A recombinant vaccine of Riemerella anatipestifer OmpA fused with duck IgY Fc and Schisandra chinensis polysaccharide adjuvant enhance protective immune response

Unveiling the silent threat: A comprehensive review of Riemerella anatipestifer - From pathogenesis to drug resistance

Riemeralla anatipestifer, a predominant bacterium with multidrug resistance, has caused tremendous economic losses in the poultry farming industry. However, there are few studies on its identification, pathogenic mechanisms, and virulence factors and effective and systematic prevention and control strategies. The emergence and spread of antibacterial resistance has prompted increased focus on R. anatipestifer. However, studies on the mechanisms underlying gene aggregation and dissemination are lacking. This review summarizes recent studies on R. anatipestifer and explores its epidemiology, pathobiology, serotype classification, and preventive and treatment measures. Our findings illuminate the characteristics of virulence-related and drug resistance factors that have pivotal roles in the pathogenesis of R. anatipestifer infection. This study provides a comprehensive reference and guidance for in-depth research on R. anatipestifer.

MoxR effects as an ATPase on anti-stress and pathogenicity of Riemerella anatipestifer

Duck infectious serositis is a septicemic disease caused by the bacterium Riemerella anatipestifer (R. anatipestifer), which affects ducks, geese, turkeys, and other poultry. While outbreaks have been reported worldwide, the exact mechanisms of infection and disease progression remain unclear. Our previous research identified the two-component system PhoPR within the genome of R. anatipestifer and demonstrated its association with the bacterium's pathogenicity. Through multi-omics analysis, we found that PhoP directly regulates the expression of several genes, including moxR, within the Bacteroides aerotolerance (Bat) operon. However, the function of MoxR in R. anatipestifer has not yet been reported. To investigate the impact of MoxR on the expression of the bat operon and the pathogenicity of R. anatipestifer, we constructed ΔmoxR and other derivative strains. Our findings revealed that overexpression of MoxR inhibits the transcription of the bat operon. Conversely, deletion of moxR, along with exposure of R. anatipestifer to thermal or oxidative stress, results in increased transcription levels of the bat operon. By measuring the survival ability of each strain under stress, we discovered that MoxR is closely associated with the resistance of R. anatipestifer to thermal and oxidative stress by influencing the expression of the bat operon. Duckling infection experiments, along with adhesion and invasion assays, showed that deletion of moxR in R. anatipestifer led to decreased pathogenicity, and lower bacterial load in various tissues. Collectively, our findings collectively demonstrate the significant role of MoxR in the anti-stress and pathogenicity of R. anatipestifer, providing new insights into its pathogenic mechanisms.

Application of plant-derived products as adjuvants for immune activation and vaccine development

Vaccines are one of the most important means to prevent and control the epidemic of infectious diseases. Commercial vaccines not only include corresponding antigens, but also need vaccine adjuvants. Immune adjuvants play an increasingly important role in the research, development and manufacture of vaccines. Adjuvants combined with antigens can improve the stability, safety and immune efficiency of vaccines. Some substances that can enhance the immune response have been found in nature(mainly plants) and used as adjuvants in vaccines to improve the immune effect of vaccines. These plant-derived immune adjuvants often have the advantages of low toxicity, high stability, low price, etc., providing more possibilities for vaccine development. We summarized and analyzed the advantages, application research, particulate delivery systems, existing problems and future research focus of botanical adjuvant. It is hoped to provide new ideas for the research and development of immune adjuvants in the future.

