recombinant HeV N was expressed in a soluble from in E. coli.

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HeV N purified by IMAC and SEC formed higher order oligomers.

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Negative-stain EM images of recombinant HeV N indicated self-assembly to form helical chains of nucleocapsids.

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Recombinant forms of HeV N were immuno-reactive with sera from infected animals and humans.

Hendra virus (family Paramyxoviridae) is a negative sense single-stranded RNA virus (NSRV) which has been found to cause disease in humans, horses, and experimentally in other animals, e.g. pigs and cats. Pteropid bats commonly known as flying foxes have been identified as the natural host reservoir. The Hendra virus nucleocapsid protein (HeV N) represents the most abundant viral protein produced by the host cell, and is highly immunogenic with naturally infected humans and horses producing specific antibodies towards this protein.

The purpose of this study was to express and purify soluble, functionally active recombinant HeV N, suitable for use as an immunodiagnostic reagent to detect antibodies against HeV. We expressed both full-length HeV N, (HeV N_FL), and a C-terminal truncated form, (HeV N_CORE), using a bacterial heterologous expression system. Both HeV N constructs were engineered with an N-terminal His_x6 tag, and purified using a combination of immobilized metal affinity chromatography (IMAC) and size exclusion chromatography (SEC). Purified recombinant HeV N proteins self-assembled into soluble higher order oligomers as determined by SEC and negative-stain transmission electron microscopy. Both HeV N proteins were highly immuno-reactive with sera from animals and humans infected with either HeV or the closely related Nipah virus (NiV), but displayed no immuno-reactivity towards sera from animals infected with a non-pathogenic paramyxovirus (CedPV), or animals receiving Equivac® (HeV G glycoprotein subunit vaccine), using a Luminex-based multiplexed microsphere assay.

Inhibitors of cellular kinases with broad-spectrum antiviral activity for hemorrhagic fever viruses

Host cell kinases are important for the replication of a number of hemorrhagic fever viruses. We tested a panel of kinase inhibitors for their ability to block the replication of multiple hemorrhagic fever viruses. OSU-03012 inhibited the replication of Lassa, Ebola, Marburg and Nipah viruses, whereas BIBX 1382 dihydrochloride inhibited Lassa, Ebola and Marburg viruses. BIBX 1382 blocked both Lassa and Ebola virus glycoprotein-dependent cell entry. These compounds may be used as tools to understand conserved virus-host interactions, and implicate host cell kinases that may be targets for broad spectrum therapeutic intervention.

Henipaviruses are not yet history

ABSTRACT 

Within the Paramyxoviridae family, Henipaviruses are the deadliest human pathogens. Nipah and Hendra viruses comprise the genus Henipavirus, zoonotic pathogens which cause encephalitis and respiratory disease in humans with mortality rates that can exceed 70%. Henipaviruses are the only Paramyxoviruses classified as biosafety level 4 pathogens due to their extreme pathogenicity, potential for bioterrorism and lack of available licensed vaccines or therapeutic modalities. Both viruses emerged from their natural reservoir, Asian fruit bats, during the last decade of the 20th century. They caused severe disease and mortality in humans, horses and swine. They also infected a number of other mammalian species. With significant progress in understanding the biology of these deadly pathogens, including the discovery of a Hendra virus vaccine and a potential neutralizing antibody, have we really won the war against the Henipavirus?

Viral sensing at the blood-brain barrier: new roles for innate immunity at the CNS vasculature

Neurotropic viral infections are a major source of disease worldwide and represent a growing burden to public health. While the central nervous system (CNS) is normally protected from viral infection by the blood-brain barrier (BBB), many viruses are able to cross the BBB and establish CNS infection through processes that largely remain poorly understood. A growing body of recent research has begun to shed light on the viral and host factors that modulate BBB function, contributing to both protective and pathological disease processes. Central to these studies have been the actions of host cytokines and chemokines, which have increasingly been shown to be key regulators of BBB physiology. This review summarizes recent advances in understanding how BBB function governs both viral pathogenesis and host immune responses during neurotropic viral infections.

What is new about epidemiology of acute infectious encephalitis?

PURPOSE OF REVIEW

This review aims to describe new features on the epidemiology of encephalitis world-wide. As this neurological presentation is most frequently related to transmitted viruses, surveillance of encephalitis is of major importance to detect their emergence or re-emergence.

RECENT FINDINGS

Rabies causes one of the most severe types of encephalitis as it is lethal in all cases, and it is endemic in some countries. It was thought that the virus had been eradicated in Western Europe, but it re-emerged in Greece and Italy. Physicians should be aware of this diagnosis in the case of severe encephalitis. Some viruses (Powassan, Nipah, and Hendra) are becoming endemic in some new parts of the world (USA and Australia). Because of their severity, they are healthcare concerns in those countries and for travelers (e.g. in Asia). Finally, a concept is emerging: herpes simplex virus is suspected to be a trigger for autoimmune encephalitis. This is of major importance for the future management of patients (corticosteroids early in the course of the disease?), and the epidemiology of sequelae.

SUMMARY

Encephalitis is a good marker for the detection of emerging infections. New findings about the relationship between herpes simplex virus encephalitis and autoimmune encephalitis open a new concept for a better management of patients.

