Theses and Dissertations
Permanent URI for this collection
Browse
Browsing Theses and Dissertations by Issue Date
Now showing 1 - 20 of 100
Results Per Page
Sort Options
Item Open Access Drug Resistance Mutations in Naive HIV-1 South African Patients, and Construction of Molecular Clones to Phenotype Putative Resistance Mutations(2009-03) Mavhandu, Lufuno Grace; Bessong, P. O.; Rekosh, David; Hammarskjold, Marie-LouiseSee the attached abstract belowItem Open Access In-vitro bioactivity of fractions from a local medicinal plant on HIV-1 replication, and selected fungal and bacterial pathogens(2009-03) Mutshembele, Awelani Mirinda; Bessong, Pascal O.; Eloff, Jacobus N.; Obi, LarrySee the attached abstract below.Item Open Access Detection of Cryptosporidium species in stools of HIV/AIDS patients in Bela-Bela, South Africa(2010-06) Makuwa, Stenly Modupi; Bessong, P. O.; Samie, A.; Potgieter, N.See the attached abstract belowItem Open Access Genetic characterization of human immunodeficiency virus from Northern South Africa(2012-12-19) Iweriebor, Benson Chuks; Bessong, Pascal Obong; Mphahlele, Jeffrey; Moyo, Sylvester RodgersItem Open Access Immunodulation of inflammation in a murine pnemococcal sepsis model(2013-10-01) Musie, Mbulaheni Edgar; Bessong, P. O.; Scheld, M. W.Item Open Access Studies on human immunodeficiency virus genetic drug resistance and subtype distribution in Northern South Africa(2014-01-10) Nwobegahay, Julius; Bessong, Pascal O.; Selabe, GloriaItem Open Access Prevalence and molecular characterization of enteric viruses and their association with malnutrition in children less than two years old in the Vhembe Region of Limpopo Province, South Africa(2014-01-10) Shivambu, Nurse; Samie, Amidou; Bessong, PascalItem Open Access Expression of an active HIV-1 subtype C protease(2014-11-03) Tambani, Tshifhiwa; Bessong, Pascal. O.; Tebit, Denis.Item Open Access Molecular diagnosis and characterization of clinical isolates of entamoeba histolytica, giadia lamblia and cyptosporidium species from the United Arab Emirates and South Africa(2014-11-03) ElBakri, Ali Mohammed Kamal; Bessong, P. O.; Potgieter, N.; AbuOdeh, R. OItem Open Access Molecular detection of norovirus GI ang GII genotypes in children less than two years of age and impact on child growth(2014-11-03) Moloro, Glenton Thabo; Samie, A.; Bessong, P. O.Item Open Access Studies on HIV-1 subtype c drug susceptibility : development of a phenotypic resistance assay and evaluation of plant-derived compounds(2014-11-03) Mavhandu, Lufuno Grace; Bessong, Pascal. Obong; Rekosh, David.; Hammarskjold, Marie-LouItem Open Access Prevalence and molecular identification of candida oral infections in HIV patients attending treatment centres, Vhembe District, Limpopo Province(2014-11-03) Mashao, Mmbangiseni Beauty; Samie, A.Item Open Access HIV co-infections with cytomegalovirus, hepatitis c virus and human papillomavirus in northern South Africa(2014-11-03) Rikhotso, Mikateko; Bessong, P. O.; Tebit, Denis.Item Open Access Characterization of heat shock protein 70-z (PfHsp70-z) from plasmodium falciparium(2015) Zininga, Tawanda; Shonhai, Addmore; Burger, A.Malaria is a parasitic disease that accounts for more than 660 thousand deaths annually, mainly in children. Malaria is caused by five Plasmodium species P. ovale, P. vivax, P. malariae, P. falciparum and P. knowlesi. The most lethal cause of cerebral malaria is P. falciparum. The parasites have been shown to up-regulate some of their heat shock proteins (Hsp) in response to stress. Heat shock protein 70 (called DnaK in prokaryotes) is one of the most prominent groups of chaperones whose role is central to protein homeostasis and determines the fate of proteins. Six Hsp70 genes are represented on the genome of P. falciparum. The Hsp70 genes encode for proteins that are localised in different sub-cellular compartments. Of these two occur in the cytosol, PfHsp70-z and PfHsp70-1; two occur in the endoplasmic reticulum, PfHsp70-2 and PfHsp70-y; one in the mitochondria, PfHsp70-3 and one exported to the red blood cell cytosol, PfHsp70-x. PfHsp70-1 is a well characterized canonical Hsp70 involved in prevention of protein aggregation and facilitates protein folding. Little is known about PfHsp70-z. PfHsp70-z was previously shown to be an essential protein implicated in the folding of proteins possessing asparagine rich repeats. However, based on structural evidence PfHsp70-z belongs to the Hsp110 family of proteins and is thought to serve as a nucleotide exchange factor (NEF) of PfHsp70-1. The main aim of this study is to elucidate the functional roles of PfHsp70-z as a chaperone and its interaction with PfHsp70-1. In the current study, PfHsp70-z was cloned and expressed in E. coli JM109 cells. This was followed by its purification using nickel chromatography. The expression of PfHsp70-z in parasites cultured in vitro was investigated and its