Co-administration of avian influenza virus H5 plasmid DNA with chicken IL-15 and IL-18 enhanced chickens immune responses

Enhance immune response to H9 AIV DNA vaccine based on polygene expression and DGL nanoparticle encapsulation

DNA vaccination has great potential to treat or prevent avian influenza pandemics, but the technique may be limited by low immunogenicity and gene delivery in clinical testing. Here, to improve the immune efficacy of DNA vaccines against avian influenza, we prepared and tested the immunogenicity of 4 recombinant DNA vaccines containing 2 or 3 AIV antigens. The results revealed that chickens and mice immunized with plasmid DNA containing 3 antigens (HA gene from H9N2, and NA and HA genes from H5N1) exhibited a robust immune response than chickens and mice immunized with plasmid DNAs containing 2 antigenic genes. Subsequently, this study used pβH9N1SH5 as a model antigen to study the effect of dendritic polylysine (DGL) nanoparticles as a gene delivery system and adjuvant on antigen-specific immunity in mice models. At a ratio of 1:3 DGL/pβH9N1SH5 (w/w), the pβH9N1SH5/DGL NPs showed excellent physical and chemical properties, induced higher levels of HI antibodies, and larger CD3+/CD4+ T lymphocyte and CD3+/CD8+ T lymphocyte population, as well as the production of cytokines, namely, interferon (IFN)-γ, interleukin (IL)-2 compared with the naked pβH9N1SH5. Therefore, multiantigen gene expression methods using DGL as a delivery system may have broad application prospects in gene therapy.

Evolution of developmental and comparative immunology in poultry: The regulators and the regulated

Avian has a unique immune system that evolved in response to environmental pressures in all aspects of innate and adaptive immune responses, including localized and circulating lymphocytes, diversity of immunoglobulin repertoire, and various cytokines and chemokines. All of these attributes make birds an indispensable vertebrate model for studying the fundamental immunological concepts and comparative immunology. However, research on the immune system in birds lags far behind that of humans, mice, and other agricultural animal species, and limited immune tools have hindered the adequate application of birds as disease models for mammalian systems. An in-depth understanding of the avian immune system relies on the detailed studies of various regulated and regulatory mediators, such as cell surface antigens, cytokines, and chemokines. Here, we review current knowledge centered on the roles of avian cell surface antigens, cytokines, chemokines, and beyond. Moreover, we provide an update on recent progress in this rapidly developing field of study with respect to the availability of immune reagents that will facilitate the study of regulatory and regulated components of poultry immunity. The new information on avian immunity and available immune tools will benefit avian researchers and evolutionary biologists in conducting fundamental and applied research.

Strategies for enhancing immunity against avian influenza virus in chickens: A review

Poultry infection with avian influenza viruses (AIV) is a continuous source of concern for poultry production and human health. Uncontrolled infection and transmission of AIV in poultry increases the potential for viral mutation and reassortment, possibly resulting in the emergence of zoonotic viruses. To this end, implementing strategies to disrupt the transmission of AIVs in poultry, including a wide array of traditional and novel methods, is much needed. Vaccination of poultry is a targeted approach to reduce clinical signs and shedding in infected birds. Strategies aimed at enhancing the effectiveness of AIV vaccines are multi-pronged and include methods directed towards eliciting immune responses in poultry. Strategies include producing vaccines of greater immunogenicity via vaccine type and adjuvant application and increasing bird responsiveness to vaccines by modification of the gastrointestinal tract (GIT) microbiome and dietary interventions. This review provides an in-depth discussion of recent findings surrounding novel AIV vaccines for poultry, including reverse genetics vaccines, vectors, protein vaccines and virus like particles, highlighting their experimental efficacy among other factors such as safety and potential for use in the field. In addition to the type of vaccine employed, vaccine adjuvants also provide an effective way to enhance AIV vaccine efficacy, therefore, research on different types of vaccine adjuvants and vaccine adjuvant delivery strategies is discussed. Finally, the poultry gastrointestinal microbiome is emerging as an important factor in the effectiveness of prophylactic treatments. In this regard, current findings on the effects of the chicken GIT microbiome on AIV vaccine efficacy are summarized here.

