清野 宏

The epitopes for OVA323-339-specific CD4(+)T cells from OVA23-3 food allergy model and DO11.10 tolerant induction model mice were analyzed. We found that OVA23-3 CD4(+)T cells recognized the N-terminal region, showing strong proliferation and the Th2-phenotype, and that DO11.10 CD4(+)T cells recognized the C-terminal region, showing milder proliferation and a Th1-skewed response. These differences may regulate the responses of those mice to OVA-feeding, inflammation and tolerance.

Influenza HA split vaccine is widely administered to children and adults worldwide. However, its limited efficacy and weak potential to control the next influenza pandemic has recently been emphasized and has raised serious concerns. These circumstances led the Japanese Society for Vaccinology to organize this symposium to discuss the next generation of influenza vaccine which should be more efficacious and much safer. The symposium covered data assessment of the newly developed H5N1 vaccine, adjuvant development for influenza vaccine, the future threat of H5N1 influenza, measures for its control, and the recent development of a mucosal vaccine.© 2012.

Dietary compounds as well as commensal microbiota contribute to the generation of a unique gut environment. In this study, we report that dietary folic acid (FA) is required for the maintenance of Foxp3(+) regulatory T cells (Tregs) in the colon. Deficiency of FA in the diet resulted in marked reduction of Foxp3(+) Tregs selectively in the colon. Blockade of folate receptor 4 and treatment with methotrexate, which inhibits folate metabolic pathways, decreased colonic Foxp3(+) Tregs. Compared with splenic Tregs, colonic Tregs were more activated to proliferate vigorously and were highly sensitive to apoptosis. In colonic Tregs derived from mice fed with a FA-deficient diet, expression of anti-apoptotic molecules Bcl-2 and Bcl-xL was severely decreased. A general reduction of peripheral Tregs was induced by a neutralizing Ab against IL-2, but a further decrease by additional FA deficiency was observed exclusively in the colon. Mice fed with an FA-deficient diet exhibited higher susceptibility to intestinal inflammation. These findings reveal the previously unappreciated role of dietary FA in promotion of survival of Foxp3(+) Tregs that are in a highly activated state in the colon. The Journal of Immunology, 2012, 189: 2869-2878.

The mammalian intestinal tract is colonized by trillions of beneficial commensal bacteria that are anatomically restricted to specific niches. However, the mechanisms that regulate anatomical containment remain unclear. Here, we show that interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) are present in intestinal tissues of healthy mammals. Depletion of ILCs resulted in peripheral dissemination of commensal bacteria and systemic inflammation, which was prevented by administration of IL-22. Disseminating bacteria were identified as Alcaligenes species originating from host lymphoid tissues. Alcaligenes was sufficient to promote systemic inflammation after ILC depletion in mice, and Alcaligenes-specific systemic immune responses were associated with Crohn's disease and progressive hepatitis C virus infection in patients. Collectively, these data indicate that ILCs regulate selective containment of lymphoid-resident bacteria to prevent systemic inflammation associated with chronic diseases.

Specific intestinal microbiota has been shown to induce Foxp3+ regulatory T cell development. However, it remains unclear how development of another regulatory T cell subset, Tr1 cells, is regulated in the intestine. Here, we analyzed the role of two probiotic strains of intestinal bacteria, Lactobacillus casei and Bifidobacterium breve in T cell development in the intestine. B. breve, but not L. casei, induced development of IL-10-producing Tr1 cells that express cMaf, IL-21, and Ahr in the large intestine. Intestinal CD103+ dendritic cells (DCs) mediated B. breve-induced development of IL-10-producing T cells. CD103+ DCs from Il10-/-, Tlr2-/-, and Myd88-/- mice showed defective B. breve-induced Tr1 cell development. B. breve-treated CD103+ DCs failed to induce IL-10 production from co-cultured Il27ra-/- T cells. B. breve treatment of Tlr2-/- mice did not increase IL-10-producing T cells in the colonic lamina propria. Thus, B. breve activates intestinal CD103+ DCs to produce IL-10 and IL-27 via the TLR2/MyD88 pathway thereby inducing IL-10-producing Tr1 cells in the large intestine. Oral B. breve administration ameliorated colitis in immunocompromised mice given naïve CD4+ T cells from wild-type mice, but not Il10-/- mice. These findings demonstrate that B. breve prevents intestinal inflammation through the induction of intestinal IL-10-producing Tr1 cells. © 2012 Jeon et al.

