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Overexpression of T3SS translocation signals in Salmonella causes delayed attenuation.

ABSTRACT: Engineering pathogens is a useful method for discovering new details of microbial pathogenesis and host defense. However, engineering can result in off-target effects. We previously engineered Salmonella enterica serovar Typhimurium to overexpress the secretion signal of the type 3 secretion system effector SspH1 fused with domains of other proteins as cargo. Such engineering had no virulence cost to the bacteria for the first 48 hours post infection in mice. Here, we show that after 48 hours, the engineered bacteria manifest an attenuation that correlates with the quantity of the SspH1 translocation signal expressed. In IFN-γ-deficient mice, this attenuation was weakened. Conversely, the attenuation was accelerated in the context of a pre-existing infection. We speculate that inflammatory signals change aspects of the target cell's physiology, which makes host cells less permissive to S. Typhimurium infection. This increased degree of difficulty requires the bacteria to utilize its T3SS at peak efficiency, which can be disrupted by engineered effectors.

SUBMITTER: Abele TJ

PROVIDER: S-EPMC10790824 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature

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Overexpression of T3SS translocation signals in <i>Salmonella</i> causes delayed attenuation.

Abele Taylor J TJ Billman Zachary P ZP Harvest Carissa K CK Bryan Alexia K AK Larson Heather N HN Coers Jörn J Miao Edward A EA

Infection and immunity 20231212 1

Engineering pathogens is a useful method for discovering new details of microbial pathogenesis and host defense. However, engineering can result in off-target effects. We previously engineered <i>Salmonella enterica</i> serovar Typhimurium to overexpress the secretion signal of the type 3 secretion system effector SspH1 fused with domains of other proteins as cargo. Such engineering had no virulence cost to the bacteria for the first 48 hours post infection in mice. Here, we show that after 48 h ...[more]

PMID: 38084951

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Project description:BackgroundSalmonella enterica species are enteric pathogens that cause severe diseases ranging from self-limiting gastroenteritis to enteric fever and sepsis in humans. These infectious diseases are still the major cause of morbidity and mortality in low-income countries, especially in children younger than 5 years and immunocompromised adults. Vaccines targeting typhoidal diseases are already marketed, but none protect against non-typhoidal Salmonella. The existence of multiple non-typhoidal Salmonella serotypes as well as emerging antibiotic resistance highlight the need for development of a broad-spectrum protective vaccine. All Salmonella spp. utilize two type III Secretion Systems (T3SS 1 and 2) to initiate infection, allow replication in phagocytic cells and induce systemic disease. T3SS-1, which is essential to invade epithelial cells and cross the barrier, forms an extracellular needle and syringe necessary to inject effector proteins into the host cell. PrgI and SipD form, respectively, the T3SS-1 needle and the tip complex at the top of the needle. Because they are common and highly conserved in all virulent Salmonella spp., they might be ideal candidate antigens for a subunit-based, broad-spectrum vaccine.Principal findingsWe investigated the immunogenicity and protective efficacy of PrgI and SipD administered by subcutaneous, intranasal and oral routes, alone or combined, in a mouse model of Salmonella intestinal challenge. Robust IgG (in all immunization routes) and IgA (in intranasal and oral immunization routes) antibody responses were induced against both proteins, particularly SipD. Mice orally immunized with SipD alone or SipD combined with PrgI were protected against lethal intestinal challenge with Salmonella Typhimurium (100 Lethal Dose 50%) depending on antigen, route and adjuvant.Conclusions and significanceSalmonella T3SS SipD is a promising antigen for the development of a protective Salmonella vaccine, and could be developed for vaccination in tropical endemic areas to control infant mortality.

Dataset Information

Overexpression of T3SS translocation signals in Salmonella causes delayed attenuation.

Publications

Overexpression of T3SS translocation signals in <i>Salmonella</i> causes delayed attenuation.

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