Oral QS-21 requires early IL-4 help for induction of mucosal and systemic immunity

Subcutaneous, Oral, and Intranasal Immunization of BALB/c Mice with Leishmania infantum K39 Antigen Induces Non-Protective Humoral Immune Response

Visceral leishmaniasis is a high-burden disease caused by parasites of the Leishmania genus. The K39 kinesin is a highly antigenic protein of Leishmania infantum, but little is known about the immune response elicited by this antigen. We evaluated the humoral immune response of female BALB/c mice (n = 6) immunized with the rK39-HFBI construct, formed by the fusion of the K39 antigen to a hydrophobin partner. The rK39-HFBI construct was administered through subcutaneous, oral, and intranasal routes using saponin as an adjuvant. We analyzed the kinetics of IgG, IgG1, and IgG2a production. The groups were then challenged by an intravenous infection with L. infantum promastigote cells. The rK39-HFBI antigen-induced high levels of total IgG (p < 0.05) in all groups, but only the subcutaneous route was associated with increased production of IgG1 and IgG2a 42 days after immunization (p < 0.05), suggesting a potential secondary immune response following the booster dose. There was no reduction in the splenic parasite load; thus, the rK39-HFBI failed to protect the mice against infection under the tested conditions. The results presented here demonstrate that the high antigenicity of the K39 antigen does not contribute to a protective immune response against visceral leishmaniasis.

Discrepancies in the German Pharmacopoeia procedure for quality control of Quillaja saponin extracts

This study focused on the evaluation of Quillaja saponin extracts with the additional quality designation DAB-which means the abbreviation of the German Pharmacopoeia (Deutsches Arzneibuch). This label suggests that Quillaja saponin extracts marked in this way are of pharmacopoeial quality and thus stand out from other Quillaja saponin extracts. The DAB ninth edition listed Quillaia saponin as a reagent. According to DAB, its quality must be checked by thin-layer chromatography (TLC), and three closely spaced zones in a defined retention factor (Rf) interval specify the saponin reagent. All the Quillaja saponin extracts obtained from different manufacturers and labeled as DAB quality complied with the TLC test. However, the analysis with high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (HPLC-Q-ToF-MS) clearly showed additionally an intense peak pattern of Madhuca saponins in all measured samples. The TLC test for Mahua seed cake, which is the press residue from Madhuca longifolia, surprisingly showed the same three closely spaced zones in the defined Rf interval. The three zones could be identified as Mi-saponins from Madhuca after scraping and extracting them from the stationary phase of the TLC plate and subsequent measurement by HPLC-Q-ToF-MS. Therefore, the specification of the saponin reagent in DAB characterizes erroneously Madhuca saponins that are not listed as a saponin plant source for the saponin reagent.

Role of pharmaceutical sciences in future drug discovery

The recent emergence of COVID-19 influenced the layman’s knowledge of drugs. Although several drugs have been discovered serendipitously, research has moved to the next-generation era of drug discovery. The use of drugs is inevitable and they have become lifesavers in the present era. Although research from different scientific backgrounds has supported the translational research of drug discovery, the prime role of pharmacy has to be remembered. Here we have summarized the role of some important subjects in pharmacy education, which have paved different ways in drug discovery and development.

Oral vaccination stimulates neutrophil functionality and exerts protection in a Mycobacterium avium subsp. paratuberculosis infection model

Mycobacterium avium subsp. paratuberculosis (Map) causes paratuberculosis (PTB), a granulomatous enteritis in ruminants that exerts high economic impact on the dairy industry worldwide. Current vaccines have shown to be cost-effective against Map and in some cases confer beneficial non-specific effects against other pathogens suggesting the existence of trained immunity. Although Map infection is mainly transmitted by the fecal-oral route, oral vaccination has not been deeply studied. Therefore, the aim of this study was to compare the oral route with a set of mycobacterial and non-mycobacterial vaccines with a subcutaneously administered commercially available vaccine. Training effects on polymorphonuclear neutrophils (PMNs) and homologous and heterologous in vivo protection against Map were investigated in the rabbit infection model. Oral vaccination with inactivated or live vaccines was able to activate mucosal immunity as seen by elevation of serum IgA and the expression of IL4 in peripheral blood mononuclear cells (PBMCs). In addition, peripheral PMN phagocytosis against Map was enhanced by vaccination and extracellular trap release against Map and non-related pathogens was modified by both, vaccination and Map-challenge, indicating trained immunity. Finally, PBMCs from vaccinated animals stimulated in vitro with Map antigens showed a rapid innate activation cytokine profile. In conclusion, our data show that oral vaccination against PTB can stimulate neutrophil activity and both innate and adaptive immune responses that correlate with protection.

