Up-regulated lncRNA CYLD as a ceRNA of miR-2383 facilitates bovine viral diarrhea virus replication by promoting CYLD expression to counteract RIG-I-mediated type-I IFN production.

Bovine viral diarrhea virus (BVDV) is one of the most important pathogens of cattle, causing numerous economic losses to the cattle industry. To date, many potential mechanisms of BVDV evading or subverting innate immunity are still unknown. In this study, an lnc-CYLD/miR-2383/CYLD axis involved in BVDV-host interactions was screened from RNA-seq-based co-expression networks analysis of long noncoding RNAs, microRNAs and mRNAs in BVDV-infected bovine cells, and underlying mechanisms of lnc-CYLD/miR-2383/CYLD axis regulating BVDV replication were explored. Results showed that BVDV-induced up-regulation of the lnc-CYLD competed for binding to the miR-2383, and then promoted CYLD expression, thereby inhibiting RIG-I-mediated type-I interferon (IFN) production, which was subsequently confirmed by treatment with lnc-CYLD overexpression and miR-2383 inhibitor. However, miR-2383 transfection and small interfering RNA-mediated lnc-CYLD knockdown inhibited CYLD expression and enhanced RIG-I-mediated type-I IFN production, inhibiting BVDV replication. In addition, interaction relationship between lnc-CYLD and miR-2383, and colocalization relationship of lnc-CYLD, miR-2383 and CYLD were confirmed by dual-luciferase assay and in situ hybridization assay. Conclusively, up-regulation of the lnc-CYLD as a competing endogenous RNA binds to the miR-2383 to reduce inhibitory effect of the miR-2383 on the CYLD expression, playing an important role in counteracting type-I IFN-dependent antiviral immunity to facilitate BVDV replication.

A survey of jaagsiekte sheep retrovirus (JSRV) infection in sheep in the three northeastern provinces of China.

Ovine pulmonary adenomatosis (OPA) is caused by jaagsiekte sheep retrovirus (JSRV) and is a chronic, progressive, and infectious neoplastic lung disease in sheep, which causes significant economic losses to the sheep industry. Neither a vaccine nor serological diagnostic methods to detect OPA are available. We performed a JSRV infection survey in sheep using blood samples (n = 1,372) collected in the three northeastern provinces of China (i.e., Inner Mongolia, Heilongjiang, and Jilin) to determine JSRV infection status in sheep herds using a real-time PCR assay targeting the gag gene of JSRV. The ovine endogenous retrovirus sequence was successfully amplified in all sheep samples tested (296 from the Inner Mongolia Autonomous Region, 255 from Jilin province, and 821 from Heilongjiang province). Subsequently, we attempted to distinguish exogenous JSRV (exJSRV) and endogenous JSRV (enJSRV) infections in these JSRV-positive samples using a combination assay that identifies a ScaI restriction site in an amplified 229-bp fragment of the gag gene of JSRV and a "LHMKYXXM" motif in the cytoplasmic tail region of the JSRV envelope protein. The ScaI restriction site is present in all known oncogenic JSRVs but absent in ovine endogenous retroviruses, while the "LHMKYXXM" motif is in all known exJSRVs but not in enJSRVs. Interestingly, one JSRV strain (HH13) from Heilongjiang province contained the "LHMKYXXM" motif but not the ScaI enzyme site. Phylogenetic analysis showed that strain HH13 was closely related to strain enJSRV-21 reported in the USA, indicating that HH13 could be an exogenous virus. Our results provide valuable information for further research on the genetic evolution and pathogenesis of JSRV.

Immunogenicity evaluation of recombinant Lactobacillus casei W56 expressing bovine viral diarrhea virus E2 protein in conjunction with cholera toxin B subunit as an adjuvant.