Gut Microbiota Dysbiosis Aggravates Mycoplasma gallisepticum Colonization in the Chicken Lung

Mycoplasma gallisepticum (MG) is the pathogen that causes chronic respiratory diseases in chickens. Gut microbiota plays an important role in maintaining body health and resisting respiratory infection, but the correlation between gut microbiota and MG infection is poorly defined. Therefore, in this study, the correlation between gut microbiota and MG infection was explored by disturbing gut microbiota in chickens with antibiotic cocktail. The results showed that the gut microbiota dysbiosis impairs pulmonary immune response against MG infection. It has been noted that MG colonization in the lung was significantly increased following gut microbiota dysbiosis, and this could be reversed by intranasally administrated toll-like receptor 2 (TLR2) ligand, recombinant chicken IL-17 protein or recombinant chicken granulocyte-macrophage colony-stimulating factor (GM-CSF) protein. In addition, the levels of short-chain fatty acids (SCFAs) and vitamin A were significantly reduced in gut microbiota dysbiosis group, however, butyric acid or vitamin A as feed additives promoted MG clearance in the lung of gut microbiota dysbiosis group via increasing TLR2/IL17/GM-CSF and host defense peptides genes expression. The present study revealed an important role of gut microbiota in the defense against MG colonization in the lung of chicken.

Transcriptomic analysis of chicken immune response to infection of different doses of Newcastle disease vaccine

Newcastle disease virus (NDV) is a contagious poultry paramyxovirus, leading to substantial economic losses to the poultry industry. Here, RNA-seq was carried out to investigate the altered expression of immune-related genes in chicken thymus within 96 h in response to NDV infection. In NDV-infected chicken thymus tissues, comparative transcriptome analysis revealed 1386 differentially expressed genes (DEGs) at 24 h with 989 up- and 397 down-regulated genes, 728 DEGs at 48 h with 567 up- and 161 down-regulated genes, 1514 DEGs at 72 h with 1016 up- and 498 down-regulated genes, and 1196 DEGs at 96 h with 522 up- and 674 down-regulated genes, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these candidate targets mainly participate in biological processes or biochemical, metabolic and signal transduction processes. Notably, there is large enrichment in biological processes, cell components and metabolic processes, which may be related to NDV pathogenicity. In addition, the expression of five immune-related DEGs identified by RNA-seq was validated by quantitative real-time polymerase chain reaction (qRT-PCR). Our results indicated that the expression levels of AvBD5, IL16, IL22 and IL18R1 were obviously up-regulated, and Il-18 expression was also changed, but not significantly, which play key roles in the defense against NDV. Overall, we identified several candidate targets that may be involved in the regulation of NDV infection, which provide new insights into the complicated regulatory mechanisms of virus-host interactions, and explore new strategies for protecting chickens against the virus.

Lactobacillus fermentum Administration Modulates Cytokine Expression and Lymphocyte Subpopulation Levels in Broiler Chickens Challenged with Campylobacter coli

This investigation was performed to assess the supplementation of probiotics on cytokine expression and lymphocyte subpopulation in Campylobacter coli challenged chickens. Thirty-six individuals were equally separated into four experimental treatments: C = untreated chickens, LB = probiotic control (Lactobacillus fermentum), Cc = Campylobacter-challenged control, LBCc = probiotic + Cc. All chicks were slaughtered and cecum samples were collected on day 4 postinfection. Gene expression analysis, using reverse transcription quantitative PCR (RT-qPCR), revealed significant differences in cytokine transcript expression between untreated and probiotic-treated chickens. In addition, flow cytometry was used to quantitate the levels of lymphocyte subpopulations. Principal component analysis showed that probiotic administration induced an overall downregulation of cytokine expression. C. coli exposure provoked a similar response to that of L. fermentum but to a lesser extent. Colonization of C. coli in the presence of the probiotic evoked a complex response with an upregulation of some type II cytokines, including interleukin IL-4 and IL-13, which could explain the increased presence of antibodies in both lamina propria and epithelium. Moreover, despite that the percentage of CD8 intraepithelial lymphocytes (IELs) was found to be higher, downregulation of proinflammatory cytokines IL-15, IL-16, and interferon γ was observed. This suggests that the detected CD8 are not effector cells but induced IELs, which release antimicrobial peptides, and are ready to be primed upon encountering antigen. These outcomes demonstrate that probiotic administration promotes a humoral response to a C. coli infection while dampening any potential inflammation mediated by effector T cells in 1-week-old chicks.