The Phagosome-Lysosome Fusion Is the Target of a Purified Quillaja saponin Extract (PQSE) in Reducing Infection of Fish Macrophages by the Bacterial Pathogen Piscirickettsia salmonis

Piscirickettsia salmonis, the etiological agent of Piscirickettsiosis, is a Gram-negative and facultative intracellular pathogen that has affected the Chilean salmon industry since 1989. The bacterium is highly aggressive and can survive and replicate within fish macrophages using the Dot/Icm secretion system to evade the host’s immune response and spread systemically. To date, no efficient control measures have been developed for this disease; therefore, the producers use large amounts of antibiotics to control this pathogen. In this frame, this work has focused on evaluating the use of saponins from Quillaja saponaria as a new alternative to control the Piscirickettsiosis. It has been previously reported that purified extract of Q. saponaria (PQSE) displays both antimicrobial activity against pathogenic bacteria and viruses and adjuvant properties. Our results show that PQSE does not present antimicrobial activity against P. salmonis, although it reduces P. salmonis infection in an in vitro model, promoting the phagosome–lysosome fusion. Additionally, we demonstrate that PQSE modulates the expression of IL-12 and IL-10 in infected cells, promoting the immune response against the pathogen and reducing the expression of pathogen virulence genes. These results together strongly argue for specific anti-invasion and anti-intracellular replication effects induced by the PQSE in macrophages.

Saponins from Quillaja saponaria and Quillaja brasiliensis: Particular Chemical Characteristics and Biological Activities

Quillaja saponaria Molina represents the main source of saponins for industrial applications. Q. saponaria triterpenoids have been studied for more than four decades and their relevance is due to their biological activities, especially as a vaccine adjuvant and immunostimulant, which have led to important research in the field of vaccine development. These saponins, alone or incorporated into immunostimulating complexes (ISCOMs), are able to modulate immunity by increasing antigen uptake, stimulating cytotoxic T lymphocyte production (Th1) and cytokines (Th2) in response to different antigens. Furthermore, antiviral, antifungal, antibacterial, antiparasitic, and antitumor activities are also reported as important biological properties of Quillaja triterpenoids. Recently, other saponins from Q. brasiliensis (A. St.-Hill. & Tul.) Mart. were successfully tested and showed similar chemical and biological properties to those of Q. saponaria barks. The aim of this manuscript is to summarize the current advances in phytochemical and pharmacological knowledge of saponins from Quillaja plants, including the particular chemical characteristics of these triterpenoids. The potential applications of Quillaja saponins to stimulate further drug discovery research will be provided.

Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection

Vaccination is the process of administering immunogenic formulations in order to induce or harness antigen (Ag)-specific antibody and T cell responses in order to protect against infections. Important successes have been obtained in protecting individuals against many deleterious pathological situations after parenteral vaccination. However, one of the major limitations of the current vaccination strategies is the administration route that may not be optimal for the induction of immunity at the site of pathogen entry, i.e., mucosal surfaces. It is now well documented that immune responses along the genital, respiratory, or gastrointestinal tracts have to be elicited locally to ensure efficient trafficking of effector and memory B and T cells to mucosal tissues. Moreover, needle-free mucosal delivery of vaccines is advantageous in terms of safety, compliance, and ease of administration. However, the quest for mucosal vaccines is challenging due to (1) the fact that Ag sampling has to be performed across the epithelium through a relatively limited number of portals of entry; (2) the deleterious acidic and proteolytic environment of the mucosae that affect the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic environment of mucosae, which requires the addition of adjuvants to elicit efficient effector immune responses. Until now, only few mucosally applicable vaccine formulations have been developed and successfully tested. In animal models and clinical trials, the use of lipidic structures such as liposomes, virosomes, immune stimulating complexes, gas-filled microbubbles and emulsions has proven efficient for the mucosal delivery of associated Ags and the induction of local and systemic immune reponses. Such particles are suitable for mucosal delivery because they protect the associated payload from degradation and deliver concentrated amounts of Ags via specialized sampling cells (microfold cells) within the mucosal epithelium to underlying antigen-presenting cells. The review aims at summarizing recent development in the field of mucosal vaccination using lipid-based particles. The modularity ensured by tailoring the lipidic design and content of particles, and their known safety as already established in humans, make the continuing appraisal of these vaccine candidates a promising development in the field of targeted mucosal vaccination.

Enhanced mucosal immune responses against tetanus toxoid using novel delivery system comprised of chitosan-functionalized gold nanoparticles and botanical adjuvant: characterization, immunogenicity, and stability assessment

Approaches based on combined use of delivery systems and adjuvants are being favored to maximize efficient mucosal delivery of antigens. Here, we describe a novel delivery system comprised of chitosan-functionalized gold nanoparticles (CsAuNPs) and saponin-containing botanical adjuvant; Asparagus racemosus extract (ARE) for oral delivery of tetanus toxoid (TT). A significant increase in TT-specific IgG (34.53-fold) and IgA (43.75-fold) was observed when TT-CsAuNPs were formulated with ARE (TT-ARE-CsAuNPs). The local IgA immune responses for TT also showed a significant increase (106.5-fold in intestine washes and 99.74-fold in feces) with ARE-based formulations as compared with plain TT group. No effect of ARE was observed on size, charge, and loading properties of CsAuNPs. Additionally, no effect of ARE and CsAuNPs was observed on antigenicity and secondary structure of TT as determined by fluorescence, circular dichroism, and Fourier transform infrared spectroscopy. The stability studies demonstrated excellent stability profile of formulation at recommended storage conditions. The study establishes the possible role of immunomodulatory adjuvants in particulate delivery systems for mucosal delivery of vaccines.