BACKGROUND: Bovine viral diarrhea virus (BVDV) is one of the main causes of infectious diseases in cattle and causes large financial losses to the cattle industry worldwide. In this study, Lactobacillus casei strain W56 (Lc W56) was used as antigen deliver carrier to construct a recombinant Lactobacillus vaccine pPG-E2-ctxB/Lc W56 constitutively expressing BVDV E2 protein fused with cholera toxin B subunit (ctxB) as an adjuvant, and its immunogenicity against BVDV infection in mice model by oral route was explored. RESULTS: Our results suggested that pPG-E2-ctxB/Lc W56 can effectively activate dendritic cells (DCs) in the Peyer's patches, up-regulate the expression of Bcl-6, and promote T-follicular helper (Tfh) cells differentiation, as well as enhance B lymphocyte proliferation and promote them differentiate into specific IgA-secreting plasma cells, secreting anti-E2 mucosal sIgA antibody with BVDV-neutralizing activity. Moreover, significant levels (p < 0.01) of BVDV-neutralizing antigen-specific serum antibodies were induced in the pPG-E2-ctxB/LC W56 group post-vaccination. The recombinant Lactobacillus vaccine can induce cellular immune responses, and significant levels (p < 0.01) of Th1-associated cytokines (IL-2, IL-12, and IFN-γ), Th2-associated cytokines (IL-4, IL-10) and Th17-associated cytokine (IL-17) were determined in the serum of vaccinated mice. Significantly, the recombinant Lactobacillus vaccine provides immune protection against BVDV infection, which can be cleared effectively by the vaccine post-challenge in orally vaccinated animals. CONCLUSIONS: The genetically engineered Lactobacillus vaccine constructed in this study is immunogenic in mice and can induce mucosal, humoral, and cellular immune responses, providing effective anti-BVDV immune protection. It thus represents a promising strategy for vaccine development against BVDV.

Lactobacillus johnsonii-activated chicken bone marrow-derived dendritic cells exhibit maturation and increased expression of cytokines and chemokines in vitro.

Lactobacillus species are typical members of gut microflora that immunomodulatory effects and can regulate a variety of immune cells, such as dendritic cells (DCs). Notably, DCs possess the unique ability to initiate primary immune responses. Notably, DCs possess the unique ability to initiate primary immune responses. In this study, we investigated the effects of Lactobacillus johnsonii (L. johnsonii) on the maturation and activation of chicken bone marrow-derived dendritic cells (chBM-DCs). The chBM-DCs generated from chicken bone marrow monocytes were stimulated using lethally irradiated L. johnsonii. L. johnsonii-stimulated chBM-DCs upregulated the expression of major histocompatibility complex class II (MHC-II), CD40, and CD86, decreased phagocytosis, and increased the ability to induce the proliferation of allogeneic T cells, which displayed a mature phenotype and function. Upon maturation with L. johnsonii, the expression of Th1-type cytokines [interleukin (IL)-12, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α)], a Th2-type cytokine (IL-10), pro-inflammatory cytokines (IL-1ß and IL-6), and chemokines (CXCLi1 and CXCLi2) greatly increased; however, a high expression of IL-10 was only observed at mid-late time points for chBM-DCs stimulated with high doses of L. johnsonii. Moreover, L. johnsonii upregulated the mRNA levels of TLR2 and TLR5. These results reveal that L. johnsonii plays a potentially important role in modulating the immunological functions of chBM-DCs, suggesting that it influences and mediates immune responses in vitro.

Protection Efficacy of Oral Bait Probiotic Vaccine Constitutively Expressing Tetravalent Toxoids against Clostridium perfringens Exotoxins in Livestock (Rabbits).

