A plasmid immunization construct encoding urease B of Helicobacter pylori induces an antigen-specific antibody response and upregulates the expression of beta-defensins and IL-10 in the stomachs of immunized mice

The objectives of this study were to investigate the efficacy of a prototype DNA immunization construct encoding the urease B subunit enzyme of Helicobacter pylori (H. pylori) for inducing adaptive and innate immune responses in mice immunized via intramuscular or subcutaneous routes and to further explore the adjuvant effects of the CpG motifs in the vector. Antibody, cytokine, and beta-defensin profiles were assessed in the stomachs of immunized animals: experiments were terminated 3 months after immunization because there was a significant increase in the anti-H. pylori urease B antibody response at Week 6 in mice immunized with the urease B construct. A long lasting expression of IL-10 mRNA was noted. Furthermore, a marked and sustained increase in the mRNA expression of beta-defensins was also observed, particularly beta1. This study demonstrates that an H. pylori urease B DNA construct can induce innate as well as adaptive immune responses in the stomachs of immunized mice. Upregulation of beta-defensin gene expression followed immunization and we believe that this is the first report of a DNA vaccine inducing innate anti-microbial responses. Such complex molecular interactions that modulate both innate and adaptive immune responses may be of critical importance in the control of mucosal pathogens, such as H. pylori.     

Intranasal delivery of chitosan-DNA vaccine generates mucosal SIgA and anti-CVB3 protection

Coxsackievirus B3 infections are common causes of acute and chronic myocarditis with no effective prophylactic treatment available. We describe here a prophylactic strategy using chitosan-DNA intranasal immunization to induce CVB3 specific immune responses. Intranasal administration with chitosan-DNA complex prepared by votexing DNA with chitosan, a natural mucus absorption enhancer, resulted in transgenic DNA expression in mouse nasopharynx. Mice immunized with chitosan-DNA (pcDNA3-VP1) encoding VP1, major structural protein of CVB3, produced much higher levels of serum IgG and mucosal secretory IgA compared to mice treated with pcDNA3-VP1 or pcDNA3. Increased virus-specific cytotoxic activity of spleen cells derived from chitosan-DNA vaccinated mice was also determined. Chitosan-pcDNA3-VP1 intranasal immunization resulted in 42.9% protection of mice against lethal CVB3 challenge and a significant reduction of viral load after acute CVB3 infection. Meanwhile no myonecrosis or infiltrating immune cells indicating ongoing myocarditis was detected in hearts of surviving mice treated with chitosan-DNA. Together, Our data show that intranasal delivery of chitosan-DNA vaccine successfully induced mucosal SIgA secretion and might be a promising vaccine candidate to protect against CVB3 infection.     

人巨细胞病毒IE1核酸疫苗的免疫效果研究

[目的]用人巨细胞病毒(HCMV)IE1核酸疫苗pcDNA3.1(-)-IE1免疫BALB/c小鼠,初步研究其产生的体液免疫和细胞免疫应答水平。[方法]将pcDNA3.1(-)-IE1通过肌肉注射免疫BALB/c小鼠,通过PCR测定和免疫组化检测其在肌细胞中的表达,细胞因子测定、淋巴细胞转化实验检测免疫效果。[结果]PCR检测到与IE1大小一致的片段,免疫组化结果显示IE1基因在小鼠肌细胞中表达IE1目的蛋白。小鼠脾淋巴细胞经PHA刺激后,实验组IL-4、IL-2、IFN-γ含量以及淋巴细胞转化率显著增高,与对照组比较差异有统计学意义(P﹤0.05)。[结论]pcDNA3.1(-)-IE1核酸疫苗能在BALB/c小鼠肌细胞中稳定存在并能表达HCMV IE1蛋白,pcDNA3.1(-)-IE1核酸疫苗可诱导BALB/c小鼠脾细胞分泌IL-4、IL-2、IFN-r并刺激BALB/c小鼠脾细胞增殖。     

Enhanced immune responses to E2 protein and DNA formulated with ISA 61 VG administered as a DNA prime–protein boost regimen against bovine viral diarrhea virus

