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Massis LM. Immunogenicity and vaccine approach of Salmonella enterica sorovar Typhimurium flagellins. [Ph. D. Thesis]. Sao Paulo: Instituto de Ciencias Biomedicas da Universidade de Sao Paulo; 2007. Flagellin, the structural subunit of bacterial flagella, can be used in vaccine development as a fused antigenic epitope carrier or as an adjuvant. It can either be co-administrated through mucosal or parenteral route. These features regard flagellin properties which activate response mechanisms of both innate and acquired immunological systems. Salmonella enterica strains express many different flagellar types. Among these, strains belonging to serovar Typhimuirum express two flagellar types: FliCi (phase 1), coded by fliCi gene, and FljB (phase 2), coded by fljB gene. In this work we evaluated the immunogenicity and vaccine approach of S. Typhimurium flagellin in BALB/c mice after administration by oral or intraperitoneal route. Vaccine strains derivatives from S. Typhimurium SL3261 aroA were genetically modified to express only one flagellar type, which enabled us to evaluate specific anti-flagellin responses in mice, including serum (IgG) and secreted (IgA) antibody response and also cellular response (T CD4 e TCD8). In addition, the adjuvant approach of flagellin after co-administration with CFA/I fimbriae (expressed by Escherichia coli enterotoxigenic strains (ETEC)) by nasal route was also accessed. Our results indicate that mice immunized by oral route with flagellated S. Typhimurium strains do not develop any anti-flagellin antibody response, be it serum or secreted. On the other hand, specific anti-flagellin cellular response was observed depending on the chosen route of immunization with S. Typhimurium attenuated strain. Furthermore, all flagellins tested proved to be efficient adjuvants when co-administrated with CFA/I fimbriae by nasal route. Together, these results contribute to a better understanding of the immunological and adjuvant properties of S. Typhimurium flagellins and also provide information on the rational use of these proteins in vaccine development.

Com o objetivo de identificar a patogenicidade e resistência a antimicrobianos da cepa de E. coli BK99, foram utilizados alguns testes: aglutinação em lâmina para detecção da fímbria F5, produção de STa, ensaios para hemolisinas e colicinas, patogenicidade em leitões e antibiograma. A cepa BK99 apresentou o seguinte perfil: F1+, F5+, STa+, Col V+, Hly-, ST R, KA R, NO R, TT R SF R e foi capaz de provocar a doença clínica e morte em leitões inoculados; também foi possível o resgate dessa cepa de fezes diarréicas e do conteúdo intestinal dos leitões revelando, assim, alto índice de recuperação de colônias portadoras da fímbria F5+. Os resultados permitem concluir que a cepa de E. coli BK99 é produtora de fatores de virulência e reproduz experimentalmente a colibacilose suína neonatal. In order to evaluate the pathogenicity and antimicrobial resistance pattern of BK99 E. coli strain, several tests were assessed: slide agglutination for detection of the fimbriae F5, STa production, hemolytic and colicin activity, pathogenicity assessement using piglet inoculation and antimicrobial resistance to drugs. The strain BK99 showed the following profile: F1+, F5+, STa+, Col V+, Hly-, ST R, KA R, NO R, TT R SF R. It produced clinical disease and death of infected piglets. Moreover, it was possible to recover the BK99 strain from diarrheic feces and from the gut contents of the piglet, with high rate of recovery of colonies expressing fimbriae F5+. The present results suggest that the E. coli BK99 strain could produce virulence factors and experimentally reproduce neonatal colibacillosis in pigs.