Clostridium perfringens is an opportunistic pathogen. Its main virulence factors are exotoxins, which are the etiological agents of enteritis necroticans and enterotoxemia caused in livestock (cattle, sheep, and rabbits). Here, we demonstrated effective immune protection for rabbits against α, ß, and ε exotoxins of C. perfringens provided by an oral tetravalent bait probiotic vaccine delivering α, ε, ß1, and ß2 toxoids of C. perfringens. Results showed that the recombinant probiotic had good segregational stability and good colonization ability in the rabbit intestinal tract. Oral administration of the probiotic vaccine can effectively elicit significant levels of antigen-specific mucosa sIgA and sera IgG antibodies with exotoxin-neutralizing activity. Additionally, oral immunization with the probiotic vaccine effectively promoted lymphoproliferation and Th1/Th2-associated cytokine production. The protection rate of immunized rabbits with the probiotic vaccine was 80% after challenging rabbits with a combination of C. perfringens (toxinotypes A, C, and D) and exotoxin mixture, which was better than the 60% provided by a commercial inactivated C. perfringens A, C, and D trivalent vaccine. Moreover, obvious histopathological changes were observed in the intestinal tissues of rabbits in the commercial vaccine and PBS groups. The bait probiotic vaccine can provide effective protection against C. perfringens exotoxins, suggesting a promising C. perfringens vaccination strategy.

Screening and Identification of a Chicken Dendritic Cell Binding Peptide by Using a Phage Display Library.

Dendritic cells (DCs), as antigen-presenting cells, can initiate adaptive immune responses efficiently. Although the DC-targeting strategy has attracted more attention, relevant studies on chicken are rare. Here, specific chicken bone marrow DC-binding peptides were selected using a phage display peptide library and confirmed through ELISA, flow cytometry, fluorescence microscopy, and laser confocal microscopy. The peptide candidate SPHLHTSSPWER, named SP, was fused to the infectious bursal disease virus (IBDV) structural protein and protective antigen VP2. In vitro, the expression of DC markers (CD80, CD83, CD86, DEC205, and MHCII) and some cytokines (IFN-γ, IL-12, TNF-α, IL-1ß, IL-6, and CXCLi1) by VP2-SP-stimulated DCs was significantly higher than that by DCs treated with the VP2-control peptide at 4 h (p < 0.001). In addition, an oral vaccine targeting DCs was generated using chicken-borne Lactobacillus saerimneri M11 (L. sae M11) to deliver VP2 fused with SP. Anti-IBDV mucosal and humoral immune responses were induced efficiently via oral administration, resulting in higher protective efficacy in the VP2-SP group than the VP2 group. Therefore, chicken DC targeting of IBDV protective antigen VP2 delivered by L. sae provides effective immune protection in chicken. Our study may promote research on the DC-targeting strategy to enhance the effectiveness of chicken vaccines.

An EGFP-marked recombinant lactobacillus oral tetravalent vaccine constitutively expressing α, ε, ß1, and ß2 toxoids for Clostridium perfringens elicits effective anti-toxins protective immunity.

Clostridium perfringens is a common opportunistic pathogen endangering livestock and poultry breeds. Here, using enhanced green fluorescent protein as screening marker, a recombinant lactobacillus tetravalent vaccine constitutively expressing α, ε, ß1, and ß2 toxoids of C. perfringens was developed, and its immunogenicity in mice was investigated via oral administration. This probiotic vaccine could effectively induce antigen-specific secretory IgA (sIgA)-based mucosal and IgG-based humoral immune responses, and significantly high levels (p< 0.05) of cytokines IL-2, IL-4, IL-10, IL-12, IL-17, and IFN-γ were produced in immunized mice. Moreover, lymphoproliferation and percentage of CD4+ and CD8+ T cells significantly increased in mice of the probiotic vaccine group. Challenge experiments were performed in mice with C. perfringens toxinotypes A, C, and D crude toxins to evaluate protection efficiency of the probiotic vaccine, using a commercial inactivated C. perfringens vaccine made by C. perfringens toxinotypes A, C, and D as vaccine control. We observed 80% protection rate in the probiotic vaccine group, which was higher than commercial vaccine group, whereas all mice in control groups died and obvious histopathological changes were observed in liver, spleen, kidney, and intestines of mice. Significantly, we compared the immunogenicity and protection efficiency of lactobacillus constitutive expression system and lactobacillus inducible expression system, and results showed that lactobacillus constitutive expression system has obvious advantages. Our study clearly demonstrated that the probiotics vaccine could effectively induce mucosal, humoral, and cellular immunity, and provide effective protection against C. perfringens toxins, suggesting a promising strategy for the development of oral vaccine against C. perfringens.

