旋毛虫Ts87抗原的免疫学特性及保护性的初步研究

应用Western btot和ELISA方法对纯化的重组蛋白PET—28a( )／Ts87进行免疫学特性鉴定及保护性研究。Western blot和ELISA结果显示,Ts87抗原可被人工感染旋毛虫的兔血清、病猪血清、病人血清及抗Ts87的兔血清所识别。Ts87抗原免疫BABL/c小鼠,较对照组减虫率为29％,说明Ts87抗原可作为旋毛虫免疫诊断和疫苗的候选抗原。     

Herpes simplex virus vectors elicit durable immune responses in the presence of preexisting host immunity

Herpes simplex virus (HSV) recombinants are being developed as vaccine vectors for the expression of heterologous antigens. There is concern, however, that preexisting HSV immunity may decrease their effectiveness. We have addressed this issue in an animal model. Immunized mice were inoculated with a replication-defective HSV-1 vector that expressed the Escherichia coli beta-galactosidase protein as a model antigen. We assessed vector efficacy by analyzing the immunoglobulin G (IgG) antibody response and cellular proliferative response directed against beta-galactosidase. We report that the ability of the vector to induce antibody or proliferative responses was not diminished by preexisting immunity to HSV. Of further note, the anti-HSV and anti-beta-galactosidase IgG responses following vector administration were extremely durable in both immunized and naive mice. These results indicate that the ability of a replication-defective HSV-derived vaccine vector to elicit long-lived immune responses in mice is not impaired by prior HSV exposure.     

Approaches to augmenting the immunogenicity of the ganglioside GM2 in mice: purified GM2 is superior to whole cells

The gangliosides GM2, GD2, and GD3 are differentiation antigens largely restricted to cells of neuroectodermal origin. They are expressed on most melanomas, astrocytomas, and neuroblastomas and have been shown to function as effective targets for monoclonal antibodies. In previous studies, we have immunized melanoma patients and mice with a series of melanoma cell vaccines containing these antigens, but have observed only occasional antibody responses. We report here the results of experiments in which an irradiated whole cell vaccine shown previously to be optimal was compared with a series of vaccines containing purified GM2. Mice were pretreated with low dose cyclophosphamide (Cy), or not, and were immunized twice with syngeneic melanoma cells (JB-RH) known to contain 60 micrograms of GM2 or with vaccines containing 50 micrograms of purified GM2. Serum was obtained at regular intervals and was tested by immune adherence, complement dependent cytotoxicity, and protein A assays on the JB-RH cell line. The whole cell vaccine, GM2 alone, GM2 incorporated into complete Freund's adjuvant, and GM2 attached to E. coli were all minimally immunogenic. GM2 attached to Salmonella minnesota or BCG, and GM2 attached to certain liposome preparations containing monophosphoryl lipid A, were found to be moderately immunogenic. GM2 attached to the R595 mutant of Salmonella minnesota was found to be significantly more immunogenic. Pretreatment with Cy significantly increased the immunogenicity of this vaccine. The specificities of selected sera were tested in inhibition assays and were limited to GM2. Antibodies produced after immunization were generally exclusively IgM and mediated potent complement-dependent cytotoxicity on JB-RH cells. These results identify R595 as the most effective adjuvant tested for augmenting the immunogenicity of GM2 and show that with regard to antibody production, purified tumor antigen presented optimally can be more immunogenic than optimally presented whole tumor cells containing the same amount of antigen.     

嗜肺巴氏杆菌外膜蛋白和脂多糖抗原在血清学诊断中的意义

目的评价嗜肺巴氏杆菌外膜蛋白(OMP)和脂多糖(LPs)作为血清学诊断抗原的敏感性和特异性.方法用OMP、LPS和全菌(WC)作为Western blot和ELISA的诊断抗原检测自然感染和实验感染嗜肺巴氏杆菌小鼠相应的IgG抗体滴度,同时测定3种抗原与实验动物常见致病菌的交叉反应.结果与嗜肺巴氏杆菌自然感染和实验感染小鼠血清的ELISA反应中,不同时期,LPS作为诊断抗原时血清抗体阳性率最高,WC次之,OMP最低.自然感染小鼠群中,出生4周LPS抗体阳性率即可达80%,而同期的WC和OMP仅为25%和20%,故LPS敏感性最高.与实验动物常见致病菌免疫血清和阴性种鼠血清的ELISA反应中,WC抗原表现出较高的吸光度(A)值,经Western blot证实,其反应为非特异性反应,LPS抗原特异性最强,OMP抗原次之.结论混合多株具有型或种特异性的OMP或LPS作为ELISA的诊断抗原,无论从特异性和敏感性上均高于全菌抗原.     

