Porcine-specific CpG-oligodeoxynucleotide activates B-cells and increases the expression of MHC-II molecules on lymphocytes

Intestinal single-cell atlas reveals novel lymphocytes in pigs with similarities to human cells

Lymphocytes can heavily influence intestinal health, but resolving intestinal lymphocyte function is challenging as the intestine contains a vastly heterogeneous mixture of cells. Pigs are an advantageous biomedical model, but deeper understanding of intestinal lymphocytes is warranted to improve model utility. Twenty-six cell types were identified in the porcine ileum by single-cell RNA sequencing and further compared with cells in human and murine ileum. Though general consensus of cell subsets across species was revealed, some porcine-specific lymphocyte subsets were identified. Differential tissue dissection and in situ analyses conferred spatial context, revealing similar locations of lymphocyte subsets in Peyer's patches and epithelium in pig-to-human comparisons. Like humans, activated and effector lymphocytes were abundant in the ileum but not periphery of pigs, suggesting tissue-specific and/or activation-associated gene expression. Gene signatures for peripheral and ileal innate lymphoid cells newly discovered in pigs were defined and highlighted similarities to human innate lymphoid cells. Overall, we reveal novel lymphocyte subsets in pigs and highlight utility of pigs for intestinal research applications.

The anti-influenza M2e antibody response is promoted by XCR1 targeting in pig skin

XCR1 is selectively expressed on a conventional dendritic cell subset, the cDC1 subset, through phylogenetically distant species. The outcome of antigen-targeting to XCR1 may therefore be similar across species, permitting the translation of results from experimental models to human and veterinary applications. Here we evaluated in pigs the immunogenicity of bivalent protein structures made of XCL1 fused to the external portion of the influenza virus M2 proton pump, which is conserved through strains and a candidate for universal influenza vaccines. Pigs represent a relevant target of such universal vaccines as pigs can be infected by swine, human and avian strains. We found that cDC1 were the only cell type labeled by XCR1-targeted mCherry upon intradermal injection in pig skin. XCR1-targeted M2e induced higher IgG responses in seronegative and seropositive pigs as compared to non-targeted M2e. The IgG response was less significantly enhanced by CpG than by XCR1 targeting, and CpG did not further increase the response elicited by XCR1 targeting. Monophosphoryl lipid A with neutral liposomes did not have significant effect. Thus altogether M2e-targeting to XCR1 shows promises for a trans-species universal influenza vaccine strategy, possibly avoiding the use of classical adjuvants.

Organic barn dust extract exposure impairs porcine macrophage function in vitro: implications for respiratory health

Respiratory diseases are responsible for a significant amount of animal morbidity and mortality in the swine industry, including the majority of nursery and grower/finisher deaths. Innate immunity, including the maintenance of lung macrophage health and function, is an important defense mechanism against respiratory pathogens and their associated losses. Chronic exposure of swine industry workers to airborne barn dust results in significant predisposition to airway diseases and impairment of alveolar macrophage (AMφ) function. Because of their importance in maintaining normal respiratory function, this study was designed to evaluate the impact of barn dust on swine macrophages. As measures of macrophage function, we evaluated the activation of NF-κB, cytokine production, cell surface marker expression and the phagocytic and antibacterial capabilities of porcine macrophages after in vitro exposure to an organic swine barn dust extract (ODE). ODE treatment induced AMφ secretion of both pro- and anti-inflammatory cytokines, suggesting a complex activation profile. Additionally, ODE induced expression of genes (TLR2, NOD2) involved in sensing Gram-positive bacteria, a major component of barn dust. ODE exposure also enhanced the expression of several cell surface markers of activation, including a receptor for the porcine reproductive and respiratory syndrome virus. Moreover, two key functions of AMϕ, phagocytosis and bacterial killing, were impaired after exposure to ODE. Treatment with ODE for the first 72 h of differentiation also inhibited the ability of monocyte-derived macrophages to translocate NF-κB to the nucleus following endotoxin stimulation. Taken together, these results demonstrate, for the first time, that organic dust extract exposure negatively affects pig macrophage activation and function, potentially enhancing host susceptibility to a variety of respiratory infections.

