SARS-CoV-2 prevalence in wildlife 2020-2022: a worldwide systematic review and meta-analysis.

The widespread transmission of SARS-CoV-2 in humans poses a serious threat to public health security, and a growing number of studies have discovered that SARS-CoV-2 infection in wildlife and mutate over time. This article mainly reports the first systematic review and meta-analysis of the prevalence of SARS-CoV-2 in wildlife. The pooled prevalence of the 29 included articles was calculated by us using a random effects model (22.9%) with a high heterogeneity (I2 = 98.7%, p = 0.00). Subgroup analysis and univariate regression analysis found potential risk factors contributing to heterogeneity were country, wildlife species, sample type, longitude, and precipitation. In addition, the prevalence of SARS-CoV-2 in wildlife increased gradually over time. Consequently, it is necessary to comprehensively analyze the risk factors of SARS-CoV-2 infection in wildlife and develop effective control policies, as well as to monitor the mutation of SARS-CoV-2 in wildlife at all times to reduce the risk of SARS-CoV-2 transmission among different species.

Preventive and Therapeutic Potential of Streptococcus cristatus CA119 in Experimental Periodontitis in Rats.

Periodontitis is an inflammatory condition of the oral cavity caused by a mixed infection of various bacteria, which not only severely affects the alveolar bone and connective tissues but also displays potential correlations with distal intestinal inflammation. In this study, we aimed to elucidate the therapeutic effects of Streptococcus cristatus CA119 on experimental periodontitis in rats and its impact on intestinal morphology. The results demonstrate that CA119 is capable of colonizing the oral cavity and exerting antagonistic effects on Porphyromonas gingivalis and Fusobacterium nucleatum, thus leading to a significant reduction in the oral pathogen load. Following CA119 intervention, there was a significant alleviation of weight loss in rats induced by periodontitis (P < 0.001). CA119 also regulated the expression of IL-6 (P < 0.05), IL-1ß (P < 0.001), IL-18 (P < 0.001), COX-2 (P < 0.001), iNOS (P < 0.001), and MCP-1 (P < 0.01) in the gingival tissue. Additionally, CA119 reduced oxidative stress levels in rats and enhanced their antioxidant capacity. Microcomputed tomography (micro-CT) and histological analysis revealed that CA119 significantly reduced alveolar bone loss and reversed the downregulation of OPG/RANKL (P < 0.001). Furthermore, CA119 exhibited a significant protective effect against intestinal inflammation induced by periodontal disease and improved the colonic morphology in rats. In conclusion, this study demonstrates the role of CA119 as a potential oral probiotic in the prevention and treatment of experimental periodontitis, underscoring the potential of probiotics as a complementary approach to traditional periodontal care.

Inhibitory Effect of Lactococcus and Enterococcus faecalis on Citrobacter Colitis in Mice.

Probiotics are beneficial for intestinal diseases. Research shows that probiotics can regulate intestinal microbiota and alleviate inflammation. Little research has been done on the effects of probiotics on colitis in mice. The purpose of this study was to investigate the inhibitory effect of the strains isolated and screened from the feces of healthy piglets on the enteritis of rocitrobacter. The compound ratio of isolated Lactobacillus L9 and Enterococcus faecalis L16 was determined, and the optimal compound ratio was selected according to acid production tests and bacteriostatic tests in vitro. The results showed that when the ratio of Lactobacillus L9 to Enterococcus faecalis L16 was 4:1, the pH value was the lowest, and the antibacterial diameter was the largest. Then, in animal experiments, flow cytometry was used to detect the number of T lymphocytes in the spleen and mesenteric lymph nodes of mice immunized with complex lactic acid bacteria. The results showed that the number of T lymphocytes in the spleen and mesenteric lymph nodes of mice immunized with complex lactic acid bacteria significantly increased, which could improve the cellular immunity of mice. The microbiota in mouse feces were sequenced and analyzed, and the results showed that compound lactic acid bacteria could increase the diversity of mouse microbiota. It stabilized the intestinal microbiota structure of mice and resisted the damage of pathogenic bacteria. The combination of lactic acid bacteria was determined to inhibit the intestinal colitis induced by Citrobacter, improve the cellular immune response of the body, and promote the growth of animals.

The Acetic Acid Produced by Lactobacillus Species Regulates Immune Function to Alleviate PEDV Infection in Piglets.