Immunization of mice with melanoma cells transfected to secrete the superantigen, staphylococcal enterotoxin A

Immunization of mice with a melanoma vaccine coupled with staphylococcal enterotoxin A (SEA) inhibits the growth of primary melanoma tumors in mice. We have now successfully transfected B16 cells with the sea gene and have immunized C57BL/6 mice subcutaneously once per week for 4 weeks prior to tumor challenge with vaccines of irradiated B16 cells or, 4 weeks following tumor challenge of naïve mice with B16 cells, with irradiated B16 cells transfected with the sea gene. Primary tumor growth following both types of treatments was inhibited significantly. To characterize immune responses to these immunogens, we examined the production of antibodies to the B700 melanoma antigen, the stimulation of endogenous IL-2 production, the expression of CD4, CD8, Vβ and CD25 T cell markers, and the induction of NK activity. At 4 weeks following immunization of mice, there was a significant increase (P<0.05) in levels of interleukin-2 production by splenocytes from mice immunized with SEA-secreting B16 cells or with the parental B16 cells, compared to controls. Levels of antibodies to the B700 melanoma antigen were also significantly higher in mice immunized with the SEA-secreting B16 cells, as was expression of CD4, CD8, CD25 and Vβ T cell antigens, particularly CD4. Natural killer cell activity (at various E:T ratios) was tenfold higher in splenocytes of mice immunized with SEA-secreting B16 cells, and fivefold higher in mice immunized with the parental B16 cells, compared to controls.?These data confirm the possibility of using irradiated murine melanoma cells transfected to secrete SEA in vaccines targeted at preventing the development and growth of melanoma.     

An enzyme-linked immunosorbent assay for detection of chronic subclinical Pasteurella pneumotropica infection in mice.

Serum samples from seventy-five, 3- to 12-week-old and 16 retired breeder male Swiss mice from a conventional colony with enzootic chronic subclinical Pasteurella pneumotropica infection were tested by enzyme-linked immunosorbent assay (ELISA) and Western blots for IgG antibodies to whole cell (WC) and lipooligosaccharide (LOS) antigens of P. pneumotropica. In 3- to 12-week-old mice, serum antibody levels to LOS exceeded those to the WC preparation. Western blots of sera from mice in this age group substantiated that a major component of the early IgG antibody response was directed against LOS antigens. Higher antibody levels to both antigen preparations in 3-week-old mice compared to mice 4 and 6 weeks old were interpreted as reflecting a decline in antibodies acquired from the dam. Active immunity indicative of infection was first detected at 8 weeks of age. Serum samples from retired breeder mice (28 weeks of age) also had substantial antibody titers to LOS but, in contrast to sera from mice in the younger age groups, retired breeders had significantly greater IgG reactivity to WC preparations than to LOS antigens. The superior specificity of the LOS antigen compared to the WC preparation in the ELISA was demonstrated by testing serum samples from retired breeder mice against WC and LOS antigens from P. ureae, P. multocida, and P. hemolytica. The reactivity of IgG against LOS antigens from these organisms was negligible, whereas substantial titers were evident to WC antigens. This ELISA, using LOS preparations as antigen, is a useful serologic assay for the detection of subclinical P. pneumotropica infection in mice.     

