Human Epidermal Growth Factor Receptor 2 (HER-2/neu) is a breast tumor antigen (Ag) commonly overexpressed in 30% of breast cancer cases. Both HER-2/neu-targeted DNA-based and transgene modified dendritic cell (DC)-based vaccines are potent elements in eliciting HER-2/neu specific antitumor immune responses; however, there has been no side-by-side comparison of these two different immunization methods. We utilized an in vivo murine tumor model expressing the rat neu Ag to compare the immunization efficacy between DC transduced with replication-deficient adenovirus containing neu (AdVneu), to form DCneu, and plasmid DNA (pcDNA) vaccine. DCneu displayed an upregulation of immunologically important molecules and inflammatory cytokines expression such as IL-6 that partially mediated conversion of the regulatory T (Tr) cell suppression. Wildtype FVB/N mice immunized with DCneu induced stronger HER-2/neu-specific humoral and cellular immune responses compared to plasmid DNA immunized mice. Furthermore, mice immunized with DCneu remained completely protected from tumor challenge compared to partial or no protection observed in DNA immunized mice in two tumor animal models. In FVBneuN transgenic mice, which develop spontaneous breast tumors at 4-8 months of age, DCneu significantly delayed tumor onset when immunization conducted in mice at a younger age. Taken together, we demonstrated that a HER-2/neu-gene modified DC vaccine is more potent than a plasmid DNA vaccine in inducing neu specific immune responses resulting in greater protective and preventative effects in the tumor models examined. <p>In another study, we examined the use of a DC-based cancer vaccine involving the phagocytosis of apoptotic tumor cells expressing heat shock protein 70 (HSP70). The dual role of HSP70, as an antigenic peptide chaperone and danger signal, makes it especially important in DC-based vaccination. In this study, we investigated the impacts of apoptotic transgenic MCA/HSP tumor cells expressing HSP70 on DC maturation, T cell stimulation and overall vaccine efficacy. We found that DC with phagocytosis of MCA/HSP in the early phase of apoptosis expressed more peptide-major histocompatibility class (pMHC) I complexes, stimulated stronger cytotoxic T lymphocytes (CTL) responses and induced greater immune protection against MCA tumor cell challenge, compared to mice immunized with DC that phagocytosed MCA/HSP cells in the late phase of apoptosis. Taken together, our data demonstrated that HSP70 expression on apoptotic tumor cells stimulated DC maturation and DC with phagocytosis of apoptotic tumor cells expressing HSP70 in early phase of apoptosis more efficiently induced tumor-specific CTL responses and immunity than DC with phagocytosis of apoptotic tumor cells in late phase of apoptosis. <p>Overall, we have examined variations in designing DC-based cancer vaccines in two completely different model systems. Taken together, our results may have an important impact in designing DC-based antitumor vaccines.

Although wild birds are natural hosts of avian influenza viruses (AIVs), these viruses can be highly contagious to poultry and a zoonotic threat to humans. The propensity of AIV for genetic variation through genetic shift and drift allows virus to evade vaccine mediated humoral immunity. An alternative approach to current vaccine development is induction of CD8+ T cells which responds to more conserved epitopes than humoral immunity and targets a broader spectrum of viruses. Since the memory CD8+ T lymphocyte responses in chickens to individual AIV proteins have not been defined, the modulation of responses of the memory CD8+ T lymphocytes to H5N9 AIV hemagglutinin (HA) and nucleocapsid (NP) proteins over a time course were evaluated. CD8+ T lymphocyte responses induced by intramuscular inoculation of chickens with AIV HA and NP expressing cDNA plasmids or a non-replicating human adenovirus vector were identified through ex vivo stimulation with virus infected, major histocompatibility complex (MHC) matched antigen presenting cells (APCs). The IFN? production by activated lymphocytes was evaluated by macrophage production of nitric oxide and ELISA. MHC-I restricted memory T lymphocyte responses were determined at 10 days and 3, 5, 7 and 9 weeks post-inoculation (p.i). The use of non-professional APCs and APC driven proliferation of cells with CD8+ phenotype correlated with the activation of CD8+ T lymphocytes. The responses specific to nucleocapsid protein (NP) were consistently greater than those to the hemagglutinin (HA) at 5 weeks when the CD8+ T cell responses were maximum. By 8 to 9 weeks p.i., responses to either protein were undetectable. The T lymphocytes also responded to stimulation with a heterologous H7N2 AIV infected APCs. Administration of booster dose induced secondary effector cell mediated immune responses which had greater magnitudes than primary effector responses at 10 days p.i. Flow cytometric analysis (FACS) of the T lymphocytes demonstrated that memory CD8+ T lymphocytes of chickens can be distinguished from naive lymphocytes by their higher expression of CD44 and CD45 surface antigens. CD45 expression of memory lymphocytes further increases upon ex vivo stimulation with APCs expressing AIV. This is the first characterization of avian memory responses following both primary and secondary expression of any individual viral protein.