Co-infection of Mycoplasma gallisepticum and Escherichia coli Triggers Inflammatory Injury Involving the IL-17 Signaling Pathway

Mycoplasma gallisepticum and Escherichia coli are well known respiratory disease-inducing pathogens. Previous studies have reported that co-infection by MG and E.coli causes significant economic loss in the poultry industry. In order to assess the respiratory toxicity of co-infection in chicken lung, we established a co-infection model to investigate changes in the inflammatory cytokines, lung tissue structure, and transcriptome profiles of chicken lung. The results showed that co-infection caused a wider range of immune damage and more severe tissue lesions than single-pathogen infection. Differentially expressed gene (DEG) analysis indicated that 3,115/1,498/1,075 genes were significantly expressed among the three infection groups, respectively. Gene ontology and KEGG analysis showed genes enriched in response to immune response, cytokine-cytokine receptor interaction, and inflammation-related signaling pathways. Among these pathways, IL-17 signaling was found to be significantly enriched only in co-infection. The expression of IL-17C, CIKS, TRAF6, NFκB, C/EBPβ, and inflammatory chemokines were significantly up-regulated in response to co-infection. Taken together, we concluded that co-infection increased the expression of inflammatory chemokines in lungs through IL-17 signaling, leading to cilia loss and excessive mucus secretion. These results provide new insights into co-infection and reveal target proteins for drug therapy.

Sequential DNA immunization of chickens with bivalent heterologous vaccines induce highly reactive and cross-specific antibodies against influenza hemagglutinin

Vaccines against avian influenza are mostly based on hemagglutinin (HA), which is the main antigen of this virus and a target for neutralizing antibodies. Traditional vaccines are known to be poorly efficient against newly emerging strains, which is an increasing worldwide problem for human health and for the poultry industry. As demonstrated by research and clinical data, sequential exposure to divergent influenza HAs can boost induction of universal antibodies which recognize conserved epitopes. In this work, we have performed sequential immunization of laying hens using monovalent or bivalent compositions of DNA vaccines encoding HAs from distant groups 1 and 2 (H5, H1, and H3 subtypes, respectively). This strategy gave promising results, as it led to induction of polyclonal antibodies against HAs from both groups. These polyclonal antibodies showed cross-reactivity between different HA strains in ELISA, especially when bivalent formulations were used for immunization of birds. However, cross-reactivity of antibodies induced against H3 and H5 HA subtypes was rather limited against each other after homologous immunization. Using a cocktail of HA sequences and/or sequential DNA vaccination with different strains presents a good strategy to overcome the limited effectiveness of vaccines and induce broader immunity against avian influenza. Such a strategy could be adapted for vaccinating laying hens or parental flocks of different groups of poultry.

Inoculation of fowlpox viruses coexpressing avian influenza H5 and chicken IL-15 cytokine gene stimulates diverse host immune responses