猪丹毒丝菌天然SpaA和重组SpaA-N免疫保护效果的评价

【目的】本试验以小鼠为动物模型,评估了猪丹毒丝菌重组表面保护性抗原A的N端保护区域(rSpaA-N)和天然SpaA的免疫保护效果。【方法】将猪丹毒丝菌C43311株SpaA-N以可溶形式表达在大肠杆菌BL21中,用GST Bind Resin纯化试剂盒纯化rSpaA-N,采用电洗脱法从猪丹毒丝菌C43311株NaOH提取抗原中纯化天然SpaA,将rSpaA-N、天然SpaA和NaOH提取抗原制成亚单位疫苗,同时设GST及生理盐水对照组,间隔2周分3次皮下免疫小鼠,第3次免疫后2周用100LD50猪丹毒丝菌C43065株进行腹腔攻毒,采用间接ELISA方法检测免疫组小鼠血清的抗体动态变化。【结果】SDS-PAGE结果显示,采用GST Bind Resin纯化试剂盒和电洗脱法纯化得到了66kDa的rSpaA-N和64kDa的天然SpaA,蛋白含量分别为1.34mg/mL和1.26mg/mL,而Western印迹结果表明rSpaA-N和纯化前后的SpaA具有良好的免疫反应性。保护试验结果表明,不同免疫剂量的rSpaA-N组、天然SpaA组和NaOH提取抗原组均能完全保护小鼠受强毒株C43065的致死性攻击,而GST组和生理盐水组小鼠攻毒后全部死亡。ELISA检测结果表明,在不同免疫剂量的rSpaA-N组、天然SpaA组和NaOH提取抗原组小鼠血清中的抗体效价之间无显著差异(P0.05)。【结论】本研究结果表明rSpaA-N具有良好的免疫保护作用,可以作为猪丹毒亚单位疫苗。     

Polyvalent DNA vaccines expressing HA antigens of H5N1 influenza viruses with an optimized leader sequence elicit cross-protective antibody responses

Highly pathogenic avian influenza A (HPAI) H5N1 viruses are circulating among poultry populations in parts of Asia, Africa, and the Middle East, and have caused human infections with a high mortality rate. H5 subtype hemagglutinin (HA) has evolved into phylogenetically distinct clades and subclades based on viruses isolated from various avian species. Since 1997, humans have been infected by HPAI H5N1 viruses from several clades. It is, therefore, important to develop strategies to produce protective antibody responses against H5N1 viruses from multiple clades or antigenic groups. In the current study, we optimized the signal peptide design of DNA vaccines expressing HA antigens from H5N1 viruses. Cross reactivity analysis using sera from immunized rabbits showed that antibody responses elicited by a polyvalent formulation, including HA antigens from different clades, was able to elicit broad protective antibody responses against multiple key representative H5N1 viruses across different clades. Data presented in this report support the development of a polyvalent DNA vaccine strategy against the threat of a potential H5N1 influenza pandemic.     

Archaeosomes as adjuvants for combination vaccines

The present study evaluated the potential of archaesomes, prepared from the total polar lipids extracted from Methanobrevibacter smithii, as adjuvants for combination (multivalent) vaccines. Groups of Balb/c mice were immunized subcutaneously at day 0 and 21 with one of the following vaccines: trivalent vaccine formulated by the simultaneous co-encapsulation of bovine serum albumine (BSA), ovalbumin (OVA) and hen egg lysozyme (HEL) into archaeosomes (CEC vaccine); an univalent archaeosome vaccine (UVE vaccine) containing either BSA, OVA or HEL; or an admixture vaccine (AMC vaccine) consisting of the three UVE vaccines. Serum specific antibody (IgG + M) responses were determined at day 32, 112 and 203, and specific IgG1 and IgG2a responses were determined at day 112. Mice immunized with the CEC of AMC vaccine developed strong and sustained specific antibody responses to all three antigens at a magnitude similar to those seen in control mice immunized with UVE vaccines. Moreover, the serum BSA-, OVA-, and HEL-specific IgG1 and IgG2a levels in the CEC and AMC immunized mice were overall comparable to those of the UVE immunized control mice. Boosting CEC and AMC vaccinated mice with antigens alone at day 203 elicited strong antibody memory responses, comparable to those in the UVE vaccinated groups. These results show that archaeosomes could be used as adjuvants in developing combination vaccines.     

Immune responses to T-dependent and T-independent antigens during visceral leishmaniasis in mice: evidence for altered T-cell regulation of immune responses to non-parasite antigens

Antibody responses to T-dependent and T-"independent" antigens were studied in disease-susceptible (BALB/c and C57BL/10) and disease-resistant (A/J) mice infected with Leishmania donovani chagasi. Disease-susceptible mice but not disease-resistant mice showed a transient decrease in PFC responses to TNP on a T-dependent carrier (BGG) during the period of 4-8 weeks after infection. Infected disease-susceptible animals also showed increased responses to TNP on a type II T-independent carrier (Ficoll), which persisted until at least 14 weeks after infection. The increased responses were associated with a significant increase in anti-TNP antibody of the IgG2b subclass. When T-enriched spleen cells from infected mice and B-enriched spleen cells from uninfected mice were transferred to irradiated recipients immunized with TNP-Ficoll, increased anti-TNP PFC were observed over numbers seen in irradiated recipients which received both B and T cells from uninfected mice. Increased responses to TNP-Ficoll were also induced by prior administration of soluble leishmania extract in CFA. Infected mice immunized with TNP-LPS, a T-independent type I antigen, also had increased anti-TNP antibody responses, but had normal anti-LPS antibody responses. The elevated antibody production which occurred in response to the T-"independent" antigens could not be attributed to the relatively low polyclonal response which occurred in both disease-resistant and disease-susceptible mice infected with L. donovani chagasi. The observations are consistent with leishmania induced, transient alterations in some T-cell functions including response to haptens on T-dependent carriers, and a lack of down regulation of T-"independent" responses. Subtle lesions in immunoregulation may be important correlates of successful protozoal infection and may be responsible for some of the immunologic manifestations of the disease.     

