No description available.

No description available.

Thesis (MSc ( Veterinary Tropical Diseases, Veterinary Science))--University of Pretoria, 2007. / Includes bibliographical references. Also available in print format.

Thesis (Ph.D.)--Murdoch University, 2009. / Thesis submitted to the Faculty of Health Sciences. Includes bibliographical references (leaves 183-209)

African trypanosomiasis is a widespread disease of livestock which is a major constraint to livestock production, mixed farming and the rural economy. The Jos Plateau in Nigeria was historically free of tsetse flies and trypanosomiasis and this lack of disease attracted large numbers of cattle keeping pastoralists. The area now plays an important role in the national/regional cattle industry, holding 300,000 pastoralists and over a million cattle, ~ 7% of the national herd. However, over the past twenty years tsetse flies have (re)invaded the Jos plateau and trypanosomiasis is now a significant problem. Little is known about the distribution and overall prevalence of the disease across the Jos plateau or about the habits and customs that could affect the epidemiology of the disease in this area. This knowledge is essential if successful interventions to reduce its impact are to be put in place. To bridge this gap, a longitudinal two stage cluster survey was carried out in 2008 to determine the prevalence of bovine trypanosomiasis. The study showed that the prevalence of trypanosomiasis across the Jos plateau was 46.8% (39.0 – 54.5%) with no significant seasonal variation. T. b. brucei was present at a prevalence of 3.3% (1% – 5.5%); T. congolense savannah at a prevalence of 27.7% (21.8% - 33.6%); T. vivax at a prevalence of 26.7% (18.2% - 35.3%). Although there was no significant seasonal variation in prevalence across the Jos plateau, seasonal variations were observed at village level to create 3 distinct groups. Group 1 villages (50.0%) which followed the expected pattern of low prevalence in the dry season and high prevalence in the wet season; Group 2 villages (16.7%) where there was no seasonal variation; Group 3 villages (33.3%) where paradoxically the prevalence was higher in the dry season and lower in the wet season. This reversed epidemiological pattern is attributed to the harsh climatic conditions of the dry season which reduce resistance to infection in cattle and increase vector – host contact. Migration was shown to be a significant risk factor for trypanosomiasis infection and the dry season was shown to significantly increase the effect of all risk factors. Participatory rural assessment was also conducted to investigate socio – economic factors and knowledge, attitudes and practices concerning tsetse and trypanosomiasis. The results of the participatory rural assessment exercise show that trypanosomiasis is well recognised by farmers on the Jos plateau. They are aware of the animal health and production disadvantages associated with it and make considerable efforts to control it, along with other livestock diseases. However, they lack the adequate knowledge to effectively control these diseases themselves and there are gaps in veterinary service provision. Wealth ranking showed that the majority of pastoralists in the study were either in the ‘middle’ or ‘better – off’ groups. Only 6.1% were classed as poor. Anaemia as an indicator for trypanosomiasis was investigated and FAMACHA charts were evaluated as a potential penside test for anaemia. Results show that anaemia in cattle on the Jos Plateau is not strongly related to trypanosomiasis and that the FAMACHA chart is a poor test for anaemia in cattle.

No description available.

Based on thesis - University of Michigan. / "Reprinted from the American journal of tropical medicine, vol. 29, no. 3, May, 1949."

Thesis (MSc (Veterinary Science))--University of Pretoria, 2004. / Includes bibliographical references.

The primary structure of a 38 kDa protein isolated from membrane preparations of African trypanosomes (Trypanosoma brucei rhodesiense) was determined by protein and DNA sequencing. Searching of the protein database with the trypanosome translated amino acid sequence identified glycerol 3-phosphate dehydrogenase (EC 1.1.1.8) from various prokaryotic and eukaryotic organisms as the optimal scoring protein. Surprisingly, the eukaryotic trypanosome enzyme showed the highest degree of sequence identity with the corresponding enzyme from the prokaryote Escherichia coli. Using recombinant DNA techniques, the trypanosome molecule was expressed in Escherichia coli and found to be enzymatically active, thus confirming the identity of the molecule as an NAD+-dependent glycerol 3-phosphate dehydrogenase. A monoclonal antibody specific for the 38 kDa protein was used to localize the enzyme to glycosomes. The enzyme has a pi of 9.0, a net charge of +9 at physiological pH and contains the peroxisome-like targeting tripeptide SKM at its C-terminus, all characteristic of glycosomal enzymes. Amino acids predicted to be involved in the NAD+-dependent glycerol 3-phosphate dehydrogenase active site have diverged from those of the mammalian enzyme. Kinetic analyses of the trypanosome GPD and GPD from rabbit muscle showed that the Km values of the two enzymes are different The data suggests that the trypanosome protein may be a candidate target for rational drug design. Northern and Southern blot analyses showed that the trypanosome NAD+-dependent glycerol 3- phosphate dehydrogenase was translated from a single transcript and that only two gene copies exist thus making this molecule an attractive target for knockout mutagenesis. A second molecule, an abundant 11 kDa membrane protein, was also purified from African trypanosomes. This protein cross-reacted with monoclonal antibodies originally generated against the lipophosphoglycan-associated protein of Leishmania donovani. Immunoblot analysis showed that the 11 kDa molecule was present in a variety of species of kinetoplastids. It was found in several species and subspecies of African trypanosomes and was present in low amounts in bloodstream forms and in larger amounts in procyclic, epimastigote and metacyclic life cycle stages. The molecule was present in procyclic trypanosome membranes at approximately [special characters omitted] molecules per cell. Its wide distribution in kinetoplastids and its membrane disposition suggested a name for this class of molecules (kinetoplastid membrane protein-11) and for the molecule characterized in this thesis (trypanosome kinetoplastid membrane protein-11). The kinetoplastid membrane protein-11 molecule was purified from Trypanosoma brucei rhodesiense by organic solvent extraction and octyl-Sepharose chromatography and a 14 amino acid internal peptide sequence was obtained by gas phase microsequencing. This sequence matched a translated Leishmania donovani kinetoplastid membrane protein-11 sequence, thus suggesting the use of the Leishmania sequence as a probe to select for the Trypanosoma gene. Screening of a trypanosome cosmid library with the Leishmania probe, in combination with a series of polymerase chain reaction amplifications from both genomic DNA and cDNA, allowed the determination of the entire DNA sequence and corresponding translated amino acid sequence of the trypanosome kinetoplastid membrane protein-11. The 92 amino acid sequence showed 18 percent sequence divergence from the corresponding molecule of the related kinetoplastid Leishmania donovani donovani^ including one key amino acid at position 45 which may be of functional relevance. The secondary structure of the trypanosome molecule was predicted to form two amphipathic helices connected by a random-coil segment, and suggests that it would interact with lipid bilayers in the parasite cell membrane. Northern and Southern blot analyses using the T.b. rhodesiense ViTat 1.1 clone showed that the trypanosome molecule was translated from a single transcript and that there was only a single gene copy, thus making this molecule an attractive target for knockout mutagenesis. / Graduate

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