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The influenza A (H1N1) virus is a highly contagious acute respiratory disease affecting pigs and humans. This disease causes severe economic loss in many countries, and developing mucosal vaccines is an efficient strategy to control the influenza virus. The neonatal Fc receptor (FcRn) plays an important role in transferring IgG across polarized epithelial cells. In the present study, an oral vaccine was developed using Lactobacillus plantarum to deliver the internal influenza viral protein M2e fused to an IgG Fc fragment. Oral vaccination with recombinant L. plantarum expressing 3M2e-Fc elicited Peyer's patch (PP) DC activation, improved the number of gamma interferon (IFN-γ)-producing T cells and increased the frequency of CD8 + IFN-γ + cells in the mesenteric lymph nodes (MLNs). In addition, the recombinant L . plantarum can induce PP B220 + IgA + expression and enhance specific sIgA secretion and the shaping of growth centers (GCs) in PPs. Furthermore, the data demonstrated that immunization with recombinant L. plantarum expressing 3M2e-Fc markedly reduced the viral load in the lung and protected against H1N1 influenza virus and mouse-adapted H9N2 avian influenza virus (AIV) challenge in BALB/c mice. Collectively, the data also showed that this vaccine strategy provided effective protective immunity against infection with homologous and heterologous influenza viruses in a mouse model and may be useful for future influenza vaccine development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• T. spiralis disrupts gut homeostasis and impairs the development of the intestinal ecosystem. • Ascending mucosal type II immunity is associated with increased gut microbiota diversity. • Beneficial genera such as the Lachnospiraceae NK4A136 group, Ruminococcus 1 and Lactococcus decreased in abundance and proinflammatory bacteria Parabacteroides increased in abundance after T. spiralis infection. Understanding the interaction between the gut microbiota and Trichinella spiralis is of interest for the early diagnosis and development of therapeutics for trichinellosis and to reveal the potential role of microbiota in the mechanism of immunomodulation of this tissue-dwelling helminth. In this study, we utilized 16S rRNA gene sequencing to monitor the dynamics of the microbes in BALB/c mice challenged with T. spiralis. Flow cytometry and ELISA were used to analyze cytokines at the same time. Histopathological analysis of the duodenum was also conducted. We found that microbial perturbations occurred during infection. The abundance of the Lachnospiraceae NK4A136 group, Ruminococcus 1 and Lactococcus decreased. However, the abundance of proinflammatory Parabacteroides increased over time after infection. T. spiralis infection also tended to inhibit IFN-γ production, and promote IL-4 and IL-10 levels. In total, T. spiralis disrupts gut homeostasis and impairs the development of the intestinal ecosystem. Defining the bacterial populations affected by T. spiralis infection might help identify microbial markers for diagnosis of the disease, and the populations could also be further exploited as a novel option to treat T. spiralis infection. [ABSTRACT FROM AUTHOR]

• T.spiralis infection could induce the production of Bregs in mice. • Bregs are an important source of spleen and MLN IL-10 in mice infected with T.spiralis. • IL-10 was mainly secreted by the CD19+CD1dhigh CD5+ B cell subset. • The Bregs phenotype is similar toT2-MZP cells after T.spiralis infection in mice. Regulatory B cells (Bregs), a subset of B lymphocytes discovered in the past few decades, have the capacity to suppress the immune response and dampen inflammation by secreting cytokines (IL-10 and TGF-β). Whether Bregs are involved in Trichinella spiralis infection and the phenotypic characteristics of these cells after infection are still unknown. We investigated the phenotype of and dynamic changes in IL-10-producing Bregs in Trichinella spiralis infection in BALB/c mice. We used multicolour fluorescence immunostaining of microwave-treated paraffin sections to investigate the number of Bregs in T. spiralis infection. Flow cytometry (FCM) was used to determine the frequency of Bregs and related subgroups and cytokines in the spleen and mesenteric lymph nodes (MLNs). High levels of IL-10 were detected in the spleen and MLNs of mice after infection with T. spiralis. Furthermore, the frequencies of IL-10-producing CD19+CD1dhighCD5+ regulatory B cells and CD19+ cells were increased during T. spiralis infection. We also showed that the induced phenotype was similar to that of transitional type 2 marginal zone precursor B cells (T-MZP) cells after T. spiralis infection in mice. This study is the first demonstration of the expansion of Bregs following T. spiralis infection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

