The impact of Aloe vera and licorice extracts on selected mechanisms of humoral and cell-mediated immunity in pigeons experimentally infected with PPMV-1

The pigeon circovirus evolution, epidemiology and interaction with the host immune system under One Loft Race rearing conditions

This study was aimed to investigate the frequency of PiCV recombination, the kinetics of PiCV viremia and shedding and the correlation between viral replication and host immune response in young pigeons subclinically infected with various PiCV variants and kept under conditions mimicking the OLR system. Fifteen racing pigeons originating from five breeding facilities were housed together for six weeks. Blood and cloacal swab samples were collected from birds every seven days to recover complete PiCV genomes and determine PiCV genetic diversity and recombination dynamics, as well as to assess virus shedding rate, level of viremia, expression of selected genes and level of anti-PiCV antibodies. Three hundred and eighty-eight complete PiCV genomes were obtained and thirteen genotypes were distinguished. Twenty-five recombination events were detected. Recombinants emerged during the first three weeks of the experiment which was consistent with the peak level of viremia and viral shedding. A further decrease in viremia and shedding partially corresponded with IFN-γ and MX1 gene expression and antibody dynamics. Considering the role of OLR pigeon rearing system in spreading infectious agents and allowing their recombination, it would be reasonable to reflect on the relevance of pigeon racing from both an animal welfare and epidemiological perspective.

Investigating pigeon circovirus infection in a pigeon farm: molecular detection, phylogenetic analysis and complete genome analysis

BACKGROUND

Pigeon circovirus infections in pigeons (Columba livia domestica) have been reported worldwide. Pigeons should be PiCV-free when utilized as qualified experimental animals. However, pigeons can be freely purchased as experimental animals without any clear guidelines to follow. Herein, we investigated the status quo of PiCV infections on a pigeon farm in Beijing, China, which provides pigeons for experimental use.

RESULTS

PiCV infection was verified in at least three types of tissues in all forty pigeons tested. A total of 29 full-length genomes were obtained and deposited in GenBank. The whole genome sequence comparison among the 29 identified PiCV strains revealed nucleotide homologies of 85.8-100%, and these sequences exhibited nucleotide homologies of 82.7-98.9% as compared with those of the reference sequences. The cap gene displayed genetic diversity, with a wide range of amino acid homologies ranging from 64.5% to 100%. Phylogenetic analysis of the 29 full-genome sequences revealed that the PiCV strains in this study could be further divided into four clades: A (17.2%), B (10.4%), C (37.9%) and D (34.5%). Thirteen recombination events were also detected in 18 out of the 29 PiCV genomes obtained in this study. Phylogenetic research using the rep and cap genes verified the recombination events, which occurred between clades A/F, A/B, C/D, and B/D among the 18 PiCV strains studied.

CONCLUSIONS

In conclusion, PiCV infection, which is highly genetically varied, is extremely widespread on pigeon farms in Beijing. These findings indicate that if pigeons are to be used as experimental animals, it is necessary to evaluate the impact of PiCV infection on the results.

Enhancing effects of Aloe vera gel extracts on the humoral and cellular immune response and growth performance in broiler chickens

Objective

The experiment evaluated how Aloe vera gel (AVG) extract supplementation affected immune responses and physiological performances in broiler chickens.

Materials and Methods

90-day-old Cobb 500 broiler chicks were reared for 38 days without the addition of antibiotics, either through feed or water. At 10 days, chicks were allocated into three groups: A, B, and C (n = 30). Group A served as non-supplemented control. Groups B and C were administered aqueous extracts of AVG at 1.0% and 2.0%, respectively, with drinking water.

Results

The supplementation of AVG potentiated the chicken immune response to Newcastle disease-vaccinated birds and sheep red blood cell-treated birds, which detected the highest antibody titers against Newcastle disease virus and sRBC. The cellular immune response evaluated through a cutaneous basophilic hypersensitivity test using phytohemagglutinin-P demonstrated a significant increase in skin thickness in AVG-supplemented birds. The relative sizes of lymphoid organs (bursa, spleen, and thymus) were significantly enhanced (p < 0.05) among the groups. Broilers given AVG-1 and AVG-2 exhibited significantly greater (p < 0.01) live body weight, dressing percentages, and serum protein and serum albumin levels. The supplemented groups experienced a significant reduction in total serum cholesterol, triglycerides, and low-density lipoprotein-cholesterol values, while the levels of high-density lipoprotein-cholesterol remained unchanged. The dietary aqueous extracts of AVG are effective in enhancing innate and specific immunity.

