http://hdl.handle.net/10033/6889 Sun, 19 May 2013 12:59:07 GMT 2013-05-19T12:59:07Z http://hdl.handle.net/10033/283779 Title: Development and characterization of attenuated metabolic mutants of Bordetella bronchiseptica for applications in vaccinology. Authors: Yevsa, Tetyana; Ebensen, Thomas; Fuchs, Barbara; Zygmunt, Beata; Libanova, Rimma; Gross, Roy; Schulze, Kai; Guzmán, Carlos A Abstract: Bordetella bronchiseptica is an important pathogen causing a number of veterinary respiratory syndromes in agriculturally important and food-producing confinement-reared animals, resulting in great economic losses annually amounting to billions of euros worldwide. Currently available live vaccines are incompletely satisfactory in terms of efficacy and safety. An efficient vaccine for livestock animals would allow reducing the application of antibiotics, thereby preventing the massive release of pharmaceuticals into the environment. Here, we describe two new potential vaccine strains based on the BB7865 strain. Two independent attenuating mutations were incorporated by homologous recombination in order to make negligible the risk of recombination and subsequent reversion to the virulent phenotype. The mutations are critical for bacterial metabolism, resistance to oxidative stress, intracellular survival and in vivo persistence. The resulting double mutants BB7865 risA aroA and BB7865 risA dapE were characterized as promising vaccine candidates, which are able to confer protection against colonization of the lower respiratory tract after sublethal challenge with the wild-type strain. Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10033/283779 2013-01-01T00:00:00Z http://hdl.handle.net/10033/255243 Title: Vaccines: from empirical development to rational design. Authors: Rueckert, Christine; Guzmán, Carlos A Abstract: Infectious diseases are responsible for an overwhelming number of deaths worldwide and their clinical management is often hampered by the emergence of multi-drug-resistant strains. Therefore, prevention through vaccination currently represents the best course of action to combat them. However, immune escape and evasion by pathogens often render vaccine development difficult. Furthermore, most currently available vaccines were empirically designed. In this review, we discuss why rational design of vaccines is not only desirable but also necessary. We introduce recent developments towards specifically tailored antigens, adjuvants, and delivery systems, and discuss the methodological gaps and lack of knowledge still hampering true rational vaccine design. Finally, we address the potential and limitations of different strategies and technologies for advancing vaccine development. Thu, 01 Nov 2012 00:00:00 GMT http://hdl.handle.net/10033/255243 2012-11-01T00:00:00Z http://hdl.handle.net/10033/254172 Title: NKT cell stimulation with α-galactosylceramide results in a block of Th17 differentiation after intranasal immunization in mice. Authors: Zygmunt, Beata M; Weissmann, Sebastian F; Guzman, Carlos A Abstract: In a previous study we demonstrated that intranasal (i.n.) vaccination promotes a Th17 biased immune response. Here, we show that co-administration of a pegylated derivative of α-galactosylceramide (αGCPEG) with an antigen, even in the presence of Th17-polarizing compounds, results in a strong blocking of Th17 differentiation. Additional studies demonstrated that this phenomenon is specifically dependent on soluble factors, like IL-4 and IFNγ, which are produced by NKT cells. Even NK1.1 negative NKT cells, which by themselves produce IL-17A, are able to block Th17 differentiation. It follows that the use of αGCPEG as adjuvant would enable to tailor Th17 responses, according to the specific clinical needs. This knowledge expands our understanding of the role played by NKT cells in overall control of the cytokine microenvironment, as well as in the overall shaping of adaptive immune responses. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10033/254172 2012-01-01T00:00:00Z http://hdl.handle.net/10033/245231 Title: Microevolution of pandemic Vibrio parahaemolyticus assessed by the number of repeat units in short sequence tandem repeat regions. Authors: García, Katherine; Gavilán, Ronnie G; Höfle, Manfred G; Martínez-Urtaza, Jaime; Espejo, Romilio T Abstract: The emergence of the pandemic strain Vibrio parahaemolyticus O3:K6 in 1996 caused a large increase of diarrhea outbreaks related to seafood consumption in Southeast Asia, and later worldwide. Isolates of this strain constitutes a clonal complex, and their effectual differentiation is possible by comparison of their variable number tandem repeats (VNTRs). The differentiation of the isolates by the differences in VNTRs will allow inferring the population dynamics and microevolution of this strain but this requires knowing the rate and mechanism of VNTRs' variation. Our study of mutants obtained after serial cultivation of clones showed that mutation rates of the six VNTRs examined are on the order of 10(-4) mutant per generation and that difference increases by stepwise addition of single mutations. The single stepwise mutation (SSM) was deduced because mutants with 1, 2, 3, or more repeat unit deletions or insertions follow a geometric distribution. Plausible phylogenetic trees are obtained when, according to SSM, the genetic distance between clusters with different number of repeats is assessed by the absolute differences in repeats. Using this approach, mutants originated from different isolates of pandemic V. parahaemolyticus after serial cultivation are clustered with their parental isolates. Additionally, isolates of pandemic V. parahaemolyticus from Southeast Asia, Tokyo, and northern and southern Chile are clustered according their geographical origin. The deepest split in these four populations is observed between the Tokyo and southern Chile populations. We conclude that proper phylogenetic relations and successful tracing of pandemic V. parahaemolyticus requires measuring the differences between isolates by the absolute number of repeats in the VNTRs considered. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10033/245231 2012-01-01T00:00:00Z