Use of CpG oligodeoxynucleotides as immunoprotective agents

Sani J, Raz A, Zakeri S, Dinparast Djadid N, Abouie Mehrizi A. Malaria transmission blocking activity of Anopheles stephensi alanyl aminopeptidase N antigen formulated with MPL, CpG, and QS21 adjuvants

BACKGROUNDS

Malaria, a preventive and treatable disease, is still responsible for annual deaths reported in most tropical regions, principally in sub-Saharan Africa. Subunit recombinant transmission-blocking vaccines (TBVs) have been proposed as promising vaccines to succeed in malaria elimination and eradication. Here, a provisional study was designed to assess the immunogenicity and functional activity of alanyl aminopeptidase N (APN1) of Anopheles stephensi, as a TBV candidate, administered with MPL, CpG, and QS21 adjuvants in the murine model.

METHODOLOGY/PRINCIPAL FINDINGS

The mouse groups were immunized with recombinant APN1 (rAPN1) alone or formulated with CpG, MPL, QS-21, or a combination of adjuvants (CMQ), and the elicited immune responses were evaluated after the third immunization. The standard membrane feeding assay (SMFA) measured the functional activity of antibodies against bacterial-expressed APN1 protein in adjuvanted vaccine groups on transmission of P. falciparum (NF54) to An. stephensi mosquitoes. Evaluation of mice vaccinated with rAPN1 formulated with distinct adjuvants manifested a significant increase in the high-avidity level of anti-APN1 IgG and IgG subclasses; however, rAPN1 induced the highest level of high-avidity anti-APN1 IgG1, IgG2a, and IgG2b antibodies in the immunized vaccine group 5 (APN1/CMQ). In addition, vaccine group 5 (receiving APN1/CMQ), had still the highest level of anti-APN1 IgG antibodies relative to other immunized groups after six months, on day 180. The SMFA data indicates a trend towards higher transmission-reducing activity in groups 2 and 5, which received the antigen formulated with CpG or a combination of three adjuvants.

CONCLUSIONS/SIGNIFICANCE

The results have shown the capability of admixture to stimulate high-affinity and long-lasting antibodies against the target antigen to hinder Plasmodium parasite development in the mid-gut of An. stephensi. The attained results authenticated APN1/CMQ and APN1/CpG as a potent APN1-based TBV formulation which will be helpful in designing a vaccine in the future.

Morphology Dictated Immune Activation with Framework Nucleic Acids

Framework nucleic acids (FNAs) of various morphologies, designed using the precise and programmable Watson-Crick base pairing, serve as carriers for biomolecule delivery in biology and biomedicine. However, the impact of their shape, size, concentration, and the spatial presentation of cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) on immune activation remains incompletely understood. In this study, representative FNAs with varying morphologies are synthesized to explore their immunological responses. Low concentrations (50 nM) of all FNAs elicited no immunostimulation, while high concentrations of elongated DNA nanostrings and tetrahedrons triggered strong activation due to their larger size and increased cellular uptake, indicating that the innate immune responses of FNAs depend on both dose and morphology. Notably, CpG ODNs' immune response can be programmed by FNAs through regulating the spatial distance, with optimal spacing of 7-8 nm eliciting the highest immunostimulation. These findings demonstrate FNAs' potential as a designable tool to study nucleic acid morphology's impact on biological responses and provide a strategy for future CpG-mediated immune activation carrier design.

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.

GRA8 DNA vaccine formulations protect against chronic toxoplasmosis

Toxoplasma gondii has a very wide host range and infects all warm-blooded animals including humans. The disease causes great economic losses both in animals and humans. Vaccination is the most effective approach to fight against toxoplasmosis however an effective vaccine has not been developed yet. In the present study, GRA8 protein of T. gondii that showed high immunogenicity in our previous microarray screening study was used to develop a DNA vaccine using pcDNA 3.3 vector for the first time. In order to increase the potency of the DNA vaccine, 10 times lower amount of GRA8 DNA vaccine was combined with molecular adjuvant CpG and formulated into a commercial liposome (pcDNA3.3-GRA8+CpG+Escort). Mice were vaccinated intramuscularly two times at three-week intervals and challenged orally with the T. gondii PRU strain tissue cysts. The humoral immune response was determined by Western Blot and ELISA. The cellular immune response was analyzed by flow cytometry, cytokine ELISA and MTT assay. Among the vaccine groups, pcDNA3.3-GRA8 and pcDNA3.3-GRA8+CpG+Escort induced strong IgG response compared to controls (P < 0.001). The IgG1 and IgG2a responses showed a balanced Th1-Th2 polarization. The ratio of CD4⁺ and CD8⁺ T lymphocytes secreting IFN-γ increased, and significantly higher extracellular IFN-γ secretion was achieved compared to the controls (P < 0.01). The amount of tissue cysts in the group of mice vaccinated with pcDNA3.3-GRA8 decreased significantly compared to control groups (P < 0.0001). In the group vaccinated with pcDNA3.3-GRA8+CpG+Escort, the amount of tissue cysts also decreased significantly compared to PBS (P = 0.0086) and Empty plasmid+CpG+Escort (P = 0.0007) groups. This study showed for the first time that pcDNA 3.3. vector encoding GRA8 with or without CpG and Liposome can induce strong cellular and humoral immune responses and confer strong protection against mouse model of chronic toxoplasmosis.

Use of Protamine in Nanopharmaceuticals-A Review

Macromolecular biomolecules are currently dethroning classical small molecule therapeutics because of their improved targeting and delivery properties. Protamine-a small polycationic peptide-represents a promising candidate. In nature, it binds and protects DNA against degradation during spermatogenesis due to electrostatic interactions between the negatively charged DNA-phosphate backbone and the positively charged protamine. Researchers are mimicking this technique to develop innovative nanopharmaceutical drug delivery systems, incorporating protamine as a carrier for biologically active components such as DNA or RNA. The first part of this review highlights ongoing investigations in the field of protamine-associated nanotechnology, discussing the self-assembling manufacturing process and nanoparticle engineering. Immune-modulating properties of protamine are those that lead to the second key part, which is protamine in novel vaccine technologies. Protamine-based RNA delivery systems in vaccines (some belong to the new class of mRNA-vaccines) against infectious disease and their use in cancer treatment are reviewed, and we provide an update on the current state of latest developments with protamine as pharmaceutical excipient for vaccines.

Als3-Th-cell-epitopes plus the novel combined adjuvants of CpG, MDP, and FIA synergistically enhanced the immune response of recombinant TRAP derived from Staphylococcus aureus in mice

INTRODUCTION

Staphylococcus aureus (S. aureus) is a gram-positive opportunistic pathogen, there are currently no high effective vaccine against S. aureus in humans and animals, the development of an efficient vaccine remains an important challenge to prevent S. aureus infection. Here, we prepared Als3-Th-cell-epitope-Target of RNAIII Activating Protein (TRAP) (ATT) proteins plus the novel combined adjuvants to develop a promising vaccine candidate against S. aureus.

