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Induction of autoantibodies to cathepsin L as a step towards an anti-cancer vaccine.Motsamai, Karabo. January 2005 (has links)
Cancer is a disease that is caused by mutations in somatic cells. Metastasis is the
major cause of death from cancer and often complicates treatment. Malignant
tumours secrete degradative enzymes such as cathepsin L which degrade the
extracellular matrix to facilitate tumour invasion and metastasis.
The immune system does not normally recognize and eradicate tumours because they
arise from self tissues to which the immune system is tolerant. Self antigens are
poorly immunogenic because they lack T cell help. In this study, a foreign glucosidase
was conjugated to self rabbit cathepsin L using glutaraldehyde to
specifically provide T helper cell epitopes. The conjugate was used to immunise two
male rabbits. A second pair of rabbits (male and female), was primed with sheep
cathepsin L (to induce T helper cell activation) and received rabbit cathepsin L
boosters. A third pair of rabbits which served as a control was immunised with sheep
cathepsin L. The two pairs of test rabbits made high avidity antibodies against rabbit
cathepsin L, showing a similar response to control rabbits when antibodies were
tested in an ELISA. Western blot analysis showed that these anti-cathepsin L
autoantibodies were specific for rabbit cathepsin L.
Rabbits which were immunised with the conjugate were · inoculated with sheep
cathepsin L nine weeks after the final inoculation with the conjugate. Analysis of
antibodies in an ELISA showed that antibody responses against rabbit cathepsin L
were augmented in a manner that is characteristic of memory responses. Low titre
antibodies against sheep cathepsin L were also produced. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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Coupling dyes to chicken IgY antibodies for the development of immunodiagnostic tests.Thompson, Janene. January 2003 (has links)
The aim of this study was to develop a highly simplified, sensitive and specific malarial
diagnostic test at the lowest possible cost. Initial work and optimisation of procedures was
achieved with chicken antibodies by covalently attaching commercially available dye to them.
Chicken antibodies were easily isolated from egg yolk and dye is cheap, easily visible and
requires no equipment for identification of results. A dipstick dye-immunoassay was
developed with nitrocellulose as the capture phase. The dye-immunoassay is an alternative to
the traditional enzyme linked immunosorbent assay (ELISA) technique, which employs the
use of an enzyme-substrate reaction.
Numerous dyes were investigated and included Reactive black 5, trypan blue, Cibacron Blue,
Congo red, Acid-black 2, dianix blue, dianix red, para-nitroaniline and primulin. Most of
these dyes have dark colours which are essential for good contrast on nitrocellulose and in a
microtitre plate. Some dyes contain amino (NH2) groups, which are targeted in a covalent
linking step and attached to the lysine residues on antibody molecules or to the carbohydrate
groups on antibody molecules.
Attachment of dye molecules to antibodies with glutaraldehyde was the chief coupling
method explored and conditions were optimized in this study. Unbound dye was removed by
dialysis. Reactive black 5 is sensitive down to 50 nanograms of antigen on nitrocellulose.
A second covalent coupling method was investigated by means of attaching dye to the
carbohydrate moieties on the antibody. Reactive black 5 was sensitive down to 50 nanograms
of antigen. The carbohydrate method appears to be more sensitive than the glutaraldehyde
method at lower antibody concentrations.
Primulin, a yellow dye, was similarly investigated. This dye does not have a dark colour
initially, but can be diazotized to change its colour to orange or purple. It also fluoresces
under ultra-violet light. This dye was sensitive down to 500 nanograms of antigen with both
the glutaraldehyde and carbohydrate coupling techniques.
A dye-linked immunosorbent assay (D-LlSA) protocol for direct antigen detection has been
developed whereby the dye-antibody solution (dianix blue dye) acts as the primary antibody
and substrate respectively. Sensitivity levels compare with traditional ELISAs. Dianix blue is
sensitive down to 25 nanograms of antigen in a microtitre plate.
