Newcastle disease virus V protein is a determinant of host range restriction

Human parainfluenza virus type 2 V protein inhibits mitochondrial apoptosis pathway through two ways

Paramyxoviruses are reported to block apoptosis for their replication, but the mechanisms remain unclear. Furthermore, regulation of mitochondrial apoptosis by paramyxoviruses has been hardly reported. We investigated whether and how human parainfluenza virus type 2 (hPIV-2) counteracts apoptosis. Infection of recombinant hPIV-2 carrying mutated V protein showed higher caspase 3/7 activity and higher cytochrome c release from mitochondria than wild type hPIV-2 infection. This indicates that V protein controls mitochondrial apoptosis pathway. hPIV-2 V protein interacted with Bad, an apoptotic promoting protein, and this interaction inhibited the binding of Bad to Bcl-XL. V protein also bound to 14-3-3ε, which was essential for inhibition of 14-3-3ε cleavage. Our data collectively suggest that hPIV-2 V protein has two means of preventing mitochondrial apoptosis pathway: the inhibition of Bad-Bcl-XL interaction and the suppression of 14-3-3ε cleavage. This is the first report of the mechanisms behind how paramyxoviruses modulate mitochondrial apoptosis pathways.

The W195 Residue of the Newcastle Disease Virus V Protein Is Critical for Multiple Aspects of Viral Self-Regulation through Interactions between V and Nucleoproteins

The transcription and replication of the Newcastle disease virus (NDV) strictly rely on the viral ribonucleoprotein (RNP) complex, which is composed of viral NP, P, L and RNA. However, it is not known whether other viral non-RNP proteins participate in this process for viral self-regulation. In this study, we used a minigenome (MG) system to identify the regulatory role of the viral non-RNP proteins V, M, W, F and HN. Among them, V significantly reduced MG-encoded reporter activity compared with the other proteins and inhibited the synthesis of viral mRNA and cRNA. Further, V interacted with NP. A mutation in residue W195 of V diminished V-NP interaction and inhibited inclusion body (IB) formation in NP-P-L-cotransfected cells. Furthermore, a reverse-genetics system for the highly virulent strain F48E9 was established. The mutant rF48E9-VW195R increased viral replication and apparently enhanced IB formation. In vivo experiments demonstrated that rF48E9-VW195R decreased virulence and retarded time of death. Overall, the results indicate that the V-NP interaction of the W195 mutant V decreased, which regulated viral RNA synthesis, IB formation, viral replication and pathogenicity. This study provides insight into the self-regulation of non-RNP proteins in paramyxoviruses.

Direct interaction of the molecular chaperone GRP78/BiP with the Newcastle disease virus hemagglutinin-neuraminidase protein plays a vital role in viral attachment to and infection of culture cells

Introduction

Glucose Regulated Proteins/Binding protein (GRP78/Bip), a representative molecular chaperone, effectively influences and actively participates in the replication processes of many viruses. Little is known, however, about the functional involvement of GRP78 in the replication of Newcastle disease virus (NDV) and the underlying mechanisms.

Methods

The method of this study are to establish protein interactomes between host cell proteins and the NDV Hemagglutinin-neuraminidase (HN) protein, and to systematically investigate the regulatory role of the GRP78-HN protein interaction during the NDV replication cycle.

Results

Our study revealed that GRP78 is upregulated during NDV infection, and its direct interaction with HN is mediated by the N-terminal 326 amino acid region. Knockdown of GRP78 by small interfering RNAs (siRNAs) significantly suppressed NDV infection and replication. Conversely, overexpression of GRP78 resulted in a significant increase in NDV replication, demonstrating its role as a positive regulator in the NDV replication cycle. We further showed that the direct interaction between GRP78 and HN protein enhanced the attachment of NDV to cells, and masking of GRP78 expressed on the cell surface with specific polyclonal antibodies (pAbs) inhibited NDV attachment and replication.

Discussion

These findings highlight the essential role of GRP78 in the adsorption stage during the NDV infection cycle, and, importantly, identify the critical domain required for GRP78-HN interaction, providing novel insights into the molecular mechanisms involved in NDV replication and infection.

Multifunctionality of matrix protein in the replication and pathogenesis of Newcastle disease virus: A review

As an important structural protein in virion morphogenesis, the matrix (M) protein of Newcastle disease virus (NDV) is demonstrated to be a nuclear-cytoplasmic trafficking protein and plays essential roles in viral assembly and budding. In recent years, increasing lines of evidence have indicated that the M protein has obvious influence on the pathotypes of NDV, and the interaction of M protein with cellular proteins is also closely associated with the replication and pathogenicity of NDV. Although substantial progress has been made in the past 40 years towards understanding the structure and function of NDV M protein, the available information is scattered. Therefore, this review article summarizes and updates the research progress on the structural feature, virulence and pathotype correlation, and nucleocytoplasmic transport mechanism of NDV M protein, as well as the functions of M protein and cellular protein interactions in M's intracellular localization, viral RNA synthesis and transcription, viral protein synthesis, viral immune evasion, and viral budding and release, which will provide an in-depth understanding of the biological functions of M protein in the replication and pathogenesis of NDV, and also contribute to the development of effective antiviral strategies aiming at blocking the early or late steps of NDV lifecycles.

The Viral Knock: Ameliorating Cancer Treatment with Oncolytic Newcastle Disease Virus

The prospect of cancer treatment has drastically transformed over the last four decades. The side effects caused by the traditional methods of cancer treatment like surgery, chemotherapy, and radiotherapy through the years highlight the prospect for a novel, complementary, and alternative cancer therapy. Oncolytic virotherapy is an evolving treatment modality that utilizes oncolytic viruses (OVs) to selectively attack cancer cells by direct lysis and can also elicit a strong anti-cancer immune response. Newcastle disease virus (NDV) provides a very high safety profile compared to other oncolytic viruses. Extensive research worldwide concentrates on experimenting with and better understanding the underlying mechanisms by which oncolytic NDV can be effectively applied to intercept cancer. This review encapsulates the potential of NDV to be explored as an oncolytic agent and discusses current preclinical and clinical research scenarios involving various NDV strains.

The synergistic effect of residues 32T and 550L in the PA protein of H5 subtype avian influenza virus contributes to viral pathogenicity in mice

The avian influenza virus (AIV) PA protein contributes to viral replication and pathogenicity; however, its interaction with innate immunity is not well understood. Here, we report that the H5 subtype AIV PA protein strongly suppresses host antiviral defense by interacting with and degrading a key protein in interferon (IFN) signaling, Janus kinase 1 (JAK1). Specifically, the AIV PA protein catalyzes the K48-linked polyubiquitination and degradation of JAK1 at lysine residue 249. Importantly, the AIV PA protein harboring 32T/550L degrades both avian and mammalian JAK1, while the AIV PA protein with residues 32M/550I degrades avian JAK1 only. Furthermore, the residues 32T/550L in PA protein confer optimum polymerase activity and AIV growth in mammalian cells. Notably, the replication and virulence of the AIV PA T32M/L550I mutant are attenuated in infected mice. Collectively, these data reveal an interference role for H5 subtype AIV PA protein in host innate immunity, which can be targeted for the development of specific and effective anti-influenza therapeutics.

Molecular characterization suggests kinetic modulation of expression of accessory viral protein, W, in Newcastle disease virus infected DF1 cells

Viruses adopt strategies to efficiently utilize their compact genome. Members of the family Paramyxoviridae, exhibit a cotranscriptional RNA editing mechanism wherein polymerase stuttering generates accessory proteins from Phosphoprotein (P) gene. Newcastle disease virus (NDV), an avian paramyxovirus, expresses two accessory proteins, V and W, by RNA editing. While P and V proteins are well studied, very little is known about W protein. Recent studies confirmed W protein expression in NDV and the unique subcellular localization of W proteins of virulent and avirulent NDV. We characterized the W protein of NDV strain Komarov, a moderately virulent vaccine strain. W mRNA expression ranged between 7 and 9% of total P gene transcripts similar to virulent NDV. However, W protein expression, detectable by 6 h, peaked at 24 h and dropped by 48 h post infection in DF1 cells indicating a kinetically regulated expression by the virus. The W protein localized in the nucleus and by mutations, a strong nuclear localization signal was identified in the C-terminal region of W protein. The viral growth kinetics study suggested neither supplementation of W protein nor subcellular localization pattern of the supplemented W protein influenced viral replication in vitro similar to that noticed in avirulent NDV. A cytoplasmic mutant of W protein localized in cytoplasm unlike specific mitochondrial colocalization as recorded in velogenic NDV strain SG10 indicating a possible role of W protein in determining the viral pathogenicity. This study describes for the first time, the distinct features of W protein of moderately virulent NDV.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-023-00813-2.