METHODS

The recombinant pET-28a (+)-att plasmids were constructed, and the ATT proteins were expressed and obtained, then, ATT plus Freund's adjuvant or the novel combined adjuvants of cytosine-phosphate-guanosine oligodeoxynucleotides (CpG), muramyl dipeptides (MDP), and FIA were immunized in mice. After booster immunization, the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), IL-10 and IL-17A cytokine were evaluated, the humoral immune responses against TRAP were detected in mice, and the survival rate of mice was confirmed by challenge assay.

RESULTS

The mice immunized with ATT plus Freund's adjuvant exhibited significantly higher level of IFN-γ, IL-4, IL-10, and IL-17A, and displayed the stronger humoral immune response against TRAP than control groups, importantly, the survival rate of these mice was significantly higher than control groups. In addition, compared with the control groups, ATT + CpG + MDP + FIA group was elicited significantly higher level of IFN-γ, IL-4, IL-10, and IL-17A and was triggered the stronger humoral immune responses against TRAP, moreover, generated the higher survival rate of mice.

CONCLUSION

Als3 epitopes significantly enhanced TRAP immunogenicity. ATT plus the novel combined adjuvants of CpG, MDP, and FIA induced the strong immune response and protection against S. aureus, revealing the combination of CpG, MDP, and FIA adjuvant acts the synergistic effect.

Synthetic Hexanucleotides as a Tool to Overcome Excessive Neutrophil Activation Caused by CpG-Containing Oligonucleotides

Mimicking bacterial DNA, synthetic CpG-containing oligodeoxyribonucleotides (CpG-ODNs) have a powerful immunomodulatory potential. Their practical application is mainly associated with the production of vaccines, where they are used as adjuvants, as well as in local antimicrobial therapy. CpG-ODNs act on a wide variety of immune cells, including neutrophilic granulocytes. On the one hand, the stimulatory effect provides both the direct implementation of their antimicrobial and fungicidal mechanisms, and an avalanche-like strengthening of the immune signal due to interaction with other participants in the immune process. On the other hand, hyperactivation of neutrophilic granulocytes can have negative consequences. In particular, the formation of unreasonably high amounts of reactive oxygen species leads to tissue damages and, as a consequence, a spontaneous aggravation and prolongation of the inflammatory process. Under physiological conditions, a large number of DNA fragments are present in inflammation foci: both of microbial and self-tissue origin. We investigated effects of several short modified hexanucleotides on the main indicators of neutrophil activation, as well as their influence on the immunomodulatory activity of known synthetic CpG-ODNs. The results obtained show that short oligonucleotides partially inhibit the prooxidant effect of synthetic CpG-ODNs without significantly affecting the ability of the latter to overcome bacteria-induced pro-survival effects on neutrophilic granulocytes.

The novel combinations of CTB, CpG, and aluminum hydroxide significantly enhanced the immunogenicity of clumping factor A 221-550 of Staphylococcus aureus

Here, we prepared the novel combined adjuvants, CTB as intra-molecular adjuvant, CpG and aluminum hydroxide (Alum) to strengthen the immunogenicity of clumping factor A_221-550 of Staphylococcus aureus (S. aureus). The protein-immunoactive results showed CTB-ClfA_221-550 elicited the strong immune responses to serum from mice immunized with CTB and ClfA_221-550, respectively. The mice immunized with CTB-ClfA_221-550 plus CpG and Alum adjuvant exhibited significantly stronger CD4⁺ T cell responses for IFN-γ, IL-2, IL-4, and IL-17 and displayed the higher proliferation response of splenic lymphocytes than the control groups, in addition, these mice generated the strongest humoral immune response against ClfA_221-550 among all groups. Our results also showed CTB-ClfA_221-550 plus CpG and Alum adjuvant obviously increased the survival percentage of the mice challenged by S. aureus. These data suggested that the novel combined adjuvants, CTB, CpG, and Alum, significantly enhance the immune responses triggered with ClfA_221-550, and could provide a new approach against infection of S. aureus.

ABBREVIATIONS

CTB: Cholera Toxin B; CpG: Cytosine preceding Guanosine; ODN: Oligodeoxynucleotides; Alum: Aluminum hydroxide; TRAP: Target of RNAIII-activating Protein; TLR9: Toll-like Receptor 9; TMB: 3, 3', 5, 5'-tetramethylbenzidine; mAbs: Monoclonal Antibodies; OD: Optical Densities; S. aureus: Staphylococcus aureus; ClfA: Clumping factor A; FnBPA: Fibronection-binding protein A; IsdB: Iron-regulated surface determinant B; SasA: Staphylococcus aureus Surface Protein A; GapC: Glycer-aldehyde-3-phosphate dehydrogenase-C.

Single Stranded DNA Immune Modulators with Unmethylated CpG Motifs: Structure and Molecular Recognition by Toll-Like Receptor 9

Single stranded microbial DNA fragments with unmethylated deoxycytidylyldeoxyguanosine dinucleotide (CpG) motifs are interpreted as danger signals by the innate immune system via recognition by the Toll-like Receptor 9 (TLR9). Their synthetic analogues, Oligodeoxynucleotides (ODN) comprise a promising class of immune modulators with potential applications in the treatment of multiple diseases, such as cancer, autoimmune diseases or allergy. ODN molecules contain a core hexamer sequence, which is species specific consisting of GACGTT and AACGT for mouse and GTCGTT in humans. Assessment of structural features of different type of ODNs is highly challenging. NMR spectroscopic insights were gained for a short, single CpG motif containing ODN 1668. The structural basis of ODN recognition by TLR9 recently started to unravel as crystal structures of TLR9 orthologues in complex with ODN 1668 were solved. Systematic investigations of ODN sequences revealed that ODNs with a single CpG motif are capable of activating mouse TLR9, but two closely positioned CpG motifs are necessary for activation of human TLR9. Furthermore, longer ODNs with TCC and TCG sequences at the 5' end were shown to activate TLR9 with higher efficiency. It was revealed that 5'-xCx motif containing short ODNs (sODN) are able to augment the immune response of short, single CpG containing ODNs, which are incapable of activating of TLR9 alone. All these observations pointed to the existence of a second binding site on TLR9, which was characterized in crystal structures that delivered further insights of the nucleic acid recognition of the innate immune system by TLR9.

CpG ODN D35 improves the response to abbreviated low-dose pentavalent antimonial treatment in non-human primate model of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) affects the lives of 0.7–1 million people every year causing lesions that take months to heal. These lesions can result in disfiguring scars with psychological, social and economic consequences. Antimonials are the first line of therapy for CL, however the treatment is lengthy and linked to significant toxicities; further, its efficacy is variable and resistant parasites are emerging. Shorter or lower dose antimonial treatment regimens, which would decrease the risk of adverse events and improve patient compliance, have shown reduced efficacy and further increase the risk emergence of antimonial-resistant strains. The progression of lesions in CL is partly determined by the immune response it elicits, and previous studies showed that administration of immunomodulatory type D CpG ODNs, magnifies the immune response to Leishmania and reduces lesion severity in nonhuman primates (NHP) challenged with Leishmania major or Leishmania amazonensis. Here we explored whether the addition of a single dose of immunomodulating CpG ODN D35 augments the efficacy of a short-course, low-dose pentavalent antimonial treatment regimen. Results show that macaques treated with D35 plus 5mg/kg sodium stibogluconate (Sb^V) for 10 days had smaller lesions and reduced time to re-epithelization after infection with Leishmania major. No toxicities were evident during the studies, even at doses of D35 10 times higher than those used in treatment. Critically, pentavalent antimonial treatment did not modify the ability of D35 to induce type I IFNs. The findings support the efficacy of D35 as adjuvant therapy for shorter, low dose pentavalent antimonial treatment.