Enhanced immunogenicity induced by an alphavirus replicon-based pseudotyped baculovirus vaccine against porcine reproductive and respiratory syndrome virus

Pseudotyped baculovirus has emerged as a promising vector for vaccine development and gene therapy. Alphaviruses, such as Semliki Forest virus (SFV), have also received considerable attention for use as expression vectors because of their self-replicating properties. In this study, pseudotyped baculovirus containing the hybrid cytomegalovirus (CMV) promoter/SFV replicon was used as a vector to co-express the GP5 and M proteins of porcine reproductive and respiratory syndrome virus (PRRSV). The immunogenicity of the resulting recombinant baculovirus (BV-SFV-5m6) was compared with the pseudotyped baculovirus vaccine (BV-CMV-5m6), in which the expression of GP5 and M were driven by the CMV promoter only. In vitro, BV-SFV-5m6 exhibited enhanced expression of foreign proteins and also caused apoptosis in transduced cells. After immunization in BALB/c mice, BV-SFV-5m6 induced strong GP5-specific ELISA antibodies and neutralizing antibodies against homologous and heterologous viruses, along with dose sparing. Further analysis of the cell-mediated immune response showed that BV-SFV-5m6 elicited a Th1-dominant immune response that was greater than that elicited by BV-CMV-5m6. Taken together, the results of this study indicate that a baculovirus containing the hybrid CMV promoter/alphavirus replicon can be utilized as an alternative strategy to develop an efficacious vaccine against PRRSV infection.

Plasmid containing CpG oligodeoxynucleotides can augment the immune responses of pigs immunized with porcine reproductive and respiratory syndrome killed virus vaccine

Porcine reproductive and respiratory syndrome virus (PRRSV), the causative agent of porcine reproductive and respiratory syndrome (PRRS), causes serious health problems in swine, resulting in great economic losses to the swine industry worldwide. The porcine reproductive and respiratory syndrome (PRRS) killed virus (KV) vaccine has been widely used in China but has been linked with side effects in pigs and only partial protection. A few studies have demonstrated the immunostimulatory adjuvant effects of the synthetic CpG oligodeoxynucleotide (ODN) motifs in humans and animals. In this study, the adjuvant efficacy and the protective effects of recombinant plasmid containing CpG ODN, in combination with PRRS KV vaccine against PRRSV were evaluated. The concentration of PRRSV-specific antibodies and cytokines and the clinical parameters (body temperature, weight gain and behavior) on the challenge and post-challenge virological profiles (virus distribution in tissues and virus titers in serum at autopsy) were investigated to define the immune responses of pigs. Our findings indicated that the immune responses of the pigs immunized with plasmid containing CpG ODN and PRRS KV vaccine were stronger than those induced by PRRS KV vaccine or PBS alone. Furthermore, the protection ratios, PRRSV titers in serum samples and virus tissue distribution, all demonstrated that the plasmid containing CpG ODN could augment the immune responses and improve the protective effect of PRRSV vaccination.

All three classes of CpG ODNs up-regulate IP-10 gene in pigs

The analysis of CpG ODN induced innate immune responses in different animal species has shown substantial similarities and differences in levels and types of induced cytokines profile. The objectives of these studies were to identify innate immune biomarkers activated by three classes of CpG ODNs in pigs. For this purpose, we investigated the kinetics of innate immune responses in immune cells from pigs following in vitro and in vivo stimulation with CpG ODNs. The mRNA expression of cytokine and chemokine genes were assayed by SYBR green based quantitative real time PCR. A-class CpG ODN induced significant but transient levels of IFN-gamma, IL-12 (P40), IL-6, IL-4 and TNF-alpha mRNA, C-class CpG ODN induced significant level of IFN-gamma, IFN-alpha and IL-12 mRNA and the lowest level of IL-4 (Th-2 type) mRNA. A very low level of some cytokines stimulation was observed by GC ODNs. It is noteworthy, that IL-12 (P35) mRNA was significantly stimulated by B-class GpC ODN 7909. Interestingly, all classes of CpG ODNs induced significant level of IP-10 at 12h post stimulation. These in vitro and in vivo observations suggest that interferon-gamma inducible protein 10 (IP-10) may be a reliable biomarker for immune activity induced by CpG ODNs in pigs.