Interim safety and immunogenicity results from an NDV-based COVID-19 vaccine phase I trial in Mexico

There is still a need for safe, efficient, and low-cost coronavirus disease 2019 (COVID-19) vaccines that can stop transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here we evaluated a vaccine candidate based on a live recombinant Newcastle disease virus (NDV) that expresses a stable version of the spike protein in infected cells as well as on the surface of the viral particle (AVX/COVID-12-HEXAPRO, also known as NDV-HXP-S). This vaccine candidate can be grown in embryonated eggs at a low cost, similar to influenza virus vaccines, and it can also be administered intranasally, potentially to induce mucosal immunity. We evaluated this vaccine candidate in prime-boost regimens via intramuscular, intranasal, or intranasal followed by intramuscular routes in an open-label non-randomized non-placebo-controlled phase I clinical trial in Mexico in 91 volunteers. The primary objective of the trial was to assess vaccine safety, and the secondary objective was to determine the immunogenicity of the different vaccine regimens. In the interim analysis reported here, the vaccine was found to be safe, and the higher doses tested were found to be immunogenic when given intramuscularly or intranasally followed by intramuscular administration, providing the basis for further clinical development of the vaccine candidate. The study is registered under ClinicalTrials.gov identifier NCT04871737.

Viral vectored vaccines: design, development, preventive and therapeutic applications in human diseases

Human diseases, particularly infectious diseases and cancers, pose unprecedented challenges to public health security and the global economy. The development and distribution of novel prophylactic and therapeutic vaccines are the prioritized countermeasures of human disease. Among all vaccine platforms, viral vector vaccines offer distinguished advantages and represent prominent choices for pathogens that have hampered control efforts based on conventional vaccine approaches. Currently, viral vector vaccines remain one of the best strategies for induction of robust humoral and cellular immunity against human diseases. Numerous viruses of different families and origins, including vesicular stomatitis virus, rabies virus, parainfluenza virus, measles virus, Newcastle disease virus, influenza virus, adenovirus and poxvirus, are deemed to be prominent viral vectors that differ in structural characteristics, design strategy, antigen presentation capability, immunogenicity and protective efficacy. This review summarized the overall profile of the design strategies, progress in advance and steps taken to address barriers to the deployment of these viral vector vaccines, simultaneously highlighting their potential for mucosal delivery, therapeutic application in cancer as well as other key aspects concerning the rational application of these viral vector vaccines. Appropriate and accurate technological advances in viral vector vaccines would consolidate their position as a leading approach to accelerate breakthroughs in novel vaccines and facilitate a rapid response to public health emergencies.

Expanding cross-presenting dendritic cells enhances oncolytic virotherapy and is critical for long-term anti-tumor immunity

Immunotherapies directly enhancing anti-tumor CD8⁺ T cell responses have yielded measurable but limited success, highlighting the need for alternatives. Anti-tumor T cell responses critically depend on antigen presenting dendritic cells (DC), and enhancing mobilization, antigen loading and activation of these cells represent an attractive possibility to potentiate T cell based therapies. Here we show that expansion of DCs by Flt3L administration impacts in situ vaccination with oncolytic Newcastle Disease Virus (NDV). Mechanistically, NDV activates DCs and sensitizes them to dying tumor cells through upregulation of dead-cell receptors and synergizes with Flt3L to promote anti-tumor CD8⁺ T cell cross-priming. In vivo, Flt3L-NDV in situ vaccination induces parallel amplification of virus- and tumor-specific T cells, including CD8⁺ T cells reactive to newly-described neoepitopes, promoting long-term tumor control. Cross-presenting conventional Type 1 DCs are indispensable for the anti-tumor, but not anti-viral, T cell response, and type I IFN-dependent CD4⁺ Th1 effector cells contribute to optimal anti-tumor immunity. These data demonstrate that mobilizing DCs to increase tumor antigen cross-presentation improves oncolytic virotherapy and that neoepitope-specific T cells can be induced without individualized, ex vivo manufactured vaccines.

The influenza virus PB2 protein evades antiviral innate immunity by inhibiting JAK1/STAT signalling

Influenza A virus (IAV) polymerase protein PB2 has been shown to partially inhibit the host immune response by blocking the induction of interferons (IFNs). However, the IAV PB2 protein that regulates the downstream signaling pathway of IFNs is not well characterized. Here, we report that IAV PB2 protein reduces cellular sensitivity to IFNs, suppressing the activation of STAT1/STAT2 and ISGs. Furthermore, IAV PB2 protein targets mammalian JAK1 at lysine 859 and 860 for ubiquitination and degradation. Notably, the H5 subtype of highly pathogenic avian influenza virus with I283M/K526R mutations on PB2 increases the ability to degrade mammalian JAK1 and exhibits higher replicate efficiency in mammalian (but not avian) cells and mouse lung tissues, and causes greater mortality in infected mice. Altogether, these data describe a negative regulatory mechanism involving PB2-JAK1 and provide insights into an evasion strategy from host antiviral immunity employed by IAV.

Mucosal delivery of RNA vaccines by Newcastle disease virus vectors

The rapid evolution of SARS-CoV-2 since its pandemic outbreak has underscored the need for improved SARS-CoV-2 vaccines that efficiently reduce not only hospitalizations and deaths, but also infections and transmission. This might be achieved by a new generation of intranasally administered SARS-CoV-2 vaccines to stimulate protective mucosal immunity. Among all different approaches, preclinical and clinical information using Newcastle Disease Virus (NDV)-vectors expressing S of SARS-CoV2 as a COVID-19 vaccine show the potential of this vaccine platform as an affordable, highly immunogenic, safe strategy to intranasally vaccinate humans against SARS-CoV-2 and other infectious diseases. These vaccine vectors consist on the use of a harmless avian negative strand RNA virus to deliver intranasally a self-replicating RNA expressing the vaccine antigen in the cells of the respiratory mucosa. The vector also incorporates the antigen in the virus particle used for RNA delivery, thus combining the properties of nanoparticle-based and RNA-based vaccines. Other advantages of NDV-based vectors include the worldwide availability of manufacturing facilities for their production and their stability at non-freezing temperatures. While phase 3 clinical studies to evaluate efficacy are still pending, phase 1 and 2 clinical studies have demonstrated the safety and immunogenicity of NDV-S vaccines against SARS-CoV-2.

Review detection of Newcastle disease virus

Newcastle disease (ND) is an acute and highly contagious disease caused by the Newcastle disease virus (NDV) infecting poultry, which has caused great harm to the poultry industry around the world. Rapid diagnosis of NDV is important to early treatment and early institution of control measures. In this review, we comprehensively summarize the most recent research into NDV, including historical overview, molecular structure, and infection mechanism. We then focus on detection strategies for NDV, including virus isolation, serological assays (such as hemagglutination and hemagglutination-inhibition tests, enzyme linked immunosorbent assay, reporter virus neutralization test, Immunofluorescence assay, and Immune colloidal gold technique), molecular assays (such as reverse transcription polymerase chain reaction, real-time quantitative PCR, and loop-mediated isothermal amplification) and other assays. The performance of the different serological and molecular biology assays currently available was also analyzed. To conclude, we examine the limitations of currently available strategies for the detection of NDV to lay the groundwork for new detection assays.