Cutaneous leishmaniasis is a devastating disease that affects close to a million people every year. Its clinical presentation ranges from small uncomplicated lesions that heal over a few months to debilitating large chronic or recurring lesions that result in disfigurement, stigma, and economic loss. Antimonials are the first line treatment for cutaneous leishmaniasis in most countries, but the lengthy treatment schedules, significant associated toxicities, and the emergence of resistant strains, require the development of alternative strategies. As the immune response is a key determinant of disease course, immunomodulatory therapies could be harnessed to act in concert with antimonials to improve the safety and efficacy of CL treatment. Synthetic oligonucleotide D35 selectively activates plasmacytoid dendritic cells and was previously shown to reduce the severity of L. major and L. amazonensis lesions in rhesus macaques, but its activity in combination with antimonials was unknown. Our studies show that a single subcutaneous dose of innate immune modulator D35 improved the response to a low-dose abbreviated antimonial course, reducing the severity of the lesions and accelerating healing in primates. No toxicities were evident with D35 at doses ten-fold higher than the effective dose. The studies suggest that the combined therapy strategy shows clinical promise.

CpG Oligonucleotides Protect Mice From Alphavirus Encephalitis: Role of NK Cells, Interferons, and TNF

Arboviruses including alphavirus are responsible for most emerging infectious diseases worldwide. Recent outbreaks of chikungunya virus serve as a stark reminder to their pathogenic potential. There are no vaccines or therapeutics currently available to contain alphavirus outbreaks. In this study we evaluated the effect of immunomodulatory CpG ODN on the clinical progression of neurotropic Sindbis virus infection. Neonatal C57Bl-6 mice challenged with Sindbis virus AR339 (25 PFU Subcutaneous) infect neurons in the CNS leading to the development of ataxia, seizures, paralysis, and death. We show that systemic administration of CpG ODN modulates the cytokine and chemokine gene expression levels in the CNS and ultimately protects neonatal mice from lethal neurotropic infection. The protection conferred by CpG ODN is controlled by innate immune response and T and B cells were dispensable. Further, protection required Type I, Type II interferons, and TNF as well as functional NK cells, but did not involve iNOS. This study confirms that administration of innate immune modulators can be used as a strategy to boost host innate immune responses and protect against neurotropic viruses reducing their pathogenic footprint.

Potent anti-tumor immunostimulatory biocompatible nanohydrogel made from DNA

Unmethylated CpG oligodeoxynucleotides are potent immunostimulatory motifs in activating both innate and acquired immune system by inducing Th1 type antigen-specific T cell responses, but their instability in serum greatly influences their immunostimulant efficiency. Here, we constructed a novel immuno-DNA nanohydrogels consisting of tandem repeat sequences of CpG units named CpG-MCA nanohydrogels through multi-primed chain amplification. CpG-MCA nanohydrogels were proved to resist degradation and increase the proliferation and migration of murine macrophage-like RAW264.7 cells. Furthermore, CpG-MCA nanohydrogels effectively induced high expression of tumor necrosis factor-α and interleukin-6, and remarkably inhibited the proliferation of U251 cells, suggesting that CpG-MCA nanohydrogels are expected to be employed as the potent anti-cancer immunostimulant.

Combining Monophosphoryl Lipid A (MPL), CpG Oligodeoxynucleotide (ODN), and QS-21 Adjuvants Induces Strong and Persistent Functional Antibodies and T Cell Responses against Cell-Traversal Protein for Ookinetes and Sporozoites (CelTOS) of Plasmodium falciparum in BALB/c Mice

Plasmodium falciparum cell-traversal protein for ookinetes and sporozoites (PfCelTOS) is an advanced vaccine candidate that has a crucial role in the traversal of the malaria parasite in both mosquito and mammalian hosts. As recombinant purified proteins are normally poor immunogens, they require to be admixed with an adjuvant(s); therefore, the objective of the present study was to evaluate the capacity of different vaccine adjuvants, monophosphoryl lipid A (MPL), CpG, and Quillaja saponaria Molina fraction 21 (QS-21), alone or in combination (MCQ [MPL/CpG/QS-21]), to enhance the immunogenicity of Escherichia coli-expressed PfCelTOS in BALB/c mice. This goal was achieved by the assessment of anti-PfCelTOS IgG antibodies (level, titer, IgG isotype profile, avidity, and persistence) and extracellular Th1 cytokines using an enzyme-linked immunosorbent assay (ELISA) on postimmunized BALB/c mouse sera and PfCelTOS-stimulated splenocytes, respectively. Also, an assessment of the transmission-reducing activity (TRA) of anti-PfCelTOS obtained from different vaccine groups was carried out in female Anopheles stephensi mosquitoes by using a standard membrane feeding assay (SMFA). In comparison to PfCelTOS alone, administration of PfCelTOS with three distinct potent Th1 adjuvants in vaccine mouse groups showed enhancement and improvement of PfCelTOS immunogenicity that generated more bias toward a Th1 response with significantly enhanced titers and avidity of the anti-PfCelTOS responses that could impair ookinete development in A. stephensi However, immunization of mice with PfCelTOS with MCQ mixture adjuvants resulted in the highest levels of induction of antibody titers, avidity, and inhibitory antibodies in oocyst development (88%/26.7% reductions in intensity/prevalence) in A. stephensi It could be suggested that adjuvant combinations with different mechanisms stimulate better functional antibody responses than adjuvants individually against challenging diseases such as malaria.

The double adjuvants LTB and CpG significantly enhanced the immuno-protective effects of recombinant GIT derived from Staphylococcus aureus and Streptococcus in mice

PURPOSE

In this study, we prepared GapC1-150-IsdB126-361-TRAP (GIT) proteins plus heat-labile enterotoxin B (LTB) as an intra-molecular adjuvant, together with CpG to further enhance its immunogenicity.

METHODOLOGY

Initially, the target genes were acquired and inserted into pET-32a (+) vectors to express LTB-GIT protein. LTB-GIT expression was confirmed by Western blotting and its immunocompetence was estimated through ELISA. Further, we immunized BALB/c mice with the LTB-GIT plus CpG adjuvant. After the second immunization, the antigen-specific CD4⁺ cell responses for IFN-γ, IL-2, IL-4 and IL-10 were monitored by intracellular cytokine staining (ICS) assay. After the third immunization, the level of IgG antibodies in the serum from immunized groups was assessed by ELISA, and the protective immune response was appraised by Staphylococcus aureus and Streptococcus dysgalactiae challenge.

RESULTS

The ELISA results showed that the OD450nm value of the LTB-GIT group was significantly higher than that of the BSA group. The group immunized with LTB-GIT plus CpG exhibited significantly stronger CD4⁺ T cell responses for IFN-γ, IL-2, IL-4 and IL-10 compared to the group immunized with LTB-GIT, GIT alone orLTB-GIT plus CpG. In addition, the group immunized with LTB-GIT plus CpG generated the highest level of IgG antibodies against GIT among all of the groups, and our results also showed that LTB-GIT plus CpG markedly improved the survival percentage of mice compared to other groups.

