No description available.

Live attenuated Salmonella vectors provide a unique alternative in terms of antigen presentation by acting as a vector for heterologous antigens. The efficiency of any live bacterial vector rests with its ability to present sufficient foreign antigen to the human or animal immune system to initiate the desirable protective immune response. Salmonella vectors encoding heterologous protective antigens can elicit the relevant immune responses, be it humoral, mucosal or cell-mediated. STM-1 is a Salmonella mutant developed by RMIT, harbours a mutation in the aroA gene that renders it attenuated, and is a well characterised vaccine strain currently in use to protect livestock against Salmonella infection. In previous work in this laboratory, STM1 was shown to be capable of eliciting immune responses in mice to plasmid-borne antigens. In this study STM-1 was analysed for its ability to vector the model antigen chicken ovalbumin and test antigen C. jejuni major outer membrane protein using in vivo inducible promoters such as pagC and nirB from the plasmid location. The determination of the architecture around the lesion in STM-1 also allowed the development of constructs expressing heterologous antigen from the chromosome. The induction of immune responses, both humoral and cell mediated, was analysed. Another issue addressed in this study was effect of pre-existing immune responses in the animal host against the vector or related strains and the effects on generation of immune responses against the subsequently vectored antigen. Humoral and cellular immune responses to vectored ovalbumin and C. jejuni Momp antigens were observed following vaccination with STM-1, when antigens were expressed from either the plasmid or chromosomal location. Up-regulation of immune responses, both humoral and cell mediated, was observed against the vectored antigens in animals which were pre-exposed to either the bacterial vector or related strains. These results indicate that STM-1 has the potential to be used as a vector to deliver heterologous vaccine antigens from a single copy gene in the field. Lastly, the results from this study indicate that pre-existing immune responses against the bacterial vector or a related strain do in fact enhance both humoral and T cell responses against the heterologous antigen.

<p>An analysis of the recorded cases of Salmonella in Sweden indicates that there was no significant increase between 1997-2008, including or excluding outbreaks. The most common serotypes of Salmonella in Sweden were found to be S. Typhimurium and S. Enteritidis, with only the incidence of S. Typhimurium significantly increasing between 1997-2008. The most common phage types identified were S. Typhimurium 40, 104, NST and NT, with both S. Typhimurium NST and NT found to be significantly increasing. The season that has the greatest incidence of salmonellosis is the summer, from June to August. The number of Salmonella outbreaks occurring each year was found to be statistically increasing, this was however almost certainly due to a change in cluster detection techniques introduced in 2008, since a re-analysis excluding this year found no significant increase between 1997-2007. The most common serotypes that caused outbreaks during the study period were found to be S. Typhimurium, S Enteritidis, S. Saintpaul, S. Stanley and S. Hadar. There was no relationship found between the serotypes, with the number of cases not being proportional to the number of outbreaks. Despite these positive results, it should be of concern that evidence was found indicating that the sources of Salmonella infection appear to be changing, with an increase in the presence of ‘non-domestic’ serotypes.</p><p> </p>

An analysis of the recorded cases of Salmonella in Sweden indicates that there was no significant increase between 1997-2008, including or excluding outbreaks. The most common serotypes of Salmonella in Sweden were found to be S. Typhimurium and S. Enteritidis, with only the incidence of S. Typhimurium significantly increasing between 1997-2008. The most common phage types identified were S. Typhimurium 40, 104, NST and NT, with both S. Typhimurium NST and NT found to be significantly increasing. The season that has the greatest incidence of salmonellosis is the summer, from June to August. The number of Salmonella outbreaks occurring each year was found to be statistically increasing, this was however almost certainly due to a change in cluster detection techniques introduced in 2008, since a re-analysis excluding this year found no significant increase between 1997-2007. The most common serotypes that caused outbreaks during the study period were found to be S. Typhimurium, S Enteritidis, S. Saintpaul, S. Stanley and S. Hadar. There was no relationship found between the serotypes, with the number of cases not being proportional to the number of outbreaks. Despite these positive results, it should be of concern that evidence was found indicating that the sources of Salmonella infection appear to be changing, with an increase in the presence of ‘non-domestic’ serotypes.

Zugl.: Berlin, Freie Univ., Diss., 2009

RdoA is a eukaryotic-like serine/threonine protein kinase found in Salmonella typhimurium. It is a downstream effector of the Cpx stress response pathway and has been phenotypically characterized to have a functional role in flagellin phase variation and long-term bacterial survivability. Structurally, RdoA is homologous to, choline kinase and aminoglycoside (3’) phosphotransferase IIIa (APH[3’]IIIa). These kinases all belong to a protein kinase superfamily and share highly conserved residues/motifs in their catalytic domain. In RdoA seven of these conserved amino acids were proposed to have functional roles in the phosphotransfer mechanism. Mutation of these proposed catalytic domain residues resulted in a loss of in vitro kinase activity and in vivo RdoA function for a majority of the mutants. Four of the mutants also exhibited decreased levels of stable RdoA compared to wildtype. Many protein kinases regulate activity through phosphorylation of an activation loop. Although RdoA does not contain a canonical activation loop, its carboxyl terminus is proposed to play a similar regulatory function. Mutations of a putative autophosphorylation target in the carboxyl terminus resulted in loss of in vitro kinase activity. Truncations of this region also resulted in loss of kinase activity, as well as decreasing RdoA stability. The length of the carboxyl terminus in the kinase was shown to be an important determinant in the overall structural stability of RdoA. Mutational analyses of conserved amino acid residues surrounding the putative substrate-binding cleft of RdoA revealed site specific mutants with diminished in vitro phosphorylation activity and/or RdoA levels. A subset of these mutants for which no in vitro kinase activity was detected were still able to complement RdoA function in vivo. Taken together these results indicate that this region of the protein is important for RdoA function. In summary, this work has generated a panel of RdoA mutants with several unique phenotypes that will facilitate characterization of RdoA function and of regions of the protein / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2010-09-29 21:35:42.815

No description available.

No description available.

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 121-142)

Thesis (Ph. D.)--McMaster University (Canada), 1988. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.