Thesis (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The solute carrier family 11 member 1 gene (SLC11A 1) is a divalent metal ion transporter with various pleiotropic effects on macrophage function. This gene that regulates iron, and is also regulated by cellular iron levels, has previously been linked to many infectious and autoimmune diseases. In this analysis, in vitro studies using the luciferase reporter system as well as case-control association studies were applied to investigate the significance of SLC11 A1 allelic variation in patients with diverse disease phenotypes. For in vitro studies, five different SLC11A 1 promoter constructs were generated, followed by transfection into U937 and THP-1 cells. The inserted fragments included two previously described alleles (alleles 2 and 3), two novel alleles identified in this study (alleles 8 and 9) and a C to T point mutation at nucleotide position -237 in the presence of allele 3. The most striking finding was the opposite effect observed for allele 3 in the presence of the -237C~ T polymorphism, similar to that of allele 2. Although the SLC11A 1 gene has previously been implicated in iron transport, we have demonstrated, for the first time, that the various alleles investigated cause differential expression of the gene upon iron loading. Association studies were performed by investigating diseases including oesophageal cancer (DC), inflammatory bowel disease (lBO) and hereditary haemochromatosis (HH) (or primary iron overload). Significant associations (P<O.05) were observed with allele 3 for all three conditions investigated only after stratification according to the presence of the -237C~ T polymorphism. Re-assessment of the promoter alleles according to expression profiles determined by the in vitro studies, showed statistically significant associations for allele 3 with DC and primary iron overload, compared with the respective population-matched control groups. Additionally, several novel variants were identified in exon 2 (112G~A, 148deIGACCAGCCC, 157insGACCAGCCCAG) and intron 1 (IVS1-28C~T), with variant IVS1-28C~T occurring at a significantly increased frequency in patients with DC compared with population-matched controls (P<O.05). Investigation of the SLC11A 1 gene in individuals presenting with iron overload in the absence of homozygosity for the HFE C282Y mutation, provided further support for the importance of sequence variation in the promoter region of the SLC11A 1 gene in modified risk of iron-related disorders. Genes related to iron homeostasis, including HFE, SLC11A3, HAMP and DCYTB, were investigated in individuals with similar criteria and potential disease-causing mutations were identified in 11% White and 45% Black South African patients. The possible significance of the SLC11A3 and DCYTB genes in iron overload in the Black South African population, and the possible involvement of the DCYTB gene in iron overload in general, are demonstrated for the first time. This study contributed to a better understanding of the function of the SLC11A 1 gene in relation to iron metabolism. The involvement of SLC11A 1 in a range of disease phenotypes including cancer and inflammatory conditions that may involve iron dysregulation, can probably be explained by interaction with external factors such as infectious agents that may affect cellular iron status. Our findings provide both in vivo and in vitro evidence that iron dysregulation mediated by allelic effects of SLC11A 1 may underlie disease susceptibility to infectious and autoimmune conditions. / AFRIKAANSE OPSOMMING: Die opgeloste stof draer familie 11 deel 1 geen (SLC11 A 1) is 'n divalente metaal ioon vervoerder met verskeie pleiotropiese effekte op makrofaagfunksie. Die geen, wat yster reguleer en ook deur sellulêre ystervlakke gereguleer word, is