Emulsion Adjuvant Research Articles

Phytochemical Constituents of Propolis Flavonoid, Immunological Enhancement, and Anti-porcine Parvovirus Activities Isolated From Propolis

Propolis is widely used in health preservation and disease healing; it contains many ingredients. The previous study had revealed that the ethanolic or water extracts of propolis have a wide range of efficacy, such as antiviral, immune enhancement, anti-inflammatory, and so on, but its antiviral components and underlying mechanism of action remain unknown. In this study, we investigated the chemical composition, anti-porcine parvovirus (PPV) effectiveness, and immunological enhancement of propolis flavone ethanolic extracts. The chemical composition of propolis flavone was distinguished by ultra-performance liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry analysis. In this study, the presence and characterization of 26 major components were distinguished in negative ionization modes to evaluate the effects of propolis flavonoid used as an adjuvant on the immune response of Landrace–Yorkshire hybrid sows immunized with an inactivated vaccine of PPV. Thirty Landrace-Yorkshire hybrid sows were randomly assigned to one of three groups, and the sows in the adjuvant groups were intramuscularly injected with PPV vaccine with a 2.0-ml propolis flavonoid adjuvant (PA) and oil emulsion adjuvant. After that, serum hemagglutination inhibition antibody titers and specific immunoglobulin (Ig)M and IgG subclasses were measured to evaluate the adjuvant effects of propolis flavonoid on the humoral immune responses, as well as peripheral lymphocyte proliferation activity and serum concentrations of Th1 and Th2 cytokines for cellular immunity. Results indicated an enhancing effect of PA on IgM, interleukins 2 and 4, interferon-γ, and IgG subclass responses. Especially in the effect of improving cellular immune response, the PA was the best. These findings suggested that PA can significantly enhance the immune responses against the PPV vaccine and could be an alternative way to improve PPV vaccination in sows. Furthermore, we screened the PF chemical components to the effectiveness of anti-PPV. Ferulic acid has an excellent anti-PPV effect.

Ectopic Lymphoid Follicle Formation and Human Seasonal Influenza Vaccination Responses Recapitulated in an Organ-on-a-Chip.

Lymphoid follicles (LFs) are responsible for generation of adaptive immune responses in secondary lymphoid organs and form ectopically during chronic inflammation. A human model of ectopic LF formation will provide a tool to understand LF development and an alternative to non‐human primates for preclinical evaluation of vaccines. Here, it is shown that primary human blood B‐ and T‐lymphocytes autonomously assemble into ectopic LFs when cultured in a 3D extracellular matrix gel within one channel of a two‐channel organ‐on‐a‐chip microfluidic device. Superfusion via a parallel channel separated by a microporous membrane is required for LF formation and prevents lymphocyte autoactivation. These germinal center‐like LFs contain B cells expressing Activation‐Induced Cytidine Deaminase and exhibit plasma cell differentiation upon activation. To explore their utility for seasonal vaccine testing, autologous monocyte‐derived dendritic cells are integrated into LF Chips. The human LF chips demonstrate improved antibody responses to split virion influenza vaccination compared to 2D cultures, which are enhanced by a squalene‐in‐water emulsion adjuvant, and this is accompanied by increases in LF size and number. When inoculated with commercial influenza vaccine, plasma cell formation and production of anti‐hemagglutinin IgG are observed, as well as secretion of cytokines similar to vaccinated humans over clinically relevant timescales.

Immunogenicity of an inactivated novel goose parvovirus vaccine for short beak and dwarfism syndrome in Cherry Valley ducks.

