Virology Commons^™

Evolution Of Overlapping Reading Frames In Virus Genomes, Laura Muñoz Baena

Electronic Thesis and Dissertation Repository

Viruses are formidable pathogens that represent the majority of biological entities in our planet, and their genomes are a source of interesting enigmas. One feature in which virus genomes are usually rich, is the presence of overlapping reading frames (OvRFs) — portions of the genome where the same nucleotide sequence encodes more than one protein. OvRFs are hypothesized to be used by viruses to encode proteins more compactly and to regulate transcription. In addition, OvRFs might be a source of gene novelty, facilitating the creation of new open reading frames (ORF) within the transcriptional context of existing ones.

To characterize …

Exploration Of The Immune Landscape Of Ebv-Associated Gastric Cancers, Mikhail Salnikov

Electronic Thesis and Dissertation Repository

Epstein–Barr virus (EBV) is a gammaherpesvirus associated with 9% of all gastric cancers (GCs). EBV-associated GCs (EBVaGCs) are pathologically and clinically distinct entities from EBV-negative GCs (EBVnGCs), with EBVaGCs exhibiting differential molecular pathology and patient prognosis. The purpose of this thesis is to investigate the tumor microenvironment (TME) of EBVaGCs, which has not been explored in-depth. We hypothesize that EBVaGCs and EBVnGCs are also distinct in terms of the molecular immune landscape. We employed over 400 stomach adenocarcinoma (STAD) samples from The Cancer Genome Atlas (TCGA), as well as a single cell dataset, for the construction of a web suite …

Molecular Characterization Of The Antiviral Properties Of The Small Herc Family Of Proteins, Ermela Paparisto

Electronic Thesis and Dissertation Repository

Although viruses are obligate intracellular parasites, they have their own evolutionary trajectory, their genomes are in a constant battle to overcome the defenses of the host. This thesis investigates the role of the small HERC family of proteins in the battle against two deadly viruses: Human Immunodeficiency Virus -1 (HIV) and Zaire ebolavirus (EBOV). Although their discovery occurred decades ago, little knowledge is available about the small HERC family, their functions, and modes of interactions with other cellular proteins. In the first chapter, the structural evolution of the small HERC family and related functional changes that have occurred over time …

Using A One Health Approach For The Assessment Of Rabies Control In Rural Victoria Falls, Zimbabwe, Ryan Lapenna

Electronic Thesis and Dissertation Repository

Rabies, a viral zoonotic disease, is widespread in Zimbabwe, with human fatalities reported annually in the country. To supplement the Government’s effort on rabies control, the Victoria Falls Wildlife Trust and Veterinarians for Animal Welfare Zimbabwe have joined forces to carry out dog rabies vaccinations in rural communities adjacent to the major tourist attraction of The Victoria Falls. A One Health approach was used to 1) determine the level of protective rabies antibodies among a sample of rural dogs and 2) collect information and describe the knowledge, attitudes, and practices related to rabies among dog owners. In 2020, blood was …

Developing A Nasal Organotypic Model To Investigate The Effects Of The Nasal Microbiome On Susceptibility To Pathogens, Victor H.K. Lam Mr.

Undergraduate Student Research Internships Conference

The microbiota is essential to the functioning of the immune system. The nasal milieu secretes immune molecules that can be influenced by diverse bacteria. Hence commensals that enhance anti-viral responses may confer resistance to respiratory viral infection.

Our collaborators have identified 7 microbial state types (CST) defined by indicator species in the nose and recently, through analyses of nasal immune molecules, we have categorized the nasal immune profile types into 8 groups (IPT). Although the IPTs correlated with certain CSTs, the influence of the nasal microbiome on susceptibility to respiratory pathogens is still unknown.

Defining this complex relationship requires a …

Regulation Of Mhc Ii Trafficking And Expression By Host And Viral Factors, Alex Lac

Electronic Thesis and Dissertation Repository

Antigen presentation by major histocompatibility complex class II (MHC II) to the adaptive immune system is crucial for mounting sterilizing immune responses. This central role has made antigen presentation a target for antagonism by many pathogens. Notably, infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) decrease MHC II expression in several immune cells. The mechanisms responsible for this suppression are unknown but involves either redirecting MHC II molecules away from the cell surface or inhibiting MHC II expression. To understand how pathogens manipulate intracellular MHC II trafficking, we first investigated the role of the Golgi trafficking regulator, ERC1, in …

Hiv-1 Drug Resistance To Integrase Strand Transfer Inhibitors In Hiv-1 Non-B Subtypes, Emmanuel Ndashimye