Porcine epidemic diarrhea virus (PEDV) infection results in significant mortality among newborn piglets, leading to substantial economic setbacks in the pig industry. Short-chain fatty acids (SCFA), the metabolites of intestinal probiotics, play pivotal roles in modulating intestinal function, enhancing the intestinal barrier, and bolstering immune responses through diverse mechanisms. The protective potential of Lactobacillus delbrueckii, Lactobacillus johnsonii, and Lactococcus lactis was first noted when administered to PEDV-infected piglets. Histological evaluations, combined with immunofluorescence studies, indicated that piglets receiving L. lactis displayed less intestinal damage, with diminished epithelial cell necrosis and milder injury levels. Differences in immunofluorescence intensity revealed a significant disparity in antigen content between the L. lactis and PEDV groups, suggesting that L. lactis might suppress PEDV replication, the intestine. We then assessed short-chain fatty acid content through targeted metabolomics, finding that acetate levels markedly varied from other groups. This protective impact was confirmed by administering acetate to PEDV-infected piglets. Data suggested that piglets receiving acetate exhibited resistance to PEDV. Flow cytometry analyses were conducted to evaluate the expression of innate and adaptive immune cells in piglets. Sodium acetate appeared to bolster innate immune defenses against PEDV, marked by elevated NK cell and macrophage counts in mesenteric lymph nodes, along with increased NK cells in the spleen and macrophages in the bloodstream. Acetic acid was also found to enhance the populations of CD8+ IFN-γ T cells in the blood, spleen, and mesenteric lymph, CD4+ IFN-γ T cells in mesenteric lymph nodes and spleen, and CD4+ IL-4+T cells in the bloodstream. Transcriptome analyses were carried out on the jejunal mucosa from piglets with PEDV-induced intestinal damage and from healthy counterparts with intact barriers. Through bioinformatics analysis, we pinpointed 189 significantly upregulated genes and 333 downregulated ones, with the PI3K-AKT, ECM-receptor interaction, and pancreatic secretion pathways being notably enriched. This transcriptomic evidence was further corroborated by western blot and qPCR. Short-chain fatty acids (SCFA) were found to modulate G protein-coupled receptor 41 (GPR41) and 43 (GPR43) in porcine intestinal epithelial cells (IPEC-J2). Post-acetic acid exposure, there was a notable upsurge in the ZO-1 barrier protein expression in IPEC-J2 compared to the unexposed control group (WT), while GPR43 knockdown inversely affected ZO-1 expression. Acetic acid amplified the concentrations of phosphorylated PI3K and AKT pivotal components of the PI3K/AKT pathway. Concurrently, the co-administration of AKT agonist SC79 and PI3K inhibitor LY294002 revealed acetic acid's role in augmenting ZO-1 expression via the P13K/AKT signaling pathway. This study demonstrates that acetic acid produced by Lactobacillus strains regulates intestinal barrier and immune functions to alleviate PEDV infection. These findings provide valuable insights for mitigating the impact of PEDV in the pig industry.

Bacillus halotolerans SW207 alleviates enterotoxigenic Escherichia coli-induced inflammatory responses in weaned piglets by modulating the intestinal epithelial barrier, the TLR4/MyD88/NF-κB pathway, and intestinal microbiota.

Enterotoxigenic Escherichia coli (ETEC) is one of the major pathogens contributing to piglet diarrhea, with significant implications for both piglet health and the economic aspects of the livestock industry. SW207 is an isolate of Bacillus halotolerans isolated from the cold- and disease-resistant Leixiang pigs in Northeastern China. We have discovered that SW207 can survive in the pig's gastrointestinal fluid and under conditions of high bile salt concentration, displaying potent antagonistic activity against ETEC. In this study, we established a weaned piglet diarrhea model infected with ETEC to investigate the role of SW207 in preventing diarrhea and improving intestinal health. Results indicate that SW207 upregulates the expression of tight junction proteins, including claudin-1, occludin, and zonula occludens-1, at both the transcriptional and translational levels. Furthermore, SW207 reduces serum endotoxin, D-lactic acid, and various oxidative stress markers while enhancing piglet mechanical barrier function. In terms of immune barrier, SW207 suppressed the activation of the TLR4/MyD88/NF-κB pathway, reducing the expression of various inflammatory factors and upregulating the expression of small intestine mucosal sIgA. Concerning the biological barrier, SW207 significantly reduces the content of E. coli in the intestines and promotes the abundance of beneficial bacteria, thereby mitigating the microbiota imbalance caused by ETEC. In summary, SW207 has the potential to prevent weaned piglet diarrhea caused by ETEC, alleviate intestinal inflammation and epithelial damage, and facilitate potential beneficial changes in the intestinal microbiota. This contributes to elucidating the potential mechanisms of host-microbe interactions in preventing pathogen infections.IMPORTANCEEnterotoxigenic Escherichia coli (ETEC) has consistently been one of the significant pathogens causing mortality in weaned piglets in pig farming. The industry has traditionally relied on antibiotic administration to control ETEC-induced diarrhea. However, the overuse of antibiotics has led to the emergence of drug-resistant zoonotic bacterial pathogens, posing a threat to public health. Therefore, there is an urgent need to identify alternatives to control pathogens and reduce antibiotic usage. In this study, we assessed the protective effect of a novel probiotic in a weaned piglet model infected with ETEC and analyzed its mechanisms both in vivo and in vitro. The study results provide theoretical support and reference for implementing interventions in the gut microbiota to alleviate early weaned piglet diarrhea and improve intestinal health.