Proopiomelanocortin (POMC) is a 241 amino acids precursor protein, which encodes various neuropeptides including corticotropin (ACTH), a-melanocyte-stimulating hormone (a-MSH), and b-endorphin (b-EP). POMC plays an important role in stress response, metabolism, energy homeostasis and anti-inflammation. Recent studies demonstrated that systemic POMC gene delivery potently suppresses the tumor growth and metastasis of B16-F10 melanoma in vitro and in vivo via inhibition of NF-£eB/COX2 pathway. However, systemic POMC expression also led to elevated urine excretion and water intake in mice. This was attributed to enhanced steroidgenesis as evidence by elevated plasma corticosteroids levels in animals and increased cortisol production in adrenal H295R cells after POMC gene delivery. Since corticosteroids are also potent anti-inflammatory agents, it remains unclear whether the ACTH-mediated cortisol synthesis also contributed to the POMC-induced tumor suppression. To address this issue, we generated a series of adenovirus vectors encoding POMC genes with mutation or deletion in ACTH domain including ACTH (K15A/R17A). Unlike the wild type POMC, gene delivery of ACTH (K15A/R17A) resulted in significantly lower cortisol production, CYP11B1 mRNA level, and glucocorticoid responsive element (GRE)-driven luciferase activities in H295R cells. ACTH (K15A/R17A) gene delivery did not affect the urination and water intake in mice. Above all, ACTH (K15A/R17A) gene delivery remained capable of inhibiting the colonies formation and invasiveness of B16-F10 melanoma cells. In summary, steroidgenesis is not essential to POMC-mediated melanoma suppression. In addition, ACTH (K15A/R17A) gene delivery may provide a better alternative for melanoma control.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