association with PfHsp70-1 was explored using a co-immuno precipitation assay. PfHsp70-z expression in malaria parasites is up regulated by heat stress and the protein is heat stable based on investigations conducted using Circular Dichroism. Furthermore, the direct interaction between recombinant forms of PfHsp70-z and PfHsp70-1 were investigated using slot blot and surface plasmon resonance assays. PfHsp70-z was observed to exhibit ATPase activity. In addition, the direct interaction between PfHsp70-z and PfHsp70-1 is promoted by ATP. Based on limited proteolysis and tryptophan fluorescence analyses, PfHsp70-z binds ATP to assume a unique structural conformation compared to the conformation of the protein bound to ADP or in nucleotide-free state. PfHsp70-z was able to suppress the heat-induced aggregation of malate dehydrogenase and luciferase in vitro. Interestingly, while ATP appears to modulate the conformation of PfHsp70-z, the chaperone function of PfHsp70-z was not influenced by ATP. Altogether, these findings suggest that Characterization of Heat Shock Protein 70-z (PfHsp70-z) from Plasmodium falciparum iii PfHsp70-z serves as an effective peptide substrate holding chaperone. In addition, PfHsp70-z may also serve as the sole nucleotide exchange factor of PfHsp70-1. The broad spectrum of functions of this protein, could explain this PfHsp70-z is an essential protein in malaria parasite survival. This is the first study to show that PfHsp70-z possess independent chaperone activity and that it interacts with its cytosolic counterpart, PfHsp70-1 in a nucleotide dependent fashion. Furthermore, the study shows that PfHsp70-z is a heat stable molecule and that it is capable of forming high order oligomers.Item Open Access Application of cloning in the detection of HIV-1 and drug resistant minority populations(2015-01-14) Hatyoka, Luiza Miyanda; Bessong, T. M.; Masebe, Tracy. M.Item Open Access Screening of herbal preparation (Pheko) for anti HIV-1 replication properties(2015-01-14) Matume, Nontokozo Daphney; Bessong, P. O.; Sekhoacha, M.Item Open Access The use of Water Point Mapping (WPM) as a tool to assess improved water resources in rural communities(2015-05) Taonameso, Solomon; Potgieter, N.; Mudau, L. S.See the attached abstract belowItem Open Access Construction of an HIV-1 subtype C ventor system for phenotypic drug resistance studies(2015-07-16) Phathagi, Muendi Tshililelwa; Bessong, P. O; Folefoc, AItem Open Access Characterization of HIV-1 drug resistance mutations from plasma and peripheral mononuclear cells in patients failing antiretroviral treatment in Bela-Bela, South Africa(2015-09-16) Etta, Elisabeth Mashu; Bessong, Pascal Obong; Tebit Denis MangaItem Open Access Characterization of PFF1010c, a type IV Plasmodium fasciparum heat shock protein 40(2016) Mutavhatsindi, Hygon; Shonhai, A.; Burger, A.Malaria is caused by protozoa of the genus Plasmodium. Malaria accounts for approximately more than half a million deaths yearly. Of the five species of Plasmodium, P. falciparum accounts for the most deadly form of the disease. P. falciparum survives under various physiological conditions during its life cycle. The parasite employs its molecular chaperones machinery particularly heat shock proteins (Hsps) to protect its protein constituents during physiological stress. Hsps are conserved molecules that constitute a major part of the cell’s molecular chaperone system. P. falciparum Hsps play an important cyto-protective role guaranteeing that the malarial parasite survives under the severe conditions that prevail in the host environment. PFF1010c is a type IV P. falciparum heat shock protein 40. PFF1010c is predicted to be expressed only at the gametocyte stage of the malarial parasite’s life cycle. The aim of the current study was to investigate the expression PFF1010c by parasites and the gametocyte stage as well as characterize the structure-function features of the protein. PFF1010c was successfully expressed in E. coli cells. Despite successful expression of the protein, its purification proved problematic. The attempt to purify PFF1010c was carried out under both native and denaturing conditions. Far Western blot analysis to investigate direct interaction between PFF1010c and PfHsp70-1 was conducted and no interaction was observed. Malarial parasites were harvested at different stages and total protein was isolated. The expression of PFF1010c was confirmed to occur at the gametocyte stage of the parasite’s development using Western blot analysis. This study confirmed that PFF1010c is only expressed at the gametocyte stage of the malarial parasite. Furthermore, PFF1010c was not expressed at the asexual stage. Possible interactors of PFF1010c were predicted by STRING, a bioinformatics based tool. The expression of PfHsp90, PfHop and PfHsp70-1 at the gametocyte stage was investigated and confirmed by Western blot analyses.