Evaluation of the Immunogenicity in Mice Orally Immunized with Recombinant Lactobacillus casei Expressing Porcine Epidemic Diarrhea Virus S1 Protein

Abstract

Porcine epidemic diarrhea (PED), characterized by diarrhea, vomiting, and dehydration, is an acute enteric infectious disease of pigs. The disease is caused by porcine epidemic diarrhea virus (PEDV), which infects the intestinal mucosal surface. Therefore, mucosal immunization through the oral route is an effective method of immunization. Lactic acid bacteria, which are acid resistant and bile-salt resistant and improve mucosal immunity, are ideal carriers for oral vaccines. The S1 glycoprotein of PEDV mediates binding of the virus with cell receptors and induces neutralizing antibodies against the virus. Therefore, we reversely screened the recombinant strain pPG-SD-S1/Δupp ATCC 393 expressing PEDV S1 glycoprotein by Lactobacillus casei deficient in upp genotype (Δupp ATCC 393). Mice were orally immunized three times with the recombinant bacteria that had been identified for expression, and the changes of anti-PEDV IgG and secreted immunoglobulin A levels were observed over 70 days. The results indicated that the antibody levels notably increased after oral administration of recombinant bacteria. The detection of extracellular cytokines on the 42nd day after immunization indicated high levels of humoral and cellular immune responses in mice. The above results demonstrate that pPG-SD-S1/Δupp ATCC 393 has great potential as an oral vaccine against PEDV.

Gut microbiome and human health: Exploring how the probiotic genus Lactobacillus modulate immune responses

“…Another in vivo study demonstrated induction of innate and adaptive immune responses by L. acidophilus NCFB 1748 and L. paracasei DC412 on BALB/c inbred mice and Fisher-344 inbred rats through polymorphonuclear (PMN) cell recruitment, TNF-α secretion and phagocytosis ( Azad et al, 2018 ). Lactobacilli encode for certain motifs within their genome, such as unmethylated CpG motifs which are recognized by TLRs that are expressed particularly in B cells and macrophages ( Xiao et al, 2022 ). The role of Lactobacillus spp.…”

Assessing immunogenicity of CRISPR-NCas9 engineered strain against porcine epidemic diarrhea virus

“…Xiao et al utilized the strain L. casei deficient in the upp gene to express the PEDV S1 protein, orally immunized mice, and measured cytokine levels. The data revealed the successful induction of Th1, Th2, and Th17 cell immune responses (Xiao et al 2022 ). Zhang et al developed the alanine racemase-deficient L. casei complementary system to express the VP4 gene of porcine rotavirus.…”

“…The plasmid pLCNICK (Song et al 2017 ), including the thermosensitive replicon, NCas 9 protein, and sgRNA sequence, was generously provided by Yang Sheng (a researcher at the Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences). Plasmids pMD-19Ts-P776 (Yin et al 2016 ), pMD-19Ts-RBS, and pMD-19Ts-S1 (Xiao et al 2022 ) were preserved in our laboratory. The PEDV LJB2019 strain was isolated from clinical samples and stored at − 140 °C to maintain its virulence.…”

“…The precipitate was incubated with 1% lysozyme and sonicated for 12% sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) detection and western blotting. SDS-PAGE was used to separate the proteins in the mixture, which were then transferred onto PVDF membranes (Millipore, Milford, MA, USA) using a mouse anti-S1 monoclonal antibody (mAb cell supernatant) prepared in our laboratory as the primary antibody (Xiao et al 2022 ). Horseradish peroxidase (HRP)-conjugated goat anti-mouse IgG antibody (Sigma, Ronkonkoma, NY, USA) was used as the secondary antibody at a dilution of 1:5000.…”

Prevention and Control of Swine Enteric Coronaviruses in China: A Review of Vaccine Development and Application

“…To date, researchers have expressed partial S protein, including the collagenase equivalent domain (COE), receptor binding domain (RBD) and S1, or the full-length S protein of individual SECs using E. coli , Lactobacillus , Bacillus subtilis , yeast, 293T cells, virus expression system (e.g., vesicular stomatitis virus, swinepox virus, pseudorabies virus, baculovirus, and human adenovirus), or transgenic plant expression systems ( Table 3 ). Among them, the immunogenicity of 14 vaccine candidates was evaluated in mice [ 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 ]. All these vaccine candidates induced high levels of the virus-specific IgG and VN antibodies in serum and cytokines in splenocytes.…”