Immunogenicity and protective efficacy of a novel bacterium-like particle-based vaccine displaying canine distemper virus antigens in mice and dogs.

Canine distemper virus (CDV) poses a severe threat to both domesticated and wild animals, including multiple carnivores. With the continued expansion of its host range, there is an urgent need for the development of a safer and more effective vaccine. In this study, we developed subunit vaccines based on a bacterium-like particle (BLP) delivery platform containing BLPs-F and BLPs-H, which display the CDV F and H glycoprotein antigens, respectively, using the antigen-protein anchor fusions produced by a recombinant baculovirus insect cell expression system. The combination of BLPs-F and BLPs-H (CDV-BLPs), formulated with colloidal manganese salt [Mn jelly (MnJ)] adjuvant, triggered robust CDV-specific antibody responses and a substantial increase in the number of interferon gamma (IFN-γ)-secreting CD4+ and CD8+ T cells in mice. Dogs immunized intramuscularly with this vaccine not only produced CDV-specific IgG but also displayed elevated concentrations of IFN-γ and interleukin 6 in their serum, along with an increase of the CD3+CD4+ and CD3+CD8+ T cell subsets. Consequently, this heightened immune response provided effective protection against disease development and reduced viral shedding levels following challenge with a virulent strain. These findings suggest that this BLP-based subunit vaccine has the potential to become a novel canine distemper vaccine. IMPORTANCE: Many sensitive species require a safe and effective distemper vaccine. Non-replicating vaccines are preferred. We constructed subunit particles displaying canine distemper virus (CDV) antigens based on a bacterium-like particle (BLP) delivery platform. The CDV-BLPs formulated with theMn jelly adjuvant induced robust humoral and cell-mediated immune responses to CDV in mice and dogs, thereby providing effective protection against a virulent virus challenge. This work is an important step in developing a CDV subunit vaccine.

The protective effect of intranasal immunization with influenza virus recombinant adenovirus vaccine on mucosal and systemic immune response.

Influenza virus is a kind of virus that poses several hazards of animal and human health. Therefore, it is important to develop an effective vaccine to prevent influenza. To this end we successfully packaged recombinant adenovirus rAd-NP-M2e-GFP expressing multiple copies of influenza virus conserved antigens NP and M2e and packaged empty vector adenovirus rAd-GFP. The effect of rAd-NP-M2e-GFP on the activation of dendritic cell (DC) in vitro and in vivo was detected by intranasal immunization. The results showed that rAd-NP-M2e-GFP promoted the activation of DC in vitro and in vivo. After the primary immunization and booster immunization of mice through the nasal immune way, the results showed that rAd-NP-M2e-GFP induced enhanced local mucosal-specific T cell responses, increased the content of SIgA in broncho alveolar lavage fluids (BALF) and triggered the differentiation of B cells in the germinal center. It is proved that rAd-NP-M2e-GFP can significantly elicit mucosal immunity and systemic immune response. In addition, rAd-NP-M2e-GFP could effectively protect mice after H1N1 influenza virus challenge. To lay the foundation and provide reference for further development of influenza virus mucosal vaccine in the future.

Gut microbiota-derived LCA mediates the protective effect of PEDV infection in piglets.

