DEAD-Box RNA Helicase DDX3X, an Intrinsic Host Factor, Regulates Oncolytic Myxoma Virus Replication in Human Cancer Cells

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Description
Myxoma virus (MYXV), a Leporipoxvirus, is being developed as an oncolytic agent against various types of human cancers. It successfully infects and has oncolytic effects on cancer cells while remaining nonpathogenic to normal human cells and all other non-leporid species.…

Myxoma virus (MYXV), a Leporipoxvirus, is being developed as an oncolytic agent against various types of human cancers. It successfully infects and has oncolytic effects on cancer cells while remaining nonpathogenic to normal human cells and all other non-leporid species. To develop virus constructs and maximize their effectiveness against cancer cells, the interaction between virus and host should be well characterized. DEAD-box RNA helicase DDX3 was previously identified as an intrinsic host factor that regulates MYXV replication in human cancer cell lines. Here, it is reported that transient knockdown of DDX3 in human cancer cells significantly enhances MYXV replication and progeny virus production. In uninfected cells, DDX3 localizes throughout the cytoplasm of human cells; however, in the MYXV-infected cells, DDX3 localizes to the perinuclear region of the cells and forms granule-like particles. It is further demonstrated that DDX3 is likely enhancing the type-1 interferon (IFN) production as the expression of the cytokine is decreased when DDX3 is knocked down during MYXV virus infection. Thus, the absence of DDX3 significantly enhanced myxoma virus spread by reducing the production of type-1 IFN and IFN-mediated signaling. These results suggest that DDX3 is a potential cellular target for enhancing the oncolytic activity of MYXV in human cancers.
Date Created
2024
Agent

Z-DNA Binding Protein 1 (ZBP1)-Mediated Cell Death During Infection by Diverse RNA Viruses is Dependent on the Zα2 Domain

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Description
Z-DNA binding protein 1 (ZBP1) is an interferon-inducible protein that plays a crucial role in antiviral defense by recognizing Z-form nucleic acid (Z-NA), a left-handed conformer of double-stranded DNA/RNA. When ZBP1 binds to Z-NA, it can trigger programmed cell death…

Z-DNA binding protein 1 (ZBP1) is an interferon-inducible protein that plays a crucial role in antiviral defense by recognizing Z-form nucleic acid (Z-NA), a left-handed conformer of double-stranded DNA/RNA. When ZBP1 binds to Z-NA, it can trigger programmed cell death pathways, including apoptosis and necroptosis, in collaboration with receptor interacting protein kinases 1 and 3 (RIPK1 and RIPK3). Z-NA positive viruses including poxviruses and influenza A virus (IAV) activate ZBP1-dependent cell death during replication. Little is known whether ZBP1 plays any role during Z-NA negative virus infection. Doxycycline-inducible A549 ACE2 Tet-On cells were constructed to express ZBP1 and were infected with Z-NA negative viruses. ZBP1-expressing cells infected with Sindbis virus (SINV), La Crosse virus (LACV), Vesicular stomatitis virus (VSV) and human coronavirus OC43 (hCoV-OC43) underwent extensive cell death, which could be rescued by a caspase inhibitor but not by JAK1/2 or RIPK1 kinase inhibitors. However, cell death was not observed upon Zika virus (ZIKV), Encephalomyocarditis virus (EMCV), Chikungunya virus (CHKV) or human coronavirus 229E (hCoV-229E) infection. ZBP1 expression did not impact the replication of all tested viruses. In addition, ZBP1-mediated cell death during infection depends on the Zα2 and RHIM1 domains and partially on the C-terminal domain. These findings suggest that Z-NA can be detected by the Zα2 domain to initiate cell death pathways during infection with some Z-NA negative viruses and that the RHIM1/C-terminal domains are necessary for ZBP1-induced cell death. Further research is needed to determine the Z-NA ligand and the precise mechanism of ZBP1-mediated antiviral responses and how they can be exploited for the development of novel antiviral therapies.
Date Created
2023
Agent

Determining the Role of Innate Immune Elements on RNA Viral Replication and Understanding Factors that Impact Adaptive T cell Anti-tumoral Activity Against Metastatic Osteosarcoma (mOS)

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Description
The innate immune system serves as an immediate response to pathogenic infection and an informant to the adaptive immune system. The 2′,5′-oligoadenylate (2-5A) synthetase (OAS)–RNase-L system is a component of the innate immune system induced by interferons (IFNs) and serves…

The innate immune system serves as an immediate response to pathogenic infection and an informant to the adaptive immune system. The 2′,5′-oligoadenylate (2-5A) synthetase (OAS)–RNase-L system is a component of the innate immune system induced by interferons (IFNs) and serves to eliminate viral infections. In humans, three enzymatically active OAS proteins exist, OAS1, OAS2, and OAS3. Recent evidence suggests variations in cellular localization of OAS proteins may influence the impact and influence of those proteins on viral replication. However, viral suppression mechanisms involving specific OAS proteins are still unclear for most viruses. Here, I overexpress different isoforms of OAS and determined that though viruses within the same family have similar replication strategies, the extent to which each OAS protein impacts viral replication for Flaviviruses, and Alphaviruses varies. In contrast to the innate immune system, the adaptive immune system provides specific and long-lived immune responses. In the context of cancer, T cells have been shown to play a prominent role in tumor regression. It has previously been demonstrated that administration α-CTLA-4/α-PD-L1 immune checkpoint blockade (ICB) to mice inoculated with a K7M2 metastatic osteosarcoma (mOS) cell line resulted in ~50% survival. Here, I sought to determine biological differences among murine responders and non-responders to ICB for mOS to understand better what factors could increase ICB efficacy. A prospective culprit is a variance in circulating antibodies (Abs). I have shown that sera from mice, before inoculation with mOS or ICB, display distinct differences in Ab repertoire between responders and non-responders, suggesting the presence or absence of particular Abs may influence the outcome of ICB. Recent studies have also shown that malleable environmental factors, such as differences in microbiome composition, can yield subsequent changes in circulating Abs. Strong associations have been made between host-microbiome interactions and their effects on health. Here, I study potential associations of microbiome-mediated impacts on ICB efficacy for mOS. Additionally, I sought to determine potential changes in T-cellular response to mOS due to modulations in microbiome composition and showed that ICB efficacy can change in conjunction with microbiome composition changes in a murine model.
Date Created
2023
Agent

Gastrointestinal SARS-CoV-2 Viral RNA Shedding and Viability

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Description

On March 11th, COVID-19 was declared a pandemic by the World Health Organization. The ensuing months saw an extensive allocation of resources toward combating the virus and the development of a vaccine. Despite extensive research on SARS-CoV-2, there remains little…

On March 11th, COVID-19 was declared a pandemic by the World Health Organization. The ensuing months saw an extensive allocation of resources toward combating the virus and the development of a vaccine. Despite extensive research on SARS-CoV-2, there remains little information regarding the implications of SARS-CoV-2 gastrointestinal shedding on COVID-19 disease. It is hypothesized that SARS-CoV-2 RNA is shed in the stool for up to several weeks and that viral protein persists in the GI tract. This study also explored calprotectin and zonulin levels, markers of inflammation, and intestinal permeability, respectively, to assess if increased viral shedding is associated with elevated levels of either. This study utilized RT-qPCR assays to confirm the presence of viral RNA. Subsequently, RT-qPCR positive samples were heat-inactivated and SARS-CoV-2 spike detection enzyme-linked immunosorbent assay (ELISA) was used to ascertain viral protein shedding. Additional ELISA was performed to assess zonulin and calprotectin levels. Results indicated that 30 of the 758 unique samples were confirmed SARS-CoV-2 positive by RT-qPCR. Spike protein was ultimately not detected by ELISA. Additionally, no significant increase in zonulin was observed in patient samples when comparing RT-qPCR positive and negative Samples. A notable upwards trend approaching significance in calprotectin levels existed for patients who tested positive for SARS-CoV-2 by RT-qPCR, though, it was found that no correlation existed between SARS-CoV-2 copy number and calprotectin levels. Understanding the interaction between SARS-CoV-2 and the GI tract may therefore have significant clinical implications and this study demonstrates the need for additional studies to garner a more comprehensive understanding.

Date Created
2022-05
Agent

The Potential of Virus-Like Particles (VLPs) as an Effective Vaccine Candidate for the COVID-19 Vaccine: Review

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Description

Virus-like particles (VLPs) are optimum candidates for creating vaccines, as they are highly flexible, adaptable, safe, and similar to the structural proteins of the target cells. The COVID 19 pandemic has increased the need to create effective and safe vaccines…

Virus-like particles (VLPs) are optimum candidates for creating vaccines, as they are highly flexible, adaptable, safe, and similar to the structural proteins of the target cells. The COVID 19 pandemic has increased the need to create effective and safe vaccines that can be mass produced to stop the spread of COVID-19. Till now, various types of vaccine platforms have been utilized to create COVID-19 vaccines, each with unique characteristics and techniques. It is essential to use robust vaccine platforms that can deliver optimum results in a short period of time, with minimal risks. The structural proteins found in SARS-CoV-2, such as Spike (S) protein have been widely targeted to induce antibody response, also called a humoral response, which is a part of acquired immunity. The other structural proteins such as M (membrane) and E (envelope) can also be used as targets for antibodies. The S2 and glycoprotein (S full) can be used to induce an efficient IgG response. Therefore, the incorporation of structural proteins into VLPs can prove to be useful. Furthermore, double mosaic VLPs employs double epitopes, which can effectively cover the distances between the S proteins, thus optimizing the B cell activation process. This review describes the various developments that have taken place in the field of VLPs and more specifically, with regards to developing VLP vaccines against the SARS-CoV-2 virus.

Date Created
2022-05
Agent
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