Electronic Thesis and Dissertation Repository

Human immunodeficiency syndrome (HIV-1) has infected over 75 million people and over 35 million have succumbed to virus related illnesses. Despite access to a variety of antiretroviral therapy (ART) options, ART programs have been disproportionally spread in the world with low-and middle-income countries (LMICs) facing challenges to access the most potent ART options. With less potent ART remaining in use in LMICs, HIV-1 drug resistance (HIVDR) presents a growing challenge in LMICs. Since approval of the first-generation integrase strand transfer inhibitor (INSTIs), Raltegravir (RAL) in 2007, INSTIs remain the best choice as a backbone of ART. Access to second generation …

A Workflow To Analyze Ethcd Mass Spectrometry Data For Studying Hiv Gp120 Glycosylation, Yingxue Sun

Electronic Thesis and Dissertation Repository

The great heterogeneity of HIV populations and richness of surface glycan clouds makes it difficult to locate a conserved and exposed protein epitope as an effective vaccine target. However, more than 80% new infections result from single transmitted founder (T/F) viruses. We set out to design a workflow to study the traits of T/Fs that allow for their superior infectivity, specifically, the glycosylation patterns of gp120, a subunit of HIV envelope protein responsible for binding to host cell receptors. Our main research methods include Western blot and mass spectrometry. Our current understanding of the mass spectrometry data indicates that our …

Characterization And Discovery Of Short Linear Motifs Mediating Protein Nuclear Import, Tanner M. Tessier

Electronic Thesis and Dissertation Repository

Protein-protein interactions (PPI) mediated through short linear motifs (SLiMs) are ubiquitous throughout the human proteome and are involved in many essential cellular processes. One such type of SLiM is the classical nuclear localization sequence (cNLS), which facilitates nuclear import by binding importin-α (Imp-α). This pathway is indispensable to many cellular processes and is extensively used by viral proteins that function within the nucleus of infected cells. Based on this, I demonstrated that the classical nuclear import pathway inhibitor, ivermectin, can inhibit replication of human adenovirus. Treatment with ivermectin blocks nuclear localization of the E1A protein, an essential viral nuclear protein …

Molecular Identification And Characterization Of Viral Pathogens Infecting Sweet Cherry, Aaron J. Simkovich

Electronic Thesis and Dissertation Repository

Stone fruits are a valuable crop grown worldwide, however pathogens such as viruses threaten fruit production by reducing tree health and fruit yield. In an orchard within the Niagara region of Ontario, symptoms typical of viral infection such as chlorosis and leaf deformation were seen on sweet cherry (Prunus avium L.) trees. Next generation sequencing was performed on symptomatic and asymptomatic leaves and four viruses were identified. On the tree displaying the most severe symptoms, Prune dwarf virus (PDV), was the only virus detected. A survey conducted during this work showed 42% of cherry trees on a single …

Designing A Novel Hiv-1 Candidate Vaccine, Rahul Pawa

Electronic Thesis and Dissertation Repository

Currently no vaccine has been developed that can prevent the spread of HIV-1. During sexual transmission, a single viral variant called the Transmitted/Founder (T/F) purportedly with unique physical properties, establishes infection in 70-80% of individuals. Unlike previous studies that have tried to identify T/F viruses based on their structure glycan composition and amino acid sequence, we have analyzed the RNA sequences of HIV-1 to help identify T/F variants. Using a combination of both in silico data analysis and in vitro assays, we have identified that T/F viruses have higher numbers of immunostimulatory motifs than HIV virions that fail to infect. …

Utilizing Fiv (Feline Immunodeficiency Virus) To Develop A Novel Animal Model To Study Hiv (Human Immunodeficiency Virus), Ankita Suryakant Kambli

Electronic Thesis and Dissertation Repository

This project sought to perform the in vitro work needed to accomplish the long-term vision of harnessing the similarities between HIV (Human Immunodeficiency Virus) and FIV (Feline Immunodeficiency Virus) to develop an animal model whereby cats can be used to study HIV pathogenesis and therapeutics. We transfected CRFK (Crandell Rees Feline Kidney) fibroblasts with plasmids that could express human or feline CD4, CCR5, or both, and determined receptor surface expression through flow cytometry. We discovered that HIV envelope expressed on 293T can fuse with huCD4/huCCR5 on CRFK. These cat cell lines were also capable of supporting HIV infection. Additionally, we …

Encountering Lectins In The Recipient Mucosa: Implications Of N-Linked Glycosylation On Hiv-1 Transmission, Adam Meadows

