Call number: LD2668 .T4 1962 T73

BACKGROUND:Bovine tuberculosis (TB) caused by Mycobacterium bovis is primarily a disease of ruminants, particularly cattle (Bos primigenius) and buffalo (Syncerus caffer), and is endemic in most developing countries. To date, studies done in Uganda have documented the prevalence of M. bovis in cattle, humans and wild life, in addition to non-tuberculous mycobacteria in pigs. Pigs are increasingly becoming an important component of the livestock sector and share the human ecosystem in rural Uganda. It is therefore of public health interest that they are not a source of human infections. As a follow up to previously published findings on mycobacteria in pigs, this study was aimed at investigating the occurrence and molecular characteristics of M. bovis detected in slaughter pigs in Mubende district, Uganda. One hundred fifty mesenteric lymph nodes with lesions suggestive of mycobacterial infections were collected from approximately one thousand slaughtered pigs in Mubende district over a period of five months. The isolation and identification of M. bovis was done using conventional mycobacteriological methods. Mycobacteria belonging to the Mycobacterium tuberculosis complex (MTC) were identified to species level using deletion analysis. Molecular typing was done using Spoligotyping and MIRU-VNTR analysis. Molecular data were analysed and interpreted using MIRU-VNTR plus, SpolDB4.0 and the Mycobacterium bovis spoligo database.RESULTS:Of the examined animals, one boar and two sows from Madudu Sub County were infected with M. bovis which presented as lesions of a deep yellow colour and a grit-like texture in the mesenteric lymph nodes. This represents 2% (3/150) of the lymph nodes where lesions suggestive of mycobacterial infections were detected. Molecular analysis revealed that the isolates from the infected pigs showed identical MIRU-VNTR profile and spoligotype (SB1469).CONCLUSIONS:This is the first study documenting the occurrence of M. bovis in slaughter pigs in Uganda, revealing that one in fifty slaughter pigs with suspected lesions in mesenteric lymph nodes were infected. Molecular analysis revealed that the isolates were identical, showing a spoligotype previously reported from humans and cattle in the north eastern part of the Uganda cattle corridor. This finding is of public health importance, therefore there is a need for close cooperation between medical and veterinary professionals in designing and implementing control and prevention measures that safeguard the public from this potential source of zoonotic TB in Uganda.

Biodegradable wastes cause high emissions of greenhouse gases (GHG) if not properly treated. The emissions can be reduced by the development of an effective waste management strategy. Waste-to-energy technologies, such as anaerobic digestion (AD) can be utilised for this purpose. Biomass energy from wastes is of particular interest to Cyprus that has to meet legal commitments for reducing its GHG emissions by 5% compared to 2005 levels and increase the contribution of renewable energy sources to 13% by 2020. This research project is making a significant contribution to this effort. The research considered the quantities and distribution of biodegradable waste in Cyprus and developed the necessary methodologies and tools for their estimation and determination of the potential for energy production through AD. The study identified that the predominant biodegradable wastes in Cyprus are the biodegradable fraction of municipal solid waste (MSW), sewage sludge, solid and liquid agricultural residues and solid and liquid wastes from the food and drinks industries. According to the estimated amount of solid and liquid biomass from these waste streams, at least 4,200 TJ of energy can be produced through AD, which represents 4% of the national energy demand. Livestock production is a very important source of waste due to the high potential of biogas production with the aid of AD. The produced energy can satisfy the needs of a farm, reduce the consumption of fuel and provide renewable energy to the national grid. Simple methodologies were developed and implemented for the estimation of energy consumption of the farm and the respective GHG emissions. It was found that in Cyprus the annual energy consumption per animal is lower than most other countries, due to favourable weather conditions which reduce the energy needs for heating. The emissions from energy use in livestock production contribute 16% to the total agricultural energy emissions. Literature review on AD, confirmed the complexity of the process, due to the many microorganisms involved. To estimate the potential of biogas production from animal waste through AD, three methods were developed based on the accepted relations that exist between Chemical Oxygen Demand (COD), volatile solids (VS), waste digested and biogas production. The results show that livestock production could cover the complete agricultural energy demand and make a considerable contribution to the renewable energy targets of Cyprus. Due to the identified importance that AD could have for Cyprus and to overcome deficiencies of existing models, the software FARMS was developed. The tool can be used by any farmer, consultant or policy maker for the estimation of the potential of biogas production, associated costs, reduction in GHG emissions and comparison of scenarios for waste management. Furthermore, the validation of the tool is presented. This was done through comparison against data collected from existing AD plants and through testing by potential users.