BACKGROUND: The gut microbiota is a critical factor in the regulation of host health, but the relationship between the differential resistance of hosts to pathogens and the interaction of gut microbes is not yet clear. Herein, we investigated the potential correlation between the gut microbiota of piglets and their disease resistance using single-cell transcriptomics, 16S amplicon sequencing, metagenomics, and untargeted metabolomics. RESULTS: Porcine epidemic diarrhea virus (PEDV) infection leads to significant changes in the gut microbiota of piglets. Notably, Landrace pigs lose their resistance quickly after being infected with PEDV, but transplanting the fecal microbiota of Min pigs to Landrace pigs alleviated the infection status. Macrogenomic and animal protection models identified Lactobacillus reuteri and Lactobacillus amylovorus in the gut microbiota as playing an anti-infective role. Moreover, metabolomic screening of the secondary bile acids' deoxycholic acid (DCA) and lithocholic acid (LCA) correlated significantly with Lactobacillus reuteri and Lactobacillus amylovorus, but only LCA exerted a protective function in the animal model. In addition, LCA supplementation altered the distribution of intestinal T-cell populations and resulted in significantly enriched CD8+ CTLs, and in vivo and in vitro experiments showed that LCA increased SLA-I expression in porcine intestinal epithelial cells via FXR receptors, thereby recruiting CD8+ CTLs to exert antiviral effects. CONCLUSIONS: Overall, our findings indicate that the diversity of gut microbiota influences the development of the disease, and manipulating Lactobacillus reuteri and Lactobacillus amylovorus, as well as LCA, represents a promising strategy to improve PEDV infection in piglets. Video Abstract.

Intratumoural microbiota: a new frontier in cancer development and therapy.

Human microorganisms, including bacteria, fungi, and viruses, play key roles in several physiological and pathological processes. Some studies discovered that tumour tissues once considered sterile actually host a variety of microorganisms, which have been confirmed to be closely related to oncogenesis. The concept of intratumoural microbiota was subsequently proposed. Microbiota could colonise tumour tissues through mucosal destruction, adjacent tissue migration, and hematogenic invasion and affect the biological behaviour of tumours as an important part of the tumour microenvironment. Mechanistic studies have demonstrated that intratumoural microbiota potentially promote the initiation and progression of tumours by inducing genomic instability and mutations, affecting epigenetic modifications, promoting inflammation response, avoiding immune destruction, regulating metabolism, and activating invasion and metastasis. Since more comprehensive and profound insights about intratumoral microbiota are continuously emerging, new methods for the early diagnosis and prognostic assessment of cancer patients have been under examination. In addition, interventions based on intratumoural microbiota show great potential to open a new chapter in antitumour therapy, especially immunotherapy, although there are some inevitable challenges. Here, we aim to provide an extensive review of the concept, development history, potential sources, heterogeneity, and carcinogenic mechanisms of intratumoural microorganisms, explore the potential role of microorganisms in tumour prognosis, and discuss current antitumour treatment regimens that target intratumoural microorganisms and the research prospects and limitations in this field.

Lycium barbarum polysaccharide promotes the immunoprotective effects of a recombinant Lactobacillus plantarum vaccine expressing the Trichinella spiralis cathepsin F-like protease 1 gene.

Trichinellosis caused by Trichinella spiralis (T. spiralis) is a zoonotic disease that poses a substantial risk to human health. At present, vaccines used to prevent trichinellosis are effective, but the production of antibody levels and immunogenicity are low. Adjuvants can increase antibody levels and vaccine immunogenicity. As a result, it is critical to develop an effective adjuvant for the T. spiralis vaccine. Recent research has shown that traditional Chinese medicine polysaccharides with low-toxicity and biodegradability can act as adjuvants in vaccines. In this study, BALB/c mice were orally inoculated with a recombinant Lactobacillus plantarum (L. plantarum) vaccine expressing the T. spiralis cathepsin F-like protease 1 gene (rTs-CPF1), which was given three times at 10-day intervals. Lycium barbarum polysaccharide (LBP) was administered orally for 37 days. At 37 days after the first immunization, mice were infected with 350 T. spiralis muscle larvae (ML). Specific IgG and sIgA antibody levels against the T. spiralis CPF1 protein were increased in mice immunized with rTs-CPF1+LBP compared to those immunized with rTs-CPF1 alone. Furthermore, LBP increased IFN-γ and IL-4 expression levels, and the number of intestinal and intramuscular worms was significantly reduced in the rTs-CPF1+LBP group compared to that in the rTs-CPF1 group. In the rTs-CPF1+LBP group, the reduction rates of adult worms and muscle larvae were 47.31 % and 68.88 %, respectively. To summarize, LBP promotes the immunoprotective effects of the T. spiralis vaccine and may be considered as a novel adjuvant in parasitic vaccines.

