Salmonella vaccine-vector study in an attenuated strain using an animal infection and cytotoxicity model with Galleria mellonella moth larvae

MARIA FLORENCIA BALLESTEROS; FABIAN E. LOPEZ; MARÍA DE LAS MERCEDES PESCARETTI; MÓNICA A. DELGADO

Salta capital

Congreso; LV ANNUAL SAIB- XIV PABMB 2019; 2019

The Salmonella RcsCDB system regulates the expression of numerous virulence genes. In previously studies, we demonstrated the virulence attenuation in Salmonella rcsC11 mutant with the constitutive activation of the RcsB regulator in an animal model. In the present study, we work with the Galleria mellonella (G. mellonella) larvae due to the great benefits that its offer as a host model including profitability, high reproducibility, ethical approval, easy handling and maintenance. The G. mellonella infection model allows the study of many stages of infection at 37 °C, the real temperature of the human body and has remarkable similarities with the vertebrate innate immune response. To this end, the infection assays have been carried out in G. mellonella larvae with the wild type 14028s Salmonella Typhimurium strain, the rcsC11 attenuated mutant, and Salmonella clinical isolates obtained from patients suffering diarrhea. In these assays, we evaluated the protective effect of rcsC11 mutant against the 14028s virulent strain. We here observed that inoculated larvae with rcsC11 were able to survive compared to the control larvae infected with the wild type strain, which died from the second day of infection. In addition, the Salmonella clinical isolates displayed an increased virulence than the 14028s laboratory strain. Even more, we show that the previously treated larvae before a second challenge with the rcsC11 attenuated strain were able to survive the re-infection with the 14028s virulent strain. This work is an adittional probe that confirms the ability of the rcsC11 mutant to serve as a candidate for an attenuated vaccine.