Salivary IgA Antibody Responses Research Articles

Salivary IgA and IgG Antibody Responses against Periodontitis-Associated Bacteria in Crohn's Disease.

Elevated serum immunoglobulin (Ig) antibody levels are observed in Crohn's disease patients. The aim of this study was to evaluate the salivary IgA and IgG antibody levels against Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia in Crohn's disease patients. Eighty-eight participants (47 Crohn's disease patients and 41 systemically healthy age- and gender-matched controls) were included in the study. Oral and medical health statuses were recorded and salivary samples were collected. Salivary P. gingivalis, T. forsythia, A. actinomycetemcomitans, and P. intermedia carriage were analyzed with DNA sequencing technique, salivary levels of IgG1, IgG2, IgG3, IgG4, and IgM were measured with the Luminex® xMAP™ technique, and salivary IgA and IgG antibody levels against P. gingivalis, T. forsythia, A. actinomycetemcomitans, and P. intermedia were detected by ELISA. As result, higher salivary IgG2 (p = 0.011) and IgG3 (p = 0.006), P. gingivalis IgA (p < 0.001), A. actinomycetemcomitans IgG (p = 0.001), and P. intermedia IgG (p < 0.001) antibody levels were detected in the Crohn's disease group compared to the controls. Salivary P. gingivalis carriage was lower in the Crohn's disease group in comparison to the controls (p = 0.024). In conclusion, salivary IgA antibody responses against P. gingivalis and IgG antibody responses against P. intermedia have independent associations with Crohn's disease.

Sublingual immunization with recombinant GroEL plus CpG-ODN inhibits Porphyromonas gingivalis-induced inflammation and alveolar bone loss.

It has been reported that GroEL, a heat shock protein (HSP) produced by the representative periodontopathogenic bacterium, Porphyromonas gingivalis, induces inflammation-induced osteoclastogenesis and promotes alveolar bone resorption. In this study, we demonstrated the efficacy of a mucosal vaccine targeting GroEL against bone resorption induced by P. gingivalis. Female BALB/c mice received sublingual CpG oligodeoxynucleotide as an adjuvant with recombinant GroEL (rGroEL) prior to P. gingivalis exposure. Animals were euthanized 30 days after P. gingivalis inoculation. Sublingual immunization (SLI) with rGroEL elicited significant rGroEL-specific serum immunoglobulin (Ig)G and salivary IgA antibody (Ab) responses, and these responses were sustained for approximately 1 year. Interestingly, 10-fold more GroEL-specific IgA Ab-producing cells were detected in the submandibular glands (SMGs) than in the spleen. Antigen (Ag)-specific cells isolated from the spleen and SMGs induced significantly higher levels of IFN-γ expression after Ag restimulation in vitro. Flow cytometry illustrated that the frequency of CD11b+ dendritic cells with enhanced expression of CD80, CD86, CD40, and major histocompatibility complex II molecules was significantly increased in the SMGs. Furthermore, SLI with rGroEL significantly suppressed P. gingivalis-induced alveolar bone resorption and P. gingivalis-stimulated tumor necrosis factor-α, interleukin-6, and HSP60 expression in the gingiva. These findings suggest that SLI with rGroEL and CpG oligodeoxynucleotide is a beneficial strategy for preventing periodontal disease, mainly by presenting Ags in the oral region and inducing antibody production in the mucosal and systemic systems.

Relationship between the IgA antibody response against Streptococcus mutans GbpB and severity of dental caries in childhood

ObjectiveExplore the associations between the severity of dental caries in childhood, mutans streptococci (MS) levels and IgA antibody response against Streptococcus mutans GbpB. Moreover, other caries-related etiological factors were also investigated. Design36–60 month-old children were grouped into Caries-Free (CF, n=19), Early Childhood Caries (ECC, n=17) and Severe Early Childhood Caries (S-ECC, n=21). Data from socio-economic-cultural status, oral hygiene habits and dietary patterns were obtained from a questionnaire and a food-frequency diary filled out by parents. Saliva was collected from children for microbiological analysis and detection of salivary IgA antibody reactive with S. mutans GbpB in western blot. ResultsS-ECC children had reduced family income compared to those with ECC and CF. There was difference between CF and caries groups (ECC and S-ECC) in MS counts. Positive correlations between salivary IgA antibody response against GbpB and MS counts were found when the entire population was evaluated. When children with high MS counts were compared, S-ECC group showed significantly lower IgA antibody levels to GbpB compared to CF group. This finding was not observed for the ECC group. ConclusionsThis study suggests that children with S-ECC have reduced salivary IgA immune responses to S. mutans GbpB, potentially compromising their ability to modify MS infection and its cariogenic potential. Furthermore, a reduced family income and high levels of MS were also associated with S-ECC.