Phosphorothioate oligodeoxyribonucleotides induce in vitro proliferation of chicken B-cells

The study aimed to evaluate short synthetic oligodeoxyribonucleotides (ODN) as inducers of proliferation of chicken peripheral blood mononuclear cells (PBMC) and to identify the proliferating cells. A panel of different ODN; with phosphodiester and/or phosphorothioate backbone, with and without CpG-motifs, was therefore assessed for in vitro induction of proliferation. Six complete phosphorothioate ODN induced proliferation of PBMC while the complete phosphodiester or chimeric phosphodiester/phosphorohiate ODN did not. Moreover, CpG-motifs were not essential for induction of proliferation as responses to CpG-ODN were similar to those of their GpC controls. Two stimulatory phosphorothioate ODN were also used in phosphodiester form. In this comparison, only the phosphorothioate ODN were active despite the identical nucleotide sequences of their phosphodiester counterparts. In order to deliver DNA to the cytoplasm and decrease degradation of ODN by nucleases, stimulating as well as inactive ODN were treated with lipofectin prior to induction. However, proliferative responses were not influenced by lipofectin treatment and in analogy, none of the inactive ODN induced proliferation after lipofectin treatment. Among PBMC, ODN-responding cells were identified as predominantly Bu-1, immunoglobulin and major histocompatibility complex class II expressing cells, while CD3 expressing cells were not responding. Using magnetic cell separation of Bu-1 expressing cells prior to culture it was found that Bu-1 depleted cells did not proliferate upon ODN stimulation while the Bu-1 enriched cells were able to proliferate upon this stimulus. Taken together, among ODN in the present panel, only phosphorothioate ODN induced proliferation of PBMC. Responses were induced regardless of the presence of CpG-motifs and were not influenced by addition of lipofectin. Amid the chicken PBMC, predominantly cells of a B-cell phenotype proliferated in response to ODN stimulation and they were able to respond to this stimulus without the presence of other cell types.

Molecular characterization and expression analysis of MHC class II alpha and beta genes in large yellow croaker (Pseudosciaena crocea)

MHC class II molecules play an important role in the activation of CD4(+) T cells, which are the central orchestrating cells of an immune response. Here, we report the cloning of MHC class II alpha and beta cDNAs from large yellow croaker (Pscr-DAAs and Pscr-DAB) by expressed sequence tags analysis and RACE-PCR techniques. Three different class II alpha and two class II beta sequences were obtained from spleens of two individual fish. Each of the three class II alpha sequences encodes a polypeptide of 239 amino acids while the two class II beta cDNA sequences encode for a protein of 249 aa. All the characteristic features of MHC class II chain structure could be identified in the deduced proteins of three class II alpha and two class II beta sequences, including the leader peptide, alpha1/beta1 and alpha2/beta2 domains, connecting peptide and transmembrane and cytoplasmic regions, as well as conserved cysteines and N-glycosylation site. RT-PCR analysis showed that MHC class II alpha and beta mRNAs were broadly expressed in various tissues examined, although at different levels. Upon stimulation with inactivated trivalent bacterial vaccine or polyinosinic polycytidylic acid (poly(I:C)), the expression levels of both alpha and beta genes were obviously up-regulated in intestine, kidney and spleen. Real-time PCR analysis demonstrated that the expression levels of class II alpha and beta were quickly up-regulated in spleen, kidney, and intestine at 12 h after induction with poly(I:C), while their expression levels significantly increased at 48 h upon immunization with bacterial vaccine, indicating that the up-regulation of both class II alpha and beta expression was induced by bacterial vaccine or poly(I:C) at the early phase of induction, and that class II alpha and beta transcripts were quicker up-regulated by poly I:C than by bacterial vaccine.