Background Nasopharynx-associated lymphoid tissue (NALT) serves as an important inductive site for mucosal immunity in the upper respiratory tract. Despite its importance in the mucosal immune system, little is known regarding the role of NALT in airway allergic immune responses. We aimed to elucidate the role of NALT in the induction of upper airway allergic responses in a mouse model. Methods Inhibitor of DNA binding/differentiation 2 (Id2)-/- and Id2+/- mice was exposed to the ovalbumin (OVA)-induced allergic rhinitis model, because the former resulted in the NALT deficiency. The allergic parameters, such as allergic symptoms, serum OVA-specific immunoglobulin E (IgE) levels, eosinophil infiltration, and cytokine profiles in the nasal mucosa, were compared between Id2-/- and Id2+/- groups. Results NALT-null, Id2-/- mice displayed significantly lower allergic responses compared with Id2+/- mice, as demonstrated by lower levels of allergic symptoms, serum OVA-specific IgE, eosinophilic infiltration, and local Th2 cytokine transcriptions. To determine which of two factors, that is, the absence of NALT or the alteration of immunocompetent cell populations caused by the Id2 deficiency, has a larger effect on the attenuated allergic immune responses in Id2-/- mice, lethally irradiated Id2-/- mice were engrafted with C57BL/6 wild-type bone marrow cells and showed still significantly lower allergic immune responses compared with equally treated Id2+/- mice. In addition, IgE class switch recombination-associated molecules, such as μ immunoglobulin heavy-chain germline gene transcript, μ mRNA, and activation-induced cytidine deaminase mRNA, were detected in NALT from OVA-sensitized wild-type mice. Conclusion These results show the critical role of NALT for the induction of allergic responses in the upper airway at least in part by means of class switching to IgE in situ. © 2012 John Wiley &amp Sons A/S.

In recent years, advances in the humanized mouse system have led to significantly increased levels of human hematopoietic stem cell (HSC) engraftment. The remaining limitations in human HSC engraftment and function include lymphoid-skewed differentiation and inefficient myeloid development in the recipients. Limited human HSC function may partially be attributed to the inability of the host mouse microenvironment to provide sufficient support to human hematopoiesis. To address this problem, we created membrane-bound human stem cell factor (SCF)/KIT ligand (KL)-expressing NOD/SCID/IL2rgKO (hSCF Tg NSG) mice. hSCF Tg NSG recipients of human HSCs showed higher levels of both human CD45(+) cell engraftment and human CD45(+) CD33(+) myeloid development compared with NSG recipients. Expression of hSCF/hKL accelerated the differentiation of the human granulocyte lineage cells in the recipient bone marrow. Human mast cells were identified in bone marrow, spleen, and gastrointestinal tissues of the hSCF Tg NSG recipients. This novel in vivo humanized mouse model demonstrates the essential role of membrane-bound hSCF in human myeloid development. Moreover, the hSCF Tg NSG humanized recipients may facilitate investigation of in vivo differentiation, migration, function, and pathology of human mast cells. (Blood. 2012; 119(12): 2768-2777)

It has been shown that dietary materials are involved in immune regulation in the intestine. Lipids mediate immune regulation through a complex metabolic network that produces many kinds of lipid mediators. Sphingosine-1-phosphate (S1P) is a lipid mediator that controls cell trafficking and activation. In this review, we focus on the immunological functions of S1P in the regulation of intestinal immune responses such as immunoglobulin A production and unique T cell trafficking, and its role in the development of intestinal immune diseases such as food allergies and intestinal inflammation, and also discuss the relationship between dietary materials and S1P metabolism.

Dietary factors regulate immunological function, but the underlying mechanisms remain elusive. Here we show that vitamin B9 is a survival factor for regulatory T (Treg) cells expressing high levels of vitamin B9 receptor (folate receptor 4). In vitamin B9-reduced condition in vitro, Treg cells could be differentiated from native T cells but failed to survive. The impaired survival of Treg cells was associated with decreased expression of anti-apoptotic Bcl2 and independent of IL-2. In vivo depletion of dietary vitamin B9 resulted in the reduction of Treg cells in the small intestine, a site for the absorption of dietary vitamin B9. These findings provide a new link between diet and the immune system, which could maintain the immunological homeostasis in the intestine.

