Abstract
Live Salmonella vaccine vectors offer a remarkable platform for delivering immunogens and therapeutic molecules by mimicking natural intracellular infections; however, pre-existing anti-vector immunity can impede effective deployment. Measures to alleviate pre-existing immunity include the use of heterologous vectors, development of highly attenuated strain enabling greater payload, removal of major immunoreactive components from the vector, and/or augmentation of delivered antigens via increased presentation in antigen presenting cells. Here we report a Salmonella Typhimurium (ST) vector-JOL1800 that embodies these requisite properties. JOL1800 is a highly attenuated, auxotrophic, and O-antigen deficient rough-mutant strain. Heterologous bacterial and viral antigens were expressed and delivered using JOL1800 in mice, irrespective of the inoculation route successful inductions of the mucosal and systemic humoral responses were observed. Compared to smooth LPS vector delivery, we observed an increased fraction of delivered-antigen presenting dendritic cells and a higher frequency of delivered-antigen displayed per macrophage. Upon post-priming with JOL1800 delivery, efficacy of the delivery was minimally affected as indicated by insignificant decrease in colonization, humoral and cellular responses. Our results show that the generated vector is capable of remote antigen delivery, manifests higher antigen presentation, is Differentiating Infected from Vaccinated Animals (DIVA) capable, evades normal pre-existing immunity, and can be deployed for effective delivery.
Highlights
Salmonella enterica serovar Typhimurium (ST) is a gram-negative intracellular pathogen and is one of the most extensively studied organisms in the areas of basic science research, systemic bacterial infections, immunological profiling, and host resistance to pathogens
Our results show that the generated vector is capable of remote antigen delivery, manifests higher antigen presentation, is Differentiating Infected from Vaccinated Animals (DIVA) capable, evades normal pre-existing immunity, and can be deployed for effective delivery
The present study reported the generation of a suitable bacterial vector for the use in vaccine antigen delivery
Summary
Salmonella enterica serovar Typhimurium (ST) is a gram-negative intracellular pathogen and is one of the most extensively studied organisms in the areas of basic science research, systemic bacterial infections, immunological profiling, and host resistance to pathogens. It is widely studied for its use as a vaccine and live vector vaccine and as an anti-tumor vector due to its intrinsic properties [1, 2]. The intracellular localization of ST allows for the cytosolic delivery of drugs and cytotoxic proteins that are otherwise unable to enter eukaryotic cells. A live ST vector that constitutively expresses beneficial proteins would deliver the antigen to various tissues of the host including systemic as well as mucosal sites
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