Observations on the phenotypic relationships between anti-CarLA salivary IgA antibody response, nematode infection levels and growth rates in farmed red (Cervus elaphus) and wapiti hybrid deer (Cervus elaphus canadensis)

Nematode parasites are one of the most significant production limiting factors in farmed deer in New Zealand. One long term strategy to reduce reliance on anthelmintics is to select deer that develop resistance to parasites. It has been shown in sheep that secretory antibody (IgA) in the saliva against a Carbohydrate Larval Antigen (CarLA) on infective larvae (L3) of a wide range of gastro-intestinal nematodes protects against reinfection. This paper describes a longitudinal slaughter study undertaken to measure anti-CarLA IgA antibody (CarLA-IgA) levels in the saliva of 5–12 month old farmed red and wapiti-cross-red deer (wapx) grazed together and to attempt to relate these levels to parasite burdens and productivity.The study showed that salivary CarLA-IgA levels peaked in June (late autumn) and October (mid spring), but the levels in wapx deer were significantly lower than in red deer. Over the May–December period 55% of red deer had CarLA-IgA values ≥2 units compared with 26% of wapx deer and over this period red deer had consistently lower adult abomasal parasite burdens than wapx deer. The average number of adult abomasal nematodes was significantly lower at each slaughter from May to December for all deer with CarLA-IgA ≥2 units vs <2 units. There were no demonstrable correlations with liveweight gain in these small groups of deer.

Salivary IgA antibody responses to Streptococcus mitis and Streptococcus mutans in preterm and fullterm newborn children

ObjectivesThe intensities and specificities of salivary IgA antibody responses to antigens of Streptococcus mutans, the main pathogen of dental caries, may influence colonization by these organisms during the first 1.5 year of life. Thus, the ontogeny of salivary IgA responses to oral colonizers continues to warrant investigation, especially with regard to the influence of birth conditions, e.g. prematurity, on the ability of children to efficiently respond to oral microorganisms. In this study, we characterised the salivary antibody responses to two bacterial species which are prototypes of pioneer and pathogenic microorganisms of the oral cavity (Streptococcus mitis and Streptococcus mutans, respectively) in fullterm (FT) and preterm (PT) newborn children. MethodsSalivas from 123 infants (70 FT and 53 PT) were collected during the first 10h after birth and levels of IgA and IgM antibodies and the presence of S. mutans and S. mitis were analysed respectively by ELISA and by chequerboard DNA–DNA hybridization. Two subgroups of 24 FT and 24 PT children were compared with respect to patterns of antibody specificities against S. mutans and S. mitis antigens, using Western blot assays. Cross-adsorption of 10 infant's saliva was tested to S. mitis, S. mutans and Enterococcus faecalis antigens. ResultsSalivary levels of IgA at birth were 2.5-fold higher in FT than in PT children (Mann–Whitney; P<0.05). Salivary IgA antibodies reactive with several antigens of S. mitis and S. mutans were detected at birth in children with undetectable levels of those bacteria. Adsorption of infant saliva with cells of S. mutans produced a reduction of antibodies recognizing S. mitis antigens in half of the neonates. The diversity and intensity of IgA responses were lower in PT compared to FT children, although those differences were not significant. ConclusionThese data provide evidence that children have salivary IgA antibodies shortly after birth, which might influence the establishment of the oral microbiota, and that the levels of salivary antibody might be related to prematurity.