CONCLUSION

We confirmed that the novel double adjuvants, LTB and CpG, are able to significantly improve GIT-induced immune responses. This formula could be a promising strategy for enhancing the immune efficacy of multi-subunit vaccines against Staphylococcus aureus and streptococcal infection.

Mechanisms of TLR9 activation

Non-methylated CpG-motifs in bacterial or viral DNA are recognized by TLR9 as foreign. The activation of TLR9 by microbial DNA or synthetic oligonucleotides based on these motifs leads to the induction of innate immune responses. We have compared the subcellular localization of fluorescent versions of TLR9 and TLR4 and found that TLR9 is expressed in the endoplasmic reticulum while TLR4 is expressed on the plasma membrane. Fluorescently tagged bacterial DNA or CpG-DNA was observed to traffic to a tubular lysosomal compartment in human pDCs. In stimulated cells, TLR9 translocated to CpG-DNA or microbial DNA containing structures in the endosome, where TLR9 binds to DNA and initiates signaling.

Adjuvants: Classification, Modus Operandi, and Licensing

Vaccination is one of the most efficient strategies for the prevention of infectious diseases. Although safer, subunit vaccines are poorly immunogenic and for this reason the use of adjuvants is strongly recommended. Since their discovery in the beginning of the 20th century, adjuvants have been used to improve immune responses that ultimately lead to protection against disease. The choice of the adjuvant is of utmost importance as it can stimulate protective immunity. Their mechanisms of action have now been revealed. Our increasing understanding of the immune system, and of correlates of protection, is helping in the development of new vaccine formulations for global infections. Nevertheless, few adjuvants are licensed for human vaccines and several formulations are now being evaluated in clinical trials. In this review, we briefly describe the most well known adjuvants used in experimental and clinical settings based on their main mechanisms of action and also highlight the requirements for licensing new vaccine formulations.

Nanodelivery systems for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

Synthetic oligodeoxynucleotides containing immunostimulatory CpG motif mimic bacterial DNA and are potent activator of innate and adaptive immune responses. Therefore, CpG ODNs have significant potentials as immunotherapeutic agent for treatment of infectious diseases, allergy and cancer. Many clinical trials involving CpG ODNs either used alone or as adjuvant have been initiated. However, delivery of CpG ODNs to target sites still remains a great challenge due to their extreme susceptibility to nuclease degradation in serum and poor cellular uptake. Chemical modification of CpG ODNs backbone can protect them against degradation by nucleases, but have raised concern regarding several severe side effects. Development of efficient CpG ODNs delivery systems to address these issues and enhance their immunostimulatory effect are highly desirable. In recent years, the emergence of nanotechnology has provided unprecedented opportunities to encapsulate CpG ODN into various nanocarriers or synthesize CpG ODNs nanostructures. This review provides an overview of the delivery systems based on nanomaterials and nanostructures newly developed for enhancing the immunostimulatory effect of CpG ODNs, together with a brief discussion on perspectives for future studies in this field.

Liposome-Based Adjuvants for Subunit Vaccines: Formulation Strategies for Subunit Antigens and Immunostimulators

The development of subunit vaccines has become very attractive in recent years due to their superior safety profiles as compared to traditional vaccines based on live attenuated or whole inactivated pathogens, and there is an unmet medical need for improved vaccines and vaccines against pathogens for which no effective vaccines exist. The subunit vaccine technology exploits pathogen subunits as antigens, e.g., recombinant proteins or synthetic peptides, allowing for highly specific immune responses against the pathogens. However, such antigens are usually not sufficiently immunogenic to induce protective immunity, and they are often combined with adjuvants to ensure robust immune responses. Adjuvants are capable of enhancing and/or modulating immune responses by exposing antigens to antigen-presenting cells (APCs) concomitantly with conferring immune activation signals. Few adjuvant systems have been licensed for use in human vaccines, and they mainly stimulate humoral immunity. Thus, there is an unmet demand for the development of safe and efficient adjuvant systems that can also stimulate cell-mediated immunity (CMI). Adjuvants constitute a heterogeneous group of compounds, which can broadly be classified into delivery systems or immunostimulators. Liposomes are versatile delivery systems for antigens, and they can carefully be customized towards desired immune profiles by combining them with immunostimulators and optimizing their composition, physicochemical properties and antigen-loading mode. Immunostimulators represent highly diverse classes of molecules, e.g., lipids, nucleic acids, proteins and peptides, and they are ligands for pattern-recognition receptors (PRRs), which are differentially expressed on APC subsets. Different formulation strategies might thus be required for incorporation of immunostimulators and antigens, respectively, into liposomes, and the choice of immunostimulator should ideally be based on knowledge regarding the specific PRR expression profile of the target APCs. Here, we review state-of-the-art formulation approaches employed for the inclusion of immunostimulators and subunit antigens into liposome dispersion and their optimization towards robust vaccine formulations.

Stimulation with a class A CpG oligonucleotide enhances resistance to infection with feline viruses from five different families

Domestic cats are commonly affected by viral pathogens that induce lengthy infections with fatal outcomes. Prevention of viral propagation is of primordial importance in shelters and catteries, where cats from different backgrounds have narrow contacts. Oligonucleotides (ODN) containing cytosine-phosphate-guanosine motifs of class A (CpG-A) are highly potent synthetic inducers of innate antiviral mechanisms. The aim of this study was to test their ability to modulate innate immune responses and prevent viral replication as stand-alone agents in the domestic cat. CpG-A stimulation of feline peripheral blood mononuclear cells (PBMCs) enhanced their proliferation, increased the presence of co-stimulatory molecules on their surface and influenced their gene expression profiles in an antiviral orientation. Incubation of the supernatants of CpG-A stimulated PBMCs with feline cell lines of epithelial and fibroblastic origin induced expression of the antiviral myxovirus resistance (Mx) gene in these target cells, which also showed enhanced resistance to feline viruses from five distinct families, namely Coronaviridae, Herpesviridae, Caliciviridae, Parvoviridae, and Retroviridae. Most importantly, subcutaneous administration of CpG-A in domestic cats systemically increased the expression of Mx, reaching maximal levels within 24 h. Plasma from treated cats could furthermore inhibit viral replication in vitro. Altogether, our data highlight the promising potential of CpG-A to induce a preventive antiviral state in the cat and to protect feline populations against a broad range of virus infections.