Unique protein staining abilities of the dyes used in this study were indicated by staining IgY
in electrophoretic gels. Acid-black 2 indicated better protein staining abilities than that of
Coomassie brilliant blue.
Evidence shows that dye was successfully covalently attached to antibodies and that antigen
detection is possible by visualising the dye developed spots. Although malarial antibodies
were not used, all procedures with chicken antibodies were optimised. Highly simplified,
sensitive and specific diagnostic tests were developed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.
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The impact of heavy metals on the aerobic biodegradation of 1,2-dichloroethane in soil.Balgobind, Adhika. January 2009 (has links)
1,2-Dichloroethane (1,2-DCA), a short chain chlorinated aliphatic compound, is one of the most
hazardous toxic pollutant of soil and groundwater, with an annual production in excess of 5.44 × 109 kg.
The major concern over soil contamination with 1,2-DCA stems largely from health risks. Owing to their
toxicity, persistence and potential for bioaccumulation, there is a growing interest in technologies for their
removal. Many sites are, however, co-contaminated with a complex mixture of 1,2-DCA and heavy metal
contaminants. Co-contaminated environments are considered difficult to remediate because of the mixed
nature of the contaminants and the fact that the two components often must be treated differently.
Therefore, the objective of this study was to evaluate the aerobic biodegradation of 1,2-DCA by
autochthonous microorganisms in soil co-contaminated with 1,2-DCA and heavy metals, namely; arsenic
(As3+), cadmium (Cd2+), mercury (Hg2+) and lead (Pb2+), via a direct and quantitative measurement of the
inhibitory effects of heavy metals in a microcosm setting. Effects of various metal concentrations and
their combinations were evaluated based on the following: (i) degradation rate constants; (ii) estimated
minimal inhibitory concentrations (MICs) of metals; (iii) concentrations of heavy metals that caused
biodegradation half-life doublings (HLDs); and (iv) heavy metal concentrations that caused a significant
effect on biodegradation (> 10% increase in t½ of 1,2-DCA). The effects of biostimulation,
bioaugmentation and the addition of treatment additives on the biodegradation process were evaluated.
The presence of heavy metals was observed to have a negative impact on the biodegradation of 1,2-DCA
in both clay and loam soil samples, with the toxic effect being more pronounced in loam soil for all heavy
metal concentrations except for Hg2+, after 15 days. Heavy metal concentrations of 75 mg/kg As3+,
840 mg/kg Hg2+, and 420 mg/kg Pb2+, resulted in 34.24%, 40.64%, and 45.94% increases in the t½ of
1,2-DCA, respectively, in loam soil compared to clay soil. Moreover, the combination of four heavy
metals in loam soil resulted in 6.26% less degradation of 1,2-DCA compared to clay soil, after 15 days.
Generally, more than 127.5 mg/kg Cd2+, 840 mg/kg Hg2+ and 420 mg/kg of Pb2+ was able to cause a >
10% increase in the t½ of 1,2-DCA in clay soil, while less than 75 mg/kg was required for As3+. An
increased reduction in 1,2-DCA degradation was observed with increasing concentration of the heavy
metals. In clay soil, a dose-dependant relationship between k1 and metal ion concentrations in which k1
decreased with higher initial metal concentrations was observed for all the heavy metals tested except
Hg2+. Ammonium nitrate-extractable fractions of bioavailable As3+ and Cd2+ concentrations varied
greatly, with approximately < 2.73% and < 0.62% of the total metal added to the system being
bioavailable, respectively. Although bioavailable heavy metal fractions were lower than the total metal
concentration added to the system, indigenous microorganisms were sensitive to the heavy metals.