Dendritic Cell Targeting of Bovine Viral Diarrhea Virus E2 Protein Expressed by Lactobacillus casei Effectively Induces Antigen-Specific Immune Responses via Oral Vaccination.

Bovine viral diarrhea caused by bovine viral diarrhea virus (BVDV) is an important disease in cattle, resulting in significant economic losses to the cattle industry worldwide. In order to develop an effective vaccine against BVDV infection, we constructed a dendritic cell (DC)-targeting oral probiotic vaccine (pPG-E2-DCpep/LC W56) using Lactobacillus casei as antigen delivery carrier to express BVDV glycoprotein E2 fused with DC-targeting peptide, and the immunogenicity of orally administered probiotic vaccine was evaluated in mice model. Our results showed that after immunization with the probiotic vaccine, significantly levels of antigen-specific sera IgG and mucosal sIgA antibodies (p < 0.05) with BVDV-neutralizing activity were induced in vivo. Challenge experiment showed that pPG-E2-DCpep/LC W56 can provide effective immune protection against BVDV, and BVDV could be effectively cleared from the intestine of immunized mice post-challenge. Moreover, the pPG-E2-DCpep/LC W56 could efficiently activate DCs in the intestinal Peyer's patches, and significantly levels of lymphoproliferative responses, Th1-associated IFN-γ, and Th2-associated IL-4 were observed in mice immunized with pPG-E2-DCpep/LC W56 (p < 0.01). Our results clearly demonstrate that the probiotic vaccine could efficiently induce anti-BVDV mucosal, humoral, and cellular immune responses via oral immunization, indicating a promising strategy for the development of oral vaccine against BVDV.

N-linked glycosylation sites in G protein of infectious hematopoietic necrosis virus (IHNV) affect its virulence and immunogenicity in rainbow trout.

Infectious hematopoietic necrosis virus (IHNV) causes infectious hematopoietic necrosis in salmonid fish, resulting in substantial economic losses to the aquaculture industry worldwide. The G protein, which harbors the major antigenic determinants of IHNV, is an envelope glycoprotein that plays an important role in both pathogenicity and immunogenicity of IHNV. Previous studies have demonstrated that changes to viral glycosylation sites may affect replication and immunogenicity, but little is known about the specific contributions of G protein glycosylation to IHNV replication and pathogenicity. In this study, we predicted four N-linked glycosylation sites at position 56, 379, 401, and 438 Asp (N) in G protein, and using a reverse genetics system developed in our laboratory, constructed nine recombinant viruses with single, triple, or quadruple glycosylation site disruptions using alanine substitutions in the following combinations: rIHNV-N56A, rIHNV-N379A, rIHNV-N401A, rIHNV-N438A, rIHNV-N56A-N379A-N401A, rIHNV-N56A-N379A-N438A, rIHNV-N56A-N401A-N438A, rIHNV-N379A-N401A-N438A, and rIHNV-N56A-N379A-N401A-N438A. Our results confirmed that all four asparagines are sites of N-linked glycosylation, and Western blot confirmed that mutation of each predicted N-glycosylation sited impaired glycosylation. Among the nine recombinant IHNVs, replication levels decreased significantly in vitro and in vivo in the triple and quadruple mutants that combined mutation of asparagines 401 and 438, indicating the importance of glycosylation at these sites for efficient replication. Moreover, juvenile rainbow trout mortality after challenge by each of the nine mutants showed that, while eight mutants suffered almost 100% cumulative mortality over 30 days, the mutant with a single alanine substitution at position 438 resulted in cumulative mortality of less than 50% over 30 days. This mutant also elicited specific anti-IHNV IgM production earlier than other mutants, suggesting that glycosylation of asparagine 438 may be important for viral immune escape. In conclusion, our study reveals the effect of G protein glycosylation on the pathogenicity and immunogenicity of IHNV and provides a foundation for developing a live-attenuated vaccine.

Porcine transmissible gastroenteritis virus nonstructural protein 2 contributes to inflammation via NF-κB activation.

