Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references (leaves 204-216). Also available via World Wide Web.

Bone marrow stromal antigen 2 (BST-2/tetherin) is a type II transmembrane protein that plays various roles, including protective and detrimental roles in the host. Cellular responses to BST-2 expression or the lack thereof, may be cell type and context-dependent and may vary with time. When protective, BST-2 functions as an antiviral factor, renowned for its ability to tether budding enveloped viruses to the membrane of infected cells. Tethering of budding virions prevents their release into the extracellular milieu limiting infection of naïve cells. The antiviral role of BST-2 has been predominantly studied using cultured cells. Insight into the role of BST-2 in inhibition of viral infection in vivo came from our study of the alphavirus Chikungunya virus (CHIKV) and the retrovirus mouse mammary tumor virus, (MMTV). BST-2 prevents the release of CHIKV and MMTV virions from infected cells and limits the replication of both viruses in mice. In the context of CHIKV infection, BST-2 protects the host in a tissue-type dependent manner. In lymphoid and most non-lymphoid tissues, expression of BST-2 limits CHIKV replication. In addition, BST-2 regulates CHIKV-induced inflammatory responses in mice, an indication that BST-2 may function to initiate and amplify innate immune responses. Host response to MMTV infection depends on the stage of the infection and disease sequela. Acute infection of immune cells with MMTV results in an initial increase in BST-2 expression followed by a sharp decline. In contrast, in MMTV-induced mammary tumors, BST-2 mRNA and protein are elevated, so is the viral load. This is an indication that the antiviral role of BST-2 is not operative once mammary tumors have developed. These data provided the initial evidence that BST-2 may promote breast cancer progression. Indeed, data from two mouse models of breast cancer show that expression of BST-2 is necessary for cell to cell and cell to extracellular matrix interactions. Thus, BST-2 expression in breast cancer cells enhances cancer cell adhesion, anchorage-independency, migration, and invasion, culminating in increased tumor mass, increased metastases, and reduced host survival. Structurally, BST-2 homodimerization is important for its cancer-promoting role as dimers of BST-2 regulate anchorage-independency, resistance to anoikis, and enhanced adhesion between cancer cells and components (proteins and cells) of the tumor microenvironment. How BST-2 is enriched in breast cancer cells was elusive until our in silico analyses of a large human breast cancer dataset that revealed the involvement of epigenetic regulation of BST-2 in breast tumors. In highly aggressive breast cancers, specific CpG sites in and at close proximity to the BST-2 promoter are hypomethylated. This is in sharp contrast to non-aggressive luminal cancers and normal breast epithelial cells. These data suggest that a progressive loss of methylation on the BST-2 gene may contribute to constitutive overexpression of BST-2 in tumors. Overall, these findings show that 1) BST-2 contributes to the emergence and progression of breast malignancies and may be used as a therapeutic target or as a biomarker for aggressive breast cancers; and, 2) BST-2 acts as a viral sensor to initiate antiviral inflammatory responses and could be exploited therapeutically to treat viral infections. We highlight the need for additional research on the antiviral and cancer-promoting roles of BST-2 to reconcile both functions for the purpose of therapeutics.

No description available.

The drug, N,N bis (ethylene)-P (1-adamantyl) phosphonic diamide inhibits focus formation of Rous Sarcoma Virus in tissue culture. Transformation of chick cells was inhibited when the drug was added to chick cells prior to infection. The drug did not inhibit the transformation of Normal Rat Kidney Cells infected with RSV, when the cells were grown at non-permissive temperatures and shifted to permissive temperatures upon addition of the drug. Nor did the drug revert cells transformed at permissive temperatures. These studies indicated that the inhibition of RSV is in the early stage of viral growth, possible penetration or uncoating.

A model for the study of the relationship of immunity to cancer is found in AKR mice which harbor Gross virus. This genetically transmitted virus is present in a latent form for months before it spontaneously induces leukemia. Many investigators have demonstrated near normal humoral responses, but abnormal cellular immunity in the preleukemic animal. With increasing age, pathology of the disease is expressed, reflecting diminished immunity. In this study, the ontogeny of humoral antibodies of AKR/J and SWR/J mice was assayed by microagglutination techniques in response to thymus-independent, thymus-dependent, and solubilized antigens. Simultaneous injections of thymusdependent and -independent antigens provided data suggesting an impaired humoral response in the AKR mouse.