The protozoan parasite Toxoplasma gondii (T. gondii) is an important zoonotic pathogen, which has the ability to infect all warm blooded mammals including humans, with approximately one third of the human population predicted to be infected. Transmission of the parasite to the foetus during pregnancy can result in miscarriage, however, a child infected during pregnancy may go on to develop clinical symptoms such as retinochoroiditis (ocular toxoplasmosis), hydrocephalus or learning difficulties in later life. Post-natally acquired infection in humans is generally asymptomatic, however, individuals who are immunocompromised may develop ocular toxoplasmosis or toxoplasmic encephalitis. T. gondii type II is reported to be the predominant genotype in Europe and the United States, but currently very little information exists about the prevalence and genotypes present within Great Britain. Consumption of T. gondii tissue cysts from raw or undercooked meat is a main source of infection for humans, with infected pork being considered a high risk. Currently the “gold standard” for assessing the viability of infective T. gondii tissue cysts is by an in vivo mouse bioassay. However, more recent ethical requirements to reduce, refine or replace experimental animals raises the question as to whether molecular technologies could be incorporated into these studies to reduce mouse numbers. The main aims of this PhD were to: (i) determine the prevalence and genotypes of T. gondii within different wildlife populations and humans in Great Britain; (ii) determine whether vaccination of pigs with a live attenuated strain of T. gondii would reduce the load of viable T. gondii tissue cysts within this species; (iii) study the viability and dissemination of tissue cysts from oocyst and bradyzoite infected pigs and (iv) to compare mouse bioassay with molecular detection of T. gondii DNA from experimentally infected pigs. The main findings of this work show that the prevalence of T. gondii within carnivorous wildlife varied from 6.0% to 44.4% depending on the host species with type II being the predominant lineage identified, however, type III and two alleles for type I were also present. In humans, serological detection of the parasite from a group of Scottish blood donors from Glasgow and Dundee (n=1403) was determined at 13.0%, molecular detection of T. gondii in human brains (n=151) from the Sudden Death Brain Bank show a prevalence of 17.9%. A correlation between increasing age and an increase in the detection of parasite was identified from both study groups. T. gondii strain genotyping using DNA extracted from human brains identified alleles for type I and III, however, no direct link between cause of death and detection of parasite DNA could be made. Live vaccination and subsequent oocyst challenge of pigs showed a significant reduction in the establishment of viable T. gondii tissue cysts. Mouse bioassay clearly demonstrates this result, where 100% of mice that were inoculated with homogenised tissues from vaccinated/challenged pigs survived, compared to the survival of only 51% of mice, which received homogenised tissues from non-vaccinated/oocyst challenged animals. In addition, porcine tissues from pigs challenged with either oocysts or bradyzoites did not show a significant difference in mouse survival following bioassay of these tissues. Challenge with either stage of the parasite (oocysts or bradyzoites) showed a preference to form tissue cysts in brains and highly vascular muscles (tongue, diaphragm, heart or masseter) of pigs. The findings, comparing mouse bioassay with molecular detection of parasite DNA from homogenised porcine tissue (prior to inoculation into mice), showed similar levels of detection. However, mouse bioassay was more sensitive and also provides evidence of parasite viability. In conclusion, this research not only provides current figures for prevalence and genotypes of T. gondii in both wildlife and humans in Great Britain, it also successfully answers the question as to whether live vaccination of pigs with the S48 strain can reduce the tissue cyst burden. These promising results show the potential of a vaccine against T. gondii in producing safer pork for human consumption. Although the mouse bioassay still remains the most sensitive method for the detection and viability assessment of tissue cysts, further research should be carried out in this area, perhaps incorporating a technique such as magnetic capture qPCR, to enable an effective in vitro technique to be developed.