Biostimulation, bioaugmentation and amendment with treatment additives were all effective in enhancing
the biodegradation of 1,2-DCA in the co-contaminated soil. In particular, biostimulation with fertilizer,
dual-bioaugmentation and amendment with CaCO3 were most efficient in enhancing 1,2-DCA
degradation resulting in 41.93%, 59.95% and 51.32% increases in the degradation rate constant of
1,2-DCA in the As3+ co-contaminated soil, respectively, after 20 days. Among all the treatments, dualbioaugmentation
produced the highest 1,2-DCA degrading population of up to 453.33 × 107 cfu/ml in the
Cd2+ co-contaminated soil. On comparison of the As3+ and Cd2+ co-contaminated soil undergoing either
biostimulation or dual-bioaugmentation, similarity in the denaturing gradient gel electrophoresis (DGGE)
banding patterns was observed. However, the banding patterns for the different bioremediation options
demonstrated a difference in bacterial diversity between the fertilized and dual-bioaugmented samples.
DGGE profiles also indicate that while numerous bands were common in the fertilized co-contaminated
soils, there were also changes in the presence and intensity of bands due to treatment and temporal
effects. Dehydrogenase and urease activities provided a more accurate assessment of the negative impact
of heavy metals on the indigenous soil microorganisms, resulting in up to 87.26% and 69.58% decreases
in activities, respectively. In both the biostimulated and bioaugmented soil microcosms, dehydrogenase
activity appeared biphasic with an initial decrease followed by an increase in the treated soils over time.
Results from this study provide relevant information on some alterations that could be introduced to
overcome a critical bottle-neck of the application of bioremediation technology. In conclusion, the
bioremediation strategies adopted in this study may be used as a rational methodology for remediation of
sites co-contaminated with 1,2-DCA and heavy metals, subject to a thorough understanding of the
microbial ecology and physico-chemical parameters of the site. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.
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Biotyping Saccharomyces cerevisiae strains using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)Moothoo-Padayachie, Anushka. January 2011 (has links)
In clinical diagnosis and fermentation industries there is a need for a method that allows for the
differentiation of yeast to the strain level (biotyping). The ideal biotyping method should be
accurate, simple, rapid and cost-effective, and capable of testing a large number of yeast
isolates. Matrix assisted laser desorption/ionization time of flight mass spectrometry has
emerged as a powerful biotyping tool for the identification of bacteria and clinical yeast isolates,
mainly Candida. It has been found that the MALDI-TOF MS signals from yeast are harder to
obtain than from bacteria. It has been reported by several research studies that a cell lysis step
is required to obtain a mass spectral signal for clinical Candida strains. To date an optimized
sample preparation protocol has not been devised for the biotyping of S. cerevisiae strains.
Studies on the identification of yeast using MALDI-TOF MS have focused primarily on clinical
Candida yeast isolates but have included very few S. cerevisiae strains. Furthermore these
yeast identification studies using MALDI-TOF MS have only achieved identification to the
species and not strain level. A major limiting attribute of MALDI-TOF MS for the accurate
identification of microbes, is its dependency on a comprehensive mass spectral database.
Bruker Daltonics is a pioneer and leader in providing innovative life science tools based on
mass spectrometry thus the Bruker Daltonics mass spectral database and state-of-the-art
instruments and accompanying software were selected for this study. The Bruker Daltonics
mass spectral database currently holds three thousand seven hundred and forty
microorganisms of which only a mere seven are S. cerevisiae strains.
Initially in this study, a number of parameters of a generic ethanol/formic acid protein
extraction procedure as originally described by Bruker Daltoincs were considered in the
development of a sample preparation protocol that yielded characteristic and highly
reproducible MALDI-TOF mass spectra. The parameters considered included cell number,
alcohol fixation, matrix solution and media. It was found that using the optimized sample
preparation protocol unique and highly reproducible mass spectral profiles were obtained for all
three S. cerevisiae strains. Multivariate analysis confirmed that the differences between all three
S. cerevisiae strains were statistically significant. For quality assurance, the spectra of the three
strains were sent for evaluation by Bruker Daltonics and were deemed suitable for the purpose
of biotyping.