A targeted fimA DNA vaccine prevents alveolar bone loss in mice after intra-nasal administration

To construct a dendritic cell (DC)-targeted DNA vaccine against FimA of Porphyromonas gingivalis and evaluate the immunogenicity and protection in mice. A targeted DNA plasmid pCTLA4-FimA, which encodes the signal peptide and extracellular regions of mouse cytotoxic T lymphocyte-associated antigen 4 (CTLA4), the hinge and Fc regions of human Igγ1 and FimA of P. gingivalis, was constructed. Mice were immunized with pCTLA4-FimA, the non-targeted DNA plasmid pFimA, which contains only fimA gene, or pCI vector intra-nasally. Serum and saliva antibody responses were detected by enzyme-linked immunosorbent assay. The protection against P. gingivalis-induced periodontitis was evaluated by measuring alveolar bone loss in mice. Mice immunized with pCTLA4-FimA showed elevated levels of specific serum IgG and salivary IgA antibody responses compared with mice immunized with pFimA (p<0.01). Both pFimA and pCTLA4-FimA immunized groups showed significantly lower alveolar bone loss, with the magnitude protection greater in the latter (p<0.01), compared with the pCI immunized group. The DC-targeted DNA construct pCTLA4-FimA enhanced both systemic and mucosal immunity following intra-nasal immunization. A DNA-based immunization strategy may be an effective way to attenuate periodontitis induced by P. gingivalis.

T Helper Cytokine Responses Induced by Nasal Immunization with Glucosyltransferase-I of Streptococcus sobrinus

Our previous study showed that nasal immunization with glucosyltransferase-I (GTF-I) produced by Streptococcus sobrinus elicits serum IgG, serum IgA, and salivary IgA antibody responses that provide protection against dental caries caused by S. sobrinus infection. In this study, to develop an effective vaccine for the prevention of dental caries, we assessed T helper (Th) cell responses in systemic and mucosal compartments when GTF-I was administered nasally. When CD4+ T cells isolated from the spleen or cervical lymph nodes of mice immunized with GTF-I alone or GTF-I plus unmethylated cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODN) were re-stimulated with GTF-I in vitro, significant levels of proliferative responses were induced. Analysis of Th1 (IFN-γ) and Th2 (IL-4) cytokine responses showed that GTF-I-specific Th cells from mice given GTF-I alone produced a significant level of IL-4 with low IFN-γ. On the other hand, CD4+ T cells from mice given GTF-I plus CpG ODN produced increased levels of IFN-γ when compared with those of mice given GTF-I alone, whereas the IL-4 production was not changed. The IgG subclass responses confirmed the cytokine profile, showing that while nasal GTF-I elicited mainly IgG1 antibodies, GTF-I plus CpG ODN further enhanced IgG2a and IgG2b, but not IgG1, antibody responses. These results suggest that nasal immunization with GTF-I elicits GTF-I-specific Th2 cytokine responses in both mucosal and systemic lymphoid tissues and that CpG ODN as an adjuvant enhances Th1-type cytokine responses to co-administered GTF-I.

A Fusion Protein of the Hemagglutinin A Antigenic Region of Porphyromonas gingivalis and Maltose-Binding Protein Induces Antibody Responses in the Oral Cavity

Maltose-binding protein (MBP) produced by Escherichia coli acts as an adjuvant when fused to various antigens. In this study, the antigenic region of hemagglutinin A of Porphyromonas gingivalis with a molecular mass of 25 kDa (25k-hagA) was fused to MBP (25k-hagA-MBP) and the efficacy of the resulting fusion protein as a nasal vaccine was assessed. While nasal immunization with 25k-hagA induced no antibody responses, 25k-hagA-MBP elicited high serum IgG, IgA, and secretory IgA anti-25k-hagA antibodies in the saliva. When 25k-hagA-MBP was co-administered with an established mucosal adjuvant, cholera toxin, 25k-hagA-specific serum IgG and salivary IgA antibody responses were not further elevated. Interestingly, 25k-hagA mixed with MBP failed to induce 25k-hagA-specific antibody responses. These findings suggest that MBP must be fused to the target antigen for induction of antigen-specific antibody responses and that nasal administration of 25k-hagA-MBP may be an effective mucosal vaccine for the prevention of P. gingivalis infection.

