Microbiota-derived acetate is associated with functionally optimal virus-specific CD8+ T cell responses to influenza virus infection via GPR43-dependent metabolic reprogramming.

The microbiota-associated factors that affect host susceptibility and adaptive immunity to influenza A virus (IAV) infection have not been fully elucidated. By comparing the microbiota composition between survivors and mice that succumbed to IAV strain PR8 infection, we identified that the commensal bacterium Blautia coccoides protects antibiotics (Abx)-treated or germ-free (GF) mice from PR8 infection by inducing functionally optimal virus-specific CD8+ T cell responses. Administration of exogenous acetate reproduced the protective effect of B. coccoides monocolonization in Abx and GF mice, enhancing oxidative phosphorylation and glycolysis as well as secretion of IFN-γ and granzyme B in virus-specific CD8+ T cells, dependent on GPR43 signaling and acetyl-CoA synthetase 2. Thus, we have demonstrated that microbiota-derived acetate possesses an antiviral effect that induces an optimal virus-specific CD8+ T cell response to IAV PR8 infection via GPR43-dependent metabolic reprogramming.

Eimeria tenella rhoptry neck protein 2 plays a key role in the process of invading the host intestinal epithelium.

The Apicomplexa parasitic phylum rhoptry neck protein 2 (RON2) plays a key role in the process of invading host cells. Eimeria tenella, an intracellular protozoan shares a similar conserved invasion pattern. However, whether E. tenella RON2 participates in the process of invading the host intestinal epithelium is poorly understood. In this study, the sequence of EtRON2 was analyzed and expressed. The expression of the truncated extracellular N-terminal fragment of EtRON2 (403-700 aa, designated EtRON2403-700) with a molecular mass of 38.3 kDa. EtRON2 in the sporozoite protein was detected at 151.4 kDa by rabbit anti-rEtRON2403-700 antibody. Immunofluorescence results showed that EtRON2 was mainly localized to the nucleus and apex of the E. tenella sporozoite. qPCR results showed that the highest expression level of EtRON2 was detected in sporulated oocysts compared with other developmental stages of E. tenella. In vitro invasion inhibition assays showed that the capacity of sporozoites to invade DF-1 cells was significantly inhibited after pretreatment with the rabbit anti-rEtRON2403-700 antibody. Silencing the EtRON2 gene by RNA interference (RNAi) significantly inhibited EtRON2 expression and significantly reduced the invasion of DF-1 cells by sporozoites. In vivo experiments revealed a significant decrease parasite burden and oocyst outputs in chicks after infection with EtRON2 gene-silenced sporozoites by cloacal inoculation. Recombinant EtRON2403-700 (rEtRON2403-700) immunizes chicks effectively against E. tenella infection by inducing humoral immunity and upregulating IFN-γ and CD8+ T lymphocytes. Furthermore, chicks exhibited increased relative weight gain rates, lower cecum lesion scores, and reduced oocyst outputs during the E. tenella challenge. H&E staining showed that the cecum tissue of chicks immunized with rEtRON2403-700 showed relatively mild histopathological changes. In conclusion, the results of this study demonstrated that EtRON2 plays a key role in E. tenella invasion of the host intestinal epithelium and provides a potential target for vaccines against E. tenella infection.

Immunoprotective effect of recombinant Lactobacillus plantarum expressing largemouth bass virus MCP on largemouth bass.