Secretory-immunoglobulin A (S-IgA) plays an important role in immunological defense in the intestine. It has been known for a long time that microbial stimulation is required for the development and maintenance of intestinal IgA production. Recent advances in genomic technology have made it possible to detect uncultivable commensal bacteria in the intestine and identify key bacteria in the regulation of innate and acquired mucosal immune responses. In this review, we focus on the immunological function of Peyer's patches (PPs), a major gut-associated lymphoid tissue, in the induction of intestinal IgA responses and the unique immunological interaction of PPs with commensal bacteria, especially Alcaligenes, a unique indigenous bacteria habituating inside PPs.

近年，シークエンス技術や質量分析技術が発展するにつれて，腸内フローラのメタゲノム解析やメタボローム解析などの網羅的解析が可能となり，腸内フローラに関する研究が急速に拡大している．なかでも，腸内フローラと宿主粘膜免疫システムのクロストークについての研究の進展はめざましく，これまでに分泌型IgAに代表される免疫分子が腸内フローラならびに宿主腸管の恒常性維持に寄与していることが明らかとなってきた．一方，腸内フローラは「正」と「負」の免疫応答を主導するT細胞を誘導し，腸管において生理的炎症状態という生体にとって有用な環境を創出することで，宿主粘膜免疫の構築と維持に重要な役割を果たしている．この生理的炎症状態は，腸内フローラと粘膜免疫のクロストークによって巧妙に制御されているものの，この恒常性が崩れると炎症性腸疾患をはじめとする免疫疾患発症へと繋がる．腸内フローラ，および粘膜免疫の恒常性維持機構を明らかにすることは，これら疾患の新規治療法開発の基盤となる重要な情報を提供するのみならず，次世代型ワクチンとして期待されている経口ワクチンに代表される粘膜ワクチン開発に向けても貴重な開発戦略基盤を提供することができるであろう．<br>

Scope: Oral immunotherapy (OIT) involving continuous oral administration of allergenic foods has gained attention as a therapy for food allergies. To study the influence of oral administration of allergenic foods on gastrointestinal symptoms including inflammation, we established a mouse model of food-induced intestinal allergy. Methods and results: BALB/c mice were fed an egg white (EW) diet containing ovalbumin (OVA, a major EW allergen) after intraperitoneal sensitisation with OVA and Alum. The mice on the EW diet for one wk presented gastrointestinal symptoms (i.e. weight loss and soft stools) and inflammation in the small intestines (i.e. duodenum, jejunum and ileum). Further continuous EW diet resolved the weight loss but not the soft stools. Splenic CD4(+) T-cells of EW diet-fed mice on the continuous diet showed less proliferation and cytokine production compared with those of control mice, suggesting tolerance induction by the diet. The continuous EW diet reduced levels of OVA-specific IgE antibodies, but significantly aggravated the inflammation in the jejunum. Conclusion: Our mouse model would be useful to investigate inflammatory and regulatory mechanisms in food-induced intestinal allergies. Our results suggest potential gastrointestinal inflammation in patients undergoing OIT as continuous administration of allergenic foods, even though the therapy may induce clinical tolerance.

Selective autophagy of bacterial pathogens represents a host innate immune mechanism. Selective autophagy has been characterized on the basis of distinct cargo receptors but the mechanisms by which different cargo receptors are targeted for autophagic degradation remain unclear. In this study we identified a highly conserved Tectonin domain-containing protein, Tecpr1, as an Atg5 binding partner that colocalized with Atg5 at Shigella-containing phagophores. Tecpr1 activity is necessary for efficient autophagic targeting of bacteria, but has no effect on rapamycin- or starvation-induced canonical autophagy. Tecpr1 interacts with WIPI-2, a yeast Atg18 homolog and PI(3)P-interacting protein required for phagophore formation, and they colocalize to phagophores. Although Tecpr1-deficient mice appear normal, Tecpr1-deficient MEFs were defective for selective autophagy and supported increased intracellular multiplication of Shigella. Further, depolarized mitochondria and misfolded protein aggregates accumulated in the Tecpr1-knockout MEFs. Thus, we identify a Tecpr1-dependent pathway as important in targeting bacterial pathogens for selective autophagy.