Nasal Administration of Glucosyltransferase-I of Streptococcus Sobrinus without Adjuvant Induces Protective Immunity

This study seeks to assess the efficacy of the glucosyltransferase-I (GTF-I) produced by Streptococcus sobrinus as a nasal vaccine for the prevention of dental caries. Nasal immunization of mice with GTF-I elicited significant levels of GTF-I-specific IgG and IgA in serum and mucosal IgA antibodies in saliva. Antibody-forming cell analysis confirmed the antibody titers by detecting high numbers of GTF-I-specific antibody-forming cells in spleen and salivary glands. Coadministration of GTF-I and oligodeoxynucleotides (ODN) containing unmethylated cytosine-phosphate-guanine (CpG) dinucleotides (CpG ODN) as adjuvant further elevated salivary IgA antibody responses; however, the increase in serum antibody levels was slight. GTF-I-specific IgG antibodies from mice given GTF-I alone or GTF-I plus CpG ODN inhibited biofilm formation by S. sobrinus. Finally, the mice given nasal GTF-I showed protection and significant inhibition of dental caries caused by oral infection with S. sobrinus even without the use of CpG ODN. These results suggest that nasal administration of GTF-I could be an important tool for the prevention of dental caries.

Nasal immunization with a 40-kDa Outer Membrane Protein of Porphyromonas gingivalis Inhibits Atherosclerotic Plaque Accumulation Caused by Oral P. gingivalis Infection

In this study, we assessed the potential of a nasal vaccine against oral Porphyromonas gingivalis infection for the prevention of P. gingivalis-accelerated atherosclerosis. Apolipoprotein E-deficient spontaneously hyperlipidemic (Apoeshl) mice were nasally immunized with the 40-kDa outer membrane protein (40k-OMP) of P. gingivalis plus cholera toxin (CT) as adjuvant and then challenged orally with P. gingivalis. Atheromatous lesions in the proximal aorta of each animal were analyzed histomorphometrically and the serum concentrations of 40k-OMP-specific antibodies were examined. Oral infection of Apoeshl mice with P. gingivalis resulted in increased alveolar bone loss. Furthermore, the areas of the aortic sinus that were covered with atherosclerotic plaque were increased in those infected mice when compared with non-infected, control mice. However, nasal immunization of Apoeshl mice with 40k-OMP plus CT as adjuvant induced significant levels of 40k-OMP-specific serum IgG and salivary IgA antibody responses. Interestingly, when Apoeshl mice were nasally immunized with 40k-OMP plus CT before the infection, alveolar bone loss as along with atherosclerotic plaque accumulation in the aortic sinus were significantly reduced. These results suggest that oral infection with P. gingivalis accelerates atherosclerosis in Apoeshl mice and that 40k-OMP plus CT may be an effective nasal vaccine for the prevention of atherosclerosis accelerated by P. gingivalis infection.

Protective efficacy of a targeted anti-caries DNA plasmid against cariogenic bacteria infections

We have previously reported that a targeted anti-caries DNA plasmid pGJA-P/VAX which was constructed against the antigenic determinants of Streptococcus mutans ( S. mutans) successfully induced antibody responses in mice and monkeys. The present study explored the protective efficacy of pGJA-P/VAX against cariogenic bacterial challenge. Groups of rats were orally challenged with S. mutans or Streptococcus sobrinus ( S. sobrinus) and then immunized with pGJA-P/VAX or the vector pVAX1 intranasally. Serum IgG and salivary IgA antibody levels were assessed by an enzyme-linked immunosorbent assay and caries activity was evaluated by the Keyes method. The results showed that specific salivary IgA antibody responses were induced following intranasal vaccination with pGJA-P/VAX. Moreover, immunization with pGJA-P/VAX resulted in significantly reduced enamel and dentinal caries lesions in rats after S. mutans infection and significantly reduced enamel caries lesions after S. sobrinus infection. Thus, pGJA-P/VAX was not only protective toward S. mutans infection, but also provided cross-strain protection against S. sobrinus infection in rats.

Immunogenicity and Protective Efficacy of a Targeted Fusion DNA Construct against Dental Caries