During a study of ornithophilous viruses in China, a new densovirus (DNV) was isolated from the lung tissue of Parus major (PmDNV-JL). The complete genome of PmDNV-JL was cloned and sequenced. Five open reading frames (ORFs) were identified in the 5166 nt sequence, on the basis of deduced amino acids. It was further shown that this virus caused cytopathic effects (CPE) in Feline kidney cells. The NS1 gene sequence of PmDNV-JL shares 70–99% nucleotide sequence identity with isolates of the Blattella germanica densovirus (BgDNV) and BgDNV-like virus. Phylogenetic analysis indicated that the predicted amino acid sequences of capsid (VP) and non-structural domain (NS1) of PmDNV-JL clustered with the BgDNV and were similar to BgDNV-HB within the genus Densovirus . [ABSTRACT FROM AUTHOR]

The effects of β-glucans from Coriolus versicolor (CVP), which are extracted from a well-known immune stimulator C. versicolor , have been demonstrated extensively in vitro and in vivo. However, until now, the phagocytic activity has not been elucidated. Hence, the objective of the present study was to identify the antibacterial activity of CVP or CVP-treated macrophages by an analysis of cell cytotoxicity, phagocytic activity, intracellular bacterial survival, macrophage activation, production of nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS) in CVP-treated macrophages using flow cytometry, RT-PCR, a gentamicin protection assay, a Nitric oxide assay and an iNOS enzymatic activity assay. The results indicate that CVP-treated macrophages can phagocytize and kill bacteria, probably due to the production of NO and iNOS. More importantly, CVP-treated macrophages are effective at protecting mice against the challenge of Salmonella typhimurium . The results of this study suggest that the antibacterial effects of CVP are probably caused by the activation of innate immune cells, especially macrophages, because the activated macrophage produces NO, which kills bacteria. These phenomena indicate the possibility of CVP as a potential alternative for antibiotics against resistant bacteria. [ABSTRACT FROM AUTHOR]

Eimeria tenella ( E. tenella ) is the most pathogenic genus in Eimeria and can lead to a huge number of deaths of chickens, causing significant economic losses in the poultry industry worldwide. As a natural alkaloid, sanguinarine has many medicinal effects; to a certain extent, it can replace antibiotics and has good application prospects in veterinary medicine. To evaluate the effect of sanguinarine on sporozoites of E.tenella , we used flow cytometry and immunofluorescence staining to detect reactive oxygen species (ROS), mitochondrial membrane potential (MMP), calcium ion (Ca2+), and caspase-3 activation in E.tenella sporozoites treated with different concentrations of sanguinarine. The results of flow cytometry showed that sanguinarine could inhibit the invasion of sporozoites of E.tenella in vitro (P < 0.05) and increase the reactive oxygen species and calcium ions in the sporozoites (P < 0.05). The results of immunofluorescence staining showed that sanguinarine could decrease the mitochondrial membrane potential of sporozoites. Our analysis suggests that sanguinarine can induce apoptosis of E. tenella sporozoites through reactive oxygen species-mediated reduction of the mitochondrial membrane potential and an increase in calcium ion concentration. It follows that sanguinarine is likely to be a novel type of anticoccidiosis drug with good research and clinical application prospects. [ABSTRACT FROM AUTHOR]

Highlights: [•] A DNA vaccine expressing T. gondii mic13 was constructed and evaluated in Kunming mice. [•] pVAX-TgMIC13 induced significant lymphoproliferation, cytokine production and antibody responses. [•] Immunized mice showed increased survival time (21.3 days) and 57.14% reduction of brain cysts. [•] T. gondii MIC13 is a potential candidate to be included in future vaccines against acute and chronic T. gondii infection. [ABSTRACT FROM AUTHOR]