Quantitative and qualitative aspects of commensal bacteria determine the active and quiescent status of host immunity. In a recent Science paper, Atarashi et al. (2011) identify Clostridium clusters IV and XlVa as indigenous commensal bacteria that induce regulatory T cells for the creation and maintenance of immunological homeostasis.

Mucosa-associated lymphoid tissues (MALT) play a critical role as inductive sites for the initiation of antigen-specific protective immunity against pathogens penetrating the mucus membranes. Nasopharynx-associated lymphoid tissue (NALT), situated at the bottom of the rodent nasal cavity, is thought to be an important site for the induction of antigen-specific immune response to inhaled antigens. In addition, we have recently shown that tear duct-associated lymphoid tissue (TALT), present in the murine tear duct bridging the ocular and nasal cavities, is involved in the induction and regulation of both nasal and ocular immunity. Interestingly, cellular requirements for the organogenesis of NALT and TALT are quite different from those of other MALT (e.g. Peyer's patches; PPs) and peripheral lymphoid tissues. Moreover, mucosal imprinting molecules of NALT and TALT inducer cells are totally independent of currently known chemokines and adhesion molecules in PPs and lymph nodes, such as the CXCR5-CXCL13, alpha 4 beta 1 integrin-vascular cell adhesion molecule-1 (VCAM1), and CCR9-CCL25 axes. NALT and TALI lymphocytes are also independent of these tissue-specific migration molecules. Together with already-characterized conjunctiva-associated lymphoid tissue (CALT), which has been demonstrated to play a critical role in ocular defense, the MALT associated with the head region seems to be coordinately organizing the unique craniofacial mucosal immune system of the ocular, nasal, oral-pharynx mucus membranes. Clarification of the immunological network of this unique craniofacial immune system will facilitate the development of a safe and effective mucosal vaccine against respiratory and ocular infections. Copyright (C) 2011 S. Karger AG, Basel

In mice implanted with an osmotic pump filled with the superantigen (SAG) staphylococcal enterotoxin A (SEA), the V beta 3(+)CD4(+) T cells exhibited a high level of expansion whereas the V beta 11(+)CD4(+) T cells exhibited a mild level of expansion. In contrast, in mice implanted with an osmotic pump filled with SE-like type P (SElP, 78.1% homologous with SEA), the V beta 11(+)CD4(+) T cells exhibited a high level of expansion while the V beta 3(+)CD4(+) T cells exhibited a low level of expansion, suggesting that the level of the SAG-induced response is determined by the affinities between the TCR V beta molecules and SAG. Analyses using several hybrids of SEA and SElP showed that residue 206 of SEA determines the response levels of V beta 3(+)CD4(+) and V beta 11(+)CD4(+) T cells both in vitro and in vivo. Analyses using the above-mentioned hybrids showed that the binding affinities between SEA and the V beta 3/V beta 11 beta chains and between SEA-MHC class II-molecule complex and V beta 3(+)/V beta 11(+) CD4(+) T cells determines the response levels of the SAG-reactive T cells both in vitro and in vivo.

Antigen uptake has been shown to occur in the teleost intestine, but so far, limited information is available on the distribution and nature of cells involved in the process, and M cells, known for their antigen-sampling abilities in mammals, have not been identified. Here, different intestinal segments from salmonid fish were exposed to gold-BSA to identify antigen-sampling cells. Sections from exposed intestine were examined by light and electron microscopy. Uptake of gold-BSA was restricted to very few dendritic-like cells and to a limited number of epithelial cells located in the mucosal folds in the second segment of the mid-intestine. Gold-positive epithelial cells displayed diverging and electron-dense microvilli with channels intruding into the cytoplasm. A lectin binding experiment demonstrated the presence of cells with mammalian M-cell characteristics in the identical regions. As the identified epithelial cells shared some morphological similarities with immature mammalian M cells, this phenotype may represent evolutionary early antigen-sampling enterocytes. (C) 2010 Elsevier Ltd. All rights reserved.

