| Congresso Brasileiro de Microbiologia 2023 | Resumo: 654-1 | ||||
Resumo:The Galleria mellonella, a wax moth is a recent animal model for in vivo infection widely used in the larvae stage, because of its similarities to human immune defenses. The larvae immune system comprise cells called hemocytes resembling blood cells defenses from mammals, and also a chemical response to infections. These characteristics promote insights into bacterial pathogenesis. Salmonella enterica Typhimurium is an enteropathogenic bacterium responsible for countless deaths and a major concern for public health services due to its ability to cause gastroenteritis and septicemia. The primary reservoirs of the bacterium are chickens, porcine, and cattle, and their transmission to humans occurs through contaminated food and water. This concern led to several studies to develop an oral vaccine using attenuated mutants of Salmonella. Previously, several Salmonella enterica mutants strains were constructed, evaluated, and described in other infection models in the literature. Therefore, we aimed to test G. mellonella as a model for the characterization of known vaccine-candidate mutant strains regarding virulence attenuation, validating it as a model for the initial characterization of attenuated strains. The results demonstrate that G. mellonella is an effective model for analyzing virulence attenuation in the mutant strains ΔcyaΔcrp, ΔcyaΔcrpΔasd, ΔaroA, and ΔaroAΔasd, since the percentage of survival was higher in larvae inoculated with mutants strains when compared to the wild-type (WT) strains. In addition, using the colony-forming unit (CFU) count we observed that mutant strains were less able to multiply and survive inside larvae. Furthermore, we did a hemocyte count for ΔaroA and ΔaroAΔasd and WT strain We observed a lower hemocyte level in larvae inoculated with the WT strains, which correlated to higher multiplication and survival of bacteria inside the larvae. In the histological analysis using the hematoxylin and eosin staining, we observed intense tissue damage in the larvae infected with the WT compared to larvae inoculated with ΔaroA and ΔaroAΔasd, reinforcing the attenuation of virulence of these strains. Therefore, this infection model is effective as an initial screening, besides is cheaper and faster compared to the mammals model, to verify the attenuation of the virulence of Salmonella Typhimurium strains with vaccine potential. Palavras-chave: attenuation, Galleria mellonella, infection model, Salmonella Typhimurium , vaccines Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) | |||||