Conclusion

This work strengthens the perspective of the use of AVG as an immune stimulant to facilitate recovery from immune suppression states, enhance innate and specific immunity, and improve broiler growth performance.

Rapid increase in immune surveillance and expression of NKT and γδT cell activation markers after consuming a nutraceutical supplement containing Aloe vera gel, extracts of Poria cocos and rosemary. A randomized placebo-controlled cross-over trial

GOAL

To evaluate the acute impact of a nutraceutical blend on immune surveillance.

STUDY DESIGN

A randomized, double-blind, placebo-controlled, cross-over trial was conducted in 11 healthy subjects. Blood samples were taken immediately before and at 1, 2, and 3 hours after consuming placebo or 500 mg of UP360, which is a blend of botanicals from Aloe vera, Poria cocos, and rosemary (APR extract). Immunophenotyping and flow cytometry quantified numbers of monocytes, NK cells, NKT cells, CD8+ cytotoxic T cells, γδT cells, and total T cells, and expression of CD25 and CD69 activation markers. Plasma was tested for cytokines, chemokines, growth factors, and enzymatic activity of superoxide dismutase and catalase.

RESULTS

Compared to the placebo, consumption of APR extract triggered rapid increases in chemokine levels starting at 1 hour, including IP-10 (P<0.05) and MCP-1 (P<0.1), which peaked at 2 hours (P<0.01) and 3 hours (P<0.05), respectively. The stem cell-mobilizing growth factor G-CSF increased at 2 hours (P<0.05). Increased immune surveillance involved a transient effect for monocytes at 1 hour, followed by NKT cells, CD8+ cytotoxic T cells, and γδT cells at 2-3 hours. Increased immune cell alertness was seen at 1 hour by increased CD25 expression on monocytes (P<0.01), NKT cells (P<0.01), and T cells (P<0.05). NKT cells showed upregulation of CD69 at 2 hours (P<0.01). Increased enzymatic activity was seen at 2 hours for the antioxidant enzymes superoxide dismutase (P<0.05) and catalase (P<0.01).

CONCLUSION

Consumption of APR extract triggered acute changes to chemokine levels. In addition, immune alertness was increased via the expression of activation markers on multiple types of innate immune cells, followed by increased immune surveillance and antioxidant protection. This suggests a beneficial enhancement of natural immune surveillance, likely via a combination of gut-mediated cytokine release and vagus nerve communication, in combination with cellular protection from oxidative stress.

Immunopathological studies on Escherichia coli infected broiler chickens fed on Aloe vera leaf extract

Escherichia coli infection is the major bacterial disease affecting the poultry industry and the continuous use of antibiotics in poultry farming has resulted in antibiotic resistance. So this study was planned to evaluate the use of an ecologically safe alternative to fight against infections. The leaf gel of the Aloe vera plant was selected based on its antibacterial activity assessed in in-vitro tests. The objective of the present study was to evaluate the effect of A. vera leaf extract supplementation on the severity of clinical signs and pathological lesions, mortality rate, levels of antioxidant enzymes, and immune response in experimentally E. coli-infected broiler chicks. Broiler chicks were supplemented with aqueous Aloe vera Leaf (AVL) extract @ 20 ml per liter of water from day one of age. After seven days of age, they were experimentally infected with E. coli O78 @ 10⁷ CFU/0.5 ml intraperitoneally. Blood was collected at weekly intervals up to 28 days and assayed for antioxidant enzyme assays, and humoral and cellular immune response. The birds were observed daily for clinical signs and mortality. Dead birds were examined for gross lesions and representative tissues were processed for histopathology. The activities of antioxidants, Glutathione reductase (GR), and Glutathione-S-Transferase (GST) were significantly higher than the control infected group. The E. coli-specific antibody titer and Lymphocyte stimulation Index were comparatively higher in the AVL extract-supplemented infected group as compared to the control infected group. No considerable change was noted in the severity of clinical signs and pathological lesions, and mortality. Thus, Aloe vera Leaf gel extract enhanced the antioxidant activities and cellular immune responses of infected broiler chicks to combat this infection.