Avian Paramyxovirus 4 Antitumor Activity Leads to Complete Remissions and Long-term Protective Memory in Preclinical Melanoma and Colon Carcinoma Models

Avulaviruses represent a diverse subfamily of non-segmented negative strand RNA viruses infecting avian species worldwide. To date, 22 different serotypes have been identified in a variety of avian hosts, including wild and domestic birds. APMV-1, also known as Newcastle disease virus (NDV), is the only avulavirus that has been extensively characterized due to its relevance for the poultry industry and, more recently, its inherent oncolytic activity and potential as a cancer therapeutic. An array of both naturally-occurring and recombinant APMV-1 strains has been tested in different preclinical models and clinical trials, highlighting NDV as a promising viral agent for human cancer therapy. To date, the oncolytic potential of other closely related avulaviruses remains unknown. Here, we have examined the in vivo anti-tumor capability of prototype strains of APMV serotypes -2, -3, -4, -6, -7, -8 and -9 in syngeneic murine colon carcinoma and melanoma tumor models. Our studies have identified APMV-4 Duck/Hong Kong/D3/1975 virus as a novel oncolytic agent with greater therapeutic potential than one of the NDV clinical candidate strains, La Sota. Intratumoral administration of the naturally-occurring APMV-4 virus significantly extends survival, promotes complete remission, and confers protection against re-challenge in both murine colon carcinoma and melanoma tumor models. Furthermore, we have designed a plasmid rescue strategy that allows us to develop recombinant APMV-4-based viruses. The infectious clone rAPMV-4 preserves the extraordinary antitumor capacity of its natural counterpart, paving the way to a promising next generation of viral therapeutics.

Encoding of a transgene in-frame with a Newcastle disease virus protein increases transgene expression and stability

Newcastle disease virus (NDV) has been extensively explored as a vector for vaccine and oncolytic therapeutic development. In conventional NDV-based vectors, the transgene is arranged as a separate transcription unit in the NDV genome. Here, we expressed haemagglutinin protein (HA) of an avian influenza virus using an NDV vector design in which the transgene ORF is encoded in-frame with the ORF of an NDV gene. This arrangement does not increase the number of transcription units in the NDV genome, and imposes a selection pressure against mutations interrupting the transgene ORF. We placed the HA ORF upstream or downstream of N, M, F and HN ORFs of NDV so that both proteins are encoded in-frame and are separated by either a self-cleaving 2A peptide, furin cleavage site or both. Only constructs in which HA was placed downstream of the NDV HN were viable. These constructs expressed the transgene at a higher level compared to the vector encoding the same transgene in the same position in the NDV genome but as a separate transcription unit. Furthermore, the transgene expressed in one ORF with the NDV protein proved to be more stable over multiple passages. Thus, this design may be useful for applications where the stability of the transgene expression is highly important for a recombinant NDV vector.

In Silico Analysis of Plant Flavonoids as Potential Inhibitors of Newcastle Disease Virus V Protein

Newcastle disease is a viral infection causing serious economic losses to the global poultry industry. The V protein of Newcastle disease virus (NDV) is a pathogenicity determinant having various functions such as the suppression of apoptosis and replication of the NDV. This study was designed to assess the resistance potential of plant flavonoids against the V protein of Newcastle disease virus. Sequence analysis was performed using EXPASY and ProtParam tools. To build the three-dimensional structure of V protein, a homology-modeling method was used. Plant flavonoids with formerly reported therapeutic benefits were collected from different databases to build a library for virtual screening. Docking analysis was performed using the modeled structure of V protein on MOE software. Interaction analysis was also performed by MOE to explain the results of docking. Sequence analysis and physicochemical properties showed that V protein is negatively charged, acidic in nature, and relatively unstable. The 3D structure of the V protein showed eight β-pleated sheets, three helices, and ten coiled regions. Based on docking score, ten flavonoids were selected as potential inhibitors of V protein. Furthermore, a common configuration was obtained among these ten flavonoids. The interaction analysis also identified the atoms involved in every interaction of flavonoid and V protein. Molecular dynamics (MD) simulation confirmed the stability of two compounds, quercetin-7-O-[α-L-rhamnopyranosyl(1→6)-β-D-galactopyranoside] and luteolin 7-O-neohesperidoside, at 100 ns with V protein. The identified compounds through molecular docking and MD simulation could have potential as NDV-V protein inhibitor after further validation. This study could be useful for the designing of anti-NDV drugs.

Molecular Mechanisms of Anti-Neoplastic and Immune Stimulatory Properties of Oncolytic Newcastle Disease Virus

Oncolytic viruses represent interesting anti-cancer agents with high tumor selectivity and immune stimulatory potential. The present review provides an update of the molecular mechanisms of the anti-neoplastic and immune stimulatory properties of the avian paramyxovirus, Newcastle Disease Virus (NDV). The anti-neoplastic activities of NDV include (i) the endocytic targeting of the GTPase Rac1 in Ras-transformed human tumorigenic cells; (ii) the switch from cellular protein to viral protein synthesis and the induction of autophagy mediated by viral nucleoprotein NP; (iii) the virus replication mediated by viral RNA polymerase (large protein (L), associated with phosphoprotein (P)); (iv) the facilitation of NDV spread in tumors via the membrane budding of the virus progeny with the help of matrix protein (M) and fusion protein (F); and (v) the oncolysis via apoptosis, necroptosis, pyroptosis, or ferroptosis associated with immunogenic cell death. A special property of this oncolytic virus consists of its potential for breaking therapy resistance in human cancer cells. Eight examples of this important property are presented and explained. In healthy human cells, NDV infection activates the RIG-MAVs immune signaling pathway and establishes an anti-viral state based on a strong and uninhibited interferon α,ß response. The review also describes the molecular determinants and mechanisms of the NDV-mediated immune stimulatory effects, in which the viral hemagglutinin-neuraminidase (HN) protein plays a prominent role. The six viral proteins provide oncolytic NDV with a special profile in the treatment of cancer.

Optimizing environmental safety and cell-killing potential of oncolytic Newcastle Disease virus with modifications of the V, F and HN genes

Newcastle Disease Virus (NDV) is an avian RNA virus, which was shown to be effective and safe for use in oncolytic viral therapy for several tumour malignancies. The presence of a multi basic cleavage site (MBCS) in the fusion protein improved its oncolytic efficacy in vitro and in vivo. However, NDV with a MBCS can be virulent in poultry. We aimed to develop an NDV with a MBCS but with reduced virulence for poultry while remaining effective in killing human tumour cells. To this end, the open reading frame of the V protein, an avian specific type I interferon antagonist, was disrupted by introducing multiple mutations. NDV with a mutated V gene was attenuated in avian cells and chicken and duck eggs. Although this virus still killed tumour cells, the efficacy was reduced compared to the virulent NDV. Introduction of various mutations in the fusion (F) and hemagglutinin-neuraminidase (HN) genes slightly improved this efficacy. Taken together, these data demonstrated that NDV with a MBCS but with abrogation of the V protein ORF and mutations in the F and HN genes can be safe for evaluation in oncolytic viral therapy.

Safety and immunogenicity of a live recombinant Newcastle disease virus-based COVID-19 vaccine (Patria) administered via the intramuscular or intranasal route: Interim results of a non-randomized open label phase I trial in Mexico

There is still a need for safe, efficient and low-cost coronavirus disease 2019 (COVID-19) vaccines that can stop transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here we evaluated a vaccine candidate based on a live recombinant Newcastle disease virus (NDV) that expresses a stable version of the spike protein in infected cells as well as on the surface of the viral particle (AVX/COVID-12-HEXAPRO, also known as NDV-HXP-S). This vaccine candidate can be grown in embryonated eggs at low cost similar to influenza virus vaccines and it can also be administered intranasally, potentially to induce mucosal immunity. We evaluated this vaccine candidate in prime-boost regimens via intramuscular, intranasal, or intranasal followed by intramuscular routes in an open label non-randomized non-placebo-controlled phase I clinical trial in Mexico in 91 volunteers. The primary objective of the trial was to assess vaccine safety and the secondary objective was to determine the immunogenicity of the different vaccine regimens. In the interim analysis reported here, the vaccine was found to be safe and the higher doses tested were found to be immunogenic when given intramuscularly or intranasally followed by intramuscular administration, providing the basis for further clinical development of the vaccine candidate. The study is registered under ClinicalTrials.gov identifier NCT04871737. Funding was provided by Avimex and CONACYT.