Single-Cell Transcriptional Analysis of Lamina Propria Lymphocytes in the Jejunum Reveals Innate Lymphoid Cell-like Cells in Pigs.

Pigs are the most suitable model to study various therapeutic strategies and drugs for human beings, although knowledge about cell type-specific transcriptomes and heterogeneity is poorly available. Through single-cell RNA sequencing and flow cytometry analysis of the types in the jejunum of pigs, we found that innate lymphoid cells (ILCs) existed in the lamina propria lymphocytes (LPLs) of the jejunum. Then, through flow sorting of live/dead-lineage (Lin)-CD45+ cells and single-cell RNA sequencing, we found that ILCs in the porcine jejunum were mainly ILC3s, with a small number of NK cells, ILC1s, and ILC2s. ILCs coexpressed IL-7Rα, ID2, and other genes and differentially expressed RORC, GATA3, and other genes but did not express the CD3 gene. ILC3s can be divided into four subgroups, and genes such as CXCL8, CXCL2, IL-22, IL-17, and NCR2 are differentially expressed. To further detect and identify ILC3s, we verified the classification of ILCs in the porcine jejunum subgroup and the expression of related hallmark genes at the protein level by flow cytometry. For systematically characterizing ILCs in the porcine intestines, we combined our pig ILC dataset with publicly available human and mice ILC data and identified that the human and pig ILCs shared more common features than did those mouse ILCs in gene signatures and cell states. Our results showed in detail for the first time (to our knowledge) the gene expression of porcine jejunal ILCs, the subtype classification of ILCs, and the markers of various ILCs, which provide a basis for an in-depth exploration of porcine intestinal mucosal immunity.

A novel "prime and pull" strategy mediated by the combination of two dendritic cell-targeting designs induced protective lung tissue-resident memory T cells against H1N1 influenza virus challenge.

Vaccination is still the most promising strategy for combating influenza virus pandemics. However, the highly variable characteristics of influenza virus make it difficult to develop antibody-based universal vaccines, until now. Lung tissue-resident memory T cells (TRM), which actively survey tissues for signs of infection and react rapidly to eliminate infected cells without the need for a systemic immune reaction, have recently drawn increasing attention towards the development of a universal influenza vaccine. We previously designed a sequential immunization strategy based on orally administered Salmonella vectored vaccine candidates. To further improve our vaccine design, in this study, we used two different dendritic cell (DC)-targeting strategies, including a single chain variable fragment (scFv) targeting the surface marker DC-CD11c and DC targeting peptide 3 (DCpep3). Oral immunization with Salmonella harboring plasmid pYL230 (S230), which displayed scFv-CD11c on the bacterial surface, induced dramatic production of spleen effector memory T cells (TEM). On the other hand, intranasal boost immunization using purified DCpep3-decorated 3M2e-ferritin nanoparticles in mice orally immunized twice with S230 (S230inDC) significantly stimulated the differentiation of lung CD11b+ DCs, increased intracellular IL-17 production in lung CD4+ T cells and elevated chemokine production in lung sections, such as CXCL13 and CXCL15, as determined by RNAseq and qRT‒PCR assays, resulting in significantly increased percentages of lung TRMs, which could provide efficient protection against influenza virus challenge. The dual DC targeting strategy, together with the sequential immunization approach described in this study, provides us with a novel "prime and pull" strategy for addressing the production of protective TRM cells in vaccine design.

Chicken dendritic cell-targeting nanobodies mediated improved protective effects against H9N2 influenza virus challenge in a homologous sequential immunization study.