Schisandra chinensis (Turcz.) Baill neutral polysaccharides alleviate Parkinson's disease via effectively activating MCL-1 expression regulation of autophagy signaling

The purified neutral polysaccharide fraction, namely SBP-1, was isolated and characterized from Schisandra chinensis (Turcz.) Baill crude polysaccharides, which have anti-Parkinson's disease activity were investigated in vivo and in vitro. Experiments have shown that the main chain of SBP-1 was Glcp-(1→, →4)-Glcp-(1→ and →4,6)-Glcp-(1→. We also revealed the effect of SBP-1 on the PD mice model and the potential underlying molecular mechanism. The results showed that SBP-1 administration improved behavioral deficits, increased tyrosine hydroxylase-positive cells, attenuated loss of dopaminergic neurons in MPTP-exposed mice, and reduced cell death induced by MPP+. The MCL-1 was identified as the target of SBP-1 by the combination of docking-SPR-ITC, WB, and IF experiments. Subsequently, the study showed that SBP-1 could target MCL-1 to enhance autophagy with a change in the apoptotic response, which was further demonstrated by a change in LC3/P62, PI3K/AKT/mTOR, and possesses a change in the expression of BCL2/BAX/Caspase3. These results demonstrate that SBP-1 may protect neurons against MPP+ or MPTP-induced damage in vitro and in vivo through enhancing autophagy. In summary, these findings indicate that SBP-1 and S. chinensis show potential as effective candidates for further investigation in the prevention and treatment of PD or associated illnesses, specifically through autophagy apoptotic-based mechanisms.

Extraction, purification, structural characterization, and biological activity of polysaccharides from Schisandra chinensis: A review

Schisandra chinensis (SC), a plant of the Magnoliaceae family, commonly known as "North Schisandra chinensis", has been listed as a top-grade Chinese medicine in the Shennong Materia Medica Classic for its high medicinal value since ancient times. Polysaccharides from S. chinensis fruits (SCPs) are an active component in SC, which have various biological activity, including immune regulation, anti-tumor, antioxidant, liver protective, anti-inflammatory and hypoglycemic activity. Research has shown that the extraction methods of SCPs include hot water extraction, water extraction and alcohol precipitation, ultrasonic-assisted, microwave-assisted and so on. Different extraction methods can affect the yield and purity of polysaccharides, and to improve the extraction yield of SCPs, two or more extraction methods can be combined. SCPs are mainly composed of glucose, mannose, rhamnose, galactose, galacturonic acid and arabinose. This article aims to provide a systematic review of the research progress in the extraction and separation methods, structural characterization, and biological activity of SCPs both domestically and internationally in recent years. This deeply explores the pharmacological activity and action mechanism of SCPs, and provides a certain point of reference for the research and clinical application of SC.

A novel bivalent inactivated vaccine for ducks against Riemerella anatipestifer based on serotype distribution in southern China

Riemerella anatipestifer (RA) causes epizootic infectious polyserositis in ducks with high mortality and leads to huge economic losses worldwide. Bacterial resistance poses a challenge for the control of the disease, vaccines failed to provide ideal cross-protection. Thus, the preparation of vaccines based on popular serotypes is important. In this study, we collected 700 brain and liver tissues of dead ducks from 8 provinces in southern China from 2016 to 2022 and obtained 195 RA isolates with serotypes 1, 2, 7, and 10. Serotypes 1 and 2 were the most prevalent (82%). A novel bivalent inactivated vaccine WZX-XT5 containing propolis adjuvant was prepared, we chose XT5 (serotype 1) and WZX (serotype 2) as vaccine strains and evaluated WZX-XT5-induced immune response and protective efficacy in ducks. Results showed that the XT5 (LD50, 3.5 × 103 CFU) exhibited high virulence and provided better protection against RA compared with ZXP, DCR and LCF1 (LD50, 108 CFU). Notably, the dose of 109 CFU provided ideal protection compared with 108 CFU, propolis and oil emulsion adjuvants induced stronger protective efficacy compared with aluminum hydroxide adjuvant. Importantly, WZX-XT5 immunization induced high levels of RA-specific IgY, IFN-γ, IL-2, and IL-4 in serum and offered over 90% protection against RA with ultra-high lethal dose in ducks. Additionally, no clinical signs of RA infection or obvious pathological damage in tissues were observed in protected ducks. Overall, this study first reports the identification, serotyping and virulence of RA in ducks of southern China and the preparation of a novel bivalent inactivated vaccine, providing useful scientific information to prevent and control RA infection.