Alternative inactivated poliovirus vaccines adjuvanted with Quillaja brasiliensis or Quil-a saponins are equally effective in inducing specific immune responses

Inactivated polio vaccines (IPV) have an important role at the final stages of poliomyelitis eradication programs, reducing the risks associated with the use of attenuated polio vaccine (OPV). An affordable option to enhance vaccine immunogenicity and reduce costs of IPV may be the use of an effective and renewable adjuvant. In the present study, the adjuvant activity of aqueous extract (AE) and saponin fraction QB-90 from Quillaja brasiliensis using poliovirus antigen as model were analyzed and compared to a preparation adjuvanted with Quil-A, a well-known saponin-based commercial adjuvant. Experimental vaccines were prepared with viral antigen plus saline (control), Quil-A (50 µg), AE (400 µg) or QB-90 (50 µg). Sera from inoculated mice were collected at days 0, 28, 42 and 56 post-inoculation of the first dose of vaccine. Serum levels of specific IgG, IgG1 and IgG2a were significantly enhanced by AE, QB-90 and Quil-A compared to control group on day 56. The magnitude of enhancement was statistically equivalent for QB-90 and Quil-A. The cellular response was evaluated through DTH and analysis of IFN-γ and IL-2 mRNA levels using in vitro reestimulated splenocytes. Results indicated that AE and QB-90 were capable of stimulating the generation of Th1 cells against the administered antigen to the same extent as Quil-A. Mucosal immune response was enhanced by the vaccine adjuvanted with QB-90 as demonstrated by increases of specific IgA titers in bile, feces and vaginal washings, yielding comparable or higher titers than Quil-A. The results obtained indicate that saponins from Q. brasiliensis are potent adjuvants of specific cellular and humoral immune responses and represent a viable option to Quil-A.

Quillaja saponaria extract as mucosal adjuvant with chitosan functionalized gold nanoparticles for mucosal vaccine delivery: stability and immunoefficiency studies

Carrier mediated delivery of vaccines along with adjuvants can possibly address the issue related to oral vaccines like inadequate immune potentiation. In this study, chitosan functionalized gold nanoparticles (CsAuNPs) were used as a carrier for the model antigen tetanus toxoid (TT) along with immunostimulant Quillaja saponaria extract (QS). Physicochemical properties (size, zeta potential, pH value) of formulation were investigated as stability indicating parameters. The synthesized CsAuNPs were spherical in shape, around 40 nm in size, positively charged (around +35 mV) and had TT and QS payload of 65% and 0.01%, respectively. Formulation parameters did not alter the secondary structure of TT, as determined by FTIR, fluorescence and CD spectroscopy. Antigen specificity, determined by an ELISA, was also not compromised. The CsAuNPs conferred protection to TT against gastric hydrolysis as studied in vitro. TT-QS-CsAuNPs induced up to 28-fold immune responses compared to control formulations (TT, TT-QS) after oral administration of formulations in BALB/c mice. The immune responses were quantified by measuring the TT-specific IgG and IgA titers using ELISA. Findings herein demonstrate that co-delivery of TT and QS with functionalized CsAuNPs promotes better systemic and local immune responses and hence can be considered as a sound approach for oral vaccine delivery.

Mucosal vaccine design and delivery

Mucosal surfaces are a major portal of entry for many human pathogens that are the cause of infectious diseases worldwide. Vaccines capable of eliciting mucosal immune responses can fortify defenses at mucosal front lines and protect against infection. However, most licensed vaccines are administered parenterally and fail to elicit protective mucosal immunity. Immunization by mucosal routes may be more effective at inducing protective immunity against mucosal pathogens at their sites of entry. Recent advances in our understanding of mucosal immunity and identification of correlates of protective immunity against specific mucosal pathogens have renewed interest in the development of mucosal vaccines. Efforts have focused on efficient delivery of vaccine antigens to mucosal sites that facilitate uptake by local antigen-presenting cells to generate protective mucosal immune responses. Discovery of safe and effective mucosal adjuvants are also being sought to enhance the magnitude and quality of the protective immune response.

Formulation design considerations for oral vaccines

Whilst oral vaccination is a potentially preferred route in terms of patient adherence and mass vaccination, the ability to formulate effective oral vaccines remains a challenge. The primary barrier to oral vaccination is effective delivery of the vaccine through the GI tract owing to the many obstacles it presents, including low pH, enzyme degradation and bile-salt solubilization, which can result in breakdown/deactivation of a vaccine. For effective immune responses after oral administration, particulates need to be taken up by the M cells however, these are few in number. To enhance M-cell uptake, particle characteristics can be optimized with particle size, surface charge, targeting groups and bioadhesive properties all being considerations. Yet improved uptake may not translate into enhanced immune responses and formulating particulates with inherent adjuvant properties can offer advantages. Within this article, we establish the options available for consideration when building effective oral particulate vaccines.