The newly created ethanol/formic acid extraction procedure was used to generate an S.
cerevisiae mass spectral database comprising of forty-five S. cerevisiae strains within a local
context but also of global significance. The accuracy of the mass spectral database was
assessed using blind coded S. cerevisiae strains obtained from the Agricultural Research
Council Infruitec-Nietvoorbij (Institute for Deciduous Fruit, Vines and Wine), Stellenbosch, South
Africa. It was found that S. cerevisiae identification to the species and more importantly strain
level was achievable with relatively good accuracy. To determine the potential application of
MALDI-TOF MS as an accurate method for S. cerevisiae strain identification in industry, blind
coded S. cerevisiae strains were obtained from Natal Cane Products and subjected to MALDITOF
MS analysis. It was found that four of the pure cultures submitted were correctly identified
to the strain level and the three S. cerevisiae strains incorrectly identified may have been
contaminants or the result of incorrect optimization conditions for the fermentation. Thus MALDITOF
MS was shown to be an accurate identification tool, that may also be used to detect
contaminants or incorrect environmental conditions which can result in substantial losses. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
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The effect of Wnt isoforms on myogenesis.McColl, Rhys Stewart. 02 September 2014 (has links)
Satellite cells are muscle stem cells that are responsible for the growth and repair of
skeletal muscle tissue. Satellite cells typically exist in a quiescent state in their niche
between the sarcolemma and basal lamina. In response to muscle tissue injury, activated
satellite cells, otherwise known as myoblasts, migrate to the site of injury where they
proliferate and subsequently differentiate and fuse to repair damaged myofibers. The
success of muscle growth and repair is highly dependent on the speed and degree to which
these myoblasts migrate, proliferate and differentiate. This overall process, referred to as
myogenesis, is largely controlled by the myogenic regulatory factors, a group of basic helixloop-
helix transcription factors including MyoD, Myf5, myogenin and Mrf4. It has
recently been found that the Wnt family of secreted signalling proteins are highly involved
in the regulation of developmental processes such as myogenesis. Wnt proteins are a
family of 21 highly-conserved, secreted, cysteine-rich signalling molecules which are found
in all multi-cellular organisms. Wnt signalling is highly versatile and is initiated by the
binding of extracellular Wnt to cell-surface Frizzled receptors (Fz). It is highly dependent
on both the Wnt isoform and Fz type and may initiate one of three known signalling
pathways. Wnt3A and Wnt7A are of particular interest as they have previously been
linked with myogenesis. C2C12 myoblasts over-expressing Wnt3A have been seen to have
reduced levels of motility and terminal differentiation. Wnt7A is suspected to maintain a
healthy satellite cell pool by regulating self-renewal; injection of recombinant Wnt7A into
mouse leg muscle resulted in increased satellite cell numbers. In vitro Wnt studies have
typically involved the treatment of mouse cells with conditioned medium containing Wnt,
often at unknown concentrations. In our study we wished to test the effects of known
concentrations of recombinant Wnt3A and Wnt7A on mouse C2C12 and donor-derived
human skeletal muscle myoblasts (HSkM) in vitro. Wnt3A and Wnt7A were seen to
increase the rate of C2C12 migration in a dose dependent manner. HSkM cells treated
with 10 ng/ml Wnt3A also displayed increased motility. Neither Wnt3A nor Wnt7A were
seen to have any significant effects on the proliferation of C2C12 or HSkM cells. Wnt3A
(10ng/ml and 100 ng/ml) but not Wnt7A was seen to decrease C2C12 terminal
differentiation as measured by expression of myosin heavy chain (MyHC). Subsequent
confocal microscopy revealed that Wnt3A significantly reduced the percentage of MyoD+
C2C12 nuclei during differentiation. A reduction in nuclear MyoD would support the
observed impaired commitment to differentiation. However, donor-derived human
skeletal muscle myoblasts treated with 10 ng/ml Wnt3A were not seen to have significantly
reduced nuclear MyoD levels or terminal differentiation; the reason for this is unclear but
may relate to a number of factors including the concentration of Wnt, Fz and co-receptor
profiles and the presence of specific extracellular matrix and serum factors. These studies
provide new insight into the role of Wnts in myogenesis and lay the foundation for future
work on Wnt3A and Wnt7A. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.