The extraction, purification, structural features, bioactivities, and applications of Schisandra chinensis polysaccharides: A review

Schisandra chinensis, as a famous medicinal and food homologous plant, has a long history of medicinal and dietary therapy. It has the functions of nourishing the kidney, calming the heart, tranquilising the mind, tonifying Qi and producing fluid to relieve mental stress, based on the theory of traditional Chinese medicine. Accumulating evidence has shown that S. chinensis polysaccharides (SCPs) are one of the most important bioactive macromolecules and exhibit diverse biological activities in vitro and in vivo, including neuroprotective, hepatoprotective, immunomodulatory, antioxidant, hypoglycemic, cardioprotective, antitumour and anti-inflammatory activities, etc. This review aims to thoroughly review the recent advances in the extraction and purification methods, structural features, biological activities and structure-activity relationships, potential applications and quality assessment of SCPs, and further highlight the therapeutic potentials and health functions of SCPs in the fields of therapeutic agents and functional food development. Future insights and challenges of SCPs were also critically discussed. Overall, the present review provides a theoretical overview for the further development and utilization of S. chinensis polysaccharides in the health food and pharmaceutical fields.

In Silico Analysis and Immune Response of YaeT Protein Against Riemerella anatipestifer in Ducks

Riemerella anatipestifer (RA) is one of the most harmful bacterial pathogens in waterfowl and causes enormous economic loss worldwide. Due to weak cross-immunity protection against different serotypes of RA, inactivated and attenuated vaccines are only effective for RA of specific serotypes. In this paper, outer membrane protein YaeT in RA was analyzed through bioinformatics, in vivo, and in vitro assays. Homology, physicochemical and structural properties, transmembrane domains, and B-cell binding epitopes were investigated. The recombinant outer membrane protein YaeT was then inoculated into Cherry Valley ducks to analyze its immune protection against RA. Results showed that the protein was conservative in different RA strains and had sufficient B-cell binding epitopes. The immunized duck serum contains high-affinity antibodies that could activate complement and promote the opsonophagocytosis of RA by phagocytes. After RA challenge, the survival rate of the YaeT protein-immunized ducks was 80%.

Schisandra chinensis (Turcz.) Baill. polysaccharide inhibits influenza A virus in vitro and in vivo

Influenza virus is prone to seasonal spread and widespread outbreaks, which pose important challenges to public health security. Therefore, it is important to effectively prevent and treat influenza virus infection. Schisandra polysaccharide (SPJ) is a polysaccharide derived from the fruit of Schisandra chinensis (Turcz.) Baill. In this study, we evaluated the antiviral activity of SPJ in vitro and in vivo, especially against influenza A virus (IAV) infection. By analyzing SPJ structure and monosaccharide composition, the molecular weight of SPJ was determined to be 115.5 KD, and it is composed of galacturonic acid (89.4%), rhamnose (0.8%), galactose (4.4%), arabinose (3.8%), and glucose (1.7%). Immunofluorescence analysis showed that SPJ treatment reduced the positive rate of viral nucleoproteins in cells, indicating that the compound had an inhibitory effect on influenza virus replication. Furthermore, SPJ therapy improved the survival of infected mice. Lung virus titer assays indicated that SPJ treatment significantly reduced viral loading in the lung tissue of infected mice and alleviated the pathological damage caused by influenza virus infection. Moreover, SPJ reduced cytokine expression during influenza virus challenge. In conclusion, SPJ has anti-influenza virus effects and may have potential as an anti-influenza drug candidate in further clinical studies.