Chicken ISG12(2) attenuates Newcastle disease virus and enhances the efficiency of Newcastle disease vaccine via activating immune pathways

Low virulence and strong immunogenicity are quite important for Newcastle disease virus (NDV) producing Newcastle disease (ND) living-attenuated vaccine. However, immunogenicity of NDV positively correlates to its virulence. Usually, the velogenic NDV induces stronger immune responses of poultry than the lentogenic strain, but virulent NDV poses a risk for chicken. In this study, we identified the chicken interferon (IFN)-stimulated gene 12-2 (ISG12(2)) not only attenuated NDV, but also increased immunogenicity of ND vaccine strain. Firstly, we found that NDV infection or IFNs stimulation induced expression of chicken ISG12(2) that reinforced expression of IFNs. Overexpression or knockdown proved that chicken ISG12(2) inhibited NDV replication. Then, recombinant NDV LaSota strains (rLaSota/Fmut/ISG12(2) and rLaSota/ISG12(2)), expressing ISG12(2), were rescued. Pathogenicity tests showed that ISG12(2) expression attenuated NDV. RNA-seq or RT-qPCR demonstrated that, comparing to rLaSota/Fmut and rLaSota, rLaSota/Fmut/ISG12(2) and rLaSota/ISG12(2) induced hosts to produce cytokines enriching in innate and adaptive immune pathways in vitro and in vivo. Finally, we showed that rLaSota/ISG12(2) vaccination improved immune condition of chicken to quickly response NDV infection and then enhance protection. These results suggest that chicken ISG12(2) is a potential novel molecular adjuvant to regulate immune responses, which decrease virulence and increase immunogenicity of NDV. The chicken ISG12(2) may contribute to development of high efficient poultry vaccine. This article is protected by copyright. All rights reserved.

Safety and Immunogenicity of a Newcastle Disease Virus Vector-Based SARS-CoV-2 Vaccine Candidate, AVX/COVID-12-HEXAPRO (Patria), in Pigs

Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were developed in record time and show excellent efficacy and effectiveness against coronavirus disease 2019 (COVID-19). However, currently approved vaccines cannot meet the global demand. In addition, none of the currently used vaccines is administered intranasally to potentially induce mucosal immunity. Here, we tested the safety and immunogenicity of a second-generation SARS-CoV-2 vaccine that includes a stabilized spike antigen and can be administered intranasally. The vaccine is based on a live Newcastle disease virus vector expressing a SARS-CoV-2 spike protein stabilized in a prefusion conformation with six beneficial proline substitutions (AVX/COVID-12-HEXAPRO; Patria). Immunogenicity testing in the pig model showed that both intranasal and intramuscular application of the vaccine as well as a combination of the two induced strong serum neutralizing antibody responses. Furthermore, substantial reactivity to B.1.1.7, B.1.351, and P.1 spike variants was detected. Finally, no adverse reactions were found in the experimental animals at any dose level or delivery route. These results indicate that the experimental vaccine AVX/COVID-12-HEXAPRO (Patria) is safe and highly immunogenic in the pig model. IMPORTANCE Several highly efficacious vaccines for SARS-CoV-2 have been developed and are used in the population. However, the current production capacity cannot meet the global demand. Therefore, additional vaccines-especially ones that can be produced locally and at low cost-are urgently needed. This work describes preclinical testing of a SARS-CoV-2 vaccine candidate which meets these criteria.

Lentogenic NDV V protein inhibits IFN responses and represses cell apoptosis

The V protein of Newcastle disease virus (NDV) has been shown to inhibit the secretion of interferon (IFN) during infection, which is responsible for the promotion of NDV pathogenicity. However, the ability of the V protein to suppress host innate immunity is not well understood. In this study, we explored the function of V protein and its relationship with virulence by generating V protein-inserted recombinant (r) NDVs. Using rNDVs as a model, we examined the efficiency of infection, IFN responses, and apoptosis of host cells during infection. We found that viral propagation occurred smoothly when V protein from lentogenic NDV is inserted instead of the V protein from the velogenic strain. The infection of lentogenic V protein-inserted rNDV induced less expression of IFNs and downstream antiviral proteins via efficient degradation of p-STAT1 and MDA5. Moreover, velogenic V protein triggered a higher apoptosis rate during infection thereby restricting the replication of NDV. Conversely, lentogenic V protein inhibits IFN responses efficiently and induces less apoptosis compared to the velogenic strain. Our findings provide a novel understanding of the role of V protein in NDV pathogenicity.

Newcastle disease virus V protein interacts with hnRNP H1 to promote viral replication

The interactions between host cellular proteins and viral proteins are important for successful infection by viruses. Previous studies from our group have identified various host cellular proteins that can interact with the Newcastle disease virus V protein (Chu et al., 2018a), but their function in NDV replication has not been fully determined. The present study reports that heterogenous nuclear ribonucleoprotein H1 (hnRNP H1) can interact with NDV V protein in yeast. The immunofluorescence results showed that hnRNP H1 and V protein could colocalize in the cytoplasm of a chicken embryo fibroblast cell line (DF-1 cells). Co-immunoprecipitation assays further verified the interaction of these two proteins. The effects of overexpression and knockdown of hnRNP H1 on NDV replication were evaluated in DF-1 cells through real time quantitative PCR (RT-qPCR) and plaque assays. The regulation of V protein on hnRNP H1 expression was also examined. The results indicated that overexpression of hnRNP H1 facilitated NDV replication, while knockdown of hnRNP H1 decreased NDV replication. It was also shown that V protein could regulate hnRNP H1 expression at the protein level instead of the transcription level. The effect of V protein and hnRNP H1 on the DF-1 cell cycle was also tested and the results revealed that V protein may regulate cell proliferation by controlling the expression of hnRNP H1. Taken together, these results suggest that NDV V protein could promote viral replication by interacting with hnRNP H1.

Musashi1 inhibit the release of Newcastle disease viruses through preventing apoptosis of DF-1 cells

The efficient proliferation of Newcastle disease virus (NDV) depends on its inhibition of host cell innate immunity. V protein acts as a nonstructural protein which plays a significant role in virus replication, whereas its function remains to be further explored. In this study, Musashi RNA binding protein 1 (MSI1) was selected and its interaction with V protein was further verified by Co-immunoprecipitation (Co-IP) and Immuno-colocalization test. Through the transfection of pCMV-HA-MSI1 in DF-1 cells, the overexpression of MSI1 reduced virus particles in the cell supernatant but not reduced mRNA and virus protein in cells pellet, which suggests that MSI1may act as a new antiviral molecule by inhibiting viral release. Cell early apoptosis was detected by flow cytometry (FCM), the result shows that overexpression of MSI1 inhibit cell apoptosis, implying MSI1 Inhibit virus release may through this way. Taken together, MSI1 and NDV V protein has a detectable interaction, and may block apoptosis to inhibit the release of NDV. However, this is the first report about the interaction between MSI1 and V protein of NDV that can inhibit the NDV replicated.

Virulence during Newcastle Disease Viruses Cross Species Adaptation

The hypothesis that host adaptation in virulent Newcastle disease viruses (NDV) has been accompanied by virulence modulation is reviewed here. Historical records, experimental data, and phylogenetic analyses from available GenBank sequences suggest that currently circulating NDVs emerged in the 1920-1940's from low virulence viruses by mutation at the fusion protein cleavage site. These viruses later gave rise to multiple virulent genotypes by modulating virulence in opposite directions. Phylogenetic and pathotyping studies demonstrate that older virulent NDVs further evolved into chicken-adapted genotypes by increasing virulence (velogenic-viscerotropic pathotypes with intracerebral pathogenicity indexes [ICPIs] of 1.6 to 2), or into cormorant-adapted NDVs by moderating virulence (velogenic-neurotropic pathotypes with ICPIs of 1.4 to 1.6), or into pigeon-adapted viruses by further attenuating virulence (mesogenic pathotypes with ICPIs of 0.9 to 1.4). Pathogenesis and transmission experiments on adult chickens demonstrate that chicken-adapted velogenic-viscerotropic viruses are more capable of causing disease than older velogenic-neurotropic viruses. Currently circulating velogenic-viscerotropic viruses are also more capable of replicating and of being transmitted in naïve chickens than viruses from cormorants and pigeons. These evolutionary virulence changes are consistent with theories that predict that virulence may evolve in many directions in order to achieve maximum fitness, as determined by genetic and ecologic constraints.

Chikungunya virus antagonizes cGAS-STING mediated type-I interferon responses by degrading cGAS

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus known to cause epidemics resulting in predominantly symptomatic infections, which in rare cases cause long term debilitating arthritis and arthralgia. Significant progress has been made in understanding the roles of canonical RNA sensing pathways in the host recognition of CHIKV; however, less is known regarding antagonism of CHIKV by cytosolic DNA sensing pathways like that of cyclic GMP-AMP synthase (cGAS) and Stimulator of Interferon Genes (STING). With the use of cGAS or STING null cells we demonstrate that the pathway restricts CHIKV replication in fibroblasts and immune cells. We show that DNA accumulates in the cytoplasm of infected cells and that CHIKV blocks DNA dependent IFN-β transcription. This antagonism of DNA sensing is via an early autophagy-mediated degradation of cGAS and expression of the CHIKV capsid protein is sufficient to induce cGAS degradation. Furthermore, we identify an interaction of CHIKV nsP1 with STING and map the interaction to 23 residues in the cytosolic loop of the adaptor protein. This interaction stabilizes the viral protein and increases the level of palmitoylated nsP1 in cells. Together, this work supports previous publications highlighting the relevance of the cGAS-STING pathway in the early detection of (+)ssRNA viruses and provides direct evidence that CHIKV interacts with and antagonizes cGAS-STING signaling.