Fowlpox virus (FWPV) has been used as a recombinant vaccine vector to express antigens from several important avian pathogens. Attempts have been made to improve vaccine strains induced-host immune responses by coexpressing cytokines. This study describes the construction of recombinant FWPV (rFWPV) strain FP9 and immunological responses in specific-pathogen-free (SPF) chickens, co-expressing avian influenza virus (AIV) H5 of A/Chicken/Malaysia/5858/2004, and chicken IL-15 cytokine genes. Expression of H5 (50 kD) was confirmed by western blotting. Anti-H5 antibodies, which were measured by the haemagglutinin inhibition test, were at the highest levels at Week 3 post-inoculation in both rFWPV/H5- and rFWPV/H5/IL-15-vaccinated chickens, but decreased to undetectable levels from Week 5 onwards. CD3+/CD4+ or CD3+/CD8+T cell populations, assessed using flow cytometry, were significantly increased in both WT FP9- and rFWPV/H5-vaccinated chickens and were also higher than in rFWPV/H5/IL-15- vaccinated chickens, at Week 2. Gene expression analysis using real time quantitative polymerase chain reaction (qPCR) demonstrated upregulation of IL-15 expression in all vaccinated groups with rFWPV/H5/IL-15 having the highest fold change, at day 2 (117±51.53). Despite showing upregulation, fold change values of the IL-18 expression were below 1.00 for all vaccinated groups at day 2, 4 and 6. This study shows successful construction of rFWPV/H5 co-expressing IL-15, with modified immunogenicity upon inoculation into SPF chickens.

IL-15 enhances cross-reactive antibody recall responses to seasonal H3 influenza viruses in vitro

Background: Recently, several human monoclonal antibodies that target conserved epitopes on the stalk region of influenza hemagglutinin (HA) have shown broad reactivity to influenza A subtypes. Also, vaccination with recombinant chimeric HA or stem fragments from H3 influenza viruses induce broad immune protection in mice and humans. However, it is unclear whether stalk-binding antibodies can be induced in human memory B cells by seasonal H3N2 viruses.

Methods: In this study, we recruited 13 donors previously exposed to H3 viruses, the majority (12 of 13) of which had been immunized with seasonal influenza vaccines. We evaluated plasma baseline strain-specific and stalk-reactive anti-HA antibodies and B cell recall responses to inactivated H3N2 A/Victoria/361/2011 virus in vitro using a high throughput multiplex (mPlex-Flu) assay.

Results: Stalk-reactive IgG was detected in the plasma of 7 of the subjects. Inactivated H3 viral particles rapidly induced clade cross-reactive antibodies in B cell cultures derived from all 13 donors. In addition, H3 stalk-reactive antibodies were detected in culture supernatants from 7 of the 13 donors (53.8%).  H3 stalk-reactive antibodies were also induced by H1 and H7 subtypes. Interestingly, broadly cross-reactive antibody recall responses to H3 strains were also enhanced by stimulating B cells in vitro with CpG ₂₀₀₆ ODN in the presence of IL-15. H3 stalk-reactive antibodies were detected in  CpG ₂₀₀₆ ODN + IL-15 stimulated B cell cultures derived from 12 of the 13 donors (92.3%), with high levels detected in cultures from 7 of the 13 donors.

Conclusions: Our results demonstrate that stalk-reactive antibody recall responses induced by seasonal H3 viruses and CpG ₂₀₀₆ ODN can be enhanced by IL-15.

Blocking NF-κB Is Essential for the Immunotherapeutic Effect of Recombinant IL18 in Pancreatic Cancer

PURPOSE

We sought to find new immune-based treatments for pancreatic cancer.

EXPERIMENTAL DESIGN

We detected IL18 expression in plasma and specimens from patients with pancreatic cancer. We then investigated whether IL18 had a therapeutic effect for pancreatic cancer in vitro and in vivo and any underlying mechanisms.

RESULTS

Higher plasma IL18 was associated with longer overall survival (OS), but higher IL18 in pancreatic cancer tissues was associated with shorter OS and increased invasion and metastasis. Recombinant IL18 alone had no antitumor effect in the syngeneic mice with orthotopically transplanted tumors and promoted tumors in immunocompromised mice; it also facilitated immune responses in vitro and in vivo by augmenting the activity of cytotoxic T cells and NK cells in peripheral blood and lymph nodes. However, IL18 promoted the proliferation and invasion of pancreatic cancer cells, in vitro and in vivo, through the NF-κB pathway. Nevertheless, by coadministrating IL18 with BAY11-7082, an NF-κB inhibitor, we were able to prevent the procancerous effects of IL18 and prolong the survival time of the mice.