• Invasive recombinant L. plantarum expressing SS1-IL-4 was constructed. • Invasive L. plantarum induced mucosal immunity and humoral immune responses. • Oral vaccination with invasive L. plantarum could reduce AW and ML burden. • Masseter muscle and intestinal damage were reduced after infected with T. spiralis. Trichinellosis is a foodborne zoonosis caused by Trichinella spiralis (T. spiralis) that not only causes considerable economic losses for the global pig breeding and food industries, but also seriously threats the health of human. Therefore, it is very necessary to develop an effective vaccine to prevent trichinellosis. In this study, the invasive Lactobacillus plantarum (L. plantarum) expressing fibronectin-binding protein A (FnBPA) was served as a live bacterial vector to deliver DNA to the host to produce a novel oral DNA vaccine. Co-expressing T. spiralis SS1 and murine interleukin-4 (mIL-4) of DNA vaccine were constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. At 10 days after the third immunization, the experimental mice were challenged with 350 T. spiralis infective larvae. The results found that the mice orally vaccinated with invasive L. plantarum harboring pValac-SS1/pSIP409-FnBPA not only stimulated the production of anti-SS1-specific IgG, Th1/Th2 cell cytokines, and secreted(s) IgA but also decreased worm burden and intestinal damage. However, the mice inoculated with invasive L. plantarum co-expressing SS1 and mIL-4 (pValac-SS1-IL-4/pSIP409-FnBPA) induced the highest protective immune response against T. spiralis infection. The DNA vaccine delivered by invasive L. plantarum provides a novel idea for the prevention of T. spiralis infection. [ABSTRACT FROM AUTHOR]

• Development a vaccine that oral vaccination with Ts 43 delivered by attenuated Salmonella in murine model. • The vaccine elicited local and systemic concurrent Th1/Th2/Th17 immune responses. • The vaccine induced a strong intestinal mucosal sIgA and serum IgG antibody responses. • The immunization animals exhibited partial protection against T. spiralis infection. A vaccine against Trichinella spiralis infection is urgently needed to interrupt its transmission from domestic animals to humans. However, no vaccine against T. spiralis is currently available. Our previous study demonstrated that the use of the 43-kDa glycoprotein present in excretory-secretory (ES) proteins of muscle larvae (ML) as an intramuscular DNA vaccine led to a 52.1% protection rate against T. spiralis infection. Attenuated Salmonella strains have the advantage of eliciting mucosal immunity, which is important for controlling T. spiralis infections at the intestinal stage and can be provided as vaccines via oral or intranasal routes. Therefore, in this study, complete 43-kDa glycoprotein (Ts 43) sequences of T. spiralis were cloned into the vector pYA3681, and the recombinant plasmid pYA3681- Ts 43 was transformed into the attenuated Salmonella typhimurium strain χ11802. The results showed that oral vaccination of mice with attenuated Salmonella carrying the recombinant plasmid pYA3681- Ts 43 induced an evident elevation of the local intestinal mucosal sIgA and serum IgG antibody responses. The flow cytometry results showed that the percentages of CD4+ T cells and secreted IFN-γ, IL-4, and IL-17A in CD4+ T cells were significantly increased in the spleen and mesenteric lymph node (MLN) lymphocytes of the vaccinated groups. In addition, increased levels of the IFN-γ, IL-4, and IL-17A cytokines were also observed in the serum of the immunized groups. The above immune response results in the immunized groups demonstrated that protective immunity was elicited in this study. Finally, vaccinated mice demonstrated a significant 45.9% reduction in ML burden after infection with T. spiralis. This study demonstrated that oral vaccination with Ts 43 delivered by attenuated Salmonella elicited local and systemic concurrent Th1/Th2/Th17 immune responses and provided partial protection against T. spiralis infection in BALB/c mice. This is a prospective strategy for the prevention and control of trichinellosis. [ABSTRACT FROM AUTHOR]

• Invasive Lactobacillus plantarum expressing TsCPF1-IL-4 was constructed. • Invasive L. plantarum induced mucosal immunity and humoral immune responses. • Oral vaccination with invasive L. plantarum could reduce worm burden. • Histopathological damage was reduced after infected with Trichinella spiralis. Trichinellosis is a very important food-borne parasitic disease, that seriously endangers animal husbandry and food safety. Therefore, it is necessary to develop a safe and effective vaccine against Trichinella spiralis infection. In this experiment, invasive Lactobacillus plantarum carrying the FnBPA gene served as a live bacterial vector to deliver nucleic acids to the host to produce a novel oral nucleic acid vaccine. Coexpression of the T. spiralis cathepsin F-like protease 1 gene (TsCPF1) and murine IL-4 (mIL-4) by the nucleic acid vaccine was constructed and subsequently delivered to intestinal epithelial cells via invasive L. plantarum. Thirty-seven days after the first immunization, the experimental mice were challenged with 350 T. spiralis infective larvae by oral gavage. The results showed that mice orally immune-stimulated with invasive L. plantarum pValac-TsCPF1/pSIP409-FnBPA not only produce anti-TsCPF1-specific IgG antibodies, sIgA, Th1/Th2 cytokine distinctly increased but also intestinal damage and worm burden relieved compare to non-invasive TsCPF1 group (pValac-TsCPF1/pSIP409). Most notably, experimental mice immunized with invasive L. plantarum coexpressing TsCPF1 and mIL-4 (pValac-TsCPF1-IL-4/pSIP409-FnBPA) exhibited the highest protection efficiency against T. spiralis infection. The above results reveal that invasive L. plantarum -expressing the FnBPA protein improved mucosal and cellular immunity and enhanced resistance to T. spiralis. The nucleic acid vaccine delivered by invasive L. plantarum described in this study offers a novel idea for the prevention of T. spiralis. [ABSTRACT FROM AUTHOR]