Duck short beak and dwarfism syndrome (SBDS) is a viral infectious disease caused by novel goose parvovirus (NGPV), which has been responsible for serious economic losses to the Chinese duck industry in recent years. Currently, there is no effective vaccine against this disease. In this study, we developed an inactivated virus vaccine candidate for SBDS based on NGPV strain DS15 isolated from a duck in China. Immune efficacy was evaluated in 112 ducks, which were randomly divided into vaccination, challenge-control, vaccination-challenge, and blank control groups (28 per group). Clinical characteristics, antibodies, virus excretion, viremia, and pathological changes were monitored. No morbidity or death was observed in the immunized ducks, which showed normal weight and a good mental state. High levels of serum antibodies (optical density at 450nm of ~0.63) were detected in ducks immunized with the inactivated vaccine at 7days post-vaccination (dpv), and the titer of virus-neutralizing antibodies increased from 1:23 to 1:28.5 from 7 to 42dpv. Measurement of the viral load in anal swab, serum, and tissue samples showed that vaccination significantly inhibited the replication of NGPV in immunized ducks. Moreover, NGPV could not be isolated from the spleens of immunized or vaccinated and challenged ducks. Collectively, these results demonstrate that the newly developed inactivated NGPV vaccine, administered in an oil emulsion adjuvant, possesses good immunogenicity and represents a potentially powerful tool for SBDS prevention and control.

A solid-in-oil-in-water emulsion: An adjuvant-based immune-carrier enhances vaccine effect

The biomaterial-based immunoengineering has become one of the most attractive research fields in the last decade. In the present study, a solid-in-oil-in-water (S/O/W) emulsion encapsulating antigen in the oil phase of an oil-in-water (O/W) emulsion was prepared as a novel vaccine carrier consisting of similar materials to the emulsion adjuvant of which the safety, immunogenicity and vaccination efficacy have been already confirmed in human. Direct observation by high-resolution confocal laser scanning microscopy and small angle X-ray scattering analysis showed that the antigens were dispersed inside of the oil phase of the S/O/W emulsion as solid-state particles. The S/O/W emulsion robustly produced antigen-specific antibodies and enhanced the antitumor effects in a therapeutic cancer vaccination compared with free antigens or the O/W emulsion in vivo. This result is in good agreement with the activation effect of antigen-specific cytotoxic T lymphocytes and antigen presentation by the S/O/W emulsion, indicating that the S/O/W emulsion consisting of already approved materials is a promising vaccine carrier to produce both humoral and cellular immunity.

Optimising the oil phases of aluminium hydrogel-stabilised emulsions for stable, safe and efficient vaccine adjuvant.

To increase antibody secretion and dose sparing, squalene-in-water aluminium hydrogel (alum)-stabilised emulsions (ASEs) have been developed, which offer increased surface areas and cellular interactions for higher antigen loading and enhanced immune responses. Nevertheless, the squalene (oil) in previous attempts suffered from limited oxidation resistance, thus, safety and stability were compromised. From a clinical translational perspective, it is imperative to screen the optimal oils for enhanced emulsion adjuvants. Here, because of the varying oleic to linoleic acid ratio, soybean oil, peanut oil, and olive oil were utilised as oil phases in the preparation of aluminium hydrogel-stabilised squalene-in-water emulsions, which were then screened for their stability and immunogenicity. Additionally, the underlying mechanisms of oil phases and emulsion stability were unravelled, which showed that a higher oleic to linoleic acid ratio increased anti-oxidative capabilities but reduced the long-term storage stability owing to the relatively low zeta potential of the prepared droplets. As a result, compared with squalene-in-water ASEs, soybean-in-water ASEs exhibited comparable immune responses and enhanced stability. By optimising the oil phase of the emulsion adjuvants, this work may offer an alternative strategy for safe, stable, and effective emulsion adjuvants.Electronic Supplementary MaterialSupplementary material is available in the online version of this article at 10.1007/s11705-021-2123-1 and is accessible for authorized users.

Emulsion Adjuvants for Use in Veterinary Vaccines.

The use of emulsion as adjuvants is widely used in veterinary vaccines. Emulsion adjuvants are inexpensive, stable, and relatively easy to prepare into vaccine formulations. Here we describe the preparation of oil-in-water emulsion adjuvant that has been shown to enhance immune responses and protect against diseases in pigs. This emulsion adjuvant and its variations could potentially be used alone or in combination with other adjuvants in veterinary vaccine formulations.

CAvant® WO-60 as an Effective Immunological Adjuvant for Avian Influenza and Newcastle Disease Vaccine.