Toxoplasma gondii: cold stress-induced modulation of antibody responses.

Physical or psychological stressors have been shown to have significant consequences in the immune function and the outcome of disease in human and animal models. Recent work has demonstrated that products released during stress, such as glucocorticoids and catecholamines, can profoundly influence the in vitro growth of pathogens by modulating immune responses. The present study examined the effects of a physical stressor (cold stress) on antigens of Toxoplasma gondii that elicits an antibody-mediated immune response during the acute and chronic phases of infection. Sera obtained from different groups of mice subjected to cold stress during the acute and chronic phases of T. gondii infection were used to measure the levels of antibodies and to localize by Western blot the dominant antigens eliciting IgG and IgM antibody responses. Serum antibodies collected from stressed and infected mice recognized antigens different from those recognized by infected mice without stress. During the acute phase, a stronger IgM antibody response against antigens of 30, 42, 54, and 60 kDa was detected in stressed animals at 3 weeks postinfection. In addition, a 5-kDa antigen was specifically detected in mice subjected to stress during the acute and chronic phases of infection. Levels of specific IgG were increased in infected and in infected and stressed animals that underwent stress in the chronic phase. IgM production did not increase following cold stress in the chronic phase. These results suggest that the strong antibody response in stressed animals is associated with longer parasite persistence in circulation. Stress modulated not only the host immune response but also the ability of parasite antigens to elicit specific antibody responses by the host.     

Effective immunotherapy of cancer by DNA vaccination.

Direct injection of naked plasmid DNA either intramuscularly or intradermally induces strong, long-lived cell-mediated and humoral immune responses to the antigen encoded by the gene vaccine. In the present study, we used gene vaccination with naked plasmid DNA to induce prophylactic immune responses to tumor associated antigens. MAGE-1 (melanoma antigen 1) is an ideal candidate for cancer vaccines because it belongs to a family of genes that are expressed in a number of human tumors of various histological types but not in normal adult tissues except for the testis, and because both humoral and cell-mediated immune responses against MAGE-1 antigen were detected in tumor patients. Intradermal administration of plasmid DNA encoding MAGE-1 (pcMAGE1) induced anti-MAGE-1-specific antibody in BALB/c mice. In contrast, no detectable level of anti-MAGE-1 antibody was induced by intramuscular injection of pcMAGE1. Also, intradermal injection of pcMAGE1 was capable of generating CTLs reactive with MAGE-1-transfected murine tumor cells, M-MSV-MAGE1. Most of the mice (8 out of 10) immunized with pcMAGE1 rejected the challenge of M-MSV-MAGE1 tumor cells, compared with control animals most of which developed tumors. This suggests that intradermal DNA vaccination could provide a novel immunotherapy of cancer.     

Antibody responses elicited by a polyvalent vaccine containing synthetic diphtheric, streptococcal and hepatitis peptides coupled to the same carrier

Three synthetic peptides copying fragments of the diphtheria toxin, the M protein of the streptococcus type 24 and the hepatitis B virus surface antigen (HBs) have been conjugated together to the tetanus toxoid. This polyvalent vaccine has been administered to mice. High antibody titers were obtained against the three antigens. No cross-reactivity could be observed between them as demonstrated by the ability of each peptide to inhibit only the antibodies against the natural M protein and the synthetic M protein peptide indicated that the avidity of the antibodies raised against a monovalent streptococcal vaccine were identical to those raised following injection of the polyvalent vaccine. Antibodies raised against the polyvalent streptococcal vaccine were also protective as shown by opsonophagocytic assays.     