Adjuvants for porcine reproductive and respiratory syndrome virus vaccines

This review deals with present and past efforts in utilization of vaccine adjuvants for porcine reproductive and respiratory syndrome virus (PRRSV) vaccines. PRRSV vaccines elicit delayed and weak cell-mediated immune (CMI) and antibody responses after vaccination. Several kinds of vaccine adjuvants have been utilized to accelerate and magnify immune responses to PRRSV vaccines. These adjuvants include cytokines, chemical reagents, and bacterial products. Of 11 vaccine adjuvants tested, five (i.e. interleukin-2 (IL-2), IL-12, interferon alpha (IFNalpha), polyinosinic and polycytidylic acid, and cytidine-phosphate-guanosine oligodeoxynucleotides (CpG ODN)) significantly enhance CMI response to PRRSV vaccines. The response is characterized by proliferation, cytotoxicity, and IFNgamma secretion of peripheral blood mononuclear cells or T cells in response to recall PRRSV antigens in vitro. Two (i.e. CpG ODN and cholera toxin) significantly enhance PRRSV-specific antibody response after vaccination. Two (i.e. IL-2 and CpG ODN) significantly enhance protective efficacy of PRRSV vaccines in challenge models. Improvement of immune responses to PRRSV vaccines should focus in future studies on assessing more vaccine adjuvants for their efficiency in enhancing both CMI and antibody responses and on identifying PRRSV components and strategies that down-modulate pig immune responses in order to devise vaccine adjuvants that can regulate such strategies of the virus.

Membrane markers of the immune cells in swine: an update

Besides their breeding value, swine are increasingly used as biomedical models. As reported in three international swine clusters of differentiation (CD) workshops and in the animal homologue section of the last workshop for the determination of human leukocyte differentiation antigens (HLDA 8), characterisation of leukocyte surface antigens by monoclonal antibodies and other molecular studies have determined the cell lineages and blood leukocyte subsets implicated in the immune response, including cell adhesion molecules involved in cell trafficking. This review focusses on the current state of knowledge of porcine leukocyte differentiation and major histocompatibility complex (SLA) molecules. Examples of porcine particularities such as the double-positive T lymphocytes with the phenotype CD(4+)CD8(low) and CD(4-)CD8(low) alphabeta T cell subsets and the persistence of SLA class II after T-lymphocyte activation are illustrated, as well as the shared characteristics of the Artiodactyla group, such as the high proportion of gammadelta TcR (T cell receptor) T cells in blood and other lymphoid tissues. Furthermore, discrepancies between swine and humans, such as CD16 expression on dendritic cells and CD11b (wCD11R1) tissue distribution are outlined. The rapidly growing information should facilitate manipulation of the swine immune system towards improving disease control, and open new avenues for biomedical research using the pig as a model.

In vivo oral administration effects of various oligodeoxynucleotides containing synthetic immunostimulatory motifs in the immune response to pseudorabies attenuated virus vaccine in newborn piglets

Numerous studies have demonstrated that oligonucleotides containing CpG motifs (CpG ODN) are efficient immunoadjuvants to various antigens administered by parenteral routes to mice. Recently, it has been found that CpG ODNs also is a promising mucosal adjuvant in mice. To date, there have been no studies to screen the optimal CpG sequence and modified ODN backbone to piglets in vivo, when delivered by oral route. We have previously demonstrated that human-specific CpG ODN is a potent adjuvant to pseudorabies live attenuated virus (PRV) vaccine when administered subcutaneously (SC) or ocularly in piglets. In this study, we screened and evaluated the optimal CpG sequences (porcine-specific, human-specific, mouse-specific ODN) and optimal backbone (SOS-backbone consisting of a nuclease-resistant phosphorothioate guanosines at the 5' and the 3'-end and with a phosphodiester (O) in the center and phosphorothioate (S) backbone (S-backbone)) to PRV vaccine delivered orally in piglets. The proliferation of peripheral blood mononuclear cells (PBMCs), IFN-gamma and IL-4 in serum, and the titre of IgG, IgG2/IgG1 isotype in serum and IgA in intestinal washings and feces to PRV vaccine were tested at different time-points. The results suggested that, CpG ODNs augmented systemic (IgG in serum, T-cell proliferation) and mucosal (IgA in intestinal washings and feces) immune responses against antigen. CpG ODNs stimulated both T-helper type1 (Th1) (IgG2) and Th2 (IgA) responses when delivered orally. With the same backbone, the porcine-specific ODN-induced responses were comparable with human-specific ODNs, but stronger than mouse-specific CpG ODNs. SOS-backbone induced a stronger IFN-gamma and proliferative responses than S-backbone, while antibody responses induced by SOS-backbones were slightly less or similar with S-backbone. The in vivo data demonstrate for the first time that porcine-specific and human-specific ODNs both are optimal sequences for mucosal system in piglets.