Despite the immunogenicity of vaccines currently used in poultry, several pathogens, including avian influenza virus (AIV) and Newcastle disease virus (NDV), cause enormous economic losses to the global poultry industry. The efficacy of vaccines can be improved by the introduction of effective adjuvants. This study evaluated a novel water-in-oil emulsion adjuvant, CAvant® WO-60, which effectively enhanced both the immunogenicity of conserved influenza antigen sM2HA2 and inactivated whole H9N2 antigen (iH9N2). CAvant® WO-60 induced both humoral and cell-mediated immunity in mice and provided 100% protection from challenge with 10 LD50 of A/Aquatic bird/Korea/W81/2005 (H5N2) and A/Chicken/Korea/116/2004 (H9N2) AIV. Importantly, immunization of chickens with iH9N2 plus inactivated NDV LaSota (iNDV) bivalent inactivated vaccine emulsified in CAvant® WO-60 induced seroprotective levels of antigen-specific antibody responses. Taken together, these results suggested that CAvant® WO-60 is a promising adjuvant for poultry vaccines.

Single-vial filovirus glycoprotein vaccines: Biophysical characteristics and immunogenicity after co-lyophilization with adjuvant

Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV), and Marburg marburgvirus (MARV) are the most prevalent and pathogenic species of filovirus. Previously, we showed that glycoprotein antigens from each virus could be lyophilized to create thermostable monovalent subunit vaccines. However, cross-protection is not expected from the monovalent vaccines and therefore developing a trivalent filovirus vaccine would be desirable. Subunit protein vaccines often require the addition of an adjuvant to sufficiently boost the immunogenicity. Typically, liquid suspensions or emulsions of adjuvants and lyophilized antigens are stored in separate vials to avoid destabilizing interactions and are only mixed immediately before administration. Herein, we describe the development and characterization of monovalent and trivalent filovirus vaccines that are co-lyophilized with a squalane-in-water emulsion adjuvant. We found that the single-vial presentation retained adjuvant particle diameter and zeta potential after lyophilization and reconstitution. Furthermore, the trivalent vaccines elicited high antibody levels against all three antigens in mice and non-human primates. These results advance the prospect of developing a single-vial trivalent filovirus vaccine, which would enable easier distribution and administration of the vaccine to resource-poor areas.

Natural killer cells contribute to enhanced respiratory disease after oil-in-water emulsion adjuvanted vaccination against respiratory syncytial virus and infection

ABSTRACT Respiratory syncytial virus (RSV) infection caused severe acute respiratory disease in children and the elderly. There is no licensed vaccine. It has been a challenging problem to avoid vaccine enhanced respiratory disease in developing a safe and effective RSV vaccine. Here, we investigated the impact of MF59-like oil-in-water emulsion adjuvant Addavax on the vaccine efficacy of inactivated split RSV (sRSV) and the roles of natural killer (NK) cells in enhanced respiratory disease in sRSV vaccinated mice after RSV infection. Addavax-adjuvanted sRSV vaccination induced higher levels of IgG1 isotype antibodies and more effective lung viral clearance upon RSV infection but promoted enhanced respiratory disease of weight loss, pulmonary inflammation, and NK and NK T (NKT) cell infiltrations in the lungs. Antibody treatment depleting NK cells prior to RSV infection resulted in preventing severe weight loss and histopathology, as well as attenuating infiltration of dendritic cell subsets and TNF-α+ T cells in the lungs. This study demonstrated the impacts of oil-in-water emulsion adjuvant on sRSV vaccination and the potential roles of NK and NKT cells in protection and respiratory disease after adjuvanted RSV vaccination and infection in a mouse model.

Squalene-Based Influenza Vaccine Adjuvants and Their Impact on the Hemagglutinin-Specific B Cell Response.