Electronic Thesis and Dissertation Repository

Although several studies have determined key differences in envelope motifs between TF and chronic HIV-1, it is still not known what the overall glycosylation profile is that is selected for in a transmission event, as well as what contributes to this selection. Using a bottom-up approach of modifying specific viruses, determining their transmission fitness in an ex vivo tissue explant assay, and determining their glycan content, we have laid the basis for determining the overall glycan structure which is selected for in TF HIV-1. Preliminarily, we have shown that C-type lectins represent a stringent barrier to transmission and have several …

Determining The Relative Transmission Fitness Of Hiv-1 Subtypes A, B, C, And D, Spencer Yeung

Electronic Thesis and Dissertation Repository

There is in vivo evidence that suggests the genetic diversity of HIV-1 subtypes influence heterosexual transmission efficiency. To recapitulate sexual transmission in vitro, blocks of genital tissue were exposed to mixtures of genetically different subtype viruses. Migrating immune cells were collected and co-cultured with a CD4+ T-cell line permissive to HIV infection (PM1) to measure dendritic cell virus transfer; HIV-exposed tissues were cultured separately. Next generation sequencing (NGS) of HIV-1 DNA was used to quantify relative infection rates of the various challenge viruses, and to assess fitness differences in infection of the tissue vs. migratory/T cell co-cultures. Our results …

Endogenous, Controlled Expression Of Anti-Hiv-1 Broadly Neutralizing Antibody, Darshit Patel

Electronic Thesis and Dissertation Repository

Recently, researchers have identified a number of anti-HIV broadly neutralizing antibodies (bNAbs), such as VRC01 and N6, capable of targeting a broad range of HIV-1 strains. Passive immunization using these patient-derived bNAbs could provide temporary protection but are limited by the short antibody half-life. While current gene transfer technology allows sustained bNAb expression, it lacks the ability to control bNAb production in vivo resulting in possible autoimmunity. To address this issue of achieving controlled bNAb expression in vivo, we hypothesize that bNAb expression from transduced Flu-specific B cells can be activated and modulated by subsequent Flu immunizations in the …

Role Of Gp120 Glycosylation In Sexual Transmission Of Hiv, Yingxue Sun, Adam Meadows, Najwa Zebian, Eric Arts, Carole Creuzenet

Western Research Forum

Background:

In chronic HIV patients, the viral populations are genetically diverse due to mutations introduced by the viral reverse transcriptase during HIV replication. However, more than 80% new infections result from single transmission founder (TF) viruses; therefore, targeting the TFs is key to control AIDS worldwide.

Gp120 is a glycosylated envelope protein required for HIV infection, propagation, and transmission. Glycans on gp120 influence HIV infectivity through their interactions with lectins, the carbohydrate-binding immune proteins in the host mucosa. To transmit sexually, viruses must overcome the lectin traps to access more target T cells.

Hypothesis:

TF viruses are less likely to …

Hiv-1 Group M Subtype Fitness, Disease Progression, And Entry Efficiency, Colin M. Venner

Electronic Thesis and Dissertation Repository

Human immunodeficiency virus type 1 (HIV-1) emerged in the human population shortly after the turn of the 19th century. Distribution of HIV-1 across the globe over the past 30–35 years can be traced to founder events with primordial HIV strains from sub-Saharan Africa. Even considering the burden of HIV in Africa, our knowledge of HIV-1 disease is still largely limited to subtype B HIV-1, a strain responsible for 3 million infections in North America and Europe as compared to the 33 million that are infected with HIV-1 subtypes A, C, D, and circulating and unique recombinant forms.

This dissertation analyzes …

Novel Insights Into The Genomic Integration Site Landscape Of Hiv-1 And Other Retrovirus Genera, Hinissan P. Kohio

Electronic Thesis and Dissertation Repository

An important event during infection by retroviruses such as human immunodeficiency virus type 1 (HIV-1) is the permanent integration of the viral genome into the host genome. This event leads to life-long infection and is accompanied by a period of quiescence/latency ranging from a few years to >10 years where HIV-1 expression is barely detectable or undetectable. Despite the use of combination antiretroviral therapy (cART) which controls HIV-1 infection, quiescent/latent virus presents a major obstacle towards a functional cure. Integration site location in the genome is thought to contribute to latent infections and has the potential to confound anti-latency treatments, …

Determining The Molecular Mechanisms Of Pacs-1-Mediated Protein Sorting, Brennan S. Dirk