超抗原SEA增强小鼠对HBV DNA 疫苗的免疫反应

观察超抗原SEA(D227A)的真核表达载体(pmSEA),对HBVDNA疫苗诱导Balbc小鼠(H2d)免疫应答的调节作用。肌内注射空载体pcDNA3、HBVDNA疫苗加pmSEA佐剂(pHBVS2S+pmSEA)或不加佐剂(pHBVS2S);ELISA法测定血清抗HBs;ELISPOT检测分泌IFNγ的脾淋巴细胞;4h51Cr释放法检测小鼠脾细胞CTL活性。HBVDNA佐剂组免疫小鼠抗HBsAg抗体滴度明显高于不加佐剂组,其IgG1IgG2a的比例不同于多肽免疫组,二者分别为0.282与10。HBVDNA佐剂组均能增强IgG1和IgG2a的产生,是不加佐剂组的1.36、1.73倍。佐剂组小鼠脾淋巴细胞IFNγ的分泌量是不加佐剂组2～3倍。CTL细胞杀伤活性(E:T=100)佐剂组与不加佐剂组分别为:69.77%±7.5%、42.81%±7.7%,差异显著(P<0.05)。HBVDNA疫苗具有较强的免疫原性,能够诱导机体产生特异性的抗体及CTL反应;pmSEA佐剂能够提高小鼠对DNA疫苗的免疫应答,有望成为DNA疫苗的免疫佐剂。     

Antibodies in the serum of golden hamsters experimentally infected with the intestinal trematode Echinostoma caproni.

The serum antibody response in golden hamsters (Mesocricetus auratus) infected with the intestinal trematode Echinostoma caproni was examined with ELISA, SDS-PAGE and Western blot, and IFAT techniques. All methods showed that the hamsters responded slowly but developed a clear positive humoral response to the infection. In most hamsters, an antibody response to infection could not be detected earlier than 11-13 weeks after infection with 6 or 25 metacercariae, and responses were weak when compared to previous results from mice infected with the same parasite. IFAT with positive hamster sera on live juvenile E. caproni showed only fluorescence at the posterior tip, which is a different pattern from that seen using from infected mice, indicating a different response to antigens on the juvenile parasites by these two hosts. The results are discussed in relation to the limited selfcure and development of resistance which is observed in golden hamsters infected with E. caproni.     

Schistosoma mansoni: immediate hypersensitivity to adult antigens in the rat

Antigen fractions from adult S. mansoni, obtained from infected mice, were isolated by a variety of methods. A readily soluble fraction was obtained in good yield by freezing and thawing the schistosomes, while the less soluble residue was fractionated by the use of a number of the methods currently used for the extraction of tissue and cell surface antigens. The dialyzed, centrifuged products were characterized by acrylamide gel disc electrophoresis methods, agar gel precipitin reactions with antisera from rabbits immunized with whole schistosome homogenate, and by Prausnitz-Kustner (P-K) assay with sera from schistosome infected rats. The pattern of P-K reactivity suggested that there were a number of different antigen specificities involved in the reaginic antibody response to schistosome infection in rats. With repeated infection and increased duration of infection, more different antigens seemed to be involved in the reagin response. The schistosome antigen fraction obtained by freezing and thawing was especially reactive with both early infection rat sera and sera from multiply infected rats. Both the soluble fraction isolated by freezing and thawing and residue solubilized materials were found to be able to induce the formation of reagin antibodies on immunization with alum and B. pertussis vaccine.     

Expression and Immunogenicity of Enterotoxigenic <Emphasis Type="Italic">Escherichia</Emphasis> <Emphasis Type="Italic">coli</Emphasis> Heat-Labile Toxin B Subunit in Transgenic Rice Callus

Enterotoxigenic Escherichia coli is one of the leading causes of diarrhea in developing countries, and the disease may be fatal in the absence of treatment. Enterotoxigenic E. coli heat-labile toxin B subunit (LTB) can be used as an adjuvant, as a carrier of fused antigens, or as an antigen itself. The synthetic LTB (sLTB) gene, optimized for plant codon usage, has been introduced into rice cells by particle bombardment-mediated transformation. The integration and expression of the sLTB gene were observed via genomic DNA PCR and western blot analysis, respectively. The binding activity of LTB protein expressed in transgenic rice callus to G_M1-ganglioside, a receptor for biologically active LTB, was confirmed by G_M1-ELISA. Oral inoculation of mice with lyophilized transgenic rice calli containing LTB generated significant IgG antibody titers against bacterial LTB, and the sera of immunized mice inhibited the binding of bacterial LTB to G_M1-ganglioside. Mice orally immunized with non-transgenic rice calli failed to generate detectable anti-LTB IgG antibody titers. Mice immunized with plant-produced LTB generated higher IgG1 antibody titers than IgG2a, indicating a Th2-type immune response. Mice orally immunized with lyophilized transgenic rice calli containing LTB elicited higher fecal IgA antibody titers than mice immunized with non-transgenic rice calli. These experimental results demonstrate that LTB proteins produced in transgenic rice callus and given to mice by oral administration induce humoral and secreted antibody immune responses. We suggest that transgenic rice callus may be suitable as a plant-based edible vaccine to provide effective protection against enterotoxigenic E. coli heat-labile toxin.     