Molecular evolution and genetic variations of V and W proteins derived by RNA editing in Avian Paramyxoviruses

The newly assigned subfamily Avulavirinae in the family Paramyxoviridae includes avian paramyxoviruses (APMVs) isolated from a wide variety of avian species across the globe. Till date, 21 species of APMVs are reported and their complete genome sequences are available in GenBank. The APMV genome comprises of a single stranded, negative sense, non-segmented RNA comprising six transcriptional units (except APMV-6 with seven units) each coding for a structural protein. Additionally, by co-transcriptional RNA editing of phosphoprotein (P) gene, two mRNAs coding for accessory viral proteins, V and W, are generated along with unedited P mRNA. However, in APMV-11, the unedited mRNA codes for V protein while +2 edited mRNA translates to P protein, similar to members of subfamily Rubulavirinae in the same family. Such RNA editing in paramyxoviruses enables maximizing the coding capacity of their smaller genome. The three proteins of P gene: P, V and W, share identical N terminal but varied C terminal sequences that contribute to their unique functions. Here, we analyzed the P gene editing site, V and W sequences of all 21 APMV species known so far (55 viruses) by using bioinformatics and report their genetic variations and molecular evolution. The variations observed in the sequence and hexamer phase positions of the P gene editing sites is likely to influence the levels and relative proportions of P, V and W proteins’ expressions which could explain the differences in the pathogenicity of APMVs. The V protein sequences of APMVs had conserved motifs similar to V proteins of other paramyxoviruses including the seven cysteine residues involved in MDA5 interference, STAT1 degradation and interferon antagonism. Conversely, W protein sequences of APMVs were distinct. High sequence homology was observed in both V and W proteins between strains of the same species than between species except in APMV-3 which was the most divergent APMV species. The estimates of synonymous and non-synonymous substitution rates suggested negative selection pressure on the V and W proteins within species indicating their low evolution rate. The molecular clock analysis revealed higher conservation of  V protein sequence compared to W protein indicating the important role played by V protein in viral replication, pathogenesis and immune evasion. However, we speculate the genetic diversity of W proteins could impact the degree of pathogenesis, variable interferon antagonistic activity and the wide host range exhibited by APMV species. Phylogenetically, V proteins of APMVs clustered into three groups similar to the recent classification of APMVs into three new genera while no such pattern could be deciphered in the analysis of W proteins except that strains of same species grouped together. This is the first comprehensive study describing in detail the genetic variations and the molecular evolution of P gene edited, accessory viral proteins of Avian paramyxoviruses.

Newcastle Disease Virus (NDV) Oncolytic Activity in Human Glioma Tumors Is Dependent on CDKN2A-Type I IFN Gene Cluster Codeletion

Glioblastoma (GBM) is the most aggressive and frequent primary brain tumor in adults with a median overall survival of 15 months. Tumor recurrence and poor prognosis are related to cancer stem cells (CSCs), which drive resistance to therapies. A common characteristic in GBM is CDKN2A gene loss, located close to the cluster of type I IFN genes at Ch9p21. Newcastle disease virus (NDV) is an avian paramyxovirus with oncolytic and immunostimulatory properties that has been proposed for the treatment of GBM. We have analyzed the CDKN2A-IFN I gene cluster in 1018 glioma tumors and evaluated the NDV oncolytic effect in six GBM CSCs ex vivo and in a mouse model. Our results indicate that more than 50% of GBM patients have some IFN deletion. Moreover, GBM susceptibility to NDV is dependent on the loss of the type I IFN. Infection of GBM with an NDV-expressing influenza virus NS1 protein can overcome the resistance to oncolysis by NDV of type I-competent cells. These results highlight the potential of using NDV vectors in antitumor therapies.

PEDV ORF3 Independently Regulates IκB Kinase β-Mediated NF-κB and IFN-β Promoter Activities

The Open Reading Frame 3 (ORF3), an accessory protein of porcine epidemic diarrhea virus (PEDV), has been shown to interact with a myriad of cellular proteins, among which include the IκB kinase β (IKBKB). Here, specific IKBKB domains responsible for ORF3–IKBKB interaction were identified. Dysregulation of NF-κB and Type I interferon (IFN) in the presence of ORF3 was also demonstrated. We showed that while ORF3 was capable of up-regulating IKBKB-meditated NF-κB promoter activity, it surprisingly down-regulated the activation of IKBKB-meditated IFN-β promoter and expression of IFN-β mRNA. When overexpressed, ORF3 could suppress Poly I:C mediated type I IFN production and induction. Finally, we demonstrated that IKBKB- and RIG-I-mediated type I IFN induction by ORF3 resulted in different outcomes. Our study is the first to demonstrate the potential and complex roles of ORF3 in the involvement of aberrant immune signaling as well as in the virus–host interaction.

Antibody Repertoires to the Same Ebola Vaccine Antigen Are Differentially Affected by Vaccine Vectors

Comparative immune response profiling is important for selecting next-generation vaccines. We comprehensively evaluated the antibody responses from a panel of nine respiratory vaccines against Ebola virus (EBOV) derived from human and avian paramyxoviruses expressing EBOV glycoprotein (GP). Most vaccines were protective in guinea pigs but yielded antibody repertoires that differed in proportion targeting key antigenic regions, avidity, neutralizing antibody specificities, and linear epitope preferences. Competition studies with monoclonal antibodies from human survivors revealed that some epitopes in GP targeted for neutralization were vector dependent, while EBOV-neutralizing titers correlated with the response magnitude toward the receptor-binding domain and GP1/GP2 interface epitopes. While an immunogen determines the breadth of antibody response, distinct vaccine vectors can induce qualitatively different responses, affecting protective efficacy. These data suggest that immune correlates of vaccine protection cannot be generalized for all vaccines against the same pathogen, even if they use the exact same immunogen.

Binding of the Duck Tembusu Virus Protease to STING Is Mediated by NS2B and Is Crucial for STING Cleavage and for Impaired Induction of IFN-β

Duck Tembusu virus (DTMUV) is a newly emerged causative agent of avian disease. The protease-dependent immune evasion of flaviviruses has been reported; however, the molecular details of this process are unclear. In this study, we found that DTMUV nonstructural protein 2B-3, a NS2B3 protease, can inhibit IFN-β production. DTMUV NS2B3 inhibited RIG-I-, MDA5-, MAVS-, and STING-directed IFN-β transcription, but not TBK1- and IRF7-mediated induction of IFN-β. Further analysis showed that DTMUV NS2B3 could cleave duck STING (duSTING); the cleavage was dependent on the protease activity of NS2B3. Moreover, the STING cleavage event occurred in a not-strictly-species-specific manner. The scissile bond of duSTING cleaved by NS2B3 was mapped between the R84 and G85 residues. The ability of NS2B3 to reduce duSTING cleavage-resistant mutant-mediated IFN-β, and ISG production was significantly reduced, demonstrating that duSTING cleavage is essential for NS2B3-induced suppression of type I IFN responses. Remarkably, the binding of NS2B3 to duSTING, which is a prerequisite for cleavage, was found to depend on NS2B, but not NS3, the cofactor of the enzyme. Unexpectedly, we found that the region between aa residues 221-225 of duSTING, distal from the site of the scissile bond, was essential for the binding of NS2B3 to duSTING and/or the cleavage of duSTING by NS2B3. Thus, we identified the molecular mechanism by which DTMUV subverts the host innate immunity using its protease. More importantly, our study provides insight into NS2B3-mediated STING cleavage events in general.