Electronic Thesis and Dissertation Repository

Membrane trafficking events are required to direct proteins to their precise subcellular locations. The cellular Phosphofurin Acidic Cluster Sorting protein – 1 (PACS-1) has emerged as a protein of interest in controlling the localization of a multitude of cellular and viral proteins. Specifically, PACS-1 is hijacked by type-1 Human Immunodeficiency Virus (HIV-1) to contribute to immune evasion in addition to regulating neuroendocrine hormone storage and release. To accomplish this, PACS-1 connects the cytoplasmic tail of cellular receptors to the heterotetrameric adaptor proteins (APs) to form a functional trafficking unit. Throughout this dissertation, I explored the role of PACS-1 and AP-1 …

Interferon-Induced Herc5 Is A Novel And Potent Inhibitor Of Ebola Virus-Like Particle Production, Nina Hunt

Electronic Thesis and Dissertation Repository

Ebola’s severe pathogenesis can be attributed to its suppression of the Type I interferon (IFN) response, suggesting this pathway plays a role in restricting viral replication. One IFN-induced protein, HERC5, warrants further investigation as it inhibits the replication of evolutionarily diverse viruses. We showed that HERC5 drastically reduces the expression of structural protein VP40 at the protein and mRNA level. Mutagenesis of HERC5 demonstrated that the RCC-1-like domain is necessary and sufficient for restriction. This domain is also responsible for HERC5’s interaction with ZAP, a protein required for VP40 mRNA degradation. Finally, we showed that Ebola GP antagonizes HERC5 activity. …

The Role Of The Hiv-1 Accessory Proteins Nef And Vpu In Subverting Host Cellular Immunity, Emily N. Pawlak

Electronic Thesis and Dissertation Repository

The HIV-1 accessory proteins Nef and Vpu have no known enzymatic activity, yet these viral proteins are critical for HIV-1 viral spread and pathogenicity. To mediate this, these viral proteins bind to and hijack host cellular proteins, including proteins implicated in the membrane trafficking machinery. Key to the effects of these proteins is their ability to alter the subcellular localization of a plethora of cell surface receptors, including the key immune cell receptorsCD28 and MHC-I.However,the mechanism utilized by Nef and Vpu to modulate these proteins is not fully understood. Herein, we demonstrated that Nef and Vpu mediate a decrease in …

Understanding The Impact Of Hiv-1 Genetic Diversity On The Function Of Nef And Its Role In Serinc5 Antagonism, Aaron Leslie Johnson

Electronic Thesis and Dissertation Repository

HIV-1 Nef is a key pathogenic protein, allowing HIV-1 to evade the host immune system by downregulating MHC-I and CD4. Furthermore, it was recently discovered that Nef counteracts the host factor SERINC5 to increase HIV-1 infectivity, but the mechanistic details of the Nef:SERINC5 interaction still need to be explored. Throughout this dissertation, I will explore the hypothesis that the genetic diversity that defines HIV-1 has a pronounced effect on the HIV-1 protein Nef, altering its function between and within group M subtypes. To address this hypothesis I investigated how MHC-I and CD4 downregulation differ among all non-recombinant group M subtypes. …

Functional And Structural Mimicry Of A-Kinase Anchoring Proteins By Human Adenovirus E1a, Cason R. King

Electronic Thesis and Dissertation Repository

As an obligate intracellular parasite, human adenovirus (HAdV) must utilize host factors for survival and replication. Early during infection, its multifunctional E1A protein interacts with an impressive range of cellular target proteins to exert control over the cellular environment. Through these virus-host interactions, E1A massively reprograms both viral and cellular transcription to activate the other HAdV genes, downregulate the host’s immune response, and induce the cell cycle. Consequently, E1A converts the infected cell into a compliant state more amenable for HAdV replication, resulting from its numerous protein-protein interactions. I sought to examine E1A’s interaction with cellular protein kinase A (PKA), …

Characterizing The Interaction Between Human Adenovirus E1a And Sting, Jessica Hill

Electronic Thesis and Dissertation Repository

When challenged by viral DNA, the cytoplasmic DNA sensor cyclic GMP-AMP synthase (cGAS) signals through the adaptor protein stimulator of interferon genes (STING) to induce a primary type I IFN response. Studies from recent years have also revealed shared architecture between metabolism and innate immunity. Viruses have evolved to counteract these mechanisms. Human adenovirus (HAdV) early region 1A (E1A) protein antagonizes the cGAS-STING pathway to prevent an innate immune response by physically interacting with STING. I hypothesize that the interaction between E1A and STING is mediated through several motifs and involves ribosomal protein S6 kinase beta-1 (S6K1). Using a series …

The Effect Of Diet On Midgut And Resulting Changes In Infectiousness Of Acmnpv Baculovirus In Trichoplusia Ni, Elizabeth Chen