Targeting antigens to antigen-presenting cells by fusion to cytotoxic T lymphocyte-associated antigen 4 (CTLA4) has been shown to be a highly efficient method to enhance the efficacy of DNA vaccines. The purpose of this study was to determine the immunogenicity and protective efficacy of the targeted fusion DNA construct pGJA-P, which contains the signal peptide and extracellular regions of human CTLA4 gene, the hinge and Fc regions of human Igγ₁ gene, the glucan-binding domain of the Streptococcus mutans gtfB gene and the A-P fragment of the S. mutans pac gene, compared with the fusion DNA construct pGLUA-P, which contains only the glucan-binding domain of the S. mutansgtfB gene and the A-P fragment of the S. mutans pac gene. BALB/c mice were immunized with pGJA-P, pGLUA-P, or pCI (vector) by the intramuscular or intranasal route. Specific anti-PAc and anti-GTF-I serum IgG and salivary IgA antibody responses were assessed by an enzyme-linked immunosorbent assay. Wistar rats were orally challenged with S. mutans and immunized with pGJA-P, pGLUA-P, or pCI intramuscularly or intranasally, and caries activity was evaluated by the Keyes method. pGJA-P induced accelerated and increased serum and salivary antibody responses in mice compared with pGLUA-P. Rats immunized with pGJA-P had significantly fewer caries lesions than rats immunized with pGLUA-P (p < 0.01). Thus, this study demonstrates that the targeted DNA construct pGJA-P can enhance both systemic and mucosal immunity and may be a useful strategy for improving the protective efficacy of anticaries DNA vaccines.

Remote glucosyltransferase-microparticle vaccine delivery induces protective immunity in the oral cavity.

Intranasally administered dental caries vaccines show significant promise for human application. Alternate mucosal routes may be required, however, to induce caries-protective salivary IgA antibody in children with respiratory diseases. Since rectal mucosa contains inductive lymphoid tissue, we hypothesized that the rectal route could be used to induce salivary immunity to mutans streptococcal glucosyltransferase (GTF), resulting in protective immunity to experimental dental caries. We first explored the ability of glucosyltransferase, incorporated into polylactide-co-glycolide (PLGA) microparticles (MP), and administered rectally together with mucosal adjuvant, to induce a salivary IgA antibody response. Groups of Sprague-Dawley rats (6/group) were immunized rectally on days 0, 7, 14 and 21 with a) GTF-MP alone, b) GTF-MP with cholera toxin, c) GTF-MP with detoxified mutant Escherichia coli toxin (dLT), or d) sham immunized with PLGA and cholera toxin. An additional group was immunized intranasally with GTF-MP alone. Saliva and nasal washes of all intranasally immunized rats contained IgA antibody to glucosyltransferase on day 28. Salivary IgA antibody was also detected in 7/12 rats rectally immunized with GTF-MP and cholera toxin or dLT, although responses were lower than those obtained by intranasal immunization. Most fecal extracts from rectally delivered GTF-MP plus cholera toxin or dLT rats contained IgA antibody to GTF-MP. Low levels of fecal IgA antibody were detected in 3/6 intranasally immunized rats and 2/6 rats rectally immunized with GTF-MP alone. We then examined the extent to which salivary IgA antibody induced by the rectal route could be protective. At 25, 31 and 38 days of age, two groups of female Sprague-Dawley rats (13/group) were rectally immunized with GTF-MP and cholera toxin or with empty microparticles and cholera toxin (sham group). A third group was intranasally immunized with GTF-MP alone. After demonstrating salivary IgA responses to GTF in most GTF-immunized rats, all animals were infected with streptomycin-resistant Streptococcus sobrinus and placed on diet 2000. After 79 days of infection, total caries on molar surfaces were lower in both rectally (7.9 +/- 1.0) and intranasally (7.1 +/- 0.9; P < 0.0.03) immunized groups compared with the sham-immunized group (11.9 +/- 1.6). Smooth surface caries were significantly lower (P < 0.05) in both rectally and intranasally immunized groups. These results support the interconnectedness of the mucosal immune system and indicate that rectal immunization with GTF-MP, together with adjuvant, or intranasal immunization with GTF-MP alone, can induce protective levels of salivary antibody in rats.

Enhanced immunogenicity of a genetic chimeric protein consisting of two virulence antigens of Streptococcus mutans and protection against infection.