Research progress on the mechanisms underlying poultry immune regulation by plant polysaccharides

With the rapid development of poultry industry and the highly intensive production management, there are an increasing number of stress factors in poultry production. Excessive stress will affect their growth and development, immune function, and induce immunosuppression, susceptibility to a variety of diseases, and even death. In recent years, increasing interest has focused on natural components extracted from plants, among which plant polysaccharides have been highlighted because of their various biological activities. Plant polysaccharides are natural immunomodulators that can promote the growth of immune organs, activate immune cells and the complement system, and release cytokines. As a green feed additive, plant polysaccharides can not only relieve stress and enhance the immunity and disease resistance of poultry, but also regulate the balance of intestinal microorganisms and effectively alleviate all kinds of stress faced by poultry. This paper reviews the immunomodulatory effects and molecular mechanisms of different plant polysaccharides (Atractylodes macrocephala Koidz polysaccharide, Astragalus polysaccharides, Taishan Pinus massoniana pollen polysaccharide, and alfalfa polysaccharide) in poultry. Current research results reveal that plant polysaccharides have potential uses as therapeutic agents for poultry immune abnormalities and related diseases.

Revisiting liquorice (Glycyrrhiza glabra L.) as anti-inflammatory, antivirals and immunomodulators: Potential pharmacological applications with mechanistic insight

BACKGROUND

Glycyrrhiza glabra L. (G. glabra) commonly known as liquorice is one of the highly exploited and utilized medicinal plant of the world. Since ancient times liquorice is considered as an auspicious and valuable traditional medicine across the world for treatment of various ailments.

METHOD

Several electronic online scientific databases such as Science Direct, PubMed, Scopus, Scifinder, Google Scholar, online books and reports were assessed for collecting information. All the collected information was classified into different sections to meet the objective of the paper.

RESULTS

The electronic database search yielded 3908 articles from different countries. Out of them one ninety-eight articles published between 1956 and 2021 were included, corresponding to all detailed review on G. glabra and research on anti-inflammatories, antivirals and immunomodulatory through pre-clinical and clinical models. From all selective area of studies on G. glabra and its bioactive components it was established (including molecular mechanisms) as a suitable remedy as per the current requirement of pandemic situation arise through respiratory tract infection.

CONCLUSION

Different relevant studies have been thoroughly reviewed to gain an insight on utility of liquorice and its bioactive constituents for anti-inflammatories, antivirals and immunomodulatory effects with special emphasized for prevention and treatment of COVID-19 infection with possible mechanism of action at molecular level. Proposed directions for future research are also outlined to encourage researchers to find out various mechanistic targets and useful value added products of liquorice in future investigations.

Immunobiology and Application of Aloe Vera-Based Scaffolds in Tissue Engineering

Aloe vera (AV), a succulent plant belonging to the Liliaceae family, has been widely used for biomedical and pharmaceutical application. Its popularity stems from several of its bioactive components that have anti-oxidant, anti-microbial, anti-inflammatory and even immunomodulatory effects. Given such unique multi-modal biological impact, AV has been considered as a biomaterial for regenerative medicine and tissue engineering applications, where tissue repair and neo-angiogenesis are vital. This review outlines the growing scientific evidence that demonstrates the advantage of AV as tissue engineering scaffolds. We particularly highlight the recent advances in the application of AV-based scaffolds. From a tissue engineering perspective, it is pivotal that the implanted scaffolds strike an appropriate foreign body response to be well-accepted in the body without complications. Herein, we highlight the key cellular processes that regulate the foreign body response to implanted scaffolds and underline the immunomodulatory effects incurred by AV on the innate and adaptive system. Given that AV has several beneficial components, we discuss the importance of delving deeper into uncovering its action mechanism and thereby improving material design strategies for better tissue engineering constructs for biomedical applications.

Probiotic supplementation containing Bacillus velezensis enhances expression of immune regulatory genes against pigeon circovirus in pigeons (Columba livia)

AIMS

In this study, we aimed to isolate and evaluate the efficacy of Bacillus velezensis as a probiotic and to assess its activity towards pigeons infected with pigeon circovirus (PiCV).