Electronic Thesis and Dissertation Repository

The cabbage looper, Trichoplusia ni, a global generalist lepidopteran pest, has developed resistance to many synthetic and biological insecticides, requiring effective and environmentally acceptable alternatives. One possibility is the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). This baculovirus is highly infectious for T. ni, with potential as a biocontrol agent, however, its effectiveness is strongly influenced by dietary context. In this study, microscopy and transcriptomics were used to examine how the efficacy of this virus was affected when T. ni larvae were raised on different diets. Larvae raised on potato host plants had lower chitinase and chitin deacetylase transcript levels …

Developing A Plant Virus-Based Expression System For The Expression Of Vaccines Against Porcine Reproductive And Respiratory Syndrome Virus, Hong Hanh Tran

Electronic Thesis and Dissertation Repository

Virus-based expression systems have been widely exploited for the production of recombinant proteins in plants during the last three decades. Advances in technology have boosted scale-up manufacturing of plant-made pharmaceuticals to high levels, via the complementation of transient expression and viral vectors. This combination allows proteins of interest to be produced in plants within a matter of days and thus, is well suited for the development of plant-made vaccines or therapeutics against emerging infectious diseases and potential bioterrorism agents. Several plant-based products are currently in varying stages of clinical development. To investigate the viability of virus-based expression systems for plant-made …

Characterizing The Interaction Between Human Adenovirus E1a And The Transcriptional Repressor Bs69, Ali Zhang

Electronic Thesis and Dissertation Repository

Protein products of the Early Region 1A (E1A) gene in human adenovirus 5 (HAdV-5) are the first viral proteins expressed upon adenovirus infection. E1A disrupts many cellular physiological events by binding to and regulating an impressive number of host factors. Of particular interest is BS69, a repressor of E1A transactivation. Due to the strong interaction observed between E1A and BS69, I hypothesize that these two proteins function together to disrupt gene expression within an infected cell.

Using in silico modelling and a series of yeast two-hybrid assays, I determined that residues 112-119 of HAdV-5 E1A is the minimal interacting region …

Investigating Adenovirus E1a As An Rna Polymerase Ii C-Terminal Domain Mimic And Its Role In Transcription Activation, Kristianne Jc Galpin

Electronic Thesis and Dissertation Repository

Viruses rely on host cell machinery, often mimicking cellular components, in order to circumvent host cell defenses and hijack cellular processes. DNA viruses, such as human Adenovirus (hAdV), rely on RNA Polymerase II (RNAPII) to transcribe viral genes. RNAPII has a C-terminal domain (CTD), made up of highly conserved heptad repeats of tyrosine-serine-proline-threonine-serine-proline-serine (YSPTSPS). Post-translational modifications of residues within the CTD, including phosphorylation, coordinates the transcription cycle. Several viruses, including Human Immunodeficiency Virus (HIV), Human Cytomegalovirus (hCMV), Epstein-Bar Virus (EBV) and Herpes Simplex Virus (HSV), modify the phosphorylation state of the RNAPII CTD by hijacking cellular cyclin dependent kinases (CDKs) …

Oncolytic Virus Therapy For The Treatment Of Metastatic Ovarian Cancer, Jessica Tong

Electronic Thesis and Dissertation Repository

The management of patients with epithelial ovarian cancer (EOC) faces two major challenges which standard treatments fail to effectively address: 1) Diffuse metastasis as a consequence of late stage diagnosis and 2) intra-tumoral heterogeneity, which fuels tumor evolution and drives the acquisition of chemotherapeutic resistance. In this thesis, we tested new therapeutic strategies using a 3-dimensional in vitro spheroid culture model that mimics key steps of epithelial ovarian cancer metastasis; and another model that mimics both temporal and cellular heterogeneity by establishing multiple cell lines from a single patient over the course of disease progression. Using these models, we investigated …

Characterizing The C-Terminal Region Of Human Adenovirus E1a: An Undiscovered Country, Michael J. Cohen

Electronic Thesis and Dissertation Repository

Human Adenovirus (HAdV) E1A is the first protein expressed during viral infection. The primary function of E1A is to reprogram the cell for viral replication, but it is additionally capable of transforming primary rodent cells in co-operation with other oncogenes such as HAdV E1B. Despite extensive study, little is known about the function and cellular targets of the C-terminal region of E1A. Importantly, this region is required for the transforming ability of E1A with E1B, but can also suppress transformation with Ras. Previous studies showed that interaction with the C-terminal Binding Protein (CtBP) plays a role in both functions described …