L’adénovirus a été étudié dans l’optique de développer de nouveaux traitements pour différentes maladies. Les vecteurs adénoviraux (AdV) sont des outils intéressants du fait qu’ils peuvent être produits en grandes quantités (1X1012 particules par millilitre) et de par leur capacité à infecter des cellules quiescentes ou en division rapide. Les AdVs ont subi bon nombre de modifications pour leur permettre de traiter des cellules tumorales ou pour transporter des séquences génétiques exogènes essentielles pour le traitement de maladies monogéniques. Toutefois, les faibles niveaux d’expression du récepteur primaire de l’adénovirus, le CAR (récepteur à l’adénovirus et au virus coxsackie), réduit grandement l’efficacité de transduction dans plusieurs tumeurs. De plus, certains tissus normaux comme les muscles n’expriment que très peu de CAR, rendant l’utilisation des AdVs moins significative. Pour pallier à cette limitation, plusieurs modifications ont été générées sur les capsides virales. L’objectif de ces modifications était d’augmenter l’affinité des AdVs pour des récepteurs cellulaires spécifiques surexprimés dans les tumeurs et qui seraient exempts dans les tissus sains avoisinant. On peut mentionner dans les approches étudiées: l’utilisation de ligands bispécifiques, l’incorporation de peptides dans différentes régions de la fibre ou la substitution par une fibre de sérotypes différents. Notre hypothèse était que les domaines d’interaction complémentaire (K-Coil et ECoil) permettraient aux ligands de s’associer aux particules virales et d’altérer le tropisme de l’AdV. Pour ce faire, nous avons inclus un domaine d’interaction synthétique, le K-Coil,dans différentes régions de la fibre virale en plus de générer des mutations spécifiques pour abolir le tropisme naturel. Pour permettre la liaison avec les récepteurs d’intérêt dont l’EGF-R, l’IGF-IR et le CEA6, nous avons fusionné le domaine d’interaction complémentaire, le E-Coil, soit dans les ligands des récepteurs ciblés dont l’EGF et l’IGF-I, soit sur un anticorps à un seul domaine reconnaissant la protéine membranaire CEA6, l’AFAI. Suite à la construction des différents ligands de même que des différentes fibres virales modifiées, nous avons determiné tout d’abord que les différents ligands de même que les virus modifiés pouvaient être produits et que les différentes composantes pouvaient interagir ensemble. Les productions virales ont été optimisées par l’utilisation d’un nouveau protocole utilisant l’iodixanol. Ensuite, nous avons démontré que l’association des ligands avec le virus arborant une fibre modifiée pouvait entraîner une augmentation de transduction de 2 à 21 fois dans différentes lignées cellulaires. À cause de la difficulté des adénovirus à infecter les fibres musculaires occasionnée par l’absence du CAR, nous avons cherché à savoir si le changement de tropisme pourrait accroître l’infectivité des AdVs. Nous avons démontré que l’association avec le ligand bispécifique IGF-E5 permettait d’accroître la transduction autant dans les myoblastes que dans les myotubes de souris. Nous avons finalement réussi à démontrer que notre système pouvait induire une augmentation de 1,6 fois de la transduction suite à l’infection des muscles de souriceaux MDX. Ces résultats nous amènent à la conclusion que le système est fonctionnel et qu’il pourrait être évalué dans des AdVs encodant pour différents gènes thérapeutiques. / Adenoviruses have been studied as a way to develop new treatments for different diseases. Adenoviral vectors (AdV) are considered interesting tools for this propose, because they can be produced at high titers (1X1012 particles per millilitre) in laboratory and they have the capacity to infect non-dividing and dividing cells. AdV have been often modified in order to obtain the ability to kill tumour cells or to deliver exogenous genetic sequences essential to treat monogenic disease. However, weak expression of the primary adenovirus receptor, the CAR (Coxsackie and adenovirus receptor) reduces greatly the transduction efficiency of AdV for the tumour cells. Moreover, some normal tissues express low amount of CAR, like the skeletal muscle, reducing the appeal of using AdV as a gene delivery vehicle for this tissue. To address this problematic, many modifications were done on the adenoviral capsid. The goal of these modifications were to generate an AdV able to target specific cellular receptors that were expressed in tumour cells but not in normal cells. Several approaches were done to modify the tropism of AdV, such as incubation with a bispecific ligands, incorporation of peptides within the adenoviral fiber structure or substitution of the viral fiber with a different serotype fiber. The hypothesis of my project was to determine if an interaction domain fused within a ligand could bind the complementary domain incorporated on a virus and change the tropism of the AdV. The first step was to include a synthetic interaction domain, the K-Coil, within specific region of the adenoviral fiber, as well as inserting two point mutations to abolish the natural tropism. To target the EGF-R, IGF-IR and the CEA6, we fused the complementary interaction domain, the E-Coil, to the respective ligand known as the EGF and the IGF-I or to a single domain antibody (known as AFAI) that bind specifically to CEA6. The specific interaction between the E-Coil and K-Coil was used to associate the ligand with the fiber in order to retarget the AdV toward the selected receptor. We showed that the different ligands as well as the modified fibers could be produced and that both E-Coil and K-Coil expressing partners could interact together. We optimized the viral production by using an iodixanol purification protocol. More importantly, we clearly demonstrated that the ligand association with the fiber could increase the transduction efficiency between 2 to 21 fold against various tumour cells. The difficulty of adenovirus to infect muscle cells because of the lack of CAR expression brought us to evaluate the potential of our retargeted AdV to increase the transduction for the tissue. We showed that the use of IGF-E5 could increase the transduction efficiency in myoblasts as wells as in myotubes. We finally demonstrated that our retargeting system could increase the transduction efficiency for skeletal muscle by 1,6 fold in new born MDX mice. In conclusion, our results show that the retargeting system is indeed functional. This system could be assessed using vectors that express therapeutic genes.

All challenges associated with influenza A viruses including antigenic variation in hemagglutinin (HA) and neuraminidase (NA), the evolving drug resistance and the drawbacks of current vaccines hinder our ability to control this constant threat. Furthermore, gene reassortment as well as the direct transmission of highly pathogenic avian viruses to humans can result in an occasional emergence of novel influenza strains with devastating pandemic potential. Therefore, it is crucial to investigate alternative approaches to better control these viruses and to develop new prophylactic and treatment options. Targeting highly conserved epitopes or antigens among the different subtypes of influenza A virus could offer protection against broad range of influenza viruses, including emerging strains. In my research, I have investigated the potential of broadly neutralizing antibodies against HA and conducted mechanistic study of a prototype vaccine based on the highly conserved nucleoprotein (NP). We recently found that the 14 amino acids of the amino-terminus of the fusion peptide of influenza HA2 subunit is the only universally conserved sequence in all HA subtypes of influenza A and the two lineages of influenza B viruses. Here, I show that universal antibodies targeting this linear sequence in the viral HA (Uni-1 antibodies) can cross-neutralize multiple subtypes of influenza A virus by inhibiting the pH-dependant fusion of viral and cellular membranes. It is noted that the influenza NP is a highly conserved antigen and has the potential to induce heterosubtypic immunity against divergent subtypes of influenza A virus. However, NP-based vaccination only affords weak protective immunity compared to HA. This is mostly due to the non-sterilizing immunity induced by NP. Using CD40 ligand (CD40L), a key regulator of the immune system, as both a targeting ligand and a molecular adjuvant, I show that single immunization with recombinant adenovirus carrying a fused gene encoding the secreted NP-CD40L fusion protein provided robust and long-lasting protection against influenza in normal mice. It enhanced both B-cell and T-cell responses and augmented the role of both NP-specific antibodies and CTLs in protection. Importantly, it afforded effective protection in CD40L and CD4 deficient mice, confirming that the induced protection is CD40L-mediated and CD4+ T cell-independent. The rapid evolution of the influenza A viruses necessitates the development of new alternatives to contain this medically important pathogen. The results of these studies could significantly contribute to future vaccine development and avert the necessity of yearly vaccine updates.