Largemouth bass virus (LMBV) is an infectious pathogen that causes high mortality rates in largemouth bass, and outbreaks of this virus can significantly harm the aquaculture industry. Currently, no vaccine has been developed that can effectively prevent the transmission of LMBV. In this study, we constructed a recombinant Lactobacillus plantarum (L. plantarum) strain capable of expressing the MCP gene of LMBV and displaying this protein on its surface; then, we evaluated the immunoprotective effect of this recombinant bacterium on largemouth bass. Western blotting, immunofluorescence, and flow cytometry confirmed that MCP was successfully expressed and anchored on the surfaces of NC8 cells. Immunization of largemouth bass with NC8-pSIP409-pgsA'-MCP via the oral feeding route induced CD4, CD8, IL-1ß, and IL-6 gene expression. In addition, NC8-pSIP409-pgsA'-MCP at different CFUs increased the survival of largemouth bass after LMBV infection; in particular, NC8-pSIP409-pgsA'-MCP (109 CFU) resulted in approximately 30% survival. NC8-pSIP409-pgsA'-MCP immunization alleviated the pathological changes in the liver and spleen, exerting a more advantageous protective effect. These data suggest that the recombinant L. plantarum strain NC8-pSIP409-pgsA'-MCP can increase the resistance of largemouth bass to LMBV infection and that this strain is a promising candidate oral vaccine for the prevention of LMBV infection.

LysoPE mediated by respiratory microorganism Aeromicrobium camelliae alleviates H9N2 challenge in mice.

Influenza remains a severe respiratory illness that poses significant global health threats. Recent studies have identified distinct microbial communities within the respiratory tract, from nostrils to alveoli. This research explores specific anti-influenza respiratory microbes using a mouse model supported by 16S rDNA sequencing and untargeted metabolomics. The study found that transferring respiratory microbes from mice that survived H9N2 influenza to antibiotic-treated mice enhanced infection resistance. Notably, the levels of Aeromicrobium were significantly higher in the surviving mice. Mice pre-treated with antibiotics and then inoculated with Aeromicrobium camelliae showed reduced infection severity, as evidenced by decreased weight loss, higher survival rates, and lower lung viral titres. Metabolomic analysis revealed elevated LysoPE (16:0) levels in mildly infected mice. In vivo and in vitro experiments indicated that LysoPE (16:0) suppresses inducible nitric oxide synthase (INOS) and cyclooxygenase-2 (COX2) expression, enhancing anti-influenza defences. Our findings suggest that Aeromicrobium camelliae could serve as a potential agent for influenza prevention and a prognostic marker for influenza outcomes.

The E3 ligase ASB3 downregulates antiviral innate immunity by targeting MAVS for ubiquitin-proteasomal degradation.

E3 ubiquitin ligases are very important for regulating antiviral immunity during viral infection. Here, we discovered that Ankyrin repeat and SOCS box-containing protein 3 (ASB3), an E3 ligase, are upregulated in the presence of RNA viruses, particularly influenza A virus (IAV). Notably, overexpression of ASB3 inhibits type I IFN (IFN-I) responses induced by Sendai virus (SeV) and IAV, and ablation of ASB3 restores SeV and H9N2 infection-mediated transcription of IFN-ß and its downstream interferon-stimulated genes (ISGs). Interestingly, animals lacking ASB3 presented decreased susceptibility to H9N2 and H1N1 infections. Mechanistically, ASB3 interacts with MAVS and directly mediates K48-linked polyubiquitination and degradation of MAVS at K297, thereby inhibiting the phosphorylation of TBK1 and IRF3 and downregulating downstream antiviral signaling. These findings establish ASB3 as a critical negative regulator that controls the activation of antiviral signaling and describe a novel function of ASB3 that has not been previously reported.

TLR3/TRIF and MAVS Signaling Is Essential in Regulating Mucosal T Cell Responses during Rotavirus Infection.

The functions of the natural dsRNA sensors TLR3 (TRIF) and RIG-I (MAVS) are crucial during viral challenge and have not been accurately clarified in adaptive immune responses to rotavirus (RV) infection. In this study, we found that RV infection caused severe pathological damage to the small intestine of TLR3-/- and TRIF-/- mice. Our data found that dendritic cells from TLR3-/- and TRIF-/- mice had impaired Ag presentation to the RV and attenuated initiation of T cells upon viral infection. These attenuated functions resulted in impaired CD4+ T and CD8+ T function in mice lacking TLR3-TRIF signaling postinfection. Additionally, attenuated proliferative capacity of T cells from TLR3-/- and TRIF-/- mice was observed. Subsequently, we observed a significant reduction in the absolute number of memory T cells in the spleen and mesenteric lymph node (MLN) of TRIF-/- recipient mice following RV infection in a bone marrow chimeric model. Furthermore, there was reduced migration of type 2 classical dendritic cells from the intestine to MLNs after RV infection in TLR3-/- and TRIF-/- mice. Notably, RV infection resulted in attenuated killing of spleen and MLN tissues in TRIF-/- and MAVS-/- mice. Finally, we demonstrated that RV infection promoted apoptosis of CD8+ T cells in TRIF-/- and TLR3-/-MAVS-/- mice. Taken together, our findings highlight an important mechanism of TLR3 signaling through TRIF in mucosal T cell responses to RV and lay the foundation for the development of a novel vaccine.