Intranasal administration of CpG oligonucleotides induces mucosal and systemic Type 1 immune responses and adjuvant activity to porcine reproductive and respiratory syndrome killed virus vaccine in piglets in vivo

Oligonucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice. Recently, it has been showed that CpG ODN is a promising mucosal adjuvant in mice, but data on mucosal immune responses induced by CpG ODN in piglets are scarce. We have previously demonstrated that CpG ODN is a potent adjuvant to pseudorabies attenuated virus (PRV) vaccine when administered subcutaneously (SC) in newborn piglets. Herein, we evaluated intranasal (IN) delivery of CpG ODN with porcine reproductive and respiratory syndrome (PRRS) killed virus vaccine (PRRSV) to determine its potential as a mucosal adjuvant to a commercial vaccine. CpG ODN augmented systemic (IgG in serum, Peripheral blood mononuclear cells (PBMC) proliferation) and mucosal (IgA in feces, nasal and oral secretions) immune responses against antigen. CpG ODN stimulated both T-helper type1 (Type 1) (IgG2) and Type 2 (IgA) responses when delivered intranasally. Results from this study indicate that stimulatory CpG ODN may be effective as a mucosal adjuvant with commercial vaccine in husbandry animals.

CpG oligodeoxynucleotides augment the immune responses of piglets to swine Pasteurella multocida living vaccine in vivo

Oligodeoxynucleotides containing unmethylated CpG motifs (CpG ODN) prevent development of T-helper type 2 (Th2) immune response and reverse established allergic responses in mouse models. However, little work on immune responses in piglets has been conducted in vivo. In this report, the ability of a porcine-specific CpG ODN to act as an immunostimulant and enhance immune responses of piglets to swine Pasteurella multocida living vaccine (SPML vaccine) was determined. The titre of IgG and IgG1/IgG2 isotype to SPML vaccine in serum, the proliferation of lymphocytes, SPML-specific interferon-gamma (IFN-gamma) and IL-6, TNF-alpha, IL-4 production of PBMCs in vitro and IFN-gamma, IL-6, TNF-alpha, IL-4, IL-10 in piglets serum were examined to identify the immune responses of the piglets. Immune responses of the piglets vaccinated with SPML and CpG ODN were significantly stronger than responses of piglets vaccinated with SPML alone. All these data summarized that immunostimulatory CpG ODN could modulate the immune response towards a Th1-like response when co-administered to piglets during SPML vaccination, which suggested that the therapeutic uses envisioned for these ODNs (as vaccine adjuvants and immunoprotective agents) may be applicable to husbandry animals.

Vaccination with porcine reproductive and respiratory syndrome killed virus vaccine and immunostimulatory oligodeoxynucleotides induces specific immunity in piglets

A large number of studies demonstrated the immunostimulatory effects of CpG oligonucleotides (ODN), particularly in mice. In present study, the objective was to investigate the immunoadjuvant effects of CpG ODN to porcine reproductive and respiratory syndrome (PRRS) killed virus vaccine (PRRSV) and its protective effects against PRRS virus in piglets. The PRRSV-specific antibodies titres and serum IgG1/IgG2 titres, the proliferation of lymphocytes, PRRSV-specific IFN-gamma, the expression of major histocompatibility complex class II (MHCII) of peripheral blood mononuclear cells (PBMCs) and post-challenge clinical protection were examined to identify the immune responses of the piglets. The results were found that the above-mentioned immune responses of the piglets inoculated with CpG ODN plus PRRSV were significantly stronger than those indued by PRRSV or PBS control groups. All these data suggested that CpG ODN could be employed as effective immunoadjuvant to raise the humoral and cellular responses of the piglets to PRRSV.