The counter regulatory response induced by CpG oligonucleotides prevents bleomycin induced pneumopathy

Bleomycin (BLM) induces life-threatening pneumonitis and pulmonary fibrosis in 20% of patients, limiting its use as a chemotherapeutic agent. Oligonucleotides expressing immunostimulatory CpG motifs (CpG ODN) stimulate cells that express Toll-like receptor 9 to initiate an inflammatory response. This short-lived inflammation is physiologically suppressed by a counter-regulatory process that peaks five days later. Using a murine model of BLM-induced lung injury, the effect of CpG ODN treatment on pulmonary inflammation, fibrosis and mortality was examined. Administering CpG ODN 5 days before BLM (so that the peak of the counter-regulatory process induced by CpG ODN coincided with BLM delivery) resulted in a dose-dependent reduction in pulmonary toxicity (p < 0.005). Delaying the initiation of therapy until the day of or after BLM administration worsened the inflammatory process, consistent with the counter-regulatory process rather than initial pro-inflammatory response being critical to CpG induced protection. The protection afforded by CpG ODN correlated with reduced leukocyte accumulation and inflammatory cytokine/chemokine production in the lungs. These changes were associated with the increased production of IL-10, a critical element of the counter-regulatory process triggered by CpG ODN, and the concomitant down-regulation of BLM-induced IL-17A and TGF-β1 (which promote pulmonary toxicity). This work represents the first example of the physiologic counter-regulation of TLR induced immune activation being harnessed to block an unrelated inflammatory response.

Liposomal SLA co-incorporated with PO CpG ODNs or PS CpG ODNs induce the same protection against the murine model of leishmaniasis

First generation Leishmania vaccines consisting of whole killed parasites with or without adjuvants have reached phase 3 trial and failed to show enough efficacy mainly due to the lack of an appropriate adjuvant. In this study, the nuclease-resistant phosphorothioate CpG oligodeoxynucleotides (PS CpG) or nuclease-sensitive phosphodiester CpG ODNs (PO CpG) were used as adjuvants to enhance immunogenicity and rate of protection against leishmaniasis. Due to the susceptibility of PO CpG to nuclease degradation, an efficient liposomal delivery system was developed to protect them from degradation. 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid was used because of its unique adjuvanticity and electrostatic interaction with negatively charged CpG ODNs. To evaluate the role of liposomal formulation in protection rate and enhanced immune response, BALB/c mice were immunized subcutaneously with liposomal soluble Leishmania antigens (SLA) co-incorporated with PO CpG (Lip-SLA-PO CpG), Lip-SLA-PS CpG, SLA+PO CpG, SLA+PS CpG, SLA or buffer. As criteria for protection, footpad swelling at the site of challenge, parasite loads, the levels of IFN-γ and IL-4, and the IgG subtypes were evaluated. The groups of mice receiving Lip-SLA-PO CpG or Lip-SLA-PS CpG showed a high protection rate compared with the control groups. In addition, there was no significant difference in immune response generation between mice immunized with PS CpG and the group receiving PO CpG when incorporated into the liposomes. The results suggested that liposomal form of PO CpG might be used instead of PS CpG in future vaccine formulations as an efficient adjuvant.

Efficacy evaluation of live Escherichia coli expression Brucella P39 protein combined with CpG oligodeoxynucleotides vaccine against Brucella melitensis 16M, in BALB/c mice

Brucella is gram-negative bacteria responsible for brucellosis in a wide variety of animals and humans. BALB/c mice were immunized with live Escherichia coli expression the p39 gene of Brucella melitensis, a gene coding for the periplasmic binding protein. Mice were injected with either E. coli BL21 (DE3) pEt15b or E. coli BL21 (DE3) pEt15b-p39 alone or adjuvanted with either CpG oligodeoxynucleotides (CpG ODN) or non-CpG ODN. E. coli BL21 (DE3) pEt15b-p39 with CpG ODN or with non-CpG ODN mice groups showed a significant IFN-γ production and T-cell proliferation as a reaction to P39 antigen. In addition, antibody responses (IgG, IgG1 and IgG2a), were only found in these two mice groups. A higher level of protection against B. melitensis 16M were observed in mice immunized with E. coli BL21 (DE3) pEt15b-p39 and CpG ODN comparing with those immunized with E. coli BL21 (DE3) pEt15b-p39 alone or with non-CpG ODN. No protection against B. melitensis 16M was observed in mice immunized with E. coli BL21 (DE3) pEt15b alone or with the adjuvant. Rev.1 protection at 4 and 8 weeks post-challenge was more effective than that observed with E. coli BL21 (DE3) pEt15b-p39 and CpG ODN.

Cationic liposomes containing soluble Leishmania antigens (SLA) plus CpG ODNs induce protection against murine model of leishmaniasis

Development of an effective vaccine against leishmaniasis is possible due to the fact that individuals cured from cutaneous leishmaniasis (CL) are protected from further infection. First generation Leishmania vaccines consisting of whole killed parasites reached to phase 3 clinical trials but failed to show enough efficacies mainly due to the lack of an appropriate adjuvant. In this study, an efficient liposomal protein-based vaccine against Leishmania major infection was developed using soluble Leishmania antigens (SLA) as a first generation vaccine and cytidine phosphate guanosine oligodeoxynucleotides (CpG ODNs) as an immunostimulatory adjuvant. 1, 2-Dioleoyl-3-trimethylammonium-propane was used as a cationic lipid to prepare the liposomes due to its intrinsic adjuvanticity. BALB/c mice were immunized subcutaneously (SC), three times in 2-week intervals, with Lip-SLA-CpG, Lip-SLA, SLA + CpG, SLA, or HEPES buffer. As criteria for protection, footpad swelling at the site of challenge and spleen parasite loads were assessed, and the immune responses were evaluated by determination of IFN-γ and IL-4 levels of cultured splenocytes, and IgG subtypes. The group of mice that received Lip-SLA-CpG showed a significantly smaller footpad swelling, lower spleen parasite burden, higher IgG2a antibody, and lower IL-4 level compared to the control groups. It is concluded that cationic liposomes containing SLA and CpG ODNs are appropriate to induce Th1 type of immune response and protection against leishmaniasis.

TLR9 agonists: immune mechanisms and therapeutic potential in domestic animals

Toll like receptors (TLRs) are transmembrane glycoproteins that recognize conserved microbial molecules. Engagement of TLRs activates innate and adaptive immunity. TLR-mediated activation of immune cells results in upregulation of cytokines, chemokines and costimulatory molecules. These early innate responses control pathogen spread and initiates adaptive immune responses. Synthetic CpG oligodeoxynucleotides (ODN), agonists for TLR9, had shown great promise as immunotherapeutic agents and vaccine adjuvants in laboratory animal models of infectious disease, allergy and cancer. However, it has become apparent that CpG ODN are less potent immune activators in domestic animals and humans. The disparity in immune responses between rodents and mammals has been mainly attributed to differences in cellular expression of TLR9 in the various species. In this article, our current understanding of the immune mechanisms, as well as the potential applications of CpG ODN will be reviewed, with particular emphasis on domestic animals.

MAGE A3 antigen-specific cancer immunotherapeutic

Non-small-cell lung cancer (NSCLC) and melanoma are devastating diseases with high rates of recurrence. Current clinical recommendations include postoperative adjuvant chemotherapy in stages II and IIIA NSCLC, while there is a debate regarding its clinical benefit in stage IB. Recent Phase II trials have demonstrated a clinical benefit by postoperative vaccine with melanoma-specific antigen A3 (MAGE A3) in NSCLC and in stage IV melanoma. These trials have led to the current Phase III trials. MAGE A3 is a tumor-specific shared antigen that is frequently expressed in lung cancer and melanoma, as well as in few other tumors. Its level is associated with disease burden and with prognosis, while normal tissues do not express it, except the testis and the placenta. This review will summarize the recent developments and clinical experience with the MAGE A3 vaccine.