Global poultry production is still severely affected by H9N2 avian influenza virus (AIV), and the development of a novel universal AIV vaccine is still urgently needed. Neuraminidase (NA) has recently been shown to be an efficient conserved protective antigen. In this study, we fused the extracellular region of the NA gene with a ferritin cassette (pYL281), which resulted in self-assembled 24-mer nanoparticles with the NA protein displayed outside the nanoparticles. In addition, a chicken dendritic cell-targeting nanobody-phage74 was also inserted ahead of the NA protein to yield pYL294. Incubation with chicken bone marrow-derived dendritic cells (chBMDCs) showed that the DC-targeting nanoparticles purified from the pYL294 strain significantly increased the maturation of chBMDCs, as shown by increased levels of CCL5, CCR7, CD83 and CD86 compared with nontargeting proteins. Then, a chicken study was performed using Salmonella oral administration together with intranasal boost with purified proteins. Compared with the other groups, oral immunization with Salmonella harboring pYL294 followed by intranasal boost with purified DC-targeting nanoparticles dramatically increased the humoral IgY and mucosal IgA antibody response, as well as increased the cellular immune response, as shown by elevated splenic lymphocyte proliferation and intracellular mRNA levels of IL-4 and IFN-γ. Finally, sequential immunization with DC-targeting nanoparticles showed increased protection against G57 subtype H9N2 virus challenge compared with other groups, as shown by significantly decreased virus RNA copy numbers in oropharyngeal washes (Days 3, 5 and 7 post challenge) and cloacal washes (Day 7), significantly decreased lung virus titers on Day 5 post challenge and increased body weight gains during the challenge.

Lactobacillus Plantarum NC8 and its metabolite acetate alleviate type 1 diabetes via inhibiting NLRP3.

A healthy organism is the result of host-microbiome co-evolution. Microbial metabolites can also stimulate immune cells to reduce intestinal inflammation and permeability. Gut dysbiosis will lead to a variety of autoimmune diseases, such as Type 1 diabetes (T1D). Most of probiotics, such as Lactobacillus casei, Lactobacillus reuteri, Bifidobacterium bifidium, and Streptococcus thermophiles, can improve the intestinal flora structure of the host, reduce intestinal permeability, and relieve symptoms of T1D patients if ingested above probiotics in sufficient amounts. Lactobacillus Plantarum NC8, a kind of Lactobacillus, whether it has an effect on T1D, and the mechanism of it regulating T1D is still unclear. As a member of the inflammatory family, NLRP3 inflammasome can enhance inflammatory responses by promoting the production and secretion of proinflammatory cytokines. Many previous studies had shown that NLRP3 also plays an important role in the development of T1D. When the NLRP3 gene is deleted, the disease progression of T1D will be delayed. Therefore, this study investigated whether Lactobacillus Plantarum NC8 can alleviate T1D by regulating NLRP3. The results demonstrated that Lactobacillus Plantarum NC8 and its metabolites acetate play a role in T1D by co-modulating NLRP3. Lactobacillus Plantarum NC8 and acetate can reduce the damage of T1D in the model mice, even if orally administered them in the early stage of T1D. The number of Th1/Th17 cells in the spleen and pancreatic lymph nodes (PLNs) of T1D mice were significantly reduced by oral Lactobacillus Plantarum NC8 or acetate. The expression of NLRP3 in the pancreas of T1D mice or murine macrophages of inflammatory model were significantly inhibited by treatment with Lactobacillus Plantarum NC8 or acetate. In addition, the number of macrophages in the pancreas were significantly reduced by the treatment with Lactobacillus Plantarum NC8 or acetate. In summary, this study indicated that the regulatory mechanism of Lactobacillus Plantarum NC8 and its metabolite acetate to T1D maybe via inhibiting NLRP3 and provides a novel insights into the mechanism of the alleviated role of probiotics to T1D.

Lactobacillus plantarum surface-displayed Eimeria tenella profilin antigens with FliC flagellin elicit protection against coccidiosis in chickens.

Coccidiosis is a parasitic disease in the intestine caused by the genus Eimeria that poses a substantial economic threat to the broiler breeding industry. The misuse of chemoprophylaxis and live oocyst vaccines has a negative impact on chicken reproductivity. Therefore, there is a pressing need to develop safe, convenient, and effective vaccines. Lactic acid bacteria can be used as a means to deliver mucosal vaccines against intestinal pathogens, which is a promising strategy. In this study, a recombinant Lactobacillus plantarum (L. plantarum) with surface-expressed antigens constructed from the fusion of Eimeria tenella (E. tenella) antigen profilin and the Salmonella enterica serovar Typhimurium flagellin protein FliC was created. After oral immunization with the recombinant L. plantarum, T-cell differentiation was analyzed by flow cytometry, and specific antibody levels were determined via indirect ELISA. Oocyst shedding, body weight, and cecum lesions were assessed as measures of protective immunity after challenge with E. tenella. The results of this study demonstrate the effectiveness of recombinant L. plantarum as an immunization agent for chickens. Specific IgA titers in the intestine and specific IgG antibody titers in the serum were significantly higher in chickens immunized with recombinant L. plantarum (P < 0.001). Additionally, the levels of IL-2 (P < 0.05) and IFN-γ (P < 0.01) in the serum were markedly increased. Recombinant L. plantarum induced T-cell differentiation, resulting in a higher proportion of CD4+ and CD8+ T cells in splenocytes (P < 0.001). Fecal oocyst shedding in the immunized group was significantly reduced (P < 0.001). Additionally, recombinant L. plantarum significantly relieved pathological damage in the cecum, as evidenced by lesion scores (P < 0.01) and histopathological cecum sections. In conclusion, the present study provides evidence to support the possibility of using L. plantarum as a promising carrier for the delivery of protective antigens to effectively protect chickens against coccidiosis.

