Attenuated Salmonella VNP20009 mutant (ΔhtrA) is a promising candidate for bacteria-mediated tumour therapy in hosts with TNFR1 deficiency.

VNP20009 is attenuated Salmonella with a good safety widely used for tumour-targeting bacterial therapies. Little is known about its toxicity in hosts with low immunity. This study is the first systemically comparative analysis of their toxicity of VNP20009 and its mutant ΔhtrA in TNFR1-KO mice. Research on toxicity of tumour-targeting Salmonella in mice with immunodeficiency can facilitate the optimization of bacterial therapies with reduced adverse effects in future clinical trials.