Mesenteric lymph node cells from neonates present a prominent IL-12 response to CpG oligodeoxynucleotide via an IL-15 feedback loop of amplification

At birth, the immune system is still in development making neonates more susceptible to infections. The recognition of microbial ligands is a key step in the initiation of immune responses. It can be mimicked to stimulate the immune system by the use of synthetic ligands recognising pattern recognition receptors. In human and mouse, it has been found that neonatal cytokine responses to toll-like receptor (TLR) ligands differ in many ways from those of adults but the relevant studies have been limited to cord blood and spleen cells. In this study, we compared the responses in neonate and adult sheep to CpG oligodeoxynucleotides (ODN), a TLR9 ligand, in both a mucosal and a systemic organ. We observed that in response to CpG-ODN more IL-12 was produced by neonatal than adult sheep cells from mesenteric lymph nodes (MLN) and spleen. This higher IL-12 response was limited to the first 20 days after birth for MLN cells but persisted for a longer period for spleen cells. The major IL-12-producing cells were identified as CD14⁺CD11b⁺. These cells were poor producers of IL-12 in response to direct stimulation with CpG-ODN and required the cooperation of other MLN cells. The difference in response to CpG-ODN between neonates and adults can be attributed to both a higher proportion of CD14⁺CD11b⁺ cells in neonate lambs and their higher capacity to produce IL-15. The IL-15 increases IL-12 production by an amplifying feedback loop involving CD40.

Subcutaneous, but not intratracheal administration of the TLR9 agonist, CpG DNA transiently reduces parainfluenza-3 virus shedding in newborn lambs

Synthetic oligodeoxynucleotides (ODN) containing CpG motifs signal through TLR9 and activate innate immunity resulting in protection against a variety of parasitic, bacterial and viral pathogens in mouse models. However, few studies have demonstrated protection in humans and large animals. In the present investigations, we evaluated protection by CpG ODN in a parainfluenza-3 (PI-3) virus infection in neonatal lambs. Subcutaneous (SC) injection of CpG ODN induced high levels of 2'5'-A synthetase and significantly reduced PI-3 virus shedding in newborn lambs. Furthermore, pre-treatment of newborn lambs with SC CpG ODN 2 days, but not 6 days prior to the virus challenge was protective. In contrast, intratracheal (IT) administration of CpG ODN induced 2'5'-A synthetase but had no significant impact on PI-3 virus shedding in nasal secretions. We conclude that a systemic administration of CpG ODN and the timing of the treatment are critical for the protection of neonatal lambs against a respiratory viral infection.

Immune Mechanisms and Therapeutic Potential of CpG Oligodeoxynucleotides

Unmethylated CpG motifs in bacterial DNA and synthetic oligodeoxynucleotides activate immune cells that express Toll-like Receptor 9. Activation through this receptor triggers cellular signaling that leads to production of a proinflammatory and a Th1-type, antigen-specific immune response. The immunostimulatory effects of CpG oligodeoxynucleotides confer protection against infectious disease, allergy and cancer in animal models, and clinical trials have been initiated. However, CpG oligodeoxynucleotides may exacerbate disease in some situations. We will review current concepts in the mechanisms of activating Toll-like Receptor 9 with CpG oligodeoxynucleotides and highlight opportunities for using large animal models to better determine the mechanisms of action.

Toll-like receptor 9 agonists promote IL-8 and TGF-beta1 production via activation of nuclear factor kappaB in PC-3 cells

Chronic infection and resulting inflammation promote tumor development and progression, and Toll-like receptors (TLRs) may play an important role in this process. The aim of this study was to determine whether CpG oligonucleotides (CpG-ODN), which are Toll-like receptor 9 (TLR9) agonists, can promote inflammatory cytokines release from the prostate cancer PC-3 cells through activation of nuclear factor-kappaB (NF-kappaB). Flow cytometry, semiquantitative real-time reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and immunofluorescence analysis were used to detect the transforming growth factor-beta1 (TGF-beta1) and interleukin-8 (IL-8) release and NF-kappaB activation in PC-3 cells after CpG-ODN stimulation. CpG-ODN promoted the expression and secretion of immunosuppressive cytokines TGF-beta1 and IL-8 from PC-3 cells. In addition, after CpG-ODN stimulation, NF-kappaB nuclear translocation was also observed in PC-3 cells, contributing to CpG-induced upregulation of IL-8 and TGF-beta1. Thus, TLR9 agonists may promote IL-8 and TGF-beta1 production in human prostate cancer cells through NF-kappaB activation.

CpG oligodeoxynucleotides augment the murine immune response to the Yersinia pestis F1-V vaccine in bubonic and pneumonic models of plague

The current U.S. Department of Defense candidate plague vaccine is a fusion between two Yersinia pestis proteins: the F1 capsular protein, and the low calcium response (Lcr) V-protein. We hypothesized that an immunomodulator, such as CpG oligodeoxynucleotide (ODN)s, could augment the immune response to the plague F1-V vaccine in a mouse model for plague. CpG ODNs significantly augmented the antibody response and efficacy of a single dose of the plague vaccine in murine bubonic and pneumonic models of plague. In the latter study, we also found an overall significant augmentation the immune response to the individual subunits of the plague vaccine by CpG ODN 2006. In a long-term, prime-boost study, CpG ODN induced a significant early augmentation of the IgG response to the vaccine. The presence of CpG ODN induced a significant increase in the IgG2a subclass response to the vaccine up to 5 months after the boost. Our studies showed that CpG ODNs significantly augmented the IgG antibody response to the plague vaccine, which increased the probability of survival in murine models of plague (P<0.0001).

Immune modulatory oligonucleotides in the prevention and treatment of allergen-induced eustachian tube dysfunction in the animal model

This article reviews the current literature investigating the applications and success of immune modulatory oligonucleotides as immunotherapy to treat and prevent allergen-induced eustachian tube dysfunction in animal models. Synthetic DNA-based immunotherapy agents composed of unmethylated cytosine-guanine dinucleotides (CpG ODNs) that bind to Toll-like receptors have been found to have tremendous potential as therapeutic agents and adjuvants. CpG ODNs can induce a shift in the cytokine profile and immune response that favors the T-helper type 1 pathway and suppresses the T-helper type 2 pathway. This makes CpG ODNs promising candidates for treating allergic diseases. Current CpG ODN studies have demonstrated prevention and treatment of acute allergen inflammation of the eustachian tube in an animal model of otitis media. Immune modulatory oligonucleotides in immunotherapy, administered systemically or topically, have been shown to be safe and effective in the animal model.

Immunotherapy with CpG oligonucleotides and antibodies to TNF-alpha rescues neonatal mice from lethal arenavirus-induced meningoencephalitis

Viral encephalitides are life-threatening diseases in neonates partly due to the irreversible damage inflammation causes to the CNS. This study explored the role of proinflammatory cytokines in the balance between controlling viral replication and eliciting pathologic immune responses in nonlytic viral encephalitis. We show that neonatal mice challenged with arenavirus Tacaribe (TCRV) develop a meningoencephalitis characterized by high IFN-gamma and TNF-alpha levels and mild T cell infiltration. Neutralization of the TNF-alpha using mAb was associated with lower chemokine expression, reduced T cell infiltration, and lower levels of IFN-gamma, and TNF-alpha in the CNS and led to 100% survival. Moreover, treatment with Abs to TNF-alpha improved mobility and increased survival even after the mice developed bilateral hind limb paralysis. Of note, animals treated with anti-TNF-alpha Abs alone did not clear the virus despite generating Abs to TCRV. Direct activation of the innate immune response using CpG oligodeoxynucleotides in combination with anti-TNF-alpha Abs resulted in 100% survival and complete viral clearance. To our knowledge, this is the first demonstration of the use of innate immune modulators plus Abs to TNF-alpha as therapeutics for a lethal neurotropic viral infection.

