Estudo do envolvimento da enzima Formil-Transferase, codificada pelo gene wbkC, na biossíntese do LPS da Brucella Abortus e avaliação da persistência e potência de uma cepa mutante para este gene em camundongos C57BL/6 e deficientes para IRF-1

• Ano de defesa: 2006
• Autor(a) principal: Thais Lourdes Santos Lacerda
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: mutante; Brucella abortus; cepa; LPS; Enzima formiltransferase; Bioquímica; Brucella
• Link de acesso: http://hdl.handle.net/1843/UCSD-8H8KWS

Brucella abortus is a Gram-negative facultative intracellular pathogen that affects several domestic animals and occasionally man, causing brucellosis. Brucella LPS is one of the main virulence factors of this bacterium. Additionally, the wbkC gene product, the focus of this study, participates in LPS biosynthesis as a formyltransferase enzyme. Alterations in wbkC may cause modifications in LPS structure altering bacterial colony morphology from smooth (S) to rough (R). The main goal of this study was to inactivate the wbkC gene of the B. abortus wild type and vaccine strains in order to generate a new vaccine strain. Mutants B. abortus wbkC S2308 and B. abortus wbkC S19 were obtained by double homologous recombination. Characterization of these mutants was performed by PCR using specific primers. Southern blot confirmed that the wild type wbkC gene was disrupted within Brucella mutants. Morphology of mutant colonies presented rough phenotype demonstrated by crystal violet staining. Immunobloting analysis of Brucella mutants was performed and their LPS were recognized by rough LPS specific monoclonal antibodies. Persistence of the mutants were studied in both murine models: IRF(-/-) and C57BL/6. Brucella wbkC mutants were shown to be less virulent than wild type and B. abortus S19 strains and similar phenotype to B. abortus RB51 strain. Regarding protective immunity, the mutant B. abortus wbkC S2308 strain was able to induce similar protection when compared to S19 and RB51 vaccine strains in IRF(-/-) mice. In conclusion, wbkC mutants were less virulent than the wild type and vaccine strains, but only B. abortus wbkC S2308 induced similar protection level as induced by the vaccine strains commercially available. This data suggests that B. abortus wbkC S2308 is a potential candidate for the development of a live vaccine against brucellosis.