Microbiome and Virome Models of Human Health and Disease

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Description
The human gut microbiome is associated with health outcomes including gastrointestinal and metabolic health, autoimmune disease and cancer. However, the role of the microbiome in many disease processes, including in the preterm gastrointestinal tract and female genital tract, has yet

The human gut microbiome is associated with health outcomes including gastrointestinal and metabolic health, autoimmune disease and cancer. However, the role of the microbiome in many disease processes, including in the preterm gastrointestinal tract and female genital tract, has yet to be defined. Further, the diverse community of viruses within the microbiome (the virome) is understudied compared to bacteria. Here, I examine the microbiome and virome in specific disease models that are poorly understood: necrotizing enterocolitis (NEC), discordant HIV shedding in women living with HIV (WHLIV), female genital tract inflammation and gammaherpesvirus infection. Specifically, I examined the gut virome longitudinally in a cohort of preterm infants at risk for NEC; the female genital tract (FGT) microbiome and virome longitudinally in a cohort of WLHIV from Lima, Peru; the FGT virome in women from Phoenix, Arizona with differing levels of genital inflammation and different microbiome compositions; and the gut microbiome in murine gammaherpesvirus 68 (MHV68) infection. Further, I contributed to research responding to the spread of SARS-CoV-2 in Arizona. I found that 1) gut virome beta diversity decreased before NEC onset in preterm infants, suggesting a role for the virome in NEC; 2) FGT microbiome instability was associated with discordant HIV shedding, while FGT virome composition changed in association with ART duration and immune recovery; 3) FGT virome composition was associated with inflammation and microbiome composition; and 4) MHV68 infection outcomes were independent of microbiome perturbation, which may reflect environmental influences. The results of this research advance understanding of the microbiome and virome in these specific disease processes, and support further investigation of the microbiome and virome in preterm infant gastrointestinal health and FGT health, as well as environmental effects in microbiome research.
Date Created
2024
Agent

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

Longitudinal Quantification of Neutralizing Antibodies and T cell Responses to COVID-19 mRNA Vaccines

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Description
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative pathogen of Coronavirus Disease 2019 (COVID-19). Successful vaccination aims to elicit neutralizing antibodies (NAbs) which inhibit viral infection. Traditional NAb quantification methods (neutralization assays) are labor-intensive and expensive, with limited practicality

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative pathogen of Coronavirus Disease 2019 (COVID-19). Successful vaccination aims to elicit neutralizing antibodies (NAbs) which inhibit viral infection. Traditional NAb quantification methods (neutralization assays) are labor-intensive and expensive, with limited practicality for routine use (e.g. monitoring vaccination response). Thus, a rapid (10-minute) lateral flow assay (LFA) for quantification of SARS-CoV-2 NAbs was developed. Using the NAb LFA, an 18-month longitudinal study assessing monthly NAb titers was conducted in a cohort of over 500 COVID-19 mRNA vaccine recipients. Three NAb response groups were identified: vaccine strong responders (VSRs), moderate responders (VMRs), and poor responders (VPRs). VSRs generated high and durable NAb titers. VMRs initially generated high NAb titers but showed more rapid waning with time post-vaccination. Finally, VPRs rarely generated NAb titers ≥1:160, even after 3rd dose. Although strong humoral responses correlate with vaccine effectiveness, viral-specific CD4+ and CD8+ T cells are critical for long-term protection. Discordant phenotypes of viral-specific CD8+ and CD4+CXCR5+ T follicular helper (cTfh) cells have recently been associated with differential NAb responses. The second portion of this dissertation was to investigate whether/how SARS-CoV-2 T cell responses differ in individuals with impaired NAb titers following mRNA vaccination. Thus, phenotypic and functional characterization of T cell activation across NAb response groups was conducted. It was hypothesized that VPRs would exhibit discordant SARS-CoV-2 T cell activation and altered cTfh phenotypes. Peripheral blood mononuclear cells were isolated from VPRs, VMRs, VSRs, naturally infected, and normal donors. SARS-CoV-2 responsive T cells were characterized using in vitro activation induced marker assays, multicolor flow cytometry, and multiplex cytokine analysis. Further, CXCR5+ cTfh were examined for chemokine receptor expression (CCR6 and CXCR3). Results demonstrated that despite differential NAb responses, activation of SARS-CoV-2 responsive CD4+ and CD8+ T cells was comparable across NAb groups. However, double-positive CD4+CD8+, CD8low, and activated CD4+CXCR5+CCR6-CXCR3+ (Tfh1-like) T cells were expanded in VPRs compared to VMR and VSRs. Interestingly, a unique population of CD8+CXCR5+ T cells was also expanded in VPRs. These novel findings may aid in identification of individuals with impaired or altered immune responses to COVID-19 mRNA vaccination.
Date Created
2023
Agent