Enteropathy-associated T cell lymphoma is a severe complication of celiac disease (CD). One mechanism suggested to underlie its development is chronic exposure of intraepithelial lymphocytes (IELs) to potent antiapoptotic signals initiated by IL-15, a cytokine overexpressed in the enterocytes of individuals with CD. However, the signaling pathway by which IL-15 transmits these antiapoptotic signals has not been firmly established. Here we show that the survival signals delivered by IL-15 to freshly isolated human IELs and to human IEL cell lines derived from CD patients with type II refractory CD (RCDII) - a clinicopathological entity considered an intermediary step between CD and enteropathy-associated T cell lymphoma - depend on the antiapoptotic factors Bcl-2 and/or Bcl-xL. The signals also required IL-15R beta, Jak3, and STAT5, but were independent of PI3K, ERK, and STAT3. Consistent with these data, IELs from patients with active CD and RCDII contained increased amounts of Bcl-xL, phospho-Jak3, and phospho-STAT5. Furthermore, incubation of patient duodenal biopsies with a fully humanized human IL-15-specific Ab effectively blocked Jak3 and STAT5 phosphorylation. In addition, treatment with this Ab induced IEL apoptosis and wiped out the massive IEL accumulation in mice overexpressing human IL-15 in their gut epithelium. Together, our results delineate the IL-15-driven survival pathway in human IELs and demonstrate that IL-15 and its downstream effectors are meaningful therapeutic targets in RCDII.

Cholera and enterotoxigenic Escherichia coli (ETEC) are among the most common causes of acute infantile gastroenteritis globally. We previously developed a rice-based vaccine that expressed cholera toxin B subunit (MucoRice-CTB) and had the advantages of being cold chain-free and providing protection against cholera toxin (CT)-induced diarrhea. To advance the development of MucoRice-CTB for human clinical application, we investigated whether the CTB-specific secretory IgA (SIgA) induced by MucoRice-CTB gives longstanding protection against diarrhea induced by Vibrio cholerae and heat-labile enterotoxin (LT)-producing ETEC (LT-ETEC) in mice. Oral immunization with MucoRice-CTB stored at room temperature for more than 3 y provided effective SIgA-mediated protection against CT- or LT-induced diarrhea, but the protection was impaired in polymeric Ig receptor-deficient mice lacking SIgA. The vaccine gave longstanding protection against CT- or LT-induced diarrhea (for &gt;= 6 months after primary immunization), and a single booster immunization extended the duration of protective immunity by at least 4 months. Furthermore, MucoRice-CTB vaccination prevented diarrhea in the event of V. cholerae and LT-ETEC challenges. Thus, MucoRice-CTB is an effective long-term cold chain-free oral vaccine that induces CTB-specific SIgA-mediated longstanding protection against V. cholerae or LT-ETEC -induced diarrhea.

The gastrointestinal immune system is a major component of the mucosal barrier, which maintains an immunologic homeostasis between the host and the harsh environment of the gut. This homeostasis is achieved by immunologic quiescence, and its dysregulation is thought to result from the development of immune diseases such as food allergies. Recent findings have revealed versatile pathways in the development of intestinal allergies to certain food antigens. In this review, we summarize the regulatory and quiescence mechanisms in the gut immune system and describe aberrant interactions between the host immune system and the gut environment in the development of food allergies.

Immunoglobulin A (IgA) is the body's predominant antibody isotype, and the bulk of the body's IgA-producing cells reside in various mucosal and exocrine tissues. Production of IgA at mucosal surfaces is strictly regulated through coordinated communication among mucosal B and T cells, mucosal dendritic cells (DCs), and epithelial cells. Although organized lymphoid tissues such as Peyer's patches (PP) have long been recognized as key sources of IgA plasma cells at mucosal surfaces, IgA-mediated mucosal immune response is maintained even in PP-null conditions. Mucosal DCs likely are specialized to provide help to B cells to promote IgA-producing plasma cells. Intriguingly, induction of the proliferation of microbiota-specific IgA⁺ B cells is independent of T helper activity but may depend on lamina propria DCs expressing iNOS, CX3CR1, and TLR5.<BR>In the quest to develop an oral vaccine to boost mucosal immunity, rice was genetically engineered to express the B subunit of cholera toxin (CT-B). The recombinant CT-B that accumulates in the protein bodies of rice is resistant to the harsh gastrointestinal environment, and immunization of mice with the vaccine provoked a protective mucosal IgA response against CT. Furthermore, the vaccine is stable and maintains immunogenicity at room temperature for at least 24 months. Because they are easy to administer and requires neither refrigeration nor needles, rice-based mucosal vaccines are highly practical for global immunization against infectious diseases.