Influenza infections continue to cause significant annual morbidity and mortality despite ongoing influenza vaccine research. Adjuvants are administered in conjunction with influenza vaccines to enhance the immune response and strengthen protection against disease. Squalene-based emulsion adjuvants including MF59, AS03, and AF03, are registered for administration with influenza vaccines and are widely used in many countries. Squalene-based emulsion adjuvants induce a strong innate immune response, enhancing antigen presentation both quantitively and qualitatively to generate strong B cell responses and antibody production. They also diversify the reactivity profiles and strengthen the affinities of antibodies against the influenza hemagglutinin, increasing protection across virus clades. In this review, we consider the mechanisms of the enhancement of innate and adaptive immune responses by squalene-based emulsionSE adjuvants and the resulting increase in magnitude and breadth of hemagglutinin-specific B cell responses. We relate observed effects of SE adjuvants and current mechanistic understandings to events in responding lymph nodes. These insights will guide the rational design and optimization of influenza vaccines to provide broad and effective protection.

Prophylactic efficacy against Mycobacterium tuberculosis using ID93 and lipid-based adjuvant formulations in the mouse model.

An estimated 10 million people developed tuberculosis (TB) disease in 2019 which underscores the need for a vaccine that prevents disease and reduces transmission. The aim of our current studies is to characterize and test a prophylactic tuberculosis vaccine comprised of ID93, a polyprotein fusion antigen, and a liposomal formulation [including a synthetic TLR4 agonist (glucopyranosyl lipid adjuvant, GLA) and QS-21] in a preclinical mouse model of TB disease. Comparisons of the ID93+GLA-LSQ vaccines are also made to the highly characterized ID93+GLA-SE oil-in-water emulsion adjuvant, which are also included these studies. The recent success of vaccine candidate M72 combined with adjuvant AS01E (GlaxoSmithKline Biologicals) in reducing progression to active disease is promising and has renewed excitement for experimental vaccines currently in the TB vaccine pipeline. The AS01E adjuvant contains monophosphoryl lipid A (MPL) and QS-21 (a saponin) in a liposomal formulation. While AS01E has demonstrated potent adjuvant activity as a component of both approved and experimental vaccines, developing alternatives to this adjuvant system will become important to fill the high demand envisioned for future vaccine needs. Furthermore, replacement sources of potent adjuvants will help to supply the demand of a TB vaccine [almost one-quarter of the world’s population are estimated to have latent Mycobacterium tuberculosis (Mtb) according to the WHO 2019 global TB report], addressing (a) cost of goods, (b) supply of goods, and (c) improved efficacy of subunit vaccines against Mtb. We show that both ID93+GLA-SE (containing an emulsion adjuvant) and ID93+GLA-LSQ (containing a liposomal adjuvant) induce ID93-specific TH1 cellular immunity including CD4+CD44+ T cells expressing IFNγ, TNF, and IL-2 (using flow cytometry and intracellular cytokine staining) and vaccine-specific IgG2 antibody responses (using an ELISA). In addition, both ID93+GLA-SE and ID93+GLA-LSQ effectively decrease the bacterial load within the lungs of mice infected with Mtb. Formulations based on this liposomal adjuvant formulation may provide an alternative to AS01 adjuvant systems.

H7N9 pandemic preparedness: A large-scale production of a split inactivated vaccine

In March 2013 it was reported by the World Health Organization (WHO) the first cases of human infections with avian influenza virus A (H7N9). From 2013 to December 2019, 1568 cases have been reported with 616 deaths. H7N9 infection has been associated with high morbidity and mortality rates, and vaccination is currently the most effective way to prevent infections and consequently flu-related severe illness. Developing and producing vaccines against pandemic influenza viruses is the main strategy for a response to a possible pandemic. This study aims to present the production of three industrial lots under current Good Manufacturing Practices (cGMP) of the active antigen used to produce the pandemic influenza vaccine candidate against A(H7N9). These batches were characterized and evaluated for quality standards and tested for immunogenicity in mice. The average yield was 173.50 ± 7.88 μg/mL of hemagglutinin and all the preparations met all the required specifications. The formulated H7N9 vaccine is poorly immunogenic and needs to be adjuvanted with an oil in water emulsion adjuvant (IB160) to achieve a best immune response, in a prime and in a boost scheme. These data are important for initial production planning and preparedness in the case of a H7N9 pandemic.

Development and evaluation of a recombinant VP2 neutralizing epitope antigen vaccine candidate for infectious bursal disease virus.