An optimized electrofusion-based protocol for generating virus-specific human monoclonal antibodies

We sought to develop and optimize a hybridoma-based technology for generating human hybridomas that secrete virus-specific monoclonal antibodies for clinical diagnosis and therapy. We developed a novel electrofusion protocol for efficiently fusing Epstein-Barr virus (EBV)-transformed human B cells with myeloma partners. We tested seven myeloma cell lines and achieved highest efficiency when the HMMA 2.5 line was used. We optimized the electrofusion process by improving cell treatments before and after electrofusion as well as varying cell ratios, fusion medium and other experimental parameters. Our fusion efficiency increased remarkably to 0.43%, a significant improvement over the efficiency of previous PEG-based or other electrofusion methods. Using the optimized protocol, we obtained human hybridomas that secrete fully human monoclonal antibodies against two major human respiratory pathogens: respiratory syncytial virus (RSV) and an influenza H3N2 vaccine virus strain. In conclusion, we have developed an efficient and routine approach for the generation of human hybridomas secreting functional human virus-specific monoclonal antibodies.

Synthetic oligonucleotides as modulators of inflammation

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs mimic the immunostimulatory activity of bacterial DNA. CpG ODN directly stimulate human B cells and plasmacytoid dendritic cells, promote the production of Th1 and proinflammatory cytokines, and trigger the maturation/activation of professional APC. CpG ODN are finding use in the treatment of cancer, allergy, and infection. In contrast, ODN containing multiple TTAGGG motifs mimic the immunosuppressive activity of self-DNA, down-regulating the production of proinflammatory and Th1 cytokines. Preclinical studies suggest that "suppressive" ODN may slow or prevent diseases characterized by pathologic immune stimulation, including autoimmunity and septic shock. Extensive studies in animal models suggest that the therapeutic value of CpG and TTAGGG ODN may be optimized by early administration.

Review: variability of host-pathogen interaction

The course of every infection is different. The same pathogen can lead to subclinical, mild, severe or lethal infections in individuals. But is this just chance or determined by individual differences--on the side of the host as well as on the side of the pathogen? If so, we might need to consider these variations for treatment decisions. Indeed, we now understand that genetic polymorphisms and health status represent inborn and acquired risk factors. Similarly, pathogens impress with an increasing number of already identified virulence factors and host response modifiers. The emerging, more complex, view of the factors determining course and outcome of infections promises to enable more tailored and thus, hopefully, more effective treatment decisions.

Attenuated cytokine responses in porcine lymph node cells stimulated with CpG DNA are associated with low frequency of IFNalpha-producing cells and TLR9 mRNA expression

The immune stimulatory effects of synthetic CpG DNA, on porcine peripheral blood mononuclear cells (PBMC) have been reported, but little is known about CpG-induced responses in other lymphoid tissues of pigs. We investigated innate immune responses induced by CpG DNA in cells from blood, lymph nodes (LN) and spleens of pigs. Porcine PBMC and lymph node cells (LNC) were stimulated in vitro with three classes (A-, B- and C-class) of CpG oligodeoxynucleotides (ODNs), and a non-CpG control ODN. All three classes of CpG ODNs induced significant production of IFNalpha, TNFalpha, IL-1, IL-6 and IL-12 in PBMC. In contrast, in LNC, only IL-12 was stimulated by all three classes of CpG ODNs, while IFNalpha, and IL-6 were induced by A- and C-class ODNs. No TNFalpha was induced in LNC by any of the ODNs. Significant lymphocyte proliferation was induced in PBMC by all three classes of CpG ODNs and non-CpG control. However, in LNC, B- and C-class ODNs induced significant proliferation, while no proliferation was seen with A-class and non-CpG control ODN. All three classes of ODNs induced NK-like cytotoxicity in PBMC and spleen cells, but were less effective in inducing NK cytotoxicity in LNC. We then investigated the reasons for the relatively poor CpG-induced responses in LNC. Our investigations revealed that LNC had a lower frequency of IFNalpha-secreting cells and expressed low levels of TLR9 mRNA compared to PBMC. We conclude that the lower number of IFNalpha-secreting cells and receptor expression may contribute to the attenuated responses in LNC following stimulation with CpG ODN.

Coencapsulation of CpG oligodeoxynucleotides with recombinant Leishmania major stress-inducible protein 1 in liposome enhances immune response and protection against leishmaniasis in immunized BALB/c mice

CpG oligodeoxynucleotides (CpG ODN) have been shown to have potent adjuvant activity for a wide range of antigens. The purpose of this study was to determine the potential benefit of using liposomes as a delivery vehicle to enhance the adjuvant activity of CpG ODN with Leishmania major stress-inducible protein 1 (LmSTI1) antigen in induction of the Th1 response in a murine model of leishmaniasis. BALB/c mice were immunized subcutaneously three times in 3-week intervals with liposomal recombinant LmSTI1 (Lip-rLmSTI1), rLmSTI1 coencapsulated with CpG ODN in a liposome (Lip-rLmSTI1-CpG ODN), rLmSTI1 plus CpG ODN in phosphate-buffered saline (PBS), rLmSTI1 plus non-CpG ODN in PBS, rLmSTI1 in PBS, empty liposome, or PBS. The intensity of infection induced by L. major promastigote challenge was measured by footpad swelling. A significant (P < 0.001) inhibition of infection in mice immunized with Lip-rLmSTI1-CpG ODN was shown compared to the other groups, and no parasite was detected in the spleens of this group 14 weeks after challenge. The highest immunoglobulin G2a (IgG2a) titer and the highest IgG2a/IgG1 ratio were also shown in the sera of mice immunized with Lip-rLmSTI1-CpG ODN before and 14 weeks after challenge. The results indicated the superiority of CpG ODN in its liposomal form over its soluble form to induce the Th1 response when used in association with rLmSTI1 antigen. It seems that using a liposome delivery system carrying CpG ODN as an adjuvant coencapsulated with Leishmania antigen plays an important role in vaccine development strategies against leishmaniasis.

V3 CTL epitope density in a single recombinant molecule antigen differentially affects the number and activity of primary and memory CD8+ T cells

Previous studies have found the close correlation between epitope density and epitope-specific response, which have shown that high epitope density in a single recombinant protein molecule significantly enhances the humoral response and protective immunity. However, it has not been determined whether this kind of high epitope density could also significantly influence T cell response. Based on this, a series of recombinant DNA and proteins were designed and prepared. Each molecule consists of various copy numbers of the V3 CTL epitope on HIV-1 gp120 (one, two, four and eight copies). Our results show clearly that different V3-epitope densities in just one single DNA or protein molecules have respectively different effects on the number and activity of both primary and memory T cells. Interestingly, this effect is more complex than that on the B cells: epitope density in one plasmid or protein antigen affects the number, not the cytotoxic avidity, of primary CD8+ T cells, but affects both the number and cytotoxic avidity of memory CD8+ T cells. It indicates epitope density in the antigen is an important consideration to optimize T cell response induction and may facilitate the development of effective T cell-based anti-virus vaccines.