CONCLUSIONS

IL18 has both cancer-promoting and cancer-suppressing functions. Although its single-agent treatment has no therapeutic effect on pancreatic cancer, when combined with the NF-κB pathway inhibitor, IL18 improved survival in a murine pancreatic cancer model. Our study implies the possibility of a combinational immunotherapy that uses IL18 and targets NF-κB pathway. Clin Cancer Res; 22(23); 5939-50. ©2016 AACR.

Vaccines against influenza A viruses in poultry and swine: Status and future developments

Influenza A viruses are important pathogens with a very broad host spectrum including domestic poultry and swine. For preventing clinical disease and controlling the spread, vaccination is one of the most efficient tools. Classical influenza vaccines for domestic poultry and swine are conventional inactivated preparations. However, a very broad range of novel vaccine types ranging from (i) nucleic acid-based vaccines, (ii) replicon particles, (iii) subunits and virus-like particles, (iv) vectored vaccines, or (v) live-attenuated vaccines has been described, and some of them are now also used in the field. The different novel approaches for vaccines against avian and swine influenza virus infections are reviewed, and additional features like universal vaccines, novel application approaches and the "differentiating infected from vaccinated animals" (DIVA)-strategy are summarized.

A eukaryotic expression plasmid carrying chicken interleukin-18 enhances the response to newcastle disease virus vaccine

Interleukin-18 (IL-18) is an important cytokine involved in innate and acquired immunity. In this study, we cloned the full-length chicken IL-18 (ChIL-18) gene from specific-pathogen-free (SPF) chicken embryo spleen cells and provided evidence that the ChIL-18 gene in a recombinant plasmid was successfully expressed in chicken DT40 cells. ChIL-18 significantly enhanced gamma interferon (IFN-γ) mRNA expression in chicken splenocytes, which increased IFN-γ-induced nitric oxide (NO) synthesis by macrophages. The potential genetic adjuvant activity of the ChIL-18 plasmid was examined in chickens by coinjecting ChIL-18 plasmid and inactivated Newcastle disease virus (NDV) vaccine. ChIL-18 markedly elevated serum hemagglutination inhibition (HI) titers and anti-hemagglutinin-neuraminidase (anti-HN)-specific antibody levels, induced the secretion of both Th1- (IFN-γ) and Th2- (interleukin-4) type cytokines, promoted the proliferation of T and B lymphocytes, and increased the populations of CD3(+) T cells and their subsets, CD3(+) CD4(+) and CD3(+) CD8(+) T cells. Furthermore, a virus challenge revealed that ChIL-18 contributed to protection against Newcastle disease virus challenge. Taken together, our data indicate that the coadministration of ChIL-18 plasmid and NDV vaccine induces a strong immune response at both the humoral and cellular levels and that ChIL-18 is a novel immunoadjuvant suitable for NDV vaccination.

Astragalus Polysaccharide Protects Astrocytes from Being Infected by HSV-1 through TLR3/NF-κB Signaling Pathway

Astragalus polysaccharide (APS) is the most immunoreactive substance in Astragalus. APS can regulate the body's immunity and is widely used in many immune related diseases. However, till now, there is little information about its contribution to the protection of astrocytes infected by virus. Toll-like receptor 3 (TLR3) is a key component of the innate immune system and has the ability to detect virus infection and trigger host defence responses. This study was undertaken to elucidate the protective effect of APS on herpes simplex virus (HSV-1) infected astrocytes and the underlying mechanisms. The results showed that APS protected the astrocytes from HSV-1 induced proliferation inhibition along with increasing expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) markedly. Moreover, APS significantly promoted the expression of Toll-like receptor 3 (TLR3) and the activation of nuclear factor-κB (NF-κB) in astrocytes. In addition, while astrocytes were pretreated with TLR3 antibody before adding HSV-1 and APS, the expression of TLR3, TNF-α, and IL-6 and the activation of NF-κB decreased sharply. These results indicate that APS can protect astrocytes by promoting immunological function provoked by HSV-1 through TLR3/NF-κB pathway.

