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A SARS‐C o V ‐2 oral vaccine development strategy based on the attenuated Salmonella type III secretion system
Author(s) -
Wu Leyang,
Li Lin,
Yin Xingpeng,
Li Chenyang,
Xin Wenjie,
Liu Lina,
Hua Zichun
Publication year - 2022
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.15720
Subject(s) - salmonella , secretion , antigen , microbiology and biotechnology , biology , virology , salmonella enterica , type three secretion system , heterologous , mutant , immunology , bacteria , gene , biochemistry , genetics
Aims This study aimed to provide a safe, stable and efficient SARS‐CoV‐2 oral vaccine development strategy based on the type III secretion system of attenuated Salmonella and a reference for the development of a SARS‐CoV‐2 vaccine. Methods and Results The attenuated Salmonella mutant Δ htrA ‐VNP was used as a vector to secrete the antigen SARS‐CoV‐2 based on the type III secretion system (T3SS). The Salmonella pathogenicity island 2 (SPI‐2)‐encoded T3SS promoter (sifB) was screened to express heterologous antigens (RBD, NTD, S2), and the SPI‐2‐encoded secretion system (sseJ) was employed to secrete this molecule (psifB‐sseJ‐antigen, abbreviated BJ‐antigen). Both immunoblotting and fluorescence microscopy revealed effective expression and secretion of the antigen into the cytosol of macrophages in vitro. The mixture of the three strains (BJ‐RBD/NTD/S2, named AisVax) elicited a marked increase in the induction of IgA or IgG S‐protein Abs after oral gavage, intraperitoneal and subcutaneous administration. Flow cytometric analysis proved that AisVax caused T‐cell activation, as shown by a significant increase in CD44 and CD69 expression. Significant production of IgA or IgG N‐protein Abs was also detected by using psifB‐sseJ‐N(FL), indicating the universality of this strategy. Conclusions Delivery of multiple SARS‐CoV‐2 antigens using the type III secretion system of attenuated Salmonella Δ htrA ‐VNP is a potential COVID‐19 vaccine strategy. Significance and Impact of the Study The attenuated Salmonella strain Δ htrA ‐VNP showed excellent performance as a vaccine vector. The Salmonella SPI‐2‐encoded T3SS showed highly efficient delivery of SARS‐COV‐2 antigens. Anti‐loss elements integrated into the plasmid stabilized the phenotype of the vaccine strain. Mixed administration of antigen‐expressing strains improved antibody induction.