voorheen verbind met verskeie infektiewe en outo-immune siektes. In hierdie studie is in vitro analises, deur middel van die lusiferase verklikker sisteem, asook gevalle-kontrole assosiasie studies gebruik om die rol van SLC11A 1 alleel variasie in pasiënte met diverse siektefenotipes te ondersoek. Vyf verskillende SLC11A 1 promotor variante is geskep vir in vitro studies en gevolg deur transfeksie in U937 en THP-1 sellyne. Die ingevoegde fragmente het twee voorheen beskryfde allele (allele 2 en 3), twee nuwe allele wat in hierdie studie geïdentifiseer is (allele 8 en 9) en In C na T puntmutasie by nukleotied posisie -237 in die teenwoordigheid van alleel 3 ingesluit. Die opvallendste bevinding was die teenoorgestelde effek wat waargeneem is wanneer alleel 3 in die teenwoordigheid van die -237C~ T polimorfisme voorkom, soortgelyk aan alleel 2 uitdrukking. Alhoewel die SLC11A1 geen voorheen geïmpliseer is in yster vervoer, is daar vir die eerste keer aangetoon dat na yster lading, die verskillende allele differensiële uitdrukking van die geen veroorsaak. Verskeie siektes, insluitend slukderm kanker (OC), inflammatoriese dermsiekte (lBO) en oorerflike hemochromatose (HH) (of primêre ysteroorlading), is ondersoek deur middel van assosiasie studies. Betekenisvolle verskille (P<O.05) is waargeneem vir alleel 3 tussen die kontrole- en pasiëntgroepe in al drie siektes wat ondersoek is, maar slegs na stratifikasie volgens die teenwoordigheid van die -237C~ T polimorfisme. Na hersiening van die promotor allele volgens ekspressie profiele verkry met in vitro studies is statisties betekenisvolle assosiasie ook verkry vir alleel 3 met OC en primêre ysteroorlading in vergelyking met die onderskeie populasie kontrolegroepe. Verder is verskeie nuwe variante ook geïdentifiseer in ekson 2 (112G~A, 148deIGACCAGCCC, 157insGACCAGCCCAG) en intron 1 (IVS1- 28C~ T) en 'n statisties betekenisvolle verhoogde frekwensie van variant IVS1- 28C~ T is waargeneem in pasiënte met OC in vergelyking met die populasie kontrolegroep (P<O.05). Die belangrikheid van variasie in die promotor area van die SLC11A 1 geen as 'n modifiserende faktor in ysterverwante siektes, is verder ondersteun deur die SLC11A 1 geen in individue met ysteroorlading in die afwesigheid van homosigositeit vir die HFE C282Y mutasie te ondersoek. Ander gene geassosieerd met yster homeostase, insluitend HFE, SLC11A3, HAMP and DCYTB, is ondersoek in individue met soortgelyke seleksie kriteria en potensiële siekte-verwante mutasies is geïdentifiseer in 11% Wit en 45% Swart Suid-Afrikaanse pasiënte. Die moontlike belang van die SLC11A3 en DCYTB gene in ysteroorlading in die Swart Suid-Afrikaanse populasie en die moontlike betrokkenheid van die DCYTB geen in yster oorlading oor die algemeen, is vir die eerste keer aangetoon. Hierdie studie dra by tot 'n beter insig in die funksie van die SLC11A 1 geen ten opsigte van ystermetabolisme. Die betrokkenheid van SLC11A 1 in 'n reeks siekte fenotipes, wat insluit kanker en inflammatoriese toestande wat verband kan hou met 'n yster wanbalans, kan moontlik verklaar word deur interaksie met eksterne faktore soos infektiewe agente wat die sellulêre yster status kan beïnvloed. Ons bevindinge verskaf beide in vivo en in vitro getuienis dat yster wanbalans, wat bemiddel word deur alleliese effekte van SLC11A1, verantwoordelik mag wees vir vatbaarheid vir infektiewe en outoimmune siekte toestande.

Thesis (M.Sc. Biological Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed April 11, 2008) Includes bibliographical references (p. 245-250)

Thesis (Ph.D.)--Indiana University, 2009. / Title from screen (viewed on August 26, 2009). Department of Microbiology and Immunology, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Mark Kaplan. Includes vita. Includes bibliographical references (leaves 107-125).