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Studying trypanosomal peptidase antigen targets for the diagnosis of animal African trypanosomiasis.Eyssen, Lauren Elizabeth-Ann. 09 September 2014 (has links)
The lack of a vaccine candidate due to antigenic variation by trypanosomal parasites, the causative agents of human and animal African trypanosomiasis, requires the disease to be controlled by surveillance, diagnosis and appropriate treatment schedules. Due to the non-specific symptoms along with the toxicity and side effects of the current trypanocides, diagnosis needs to be accurate, cost effective and applicable to active case finding in mostly rural settings. Trypanosomal proteases have been identified as virulence factors as they are essential to the parasites‟ survival. Here the diagnostic potential of previously described virulence factors, oligopeptidase B (OPB), pyroglutamyl peptidase (PGP) and the full length and catalytic domain of the cathepsin L-like peptidases (CATLFL and CATL respectively) from T. congolense (Tc) as well as OPB and CATL from T. vivax (Tv), was determined. These antigens were recombinantly expressed, purified and used to generate antibodies in chickens. The purified recombinant antigens were tested in an inhibition and indirect ELISA format using two separate blinded serum panels consisting of sera from non-infected and experimentally infected cattle, one each for T. congolense and for T. vivax. The tested sera were diluted 1:10 for the TcCATLFL, TcCATL antigens whilst the TvCATL antigen used a 1:100 serum dilution. The TcCATLFL, TcCATL and TvCATL antigens had the highest diagnostic potential in the indirect ELISA format with a 90.91, 92.21% accuracy at the second cut-off and a 77.22% accuracy at the third cut-off along with 0.8084, 0.7785 and 0.8813 area under curve (AUC) values respectively. These antigens show potential for development of lateral flow tests to detect T. congolense and T. vivax infections in cattle. The recently discovered metacaspases (MCAs) have been implicated in caspase-like activity and differentiation in T. b. brucei, T. cruzi and L. major and are considered to be virulence factors. The putative metacaspase 5 gene from T. congolense (TcMCA5) was successfully cloned, expressed within inclusion bodies, resolubilised and refolded using immobilised metal affinity chromatography. Recombinant TcMCA5 was successfully refolded as evident by the hydrolysis of the synthetic peptide substrate, Z-Gly-Gly-Arg-AMC. Autocatalytic processing was observed within the inclusion bodies and the products were purified along with the full length recombinant protein. Anti-TcMCA5 IgY antibodies, raised in chickens, were able to detect the native TcMCA5 along with the autocatalytic processed products within the lysate of the procyclic T. congolense (strain IL 3000) parasites. The diagnostic potential of TcMCA5 still requires verification. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
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In vitro anti-oxidative and carbohydrates digesting enzymes inhibitory effects of some medicinal plants used for the management of diabetes in the Mrewa district, Zimbabwe.Chipiti, Talent. 12 September 2014 (has links)
Abstract available on PDF file. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.
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Ecophysiological studies of the invasive weed Chromolaena odorata (L.) King and Robinson and its control in KwaZulu-Natal.Naidoo, Kubendran Kista. 15 September 2014 (has links)
Despite increased interest in the control and spread of the alien weed, Chromolaena odorata, little is known of its photosynthetic characteristics under field conditions. The aim of the study was to obtain a better understanding of the ecophysiological attributes of C. odorata that contribute to its invasive success.
Photosynthetic performance of C. odorata was evaluated by monitoring diurnal changes in gas exchange, chlorophyll a fluorescence and plant water relations. Gas exchange characteristics of plants growing in exposed and shaded environments, as well as seasonal patterns, were evaluated. The response of C. odorata to water stress was also determined.