Soybean meal induces intestinal inflammation in common carp (Cyprinus carpio L.)

The development of soybean meal (SBM) induced enteritis in the hindgut of the omnivorous common carp (Cyprinus carpio L.). The developed condition was assessed when carp, continuously fed on animal protein, were transferred to a diet in which 20% of the protein was replaced by SBM. After week 1, most of the inflammation parameters were already present, but at week 3, a strong aggravation of the condition was observed which included a shortening of the mucosal folds, the disappearance of the supranuclear vacuoles, an increased number of goblet cells, a thickened lamina propria and sub-epithelial mucosa with increased numbers of basophilic granulocytes as well as a decreased uptake capacity of enterocytes (impaired endocytosis and microvilli). Contrary to previous observations made with respect to Atlantic salmon, common carp start to recover from the fourth to the fifth week after switching to SBM feeding. At this stage, the supranuclear vacuoles refill and most of the parameters revert to basal levels. During the enteritis process, a real-time quantitative PCR analysis was conducted to measure the expression of inflammatory and anti-inflammatory cytokine genes in the isolated intraepithelial lymphocytes (IEL). The pro-inflammatory interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha1 (TNF-alpha1) genes were up-regulated during the inflammation process while the anti-inflammatory interleukin 10 (IL-10) was down-regulated after an initial up-regulation at week 1. Transforming growth factor beta (TGF-beta) expression showed an up-regulation from week 3 onwards despite the high Ct value and the low primer efficiency shown. This study confirms the contribution of IEL (mainly T-like cells) and basophils in the enteritis process. In addition, the results show a clear involvement of up- and down-regulated cytokine genes in both the onset and recovery of the SBM-induced enteritis in the hindgut of carp.

Adjuvant formulations possess differing efficacy in the potentiation of antibody and cell mediated responses to a human malaria vaccine under selective immune genes knockout environment

Infections and chronic diseases can alter the host's immunological balance or result in immunodeficiencies. We hypothesize that this may also affect the performance of vaccine adjuvants. Accordingly, the potency and adjuvanticity of eight adjuvant formulations based on Montanide ISA720, MF59, monophosphoryl lipid A (MPL), QS21 (saponin derivative), MPL-SE (stable emulsion of a MPL derivative), and MPL-AF (MPL in aqueous formulation) were studied in immune gene knockout mice, IFN-gamma -/-, IL-4 -/-, and STAT6 -/-, using the P. falciparum MSP1 vaccine, P30P2MSP1-19 as a model immunogen. The adjuvants showed preferential requirements for the immune mediators to induce immune responses to MSP1-19, and the effects were formulation-specific. While emulsion-type adjuvants were highly effective in mice, their potency was more readily suppressed by immune knockouts; and additions of immunomodulators were required to restore efficacy. Formulated adjuvants had characteristics distinct from their individual components, and multi-components formulations were not necessarily superior. We conclude that perturbation of immune environments will have measurable impact on adjuvants' potency. Evaluation of adjuvants in immune knockout models may be a supplementary approach to measure and compare adjuvants' efficacy, and to further unveil their distinct biological activities.

Oral vaccination: where we are?

As early as 900 years ago, the Bedouins of the Negev desert were reported to kill a rabid dog, roast its liver and feed it to a dog-bitten person for three to five days according to the size and number of bites [1] . In sixteenth century China, physicians routinely prescribed pills made from the fleas collected from sick cows, which purportedly prevented smallpox. One may dismiss the wisdom of the Bedouins or Chinese but the Nobel laureate, Charles Richet, demonstrated in 1900 that feeding raw meat can cure tuberculous dogs - an approach he termed zomotherapy. Despite historical clues indicating the feasibility of oral vaccination, this particular field is notoriously infamous for the abundance of dead-end leads. Today, most commercial vaccines are delivered by injection, which has the principal limitation that recipients do not like needles. In the last few years, there has been a sharp increase in interest in needle-free vaccine delivery; new data emerges almost daily in the literature. So far, there are very few licensed oral vaccines, but many more vaccine candidates are in development. Vaccines delivered orally have the potential to take immunization to a fundamentally new level. In this review, the authors summarize the recent progress in the area of oral vaccines.

Delivery systems and adjuvants for oral vaccines

The oral route is the ideal means of delivering prophylactic and therapeutic vaccines, offering significant advantages over systemic delivery. Most notably, oral delivery is associated with simple administration and improved safety. In addition, unlike systemic immunisation, oral delivery can induce mucosal immune responses. However, the oral route of vaccine delivery is the most difficult because of the numerous barriers posed by the gastrointestinal tract. To facilitate effective immunisation with peptide and protein vaccines, antigens must be protected, uptake enhanced and the innate immune response activated. Numerous delivery systems and adjuvants have been evaluated for oral vaccine delivery, including live vectors, inert particles and bacterial toxins. Although developments in oral vaccines have been disappointing so far, in terms of the generation of products, the availability of a range of novel delivery systems offers much greater hope for the future development of improved oral vaccines.