• Constructed recombinant Lactobacillus plantaru m NC8-pLp-TsNd-S-pgsA′-gp43. • Elicited high levels of specific serum IgG and mucosal sIgA. • Mice immunized with recombinant strain exhibited a significant larval reduction. • Protection was associated with a Th2-dominated immune response. Trichinellosis is a significant food-borne zoonotic parasitic disease caused by parasite Trichinella. Given the side effects of anti- Trichinella drugs (e.g., Mebendazole) aroused in the course of treatments, an effective vaccine against the parasite is called for. The therapies available to date are in most instances targeting a single stage of Trichinella , resulting in an incomplete protective immunity against the parasite in terms of the complexity of its developmental stages. In this study, a recombinant dual-expression double anchor vector NC8-pLp-TsNd-S-pgsA′-gp43 was constructed carrying two antigen genes from Trichinella spiralis (T. spiralis), encoding the gp43 and T. spiralis Nudix hydrolase (TsNd) proteins which were mainly expressed in muscle larva (ML) and intestinal infective larva stages of the parasite respectively. These two proteins were to be expressed by Lactobacillus plantarum NC8 (L. plantarum NC8) which was designed to express the two anchored peptides, a truncated poly-γ-glutamic acid synthetase A (pgsA′) and the surface layer protein of Lactobacillus acidophilus (SlpA), on its surface for attaching expressed foreign proteins. Oral immunization with the above recombinant vaccine induced higher levels of specific serum IgG and mucosal secretory IgA (SIgA) in BALB/c mice. In addition, cytokines, interferon-γ (IFN- γ), interleukin-4 (IL-4) and IL-17 released by lymphocytes, and CD4+ levels displayed on the surfaces of splenic and mesenteric lymph cells were significantly enhanced by the vaccination. Moreover, after larval challenges, a 75.67 % reduction of adult worms (AW) at 7 days post-infection (dpi) and 57.14 % reduction of ML at 42 dpi were observed in mice immunized with the recombinant vaccine. Furthermore, this oral vaccination reduced the counts of encysted larvae presented in tongue and masseter muscles after infected with T. spiralis in mice. The overall results demonstrated that the recombinant vaccine developed in this study could induce specific humoral, mucosal, and cellular immune responses, and provides protections against different stages (adult worms and muscle larva) of T. spiralis infections in BALB/c mice, which could make it a promising oral vaccine candidate against trichinellosis. [Display omitted] [ABSTRACT FROM AUTHOR]

• A recombinant L. plantarum expressing the conserved gene of AIV with FliC flagellin was constructed. • Recombinant L. plantarum induced strong T cell immune response in the spleen in chickens. • IgG and sIgA antibodies were elicited by the recombinant L. plantarum in chickens. • Recombinant L. plantarum provided protection against H9N2 AIV. The H9N2 avian influenza virus (AIV) causes serious economic losses to the poultry industry every year. Vaccines that induce a mucosal immune response may be successful against influenza virus infection because its transmission occurs primarily in the mucosa. To develop novel and potent oral vaccines based on Lactobacillus plantarum (L. plantarum) to control the spread of AIV in poultry industry, in the present study, we constructed and expressed fusions of the influenza antigens NP and M2 with the Salmonella Typhimurium flagellinprotein FliC on the surface of L. plantarum. Oral immunization of chicks was performed, and serum antibodies, mucosal antibodies, and specific cellular immunity were detected. Immunizing chicks with avian influenza virus was evaluated. The results showed high levels of IgG in addition to high levels of secretory immunoglobulin A (sIgA) in chickens orally administered recombinant L. plantarum. In addition, the fusion may significantly increase the levels of NP- and M2-specific T cell-mediated immunity in the case of mucosal administration of NC8-pSIP409-pgsA'-NP-M2-FliC. Recombinant NC8-pSIP409-pgsA'-NP-M2-FliC mediated effectively protected chickens against influenza virus and reduced virus titers in the lung. Our study outcomes indicate that the expression of influenza NP-M2 and a mucosal adjuvant (FliC), by L. plantarum could generate a mucosal vaccine candidate for animals in the future to defend against AIVs. [ABSTRACT FROM AUTHOR]