Nanotechnology is an innovative method of freely controlling nanometre-sized materials1. Recent outbreaks of mucosal infectious diseases have increased the demands for development of mucosal vaccines because they induce both systemic and mucosal antigen-specific immune responses 2. Here we developed an intranasal vaccine-delivery system with a nanometre-sized hydrogel ('nanogel-™) consisting of a cationic type of cholesteryl-group-bearing pullulan (cCHP). A non-toxic subunit fragment of Clostridium botulinum type-A neurotoxin BoHc/A administered intranasally with cCHP nanogel (cCHP-BoHc/A) continuously adhered to the nasal epithelium and was effectively taken up by mucosal dendritic cells after its release from the cCHP nanogel. Vigorous botulinum-neurotoxin-A-neutralizing serum IgG and secretory IgA antibody responses were induced without co-administration of mucosal adjuvant. Importantly, intranasally administered cCHP-BoHc/A did not accumulate in the olfactory bulbs or brain. Moreover, intranasally immunized tetanus toxoid with cCHP nanogel induced strong tetanus-toxoid-specific systemic and mucosal immune responses. These results indicate that cCHP nanogel can be used as a universal protein-based antigen-delivery vehicle for adjuvant-free intranasal vaccination. © 2010 Macmillan Publishers Limited. All rights reserved.

Interleukin (IL)-15 interacts with components of the IL-2 receptor (R) and exhibits T cell-stimulating activity similar to that of IL-2. In addition, IL-15 is widely expressed in many cell types and tissues, including the central nervous system. We provide evidence of a novel role of IL-15 in olfactory neurogenesis. Both IL-15 and IL-15Rα were expressed in neuronal precursor cells of the developing olfactory epithelium in mice. Adult IL-15Rα knockout mice had fewer mature olfactory neurons and proliferating cells than wild-type. Our results suggest that IL-15 plays an important role in regulating cell proliferation in olfactory neurogenesis. © 2009 Japanese Teratology Society.

Microfold cells (M cells) are specialized epithelial cells situated over Peyer&apos;s patches (PP) and other organized mucosal lymphoid tissues that transport commensal bacteria and other particulate Ags into intraepithelial pockets accessed by APCs. The TNF superfamily member receptor activator of NF-kappa B ligand (RANKL) is selectively expressed by subepithelial stromal cells in PP domes. We found that RANKL null mice have &lt;2% of wild-type levels of PP M cells and markedly diminished uptake of 200 nm diameter fluorescent beads. Ab-mediated neutralization of RANKL in adult wild-type mice also eliminated most PP M cells. The M cell deficit in RANKL null mice was corrected by systemic administration of exogenous RANKL. Treatment with RANKL also induced the differentiation of villous M cells on all small intestinal villi with the capacity for avid uptake of Salmonella and Yersinia organisms and fluorescent beads. The RANK receptor for RANKL is expressed by epithelial cells throughout the small intestine. We conclude that availability of RANKL is the critical factor controlling the differentiation of M cells from RANK-expressing intestinal epithelial precursor cells. The Journal of Immunology, 2009, 183: 5738-5747.