Rhabdovirus-based vaccine platforms against henipaviruses

The emerging zoonotic pathogens Hendra virus (HeV) and Nipah virus (NiV) are in the genus Henipavirus in the family Paramyxoviridae. HeV and NiV infections can be highly fatal to humans and livestock. The goal of this study was to develop candidate vaccines against henipaviruses utilizing two well-established rhabdoviral vaccine vector platforms, recombinant rabies virus (RABV) and recombinant vesicular stomatitis virus (VSV), expressing either the codon-optimized or the wild-type (wt) HeV glycoprotein (G) gene. The RABV vector expressing the codon-optimized HeV G showed a 2- to 3-fold increase in incorporation compared to the RABV vector expressing wt HeV G. There was no significant difference in HeV G incorporation in the VSV vectors expressing either wt or codon-optimized HeV G. Mice inoculated intranasally with any of these live recombinant viruses showed no signs of disease, including weight loss, indicating that HeV G expression and incorporation did not increase the neurotropism of the vaccine vectors. To test the immunogenicity of the vaccine candidates, we immunized mice intramuscularly with either one dose of the live vaccines or 3 doses of 10 μg chemically inactivated viral particles. Increased codon-optimized HeV G incorporation into RABV virions resulted in higher antibody titers against HeV G compared to inactivated RABV virions expressing wt HeV G. The live VSV vectors induced more HeV G-specific antibodies as well as higher levels of HeV neutralizing antibodies than the RABV vectors. In the case of killed particles, HeV neutralizing serum titers were very similar between the two platforms. These results indicated that killed RABV with codon-optimized HeV G should be the vector of choice as a dual vaccine in areas where rabies is endemic.

IMPORTANCE

Scientists have been tracking two new viruses carried by the Pteropid fruit bats: Hendra virus (HeV) and Nipah virus (NiV). Both viruses can be fatal to humans and also pose a serious risk to domestic animals. A recent escalation in the frequency of outbreaks has increased the need for a vaccine that prevents HeV and NiV infections. In this study, we performed an extensive comparison of live and killed particles of two recombinant rhabdoviral vectors, rabies virus and vesicular stomatitis virus (VSV), expressing wild-type or codon-optimized HeV glycoprotein, with the goal of developing a candidate vaccine against HeV. Based on our data from the presented mouse immunogenicity studies, we conclude that a killed RABV vaccine would be highly effective against HeV infections and would make an excellent vaccine candidate in areas where both RABV and henipaviruses pose a threat to human health.

Matrix proteins of Nipah and Hendra viruses interact with beta subunits of AP-3 complexes

Paramyxoviruses and other negative-strand RNA viruses encode matrix proteins that coordinate the virus assembly process. The matrix proteins link the viral glycoproteins and the viral ribonucleoproteins at virus assembly sites and often recruit host machinery that facilitates the budding process. Using a co-affinity purification strategy, we have identified the beta subunit of the AP-3 adapter protein complex, AP3B1, as a binding partner for the M proteins of the zoonotic paramyxoviruses Nipah virus and Hendra virus. Binding function was localized to the serine-rich and acidic Hinge domain of AP3B1, and a 29-amino-acid Hinge-derived polypeptide was sufficient for M protein binding in coimmunoprecipitation assays. Virus-like particle (VLP) production assays were used to assess the relationship between AP3B1 binding and M protein function. We found that for both Nipah virus and Hendra virus, M protein expression in the absence of any other viral proteins led to the efficient production of VLPs in transfected cells, and this VLP production was potently inhibited upon overexpression of short M-binding polypeptides derived from the Hinge region of AP3B1. Both human and bat (Pteropus alecto) AP3B1-derived polypeptides were highly effective at inhibiting the production of VLPs. VLP production was also impaired through small interfering RNA (siRNA)-mediated depletion of AP3B1 from cells. These findings suggest that AP-3-directed trafficking processes are important for henipavirus particle production and identify a new host protein-virus protein binding interface that could become a useful target in future efforts to develop small molecule inhibitors to combat paramyxoviral infections.

IMPORTANCE

Henipaviruses cause deadly infections in humans, with a mortality rate of about 40%. Hendra virus outbreaks in Australia, all involving horses and some involving transmission to humans, have been a continuing problem. Nipah virus caused a large outbreak in Malaysia in 1998, killing 109 people, and smaller outbreaks have since occurred in Bangladesh and India. In this study, we have defined, for the first time, host factors that interact with henipavirus M proteins and contribute to viral particle assembly. We have also defined a new host protein-viral protein binding interface that can potentially be targeted for the inhibition of paramyxovirus infections.

Mitochondrial genome of the black flying fox, Pteropus alecto (Chiroptera: Megachiroptera: Pteropodidae)

In this article we report the complete mitochondrial genome of black flying fox, Pteropus alecto, with the sequence length of 16,739 bp for the first time. The mitogenome contained a total of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region. The base composition was A (33.1%), G (14.5%), C (27.2%) and T (25.2%), indicating that the percentage of A and T (58.3%) was higher than that of G and C. Most of these genes were distributed on the H-strand, except for the ND6 subunit gene and eight tRNA genes. The mitochondrial genome analyzed here will provide new genetic information to study the evolution of bats.

Surface glycoproteins of the recently identified African Henipavirus promote viral entry and cell fusion in a range of human, simian and bat cell lines

The recent discovery of a wide range of henipavirus-like viruses circulating in Megabats in Africa raises the question as to the zoonotic potential of these pathogens given the high human mortality rates seen with their pathogenic relatives Nipah virus and Hendra virus. In the absence of cultured infectious African Henipavirus we have performed experiments with recombinant F and G glycoproteins from the representative African Henipavirus strain M74a aimed at estimating its cellular tropism and capacity to use similar receptors to its highly pathogenic counterparts. The ability of the M74a virus G surface protein to use the ubiquitous Ephrin B2 host cell receptor and its heterologous cross-compatibility with Nipah virus could be expected to impart upon this virus a reasonable potential for species spillover, although differences in fusion efficiency seen with the M74a virus F protein in certain cell lines could present a barrier for zoonotic transmission.