Chromolaena odorata exhibited high CO2 uptake rates with no light saturation. Shade plants had significantly larger leaf surface areas and greater concentrations of total chlorophyll, total carotenoids and chlorophylls a and b than sun plants. Relatively high photosynthetic uptake rates in C. odorata may allow for greater carbon gain in high light environments thus contributing to increased growth and spread of the species. Chromolaena odorata can successfully acclimatise to low photosynthetic photon flux density (PPFD), thus, outcompeting less tolerant species under low light conditions.
Leaf conductance, CO2 uptake, transpiration and chlorophyll fluorescence parameters in winter were tightly coupled to summer. Plants had higher water use efficiency (WUE) in summer compared to winter, probably to maximise CO2 uptake and minimise water loss.
There was a progressive decrease in leaf water potential with increase in water stress in water stressed (WS) plants. The leaves of WS plants showed signs of severe wilting 10 days after the onset of stress compared to well watered (WW) plants. Increased proline concentration and leaf wilting probably increase (WUE) and may be an adaptive strategy to protect against dehydration injury.The effects of the herbicide, glyphosate, on gas exchange and translocation were studied. Glyphosate treatment decreased leaf conductance leading to a reduction in CO2 uptake and transpiration. Glyphosate is a mobile herbicide that is transported from leaves to roots and caused death of plants within a week of treatment.
The potential antimicrobial properties of the weed were evaluated using selected bacteria and fungi. Crude leaf extracts exhibited some antibacterial and antifungal activity. Extracts from the weed are unlikely to be useful antimicrobial sources due to low concentrations of active compounds.
A co-ordinated strategy, taking into account the high plasticity of the weed, is needed to curtail the spread of C. odorata. The ecophysiological responses to environmental conditions should be considered when planning management and control strategies for C. odorata. / Ph.D. University of KwaZulu-Natal, Durban 2013.
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Development of an alternative non-obese non-genetic rat model of type 2 diabetes using caffeine and streptozotocin.Naidoo, Pragalathan. January 2013 (has links)
The aim of the present study was to develop an alternative non-obese non-genetic rat model of type 2 diabetes (T2D). Six-week-old male Sprague-Dawley rats were randomly divided into six groups, namely: Normal Control (NC), Diabetic Control (DBC), Caffeine 5 mg/kg BW + STZ (CAF5), Caffeine 10 mg/kg BW + STZ (CAF10), Caffeine 20 mg/kg BW + STZ (CAF20) and Caffeine 40 mg/kg BW + STZ (CAF40) and were fed a commercially available rat pellet diet and normal drinking water ad libitum throughout the 13 weeks experimental period. After a one week acclimatization period, diabetes was induced in the animals in DBC and all CAF groups with an injection (i.p.) of the respective dosages of caffeine (mg/kg BW) 15 min before the injection (i.p.) of STZ (65 mg/kg BW) when normal saline was injected to the DBC group instead of caffeine. The NC group received normal saline and citrate buffer instead of caffeine and STZ, respectively. One week after the STZ injection, animals with non-fasting blood glucose > 300 mg/dl were considered as diabetic. Three weeks after the STZ injection, the animals in the CAF5 and CAF10 groups were eliminated from the study due to the severity of diabetes and the experiment was continued with the remainder groups for a 13 weeks period. At the end of the experimental period the rats were euthanized and blood and organ samples were collected for subsequent analysis. The data of daily food and fluid intake, weekly body weight and blood glucose, oral glucose tolerance test, serum insulin, fructosamine, lipid profile, organ specific and antioxidative enzymes, anti-diabetic drug response tests, and liver, heart, kidney and pancreas histopathology suggest that the CAF20 group can be a new and alternative non-obese non-genetic chemically-induced model for T2D and can be therefore used for both chronic and acute research studies as well as pharmacological screening of new anti-diabetic drugs. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.