Regulation of adenoviral gene expression is a complex process directed by viral proteins controlling a multitude of different activities at distinct phases of the virus life cycle. This thesis discusses adenoviral regulation of transcription and splicing by two proteins expressed at the late phase: L4-22K and L4-33K. These are closely related with a common N-terminus but unique C-terminal domains. The L4-33K protein is an alternative RNA splicing factor inducing L1-IIIa mRNA splicing, while L4-22K is stimulating transcription from the major late promoter (MLP). The L4-33K protein contains a tiny RS-repeat in its unique C-terminal end that is essential for the splicing enhancer function of the protein. Here we demonstrate that the tiny RS-repeat is required for localization of the protein to the nucleus and viral replication centers. Further, we describe an auto-regulatory loop where L4-33K enhances splicing of its own intron. The preliminary characterization of the responsive RNA-element suggests that it differs from the previously defined L4-33K-responsive element activating L1-IIIa mRNA splicing. L4-22K lacks the ability to enhance L1-IIIa splicing in vivo, and here we show that the protein is defective in L1-IIIa or other late pre-mRNA splicing reactions in vitro. Interestingly, we found a novel function for the L4-22K and L4-33K proteins as regulators of E1A alternative splicing. Both proteins selectively upregulated E1A-10S mRNA accumulation in transfection experiments, by a mechanism independent of the tiny RS-repeat. Although L4-22K is reported to be an MLP transcriptional enhancer protein, here we show that L4-22K also functions as a repressor of MLP transcription. This novel activity depends on the integrity of the major late first leader 5’ splice site. The model suggests that at low concentrations L4-22K activates MLP transcription while at high concentrations L4-22K represses transcription. So far, characterizations of the L4-22K and L4-33K proteins have been limited to human adenoviruses 2 or 5 (HAdV-2/5). We expanded our experiments to include HAdV-3, HAdV-4, HAdV-9, HAdV-11 and HAdV-41. The results demonstrated that the transcription- or splicing-enhancing properties of L4-22K and L4-33K, respectively, are evolutionarily conserved and non-overlapping. Thus, the sequence-based conservation is mirrored by the functions, as expected for functionally important proteins.

The coxsackie-adenovirus receptor (CAR) is a viral receptor for Group B coxsackieviruses (CVB). Physiologically, CAR is a cellular adhesion protein. I report that upregulation of cardiac CAR in the young adult mouse (CAR+/MtTA+ ) caused a cardiomyopathy that was characterized by inflammation and hypertrophy. In the hearts of CAR+/MtTA+ mice c-Jun N terminal kinase (JNK) was specifically activated. JNK activation is known to promote hypertrophy of cardiomyocytes, and disrupt proteins at the intercalated disc. CVB3-infected CAR+/MtTA+ mice did not exhibit increased cardiac viral load or myocarditis severity, but did demonstrate a greater cardiac interferon-γ (IFN-γ) response when compared to littermate controls. CAR-induced expression of this antiviral cytokine may have prevented the increase in myocarditis susceptibility. Further investigation into the activation of protein kinase signaling, and antiviral signaling will provide better understanding of how CAR participates in the pathogenesis of both viral and non-viral heart diseases.

The coxsackie-adenovirus receptor (CAR) is a viral receptor for Group B coxsackieviruses (CVB). Physiologically, CAR is a cellular adhesion protein. I report that upregulation of cardiac CAR in the young adult mouse (CAR+/MtTA+ ) caused a cardiomyopathy that was characterized by inflammation and hypertrophy. In the hearts of CAR+/MtTA+ mice c-Jun N terminal kinase (JNK) was specifically activated. JNK activation is known to promote hypertrophy of cardiomyocytes, and disrupt proteins at the intercalated disc. CVB3-infected CAR+/MtTA+ mice did not exhibit increased cardiac viral load or myocarditis severity, but did demonstrate a greater cardiac interferon-γ (IFN-γ) response when compared to littermate controls. CAR-induced expression of this antiviral cytokine may have prevented the increase in myocarditis susceptibility. Further investigation into the activation of protein kinase signaling, and antiviral signaling will provide better understanding of how CAR participates in the pathogenesis of both viral and non-viral heart diseases.

Thesis (M.S.) -- University of Texas Southwestern Medical Center at Dallas, 2003. / Vita. Bibliography: 45-48.