• Recombinant invasive Lactobacillus plantarum expressing TA4-AMA1 was constructed. • T cell differentiation was induced in peripheral blood. • Antibody levels were improved in serum. • Recombinant Lactobacillus plantarum could increase the body weight of chickens. • Oocyst shedding and intestinal lesions were reduced after challenge with oocysts. Coccidiosis is an intestinal parasitic disease that is caused by Eimeria tenella and other species, and it seriously restricts the economic development of the broiler breeding industry. In this study, a recombinant Lactobacillus plantarum with an invasive effect was constructed, and it expressed the TA4-AMA1 protein of E. tenella. After oral immunization with recombinant L. plantarum , specific humoral and mucosal immune levels were measured by indirect ELISA, and the differentiation of T cells was analysed by flow cytometry. After challenge with sporulated oocysts, the body weight, oocyst shedding and cecum lesions of the chicken were evaluated. The results indicated that chickens immunized with recombinant invasive L. plantarum produced higher levels of specific antibodies in the serum than did the non-immunized controls, and the secretory IgA (sIgA) levels were increased in the intestinal washes compared to those of the controls (P < 0.05). Flow cytometry showed that recombinant invasive L. plantarum significantly stimulated T cell differentiation compared to the PBS group (P < 0.01, P < 0.001), and a higher proportion of CD4+ and CD8+ T cells were detected in peripheral blood. Moreover, the lesion scores and histopathological caecum sections showed that immunizing chickens with recombinant invasive L. plantarum can significantly relieve pathological damage in the cecum (P < 0.01), and the relative body weight gain was 89.64 %, which was higher than the 79.83 % gain in the chickens immunized with non-invasive L. plantarum. After the challenge, faeces from ten chickens in each group were collected between 4 and 7 days, and the oocysts per gram (OPG) was determined by the McMaster technique. The data indicated that oocysts in the faeces of chickens immunized with the recombinant invasive L. plantarum were significantly lower than those of the controls (P < 0.01). The results suggest that recombinant invasive L. plantarum effectively activated immune responses against E. tenella infection and can be used as a candidate vaccine against E. tenella infection. [ABSTRACT FROM AUTHOR]

• Constructed recombinant Lactobacillus plantarum NC8-pSIP409- pgsA -mIL-4. • Up-regulated Th2 immune response. • Improved antibody level against Trichinella spiralis. • Mice immunized with recombinant NC8-pSIP409- pgsA -mIL-4 showed reduces parasite loads in intestinal phase and muscular phase. Interleukin-4 (IL-4), an immunomodulatory cytokine derived from activated T lymphocytes were shown to regulate Th2-type immune responses. It plays an important role in anti-parasitic infections. In this study, a recombinant plasmid was designed using murine IL-4 co-expressed with pgsA anchor system of Lactobacillus plantarum NC8 and was delivered by live Lactobacillus plantarum NC8, which exhibited an enhanced immunogenicity in protection of BALB/c mice from infection with Trichinella spiralis. The results showed that the levels of serum IgG1 and mucosal secretory IgA (sIgA) were both increased significantly in mice orally inoculated with NC8-pSIP409- pgsA -mIL-4, and the Th2 phenotype immune response was up-regulated. A 29.9 % reduction in adult worm burden at 7 days post-infection (dpi) and 83.3 % reduction in muscle larvae burden at 28 dpi were observed in immune-stimulated mice with NC8-pSIP409- pgsA -mIL-4. Moreover, weight loss and pathological changes were also improved in mice of NC8-pSIP409- pgsA -mIL-4 group. Taken together, it suggests that NC8-pSIP409- pgsA -mIL-4 could improve the intestinal mucosal immunity and promoted the elimination of the adult worm in Trichinella -infected mice. This study laid the foundation for the development of a novel vaccines against Trichinellosis. [ABSTRACT FROM AUTHOR]