The role of adjuvants in the development of mucosal vaccines

It is well-established that most pathogens that cause infectious diseases enter the host via mucosal membranes of the respiratory, digestive and genital tracts. Some parenterally administered vaccines induce protection against mucosal pathogens. However, there is increasing evidence that mucosal protection is better afforded by mucosal vaccination, particularly for the induction of memory responses. Mucosal vaccines must pass several difficult hurdles before entering the host and inducing an effective and protective immune response. This review deals with present and past efforts in devising effective mucosal vaccines using delivery systems and immunopotentiating adjuvants for protein-based vaccines. The paper will conclude with the authors' opinion on how the field will or should progress in the future and what will be the required components of ideal future mucosal vaccines that can induce immunological memory.

Characterisation of the oral adjuvant effect of lemnan, a pectic polysaccharide of Lemna minor L

Lemnan LM, apiogalacturonanic pectin of duckweed Lemna minor L. was tested for adjuvant properties following oral administration with protein antigen. Male Swiss mice were orally immunized thrice with weekly intervals with free OVA or OVA with lemnan (LM). Lemnan LM was shown to increase delayed type hypersensitivity (DTH) and serum anti OVA IgG responses. LM was established to increase levels of both serum IgG1 and IgG2a subclasses, intestinal IgA and failed to elevate levels of serum IgE. Lemnan was found to increase the adhesion of macrophages and to enhance the generation of oxygen radicals by macrophages in response to phorbol 12-myristate 13-acetate. Serum OVA levels were four-fold higher in mice immunized with the mixture of OVA and LM in comparison with those in mice immunized with OVA only. Thus, substantial systemic and local mucosal immune responses were attained by oral immunization with the mixture of OVA and lemnan. Lemnan appeared to elicit adjuvant activity via induction of both Th1- and Th2-type responses. The immunopotentiating effect of lemnan may result from enhanced antigen ingestion and stimulation of macrophage activity.

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.

Crude saponins improve the immune response to an oral plant-made measles vaccine

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.

Enhanced immunity and protective efficacy against SIVmac251 intrarectal challenge following ad-SIV priming by multiple mucosal routes and gp120 boosting in MPL-SE

Previously, 39% of rhesus macaques primed orally, intranasally, and intratracheally with adenovirus (Ad)-simian immunodeficiency virus (SIV) recombinants and boosted with gp120 in monophosphoryl lipid A-stable emulsion (MPL-SE) remained aviremic or cleared or controlled viremia at the threshold of detection following SIV(mac251) intrarectal challenge (Study B). In contrast, no macaques primed orally and intranasally with Ad-SIV recombinants and boosted with gp120 in Quillaja Saponaria-21 exhibited undetectable viremia post-challenge (Study A). We conducted a detailed comparison of the studies to elucidate the effect of different vaccine regimens on induced immunity associated with the different challenge outcomes. Quantitative viral load comparisons were statistically analyzed. All immune responses were assessed at identical timepoints post-immunization, and cellular immunity was re-evaluated on cryopreserved cells from Study B macaques to match Study A data acquired with frozen cells. Study B exhibited greater protective efficacy, increased levels of p11C and p54m tetramer positive cells and a trend toward enhanced interferon-gamma secreting cells in response to Env and Gag peptides, modestly enhanced serum neutralizing antibodies, and greater positivity in anti-gp120 rectal IgA and IgG antibodies. Study A macaques exhibited greater positivity in salivary IgA anti-gp120 antibodies. Thus, the vaccine regimen using oral-intranasal-intratracheal priming and protein boosting in MPL-SE was superior, eliciting greater protective efficacy against pathogenic SIV(mac251) and enhanced SIV-specific immunity, systemically and at rectal sites. The mechanism(s) by which binding antibodies, lacking neutralizing activity against the primary challenge virus, may contribute to protection requires further study.

Modulation of Murine Host Response to Enteric Reovirus Infection by the Trichothecene Deoxynivalenol

Based on the known capacity of deoxynivalenol (DON) to target gut lymphoid tissue and IgA production, it was hypothesized that this mycotoxin interferes with the immune response to enteric reovirus infection. When mice were orally gavaged, first with 25 mg/kg bw DON, and then with reovirus serotype 1, strain Lang (T1/L) 2 or 12 h later, viral titers in the GI tract were 10-fold higher than control mice after 5 days. Virus was almost completely cleared in both treatment and control groups from intestinal tissue after 10 days. Real-time PCR indicated that, in infected control mice, reovirus lambda2 core spike (L2 gene) RNA per g feces in infected mice that were pretreated with DON was significantly higher at 1, 3, and 5 days than in infected mice only. In reovirus-infected mice, DON at doses of 10 and 25 mg/kg bw but not 2 and 5 mg/kg bw increased fecal L2 RNA, whereas DON doses as low as 2 mg/kg potentiated L2 RNA levels in Peyer's patches (PP). Reovirus-specific IgA levels in feces of mice treated with DON were significantly elevated, as were specific IgA responses in lamina propria and PP fragment cultures. Similar effects were observed for serum IgA and IgG. DON suppressed IFN-gamma responses in PP to reovirus at 3 and 5 days as compared to infected controls, while IL-2 mRNA concentrations were unaffected. Although reovirus alone did not induce Th2 cytokine mRNAs in PP, DON exposure significantly elevated IL-4, IL-6, and IL-10 mRNA expression at various times during the infection. ELISPOT revealed that mRNA expression data corresponded to suppression of IFN-gamma- and enhancement of IL-4-producing cell responses in PP cultures from DON-treated mice. Taken together, these data suggest that DON transiently increased both severity of the reovirus infection and shedding in feces as well as elevated reovirus IgA responses. These effects corresponded to suppressed Th1 and enhanced Th2 cytokine expression.