Transmissible gastroenteritis virus (TGEV) infection causes acute enteritis in swine of all ages, and especially in suckling piglets. Small intestinal inflammation is considered a central event in the pathogenesis of TGEV infections, and nuclear factor-kappa B (NF-κB) is a key transcription factor in the inflammatory response. However, it is unclear whether NF-κB is crucial for inducing inflammation during a TGEV infection. Our results show that NF-κB was activated in swine testicular (ST) cells and intestinal epithelial cell lines J2 (IPEC-J2) cells infected with TGEV, which is consistent with the up-regulation of pro-inflammatory cytokines. Treatment of TGEV-infected ST cells and IPEC-J2 cells with the NF-κB-specific inhibitor caused the down-regulation of pro-inflammatory cytokine expression, but did not significantly affect TGEV replication. Individual TGEV protein screening results demonstrated that Nsp2 exhibited a high potential for activating NF-κB and enhancing the expression of pro-inflammatory cytokines. Functional domain analyzes indicated that the first 120 amino acid residues of Nsp2 were essential for NF-κB activation. Taken together, these data suggested that NF-κB activation was a major contributor to TGEV infection-induced inflammation, and that Nsp2 was the key viral protein involved in the regulation of inflammation, with amino acids 1-120 playing a critical role in activating NF-κB. Abbreviations: TCID50: 50% tissue culture infectious dose; DMEM: Dulbecco's Modified Eagle Medium; eNOS: Endothelial nitric oxide synthase; FBS: fetal bovine serum; IFA: Indirect immunofluorescence; IκB: inhibitor of nuclear factor kappa-B; IL: interleukin; IPEC-J2: intestinal epithelial cell lines J2; IKK: IκB kinase; Luc: luciferase reporter gene; mAbs: monoclonal antibodies; MOI: multiple of infection; Nsp: nonstructural protein; NF-κB: nuclear factor-kappa ; ORFs: open reading frames; PBS: phosphate-buffered saline; p65 p-p65: phosphorylated; RT-PCR: reverse transcription PC; SeV: Sendai virus; ST: swine testicular; TGEV: Transmissible gastroenteritis virus; TNF-α: tumor necrosis factor α; UV-TGEV: Ultraviolet light-inactivated TGEV; ZnF: zinc finger.

Construction and characterization of thymidine auxotrophic (ΔthyA) recombinant Lactobacillus casei expressing bovine lactoferricin.

BACKGROUND: Lactobacillus casei (L. casei) is well known for its probiotic property in human and animals. Lactoferricin (Lfcin) polypeptide can effectively modulate host immune responses and have antimicrobial activity in vivo and in vitro. In order to develop a food-grade L. casei system constitutively expressing bovine Lfcin, this study constructed a thymidine auxotrophy (ΔthyA) recombinant L. casei. RESULTS: Based on the thymidylate synthase gene (thyA) insert site, LFEC(Lfcin expression cassette)was inserted into L. casei genome through homologous recombination, successfully expressed and could be stably inherited. The recombinant L. casei, ΔthyA L. casei-LFEC, is sensitive to chloramphenicol and limited when cultured without thymine. Meanwhile, ΔthyA L. casei-LFEC has both good antibacterial activity against Escherichia coli and Staphylococcus aureus and antiviral activity against porcine epidemic diarrhea virus (PEDV). CONCLUSIONS: We successfully constructed a recombinant L. casei strain expressing Lfcin, ΔthyA L. casei-LFEC, which could only survive in the presence of thymine, and had excellent antimicrobial and antiviral activity with good genetic stability and sensitivity. This research provides a cost-effective alternative to the antibiotics with additional biological functions and wider applicability prospect. Using ΔthyA as the selectable mark instead of antibiotic to construct genetic engineering L.casei provides a safe and effective approach of feed additives in livestock raising.

Identification of amino acid residues in infectious hematopoietic necrosis virus (IHNV) NV protein necessary for viral replication and pathogenicity.