published_or_final_version / Computer Science / Master / Master of Philosophy

The specificity of guinea pig liver transglutamlnase was Investigated by the determination of modification sites within polypeptides and proteins of known sequence and (In some cases) folded structure. It was shown that some globular proteins have substrate properties for transglutamlnase In conformations which resemble their native states. Novel substrate sites for transglutamlnase were determined within the following proteins: 1) bovine B-Iactoglobulln. 2) the Hls3~ Gln388 mutant form of yeast phosphoglycerate kinase. 3) bovine B-caseln. 4) porcine pepsin. Despite the high exposure of many glutamlnyl residues within these proteins only a small fraction of these residues were observed to be reactive towards transglutamlnase. This Is taken to Indicate that features such as the chemical nature of the amino acid side chains In the local vicinity of unreactive glutamlnyl residues strongly determine the specificity of transglutamlnase. When structural models were available for substrates of transglutamlnase, the local secondary structure associated with substrate sites could be assessed. When no such models were available computer based methods were used to predict the local secondary structures associated with these sites. This approach allows substrate sites to be classified according to their local conformational preference Into conformationally flexl ble (type A substrates) and more conformationally restricted (type B substrates). Since diverse amino acid sequences are observed to surround the reactive glutamlnyl residues of many of the non-physiological substrates of transglutamlnase, It was assumed that the glutamlnyl residues within these sequences were probably reactive due to having; 1) a favourable stereochemistry during modification by transglutaminase 2) a lack of Inhibitory features. In order to determine why some exposed glutamlnyl residues were reactive and others not, It was necessary to find features which were present In unreactive sequences but absent In reactive ones. Through the use of this approach an "anti-consensus sequence" motif was Identified. This was based on the observation that exposed glutamlnyl residues which were unreactive towards transglutamlnase often have charged residues within their surrounding sequences. The distribution of allowed/disallowed residues within substrate sequences, together with what Is known concerning the conformational preference of transglutamlnase for its substrates was built Into a preliminary set of "rules'·. These rules may provide a basis for understanding the observed specificity of transglutamlnase. The application of these rules to a number of model systems has resulted In the correct prediction of both reactive and unreactive glutamlnyl side chains within a number of proteins. The demonstration of the substrate properties of the Hls3~ln388 mutant of phosphoglycerate kinase Illustrates the feasibility of Introducing a novel substrate site for transglutamlnase Into a protein using recombinant DNA technology.

Clostridium difficile and Clostridium perfringens are among the most commonagents of enteric disease in both humans and domestic animals. The former continues to increase in prevalence and diseases caused by the latter persist. Infection with a recently emergedhypervirulent strain (NAP1/027/III) of C. difficile is increasingly common andserious sequelae and fatalities are much more common in these patients. In neonatalpiglets, C. difficile infection (CDI) has become a common occurrence. Historically,isolation of C. perfringens type A from patients with enteric disease has been consideredinconsequential due to its presence in the normal intestine and to the mild nature ofdisease syndromes such as porcine enteritis. However, both CDI and type A diseasecause losses to the swine industry and pigs have been implicated as a possible source ofC. difficile for infection in humans. We investigated the epidemiology and pathogenesisof porcine CDI, and immunity against porcine CDI and type A enteritis. The occurrenceof CDI in integrated swine production facilities was most common in neonatal pigs.Infection in sows was rare, and finisher pigs were culture negative. All C. difficile strainswere ribotype 078. Hypervirulent strain NAP1/027/TTIII was more virulent in neonatalpigs than both a historic human historic human strain and a porcine strain with toxinproducing potential similar to ribotype 027 strains. Inoculation of anti-microbial-treatedadolescent pigs with NAP1/027/III did not cause disease. Ingra-gastric inoculation ofpigs with purified TcdA resulted in severe small intestine damage which isuncharacteristic of natural disease; effects of TcdB were minimal. Passive immunizationof piglets against C. difficile TcdA or C. perfringens type A alpha (CPA) and beta 2(CPB2) toxins did not prevent disease.

No description available.

This study is concerned with a critical comparison of the passive transfer mechanisms of tuberculin and chemical contact hypersensitivities in the guinea pig by use of a four phase experimental approach.

Call number: LD2668 .T4 1950 W3 / Master of Science