The saliva-binding region (SBR) of the cell surface antigen I/II (AgI/II) and the glucan-binding region (GLU) of the glucosyltransferase enzyme of Streptococcus mutans have been implicated in the initial adherence of S. mutans to saliva-coated tooth surfaces and the subsequent sucrose-dependent accumulation of S. mutans, respectively. Here, we describe the construction and characterization of a genetic chimeric protein consisting of the two virulence determinants SBR and GLU (SBR-GLU). The effectiveness of this construct in inducing mucosal and systemic immune responses to each virulence determinant following intranasal immunization was compared to that of each antigen alone or an equal mixture of SBR and GLU (SBR+GLU) in a mouse model. Furthermore, the ability of antibodies induced to SBR-GLU to protect against S. mutans infection was also investigated. Immunization of mice with the chimeric protein SBR-GLU resulted in significantly enhanced (P < 0.001) levels of serum immunoglobulin G (IgG) anti-SBR antibody activity compared to those in the SBR and SBR+GLU groups. The SBR-GLU-immunized mice also demonstrated a significant (P < 0.05) increase in salivary and vaginal IgA antibody responses to SBR and GLU. Analysis of the serum IgG subclass responses to SBR in mice immunized with SBR alone indicated a mixed IgG1 and IgG2a response. A preferential IgG1 response compared to an IgG2a anti-GLU response was induced in mice immunized with GLU alone. Similarly, a preferential IgG1 response was also induced to SBR when GLU was present in either a mixed or conjugated form. Finally, a significant reduction (P < 0.05) in S. mutans colonization was observed only in mice immunized with the SBR-GLU chimeric protein. Taken together, our results indicate that the chimeric protein SBR-GLU significantly enhanced mucosal immune responses to SBR and GLU and systemic immune responses to SBR. The ability of SBR-GLU to induce responses effective in protection against colonization of S. mutans suggests its potential as a vaccine antigen for dental caries.

Human T-cell responses to the glucosyltransferases of Streptococcus mutans.

We previously reported differential humoral responses to glucosyltransferases (GTFs), with significantly higher saliva and serum antibody levels to GtfD than to GtfB or GtfC. To test the hypothesis that cellular immune responses to these molecules also may differ, peripheral blood mononuclear cell (PBMC) and T-cell proliferative responses in young adults and children with distinct genetic backgrounds were determined using purified recombinant GtfC and GtfD. PBMCs from all of the volunteers responded to GtfC and -D, but responses were directed predominantly towards GtfD and were major histocompatibility class II antigen dependent. A predominant T-cell response to GtfD, over GtfC, was detectable at various antigen concentrations ranging from 1 to 20 microg/ml and correlated with the differential serum immunoglobulin G (IgG) and salivary IgA antibody responses to the GTFs. Therefore, in naturally sensitized humans, Streptococcus mutans GTFs stimulate differential humoral and cellular immune responses, with the secreted form of GtfD eliciting a stronger response than the cell wall-associated form of GtfC.

A vaccine against dental caries: an overview.

Dental caries continues to be a costly and prevalent oral disease. Research efforts towards developing a well tolerated and effective vaccine against dental caries were initiated following the demonstration of a specific bacterial aetiology for this disease. The cariogenic mutans streptococci are the principal bacteria causing this disease. Specific immune defence against these bacteria is provided mainly by secretory immunoglobulin (Ig) A antibodies present in saliva, which are generated by the common mucosal immune system. Progress in the development of a vaccine against dental caries has increased due to both advancements in molecular biology and our understanding of the mucosal immune system and mucosal vaccines. Advancements in molecular biology have facilitated the cloning and functional characterisation of virulence factors of the mutans streptococci, including the cell-surface fibrillar proteins, which mediate adherence to the tooth surface, and the glucosyltransferase enzymes, which synthesise adhesive glucans and allow microbial accumulation on the teeth. Current strategies for immunisation against dental caries are using these virulence factors as key antigens and incorporating them into novel mucosal vaccine systems and delivering them with or without adjuvants to mucosal IgA inductive sites. The most popular routes of mucosal immunisation are via the oral or nasal route. The mucosal immune system is functional in newborn infants, who develop salivary IgA antibodies as they become colonised by oral micro-organisms. Mucosal immunisation strategies result in the induction of salivary IgA antibody responses and pose fewer problems than parenteral injection of antigen. Therefore, mucosal immunisation of infants prior to the appearance of their first teeth may be a well tolerated and effective way to induce immunity against the colonisation of teeth by mutans streptococci and protection against subsequent dental caries. The purpose of this article is to provide an overview of the recent progress on the development of a vaccine against infection by Streptococcus mutans for the prevention of dental caries, with emphasis on the mucosal immune system and vaccine design.

Induction of secretory immunity with bioadhesive poly (D,L-lactide-co-glycolide) microparticles containing Streptococcus sobrinus glucosyltransferase.