Our previous studies demonstrated that the nonstructural NV protein of infectious hematopoietic necrosis virus (IHNV) was essential for efficient viral replication and pathogenicity, and that the amino acid residues 32EGDL35 of the NV protein were responsible for nuclear localization, and played important roles in suppressing IFN and inhibiting NF-κB activity. However, little is known about the influence of 32EGDL35 on IHNV replication and pathogenicity. In the present study, two recombinant IHNV strains with deletions of NV 32EGDL35 were generated and the effect on IHNV replication and pathogenicity was explored. Our results showed that both mutants stably replicated in Chinook salmon embryo cells for 15 consecutive passages, and had similar host-tropism as wild-type (wt) IHNV; however, titers of the mutants were lower than those of wt IHNV in CHSE-214 cells. Infection of rainbow trout showed wt IHNV produced 90% cumulative mortality, while the mutants produced 55% and 60% cumulative mortality, respectively. Histopathological evaluation showed that tissues from the liver, brain, kidney, and heart of fish infected with wt IHNV exhibited pathological changes, but significant lesions were found only in the liver and heart of fish infected with the recombinant viruses. In addition, the recombinant viruses induced higher expression levels of IFN1, Mx-1, and IL-6 compared with those induced by wt IHNV. These results indicated that the 32EGDL35 residues were essential for the efficient anti-IFN and NF-κB-inhibiting activity of NV. Our results provide a basis for understanding the roles of 32EGDL35 in IHNV replication and pathogenicity, and may prove beneficial in the prevention and control of IHNV infections of fish.

Oral Delivery of Probiotics Expressing Dendritic Cell-Targeting Peptide Fused with Porcine Epidemic Diarrhea Virus COE Antigen: A Promising Vaccine Strategy against PEDV.

Porcine epidemic diarrhea virus (PEDV), an enteric coronavirus, is the causative agent of porcine epidemic diarrhea (PED) that damages intestinal epithelial cells and results in severe diarrhea and dehydration in neonatal suckling pigs with up to 100% mortality. The oral vaccine route is reported as a promising approach for inducing protective immunity against PEDV invasion. Furthermore, dendritic cells (DCs), professional antigen-presenting cells, link humoral and cellular immune responses for homeostasis of the intestinal immune environment. In this study, in order to explore an efficient oral vaccine against PEDV infection, a mucosal DC-targeting oral vaccine was developed using Lactobacillus casei to deliver the DC-targeting peptide (DCpep) fused with the PEDV core neutralizing epitope (COE) antigen. This probiotic vaccine could efficiently elicit secretory immunoglobulin A (SIgA)-based mucosal and immunoglobulin G (IgG)-based humoral immune responses via oral vaccination in vivo. Significant differences (p < 0.05) in the immune response levels were observed between probiotics expressing the COE-DCpep fusion protein and COE antigen alone, suggesting better immune efficiency of the probiotics vaccine expressing the DC-targeting peptide fused with PEDV COE antigen. This mucosal DC-targeting oral vaccine delivery effectively enhances vaccine antigen delivery efficiency, providing a useful strategy to induce efficient immune responses against PEDV infection.

The role of infectious hematopoietic necrosis virus (IHNV) proteins in the modulation of NF-κB pathway during IHNV infection.

Viral infections frequently lead to the activation of host innate immune signaling pathways involved in the defense against invading pathogens. To ensure their survival, viruses have evolved sophisticated mechanisms to overcome the host immune responses. The present study demonstrated for the first time that infectious hematopoietic necrosis virus (IHNV) activated NF-κB pathway in fish cells. We further identified that the IHNV L protein could activate the NF-κB signaling pathway and that IHNV NV functioned as an inhibitor of NF-κB activation. Further results demonstrated that the NV protein blocked the degradation of the inhibitor of NF-κB (IκBα) and suppressed the SeV-induced NF-κB nuclear translocation. In conclusion, our study explored the functions of different IHNV proteins on NF-κB activation, and revealed a potential mechanism by which IHNV evades innate immune responses.

Use of dual priming oligonucleotide system-based multiplex RT-PCR combined with high performance liquid chromatography assay for simultaneous detection of five enteric viruses associated with acute enteritis.