Mucosal adjuvants and delivery systems for protein-, DNA- and RNA-based vaccines

Almost all vaccinations today are delivered through parenteral routes. Mucosal vaccination offers several benefits over parenteral routes of vaccination, including ease of administration, the possibility of self-administration, elimination of the chance of injection with infected needles, and induction of mucosal as well as systemic immunity. However, mucosal vaccines have to overcome several formidable barriers in the form of significant dilution and dispersion; competition with a myriad of various live replicating bacteria, viruses, inert food and dust particles; enzymatic degradation; and low pH before reaching the target immune cells. It has long been known that vaccination through mucosal membranes requires potent adjuvants to enhance immunogenicity, as well as delivery systems to decrease the rate of dilution and degradation and to target the vaccine to the site of immune function. This review is a summary of current approaches to mucosal vaccination, and it primarily focuses on adjuvants as immunopotentiators and vaccine delivery systems for mucosal vaccines based on protein, DNA or RNA. In this context, we define adjuvants as protein or oligonucleotides with immunopotentiating properties co-administered with pathogen-derived antigens, and vaccine delivery systems as chemical formulations that are more inert and have less immunomodulatory effects than adjuvants, and that protect and deliver the vaccine through the site of administration. Although vaccines can be quite diverse in their composition, including inactivated virus, virus-like particles and inactivated bacteria (which are inert), protein-like vaccines, and non-replicating viral vectors such as poxvirus and adenovirus (which can serve as DNA delivery systems), this review will focus primarily on recombinant protein antigens, plasmid DNA, and alphavirus-based replicon RNA vaccines and delivery systems. This review is not an exhaustive list of all available protein, DNA and RNA vaccines, with related adjuvants and delivery systems, but rather is an attempt to highlight many of the currently available approaches in immunopotentiation of mucosal vaccines.

Study of the viral infections and cytokines associated with recurrent aphthous ulceration

Mouth ulcers are one of the most common oral complaints. However, the association between oral ulceration and viruses and cytokines is uncertain. We detected the presence of human papilloma virus (HPV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV)-1, HSV-2 and human herpesvirus (HHV)-8 DNA in oral tissues by polymerase chain reaction (PCR) and Southern hybridization techniques, and quantified the serum levels of cytokines including interleukin (IL)-2, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), soluble Fas (sFas) and the Fas ligand (FasL) by enzyme-linked immunosorbent assay (ELISA) for 67 recurrent aphthous ulcer (RAU) patients and 72 normal individuals. Seven patient specimens were excluded from the study due to the negative PCR results for the beta-globin used as the internal control. Among the 32 (53.3%) virus-positive results from 60 patients' samples, 8 (13.3%) HPV, 4 (6.7%) HSV-1, 11 (18.3%) CMV, 9 (15.0%) EBV, and 16 (26.7%) HHV-8 samples proved to be positive. No HSV-2-positive samples were found. The percentage of single-virus infection (56.3%) was significantly greater than that of double-virus co-infection (31.3%) and the percentage of double-virus co-infection was significantly greater than the percentage of triple-virus co-infection (12.5%) (P < 0.05). In the 72 normal oral-tissue specimens, no viral DNA was detected. The mean serum cytokine level for patients was significantly (P < 0.05) greater than for controls for most of the separate age groups. The mean serum cytokine concentrations for the patient group demonstrated a diffuse pattern covering a wide range of serum concentrations, a very different result from the compact serum concentration pattern and lower mean serum cytokine concentrations revealed by the normal group. Overall association between viruses and recurrent aphthous ulceration is HHV-8 > CMV > EBV > HPV > HSV-1, regarding the frequency of prevalence (P < 0.05).