Infectious bursal disease (IBD) is one of the most economically important infectious diseases. Currently, vaccination is the most effective method to prevent IBD. Medium-virulence vaccines can damage the bursa of Fabricius and result in immunosuppression. Therefore, it is essential to develop a safe and effective vaccine against infectious bursal disease virus (IBDV). In this study, the five neutralizing epitopes of the IBDV VP2 protein were confirmed by neutralizing single chain variable fragment antibodies. Then, the neutralizing epitopes antigen (NEA) protein was constructed with five neutralizing epitopes and expressed by pET-27b. Furthermore, the immune effect and protective immunity of the NEA protein with the following adjuvants were evaluated in specific-pathogen-free chickens: oil emulsion adjuvant (OEA), double emulsion adjuvant (DEA), granulocyte-macrophage colony-stimulating factor (GM-CSF) adjuvant and complete Freund's adjuvant (CFA). The experimental results demonstrated that chickens immunized with NEA vaccines elicited stronger humoral and/or cellular immune responses and inflammatory responses than those in the NEA protein group. Chickens were protected in OEA, CFA and GM-CSF adjuvant groups, which were challenged with virulent IBDV BC6/85. Furthermore, IBDV RNA was not measured, and there appeared to be little apoptosis in the bursa of Fabricius based on TUNEL histology and the expression of Bax and Bcl-2 in the OEA, CFA and GM-CSF adjuvant groups. Based on the experimental results, the advantages and disadvantages of adjuvants and industrial production methods, GM-CSF was found to be the optimal adjuvant. Therefore, NEA with GM-CSF adjuvant is a promising vaccine candidate against IBDV, and it provides a framework for developing other vaccines against infectious viral diseases.

Recombinant AhpC antigen from Mycobacterium bovis boosts BCG-primed immunity in mice.

Tuberculosis (TB) is still one of the most common infectious diseases around the world despite the widespread use of BCG (bacille Calmette-Guerin) strain of Mycobacterium bovis as a vaccine. This vaccine does not always protect people from TB, and, thus, new effective vaccines or vaccination strategies are being investigated. In this study, alkyl hydroperoxide reductase (AhpC) from M. bovis was evaluated as a new candidate vaccine antigen against TB in BALB/c mice model. The ahpC gene was amplified from M.bovis genome, cloned, and expressed in Escherichia coli. Vaccine antigen AhpC was formulated with Montanide ISA 61 VG, an oil-based emulsion adjuvant. Both IgG and IL-12 responses were observed in mice after administering the formulation both as a subunit vaccine alone and also as a booster vaccine for BCG immunization. However, a long-lasting response was observed when AhpC formulation was used as a booster (for BCG-primed immunization) as compared to being used as a subunit vaccine alone. In short, these findings suggested that AhpC has the potential to be used as a booster vaccine candidate for BCG-primed immunization.

Preparation and application of oil emulsion adjuvant of animal vaccines containing flavonoid saponins

With the development of immunology, the application of vaccines plays an important role in controlling the epidemic of animal diseases, and the development of adjuvants is particularly important. Immune adjuvant is a kind of non-specific immune enhancer. It can effectively induce long-term and high-efficiency specific immune response and improve the self-protection ability of the body when injected with antigen or in advance. In this paper, a flavonoid saponin extracted from persimmon leaves was added on the basis of traditional oil adjuvant. The animal potency test showed that the oil emulsion adjuvant containing flavonoid saponin was more effective than single use, and could be widely used in the development of animal vaccine.

A potent novel vaccine adjuvant based on straight polyacrylate

A structure-activity study was conducted to identify the structural characteristics underlying the adjuvant activity of straight (i.e. non-crosslinked) polyacrylate polymers (PAAs) in order to select a new PAA adjuvant candidate for future clinical development. The study revealed that the adjuvant effect of PAA was mainly influenced by polymer size (Mw) and dose. Maximal effects were obtained with large PAAs above 350 kDa and doses above 100 μg in mice. Small PAAs below 10 kDa had virtually no adjuvant effect. HPSEC analysis revealed that PAA polydispersity index and ramification had less impact on adjuvanticity. Heat stability studies indicated that residual persulfate could be detrimental to PAA stability. Hence, this impurity was systematically eliminated by diafiltration along with small Mw PAAs and residual acrylic acid that could potentially affect product safety, potency and stability. The selected PAA, termed SPA09, displayed an adjuvant effect that was superior to that of a standard emulsion adjuvant when tested with CMV-gB in mice, even in the absence of binding to the antigen. The induced immune response was dominated by strong IFNγ, IgG2c and virus neutralizing titers. The activity of SPA09 was then confirmed on human cells via the innate immune module of the human MIMIC® system.