Antibody and T cell responses induced in chickens immunized with avian influenza virus N1 and NP DNA vaccine with chicken IL-15 and IL-18

We had examined the immunogenicity of a series of plasmid DNAs which include neuraminidase (NA) and nucleoprotein (NP) genes from avian influenza virus (AIV). The interleukin-15 (IL-15) and interleukin-18 (IL-18) as genetic adjuvants were used for immunization in combination with the N1 and NP AIV genes. In the first trial, 8 groups of chickens were established with 10 specific-pathogen-free (SPF) chickens per group while, in the second trial 7 SPF chickens per group were used. The overall N1 enzyme-linked immunosorbent assay (ELISA) titer in chickens immunized with the pDis/N1+pDis/IL-15 was higher compared to the chickens immunized with the pDis/N1 and this suggesting that chicken IL-15 could play a role in enhancing the humoral immune response. Besides that, the chickens that were immunized at 14-day-old (Trial 2) showed a higher N1 antibody titer compared to the chickens that were immunized at 1-day-old (Trial 1). Despite the delayed in NP antibody responses, the chickens co-administrated with IL-15 were able to induce earlier and higher antibody response compared to the pDis/NP and pDis/NP+pDis/IL-18 inoculated groups. The pDis/N1+pDis/IL-15 inoculated chickens also induced higher CD8+ T cells increase than the pDis/N1 group in both trials (P<0.05). The flow cytometry results from both trials demonstrated that the pDis/N1+pDis/IL-18 groups were able to induce CD4+ T cells higher than the pDis/N1 group (P<0.05). Meanwhile, pDis/N1+pDis/IL-18 group was able to induce CD8+ T cells higher than the pDis/N1 group (P<0.05) in Trial 2 only. In the present study, pDis/NP was not significant (P>0.05) in inducing CD4+ and CD8+ T cells when co-administered with the pDis/IL-18 in both trials in comparison to the pDis/NP. Our data suggest that the pDis/N1+pDis/IL-15 combination has the potential to be used as a DNA vaccine against AIV in chickens.

Modulation of Humoral and Cell-Mediated Immunity Against Avian Influenza and Newcastle Disease Vaccines by Oral Administration of Salmonella enterica Serovar Typhimurium Expressing Chicken Interleukin-18

Interleukin-18 (IL-18) has been known to induce interferon-γ (IFN-γ) production and promote Th1 immunity. Although mammalian IL-18 has been characterized in great detail, the properties and application of chicken IL-18 remain largely uninvestigated as of yet. In this study, we evaluated the immunomodulatory properties of Salmonella enterica serovar Typhimurium expressing chicken interleukin-18 (chIL-18) on immune responses induced by avian influenza (AI) and Newcastle disease (ND) vaccines. After oral administration of S. enterica serovar Typhimurium expressing chIL-18, chickens were vaccinated intramuscularly with the recommended dose of either inactivated AI H9N2 vaccine or ND (B1 strain) vaccine. Chickens receiving a primary vaccination were boosted using the same protocol 7 days later. Humoral and cell-mediated immune responses were evaluated in terms of HI antibody titers and proliferation and mRNA expression of IFN-γ and IL-4 of peripheral blood mononuclear cells (PBMC) in response to specific antigen stimulation. According to our results, oral administration of S. enterica serovar Typhimurium expressing chIL-18 induced enhanced humoral and Th1-biased cell-mediated immunity against AI and ND vaccines, compared to that of chickens received S. enterica serovar Typhimurium harboring empty vector. Therefore, we conclude that our proposed vaccination regimen using inactivated AI and ND viruses along with oral administration of S. enterica serovar Typhimurium expressing chIL-18 may provide a novel approach in protecting chicken from currently circulating AI and ND virus strains.