Immune Modulation and Immune-Mediated Pathogenesis of Emerging Tickborne Banyangviruses

In the last decade, the emergence of several, novel tickborne viruses have caused significant disease in humans. Of interest are the tickborne banyangviruses: Severe fever with thrombocytopenia syndrome virus (SFTSV), Heartland virus (HRTV), and Guertu virus (GTV). SFTSV and HRTV infection in humans cause viral hemorrhagic fever-like disease leading to mortality rates ranging from 6–30% of the cases. The systemic inflammatory response syndrome (SIRS) associated with SFTSV infection is hypothesized to contribute significantly to pathology seen in patients. Despite the severe disease caused by HRTV and SFTSV, there are no approved therapeutics or vaccines. Investigation of the immune response during and following infection is critical to the generation of fully protective vaccines and/or supportive treatments, and overall understanding of viral immune evasion mechanisms may aid in the development of a new class of therapeutics.

Newcastle disease virus mediated apoptosis and migration inhibition of human oral cancer cells: A probable role of β-catenin and matrix metalloproteinase-7

Cancer cell metastasis and its dissemination are most enigmatic and challenging aspects in the development of its therapeutics. Newcastle disease virus (NDV) is a well-studied avian paramyxovirus frequently isolated from birds and rarely from mammals. Since the first report of its oncolytic property, many NDV strains were studied for its effect in various cancer cells. In the present study, NDV strain Bareilly was characterized for its apoptotic potential and migration inhibition in human oral cancer cells. The NDV mediated apoptosis was confirmed by flow cytometry, DNA laddering, and immunoblotting. Moreover, NDV decreased the mitochondrial membrane potential suggesting an intrinsic pathway of apoptosis in oral cancer cells. NDV infection in oral cancer cells results in migration inhibition by a reduction in levels of MMP-7. MMP-7 is one of the key target genes of β-catenin. While overexpression of MMP-7 reversed the inhibitory effect of NDV mediated migration suggested its possible involvement. Wnt/β-catenin is an essential pathway for cell growth, differentiation, and metastasis. The involvement of the Wnt/β-catenin pathway in NDV infection has never been reported. Our results showed that NDV dysregulates Wnt/β-catenin by down-regulation of p-Akt and p-GSK3β leading to degradation of β-catenin. Furthermore, NDV infection leads to a reduction in cytoplasmic and nuclear levels of β-catenin. The study will provide us with a better insight into the molecular mechanism of NDV mediated oncolysis and the key cellular partners involved in the process.

Regression of solid breast tumours in mice by Newcastle disease virus is associated with production of apoptosis related-cytokines

Background

Different strains of Newcastle disease virus (NDV) worldwide proved to have tumouricidal activity in several types of cancer cells. However, the possible anti-cancer activity of Malaysian NDV AF2240 strain and its mechanism of action remains unknown. The ability of cytokine-related apoptosis-inducing NDV AF2240 to treat breast cancer was investigated in the current study.

Methods

A total of 90 mice were used and divided into 15 groups, each group comprising of 6 mice. Tumour, body weight and mortality of the mice were determined throughout the experiment, to observe the effect of NDV and NDV + tamoxifen treatments on the mice. In addition, the toxic effect of the treatments was determined through liver function test. In order to elucidate the involvement of cytokine production induced by NDV, a total of six cytokines, i.e. IL-6, IFN-γ, MCP-1, IL-10, IL12p70 and TNF-α were measured using cytometric bead array assay (plasma) and enzyme-linked immunosorbent spot (isolated splenocytes).

Results

The results demonstrated that 4 T1 breast cancer cells in allotransplanted mice treated with AF2240 showed a noticeable inhibition of tumour growth and induce apoptotic-related cytokines.

Conclusions

NDV AF2240 suppression of breast tumour growth is associated with induction of apoptotic-related cytokines. It would be important to further investigate the molecular mechanism underlaying cytokines production by Newcastle disease virus.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5516-5) contains supplementary material, which is available to authorized users.

A Novel Chimeric Oncolytic Virus Vector for Improved Safety and Efficacy as a Platform for the Treatment of Hepatocellular Carcinoma

Oncolytic viruses represent an exciting new aspect of the evolving field of cancer immunotherapy. We have engineered a novel hybrid vector comprising vesicular stomatitis virus (VSV) and Newcastle disease virus (NDV), named recombinant VSV-NDV (rVSV-NDV), wherein the VSV backbone is conserved but its glycoprotein has been replaced by the hemagglutinin-neuraminidase (HN) and the modified, hyperfusogenic fusion (F) envelope proteins of recombinant NDV. In comparison to wild-type VSV, which kills cells through a classical cytopathic effect, the recombinant virus is able to induce tumor-specific syncytium formation, allowing efficient cell-to-cell spread of the virus and a rapid onset of immunogenic cell death. Furthermore, the glycoprotein exchange substantially abrogates the off-target effects in brain and liver tissue associated with wild-type VSV, resulting in a markedly enhanced safety profile, even in immune-deficient NOD.CB17-prkdc^scid/NCrCrl (NOD-SCID) mice, which are highly susceptible to wild-type VSV. Although NDV causes severe pathogenicity in its natural avian hosts, the incorporation of the envelope proteins in the chimeric rVSV-NDV vector is avirulent in embryonated chicken eggs. Finally, systemic administration of rVSV-NDV in orthotopic hepatocellular carcinoma (HCC)-bearing immune-competent mice resulted in significant survival prolongation. This strategy, therefore, combines the beneficial properties of the rapidly replicating VSV platform with the highly efficient spread and immunogenic cell death of a fusogenic virus without risking the safety and environmental threats associated with either parental vector. Taking the data together, rVSV-NDV represents an attractive vector platform for clinical translation as a safe and effective oncolytic virus.IMPORTANCE The therapeutic efficacy of oncolytic viral therapy often comes as a tradeoff with safety, such that potent vectors are often associated with toxicity, while safer viruses tend to have attenuated therapeutic effects. Despite promising preclinical data, the development of VSV as a clinical agent has been substantially hampered by the fact that severe neurotoxicity and hepatotoxicity have been observed in rodents and nonhuman primates in response to treatment with wild-type VSV. Although NDV has been shown to have an attractive safety profile in humans and to have promising oncolytic effects, its further development has been severely restricted due to the environmental risks that it poses. The hybrid rVSV-NDV vector, therefore, represents an extremely promising vector platform in that it has been rationally designed to be safe, with respect to both the recipient and the environment, while being simultaneously effective, both through its direct oncolytic actions and through induction of immunogenic cell death.

Newcastle disease virus V protein inhibits apoptosis in DF-1 cells by downregulating TXNL1

Many viral proteins are related to suppressing apoptosis in target cells and are hence beneficial to viral replication. The V protein of Newcastle disease virus (NDV) is one such protein that plays an important role in inhibiting apoptosis in a species-specific manner. However, to date, there have been no reports clarifying the antiapoptotic mechanisms of the V protein. The present study was undertaken to determine the apoptotic potential of the V protein in a chicken embryo fibroblast cell line (DF-1 cell) and to elucidate its molecular mechanisms of action. Here, a yeast two-hybrid system was used to screen the host proteins that interact with the V protein and identified thioredoxin-like protein 1 (TXNL1) as a potential binding partner. Immuno-colocalization of V protein and TXNL1 protein in DF-1 cells further verified the interaction of the two proteins. Through the overexpression of TXNL1 protein and knockdown of TXNL1 protein in DF-1 cells, the effects of NDV replication and cell apoptosis were examined. Cell apoptosis was detected by flow cytometry. The mRNA and protein expression levels of Bax, Bcl-2 and Caspase-3 were detected by quantitative real-time PCR (Q-PCR) and Western blotting. NDV expression was detected by Q-PCR and plaque assay. The results revealed that the TXNL1 protein induced apoptosis and inhibited NDV replication in DF-1 cells. Furthermore, the Western blot and Q-PCR results suggested that TXNL1 induced cell apoptosis through a pathway involving Bcl-2\Bax and Caspase-3. Finally, this work provides insight into the mechanism by which the V protein inhibits apoptosis.