In vivo effects of oligodeoxynucleotides containing synthetic immunostimulatory motifs in the immune response to swine streptococcic septicemia vaccine in weaned piglets

The diverse immunostimulatory effects of CpG oligodeoxynucleotides (CpG ODN) have been demonstrated extensively in mice and human. Although the immunoadjuvant effects of CpG ODN in pigs were also studied in several reports, until now, little work has been carried out with regard to their effects on the adaptive immune system of newly weaned piglets. In this study, swine streptococcic septicemia killed vaccine (SSSK vaccine) was used as antigen, we assessed the in vivo immunostimulatory effects of different CpG motifs in newly weaned piglets. The proportion of CD4(+), CD8(+) T lymphocytes subpopulations and proliferation of peripheral blood mononuclear cells (PBMCs), IFN-gamma and IL-6 in serum, and the titre of IgG and IgG2/IgG1 isotype to SSSK vaccine in serum were tested at different time-points. The results suggested that, the CD4(+)/CD8(+) ratio decreased significantly in weaned piglets inoculated with phosphate buffer saline (PBS) alone, however, it was stable in CpG ODN-coinoculated newly weaned piglets. IFN-gamma and IL-6 levels, the titres of specific antibodies IgG, IgG2 and proliferative responses of CpG ODN-coinjected piglets were all significantly higher than those of SSSK vaccine alone or PBS or GpC ODN-coinjected piglets. The porcine-specific ODN-induced responses were stronger in animals injected with human-specific or mouse-specific CpG ODN. These in vivo data demonstrate for the first time that CpG ODN can stimulate adaptive immune system in weaned piglets.

In vivo effects of oligodeoxynucleotides containing synthetic immunostimulatory motifs in weaned piglets

The innate immunostimulatory effects of CpG ODN have been demonstrated in mouse, monkey, sheep and chicken in some reports. Unfortunately, little work has been carried out with regard to their effects on the innate immune system of weaned piglets. In this study, the proportion of CD4(+), CD8(+) T lymphocytes subpopulations and interferon-gamma (IFN-gamma) and IL-4 in serum, proliferation of peripheral blood mononuclear cells (PBMCs) were tested at different time-points. The results suggested that, the CD4(+)/CD8(+) ratio decreased significantly in weaned piglets inoculated with phosphate buffer saline (PBS) alone, however, it was stable in CpG ODN-inoculated piglets. Proliferation of PBMCs and IFN-gamma levels of CpG ODN-injected piglets were significantly higher than those of PBS-injected piglets. The ODN-induced responses were stronger in animals injected with CpG ODN formulated in 30% emulsigen than in PBS and alum. The innate immunostimulatory activity of CpG ODN appeared to be in dose-dependent manner. These in vivo data demonstrate for the first time that CpG ODN can stimulate innate immune system in weaned piglets.

CpG oligodeoxynucleotides as DNA adjuvants in vertebrates and their applications in immunotherapy

The genomes of bacterial and viral DNA contain a much higher frequency of unmethylated CpG dinucleotides than those of vertebrates. This difference in genome structure allows the innate immune system of vertebrates to distinguish bacterial or viral DNA from self-DNA, and consequently to perceive a 'danger signal' when bacterial or viral DNA is encountered. Multiple sources of evidence suggest that CpG motifs, including bacterial DNA and CpG ODNs (synthetic oligodeoxynucleotides containing unmethylated CpG), are capable of evoking a range of immunostimulatory effects in vertebrates and have a tremendous potential to be used as therapeutic agents and adjuvants. CpG motifs with different sequences have been shown to induce various types or levels of immunostimulatory responses whereas the immunostimulatory effects of CpG motifs are species-specific. A better understanding of CpG recognition at the molecular level is fundamental to the identification of those motifs that have desired immunostimulatory responses. It is hoped that this would allow the optimization and application of CpG motifs as therapeutic agents and adjuvants, for numerous diseases in various species.

The efficacy of CpG oligodinucleotides, in combination with conventional adjuvants, as immunological adjuvants to swine streptococcic septicemia vaccine in piglets in vivo

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, the immunostimulatory effects of CpG in combination with aluminum hydroxide (alum) or Emulsigen (Em) were investigated in cattle, rabbits or mice, but not piglets. In this report, using the swine streptococcus as model bacteria, the efficacy of CpG ODN as an adjuvant for piglets was assessed alone and in combination with alum (CpG/alum) or Em (CpG/Em). The CpG/alum or CpG/Em combination elicited greater immune responses to swine streptococcic septicemia killed vaccine (SSSK vaccine) compared with CpG alone, or alum or Em. A GpC/alum or GpC/Em combination did not have the same effects as CpG/alum or CpG/Em suggesting that the adjuvanticity was related to the CpG motifs. In addition, we also found that the 10% Em in combination with CpG ODN had similar immunological effects as 30% Em combination. Our results demonstrate that the addition of CpG ODN to alum or to Em significantly improves the efficiency of the adjuvants in piglets.