O potencial oncogênico do papilomavírus humano (HPV) baseia-se na capacidade das oncoproteínas virais E6 e E7 alterarem o ciclo celular, levando à imortalização e malignidade das células. O importante papel das oncoproteínas na progressão tumoral e na interação com inúmeros alvos celulares tem relevância em estudos para o desenvolvimento de vacinas e terapias contra os cânceres associados ao HPV. Este estudo investigou a localização intracelular das oncoproteínas E6 e E7 de HPV16/18 e seus possíveis alvos celulares. Demonstrou a presença de E6 nuclear, citoplasmática e intramitocondrial, tanto em células naturalmente transformadas por HPV, como em células transfectadas com o oncogene E6 viral. E7 foi detectada no núcleo e citoplasma, porém nunca ocorreu E7 intramitocondrial. Confirmou a hipótese da presença intramitocondrial da oncoproteína viral E6 de HPV16/18 de alto risco. Dado inédito cuja relevância está relacionada com a aplicação clínica, no desenvolvimento de imunobiológicos e fármacos capazes de neutralizar a ação deste importante alvo terapêutico. / The oncogenic potential of HPV is based on the capacity of viral oncoproteins E6 and E7 to change cellular cycle leading to immortality and malignancy. The important role of oncoproteins in tumor progression and its interaction with numerous cellular targets have relevance in studies to the development of vaccines and therapies against HPV associated cancers. This study investigated intracellular localization of E6 and E7 HPV16/18 oncoproteins and its possible cellular targets. It showed the presence of E6 in the cellular nucleus, cytoplasm, and intramitochondrial in naturally HPV transformed cell, as well as in cells transfected with E6 viral oncogene. E7 was detected inside nucleus and cytoplasm, but E7 intramitochondrial did not occur. This study confirmed the hypothesis of the intramitochondrial presence of E6 viral oncoprotein from high risk HPV. This is an original data whose relevance is directly related to clinical application in the development of immunobiologicals and drugs, which are able to neutralize the action of this important therapeutic target.

The Jaagsiekte Sheep Retrovirus (JSRV), an exogenous type B/D-retrovirus with about 10-15 endogenous counterparts in all normal sheep genomes, causes Jaagsiekte (JS) or ovine pulmonary adenocarcinoma (OPA), a contagious lung cancer of sheep. This sheep lung cancer has been identified as the best natural out-bred model that can be used to study human epithelial tumours. The close similarity between the pathology of the sheep disease and Human Bronchiolo-alveolar carcinoma are highly suggestive that the human disease could have a similar aetiology and mechanism to the sheep disease. However, in the case of sheep at the time of the study there was a need for an assay that could be used to screen for infected sheep. The isolation, cloning and subsequent sequencing of the first full-length exogenous and endogenous forms of JSRV contributed greatly towards JSRV research. Until recently the diagnosis of OPA was based mostly on clinical presentation with confirmation by micro and macro examination of the affected lungs by expert pathologists. In the absence of a specific humoral response no serology-based tests were available to diagnose the disease early in live animals. Control and management of the disease was primarily by regular flock inspections and prompt culling of the suspected cases. The objective of this research project was therefore to assess and investigate the serological and molecular diagnosis of JSRV. In an attempt to develop a serology based assay three proteins were identified as candidate diagnostic antigens, the group specific antigen JSRV p26, the transmembrane and the orf-X proteins. Genes coding for all three proteins were isolated, cloned and expressed. The JSRV p26 was sufficiently purified and its potential as a diagnostic antigen was evaluated in both a Western blot and ELISA. Our studies confirmed that there were no circulating antibodies to the JSRV capsid protein. Evidence suggested that the immune response was localised to the lungs. Lung lavage samples were therefore collected from infected and normal sheep and analysed for the presence of JSRV p26 antibodies using an in-house JSp26 peroxidase conjugate in an antigen capture assay. This assay lacked sensitivity but the results indicated that there was a specific localised immune response to JSRV in the lungs of OPA affected sheep. This was confirmed with an in-house antigen capture assay that we developed. JS antigen was detected in the lung and nasal fluid of affected sheep, but not in equivalent samples from normal sheep. Three molecular assays were investigated for their sensitivity and specificity, the LTR-gag PCR, U3/LTR hemi-nested PCR and the PCR that covered the V1/V2 region. The U3/LTR hemi-nested assay was 2 logs more sensitive than the LTR-gag PCR. However, it detected the endogenous JSRV5.9A1 loci at higher concentrations. This was overcome by designing a more specific primer P3M for the first step of the U3/LTR hemi-nested PCR and the use of the AmpliTaq Gold DNA polymerase. This assay proved to be both sensitive and specific enough to screen for the infectious exogenous JSRV in peripheral blood samples from individual sheep. It is now possible to use this assay to selectively eradicate the disease from a flock through a selective culling programme. Furthermore, the assay could be made quantitative by the inclusion of concentration standards. / Thesis (M.Med.)-University of KwaZulu-Natal, 2005.

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves : 172-189). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 233-247). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 233-247). Also available on the Internet.