Effects of dietary nano-selenium supplementation on Riemerella anatipestifer vaccinated and challenged Pekin ducklings (Anas platyrhynchos)

Riemerella anatipestifer (RA) is a common disease causing economic losses to duck farms worldwide. Novel supplements are crucially needed to control this bacterium, enhance poultry performance, and produce synergistic effects with vaccines in stimulating the immune system. This study investigated the effect of nano-selenium (Nano-Se) on the vaccinated (VAC) and challenged (Ch) Pekin ducklings (Anas platyrhynchos) with RA. Five experimental groups (G1-G5) were included in this study: G1 was the control group, G2 was the RA-challenged group, G3 was the Nano-Se+Ch group, G4 was the VAC+Ch group, and G5 was the Nano-Se+VAC+Ch group. The Nano-Se (0.3 mg/kg diet) was supplemented for 5 weeks post-vaccination (PV). The ducklings were vaccinated subcutaneously with the RA vaccine at 7 days of age and challenged with RA at the 3rd week PV. Blood, pharyngeal swabs and tissue samples were collected at the 3rd week PV and at different times post-challenge (PC). The growth performance (weight gain and feed conversion ratio), clinical signs, gross lesions, mortality, bacterial shedding, haematological, immunological, and biochemical parameters, cytokines production, and histopathological lesion scores showed significant differences (P < 0.05) between the challenged (G2) group and the supplemented (G3 & G5) groups. G5 showed the highest (P < 0.05) growth performance, phagocytic activity, IgM and IgG, splenic interleukin-2 (IL-2), IL-10, and interferon-gamma (IFN-γ) gene expressions, and the lowest mortality, bacterial shedding, hepatic and renal damage, heterophil/lymphocyte ratio and lesion scores compared to the other groups. In conclusion, the supplementation of nano-selenium for five weeks in the diet can improve the growth performance, immune status, and cytokines production in ducklings vaccinated and challenged with RA.

Sifting through the core-genome to identify putative cross-protective antigens against Riemerella anatipestifer

Infectious serositis of ducks, caused by Riemerella anatipestifer, is one of the main infectious diseases that harm commercial ducks. Whole-strain-based vaccines with no or few cross-protection were observed between different serotypes of R. anatipestifer, and so far, control of infection is hampered by a lack of effective vaccines, especially subunit vaccines with cross-protection. Since the concept of reverse vaccinology was introduced, it has been widely used to screen for protective antigens in important pathogens. In this study, pan-genome binding reverse vaccinology, an emerging approach to vaccine candidate screening, was used to screen for cross-protective antigens against R. anatipestifer. Thirty proteins were identified from the core-genome as potential cross-protective antigens. Three of these proteins were recombinantly expressed, and their immunoreactivity with five antisera (anti-serotypes 1, 2, 6, 10, and 11) was demonstrated by Western blotting. Our study established a method for high-throughput screening of cross-protective antigens against R. anatipestifer in silico, which will lay the foundation for the development of a cross-protective subunit vaccine controlling R. anatipestifer infection. KEY POINTS: • Pan-genome binding reverse vaccine approach was first established in R. anatipestifer to screen for subunit vaccine candidates. • Thirty potential cross-protective antigens against R. anatipestifer were identified by this method. • The reliability of the method was verified preliminarily by the results of Western blotting of three of these potential antigens.

Immunogenicity of live phoP gene deletion strain of Riemerella anatipestifer serotype 1