Recombinant Pvs48/45 Antigen Expressed in E. coli Generates Antibodies that Block Malaria Transmission in Anopheles albimanus Mosquitoes

Transmission of malaria parasites from humans to Anopheles mosquitoes can be inhibited by specific antibodies elicited during malaria infection, which target surface Plasmodium gametocyte/gamete proteins. Some of these proteins may have potential for vaccine development. Pvs48/45 is a P. vivax gametocyte surface antigen orthologous to Pfs48/45, which may play a role during parasite fertilization and thus has potential for transmission blocking (TB) activity. Here we describe the expression of a recombinant Pvs48/45 protein expressed in Escherichia coli as a ∼60kDa construct which we tested for antigenicity using human sera and for its immunogenicity and transmission blocking activity of specific anti-mouse and anti-monkey Pvs48/45 antibodies. The protein reacted with sera of individuals from malaria-endemic areas and in addition induced specific IgG antibody responses in BALB/c mice and Aotus l. griseimembra monkeys. Sera from both immunized animal species recognized native P. vivax protein in Western blot (WB) and immunofluorescence assays. Moreover, sera from immunized mice and monkeys produced significant inhibition of parasite transmission to An. Albimanus mosquitoes as shown by membrane feeding assays. Results indicate the presence of reactive epitopes in the Pvs48/45 recombinant product that induce antibodies with TB activity. Further testing of this protein is ongoing to determine its vaccine potential.     

Protective effect of antiganglioside antibodies against experimental Trypanosoma brucei infection in mice

Liposome-associated ganglioside antigens (ganglioside GM1 or bovine brain gangliosides) were prepared to facilitate the potential protective efficacy for Trypanosoma brucei. Mice were immunized with liposome-associated ganglioside GM1 or bovine brain gangliosides intraperitoneally (i.p.). After immunization, significantly higher antigen-specific IgG and IgM antibodies were detected in sera than in the nonimmunized control group. When sera from immunized mice were analyzed for isotype distribution, antigen-specific IgG1, IgG2a, and IgG3 antibody responses were also noted. After immunization, mice were challenged i.p. with 1 x 10(2) cells of T. brucei. Sixty percentage of liposome-associated ganglioside GM1-immunized mice survived the infection, and all the mice immunized with bovine brain gangliosides-containing liposomes survived. However, all control mice died within 7 days after infection. These data demonstrate that liposomes containing ganglioside antigens have the potential usefulness for the induction of a protective immune response against T. brucei infection and suggest the possibility of developing vaccines that may ultimately be used for the prevention of trypanosomiasis.     

Expression and delivery of tetanus toxin fragment C fused to the N-terminal domain of SipB enhances specific immune responses in mice

Live attenuated bacteria can be used as a carrier for the delivery of foreign antigens to a host's immune system. The N-terminal domain of SipB, a translocon protein of the type III secretion system of Salmonella enterica serovar Typhimurium, is required for secretion and outer membrane localization. In the present study, vaccine plasmids for antigen delivery in which the non-toxic tetanus toxin fragment C (TTFC), which contains a T cell epitope, is fused to the N-terminal 160 amino acids of SipB were developed. It was found that the recombinant proteins are secreted into the culture media and localized to the bacterial surface. TTFC-specific antibody responses are significantly increased in mice orally immunized with attenuated S. Typhimurium BRD509 strains carrying TTFC delivery plasmids. When the TTFC delivery cassettes were introduced into a low copy vector, the plasmid was stably maintained in the BRD509 strain and induced an immune response to the TTFC antigen in mice. These results suggest that expression and delivery of heterologous antigens fused to the N-terminus of SipB enhance the induction of antigen-specific immune responses, and that the N-terminal domain of SipB can be used as a versatile delivery system for foreign antigens.