Salmonella choleraesuis C500 strain is an attenuated vaccine preventing piglet from paratyphoid and can also be used as a live vector of other DNA vaccines. Through mucosal immunization, immune response to specific antigens carried by it can be induced. To enhance the immune efficiency of DNA vaccine it carried, promoter Ptrc was inserted into the down stream of the human cytomegalovirus (CMV) immediate early promoter of eukaryotic expression plasmid pEGFP-C1. Then transcription terminator rrnbT1T2 was inserted into down stream of the multiple clone sites of pEGFP-C1, and the dual-promoter expression vector pEGFPPtrcR was constructed. Using 1xTSS method, we transformed the recombinant plasmid into C500, and obtained C500/pEGFPPtrcR. We used SDS-PAGE and Western blotting to detect the expression of report gene EGFP. Strong green fluorescence was observed under fluorescent microscope. The stable passages of this recombinant bacterium were at least 20 generations in vitro. Using liposome we transfected plasmid pEGFPPtrcR into Vero cell. After 24 h, green fluorescent was observed, showing the expression of EGFP in nuclei and endochylema. The construction of dual-promoter expression vector pEGFPPtrcR was successful. The foreign gene was expressed in Salmonella strain C500 and somatocytes, resulting in increased antigen expression. This research provides a foundation for the research of new DNA vaccines which use Salmonella C500 as carrier.
Animals ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; genetics ; metabolism ; Plasmids ; genetics ; Promoter Regions, Genetic ; genetics ; Recombinant Proteins ; genetics ; metabolism ; Salmonella Vaccines ; genetics ; immunology ; Salmonella arizonae ; genetics ; immunology ; metabolism ; Swine ; Vaccines, DNA ; genetics

The N-terminal of porcine parvovirus (PPV) viral protein 2 (VP2) links a glycine-rich domain which is a cleavage site of PPV VP3.In order to confirm that the glycine-rich domain was essential for the self-assembling of virus-like particles (VLPs).The VP2 gene with glycine-rich domain deleted and the complete VP2 gene were inserted to eukaryotic expression vector pCI-neo and were named pCI-AVP2 and pCI-VP2. Then, pCI-delta VP2, pCI-VP2 and pCI-neo were transferred into Vero Cells by liposome and the VLPs was detected by SDS-PAGE, Western blotting, indirect immunofluorescence and immunoelectron microscopy. Furthermore, 56 female Kunming mice were divided into 5 groups and injected intramuscularly with pCI-delta VP2, pCI-VP2 and pCI-neo as DNA vaccine, PPV inactivated vaccine and normal saline separately. The peripheral blood of the mice was collected to analyze the subgroups of the peripheral blood mononuclear cell by flow cytometry, to detect the antibody and lymphocyte proliferation by indirect-ELISA and MTT assay separately. The results show that the VLPs were observed both in the pCI-delta VP2 and pCI-VP2 transferred Vero Cells. The two VLPs could agglutinate guinea pig erythrocytes. The results also show that both the pCI-delta VP2 and pCI-VP2 vaccine induced special cellular and humoral immunity effectively. Those results revealed that the glycine-rich domain is not essential for the VPL's self-assembling. This study provides a new theoretical evidence for the relationship between the gene structure and protein function of VP2.
Animals ; Antigens, Viral ; genetics ; metabolism ; Capsid Proteins ; genetics ; metabolism ; Cercopithecus aethiops ; Female ; Genetic Vectors ; genetics ; Glycine ; Mice ; Sequence Deletion ; Swine ; Transfection ; Vaccination ; Vaccines, Virus-Like Particle ; biosynthesis ; immunology ; Vero Cells

To investigate the recent prevalence and molecular epidemiological characteristics of por-cine diarrhea viruses in Sichuan Province,this study used fluorescence quantitative PCR to detect porcine diarrhea samples from multiple regions in Sichuan Province from 2021 to 2023.RT-PCR was used to identify the genotypes of PEDV,PoRVA,PDCoV,and PTV,and their genetic variabil-ity,evolutionary characteristics,and recombination events were analyzed.The results showed that PEDV,PoRVA,PDCoV,and PTV were still prevalent in Sichuan region,with overall positive rates of 14.2％(40/281),13.2％(37/281),15.6％(44/281),and 12.5％(35/281),respectively.PEDV mixed infection with other pathogens was the most common.This study obtained a total of six strains of G2b PEDV,three strains of G3 PDCoV,three strains of G9P[13]PoRVA,one strain of G3P[13]PoRVA,three strains of Type 5 PTV,and one strain of Type 9 PTV.Compared to the seven vaccine strains including CV777,DR13,KPEDV-9,Chinju99,KNU-0801,AJ1102,and LW/L,the 6 PEDV strains showed multiple amino acid mutation sites in the COE region and S1D epitope region.Among them,the strains PSCLZ01 and PSCMY04 formed a separate branch in the phylogenetic tree.The three PDCoV strains have a closer genetic evolution distance to the previ-ously prevalent strains in Sichuan,but they also have 6-48 amino acid mutations compared to them.The four PoRVA strains have 104-108 amino acid variations in the VP4 gene compared to the early vaccine strain LLR,and they have 25 common amino acid variations in the VP7 gene.From the phylogenetic tree,the VP7 gene of RSCMY01/G3P[13]belongs to the same branch as the Heilongjiang strain LNCY,but its VP4 gene clusters with the Sichuan strain SCYA-C7,indica-ting that this PoRVA strain may have undergone genetic reassortment during inter-provincial transmission between different genotypes.It is worth noting that in the detected samples of PTV-5 and PTV-9,other diarrheal viruses tested negative,indicating that these two genotypes of PTV may be important pathogens causing porcine diarrhea.Additionally,the S gene of PEDV PSCLZ01 strain and PDCoV PCSCMY02 strain have undergone recombination events,and their parental strains come from different regions,both domestic and international.These findings reveal the main types of porcine diarrheal viruses,as well as their genetic diversity and variations in Sichuan Province in recent years.This study enriches the molecular epidemiological data of porcine diarrhe-al pathogens in the region and provides an important theoretical basis for the prevention,control,and purification of porcine diarrhea in the local area.