CRISPR/Cas13a-based genome editing for establishing the detection method of H9N2 subtype avian influenza virus.

Avian influenza virus (AIV) subtype H9N2 has significantly threatened the poultry business in recent years by having become the predominant subtype in flocks of chickens, ducks, and pigeons. In addition, the public health aspects of H9N2 AIV pose a significant threat to humans. Early and rapid diagnosis of H9N2 AIV is therefore of great importance. In this study, a new method for the detection of H9N2 AIV based on fluorescence intensity was successfully established using CRISPR/Cas13a technology. The Cas13a protein was first expressed in a prokaryotic system and purified using nickel ion affinity chromatography, resulting in a high-purity Cas13a protein. The best RPA (recombinase polymerase amplification) primer pairs and crRNA were designed and screened, successfully constructing the detection of H9N2 AIV based on CRISPR/Cas13a technology. Optimal concentration of Cas13a and crRNA was determined to optimize the constructed assay. The sensitivity of the optimized detection system is excellent, with a minimum detection limit of 10° copies/µL and didn't react with other avian susceptible viruses, with excellent specificity. The detection method provides the basis for the field detection of the H9N2 AIV.

Ligilactobacillus salivarius XP132 with antibacterial and immunomodulatory activities inhibits horizontal and vertical transmission of Salmonella Pullorum in chickens.

Probiotics are increasingly recognized for their capacity to combat pathogenic bacteria. In this study, we isolated a strain of Ligilactobacillus salivarius XP132 from the gut microbiota of healthy chickens. This strain exhibited resistance to low pH and bile salts, auto-aggregation capabilities, and the ability to co-aggregate with pathogenic Salmonella. The in vitro antibacterial activity of Ligilactobacillus salivarius XP132 was tested using an Oxford cup antibacterial test, and the results showed that Ligilactobacillus salivarius XP132 exhibited broad-spectrum antibacterial activity, with especially strong antibacterial activity against Salmonella. In animal experiments with white feather broilers and specific-pathogens-free (SPF) chickens, we orally administered 1 × 109 CFU XP132 live bacteria per chicken per day, and detected the content of Salmonella in the liver, spleen, intestinal contents, and eggs of the chickens by RT-qPCR. Oral administration of Lactobacillus salivarius XP132 group significantly reduced the levels of Salmonella in chicken liver, spleen, intestinal contents and eggs, and the oral administration of Ligilactobacillus salivarius XP132 significantly inhibited the horizontal and vertical transmission of Salmonella in SPF chickens and white-feathered broilers. After oral administration of XP132, the production of chicken serum anti-infective cytokine IFN-γ was also significantly up-regulated, thereby enhancing the host's ability to resist infection. In addition, the production of various serum inflammatory cytokines, including IL-1ß, IL-6, IL-8, and TNF-α, was down-regulated, leading to significant amelioration of the inflammatory response induced by S. Pullorum in chickens. These findings suggest that Ligilactobacillus salivarius XP132 possesses potent antibacterial and immunomodulatory properties that effectively prevent both horizontal and vertical transmission of Salmonella Pullorum, highlighting its potential as a valuable tool for the prevention and control of Salmonella disease.

ASB3 expression aggravates inflammatory bowel disease by targeting TRAF6 protein stability and affecting the intestinal microbiota.

