Simultaneous oral immunization of mice with live attenuated Escherichia coli expressing LT192-STa13 and LT192-STb fusion immunogen, respectively, for polyvalent vaccine candidate

Abstract

Previous epidemiological study showed that most of the porcine enterotoxin Escherichia coli (ETEC) strains harbor multiple enterotoxins but lack any of the fimbriae or non-fimbrial adhesion genes. Therefore, effective ETEC vaccines need to aim directly at all the enterotoxin antigens. The objective of this study was to evaluate the simultaneous immune effect of two live attenuated E. coli strains expressing LTR192G-STaA13Q and LTR192G-STb fusion immunogen, respectively. The results showed that both local mucosal and systemic immune responses against LT, STa, STb, and F41 were induced in BALB/c mice immunized orally with the recombinant E. coli strains ER-A and ER-B simultaneously. In addition, results of cellular immune responses showed that stimulation index (SI) values of immunized mice were significantly higher than control mice (P < 0.05) and a marked shift toward type-2 helper T lymphocyte (Th 2) immunity. Moreover, the induced antibodies demonstrated neutralizing effects on LT, STa, and STb producing E. coli infection. These data indicated that the use of recombinant E. coli ER-A and ER-B could be a valuable strategy for future polyvalent vaccine development of ETEC.

Targeting peptide‐enhanced antibody and CD11c+dendritic cells to inclusion bodies expressing protective antigen against ETEC in mice

“…The production of the IgG2a antibody accompanied the development of IgM and IgA (35,36). The production of specific IgA and IgG against fimbriae (F41) and enterotoxins (LT and STa) was with neutralizing activity through the oral immunization in BALB/c mice (37,38). The specific IgA produced was much more effective in neutralizing the fimbriae and enterotoxins, which in turn, would neutralize the ETEC entering the small intestine.…”

Expression fusion immunogen by live attenuated Escherichia coli against enterotoxins infection in mice

“…V00612.1) and Strain LT 192 ‐STb (GenBank accession no. ) have been previously described (Liu et al ., ,). The plasmids constructed and used are listed in Table .…”

Genetic editing of the virulence gene of Escherichia coli using the CRISPR system

“…E. coli Trans1-T1 was used as a cloning host. The ETEC strains of E. coli O141:K85, E. coli O142 and E. (Liu et al, 2015) E. coli O142 estA This laboratory (Yuan et al, 2014) pMD19T coli DN1502 were used in the genome engineering after the susceptibility test, especially kanamycin and spectinomycin. E. coli O141:K85 (CVCC197) was a porcine ETEC fieldisolated strain deposited in the Chinese Veterinary Culture Collection Center.…”

“…E. coli O141:K85 (CVCC197) was a porcine ETEC fieldisolated strain deposited in the Chinese Veterinary Culture Collection Center. E. coli O142 and E. coli DN1502 were isolated from diarrhea claves, and their virulence were tested in our laboratory (Liu et al, 2015;Yuan et al, 2014). Y-1 mouse adrenocortical cells were purchased from Shanghai Cell Bank, Chinese Academy of Sciences.…”

“…ETEC affects intestinal immunity through NF-κB and MAPK signaling pathways (Yang et al, 2016). Liu et al (2015) studied several virulence genes of ETEC and constructed an attenuated strain with the λ-Red recombination system in our laboratory, but the recombination efficiency was low. Due to the complicated operation steps of three-plasmid system and the high construction cost of single-plasmid system, we selected the two-plasmid system for genetic editing in ETEC.…”