The respiratory and gastrointestinal tracts are equipped with a unique mucosal immune system that contributes to immunosurveillance and immunological homeostasis in the harsh environments of the mucosal surfaces. While the respiratory and gastrointestinal immune systems share common mucosa-associated immunological features, they also show distinctive immunological phenotypes, functions, and developmental pathways. We describe here the common immunological features of the respiratory and gastrointestinal immune systems and their application to the potential development of mucosal immune therapy.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) regulates intestinal immunological homeostasis. However, precise expression patterns of CEACAM1 isoforms remain poorly understood in the intestinal epithelia. Focusing on the small intestinal epithelium of BALB/c mice, we identified three novel splice variants encoding CEACAM1a-2, -2C1, and -4C1 by RT-PCR. CEACAM1a-2, -2C1, and -4C1 demonstrated secretory properties by transfection experiments in vitro. Among them, CEACAM1a-4C1 was the major secreted isoform in vivo due to the soluble/secreted CEACAM1a with a frameshift sequence in the C-terminus, specific for CEACAM1a-2C1 and -4C1. CEACAM1a-4C1 was capable of binding murine hepatitis virus (MHV) and was detected at approximately 120 kDa in the small intestinal secretions. Neutralizing effects of the soluble CEACAM1a on MHV infectivity in vitro were demonstrated by using recombinant CEACAM1a-4C1. Our data suggest an intrinsic mechanism operated by free CEACAM1 for surveillance of pathogens and maintenance of homeostasis in the intestine. © 2009 Elsevier Inc. All rights reserved.

Purpose of review Oral immunization with vaccines against intestinal infectious diseases has been extensively explored for several decades. Despite the immunologic and economic rationale behind oral immunization, only a few mucosal vaccines are available for the prevention of mucosal infections. Here we summarize the current status of such at, vaccines with a focus on intestinal infectious diseases, describe alternative approaches, and analyze advantages and difficulties encountered with a broad implementation of these vaccines. Recent findings Due to the limited absorption from the intestinal tract and sensitivity to degradation, oral vaccines composed of killed bacteria and viruses or antigens isolated from infectious agents have not been successful. New, live-attenuated bacterial and viral or edible plant-derived vaccines, however, have been recently introduced for this purpose. Furthermore, systemic immunization with vaccines composed of bacterial polysaccharides chemically coupled to suitable protein carriers induces high levels of IgG antibodies, which may provide immunity toward Salmonella typhi, Shigella, and Escherichia coli. Summary Further improvements in antigen-delivery systems, the development of adjuvants that are safe for mucosal application in humans, use of live-attenuated vaccines and microbial vectors, and production of certain vaccines in plant expression systems are likely to contribute to the broader use of oral vaccines in the future.

White spot syndrome virus (WSSV) disease is a major threat to shrimp culture worldwide. Here, we assessed the efficacy of the oral administration of purified recombinant VP28, an envelope protein of WSSV, expressed in a Gram-positive bacterium, Brevibacillus brevis, in providing protection in shrimp, Penaeus japonicus, upon challenge with WSSV. Juvenile shrimp (2-3 g in body weight) fed with pellets containing purified recombinant VP28 (50 μg/shrimp) for 2 weeks showed significantly higher survival rates than control groups when challenged with the virus at 3 days after the last day of feeding. However, when shrimp were challenged 2 weeks after the last day of feeding, survival rates decreased (33.4% and 24.93%, respectively). Survival rate was dose-dependent, increasing from 60.7 to 80.3% as the dose increased from 1 to 50 μg/shrimp. At a dose of 50 μg/shrimp, the recombinant protein provided protection as soon as 1 day after feeding (72.5% survival). Similar results were obtained with larger-sized shrimp. These results show that recombinant VP28 expressed in a Gram-positive bacterium is a potential oral vaccine against WSSV. © 2008 Elsevier Ltd. All rights reserved.

Viral glycoproteins interact with cell-surface receptors to mediate virus entry and innate immune system activation. We found that a soluble recombinant infectious hematopoietic necrosis virus G-protein (rIHNV-G) stimulated an early innate immune response mediated by proinflammatory cytokines, IFN1 and IFN-γ in rainbow trout (Oncorhynchus mykiss) fry. Expression of both IFN1 and IFN-γ mRNA transcripts was an early event and was rIHNV-G dose-dependent. In addition, preliminary evidence revealed that the innate immune response induced by rIHNV-G protein could protect rainbow trout fry from a subsequent IHNV virus challenge. Finally, the binding and distribution of FITC-rIHNV-G protein on rainbow trout spleen and head kidney leukocytes resemble morphological changes which occur on the cell membrane during antigen-receptor interaction including membrane reorganization, patching, polarization and capping. Thus a soluble nonglycosylated rIHNV-G protein could mediate the activation of rainbow trout leukocytes, with concomitant production of proinflammatory cytokines and IFNs. © 2008 Elsevier Ltd. All rights reserved.