E3 ubiquitin ligase (E3) plays a vital role in regulating inflammatory responses by mediating ubiquitination. Previous studies have shown that ankyrin repeat and SOCS box-containing protein 3 (ASB3) is involved in immunomodulatory functions associated with cancer. However, the impact of ASB3 on the dynamic interplay of microbiota and inflammatory responses in inflammatory bowel disease (IBD) is unclear. Here, we systematically identify the E3 ligase ASB3 as a facilitative regulator in the development and progression of IBD. We observed that ASB3 exhibited significant upregulation in the lesions of patients with IBD. ASB3-/- mice are resistant to dextran sodium sulfate-induced colitis. IκBα phosphorylation levels and production of proinflammatory factors IL-1ß, IL-6, and TNF-α were reduced in the colonic tissues of ASB3-/- mice compared to WT mice. This colitis-resistant phenotype was suppressed after coprophagic microbial transfer and reversed after combined antibiotics removed the gut commensal microbiome. Mechanistically, ASB3 specifically catalyzes K48-linked polyubiquitination of TRAF6 in intestinal epithelial cells. In contrast, in ASB3-deficient organoids, the integrity of the TRAF6 protein is shielded, consequently decelerating the onset of intestinal inflammation. ASB3 is associated with dysregulation of the colitis microbiota and promotes proinflammatory factors' production by disrupting TRAF6 stability. Strategies to limit the protein level of ASB3 in intestinal epithelial cells may help in the treatment of colitis. IMPORTANCE: Ubiquitination is a key process that controls protein stability. We determined the ubiquitination of TRAF6 by ASB3 in intestinal epithelial cells during colonic inflammation. Inflammatory bowel disease patients exhibit upregulated ASB3 expression at focal sites, supporting the involvement of degradation of TRAF6, which promotes TLR-Myd88/TRIF-independent NF-κB aberrant activation and intestinal microbiota imbalance. Sustained inflammatory signaling in intestinal epithelial cells and dysregulated protective probiotic immune responses mediated by ASB3 collectively contribute to the exacerbation of inflammatory bowel disease. These findings provide insights into the pathogenesis of inflammatory bowel disease and suggest a novel mechanism by which ASB3 increases the risk of colitis. Our results suggest that future inhibition of ASB3 in intestinal epithelial cells may be a novel clinical strategy.

AhR ligands from LGG metabolites promote piglet intestinal ILC3 activation and IL-22 secretion to inhibit PEDV infection.

In maintaining organismal homeostasis, gut immunity plays a crucial role. The coordination between the microbiota and the immune system through bidirectional interactions regulates the impact of microorganisms on the host. Our research focused on understanding the relationships between substantial changes in jejunal intestinal flora and metabolites and intestinal immunity during porcine epidemic diarrhea virus (PEDV) infection in piglets. We discovered that Lactobacillus rhamnosus GG (LGG) could effectively prevent PEDV infection in piglets. Further investigation revealed that LGG metabolites interact with type 3 innate lymphoid cells (ILC3s) in the jejunum of piglets through the aryl hydrocarbon receptor (AhR). This interaction promotes the activation of ILC3s and the production of interleukin-22 (IL-22). Subsequently, IL-22 facilitates the proliferation of IPEC-J2 cells and activates the STAT3 signaling pathway, thereby preventing PEDV infection. Moreover, the AhR receptor influences various cell types within organoids, including intestinal stem cells (ISCs), Paneth cells, and enterocytes, to promote their growth and development, suggesting that AhR has a broad impact on intestinal health. In conclusion, our study demonstrated the ability of LGG to modulate intestinal immunity and effectively prevent PEDV infection in piglets. These findings highlight the potential application of LGG as a preventive measure against viral infections in livestock.IMPORTANCEWe observed high expression of the AhR receptor on pig and human ILC3s, although its expression was negligible in mouse ILC3s. ILC3s are closely related to the gut microbiota, particularly the secretion of IL-22 stimulated by microbial signals, which plays a crucial regulatory role in intestinal immunity. In our study, we found that metabolites produced by beneficial gut bacteria interact with ILC3s through AhR, thereby maintaining intestinal immune homeostasis in pigs. Moreover, LGG feeding can enhance the activation of ILC3s and promote IL-22 secretion in the intestines of piglets, ultimately preventing PEDV infection.