Indiana University-Purdue University Indianapolis (IUPUI) / Adaptive and innate immune responses play a critical role in the protection against extracellular or intracellular pathogens. The function of these two types of immune responses is coordinated by CD4+ T-helper (Th) cells. Depending on the cytokine environment, Th progenitor (Thp) cells differentiate into three functionally different effector subsets. T-helper-1 (Th1) cells which mediate cell-mediated immunity, T-helper-2 (Th2) which orchestrates humoral immunity and T-helper-17 (Th17) cells key players in autoimmunity response. Cytokine induced transcription factors that are differentially expressed in Th cells are required for the development and commitment to a specific Th lineage. The population of Th2 cells can be subdivided in subpopulations depending on the level of a cytokine and the subsets of cytokines they produce. Very limited information is available about the regulation of cytokine production in this array of Th2 cells. We have recently identified the ETS family transcription factor PU.1 as regulating heterogeneity in Th2 populations. To define additional factors that might contribute to Th2 heterogeneity, we examined the PU.1 interacting protein IFN-regulatory factor (IRF)-4, a transcription factor expressed in lymphocytes and macrophages. When Th2 cells are separated based on levels of IL-10 secretion, IRF4 expression segregates into the subset of Th2 cells expressing high levels of IL-10. To investigate the role of IRF4 in cytokine heterogeneity, Th2 cells were infected with retrovirus expressing IRF4. The cells overexpressing IRF4 secreted significantly higher levels of IL-10 and IL-4 compared to cells infected with a control vector at the same time the level of IL-9 decreases. To understand the mechanism by which IRF4 regulates IL-10 expression in various Th2 cell subpopulations we used co-immunoprecipitation assays to determine transcription factors that interact with IRF4. Our data shows that PU.1, IRF4 and NFATc2 form a complex in Th2 nuclear extract. We also demonstrated by ChIP assay that IRF4 directly binds the Il10 and Il4 loci in a time dependent manner. The role of these protein-protein and protein-DNA complexes and their contribution towards Th2 heterogeneity will be further defined. Understanding the regulation of the anti-inflammatory cytokine IL-10 in Th2 cells may give us a tool to control inflammation.

Thesis (D. Phil. (Microbiology))--University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Rabies is a fatal but preventable neurotropic disease of potentially all mammals. The disease is caused by lyssaviruses. Rabies is recognized as the 10th most common lethal infectious disease in the world, rendering it one of the most feared zoonotic diseases known to man. Nevertheless, rabies can be prevented by application of pre- or post exposure treatments. Rabies vaccines have been available since the time of Pasteur, more that one hundred years ago. Since, vaccine research focused on the development of safer and more effective vaccines. Topics of current interest in the field of rabies vaccinology were addressed in this study. A primary concern regarding the disease is human mortalities, in the range of 60 000, reported every year. Most of these are linked to exposure to rabid dogs. In addition, a great number of post exposure treatments are administered each year at great costs. Despite availability of efficacious biologics, several factors influence the optimal use and accessibility of these agents in the countries of interest, with cost and availability being the major contributing factors. A proven approach is mass oral vaccination of target animals, such as dogs, which indirectly infers protection to susceptible hosts, including man. Currently available vaccines present several disadvantages of use though, including issues of safety or doubtful stability. Safer but effective alternative vaccines that could be used in oral baits would be valuable. Here the use of two candidate host restricted poxvirus vaccine vectors were explored, particularly also in regard to oral innocuity. The construction, convenient isolation and use of a recombinant Lumpy skin disease virus (Neethling strain) expressing rabies virus glycoprotein in a mouse model were investigated. In addition, a recombinant Modified Vaccinia virus Ankara expressing rabies virus glycoprotein was prepared and tested as a vaccine in mice, dogs and raccoons. In both cases it was clear that the severe attenuation of these viruses did affect the efficacy of the recombinant vaccines in the non-permissive hosts. With the recombinant MVA a clear dosage effect could be shown, and equivalent humoral responses could only be attained at much higher titers of vaccine virus as with replication competent counterparts. Secondly, the cross-protection of rabies vaccines across the spectrum of lyssaviruses was addressed. Lyssaviruses can be divided into two groups based on sequence analysis and pathogenesis. Viruses belonging to the so-called phylogroup II, are the Mokola, Lagos and West Caucasian Bat viruses. Classic rabies biologics fail to fully protect against the viruses attributed to a lack of cross-neutralization. Here, cross-protection and cross-reactive immune responses induced by recombinant vaccinia viruses expressing rabies, Mokola or West Caucasian Bat virus glycoproteins, in single or dual combinations, were investigated. As expected, there was a lack of cross-protection of rabies and Mokola glycoprotein vaccines. There was also a clear lack of cross-protection of West Caucasian Bat virus glycoprotein vaccine and rabies and Mokola viruses. The dual antigen expressing vaccines did not appear to offer any additional protective effect in the tested model. The Mokola virus glycoprotein vaccines induced neutralizing antibody responses that significantly cross-neutralized Lagos Bat virus. / Thesis (PhD (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted