Stabilised aluminium phosphate nanoparticles used as vaccine adjuvant.

Aluminium phosphate is a commonly used adjuvant consisting of heterogeneously sized aggregates up to several micrometers. However, aluminium phosphate nanoparticles may exhibit an improved adjuvant effect. In this study, nanoparticles were made by sonication of commercially available aluminium phosphate adjuvant, resulting in particles with a size (Z-average diameter) between 200-300 nm and a point of zero charge of 4.5. To prevent reaggregation, which occurred within 14 days, a screening of excipients was performed to identify stabilisers effective under physiological conditions (pH 7.4, 290 mOsm). The amino acids threonine, asparagine, and L-alanyl-L-1-aminoethylphosphonic acid (LAPA) stabilised sonicated aluminium phosphate. Particle sizes remained stable between 400-600 nm at 37 °C during 106 days. Contrarily, arginine induced strong reaggregation to a particle size larger than 1000 nm. The stability of aluminium phosphate nanoparticles was strongly affected by the pH. Aggregation mainly occurred below pH 7. The adsorption capacity, a potentially relevant parameter for adjuvants, was slightly reduced in the presence of asparagine, when using a model antigen (lysozyme). LAPA, arginine, threonine and aspartic acid reduced protein adsorption significantly. The adjuvant effect of aluminium phosphate nanoparticles was studied by immunisation of mice with diphtheria toxoid adjuvanted with the aluminium phosphate nanoparticles. The presence of LAPA, threonine, aspartic acid or asparagine did not alter diphtheria toxoid-specific antibody or toxin-neutralising antibody titres. Arginine increased diphtheria toxoid-specific antibody titres but not toxin-neutralising antibody titres. In conclusion, aluminium phosphate nanoparticles were stabilised by particular amino acids and induced an adjuvant effect comparable to that of aluminium phosphate microparticles.

Respiratory syncytial virus fusion nanoparticle vaccine immune responses target multiple neutralizing epitopes that contribute to protection against wild-type and palivizumab-resistant mutant virus challenge.

Human respiratory syncytial virus (RSV) is the leading cause of severe lower respiratory tract infections in newborns, young children, elderly, and immune-compromised. The RSV fusion (F) glycoprotein is a major focus of vaccine development and the target of palivizumab (Synagis®) which is licensed as an immuno-prophylactic for use in newborn children at high risk of infection. However, clinical use of a narrowly targeted monoclonal antibodies leads to the generation of escape mutant strains that are fully resistant to neutralization by the antibody. Herein, we evaluated the RSV F nanoparticle vaccine (RSV F vaccine), produced as near-full-length, pre-fusogenic F trimers that form stable protein-detergent nanoparticles. The RSV F vaccine induces polyclonal antibodies that bind to antigenic site II as well as other epitopes known to be broadly neutralizing. Cotton rats immunized with the RSV F vaccine produced antibodies that were both neutralizing and protected against wild-type RSV infection, as well as against a palivizumab-resistant mutant virus. Use of aluminum phosphate adjuvant with the RSV F vaccine increased site II antibody avidity 100 to 1000-fold, which correlated with enhanced protection against challenge. The breadth of the vaccine-induced antibody response was demonstrated using competitive binding with monoclonal antibodies targeting antigenic sites Ø, II, IV, and VIII found on pre-fusion and post-fusion conformations of RSV F. In summary, we found the RSV F vaccine induced antibodies that bind to conserved epitopes including those defined as pre-fusion F specific; that use of adjuvant increased antibody avidity that correlated with enhanced protection in the cotton rat challenge model; and the polyclonal, high-avidity antibodies neutralized and protected against both wild-type and palivizumab-resistant mutant virus. These data support the ongoing clinical development of the aluminum phosphate adjuvanted RSV F nanoparticle vaccine.

[Different aluminum adjuvants significantly enhances the effect of immunization on Brucella Omp31].

Objective To investigate the effect of aluminum phosphate (AP) and aluminum hydroxide (AH) as adjuvants on Brucella outer membrane protein 31 (Omp31) in inducing humoral and cellular immune responses and immune protection. Methods AP and AH adjuvants were prepared and separately mixed with Brucella Omp31 protein to measure the adsorption rates. The AP- and AH-absorbed Omp31 protein were intraperitoneally injected into BLAB/c mice at 0, 2, and 4 weeks, and meanwhile, unabsorbed Omp31 protein and PBS were used as controls. The levels of serum IgG, IgG1, IgG2a and genital tract secretion sIgA were determined by ELISA at 0, 2, 4 and 6 weeks. Spleen cells were collected for culture at 6 weeks, and the cells were stimulated by Omp31 for 48 hours followed by the analysis of IFN-γ and IL-10 levels in the supernatants by ELISA, and the determination of lymphocyte proliferation by CCK-8 assay. The mice were challenged with Brucella at 6 weeks, and bacterial content in spleen tissue was determined 1 and 2 weeks later. Results AP and AH could absorb over 70% and 85% of the Omp31 protein, respectively, for solutions at all the tested concentrations. ELISA suggested that serum IgG, IgG1, IgG2a and genital tract sIgA levels peaked 2 weeks after the last immunization for both AP and AH groups, and antibody level was higher in the AP and AH groups than the control groups, and higher in the AH group than in the AP group. CCK-8 assay showed that the proliferating rate of lymphocytes induced by the AH group was significantly higher than that by the AP group, and the AH group also showed significantly higher IFN-γ level in the supernatant than the AP group, but no significant difference in IL-10 level. The AH group had remarkably lower bacterial load in the spleen than the AP group 2 weeks after challenged by Brucella 16M strain. Conclusion Both AP and AH adjuvants effectively enhanced immunogenicity and immune protection of the Brucella Omp31 protein, and AH was superior to AP in this respect.

Immunization with Pseudomonas aeruginosa outer membrane vesicles stimulates protective immunity in mice.

Pseudomonas aeruginosa is an opportunistic pathogen responsible for a wide range of severe nosocomial and community acquired infections, these infections are major health problems for cystic fibrosis patients and immune-compromised individuals. The emergence of multidrug-resistant isolates highlights the need to develop alternative strategies for treatment of P. aeruginosa infections. Outer membrane vesicles (OMVs) are spherical nanometer-sized proteolipids that are secreted from numerous of pathogenic Gram-negative bacteria, and a number of studies have confirmed the protective efficacy for use of OMVs as candidate vaccines. In this study, OMVs from P. aeruginosa (PA_OMVs) were isolated, formulated with aluminum phosphate adjuvant and used as a vaccine in a mouse model of acute lung infection. The results confirmed that active immunization with PA_OMVs was able to reduce bacterial colonization, cytokine secretion and tissue damage in the lung tissue, thus protecting mice from lethal challenge of P. aeruginosa. Cytokines assay validated that immunization with PA_OMVs was efficient to induce a mixed cellular immune response in mice. Further, high level of specific antibodies was detected in mice immunized with PA_OMVs, and results from opsonophagocytic killing assay and passive immunization suggested that humoral immune response may be critical for PA_OMVs mediated protection. These findings demonstrated that PA_OMVs may be served as a novel candidate vaccine for the prevention of P. aeruginosa infection.

Can vitamin E and selenium alleviate the immunologic impact of aluminium on pregnant rats' spleens?

This study aimed to assess if simultaneous administration of vitamin E, selenium and aluminium could alleviate the latter's immunologic impact on the spleen. Twenty eight virgin albino Sprague Dawley rats were randomly divided into two main groups: control (n=12) and experimental (n=18). These groups were divided into two subgroups each. The first control group received distiled water and the second one vitamin E and selenium for 3months through intragastric tubes. Of the two experimental subgroups, the first received oral aluminium chloride (AlCl3) at a dose 150mg/kg of body weight/day, and the second received AlCl3 plus vitamin E and selenium for 3months. Sixteen (out of eighteen) subject rats became pregnant. At day 20 of gestation, dams were sacrificed, and spleens were dissected and processed for histologic examination with routine and immunohistologic staining and semi-quantitative assessment. Aluminium administration induced a significant decrease in the number and density of T-lymphocytes and macrophages in the spleen as well as splenic fibrosis during pregnancy. Vitamin E and selenium reduced but did not completely prevent these changes.

Evaluation of C-reactive protein as an inflammatory biomarker in rabbits for vaccine nonclinical safety studies.

INTRODUCTION: Inflammatory reactions are one of the potential safety concerns that are evaluated in the framework of vaccine safety testing. In nonclinical studies, the assessment of the inflammation relies notably on the measurement of biomarkers. C-reactive protein (CRP) is an acute-phase plasma protein of hepatic origin that could be used for that purpose in toxicity studies with rabbits. METHODS: To evaluate the utility of CRP as an additional inflammatory biomarker in adjuvant or vaccine toxicity studies, rabbits were injected on Day 0 with saline, aluminium phosphate, aluminium hydroxide, Adjuvant System (AS)01, AS03, AS15, or diphtheria-tetanus-whole cell pertussis-hepatitis B vaccine (DTPw-HB). Body weights, haematology parameters, CRP and fibrinogen levels were measured daily up to Day 7. Macroscopic changes at the injection site were also evaluated up to Day 7. At Day 7, a histopathological examination of the injection site was performed. RESULTS: Like fibrinogen, CRP levels rapidly increased after the injection of Adjuvant Systems or DTPw-HB, peaking at Day 1, and returning to baseline in less than a week. The magnitude of the CRP increase was consistently higher than that of fibrinogen with a larger fold increase from background, providing a more sensitive evaluation. The number of circulating heterophils was also increased on Day 1 after the injection of Adjuvant Systems or DTPw-HB. The highest increases in CRP levels were observed after the injection of DTPw-HB or AS03, and were also associated with the persistence of mixed inflammatory cell infiltrates (including heterophils) at the injection sites on Day 7. No increases in CRP levels and in circulating heterophils were observed after injection of the aluminium salt adjuvants. DISCUSSION: Our study supports the use of CRP as an accurate biomarker of acute inflammation in rabbits for vaccine toxicity studies and highlights an association between increased CRP levels and the recruitment of heterophils.

Preformulation characterization of an aluminum salt-adjuvanted trivalent recombinant protein-based vaccine candidate against Streptococcus pneumoniae.

The preformulation of a trivalent recombinant protein-based vaccine candidate for protection against Streptococcus pneumoniae is described both in the presence and in the absence of aluminum salt adjuvants. The biophysical properties of the three protein-based antigens, fragments of pneumococcal surface adhesion A (PsaA), serine-threonine protein kinase (StkP), and protein required for cell wall separation of group B streptococcus (PcsB), were studied using several spectroscopic and light scattering techniques. An empirical phase diagram was constructed to assess the overall conformational stability of the three antigens as a function of pH and temperatures. A variety of excipients were screened on the basis of their ability to stabilize each antigen using intrinsic fluorescence spectroscopy and circular dichroism spectroscopy. Sorbitol, sucrose, and trehalose stabilized the three proteins in solution. The addition of manganese also showed a drastic increase in the thermal stability of SP1650 in solution. The adsorption and desorption processes of each of the antigens to aluminum salt adjuvants were evaluated, and the stability of the adsorbed proteins was then assessed using intrinsic fluorescence spectroscopy and Fourier transform infrared spectroscopy. All the three proteins showed good adsorption to Alhydrogel. PsaA was destabilized when adsorbed onto Alhydrogel® and adding sodium phosphate showed a stabilizing effect. PcsB was found to be stabilized when adsorbed to Alhydrogel®, and no destabilizing or stabilizing effects were seen in the case of StkP.

A novel adjuvant, mixture of alum and the beta-adrenergic receptor antagonist propranolol, elicits both humoral and cellular immune responses for heat-killed Salmonella typhimurium vaccine.

OBJECTIVE: To determine the efficacy of the mixture of propranolol (PRP), a beta-adrenergic receptor antagonist, and alum, as a new adjuvant, in the induction of humoral and cellular immunity in response to heat-killed Salmonella typhimurium (S. typhimurium) (HKST) as a model vaccine. METHODS: BALB/c mice were divided into five groups. Mice in the experimental groups received either the HKST vaccine alone or in combination with the adjuvant alum, PRP or the alum-PRP mixture. Mice in the negative control group received phosphate-buffered saline. All mice were immunized two times on days 0 and 14. Two weeks after the last immunization, immune responses to S. typhimurium were assessed. RESULTS: Administration of the alum-PRP mixture as an adjuvant increased the ability of the HKST vaccine to enhance lymphocyte proliferation, shifted the immune response towards a T-helper (Th) 1 pattern and increased S. typhimurium specific IgG, IgG2a and IgG1. This resulted in improved protective immunity against S. typhimurium. CONCLUSION: Administration of the alum-PRP mixture as an adjuvant in combination with the HKST vaccine, can enhance both humoral and cellular immunity and shift the immune responses to a Th1 pattern.

The role of adjuvants in vaccines for seasonal and pandemic influenza.

Current seasonal influenza vaccines aim to induce high-titred virus-neutralizing antibody to the viral hemagglutinin (HA), which is the best form of protection against infection, but these vaccines can be poorly efficacious in the elderly and other target groups that rely on them most. Furthermore, little cross-protection is provided against significantly drifted strains and even less against different subtypes of virus with pandemic potential. Adjuvants could theoretically have two different roles in improving control of influenza through vaccination. Firstly, a role in enhancing the antibody response in situations where the split virus preparation is poorly immunogenic or if there is an imperative to provide "dose sparing" in the context mass vaccination with a virus to which the population is immunologically naïve. Secondly, adjuvants could be used to allow induction of additional arms of the immune response that are not stimulated by current split virus vaccines. Briefly reviewed here are our efforts to investigate the role of adjuvants in both these contexts.

Mechanism of immunopotentiation by aluminum-containing adjuvants elucidated by the relationship between antigen retention at the inoculation site and the immune response.

The relationship between depot formation and immunopotentiation was studied by comparing the retention of antigen at the inoculation site with antibody production in rats. A model (111)In-labeled alpha casein (IDCAS) antigen was formulated into four vaccines: IDCAS adsorbed onto either aluminum hydroxide adjuvant (AH) or aluminum phosphate adjuvant (AP); non-adsorbed IDCAS with phosphate-treated AP (PTAP); and IDCAS solution. Gamma scintigraphy showed the order of retention following subcutaneous administration to be: AH adsorbed>AP adsorbed>non-adsorbed with PTAP=solution. The antibody titers followed the order: non-adsorbed with PTAP=AP adsorbed>AH adsorbed>>solution. The presence of an aluminum-containing adjuvant was essential for immunopotentiation, but retention of the antigen at the inoculation site was not required.

The immunobiology of aluminium adjuvants: how do they really work?

Aluminium adjuvants potentiate the immune response, thereby ensuring the potency and efficacy of typically sparingly available antigen. Their concomitant critical importance in mass vaccination programmes may have prompted recent intense interest in understanding how they work and their safety. Progress in these areas is stymied, however, by a lack of accessible knowledge pertaining to the bioinorganic chemistry of aluminium adjuvants, and, consequently, the inappropriate application and interpretation of experimental models of their mode of action. The objective herein is, therefore, to identify the many ways that aluminium chemistry contributes to the wide and versatile armoury of its adjuvants, such that future research might be guided towards a fuller understanding of their role in human vaccinations.

Comparative study of the effects of aluminum adjuvants and Freund's incomplete adjuvant on the immune response to an Edwardsiella tarda major antigen.

Edwardsiella tarda is a severe aquaculture pathogen that can infect many different fish species cultured worldwide. Et49 is a major E. tarda antigen with weak immunoprotective potential. In this study, using Et49 as an example vaccine, the adjuvanticity of Freund's incomplete adjuvant (FIA), aluminum hydroxide, and aluminum phosphate adjuvant were evaluated in a Japanese flounder model. The results showed that the presence of FIA, aluminum hydroxide, and aluminum phosphate adjuvant increased the relative percent of survival of Et49-vaccinated fish by 47%, 19%, and 35%, respectively. Fish vaccinated with FIA-adjuvanted Et49 exhibited longer persistence of vaccine at the injection site and more severe intra-abdominal lesions than fish vaccinated with aluminum-adjuvanted Et49. Both aluminum adjuvants and, to a lesser degree, FIA augmented the production of specific serum antibodies, which reached the highest levels at 6 and 7 weeks post-vaccination. Passive immunization of Japanese flounder with sera from fish vaccinated with aluminum- and FIA-adjuvanted Et49 induced no protection against lethal E. tarda challenge. Examination of the transcription profile of immune-related genes showed that vaccination with aluminum-adjuvanted Et49 significantly enhanced the expression of the genes that are associated mainly with humoral immunity, whereas vaccination with FIA-adjuvanted Et49 induced the expression of a much broader spectrum of genes that are likely to be involved in humoral and innate cellular immunity. These results provide new insights to the action mechanisms of FIA and aluminum adjuvants in Japanese flounder and may be useful for the selection of adjuvant for vaccine formulations intended for Japanese flounder.

A dose-ranging study of a subunit Respiratory Syncytial Virus subtype A vaccine with and without aluminum phosphate adjuvantation in adults > or =65 years of age.

We studied the safety and immunogenicity of a Respiratory Syncytial Virus (RSV)-A vaccine containing subunit antigens F, G and M in older persons, and its effect on influenza vaccine immunogenicity. In a dose-ranging, placebo-controlled, blinded trial 561 adults > or =65 years of age at five Canadian sites were randomized to one intramuscular injection of either 100, 50 or 25 microg RSV-A-alum vaccine or 100 microg non-adjuvanted RSV-A vaccine, or alum-placebo. All participants were offered inactivated influenza vaccine on day 32. Immunization was well tolerated and reactogenicity was similar between the RSV and influenza vaccines and the alum-placebo. Only the 100 microg non-adjuvanted RSV vaccine achieved the primary immunogenicity outcome of eliciting a > or =4-fold rise in neutralizing antibody (NA) titres against RSV-A in > or =50% of participants at day 32. Geometric mean titres against RSV-A and -B at all points were comparable in 100 microg adjuvanted and non-adjuvanted groups. At day 32, a > or =4-fold haemagluttinin inhibition (HI) antibody response or HI > or =40 to Influenza (A-H3N2) was seen in >74% of participants; no difference was seen between groups. A subunit non-alum-containing RSV-A vaccine was well tolerated in a large population > or =65 years and did not interfere with influenza vaccine immunogenicity. This RSV-A-based vaccine demonstrated NA rise which could provide seasonal protection against severe RSV illnesses from RSV-A or -B and warrants further testing to determine its efficacy in the prevention of clinical illness in elderly persons.

Comparison of the adjuvanticity of aluminum salts and their combination in hepatitis B recombinant protein vaccine in assessed mice.

BACKGROUND: Several adjuvants have been evaluated for vaccine formulations but aluminum salts will continue to be used for many years due to their safety, low cost and adjuvanticity with different antigens. Two commonly used aluminum adjuvants, aluminum hydroxide and aluminum phosphate have different adjuvanticity properties. Commercial recombinant protein hepatitis B vaccines containing aluminum hydroxide is facing low induction of immunity in some sections of the vaccinated population. OBJECTIVE: In this study, to follow the current global efforts in finding more potent hepatitis B vaccine formulations, adjuvanticity of aluminum phosphate, aluminum hydroxide and their combinations has been evaluated. METHODS: The formulated vaccines were administered intra-peritoneally (i.p.) to BALB/c mice and the titer of antibody was determined after 28 days using ELISA technique. The geometric mean of antibody titer (GMT, mIU/ml), seroconversion and seroprotection rates, ED50 (ng) and relative potency (microg/dose) of different formulations were determined. RESULTS: GMT of antibody titer, seroconversion and seroprotection rates showed significantly higher adjuvanticity for aluminum phosphate than other formulations. The ED50 of aluminum phosphate was approximately two fold less than other formulations. CONCLUSION: Aluminum phosphate showed more adjuvanticity than aluminum hydroxide and their combinations in hepatitis B protein vaccine. The use of aluminum phosphate as adjuvant leads to higher immunity which may result in more protective response in vaccinated groups.

Relationship between physical and chemical properties of aluminum-containing adjuvants and immunopotentiation.

Aluminum-containing adjuvants are an important component of many vaccines because they safely potentiate the immune response. The structure and properties of aluminum hydroxide adjuvant, aluminum phosphate adjuvant and alum-precipitated adjuvants are presented in this review. The major antigen adsorption mechanisms, electrostatic attraction and ligand exchange, are related to the adjuvant structure. The manner by which aluminum-containing adjuvants potentiate the immune response is related to the structure, properties of the adjuvant and adsorption mechanism. Immunopotentiation occurs through the following sequential steps: inflammation and recruitment of antigen-presenting cells, retention of antigen at the injection site, uptake of antigen, dendritic cell maturation, T-cell activation and T-cell differentiation.

Fusion of antigen to Fas-ligand in a DNA vaccine enhances immunogenicity.

DNA vaccines have considerable potential for the prophylaxis and therapy of a range of diseases, but their potential has not been realised largely due to poor immunogenicity. Fas ligand is a pro-apoptotic molecule, able to induce death of Fas expressing cells. We describe the construction of a DNA vaccine encoding a chimeric fusion between Fas ligand and a truncated version of HIV gp120 as a model antigen. The fusion DNA was used as a priming vaccine, along with boosting with recombinant gp120 protein. Priming with fusion protein DNA resulted in a powerful enhancement of immune responses to the protein boost, and, in the presence of aluminum phosphate, to a strong enhancement in T helper 2 type responses. Fas ligand delivered in a separate plasmid also had an adjuvant effect, although it was weaker than that delivered by the fusion protein.

Influence of aluminum-based adjuvant on the immune response to multiantigenic formulation.

Several adjuvants have been described and tested in humans. However, the aluminum-based adjuvants remain the most widely used component in vaccines today. Emerging data suggest that aluminum phosphate and aluminum hydroxide adjuvants do not promote a strong commitment to the helper T cell type 2 (Th2) pathway when they are coadministered with some Th1 adjuvants. In this regard, subtle differences between both aluminum-based adjuvants have been demonstrated. We have previously shown that subcutaneous immunization, in aluminum phosphate, of a mixture comprising the surface and core antigens of hepatitis B virus (HBV) and the multiepitopic protein CR3 of human immunodeficiency virus type 1 elicits a CR3-specific Th1 immune response. In these experiments, the antigens were adjuvated at the same time. As the final selection of the best adjuvant should be based on experimental evidence, we asked whether aluminum hydroxide allows a better Th1 immune deviation than aluminum phosphate. We also studied several ways to mix the antigens and the impact on CR3-specific interferon (IFN)-gamma secretion. Our findings indicate that aluminum hydroxide allows better Th1 immunodeviation than aluminum phosphate adjuvant for the mixture of HBV antigens and CR3. In addition, CR3-specific IFN-gamma secretion of the various formulations tested was the same irrespective of the order in which the antigens were combined.

Codelivery of a DNA vaccine and a protein vaccine with aluminum phosphate stimulates a potent and multivalent immune response.

The study explores the possibility of efficiently codelivering DNA vaccines and protein-based vaccines by formulation with aluminum phosphate (AlPO4). When mixed with aluminum adjuvants, plasmid DNA bound tightly onto aluminum hydroxide [Al(OH)3] but not to AlPO4. Different doses of DNA vaccines formulated with AlPO4 [but not Al(OH)3] induced enhanced humoral responses and supported priming of MHC class I restricted cellular immunity. Different proteins mixed with the plasmid DNA vaccine in the AlPO4 formulation did not impair its immunogenicity. Coinjection of two different vaccine-relevant antigens in the same AlPO4 formulation, one as a DNA vaccine and the other as a recombinant protein, elicited polyvalent, humoral, and cellular immune responses to all antigens delivered. The isotype profiles of the induced humoral responses and the cytokine profiles of the specifically primed T cell responses indicated that the combined vaccines supported copriming of Th1- and Th2-biased as well as balanced responses. These findings indicate that the AlPO4 adjuvant, a widely accepted adjuvant in human vaccination practice, can be used to combine protein- and DNA-based vaccination to prime an enhanced and balanced specific immunity.

Enhancement of humoral immune responses to a human cytomegalovirus DNA vaccine: adjuvant effects of aluminum phosphate and CpG oligodeoxynucleotides.

A human cytomegalovirus (HCMV) glycoprotein B (gpUL55) DNA vaccine has been evaluated in BALB/c mice. Intramuscular immunization of these mice with pRc/CMV2-gB resulted in the generation of high levels of gpUL55-specific antibody (geometric mean titer [GMT] 1:8900) and neutralizing antibody (GMT 1:74) after 2 booster doses given 5 and 10 weeks after primary inoculation. Emulsifying the construct with the aluminum phosphate gel adjuvant Adju-Phos before immunization enhanced gpUL55-specific antibody responses (GMT 1:17800, P = 0.04). Co-immunization with CpG oligodeoxynucleotides was shown to enhance levels of neutralizing antibodies generated by immunization of mice with a pRc/CMV2-gB/Adju-Phos emulsion (P = 0.04). The results provide a rationale for evaluating combinations of other HCMV proteins for incorporation into a multi-target DNA vaccine, and for the optimization of adjuvant usage, to elicit enhanced levels of neutralizing antibodies. 2003.

Effect of monophosphoryl lipid A (MPL) on T-helper cells when administered as an adjuvant with pneumocococcal-CRM197 conjugate vaccine in healthy toddlers.

As new vaccines are developed, novel adjuvants may play an important role in eliciting an effective immune response. We evaluated the safety and adjuvant properties of monophosphoryl lipid A (MPL in 129 healthy toddlers immunized with two doses of nine-valent pneumococcal-CRM(197) protein conjugate vaccine (PCV9) combined with 10, 25, or 50 micro g of MPL with or without alum (AlPO(4)). Vaccine-specific humoral and cell-mediated responses were examined following the second dose of study vaccine. All doses of MPL were well-tolerated and a dose-dependent effect of MPL on specific cellular responses was observed. The 10 micro g MPL dose significantly enhanced CRM(197)-specific T-cell proliferation (P=0.02) and interferon-gamma (INF-gamma) production (P=0.009) compared to responses of controls who received PCV9 with AlPO(4). In contrast, CRM(197)-specific T-cell proliferation and interferon-gamma production of the 50 micro g MPL/AlPO(4) group were decreased when compared to controls although these differences did not reach statistical significance. IL-5 and IL-13 responses after immunization showed a similar pattern with increased production in the 10 micro g MPL group and decreased production in the 50 micro g MPL/AlPO(4) group compared to controls. There were no differences in serum IgG antibody concentrations to the nine vaccine pneumococcal capsular polysaccharides and carrier protein between the MPL-containing and control vaccine groups. These findings demonstrate a dose-dependent effect of MPL on T-helper cell type 1 (TH-1) responses to the carrier protein and also suggest an effect on T-helper cell type 2 (TH-2) responses.