Bacillus halotolerans attenuates inflammation induced by enterotoxigenic Escherichia coli infection in vivo and in vitro based on its metabolite soyasaponin I regulating the p105-Tpl2-ERK pathway.

Soyasaponins, recognized for their anti-inflammatory and antioxidant effects, have not yet been fully explored for their role in combating enterotoxigenic Escherichia coli (ETEC) infections. Recent findings identified them in small-molecule metabolites of Bacillus, suggesting their broader biological relevance. This research screened 88 strains of B. halotolerans, identifying the strain BH M20221856 as significantly inhibitory against ETEC growth in vitro. It also reduced cellular damage and inflammatory response in IPEC-J2 cells. The antimicrobial activity of BH M20221856 was attributed to its small-molecule metabolites rather than secretory proteins. A total of 69 small molecules were identified from the metabolites of BH M20221856 using liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS). Among these, soyasaponin I (SoSa I) represented the largest multiple change in the enrichment analysis of differential metabolites and exhibited potent anti-ETEC effects in vivo. It significantly reduced the bacterial load of E. coli in mouse intestines, decreased serum endotoxin, D-lactic acid, and oxidative stress levels and alleviated intestinal pathological damage and inflammation. SoSa I enhanced immune regulation by mediating the p105-Tpl2-ERK signaling pathway. Further evaluations using transepithelial electrical resistance (TEER) and cell permeability assays showed that SoSa I alleviated ETEC-induced damage to epithelial barrier function. These results suggest that BH M20221856 and SoSa I may serve as preventative biologics against ETEC infections, providing new insights for developing strategies to prevent and control this disease.

Oral vaccination with a recombinant Lactobacillus plantarum expressing the Eimeria tenella rhoptry neck 2 protein elicits protective immunity in broiler chickens infected with Eimeria tenella.

BACKGROUND: Chicken coccidiosis is a protozoan disease that leads to considerable economic losses in the poultry industry. Live oocyst vaccination is currently the most effective measure for the prevention of coccidiosis. However, it provides limited protection with several drawbacks, such as poor immunological protection and potential reversion to virulence. Therefore, the development of effective and safe vaccines against chicken coccidiosis is still urgently needed. METHODS: In this study, a novel oral vaccine against Eimeria tenella was developed by constructing a recombinant Lactobacillus plantarum (NC8) strain expressing the E. tenella RON2 protein. We administered recombinant L. plantarum orally at 3, 4 and 5 days of age and again at 17, 18 and 19 days of age. Meanwhile, each chick in the commercial vaccine group was immunized with 3 × 102 live oocysts of coccidia. A total of 5 × 104 sporulated oocysts of E. tenella were inoculated in each chicken at 30 days. Then, the immunoprotection effect was evaluated after E. tenella infection. RESULTS: The results showed that the proportion of CD4+ and CD8+ T cells, the proliferative ability of spleen lymphocytes, inflammatory cytokine levels and specific antibody titers of chicks immunized with recombinant L. plantarum were significantly increased (P < 0.05). The relative body weight gains were increased and the number of oocysts per gram (OPG) was decreased after E. tenella challenge. Moreover, the lesion scores and histopathological cecum sections showed that recombinant L. plantarum can significantly relieve pathological damage in the cecum. The ACI was 170.89 in the recombinant L. plantarum group, which was higher than the 150.14 in the commercial vaccine group. CONCLUSIONS: These above results indicate that L. plantarum expressing RON2 improved humoral and cellular immunity and enhanced immunoprotection against E. tenella. The protective efficacy was superior to that of vaccination with the commercial live oocyst vaccine. This study suggests that recombinant L. plantarum expressing the RON2 protein provides a promising strategy for vaccine development against coccidiosis.

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.

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.

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.

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.

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.