Adjuvants modulating mucosal immune responses or directing systemic responses towards the mucosa

In developing veterinary mucosal vaccines and vaccination strategies, mucosal adjuvants are one of the key players for inducing protective immune responses. Most of the mucosal adjuvants seem to exert their effect via binding to a receptor/or target cells and these properties were used to classify the mucosal adjuvants reviewed in the present paper: (1) ganglioside receptor-binding toxins (cholera toxin, LT enterotoxin, their B subunits and mutants); (2) surface immunoglobulin binding complex CTA1-DD; (3) TLR4 binding lipopolysaccharide; (4) TLR2-binding muramyl dipeptide; (5) Mannose receptor-binding mannan; (6) Dectin-1-binding ss 1,3/1,6 glucans; (7) TLR9-binding CpG-oligodeoxynucleotides; (8) Cytokines and chemokines; (9) Antigen-presenting cell targeting ISCOMATRIX and ISCOM. In addition, attention is given to two adjuvants able to prime the mucosal immune system following a systemic immunization, namely 1alpha, 25(OH)2D3 and cholera toxin.

Co-administration of porcine-specific CpG oligodeoxynucleotide enhances the immune responses to pseudorabies attenuated virus vaccine in newborn piglets in vivo

Oligonucleotides containing CpG motifs (CpG ODN) are strong adjuvants for humoral and cellular immune responses in mice, but data on immune responses in piglets are scarce. In this report, porcine-specific CpG ODN were used as immunoadjuvants to enhance the immune responses of the newborn piglets to Pseudorabies attenuated virus (PRV) vaccine. The titres of specific antibodies and serum IgG1/IgG2 ratio to PRV vaccine, the proliferation of peripheral blood mononuclear cells (PBMCs), IL-4 and interferon-gamma(IFN-gamma) in piglets serum were examined to identify the immune response of the newborn piglets. The results showed that piglets immunized with PRV vaccine and CpG ODN presented high titers of PRV-specific antibodies and IgG2 isotype, a Th1-dominated (IFN-gamma) cytokine profile, together with inducing higher proliferation of PBMCs. All these data indicate that CpG ODN are potential effective adjuvants for the PRV vaccine in newborn piglets.

Effects of CpG ODN on CD4+ and CD8+ T subpopulations in the immune response to porcine reproductive and respiratory syndrome killed virus vaccine

CpG ODN is a noval immunostimulatory reagent In this research, the effects of immunostimulatory CpG oligodeoxynucleotides (CpG ODN) on CD4+ and CD8+ T lymphocytes subpopulations in the newborn piglets blood were tested at different time with porcine reproductive and respiratory syndrome killed virus vaccine (PRRS vaccine) with or without CpG ODN. The results suggested that, the CD4+/CD8+ ratio decreased with age in piglets inoculated with vaccine alone or GpC ODN with vaccine or phosphate buffer saline (PBS), however, it was stable in piglets co-inoculated with CpG ODN and PRRS vaccine (p>0.05), the use of CpG ODN can prevent effectively the reduction of the proportion of CD4+ T lymphocytes. High titers of PRRS specific antibody can also be tested in the newborn piglets serum immunized PRRS vaccine and CpG ODN (p<0.05).

CpG oligodinucleotides induce strong humoral and cellular responses to swine streptococcic septicemia vaccine in piglets in vivo

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, but data on humoral and cellular immune responses in piglets are scarce. In this report, using the swine streptococcus as model bacteria, CpG ODN was used as immunoadjuvants to enhance the immune responses of the piglets to swine streptococcic septicemia killed vaccine (SSSK vaccine). The titre of specific antibodies to SSSK vaccine, the proliferation of lymphocytes, SSSK-specific interferon-gamma(IFN-gamma) and IL-6, the expression of major histocompatibility complex class II (MHC-II) and CD14 of peripheral blood mononuclear cells (PBMCs) were examined to identify the immune responses of the piglets. The results were found that the above-mentioned immune responses of the piglets with CpG ODN were significantly stronger than standard immunization protocols. All these data suggested that immunostimulatory CpG ODN was promising immune enhancers for vaccination against SSSK vaccine.