Ulm, Univ., Diss., 2008.

No description available.

No / We have investigated the surface localisation of the phosphotransferase system protein HPr in the equine pathogen Streptococcus equi subsp. equi using immunogold localisation and transmission electron microscopy. Like the LppC acid phosphatase lipoprotein, a reference surface antigen, the S. equi HPR could be clearly detected on the surfaces of intact cells. This study is consistent with previous reports that some streptococcal HPr is cell surface associated and suggests that the extracytoplasmic mobilisation and transfer of phosphate groups by streptococci warrant further investigation.

The aims of this project were to investigate the effect of immune complexes on mononuclear phagocytes in the presence or absence of infection with the human immunodeficiency virus (HIV). Mono Mac 6 (MM6) cells and human monocyte-derived macrophages (MDM) were used to compare the effect of chemical stimulants, cytokines and immune complexes on surface antigen expression. The same experiments were performed using HIV-infected cells to determine the effect of HIV infection on these parameters. Some of the stimulants especially IL-6, IL-10, TNF-alpha and HIV increased CD80 expressions, the effect being greater in MDM than MM6 cells. This has implications for antigen presentation. Cytokines caused the differentiation of MM6 cells and significantly increased or decreased surface antigen expressions. The MM6 cells express surface antigens at lower levels then MDM this indicates that MM6 cells need to differentiate before expressing surface antigens. The high standard deviations obtained meant that no significant change in surface antigen expression was seen in all HIV non-infected and infected MDM incubated with various immune complexes and HIV-sera. Comparing whole blood incubated with KLH and rabbit anti-human IgG showed that both seemed to produce IL-10 and IL-6 early. Only rabbit complexes stimulated TNF-a release. MDM incubated with IL-6, IL-10, and TNF-alpha showed increased expression of CD16 and CD80 only at day 3. However, HIV proteins (CHO) incubated in whole blood caused a significantly release of IL-6 at 8 hours with no detection of IL-10 and TNF-alpha. MM6 infected with HIV-1 Ba-L for 5 days showed increased expression of CD16 and CD11c, but reduced expression of the other antigens examined. Significant levels of IL-10 were released at 8 and 12 hours with a slight increase in IL-6, and TNF-alpha. HIV protein-containing (CHO) immune complexes slightly increased IL-6 secretion at 8 hours at which point, IL-10 production was high. HIV- infected cells incubated with HlV-sera showed a lack of TNF-alpha release but IL-6 and IL-10 was detected at 12 and 8 hours respectively. The detection of high levels of IL-10 and the inhibition of TNF-alpha production may stimulate progression to full blown AIDS.

No / We have investigated the surface localisation of the phosphotransferase system protein HPr in the equine pathogen Streptococcus equi subsp. equi using immunogold localisation and transmission electron microscopy. Like the LppC acid phosphatase lipoprotein, a reference surface antigen, the S. equi HPR could be clearly detected on the surfaces of intact cells. This study is consistent with previous reports that some streptococcal HPr is cell surface associated and suggests that the extracytoplasmic mobilisation and transfer of phosphate groups by streptococci warrant further investigation.

Mycoplasma hyopneumoniae causes swine enzootic pneumonia (SEP) and leads to economic loss worldwide. The mechanism of pathogenesis is still not clear. Since this pathogen remains extracellulary after infection, the surface proteins on M. hyopneumoniae should play very important roles in adhering and affecting tracheal mucosal cells. Therefore, the potential of using the surface proteins as the basic to develop molecular vaccine is currently being investigated. The recombinant clone expressing the 42 kDa protein was isolated from the

The small envelope of hepatitis B virus (HBV) can self-assembles into virus-like particles (VLPs) and they are highly immunogenic. The use of hepatitis B surface antigen (HBsAg) as a vector to deliver foreign CTL epitopes has met with little success due to the constraints of HBsAg stability and secretion imposed by the insertion of foreign sequence into critical regions. In this study, the efficacy of the small HBsAg envelope protein to deliver foreign CTL epitopes using a protective CTL epitope of human respiratory syncytial virus (RSV) was investigated. The strategy of deleting a DNA sequence encoding HBsAg-specific CTL epitopes at different sites and replacing with DNA sequence encoding RSV CTL epitope resulted in recombinant HBsAg DNA immunogens which elicited effector and memory CTL responses in vitro, and RSV protective responses in vivo when these recombinant HBsAg DNAs were used to immunised mice. These data demonstrate the efficacy of HBsAg DNA as a vector for the delivery of disease relevant protective CTL responses. They also suggest the applicability of the approach to derive recombinant HBsAg DNA immunogens simultaneously encoding protective CTL epitopes for multiple diseases. The use of HBsAg VLPs has been used globally as administered vaccine for hepatitis B virus infection makes it an attractive vector candidate to deliver immunogens for other diseases. Since the HBsAg DNAs we tested formed recombinant HBsAg VLPs, our results have implications for the development of vaccination strategies using either recombinant HBsAg DNA or VLP vaccines.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks

No description available.

Les érythrocytes sont un modèle pour l'étude du transport des ions, des nutriments et de divers solutés au travers de la membrane cellulaire. L'identité moléculaire, la régulation et rôle physiologique des canaux ioniques sont pas clairement établis malgré leur implication évidente dans des processus physiologiques comme la sénescence ou pathologiques comme la drépanocytose ou le paludisme. Le présent travail de thèse a fait appel à la technique du 'patch-clamp' et à diverses méthodes biochimiques pour démontrer que: 1/ La diversité des courants anioniques enregistrés au travers de la membrane de l'érythrocyte humain sain, ou infecté par P. falciparum, correspond à différents états d'activité d'un type unique de canal 'maxi-anionique' comportant des niveaux de conductance, des modes d'activation et des propriétés pharmacologiques variables selon les conditions physico-chimiques. 2/ L'identité moléculaire de ce canal anionique est de type 'voltage dependent anion channel (VDAC)'. Il est l'une des trois composantes d'un récepteur 'peripheral-type benzodiazepine receptor (PBR)' présent dans la membrane érythrocytaire. 3/ Le canal VDAC, généralement peu actif correspond, lorsqu'il est activé, à la nouvelle voie de perméation 'new permeability pathway' décrite dans la membrane de l'érythrocyte infecté par P. falciparum. L'activation résulte alors en partie de l'insertion dans la membrane érythrocytaire de protéines plasmodiales de type 'Ring-infected Erythrocyte Surface Antigen (RESA). Ce travail contribue à l'élucidation de la nature exacte des canaux ioniques présents dans la membrane érythrocytaire et avance une hypothèse unificatrice quant au rôle joué par ces canaux.