The Effects of Selinexor Concentration and Time on the Myxoma Virus

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Description
Cancer is one of the leading causes of death, globally, with an estimated 9.6 million deaths in 2018, according to the World Health Organization. However, this is not the only impact cancer has on affected individuals, as death rates only

Cancer is one of the leading causes of death, globally, with an estimated 9.6 million deaths in 2018, according to the World Health Organization. However, this is not the only impact cancer has on affected individuals, as death rates only capture the mortality of cancer, there are still detrimental effects cancer has on quality of life. Newer therapies for cancer attempt to circumvent these unwanted detriments, such as hormone therapy, stem cell transplants, targeted therapy, etc.3. One such novel therapy being virotherapy, which is the subject of this study. This study follows the observations of the myxoma virus (MYXV), a prototypic poxvirus which belongs to the Leporipoxvirus genus of the Poxviridae family. This method allows larger particles to enter host cells through the process of overriding host cell endocytosis pathways, with a few exceptions. Interestingly, research has shown that MYXV has been able to infect multiple types of tumor cells of non-rabbit species both in vitro and in vivo, in not only humans but murine, rodent, species as well. This allows MYXV to pose as a potential virotherapy for human cancer cells. McFadden research lab has been researching the role of the exportin 1 protein (XPO1), also known as the chromosome maintenance region-1 (CRM-1). It is suspected that the XPO1 pathway may be one of the evasion mechanisms that MYXV utilizes as an antiviral response. KPT-330 (Selinexor) is a selective inhibitor of nuclear transport (SINE) drug that was designed as the first-in-human oral FDA approved cancer treatment. It has been shown effectiveness in inhibiting XPO1 in multiple lines of cancer cells, such as the Lewis Lung Carcinoma (LLC1) cells researched in this study. McFadden research lab has been examining the effects of various Selinexor concentrations along with different multiplicities of infection (MOIs) of MYXV to determine the best combination that can be used to reduce tumor size at the highest effectiveness. Overall, Selinexor is not increasing cell killing through a synergistic means, but rather simply by increasing the ability of MYXV to infect and spread in LLC1 cells. This then causes increased cell killing given that more LLC1 cells are penetrated by the OV and “suffocated” by the prevention of exporting essential proteins from the nucleus to their respectively critical final destinations in the cancer cells.
Date Created
2022-05
Agent

Comparison of Antibody Responses to Myxoma Virus Inactivated Using Different Methods

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Description

In this study, we investigated the inactivation of wild-type vMyx-GFP (MYXV) using different methods. Assays were performed in vitro to test the following inactivation methods: heat, longwave UV only, longwave UV with psoralen (P + LWUV), and psoralen (P) only.

In this study, we investigated the inactivation of wild-type vMyx-GFP (MYXV) using different methods. Assays were performed in vitro to test the following inactivation methods: heat, longwave UV only, longwave UV with psoralen (P + LWUV), and psoralen (P) only. In vitro assays demonstrated that the psoralen alone treatment did not cause any inactivation. These results showed that effective inactivation using psoralen was likely reliant on subsequent UV irradiation, creating a synergistic effect. Additionally, the UV and P + LWUV treatment demonstrated inactivation of MYXV, although by different mechanisms, as the UV-only treated virus demonstrated background infection, while P + LWUV treated virus did not. In mice, P + LWUV and UV treatment of MYXV demonstrated to be effective inactivation methods and likely preserved the antigenic epitopes of MYXV, allowing for the production of neutralizing antibodies in mice. More research is recommended on the heat treatment of MYXV as neutralizing antibodies were not observed, possibly due to the treatment denaturing antigenic epitopes or needing more booster injections to reach the threshold antibody concentration for protection. Furthermore, we demonstrated that the intraperitoneal (IP) injection of inactivated MYXV was superior to the subcutaneous injection in eliciting a strong immune response. The increased neutralizing antibodies observed after IP injection could be due to the advantage that the IP route has of reaching lymphoid tissue faster.

Date Created
2021-05
Agent

Comparison of Antibody Responses to Myxoma Virus Inactivated Using Different Methods

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Description

In this study, we investigated the inactivation of wild-type vMyx-GFP (MYXV) using different methods. Assays were performed in vitro to test the following inactivation methods: heat, longwave UV only, longwave UV with psoralen (P + LWUV), and psoralen (P) only.

In this study, we investigated the inactivation of wild-type vMyx-GFP (MYXV) using different methods. Assays were performed in vitro to test the following inactivation methods: heat, longwave UV only, longwave UV with psoralen (P + LWUV), and psoralen (P) only. In vitro assays demonstrated that the psoralen alone treatment did not cause any inactivation. These results showed that effective inactivation using psoralen was likely reliant on subsequent UV irradiation, creating a synergistic effect. Additionally, the UV and P + LWUV treatments demonstrated inactivation of MYXV, although by different mechanisms, as the UV-only treated virus demonstrated background infection, while P + LWUV treated virus did not. In mice, P + LWUV and UV treatment of MYXV demonstrated effective inactivation methods and likely preserved the antigenic epitopes of MYXV, allowing for the production of neutralizing antibodies in mice. More research may need to be conducted on the heat treatment of MYXV as neutralizing antibodies were not observed, possibly due to the treatment denaturing antigenic epitopes or needing more booster injections to reach the threshold antibody concentration for protection. Furthermore, we demonstrated that the intraperitoneal (IP) injection of inactivated MYXV was superior to the subcutaneous injection in eliciting a strong immune response. The increased neutralizing antibodies observed after IP injection could be due to the advantage that the IP route has of reaching lymphoid tissue faster.

Date Created
2021-05
Agent

Identification of Host DEAD-Box RNA Helicases That Regulate Cellular Tropism of Oncolytic Myxoma Virus in Human Cancer Cells

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Description

Myxoma virus (MYXV), a Leporipoxvirus, is being developed as an oncolytic virotherapeutic for the treatment of a variety of human cancers. MYXV tropism for human cancer cells is largely mediated by intracellular signaling networks that regulate viral replication or innate

Myxoma virus (MYXV), a Leporipoxvirus, is being developed as an oncolytic virotherapeutic for the treatment of a variety of human cancers. MYXV tropism for human cancer cells is largely mediated by intracellular signaling networks that regulate viral replication or innate antiviral response pathways. Thus, MYXV is fully or partially permissive for the majority of human cancer cells that harbor defects in antiviral signaling, but a minority are nonpermissive because the virus infection aborts before its completion. To identify host factors relevant for MYXV tropism in human cancer cells, we performed a small interfering RNA (siRNA) library screen targeting the 58 human DEAD-box RNA helicases in two permissive human cancer cells (HeLa and A549), one semi-permissive (786-0), and one nonpermissive cell line (PANC-1). Five host RNA helicases (DDX3X, DDX5, DHX9, DHX37, DDX52) were inhibitory for optimal replication and thus classified as anti-viral, while three other cellular RNA helicases (DHX29, DHX35, RIG-I) were identified as pro-viral or pro-cellular because knockdown consistently reduced MYXV replication and/or required metabolic functions of permissive cancer cells. These findings suggest that replication of MYXV, and likely all poxviruses, is dramatically regulated positively and negatively by multiple host DEAD-box RNA helicases.

Date Created
2017-11-16
Agent

Myxoma Virus dsRNA Binding Protein M029 Inhibits the Type I IFN‐Induced Antiviral State in a Highly Species‐Specific Fashion

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Description

Myxoma virus (MYXV) is Leporipoxvirus that possesses a specific rabbit‐restricted host tropism but exhibits a much broader cellular host range in cultured cells. MYXV is able to efficiently block all aspects of the type I interferon (IFN)‐induced antiviral state in

Myxoma virus (MYXV) is Leporipoxvirus that possesses a specific rabbit‐restricted host tropism but exhibits a much broader cellular host range in cultured cells. MYXV is able to efficiently block all aspects of the type I interferon (IFN)‐induced antiviral state in rabbit cells, partially in human cells and very poorly in mouse cells. The mechanism(s) of this species‐specific inhibition of type I IFN‐induced antiviral state is not well understood. Here we demonstrate that MYXV encoded protein M029, a truncated relative of the vaccinia virus (VACV) E3 double‐stranded RNA (dsRNA) binding protein that inhibits protein kinase R (PKR), can also antagonize the type I IFN‐induced antiviral state in a highly species‐specific manner. In cells pre‐treated with type I IFN prior to infection, MYXV exploits M029 to overcome the induced antiviral state completely in rabbit cells, partially in human cells, but not at all in mouse cells. However, in cells pre‐infected with MYXV, IFN‐induced signaling is fully inhibited even in the absence of M029 in cells from all three species, suggesting that other MYXV protein(s) apart from M029 block IFN signaling in a speciesindependent manner. We also show that the antiviral state induced in rabbit, human or mouse cells by type I IFN can inhibit M029‐knockout MYXV even when PKR is genetically knocked‐out, suggesting that M029 targets other host proteins for this antiviral state inhibition. Thus, the MYXV dsRNA binding protein M029 not only antagonizes PKR from multiple species but also blocks the type I IFN antiviral state independently of PKR in a highly species‐specific fashion.

Date Created
2017-02-02
Agent