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Recombinant expression of, and characterisation of antibodies against variable surface glycoproteins : LiTat 1.3 and LiTat 1.5 of Trypanosoma brucei gambiense.Mnkandla, Sanele Michelle. 21 July 2014 (has links)
Human African Trypanosomiasis (HAT), also known as sleeping sickness is one of the many life threatening tropical diseases posing a serious risk to livelihoods in Africa. The disease is restricted to the rural poor across sub–Saharan Africa, where tsetse flies that transmit the disease, are endemic. Sleeping sickness is known to be caused by protozoan parasites of the genus Trypanosoma brucei, with the two sub-species: T. b. gambiense and T. b. rhodesiense, responsible for causing infection in humans. The disease develops in two stages, firstly, the infection is found in the blood and secondly, when the parasites cross the blood-brain barrier entering the nervous system. To date, no vaccines have been developed, however, there is a range of drugs and treatments available which depend on the type of infection (T. b. gambiense or T. b. rhodesiense) as well as disease stage.
The trypanosome parasites have a two-host life cycle i.e. in the mammalian host as well as the tsetse fly vector. Throughout the cycle, the parasite undergoes changes, one of them being the acquisition of a variable surface glycoprotein (VSG) coat prior to entry into the human host bloodstream. Once in the host, the infection progresses and through a phenomenon known as antigenic variation, the parasite expresses a different VSG coat periodically, enabling the parasites to constantly evade the host’s immune response, facilitating their survival. The VSG genes coding for the proteins are activated by an intricate process involving the encoding of a gene which is kept silent, until activated in one of several expression sites. Despite the constant switching of VSG surface coats, there are VSG forms that are predominantly expressed in T. b. gambiense namely VSGs LiTat 1.3, LiTat 1.5 and LiTat 1.6 which are used in diagnostic tests, as antigens to detect antibodies in infected sera of HAT patients. The acquisition of these VSG antigens is, however, of high risk to staff handling the parasites, and so the first part of the study was aimed at cloning, recombinantly expressing and purifying the two VSGs known to be recognised by all gambiense HAT patients: LiTat 1.3 and LiTat 1.5, for possible use as alternative antigens in diagnostic tests. The genes encoding both VSGs, LiTat 1.3 and LiTat 1.5, were first amplified from either genomic or complementary DNA (gDNA or cDNA), cloned into a pTZ57R/T-vector and sub-cloned into pGEX or pET expression vectors prior to recombinant expression in E. coli BL21 DE3 and purification by Ni-affinity chromatography. Amplification and subsequent cloning yielded the expected 1.4 kb and 1.5 kb for the LiTat 1.3 and LiTat 1.5 genes respectively. Recombinant expression in E. coli was only successful with the constructs cloned from cDNA, i.e. the pGEX4T-1-cLiTat 1.3 and pET-28a-cLiTat 1.3 clones. Purification of the 63 kDa cLiTat 1.3His protein following solubilising and refolding did not yield pure protein and there were also signs of protein degradation. For comparison, expression was also carried out in P. pastoris and similar to the bacterial system, expression was only successful with the LiTat 1.3-SUMO construct yielding a 62.7 kDa protein. Purification of LiTat 1.3SUMO also surpassed that of cLiTat 1.3His with no degradation. The diagnostic tests based on VSGs LiTat 1.3 and LiTat 1.5 as antigens operate by binding with antibodies in infected sera, to confirm infection. These antibody detection tests have their limitations, hence an alternative would be antigen detection tests, which use antibodies to detect the respective antigens in infected sera. The second part of the study therefore involved antibody production, where chickens were immunised with the native VSGs LiTat 1.3, LiTat 1.5 as well as recombinant RhoTat 1.2 (a VSG expressed in T. evansi). Antibody production was analysed by ELISA and characterised by western blotting, prior to immunolabelling of T. b. brucei Lister 427 parasites. The chicken IgY showed a response to the immunogens, and were able to detect their respective proteins in the western blot. Interestingly, the anti-nLiTat 1.3, anti-nLiTat 1.5 and anti-rRhoTat 1.2 antibodies were able to detect their respective VSGs on the T. b. brucei trypanosome parasites in the immunofluorescence assay, thus demonstrating cross reactivity. As the antibodies showed specificity, they could potentially detect antigens in infected sera of HAT patients in an antigen detection based test. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
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