Investigating Functional Roles for Positive Feedback and Cellular Heterogeneity in the Type I Interferon Response to Viral Infection

Secretion of type I interferons (IFN) by infected cells mediates protection against many viruses, but prolonged or excessive type I IFN secretion can lead to immune pathology. A proper type I IFN response must therefore maintain a balance between protection and excessive IFN secretion. It has been widely noted that the type I IFN response is driven by positive feedback and is heterogeneous, with only a fraction of infected cells upregulating IFN expression even in clonal cell lines, but the functional roles of feedback and heterogeneity in balancing protection and excessive IFN secretion are not clear. To investigate the functional roles for feedback and heterogeneity, we constructed a mathematical model coupling IFN and viral dynamics that extends existing mathematical models by accounting for feedback and heterogeneity. We fit our model to five existing datasets, reflecting different experimental systems. Fitting across datasets allowed us to compare the IFN response across the systems and suggested different signatures of feedback and heterogeneity in the different systems. Further, through numerical experiments, we generated hypotheses of functional roles for IFN feedback and heterogeneity consistent with our mathematical model. We hypothesize an inherent tradeoff in the IFN response: a positive feedback loop prevents excessive IFN secretion, but also makes the IFN response vulnerable to viral antagonism. We hypothesize that cellular heterogeneity of the IFN response functions to protect the feedback loop from viral antagonism. Verification of our hypotheses will require further experimental studies. Our work provides a basis for analyzing the type I IFN response across systems.

Newcastle Disease Virus V Protein Promotes Viral Replication in HeLa Cells through the Activation of MEK/ERK Signaling

Newcastle disease virus (NDV) can infect a wide range of domestic and wild bird species. The non-structural V protein of NDV plays an important role in antagonizing innate host defenses to facilitate viral replication. However, there is a lack of knowledge related to the mechanisms through which the V protein regulates viral replication. The extracellular signal-regulated kinase (ERK) signaling pathway in the host is involved in a variety of functions and is activated by several stimuli, including viral replication. In this study, we show that both the lentogenic strain, La Sota, and the velogenic strain, F48E9, of NDV activate the mitogen-activated protein kinase (MEK)/ERK signaling pathway. The pharmacological inhibition of ERK1/2 phosphorylation using the highly selective inhibitors U0126 and SCH772984 resulted in the reduced levels of NDV RNA in cells and virus titers in the cell supernatant, which established an important role for the MEK/ERK signaling pathway in NDV replication. Moreover, the overexpression of the V protein in HeLa cells increased the phosphorylation of ERK1/2 and induced the transcriptional changes in the genes downstream of the MEK/ERK signaling pathway. Taken together, our results demonstrate that the V protein is involved in the ERK signaling pathway-mediated promotion of NDV replication and thus, can be investigated as a potential antiviral target.

Combining Vascular Normalization with an Oncolytic Virus Enhances Immunotherapy in a Preclinical Model of Advanced-Stage Ovarian Cancer

PURPOSE

Intravenous delivery of oncolytic viruses often leads to tumor vascular shutdown, resulting in decreased tumor perfusion and elevated tumor hypoxia. We hypothesized that using 3TSR to normalize tumor vasculature prior to administration of an oncolytic Newcastle disease virus (NDV) would enhance virus delivery and trafficking of immunologic cell subsets to the tumor core, resulting in systemically enhanced immunotherapy and regression of advanced-stage epithelial ovarian cancer (EOC).

EXPERIMENTAL DESIGN

Using an orthotopic, syngeneic mouse model of advanced-stage EOC, we pretreated mice with 3TSR (4 mg/kg per day) alone or followed by combination with fusogenic NDV(F3aa) (1.0 × 10⁸ plaque-forming units).

RESULTS

Treatment with 3TSR normalized tumor vasculature, enhanced blood perfusion of primary EOC tumors, and induced disease regression. Animals treated with combination therapy had the greatest reduction in primary tumor mass, ascites accumulation, and secondary lesions (50% of mice were completely devoid of peritoneal metastases). Combining 3TSR + NDV(F3aa) led to enhanced trafficking of immunologic cells into the primary tumor core.

CONCLUSIONS

We have shown, for the first time, that NDV, like other oncolytic viruses, is a potent mediator of acute vascular shutdown and that preventing this through vascular normalization can promote regression in a preclinical model of advanced-stage ovarian cancer. This challenges the current focus on induction of intravascular thrombosis as a requisite for successful oncolytic virotherapy.See related commentary by Bykov and Zamarin, p. 1446.

Newcastle Disease Virus V Protein Inhibits Cell Apoptosis and Promotes Viral Replication by Targeting CacyBP/SIP

Newcastle disease virus (NDV) has been classified by the World Organization for Animal Health (OIE) as a notable disease-causing virus, and this virus has the ability to infect a wide range of birds. V protein is a non-structural protein of NDV. V protein has been reported to inhibit cell apoptosis (Park et al., 2003a) and promote viral replication (Huang et al., 2003), however, the mechanisms of action of V protein have not been elucidated. In the present study, a yeast two-hybrid screen was performed, and V protein was found to interact with the CacyBP/SIP protein. The results of co-immunoprecipitation and immuno-colocalization assays confirmed the interaction between V protein and CacyBP/SIP. The results of quantitative-PCR and viral plaque assays showed that overexpression of CacyBP/SIP inhibited viral replication in DF-1 cells. Overexpression of CacyBP/SIP in DF-1 cells induced caspase3-dependent apoptosis. The effect of knocking down CacyBP/SIP by siRNA was the opposite of that observed upon overexpression. Moreover, it is known that NDV induces cell apoptosis via multiple caspase-dependent pathways. Furthermore, V protein inhibited cell apoptosis and downregulated CacyBP/SIP expression in DF-1 cells. Taken together, the findings of the current study indicate that V protein interacts with CacyBP/SIP, thereby regulating cell apoptosis and viral replication.

Production, characterization, and epitope mapping of a monoclonal antibody against genotype VII Newcastle disease virus V protein

Newcastle disease virus (NDV) V protein is crucial for viral interferon (IFN) antagonism and virulence, determining its host range restriction. However, little information is available on the B cell epitopes of V protein and the subcellular movement of V protein in the process of NDV infection. In this study, the monoclonal antibody (mAb) clone 3D7 against genotype VII NDV V protein was generated by immunizing mice with a purified recombinant His-tagged carboxyl-terminal domain (CTD) region of V protein. Fine epitope mapping analysis and B-cell epitope prediction indicated that mAb 3D7 recognized a linear epitope ¹⁵²RGPAELWK¹⁵⁹, which is located in the V protein CTD region. Sequence alignment showed that the mAb clone 3D7-recognized epitope is highly conserved among Class II genotype VII NDV strains, but not among other genotypes, suggesting it could serve as a genetic marker to differentiate NDV genotypes. Furthermore, the movement of V protein during NDV replication in infected cells were determined by using this mAb. It was found that V protein localized around the nucleus during virus replication. The establishment of V protein-specific mAb and identification of its epitope extend our understanding of the antigenic characteristics of V protein and provide a basis for the development of epitope-based diagnostic assays.

Fusogenic Viruses in Oncolytic Immunotherapy

Oncolytic viruses are under intense development and have earned their place among the novel class of cancer immunotherapeutics that are changing the face of cancer therapy. Their ability to specifically infect and efficiently kill tumor cells, while breaking immune tolerance and mediating immune responses directed against the tumor, make oncolytic viruses highly attractive candidates for immunotherapy. Increasing evidence indicates that a subclass of oncolytic viruses, which encodes for fusion proteins, could outperform non-fusogenic viruses, both in their direct oncolytic potential, as well as their immune-stimulatory properties. Tumor cell infection with these viruses leads to characteristic syncytia formation and cell death due to fusion, as infected cells become fused with neighboring cells, which promotes intratumoral spread of the infection and releases additional immunogenic signals. In this review, we discuss the potential of fusogenic oncolytic viruses as optimal candidates to enhance immunotherapy and initiate broad antitumor responses. We provide an overview of the cytopathic mechanism of syncytia formation through viral-mediated expression of fusion proteins, either endogenous or engineered, and their benefits for cancer therapy. Growing evidence indicates that fusogenicity could be an important feature to consider in the design of optimal oncolytic virus platforms for combinatorial oncolytic immunotherapy.