In this study, a specific and sensitive method for simultaneous detection of human astrovirus, human rotavirus, norovirus, sapovirus and enteric adenovirus associated with acute enteritis was developed, based on the specific dual priming oligonucleotide (DPO) system and the sensitive high-performance liquid chromatography (HPLC) analysis. The DPO system-based multiplex reverse transcription-polymerase chain reaction (RT-PCR) combined with HPLC assay was more sensitive than agarose gel electrophoresis analysis and real-time SYBR Green PCR assay, and showed a specificity of 100% and sensitivity of 96%-100%. The high sensitivity and specificity of the assay indicates its great potential to be a useful tool for the accurate diagnosis of enteric virus infections.

Novel Approach for Isolation and Identification of Porcine Epidemic Diarrhea Virus (PEDV) Strain NJ Using Porcine Intestinal Epithelial Cells.

Porcine epidemic diarrhea virus (PEDV), which is the causative agent of porcine epidemic diarrhea in China and other countries, is responsible for serious economic losses in the pork industry. Inactivated PEDV vaccine plays a key role in controlling the prevalence of PEDV. However, consistently low viral titers are obtained during the propagation of PEDV in vitro; this represents a challenge to molecular analyses of the virus and vaccine development. In this study, we successfully isolated a PEDV isolate (strain NJ) from clinical samples collected during a recent outbreak of diarrhea in piglets in China, using porcine intestinal epithelial cells (IEC). We found that the isolate was better adapted to growth in IECs than in Vero cells, and the titer of the IEC cultures was 104.5 TCID50/0.1 mL at passage 45. Mutations in the S protein increased with the viral passage and the mutations tended towards attenuation. Viral challenge showed that the survival of IEC-adapted cultures was higher at the 45th passage than at the 5th passage. The use of IECs to isolate and propagate PEDV provides an effective approach for laboratory-based diagnosis of PEDV, as well as studies of the epidemiological characteristics and molecular biology of this virus.

[Determination of 16 pesticide residues in fruits and vegetables by QuEChERS-liquid chromatography-tandem mass spectrometry].

A sensitive and convenient liquid chromatography-tandem mass spectrometric method was developed for the determination of 16 pesticides such as imidacloprid, prochloraz, difenoconazole, azoxystrobin, and thiamethoxam in fruits and vegetables. After compared with methanol and acetone-cyclohexane (1:2, v/v), acetonitrile was chosen as the extraction solvent. The samples were extracted by acetonitrile in high-speed homogenization. The extraction solution was cleaned up by liquid-liquid extraction, and the supernatant was collected. In this work, QuEChERS exhibited much higher efficiency than Carbon-NH2 solid-phase extraction in purification. The pigments and organic acids were removed by purge line (150 mg primary secondary amine (PSA) sorbent and 900 mg absolute magnesium sulfate), leading to the decrease of the background interferences. The average recoveries of the 16 pesticides were almost in the range of 75%-111% at the three spiked levels, and the relative standard deviations were less than 16%. The qualitative analysis and quantitative analysis were investigated by LC-MS/MS and matrix-matched calibration curves. The results showed that the method of QuEChERS combined with LC-MS/MS is rapid, accurate and sensitive for the determination of the 16 pesticide residues in fruits and vegetables.

Immunogenicity in Swine of Orally Administered Recombinant Lactobacillus plantarum Expressing Classical Swine Fever Virus E2 Protein in Conjunction with Thymosin α-1 as an Adjuvant.