Preparedness against pandemic influenza: Production of an oil-in-water emulsion adjuvant in Brazil.

Increasing pandemic influenza vaccine manufacturing capacity is considered strategic by WHO. Adjuvant use is key in this strategy in order to spare the vaccine doses and by increasing immune protection. We describe here the production and stability studies of a squalene based oil-in-water emulsion, adjuvant IB160, and the immune response of the H7N9 vaccine combined with IB160. To qualify the production of IB160 we produced 10 consistency lots of IB160 and the average results were: pH 6.4±0.05; squalene 48.8±.0.03 mg/ml; osmolality 47.6±6.9 mmol/kg; Z-average 157±2 nm, with polydispersity index (PDI) of 0.085±0.024 and endotoxin levels <0.5 EU/mL. The emulsion particle size was stable for at least six months at 25°C and 24 months at 4–8°C. Two doses of H7N9 vaccine formulated at 7.5 μg/dose or 15 μg/dose with adjuvant IB160 showed a significant increase of hemagglutination inhibition (HAI) titers in sera of immunized BALB/c mice when compared to control sera from animals immunized with the H7N9 antigens without adjuvant. Thus the antigen-sparing capacity of IB160 can potentially increase the production of the H7N9 pandemic vaccine and represents an important achievement for preparedness against pandemic influenza and a successful North (IDRI) to South (Butantan Institute) technology transfer for the production of the adjuvant emulsion IB160.

Immunization with Bovine Serum Albumin (BSA) in Oil-Adjuvant Elicits IgM Antibody Response in Chinese Soft-Shelled Turtle (Pelodiscus Sinensis).

Immunoassays are among the frontline methods used for disease diagnosis and surveillance. Despite this, there are no immunoassays developed for the Chinese soft-shelled turtle (Pelodiscus sinensis), which has expanded into large scale commercial production in several Asian countries. One of the critical factors delaying the development of immunoassays is the lack of characterized soft-shelled turtle immunoglobulins. Herein, we used mass spectrometry together with the ProtQuest software to identify the soft-shelled turtle IgM heavy chain in serum, which again was used to produce a polyclonal anti-turtle-IgM in rabbits. Thereafter, the polyclonal anti-turtle-IgM was used as a secondary antibody in an indirect ELISA to evaluate antibody responses of soft-shelled turtles injected with the bovine serum albumin (BSA) model antigen. Our findings show that only turtle immunized with a water-in-oil BSA plus ISA 763A VG adjuvant (SEPPIC, France) emulsion had antibodies detected at 42 days post vaccination (dpv) while turtles injected with phosphate buffered saline (PBS) only as well as turtle injected with BSA dissolved in PBS had no significant antibody levels detected in serum throughout the study period. In summary, our findings show that rabbit polyclonal anti-turtle-IgM produced can be used in ELISA to measure serum antibody responses in immunized soft-shelled turtles. Future studies should explore its application in other immunoassays needed for the disease diagnosis and vaccine development for soft-shelled turtles.