MF59 is a safe and potent vaccine adjuvant that enhances protection against influenza virus infection

In preclinical studies, MF59 adjuvant offered improved protection against influenza virus challenge and significantly reduced the viral load in the lungs of challenged mice. In humans, MF59 is a safe and potent vaccine adjuvant that has been licensed in more than 20 countries (Fluad [Novartis Vaccines and Diagnostics Inc., MA, USA]). The safety profile of an MF59-adjuvanted vaccine is well established through a large safety database. MF59 adjuvant has had a significant impact on the immunogenicity of influenza vaccines in the elderly and in adults who are chronically ill. MF59 has also been shown to have a significant impact on the immunogenicity of pandemic influenza vaccines. MF59 allows for broader cross-reactivity against viral strains not included in the vaccine. MF59 has been shown to be more potent for both antibody and T-cell responses than aluminum-based adjuvants. MF59 has broad potential to be used as a safe and effective vaccine adjuvant for a wide range of vaccine types.

Immune modulatory oligonucleotides in the prevention and treatment of OVA-induced eustachian tube dysfunction in rats

BACKGROUND

Otitis media with effusion (OME) is often associated with allergies. Immune modulatory oligonucleotides (IMO) mediate allergic inflammation and may therefore be efficacious in the treatment of airway inflammation.

OBJECTIVE

To evaluate the role of an IMO via transtympanic mucosal application in prevention and treatment of ovalbumin-induced OME.

DESIGN

Forty brown Norway rats were divided into control and treatment groups. Eustachian tube dysfunction was evaluated by passive opening pressures, passive closing pressures, active clearance of negative pressure, and mucociliary clearance transit time.

RESULTS

Rats who underwent IMO treatment required 50% less pressure to open and close the eustachian tube (P < 0.05) and were able to actively clear 50% more negative pressure than the ovalbumin-control rats (P < 0.001). The treatment rats' mucociliary clearance time was half that of the control group (P < 0.001).

CONCLUSION

IMO via transtympanic application can prevent and treat allergy-induced eustachian tube dysfunction in rats. IMO may offer substantial promise in the future management of OME.

Molecular mechanism of immune response induced by foreign plasmid DNA after oral administration in mice

AIM: To study immune response induced by foreign plasmid DNA after oral administration in mice.

METHODS: Mice were orally administered with 200 μg of plasmid pcDNA3 once and spleen was isolated 4 h and 18 h after administration. Total RNA was extracted from spleen and gene expression profile of BALB/c mice spleen was analyzed by using Affymetrix oligonucleotide GeneChip. Functional cluster analysis was conducted by GenMAPP software.

RESULTS: At 4 h and 18 h after oral plasmid pcDNA3 administration, a number of immune-related genes, including cytokine and cytokine receptors, chemokines and chemokine receptor, complement molecule, proteasome, histocompatibility molecule, lymphocyte antigen complex and apoptotic genes, were up-regulated. Moreover, MAPPFinder results also showed that numerous immune response processes were up-regulated. In contrast, the immunoglobulin genes were down-regulated.

CONCLUSION: Foreign plasmid DNA can modulate the genes expression related to immune system via the gastrointestinal tract, and further analysis of the related immune process may help understand the molecular mechanisms of immune response induced by foreign plasmid via the gastrointestinal tract.

Systemic innate immune responses following intrapulmonary delivery of CpG oligodeoxynucleotides in sheep

Mucosal delivery of CpG oligodeoxynucleotide (ODN) in mice has been shown to induce potent innate immunostimulatory responses and protection against infection. We evaluated the efficacy of CpG ODN in stimulating systemic innate immune responses in sheep following delivery to the pulmonary mucosa. Intrapulmonary (IPM) administration of B-Class CpG ODN in saline induced transient systemic responses which included increased rectal temperatures, elevated serum 2'5'-A synthetase and haptoglobin concentrations. The ODN dose required to induce detectable systemic responses following IPM delivery could be reduced by approximately 80% if the CpG ODN was administered in 30% emulsigen instead of saline. Intrapulmonary B-Class CpG ODN formulated in 30% emulsigen produced similar effects when compared to those seen following SC injection. These responses were CpG ODN-specific since control GpC ODN did not induce any detectable response. Intrapulmonary administration of both B-Class and the newly described C-Class CpG ODN produced similar effects indicating that both classes of CpG ODN were comparably effective in stimulating innate immune system following mucosal delivery. Administration of CpG ODN directly into the lungs or delivery of CpG ODN via an intratracheal (IT) infusion also produced similar systemic responses. These observations support the conclusion that mucosal delivery of CpG ODN is an effective route for induction of systemic acute phase responses and antiviral effector molecules in large animals, and may be helpful in controlling systemic infections.

The role of immunomodulatory oligonucleotides in prevention of OVA-induced Eustachian tube dysfunction

OBJECTIVE

To evaluate the potential role of immunomodulatory oligonucleotides (IMO) in the prevention of OVA-induced Eustachian tube dysfunction (ETD) in a rat model.

METHODS

Brown-Norway rats were sensitized to ovalbumin (OVA) and randomized to receive pre-treatment with IMO or phosphate buffered saline (PBS). After systemic sensitization, subjects received a transtympanic OVA challenge followed by evaluation of the Eustachian tube's dynamic function.

RESULTS

Pre-treatment of OVA sensitized animals with IMO normalized passive opening and closing Eustachian tube pressures, improved active clearance of negative pressure in the middle ear, and resulted in reduced mean mucociliary transit times compared to untreated OVA-sensitized animals (P<0.001).

CONCLUSION

These data demonstrate that pre-treatment with IMO prevent OVA-induced ETD in the rat. IMO treatment in the future may offer considerable promise in the management of OME in children.

Response of nitric oxide production to CpG oligodeoxynucleotides in turkey and chicken peripheral blood monocytes

We evaluated the innate immune response to various synthetic CpG-containing oligodeoxynucleotides (CpG ODNs) by measuring nitric oxide production in the peripheral blood monocytes from turkey poults. The results indicate that the presence of the CpG dinucleotide in ODNs was a prerequisite for activation of turkey monocytes and induction of nitric oxide (NO) synthesis. CpG motifs and sequence structure of the ODNs were also found to influence stimulatory activity greatly. The most potent CpG ODN to induce NO synthesis in turkey monocytes was human-specific CpG ODN M362, followed by CpG ODN 2006 (human), CpG ODN#17 (chicken) and CpG ODN 1826 (mouse). The optimal CpG motif for NO induction was GTCGTT. Phosphorothioate modification of CpG ODNs also significantly increased stimulatory activity. Compared with chicken monocytes, turkey monocytes appeared to be less sensitive to CpG motif variation, whereas chicken monocytes were found to respond more strictly to human-specific CpG ODNs or ODNs that contain GTCGTT motifs.