Classical swine fever, caused by classical swine fever virus (CSFV), is a highly contagious disease that results in enormous economic losses in pig industries. The E2 protein is one of the main structural proteins of CSFV and is capable of inducing CSFV-neutralizing antibodies and cytotoxic T lymphocyte (CTL) activities in vivo. Thymosin α-1 (Tα1), an immune-modifier peptide, plays a very important role in the cellular immune response. In this study, genetically engineered Lactobacillus plantarum bacteria expressing CSFV E2 protein alone (L. plantarum/pYG-E2) and in combination with Tα1 (L. plantarum/pYG-E2-Tα1) were developed, and the immunogenicity of each as an oral vaccine to induce protective immunity against CSFV in pigs was evaluated. The results showed that recombinant L. plantarum/pYG-E2 and L. plantarum/pYG-E2-Tα1 were both able to effectively induce protective immune responses in pigs against CSFV infection by eliciting immunoglobulin A (IgA)-based mucosal, immunoglobulin G (IgG)-based humoral, and CTL-based cellular immune responses via oral vaccination. Significant differences (P < 0.05) in the levels of immune responses were observed between L. plantarum/pYG-E2-Tα1 and L. plantarum/pYG-E2, suggesting a better immunogenicity of L. plantarum/pYG-E2-Tα1 as a result of the Tα1 molecular adjuvant that can enhance immune responsiveness and augment specific lymphocyte functions. Our data suggest that the recombinant Lactobacillus microecological agent expressing CSFV E2 protein combined with Tα1 as an adjuvant provides a promising strategy for vaccine development against CSFV.

[The oral immune efficacy of recombinant lactobacillus casei expressing CSFV E290 peptide and it elicited specific CTL response].

UNLABELLED: The gene encoding classical swine fever virus (CSFV) T cell epitope E290 peptide was synthesized by PCR, cloned into the expression vector pPG-VP2 and named pPG-VP2-E290. The recombinant plasmid was electrotransformed into Lactobacillus casei 393 generating pPG-VP2-E290/L. casei 393. Specific anti-CSFV E290 peptide immunoglobulin G (IgG) antibody was detected by indirect ELISA in the serum of BALB/c mice and rabbits immunized with recombinant strain by oral administration. The CTL of E290 was analyzed with lymphocytes taken from the immunized mice, and the immunized rabbits were attacked with CSFV to validate the protective function of E290 antibody induced. RESULT: The recombinant expression system constructed with L. casei 393 in this study show a good immunization property and could elicit the mice and rabbits to produce high anti-E290 antibody levels. Furthermore, E290 peptide antibody could elicit specific CTL response, and restrain attack of CSFV to rabbits.

[Construction of recombinant Lactococcus lactis expressing porcine transmissible gastroenteritis spike glycoprotein and analysis of immunogenicity].

Transmissible gastroenteritis virus (TGEV), is an enteropathogenic coronavirus that causes a highly fatal acute diarrhea in newborn pigs. It's typically clinical manifestations consist of omitting, severe diarrhea, loss water and highly infectious disease. All kinds and ages of pigs can be infected. Particular, the mortality piglets under 3 weeks may reach 100% . The effective protection against TGEV requires the development of vaccines that are able to induce local mucosal immunization. Lactococcus lactis was selected as a bacterial carrier for the expression of TGEV spike glycoprotein. The gene of S glycoprotein was cloned into the Lactococcus lactis vectors pNZ8112. An approximately 2000 bps fragments of TGEV gene S that encompasses all the four major antigenic domains critical for neutralization was transformed into Lactococcus lactis NZ9000 by electroporation, resulting in the recombinant strain pNZ8112-Sa/NZ9000. The recombinant glycoprotein S was detected by SDS-PAGE and Western blot after induced by 1ng/mL nisin. The result indicated that the expressed product maintain the antigenicity of TGEV as expected. In order to detect the location of expressed protein, the yellow and green fluorescence of the recombinant strain pNZ8112-Sa/NZ9000 was detected by the IFA experiments, which indicated that the expressed recombinant protein was secreted and located on the surface of the bacterium cell. Oral immunization of BALB/c mice with recombinant strain that constitutively express the 66kDa fragment of the glycoprotein S, Specific anti-TGEV glycoprotein S secret immunoglobulin A (sIgA) antibodies were detected by indirect enzyme linked immunosorbent assay (ELISA) in the feces after immunization. It was showed that the mice immunized with pNZ8112-Sa/NZ9000 recombinant strain had produced clear antibody level anti TGEV, and which had provided important substance foundation and explored the feasibility of Lactobacillus as oral vaccine.