Duck infectious serositis is an acute and infectious disease caused by Riemerella anatipestifer (R. anatipestifer) that leads to perihepatitis, pericarditis, meningitis, and airbag inflammation in ducks, which causes serious economic losses to the global duck industry. The phoP/phoR is a novel 2-component signal transduction system first reported in gram-negative bacteria, of which phoP acts as a global regulator and virulence factor. In this study, the phoP gene from the R. anatipestifer YM strain was knocked out using homologous recombination technology and replaced with the spectinomycin resistance gene (Spec). The virulence of the R. anatipestifer YMΔphoP strain was reduced by approximately 47,000 times compared to that of the wild-type R. anatipestifer YM strain. Ducks were immunized with live R. anatipestifer YMΔphoP strain by subcutaneous inoculation at a dose of 10⁶ to 10⁷ CFU (0.2 mL per duck) and challenged with the wild-type R. anatipestifer YM strain 14 days later. The protection rate in the immunized group was 100%. The growth characteristics of ducks in the immunized and negative control groups were normal, and the research demonstrated R. anatipestifer YMΔphoP strain have suitable immunogenicity and protective effects. Thus, the study findings suggest that the novel R. anatipestifer YMΔphoP strain may provide a candidate for the development of a gene deletion activated vaccine against duck infectious serositis.

Effects of Chinese yam polysaccharides on the immune function and serum biochemical indexes of broilers

The purpose of this experiment was to investigate the effects of Chinese yam polysaccharides (CYP) in diets on the immune function of broilers. A total of 360 (1-day-old, sex balance) healthy growing broilers with similar body weight (39.54 ± 0.51 g) were randomly divided into control (0.00 g/kg), CYP I (0.25 g/kg), CYP II (0.50 g/kg), and CYP III (1.00 g/kg) groups. Each group contains 3 replicates with 30 broilers in each replicate, and the feeding trial lasted 48 d. The results showed that compared with the control group, the CYP II group had higher thymus index, serum IgA, complement C3, C4, IGF-I, T₃, T₄, INS, GH, IL-2, IL-4, IL-6, and TNF-α levels (P < 0.05) at 28, 48 d, respectively. In addition, the spleen index, serum IgM and IgG concentrations in CYP II group were higher than those in the control group at 28 d (P < 0.05). Results indicated that 0.50 g/kg CYP supplementation improved the immune function of broilers, and the CYP has a potential biological function as a green additive in broilers.

Characterizations of glucose-rich polysaccharides from Amomum longiligulare T.L. Wu fruits and their effects on immunogenicities of infectious bursal disease virus VP2 protein

The aim of this study is to explore the characterization of Amomum longiligulare T.L. Wu fruits polysaccharide (ALP) and their immune enhancement effects. Two homogeneous polysaccharides (ALP1 and ALP2) were isolated from the fruits. The structural characterization results showed that ALP1 (26.10 kDa) and ALP2 (64.10 kDa) were both mainly composed of glucose. Furthermore, ALP1 was consisted of (1,2)-α-D-Glcp, (1,2,3)-α-D-Glcp and T-α-D-Glcp, while ALP2 was consisted of T-α-D-Glcp, (1,3)-α-D-Glcp and (1,3,6)-α-D-Glcp. Afterwards, the immune enhancement effects of two polysaccharides were evaluated by determining their effects on immunogenicities of infectious bursal disease virus (IBDV) VP2 protein. Chickens were immunized with IBDV VP2 protein accompanied with ALP1/ALP2. And the results indicated both ALP1 and ALP2 promoted the weights and bursa of fabricius indexes of chickens. In addition, both two polysaccharides increased specific IBDV antibody levels, while ALP1 possessed higher immune enhancement ability and was expected to be an adjuvant for IBDV VP2 protein.

Traditional Chinese Medicine Jiuwei Zhenxin Granules in Treating Depression: An Overview

Depression is known as "Yu Zheng" in traditional Chinese medicine (TCM). Jiuwei Zhenxin granules (JZG) is a type of TCM. According to TCM theory, it nourishes the heart and spleen, tonifies Qi, and tranquilizes the spirit, and may also has effects in the treatment of depression. Here, we systematically reviewed recent basic and clinical experimental studies of JZG and depression, including studies of the pharmacological mechanisms, active ingredients, and clinical applications of JZG in depression treatment. This review will deepen our understanding of the pharmacological mechanisms, drug interactions, and clinical applications of TCM prescriptions and provide a basis for the development of new drugs in the treatment of depression.