METHODS AND RESULTS

Bacillus velezensis, isolated from pigeon faeces, was orally administered to pigeons for 60 days. After pigeons were challenged with PiCV, the PiCV viral load and expression of indicator genes for innate immunity were detected in spleen tissue and faeces of pigeons. Bacillus velezensis significantly reduced the PiCV viral load in the faeces and spleen of pigeons 5 days post-challenge (dpc). The mRNA expression levels of treated pigeons showed that interferon-gamma (IFN-γ), myxovirus resistance 1 (Mx1), and signal transducers and activators of transcription 1 (STAT1) genes were upregulated, whereas no expression of interleukin-4 (IL-4) was detected. Moreover, toll-like receptor 2 (TLR2) and 4 (TLR4) were significantly upregulated in probiotic-treated pigeons (P < 0·05).

CONCLUSIONS

This is the first report showing that probiotic supplementation can effectively enhance the T-helper type 1 immune response and decrease the PiCV viral loads in pigeons.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study proposes that the administration of a probiotic strain, B. velezensis, to pigeons can protect against PiCV infection.

The Clinical Infection with Pigeon Circovirus (PiCV) Leads to Lymphocyte B Apoptosis But Has No Effect on Lymphocyte T Subpopulation

The pathology of pigeon circovirus (PiCV) is still unknown, but it is regarded as an immunosuppressant. This study aimed to find a correlation between PiCV natural infection and immunosuppression. The study was conducted with 56 pigeons divided into the following groups: PiCV-positive but showing (group S) or not (group I) non-specific clinical symptoms and asymptomatic pigeons negative for PiCV (group H). The percentage and apoptosis of T CD3⁺ and B IgM⁺ splenocytes; the expression of CD4, CD8, and IFN-γ genes in splenic mononuclear cells; the number of PiCV viral loads in the bursa of Fabricius; and the level of anti-PiCV antibodies were analyzed. The results showed that the percentage of B IgM⁺ cells was almost two-fold lower in group S than in group H, and that ca. 20% of the lymphocytes were apoptotic. No increased apoptosis was detected in TCD3⁺ subpopulation. The PiCV viral loads were approximately one thousand and ten thousand times higher in group S than in groups I and H, respectively. Our results indicate a possible correlation between the number of PiCV viral loads and severity of PiCV infection and confirm that PiCV infection leads to the suppression of humoral immunity by inducing B lymphocyte apoptosis.

Common bacterial, viral, and parasitic diseases in pigeons (Columba livia): A review of diagnostic and treatment strategies

Pigeons (Columba livia) have been associated with humans for a long time now. They are raised for sport (pigeon race), exhibition (display of fancy breeds), food, and research. Most of the pigeons kept are Racing Homers, trained to compete in the pigeon race. Other breeds, such as Rollers, Nose Divers, Doneks are bred for their aerial abilities. Incorporation of a good preventive medicine program is one of the most critical factors in averting infectious diseases in pigeon flocks. This review summarizes the common bacterial, viral, and parasitic infections in pigeons. The different clinical signs, symptoms, diagnostic strategies, prevention, and treatments were described in this review. Current researches, molecular diagnostic assays, and treatment strategies such as vaccines and drug candidates were included. The information found in this review can provide insights for veterinarians and researchers studying pigeons to develop effective and efficient immunoprophylactic and diagnostic tools for pigeon diagnosis and therapeutics.

Influence of pigeon interferon alpha (PiIFN-α) on pigeon circovirus (PiCV) replication and cytokine expression in Columba livia