Treatment of pregnant mice with ABZ had no effect on the immune response of their offspring infected with Trichinella spiralis.

Trichinellosis is a food-borne parasitic disease with a worldwide distribution that not only endangers human health but also leads to economic loss. Infection of pregnant animals with Trichinella spiralis (T. spiralis) may lead to abortion and other adverse consequences, so it is necessary to treat the infection during pregnancy. Albendazole (ABZ) is an effective therapeutic drug for adult T. spiralis worms. The safety of this drug during pregnancy, especially whether it has any effect on offspring, should be fully evaluated. A change in the immune response to T. spiralis in the offspring of pregnant mice treated with ABZ may lead to a difference in susceptibility to T. spiralis compared to that of the offspring of normal mice. However, the safety of ABZ treatment in pregnant mice and the effects on the immune response and susceptibility of their offspring to T. spiralis are poorly understood. Therefore, we assessed whether maternal ABZ treatment during pregnancy affects the immune response or susceptibility to T. spiralis in infected offspring. In this study, mice were infected with T. spiralis at 10 days of pregnancy and treated with ABZ at 3 days post infection (dpi), and the specific immune response in the pregnant mice and the survival rate and worm burden of their 6-week-old offspring after T. spiralis infection were examined. The results showed that the antiparasitic immune response in pregnant mice was activated by T. spiralis infection. Treatment of pregnant mice with ABZ increased the percentage of CD4 + T cells. The percentages of Th2 and Treg cells in the PP, MLN and spleen of pregnant mice in the infection group were significantly increased compared with those of normal mice. ABZ treatment during pregnancy promoted the Th2 and Treg immune responses in pregnant mice infected with T. spiralis. The transcriptional levels of the Th2 and Treg cytokines IL-4, IL-5, IL-13, and TGF-ß in the small intestine, MLN and spleen of pregnant mice in the treatment group were significantly higher than those of pregnant mice in the T. spiralis infection only group. The results indicated that ABZ treatment did not cause abortion in pregnant mice or affect the survival rate of their offspring. Furthermore, treatment of pregnant mice with ABZ had no significant effect on the above immune responses in their T. spiralis-infected offspring compared to those of T. spiralis-infected offspring of mice in the normal group. The results also indicated that treatment of pregnant mice infected with T. spiralis with ABZ shifted the immune response to a Th2- and Treg-skewed immune response and that this drug had no effects on the offspring survival rate, immune response or worm burden after T. spiralis infection. This study further indicated that ABZ administration to treat T. spiralis infection in pregnant mice is safe for the select immune response and susceptibility of their offspring.

Protection against genotype VII Newcastle disease virus by a mucosal subunit vaccination based on bacterium-like particles bearing the F or HN antigen.

Genotype VII Newcastle disease viruses (NDV) are still epidemic in many countries in chicken and waterfowl despite intensive vaccination with conventional live and inactivated vaccines. Here, we developed an effective mucosal subunit vaccine based on a bacterium-like particles (BLPs) delivery platform derived from Lactococcus lactis. The NDV protective antigen F or HN fused protein anchor (PA) was expressed by recombinant baculovirus and loaded on the surface of BLPs, resulting in BLPs-F and BLPs-HN, respectively. Efficient uptake of BLPs-F/HN by antigen-presenting cells activated the innate immune system depending mainly on the combination of chicken TLR2 type 1 (chTLR2t1) and chicken TLR1 type 1 (chTLR1t1) was observed. Delivered intranasally, BLPs-F, BLPs-HN, or BLPs-F/HN (a mixture containing equal amounts of BLPs-F and BLPs-HN) elicited robust local NDV-specific SIgA in the trachea as well as systemic neutralizing antibody and a mixed Th1/Th2 immune response in chickens. Notably, BLPs-F/HN provided as high as 90 % protection rate against intranasal challenge with a lethal dose of virulent genotype VII NDV NA-1 strain. These data indicate that this BLP-based subunit vaccine has the potential to be a novel mucosal vaccine against genotype VII NDV infection.

