Babesia bovis is a causative agent of bovine babesiosis and is transmitted by vector ticks, Rhipicephalus (Boophilus) spp. The disease has a high mortality rate in susceptible cattle, causing serious economic loss. At present, the only commercial vaccine is culture-based with limited availability. No effective molecular vaccine has been developed to date. Generating a vaccine with specific critical epitopes responsible for protection against B. bovis is critically important. Immunity against B. bovis requires both innate and adaptive responses, with antigen-specific CD4+ T cells essential to the latter through production of IFN-γ. Fourteen B. bovis proteins were selected as putative vaccine candidates and their full-length genes cloned for recombinant protein production intended for evaluating peripheral blood mononuclear cell IFN-γ secretion level from experimentally infected animals in ELISPOT. All proteins expressed in insoluble form (inclusion bodies) and could not be purified. B. bovis genes were then truncated to exclude signal peptide and transmembrane regions, then cloned and expressed using pET101/D-TOPO in Escherichia coli to obtain soluble, useable proteins. Only recombinant B. bovis MSA1, MSA2b and MSA2a1 proteins were successfully expressed in soluble form. These proteins induce invasion-blocking antibodies in immunized cattle, are hypothesized to elicit protection in susceptible animals, but were previously studied by others. Due to failure to produce new candidates to assay, the animal experiments were not performed. Instead, sera from field-infected cattle were assayed for reactivity against the MSA proteins by indirect immunofluorescent antibody (IFA) and western blot (WB) analysis. Field sera from South Texas (#41) and the Mexican Yucatan (#6, #9 and #11) along with positive and negative controls were tested. In IFA test, cattle #6, #9 and #41 were positive while #11 was negative. In WB, #41 and #6 reacted with the recombinant MSA proteins and with control B. bovis whole parasite lysate. However, both #11 and #9 had no signal in WB, although the latter was positive in IFA. Several theories may explain this phenomenon, such as the different preparation process of the antigen in the two tests, strain differences between sera and test antigens, or the different design and nature of each test.

NADPH: cytochrome P450 oxidoreductase (POR) is an enzyme that is able to catalyze transfer of electrons from NADPH, via two-flavin cofactors, to various redox partners. Therefore, POR is essential for multiple metabolic processes, including reactions catalyzed by cytochromes P450. Due to all microsomal P450s depending on POR for the supply of electrons, disruption of POR may affect all microsomal P450 enzyme activities. Polymorphisms in human POR have been shown to lead to development phenotypes, the severity of which differs significantly depending on the degree of POR impairment. This thesis is focused on the preparation of POR, which is similar to combinatorial allele carrying two single nucleotide polymorphisms P228L and A503V, functionally not clearly characterized at that time. However, disastrous consequences have currently not been noted. Moreover, the presence of A503V has been confirmed as the most common allele, but there is evidence that A503V influences the activity of some redox partners. In present thesis there were two genes subcloned into expression plasmids pCW. The first of which carries the cDNA encoding the POR and the other carrying cDNA encoding POR with the histidine-tag. Expression of the recombinant POR was carried out in the heterologous bacterial system, using...

The bacterium Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infection worldwide. When left untreated, chlamydial infections can lead to severe complications, such as infertility. Lack in current prevention and management due to its asymptomatic course of infection highlight the need for an effective vaccine against chlamydia. There is no vaccine at present to protect against chlamydia, but research is ongoing. A research group at Örebro University has developed a protein antigen candidate. This project focused on the production of the candidate, here called Protein X, for preclinical trials. This included optimising production in Escherichia coli to maximise formation of soluble protein, optimising purification, buffer exchange and removal of His-tag. It was found that formation of soluble protein was favoured in lower expression temperatures. Furthermore, purification was performed on soluble and insoluble protein fractions using immobilised metal affinity chromatography. However, issues with inefficient binding to the resin and purity could not be solved and further optimisation is needed. Buffers were tested to find a suitable buffer for preclinical experiments, but the protein precipitated in all buffers. It was however found that protein from the insoluble fraction dissolved in pure water. Lastly, removal of the His-tag was performed with a non-enzymatic method that utilises nickel ions instead of expensive proteases. Efficient removal was however not achieved and enzymatic methods may be considered instead. In conclusion, this project highlighted issues in the production of Protein X and may guide the research group towards improving this process for efficient preclinical preparations.