Pigeon circovirus (PiCV) is the most diagnosed virus in pigeons (Columba livia) and have been studied and reported globally. PiCV infections can lead to immunosuppression and pigeons infected with PiCV can result to lymphocyte apoptosis and atrophy of immune organs. Young pigeon disease syndrome (YPDS) is a complex disease and believed that PiCV could be one of the agents leading to this syndrome. An effective treatment regimen is needed to control the spread of PiCV in pigeons. In this study pigeon interferon alpha (PiIFN-α) was cloned and expressed and its antiviral effects were tested against fowl adenovirus type 4 (FAdV-4) in vitro and PiCV in vivo. No detectable levels of FAdV-4 viral genome in LMH cells stimulated with 300 μg/mL PiIFN-α were found. Additionally, PiIFN-α was stable at different temperature and pH for 4 h, and no reduction in antiviral activity was observed in untreated and treated cells. In pigeons naturally and experimentally infected by PiCV, no detectable levels of PiCV virus titers were found after treatment with PiIFN-α. Cytokine and ISG expression levels in liver and spleen samples were detected and IFN-γ and Mx1 genes were dominantly up-regulated following PiIFN-α treatment (p < 0.05). This study demonstrated that PiCV can be inhibited by administration of PiIFN-α and PiFN-α can be used as a therapeutic approach to prevent the spread of PiCV in pigeons.

Use of Licorice (Glycyrrhiza glabra) Herb as a Feed Additive in Poultry: Current Knowledge and Prospects

Simple Summary

The present review updates the current knowledge about the beneficial effect of licorice supplementation in poultry diets, particularly its positive effect on the treatment of high-prevalence diseases of the immune system, liver, and lungs.

Abstract

Supplementation of livestock and poultry diets with herbal plants containing bioactive components have shown promising reports as natural feed supplements. These additives are able to promote growth performance and improve feed efficiency, nutrient digestion, antioxidant status, immunological indices, and poultry health. Several studies have used complex herbal formulas with the partial inclusion of licorice. However, the individual use of licorice has been rarely reported. The major problem of the poultry industry is the epidemiological diseases, mainly confined to the respiratory, digestive, and immune systems. Licorice has certain bioactive components such as flavonoids and glycyrrhizin. The roots of this herb contain 1 to 9% glycyrrhizin, which has many pharmacological properties such as antioxidant, antiviral, anti-infective and anti-inflammatory properties. Licorice extracts (LE) have a positive effect on the treatment of high-prevalence diseases such as the immune system, liver, and lung diseases. Studies showed that adding LE to drinking water (0.1, 0.2, or 0.3 g/L) reduced serum total cholesterol (p < 0.05) of broiler chickens. Moreover, LE supplementation in poultry diets plays a significant role in their productive performance by enhancing organ development and stimulating digestion and appetite. Along with its growth-promoting effects, licorice has detoxifying, antioxidant, antimicrobial, anti-inflammatory, and other health benefits in poultry. This review describes the beneficial applications and recent aspects of the Glycyrrhiza glabra (licorice) herb, including its chemical composition and role in safeguarding poultry health.

Comparison of the immune response to vaccination with pigeon circovirus recombinant capsid protein (PiCV rCP) in pigeons uninfected and subclinically infected with PiCV

Infections with immunosuppressive pigeon circovirus (PiCV) pose the most severe health problem to the global pigeon breeding. The vaccination with immunogenic PiCV recombinant capsid protein (PiCV rCP) is a potential tool for disease control. Because of the high prevalence of PiCV asymptomatic infections, the subclinically infected pigeons will be vaccinated in practice. The aim of this study was to answer a question if vaccination of asymptomatic, infected with PiCV pigeons induces a similar immune response to PiCV rCP as in uninfected birds. One hundred and twenty 6-week-old carrier pigeons were divided into 4 groups (2 groups of naturally infected and uninfected with PiCV individuals). Birds from groups V and V1 were vaccinated twice with PiCV rCP mixed with an adjuvant, whereas pigeons from groups C and C1 were immunized with an adjuvant only. The expression of genes encoding IFN-γ, CD4, and CD8 T lymphocyte receptors; the number of anti-PiCV rCP IgY-secreting B cells (SBC) and anti-PiCV rCP IgY were evaluated 2, 21, 39 and 46 days post vaccination (dpv). Study results showed that the expression of CD8 and IFN-γ genes was higher in both groups of infected pigeons than in the uninfected birds, irrespective of vaccination. In the uninfected birds, the expression of these genes was insignificantly higher in the vaccinated pigeons. The anti-PiCV rCP IgY-SBC were detected on 2 and 23 dpv and seroconversion was noted on 23 and 39 dpv in V and V1 groups, respectively. In the light of the results obtained, it could be concluded that pigeon circovirus recombinant capsid protein elicits the immune response in both naturally infected and uninfected pigeons, but its rate varies depending on PiCV infectious status. The infection with PiCV masks the potential cellular immune response to the vaccination with PiCV rCP and leads to the suppression of humoral immunity.