RIP1 is a central signaling protein in regulation of TNF-α/TRAIL mediated apoptosis and necroptosis during Newcastle disease virus infection

Newcastle disease virus (NDV) is an oncolytic virus which selectively replicates in tumor cells and exerts anti-tumor cytotoxic activity by promoting cell death. In this study, we focus on characterization of the underlying mechanisms of NDV-induced cell death in HeLa cells. We find that NDV Herts/33 strain triggers both extrinsic and intrinsic apoptosis at late infection times. The activation of NF-кB pathway and subsequent up-regulation of TNF-α/TRAIL initiates extrinsic apoptosis, leading to activation of caspase 8 and cleavage of Bid into tBid. tBid transmits the extrinsic apoptotic signals to mitochondria and mediates intrinsic apoptosis, which is hallmarked by cleavage of caspase 9. Moreover, RIP1 is cleaved into RIP1-N and RIP1-C at D324 by caspase 8, and this cleavage promotes apoptosis. Surprisingly, over expression of RIP1 reduces apoptosis and depletion of RIP1 promotes apoptosis, suggesting full length RIP1 is anti-apoptotic. Moreover, necroptosis hallmark protein MLKL is activated by phosphorylation at 12-24 h.p.i., and RIP1 regulates the level of phosphor-MLKL. Immunostaining shows that RIP1 aggregates to stress granules (SGs) at 8-24 h.p.i., and phosphor-MLKL is also recruited to SGs, instead of migrating to plasma membrane to exert its necrotic function. Immunoprecipitation study demonstrates that RIP1 bind to phosphor-MLKL, and depletion of RIP1 reduces the aggregation of MLKL to SGs, suggesting that RIP1 recruits MLKL to SGs. Altogether, NDV infection initiates extrinsic apoptosis via activation of NF-кB and secretion of TNF-α/TRAIL. Activation of caspase 8 by TNF-α/TRAIL and subsequent cleavage of Bid and RIP1 transmit the death signals to mitochondria. Meanwhile, virus subverts the host defensive necroptosis via recruiting phosphor-MLKL by RIP1 to SGs. Thus, RIP1 is a central signaling protein in regulation of apoptosis and necroptosis during NDV infection.

Newcastle disease virus vectored vaccines as bivalent or antigen delivery vaccines

Recent advances in reverse genetics techniques make it possible to manipulate the genome of RNA viruses such as Newcastle disease virus (NDV). Several NDV vaccine strains have been used as vaccine vectors in poultry, mammals, and humans to express antigens of different pathogens. The safety, immunogenicity, and protective efficacy of these NDV-vectored vaccines have been evaluated in pre-clinical and clinical studies. The vaccines are safe in mammals, humans, and poultry. Bivalent NDV-vectored vaccines against pathogens of economic importance to the poultry industry have been developed. These bivalent vaccines confer solid protective immunity against NDV and other foreign antigens. In most cases, NDV-vectored vaccines induce strong local and systemic immune responses against the target foreign antigen. This review summarizes the development of NDV-vectored vaccines and their potential use as a base for designing other effective vaccines for veterinary and human use.

RIP1 is a central signaling protein in regulation of TNF-α/TRAIL mediated apoptosis and necroptosis during Newcastle disease virus infection

Newcastle disease virus (NDV) is an oncolytic virus which selectively replicates in tumor cells and exerts anti-tumor cytotoxic activity by promoting cell death. In this study, we focus on characterization of the underlying mechanisms of NDV-induced cell death in HeLa cells. We find that NDV Herts/33 strain triggers both extrinsic and intrinsic apoptosis at late infection times. The activation of NF-кB pathway and subsequent up-regulation of TNF-α/TRAIL initiates extrinsic apoptosis, leading to activation of caspase 8 and cleavage of Bid into tBid. tBid transmits the extrinsic apoptotic signals to mitochondria and mediates intrinsic apoptosis, which is hallmarked by cleavage of caspase 9. Moreover, RIP1 is cleaved into RIP1-N and RIP1-C at D324 by caspase 8, and this cleavage promotes apoptosis. Surprisingly, over expression of RIP1 reduces apoptosis and depletion of RIP1 promotes apoptosis, suggesting full length RIP1 is anti-apoptotic. Moreover, necroptosis hallmark protein MLKL is activated by phosphorylation at 12-24 h.p.i., and RIP1 regulates the level of phosphor-MLKL. Immunostaining shows that RIP1 aggregates to stress granules (SGs) at 8-24 h.p.i., and phosphor-MLKL is also recruited to SGs, instead of migrating to plasma membrane to exert its necrotic function. Immunoprecipitation study demonstrates that RIP1 bind to phosphor-MLKL, and depletion of RIP1 reduces the aggregation of MLKL to SGs, suggesting that RIP1 recruits MLKL to SGs. Altogether, NDV infection initiates extrinsic apoptosis via activation of NF-кB and secretion of TNF-α/TRAIL. Activation of caspase 8 by TNF-α/TRAIL and subsequent cleavage of Bid and RIP1 transmit the death signals to mitochondria. Meanwhile, virus subverts the host defensive necroptosis via recruiting phosphor-MLKL by RIP1 to SGs. Thus, RIP1 is a central signaling protein in regulation of apoptosis and necroptosis during NDV infection.

Review: Oncolytic virotherapy, updates and future directions

Oncolytic viruses (OVs) are viral strains that can infect and kill malignant cells while spare their normal counterparts. OVs can access cells through binding to receptors on their surface or through fusion with the plasma membrane and establish a lytic cycle in tumors, while leaving normal tissue essentially unharmed. Multiple viruses have been investigated in humans for the past century. IMLYGIC™ (T-VEC/Talimogene Laherparepvec), a genetically engineered Herpes Simplex Virus, is the first OV approved for use in the United States and the European Union for patients with locally advanced or non-resectable melanoma.

Although OVs have a favorable toxicity profile and are impressively active anticancer agents in vitro and in vivo the majority of OVs have limited clinical efficacy as a single agent. While a virus-induced antitumor immune response can enhance oncolysis, when OVs are used systemically, the antiviral immune response can prevent the virus reaching the tumor tissue and having a therapeutic effect. Intratumoral administration can provide direct access to tumor tissue and be beneficial in reducing side effects.

Immune checkpoint stimulation in tumor tissue has been noted after OV therapy and can be a natural response to viral-induced oncolysis. Also for immune checkpoint inhibition to be effective in treating cancer, an immune response to tumor neoantigens and an inflamed tumor microenvironment are required, both of which treatment with an OV may provide. Therefore, direct and indirect mechanisms of tumor killing provide rationale for clinical trials investigating the combination of OVs other forms of cancer therapy, including immune checkpoint inhibition.

Immunobiology of Newcastle Disease Virus and Its Use for Prophylactic Vaccination in Poultry and as Adjuvant for Therapeutic Vaccination in Cancer Patients

Newcastle disease (ND) is one of the most important diseases of poultry worldwide. In the last decades, molecular research has gained a lot of new information about its causative agent, newcastledisease virus (NDV). In poultry industry, certain strains of NDV have been used for preventive vaccination for more than 60 years. NDV has also been applied to cancer patients with beneficial effects for about 50 years, but this is less well known. The molecular basis for these differential effects of NDV in birds and man have been elucidated in the last decades and are explained in this review. The anti-neoplastic and immune-stimulatory properties in non-permissive hosts such as mouse and man have to do with the strong type I interferon responses induced in these foreign species. Additionally, NDV has the potential to break various types of tumor resistances and also to affect liver fibrosis. A main section is devoted to the benefits of clinical application of NDV and NDV-based vaccines to cancer patients. Reverse genetics technology allowed developing NDV into a vector suitable for gene therapy. Examples will be provided in which genetically engineered NDV is being used successfully as vector against new emerging viruses.

Replication and Oncolytic Activity of an Avian Orthoreovirus in Human Hepatocellular Carcinoma Cells

Oncolytic viruses are cancer therapeutics with promising outcomes in pre-clinical and clinical settings. Animal viruses have the possibility to avoid pre-existing immunity in humans, while being safe and immunostimulatory. We isolated an avian orthoreovirus (ARV-PB1), and tested it against a panel of hepatocellular carcinoma cells. We found that ARV-PB1 replicated well and induced strong cytopathic effects. It was determined that one mechanism of cell death was through syncytia formation, resulting in apoptosis and induction of interferon stimulated genes (ISGs). As hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma worldwide, we investigated the effect of ARV-PB1 against cells already infected with this virus. Both HCV replicon-containing and infected cells supported ARV-PB1 replication and underwent cytolysis. Finally, we generated in silico models to compare the structures of human reovirus- and ARV-PB1-derived S1 proteins, which are the primary targets of neutralizing antibodies. Tertiary alignments confirmed that ARV-PB1 differs from its human homolog, suggesting that immunity to human reoviruses would not be a barrier to its use. Therefore, ARV-PB1 can potentially expand the repertoire of oncolytic viruses for treatment of human hepatocellular carcinoma and other malignancies.