Application of Quillaja saponaria extracts as oral adjuvants for plant-made vaccines

Extracts from the Quillaja saponaria tree are known to provide immune potentiating responses and, hence, can be useful as adjuvants. Partial purification from the crude (food-grade) extract results in Quil A, which is contained in several veterinary vaccines. Further purification can provide concentrated saponin fractions such as QS-21, which is currently under investigation as a potential adjuvant for use in humans. Purified saponins have proven safe and effective when injected and have significantly enhanced the efficacy of some oral vaccines under clinical investigation. Toxicity of the food-grade extract from Quillaja saponaria has limited its use as a parenteral adjuvant; however, this toxicity seems to be abated when delivered orally. It is commonly used within the food and beverage industries and has no documented toxicity in humans at the present levels of consumption. Use of transgenic plants has been proposed as an alternative system for oral vaccine production and administration, and it is likely that an oral adjuvant will be required in most cases. Food-grade saponins have significant advantages for use with plant-made vaccines and are likely to provide a broad adjuvant effect due to the multiple saponin components. A review of the origin, production, biological activity, toxicity and use in the food industry is provided for Quillaja saponaria extract. Previous evaluation of this adjuvant in preclinical studies with plant made vaccines is discussed and a proposed level of experimental use in humans is provided.

Panax ginseng induces production of proinflammatory cytokines via toll-like receptor

Ginseng radix, the dried root of Panax ginseng C. A. Meyer, has been shown to enhance the ability to resist microbial infections. Proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, and interferon-gamma (IFN-gamma) are produced by macrophages treated with ginseng radix extract (GRE) in vitro as well as in vivo. However, the molecular mechanisms of the production are still not clear. In the present study, we demonstrated that production of TNF-alpha and IFN-gamma was induced by GRE in spleen cells and peritoneal macrophages from C3H/HeN mice but was impaired in C3H/HeJ mice carrying a defective toll-like receptor-4 (TLR-4) gene. In addition to these cytokines, the expression of IFN-beta and inducible nitric oxide synthase (iNOS) mRNAs was also increased in GRE-treated C3H/HeN spleen cells. We investigated the possibility that GRE contains a lipopolysaccharide (LPS)-like component. However, GRE induced production of TNF-alpha and IFN-gamma in the presence of polymyxin B, an LPS inhibitor. Furthermore, a Limulus amebocyte lysate assay showed that the endotoxin content of GRE was below the threshold level of 1 ng/ml LPS. These results suggest that GRE contains a non-LPS agent that enhances innate immunity through production of proinflammatory cytokines via TLR-4.

Role of interleukin-4 (IL-4) and IL-10 in serum immunoglobulin G antibody responses following mucosal or systemic reovirus infection

Mucosal and parenteral immunizations elicit qualitatively distinct immune responses, and there is evidence that mucosal immunization can skew the balance of T helper 1 and T helper 2 responses. However, a clear picture of the effect of the route of infection on the balance of the T helper responses has not yet emerged. Our laboratory previously demonstrated that oral reovirus infection elicits specific serum immunoglobulin G2a (IgG2a), while parenteral reovirus infection elicits the mixed production of specific serum IgG2a and IgG1 in mice of the H-2(d) haplotype. Knowing that IgG2a production is indicative of a T helper 1 response and IgG1 production is indicative of a T helper 2 response, we hypothesized that the route of infection influences the development of T helper 1 and T helper 2 responses. Using quantitative reverse transcription-PCR, we found that mRNA for the T helper 1 cytokines gamma interferon and interleukin-12 (IL-12) were expressed in draining lymphoid tissues following both oral and parenteral infections. However, we observed that mRNA for the T helper 2 cytokine IL-10 was suppressed in the Peyer's patches and mesenteric lymph nodes and IL-4 mRNA was suppressed in the mesenteric lymph nodes compared to noninfected controls, following oral infection. Using recombinant cytokines and cytokine knockout mice, we confirmed that IL-4 plays a major role in mediating the route-of-infection-dependent differences in serum IgG subclass responses. Therefore, the route of infection needs to be taken into consideration when developing vaccines and adjuvant therapies.

New generation of mucosal adjuvants for the induction of protective immunity

Invasion of infectious agents through mucosal surfaces can be prevented by use of the common mucosal immune system (CMIS), which interconnects inductive tissues, including Peyer's patches (PPs) and nasopharyngeal-associated lymphoreticular tissue (NALT), and effector tissues of the intestinal and respiratory tracts. In order for the CMIS to induce maximal protective mucosal immunity, co-administration of mucosal adjuvant has been shown to be essential. When vaccine antigen is administered together with mucosal adjuvant, antigen-specific T-helper (Th) 1 and Th2 cells, cytotoxic T lymphocytes (CTLs) and IgA B cell responses are effectively induced by oral or nasal routes via the CMIS. In the early stages of induction of mucosal immune response, the uptake of orally or nasally administered antigens is achieved through a unique set of antigen-sampling cells, M cells located in follicle-associated epithelium (FAE) of inductive sites. After successful uptake, the antigens are immediately processed and presented by the underlying dendritic cells (DCs). Elucidation of the molecular/cellular characteristics of M cells and mucosal DCs will greatly facilitate the design of a new generation of effective mucosal adjuvants and of a vaccine delivery vehicle that maximises the use of the CMIS. Our recent efforts at mucosal vaccine development have focused on nasal administration of vaccine antigen together with nontoxic mutant-based or cytokine-/chemokine-based adjuvant for the induction of the protective immunity. To this end, a chimeric form of a nontoxic adjuvant combining the merits of mutant cholera toxin A subunit (mCT-A) and heat labile toxin B subunit (LT-B) was created as the second generation of detoxified toxin-based mucosal adjuvant. When a vaccine antigen was coexpressed together with an immune stimulatory/delivery molecule in crop seed, this edible vaccine is not only effective but also extremely practical in that it can be produced in huge quantities and preserved and shipped over long distances at room temperature without altering the quality of the vaccine. Because such qualities would greatly facilitate global vaccination, this new generation edible vaccines with a built-in adjuvant and/or M cell-targeted edible vaccine promises to be a powerful weapon for combating infectious diseases and bioterrorism.