The effect of mucosal delivery of Streptococcus sobrinus glucosyltransferase (GTF) in bioadhesive poly (D,L-lactide-co-glycolide) (PLGA) microparticles on induction of salivary IgA and serum IgG antibody responses was measured in Sprague-Dawley rats. Preparations of GTF/PLGA/gelatin microparticles, or PLGA/gelatin microparticles or GTF in alum, were administered four times at weekly intervals by intranasal or intragastric routes. Two subcutaneous injections of GTF in PLGA/gelatin microparticles or in alum were given to separate groups of rats. Significant elevations in salivary IgA antibody levels to S. sobrinus GTF were observed only in the groups immunized intranasally 28 days after immunizations were begun. Five of six rats given the GTF microparticles intranasally had positive salivary IgA antibody responses to GTF, and the mean salivary IgA antibody level of this group was 30-fold higher than any other mucosally or systemically immunized group. Salivary IgA responses in the GTF-microparticle group remained significantly higher than all other mucosally immunized groups for at least 10 weeks after the primary immunization. All rats in this group demonstrated aspects of anamnesis following a more limited secondary course of intranasal administration. Intranasal administration of GTF in microparticles also induced a serum IgG response to GTF in some rats. After secondary intranasal GTF microparticle administration, several rats had sustained serum IgG antibody levels that were within the range of sera from rats subcutaneously injected with GTF in microparticles or in alum. Thus intranasal delivery of GTF-containing bioadhesive microparticles induced the highest and longest lasting salivary immune response of any mucosal or systemic route or vehicle tested and could be expected to be a useful method for induction of mucosal immunity.

Circulating antibody secreting cell response to parenteral pneumococcal vaccines as an indicator of a salivary IgA antibody response

This study assessed the mucosal immune response in healthy adult volunteers immunized parenterally with either pneumococcal polysaccharide ( N = 8) or pneumococcal polysaccharide-protein conjugate ( N = 10) vaccine with an aim to evaluate the relevance of antibody secreting cell (ASC) response after parenteral vaccination. An ASC response to the four types of capsular polysaccharide tested was observed in all vaccinees 7–9 days after immunization. IgA was the predominant class in the ASC response, and IgG the next common, with very few IgM ASCs. The IgA IgG ratio in the ASC response was higher after immunization with the polysaccharide than the conjugate vaccine. Antibodies of the IgA class were frequently seen in the saliva already before immunization; especially to serotypes 14 and 19F. A twofold increase of the type specific secretory IgA antibodies in saliva was found in eight of the 16 instances in which the specific IgA ASC response was > 100 ASC per 10 6 cells and in only one of the 52 instances with fewer ASCs. We conclude that the ASC response in the peripheral blood is a useful parameter of the antibody response to pneumococcal vaccines and a good indicator of a secretory IgA response in the saliva.

Construction and oral immunogenicity of a Salmonella typhimurium strain expressing a streptococcal adhesin linked to the [formula omitted] subunits of cholera toxin

A mafor adhesin from the oral pathogen Streptococcus mutans has been shown to be mucosally immunogenic upon genetic fusion with the cholera toxin A2 B subunits. To take advantage of the ability of Salmonella typhimurium to deliver cloned antigens to the mucosal inductive sites that would obviate the need for antigen purification, we expressed this chimeric construct in an attenuated S. typhimurium strain under the control of bacteriophage T7 transcription. Residual expression of the temperature-regulated T7 RNA polymerase at 30°C allowed production of the chimeric protein at 2–3% of the total soluble protein, but it was increased five to six times following induction at 37°C. Oral administration of a single dose of 10 9 recombinant Salmonella to mice resulted in serum IgG and salivary IgA antibody responses to Salmonella, cholera toxin, and the streptococcal adhesin, which were generally enhanced after a booster immunization.

Controlled release microparticles for oral immunization

Microparticles with entrapped ovalbumin (OVA) were prepared using two different poly(lactide-co-glycolide) polymers (Resomers RG 506 and 755) with different rates of degradation and were orally administered to two groups of mice. Both groups showed enhanced serum IgG and salivary IgA antibody responses in comparison to a group of mice immunized with soluble OVA. but the level of responses induced depended on the polymer. The more rapidly degrading polymer (RG 506) was most effective for the induction of high levels of salivary IgA antibodies, while the more slowly degrading polymer (RG 755) was most effective for the induction of serum IgG antibodies.