Homologous Sequential Immunization Using Salmonella Oral Administration Followed by an Intranasal Boost with Ferritin-Based Nanoparticles Enhanced the Humoral Immune Response against H1N1 Influenza Virus.

The influenza virus continues to pose a great threat to public health due to the frequent variations in RNA viruses. Vaccines targeting conserved epitopes, such as the extracellular domain of the transmembrane protein M2 (M2e), a nucleoprotein, and the stem region of hemagglutinin proteins, have been developed, but more efficient strategies, such as nanoparticle-based vaccines, are still urgently needed. However, the labor-intensive in vitro purification of nanoparticles is still necessary, which could hinder the application of nanoparticles in the veterinary field in the future. To overcome this limitation, we used regulated lysis Salmonella as an oral vector with which to deliver three copies of M2e (3M2e-H1N1)-ferritin nanoparticles in situ and evaluated the immune response. Then, sequential immunization using Salmonella-delivered nanoparticles followed by an intranasal boost with purified nanoparticles was performed to further improve the efficiency. Compared with 3M2e monomer administration, Salmonella-delivered in situ nanoparticles significantly increased the cellular immune response. Additionally, the results of sequential immunization showed that the intranasal boost with purified nanoparticles dramatically stimulated the activation of lung CD11b dendritic cells (DCs) and elevated the levels of effector memory T (TEM) cells in both spleen and lung tissues as well as those of CD4 and CD8 tissue-resident memory T (TRM) cells in the lungs. The increased production of mucosal IgG and IgA antibody titers was also observed, resulting in further improvements to protection against a virus challenge, compared with the pure oral immunization group. Salmonella-delivered in situ nanoparticles efficiently increased the cellular immune response, compared with the monomer, and sequential immunization further improved the systemic immune response, as shown by the activation of DCs, the production of TEM cells and TRM cells, and the mucosal immune response, thereby providing us with a novel strategy by which to apply nanoparticle-based vaccines in the future. IMPORTANCE Salmonella-delivered in situ nanoparticle platforms may provide novel nanoparticle vaccines for oral administration, which would be beneficial for veterinary applications. The combination of administering Salmonella-vectored, self-assembled nanoparticles and an intranasal boost with purified nanoparticles significantly increased the production of effector memory T cells and lung resident memory T cells, thereby providing partial protection against an influenza virus challenge. This novel strategy could open a novel avenue for the application of nanoparticle vaccines for veterinary purposes.

NLRP3 Plays a Key Role in Antihelminth Immunity in the Enteral and Parenteral Stages of Trichinella spiralis-Infected Mice.

Trichinellosis is an important foodborne zoonosis, and no effective treatments are yet available. Nod-like receptor (NLR) plays a critical role in the host response against nematodes. Therefore, we aimed to explore the role of the NLRP3 inflammasome (NLRP3) during the adult, migrating, and encysted stages of Trichinella spiralis infection. The mice were treated with the specific NLRP3 inhibitor MCC950 after inoculation with T. spiralis. Then, the role that NLRP3 plays during T. spiralis infection of mice was evaluated using enzyme-linked immunosorbent assay (ELISA), Western blotting, flow cytometry, histopathological evaluation, bone marrow-derived macrophage (BMDM) stimulation, and immunofluorescence. The in vivo results showed that NLRP3 enhanced the Th1 immune response in the adult and migrating stages and weakened the Th2 immune response in the encysted stage. NLRP3 promoted the release of proinflammatory factors (interferon gamma [IFN-γ]) and suppressed the release of anti-inflammatory factors (interleukin 4 [IL-4]). Pathological changes were also improved in the absence of NLRP3 in mice during T. spiralis infection. Importantly, a significant reduction in adult worm burden and muscle larvae burden at 7 and 35 days postinfection was observed in mice treated with the specific NLRP3 inhibitor MCC950. In vitro, we first demonstrated that NLRP3 in macrophages can be activated by T. spiralis proteins and promotes IL-1ß and IL-18 release. This study revealed that NLRP3 is involved in the host response to T. spiralis infection and that targeted inhibition of NLRP3 enhanced the Th2 response and accelerated T. spiralis expulsion. These findings may help in the development of protocols for controlling trichinellosis.