Epidermal powder immunization of mice and monkeys with an influenza vaccine

Epidermal powder immunization (EPI) with an influenza vaccine and an adjuvant such as QS-21, LTR72, or cholera toxin elicited augmented serum and mucosal antibody responses in mice. Rhesus macaques, which have an immune system and skin structure similar to humans, were used to further evaluate the immunogenicity of the influenza vaccine following EPI. EPI of rhesus macaques with an influenza vaccine and QS-21 adjuvant elicited significantly higher serum hemagglutination inhibition (HI) titers than antigen alone administered by EPI or by intramuscular (IM) injection using a needle and syringe. In the absence of QS-21, EPI and IM injection elicited comparable HI titers in the monkeys. This study suggests that EPI is a promising technique for administering human vaccine and that QS-21 augments the immunogenicity of co-administered influenza vaccine.

Effective mucosal immunity to anthrax: neutralizing antibodies and Th cell responses following nasal immunization with protective antigen

Mucosal, but not parenteral, immunization induces immune responses in both systemic and secretory immune compartments. Thus, despite the reports that Abs to the protective Ag of anthrax (PA) have both anti-toxin and anti-spore activities, a vaccine administered parenterally, such as the aluminum-adsorbed anthrax vaccine, will most likely not induce the needed mucosal immunity to efficiently protect the initial site of infection with inhaled anthrax spores. We therefore took a nasal anthrax vaccine approach to attempt to induce protective immunity both at mucosal surfaces and in the peripheral immune compartment. Mice nasally immunized with recombinant PA (rPA) and cholera toxin (CT) as mucosal adjuvant developed high plasma PA-specific IgG Ab responses. Plasma IgA Abs as well as secretory IgA anti-PA Abs in saliva, nasal washes, and fecal extracts were also induced when a higher dose of rPA was used. The anti-PA IgG subclass responses to nasal rPA plus CT consisted of IgG1 and IgG2b Abs. A more balanced profile of IgG subclasses with IgG1, IgG2a, and IgG2b Abs was seen when rPA was given with a CpG oligodeoxynucleotide as adjuvant, suggesting a role for the adjuvants in the nasal rPA-induced immunity. The PA-specific CD4(+) T cells from mice nasally immunized with rPA and CT as adjuvant secreted low levels of CD4(+) Th1-type cytokines in vitro, but exhibited elevated IL-4, IL-5, IL-6, and IL-10 responses. The functional significance of the anti-PA Ab responses was established in an in vitro macrophage toxicity assay in which both plasma and mucosal secretions neutralized the lethal effects of Bacillus anthracis toxin.

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QS-21 structure/function studies: effect of acylation on adjuvant activity

QS-21 is a natural saponin adjuvant derived from the tree Quillaja saponaria Molina. Previous studies over a limited dose range suggested the acylation is critical to adjuvant activity. In this study, we prepared DS-1 (deacylated QS-21) and RDS-1 (reacylated DS-1 with dodecylamine at a different site than QS-21) to determine the effect on a dose-response curve over a wider range in mice. DS-1 and RDS-1 induced IgG1 responses at higher doses compared to that induced by QS-21. DS-1 was inactive for inducing IgG2a or CTL responses at any doses. RDS-1 showed moderate IgG2a response at 240 microg, but did not show CTL response at any dose evaluated.

Synthetic biomimetic supra molecular Biovector (SMBV) particles for nasal vaccine delivery

For the optimal delivery of antigens to mucosal tissues, especially as nasal sprays, protein antigen alone is often not sufficient. A clear need for nasal delivery systems has therefore evolved, especially for Influenza A vaccines. Such technologies will be even more essential for new modern vaccines based on recombinant antigens. Here we describe synthetic biomimetic supra molecular Biovector (SMBV) which have proven in preclinical and clinical evaluation to be suitable candidates for the delivery of nasal vaccines. They also demonstrate the potential to work with multiple antigens and furthermore allow combination with adjuvants. These Biovectors can associate with internal or lipid layer membrane proteins and peptides due to their charged polysaccharide core. The mimicry with viruses is also provided through their size of 60-80 nm, which allows sterilization by filtration. This makes them an ideal tool for the development of modern nasal vaccines, as they have shown to be able to induce the desired types of humoral immunity (serosal and mucosal immunity, IgA and IgG antibodies) as well as cellular immunity (CD4 and CD8 responses).