Immunogenicity and vaccine approach of Salmonella enterica sorovar Typhimurium flagellins.

Flagelina, a subunidade estrutural dos flagelos bacterianos, pode ser empregada em estratégias vacinais como carregadora de epitopos antigênicos fusionados ou como adjuvante. Neste trabalho avaliamos a imunogenicidade e o potencial vacinal das flagelinas Salmonella enterica sorovar Typhimurium em camundongos BALB/c após administração pelas vias oral ou intraperitoneal. Os resultados indicam que animais imunizados pela via oral com linhagens flageladas de S. Typhimurium não desenvolvem respostas de anticorpos, sistêmicos ou secretados, anti-flagelina, por outro lado, ativam respostas celulares específicas para as flagelinas em função da via de administração utilizada. Observamos ainda que as diferentes flagelinas testadas apresentam efeito adjuvante quando co-administradas pela via nasal com a fímbria CFA/I de ETEC. Em suma, os resultados apresentados contribuem para um melhor conhecimento sobre as propriedades imunológicas e adjuvantes das flagelinas de S. Typhimurium e agregam informações para o uso racional dessas proteínas em formulações vacinais.Flagellin, the structural subunit of bacterial flagella, can be used in vaccine development as a fused antigenic epitope carrier or as an adjuvant. 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. 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

Immunogenicity and vaccine approach of Salmonella enterica sorovar Typhimurium flagellins.

Flagelina, a subunidade estrutural dos flagelos bacterianos, pode ser empregada em estratégias vacinais como carregadora de epitopos antigênicos fusionados ou como adjuvante. Neste trabalho avaliamos a imunogenicidade e o potencial vacinal das flagelinas Salmonella enterica sorovar Typhimurium em camundongos BALB/c após administração pelas vias oral ou intraperitoneal. Os resultados indicam que animais imunizados pela via oral com linhagens flageladas de S. Typhimurium não desenvolvem respostas de anticorpos, sistêmicos ou secretados, anti-flagelina, por outro lado, ativam respostas celulares específicas para as flagelinas em função da via de administração utilizada. Observamos ainda que as diferentes flagelinas testadas apresentam efeito adjuvante quando co-administradas pela via nasal com a fímbria CFA/I de ETEC. Em suma, os resultados apresentados contribuem para um melhor conhecimento sobre as propriedades imunológicas e adjuvantes das flagelinas de S. Typhimurium e agregam informações para o uso racional dessas proteínas em formulações vacinais.Flagellin, the structural subunit of bacterial flagella, can be used in vaccine development as a fused antigenic epitope carrier or as an adjuvant. 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. 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

A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature.

Sensing and responding to environmental signals is critical for bacterial pathogens to successfully infect and persist within hosts. Many bacterial pathogens sense temperature as an indication they have entered a new host and must alter their virulence factor expression to evade immune detection. Using secondary structure prediction, we identified an RNA thermosensor (RNAT) in the 5' untranslated region (UTR) of tviA encoded by the typhoid fever-causing bacterium Salmonella enterica serovar Typhi (S. Typhi). Importantly, tviA is a transcriptional regulator of the critical virulence factors Vi capsule, flagellin, and type III secretion system-1 expression. By introducing point mutations to alter the mRNA secondary structure, we demonstrate that the 5' UTR of tviA contains a functional RNAT using in vitro expression, structure probing, and ribosome binding methods. Mutational inhibition of the RNAT in S. Typhi causes aberrant virulence factor expression, leading to enhanced innate immune responses during infection. In conclusion, we show that S. Typhi regulates virulence factor expression through an RNAT in the 5' UTR of tviA. Our findings demonstrate that limiting inflammation through RNAT-dependent regulation in response to host body temperature is important for S. Typhi's "stealthy" pathogenesis