Antibacterial activity and mode of action of acetone crude leaf extracts of under-investigated Syzygium and Eugenia (Myrtaceae) species on multidrug resistant porcine diarrhoeagenic Escherichia coli

BACKGROUND

Diarrhoea, a global economically important disease burden affecting swine and, especially piglets, is commonly caused by infection with entero-toxigenic E. coli (ETEC). Adherence of ETEC to porcine intestinal epithelial cells following infection, is necessary for its pathogenesis. While antimicrobials are commonly given as therapy or as feed additives for prophylaxis against microbial infections, the concern over increased levels of antimicrobial resistance necessitate the search for safe and effective alternatives in livestock feed. Attention is shifting to natural products including plants as suitable alternatives to antimicrobials. The activity of acetone crude leaf extracts of nine under-explored South African endemic plants from the Myrtaceae family with good antimicrobial activity were tested against pathogenic E. coli of porcine origin using a microplate serial dilution method. Bioautography, also with p-iodonitrotetrazolium violet as growth indicator was used to view the number of bioactive compounds in each extract. In vitro toxicity of extracts was determined against Caco-2 cells using the 3-(4,5-dimethythiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay. The antimicrobial susceptibility of E. coli isolates was tested on a panel of antimicrobials using the Kirby-Bauer agar diffusion method while the anti-adherence mechanism was evaluated using a Caco-2 cell enterocyte anti-adhesion model.

RESULTS

The MIC of the extracts ranged from 0.07-0.14 mg/mL with S. legatii having the best mean MIC (0.05 mg/mL). Bioautography revealed at least two active bands in each plant extract. The 50% lethal concentration (LC₅₀) values ranged between 0.03-0.66 mg/mL. Eugenia zeyheri least cytotoxic (LC₅₀ = 0.66 mg/ml) while E. natalitia had the highest cytotoxicity (LC₅₀ = 0.03 mg/mL). All the bacteria were completely resistant to doxycycline and colistin sulphate and many of the plant extracts significantly reduced adhesion of E. coli to Caco-2 cells.

CONCLUSIONS

The extracts of the plants had good antibacterial activity as well as a protective role on intestinal epithelial cells against enterotoxigenic E. coli bacterial adhesion. This supports the potential use of these species in limiting infection causes by E. coli. Some of these plants or extracts may be useful as phytogenic feed additives but it has to be investigated by animal feed trials.

Immunogenicity of Pigeon Circovirus Recombinant Capsid Protein in Pigeons

Pigeon circovirus (PiCV) is the most frequently diagnosed virus in pigeons and is thought to be one of the causative factors of a complex disease called the young pigeon disease syndrome (YPDS). The development of a vaccine against this virus could be a strategy for YPDS control. Since laboratory culture of PiCV is impossible, its recombinant capsid protein (rCP) can be considered as a potential antigen candidate in sub-unit vaccines. The aim of this basic research was to evaluate the immune response of pigeons to PiCV rCP. Sixty six-week-old carrier pigeons were divided into two groups (experimental immunized with PiCV rCP mixed with an adjuvant, and control immunized with an adjuvant only), and immunized twice in a 21-day interval. On the day of immunization and on two, 23, 39, and 46 days post first immunization (dpv), samples of blood, spleen, and bursa of Fabricius were collected from six birds from each group to examine anti-PiCV rCP IgY, anti-PiCV rCP IgY-secreting B cells (SBC), IFN-γ gene expression, and percentage of T CD3⁺, CD4⁺, CD8⁺, and B IgM⁺ lymphocytes. The results indicated a correct immune response to PiCV rCP both in humoral and cell-mediated immunity, which was manifested by seroconversion since 23 dpv, by a significantly higher anti-PiCV rCP IgY-SBC number on two and 23 dpv, and significantly higher IFN-γ gene expression since two dpv. There were no significant differences or trends noted between particular T and B lymphocyte subpopulations. To conclude, PiCV rCP may be deemed immunogenic and could be considered as an antigen candidate in sub-unit vaccines against PiCV infections in pigeons.