Comparison of oil emulsion, mannosylated chitosan, and Bacillus vector adjuvants for vaccination against influenza in chickens

Summary Vaccination against influenza continues to be the primary method of control in many countries, but there is still a strong reliance on autogenous vaccines adjuvated with mineral oil emulsions known to induce overly high local inflammatory responses and lesions at the site of injection. The studies presented herein investigate various combinations of mannosylated chitosan adjuvant (MCA) and/or recombinant Bacillus construct adjuvant (BCA) containing highly conserved influenza antigens to assess their ability to function as an effective alternative adjuvant in influenza vaccination. In experiment 1, broilers were vaccinated via subcutaneous and/or drinking water application with an inactivated swine influenza in combination with MCA or commercial oil emulsion adjuvant. Subcutaneous or oral prime, followed by oral boost, resulted in the highest improvement in day 21 serum IgG hemagglutination inhibition (HI) titer, compared to the non-vaccinated control group. Experiment 2 tested BCA and MCA adjuvants, mixed with inactivated avian influenza virus in broilers. The group receiving combined subcutaneous and oral prime, followed by an oral boost containing both MCA and BCA adjuvants, exhibited significantly improved tracheal IgA HI titers. Experiment 3 investigated the ability of these adjuvated vaccines to protect against both homologous and heterologous highly pathogenic avian influenza challenge in layers. Groups receiving a subcutaneous prime followed by either subcutaneous or oral boost survived at 100%. Groups receiving only oral vaccine administrations did not exhibit improved survival. MCA and BCA adjuvants were found to improve immune responses in both broiler and layer-type chickens, equivalently matching immunogenicity and protection to the traditional mineral oil emulsion adjuvant. These studies suggest protective mucosal immunity can be achieved with vaccination strategies that incorporate MCA or BCA, but primary parenteral administration remains an important component of the vaccination strategy to achieve protective immunity.

Bovine immune response to leptospira antigen in different novel adjuvants and vaccine delivery platforms

Leptospirosis is a global zoonosis causing significant economic losses for cattle production. Current cattle vaccines against leptospirosis need improvement to provide efficacy against multiple serovars, reduce shedding in urine, and to induce earlier and more robust immune responses. In this study, Leptospira borgpetersenii serovar Hardjo strain 203 antigen was combined with novel adjuvants (a biodegradable polyanhydride compressed rod implant (VPEAR), poly(diaminosulfide) microparticles, a water-oil-water emulsion adjuvant, and aluminum hydroxide) to develop novel vaccines. Cattle were immunized twice, at a 4 week interval, with inoculums containing adjuvants alone or leptospira antigens and immune responses were compared to responses of cattle receiving a commercial monovalent leptospirosis vaccine (Spirovac). All animals were inoculated with a single dose of Spirovac at 20 weeks to assess antigen recall responses. Serum antibody responses were increased (P > 0.05) at 8 and 20 weeks after vaccination in cattle receiving inoculums containing leptospira antigens combined with water-oil-emulsion, poly(diaminosulfide) microparticles (PNSN-MP), or aluminum hydroxide and in cattle vaccinated with Spirovac. Humoral responses were predominantly IgG1 isotypes. Antigen-specific proliferative responses were detected after initial vaccination in cattle vaccinated with Spirovac, PNSN-MP and water-oil-water treatments. Most proliferative responses occurring within CD4+ and gamma delta T cell populations expressing CD45RO and CD25 markers, a response consistent with an effector memory phenotype. Antigen-specific immune responses were not detected in cattle vaccinated with VPEAR after initial inoculation, but were detected in the antigen recall responses. PBMCs from cattle vaccinated with Spirovac, oil-water-oil, or PNSN-MP treatments had increased (P < 0.05) IL-17A release after in vitro stimulation with leptospirosis antigens, whereas all groups produced IFN-γ and IL-17A after in vitro stimulation during the antigen recall response. Our data demonstrates that combining leptospirosis antigens with these adjuvants enhances immunogenicity in cattle.Interpretative Summary: Vaccination of livestock is a key mechanism for minimizing transmission of leptospirosis, a zoonotic disease. Leptospirosis vaccines for cattle need to be improved to provide greater levels of protection from kidney colonization, better immune responses, and protection against multiple serovars. This could be accomplished using new vaccine adjuvants. In this study, several novel adjuvants were evaluated for their ability to induce effective immune responses in cattle to leptospira antigens as compared to currently available vaccines. Data suggested that vaccines containing biodegradable polymer microparticles and oil-emulsion adjuvants induced similar or greater immune responses as compared to a commercial vaccine. Our data suggest these new vaccine formulations warrant further investigation as new vaccine formulations for cattle and other livestock.