The aim of this study was to develop and test an optimal vaccination strategy against bovine viral diarrhea virus (BVDV) based on the E2 glycoprotein of the BJ1305 strain. To achieve higher E2-specific antibody titers and to broaden the cellular immune response, a plasmid encoding the E2 protein (pcDNA3.1-E2) was constructed and a purified recombinant E2 protein was generated. The E2 protein was emulsified in the adjuvant ISA 61 VG prior to administration. We immunized mice three times with pcDNA3.1-E2 or the recombinant E2 protein or primed twice with pcDNA3.1-E2 and boosted once with the E2 protein. To evaluate the protection against BVDV conferred by the vaccines, the mice were challenged with BVDV strain Oregon C24V after the third immunization. Although all immunized mice developed humoral and cellular immune responses, the E2-specific antibody titers in the DNA prime–protein boost group were significantly higher than those elicited by either the DNA or the protein vaccine. In addition, vaccination with the E2 DNA vaccine induced higher percentages of CD4⁺IFN-γ⁺ T cells and CD8⁺IFN-γ⁺ T cells among total CD3⁺ T cells than the other regimens. The predominant antibody subclass in the vaccinated mice was IgG1. Serum tumor necrosis factor alpha (TNF-α) levels in the DNA prime–protein boost group were significantly higher after the third immunization than in the other groups. Moreover, the mice treated with the DNA prime–protein boost vaccination regimen acquired protection against BVDV challenge, as shown by a significant reduction of viremia, only minor pathological changes, and a lower viral antigen burden than in the control and solo vaccinated mice. These results demonstrate the potential advantage of a DNA prime–protein boost vaccination approach over a solo vaccination for the prevention of BVDV. The ability of this vaccine strategy to control and eradicate BVD in herds warrants further investigation.     

DNA vaccine encoding Middle East respiratory syndrome coronavirus S1 protein induces protective immune responses in mice

The Middle East respiratory syndrome coronavirus (MERS-CoV), is an emerging pathogen that continues to cause outbreaks in the Arabian peninsula and in travelers from this region, raising the concern that a global pandemic could occur. Here, we show that a DNA vaccine encoding the first 725 amino acids (S1) of MERS-CoV spike (S) protein induces antigen-specific humoral and cellular immune responses in mice. With three immunizations, high titers of neutralizing antibodies (up to 1: 10⁴) were generated without adjuvant. DNA vaccination with the MERS-CoV S1 gene markedly increased the frequencies of antigen-specific CD4⁺ and CD8⁺ T cells secreting IFN-γ and other cytokines. Both pcDNA3.1-S1 DNA vaccine immunization and passive transfer of immune serum from pcDNA3.1-S1 vaccinated mice protected Ad5-hDPP4-transduced mice from MERS-CoV challenge. These results demonstrate that a DNA vaccine encoding MERS-CoV S1 protein induces strong protective immune responses against MERS-CoV infection.     

The protective effect of a Schistosoma japonicum Chinese strain 23 kDa plasmid DNA vaccine in pigs is enhanced with IL-12

The schistosome integral membrane protein Sm/Sj23 was initially shown to induce protection in mice as a synthetic peptide vaccine and further, as a plasmid DNA vaccine to induce protection in mice, sheep and water buffalo. In this study we asked if we could induce protection against challenge infection in pigs against Schistosoma japonicum by vaccinating them with a plasmid DNA vaccine encoding the S. japonicum Chinese strain 23 kDa membrane protein. Further, we asked if we could enhance protective efficacy of this vaccine by the addition of IL-12. We compared vaccination with SjC23 plasmid DNA alone or with IL-12 plasmid DNA in pigs. Pigs were immunized three times at three weekly intervals. Thirty Chinese Songjang native pigs were divided into three groups. In group A, each pig was immunized with 500 microg of SjC23 plasmid DNA by intramuscular (i.m.) injection in both buttocks. In group B each pig was immunized with 500 microg of SjC23 plasmid DNA, and 500 microg of each of pcDNA3.1-p35 and 500 microg of pcDNA3.1-p40 DNA by i.m. injection. In group C each pig was immunized with 500 microg of pcDNA3.1 as the control. Thirty days post-vaccination, pigs were challenged with S. japonicum cercariae and adult and egg burdens and granuloma size determined 45 days post-challenge. The results showed that worm reduction rates in SjC23 group compared with control group were 29.2% and in the SjC23 + IL-12 group reduced 58.6%. Similarly the female worm reduction rates were 50.8 and 58.8%, the hepatic egg reduction rates were 48.2 and 56.4%, and the mean square measure reduction rates of hepatic egg granulomas were 48.6 and 44.4%, the mean diameter reduction rates of granulomas were 27.6 and 22.8% in pigs vaccinated with SjC23 or SjC23 + IL-12 compared to plasmid vaccinated pigs, respectively. Analysis of sera from pigs vaccinated with SjC23 showed that 4 of 10 pigs had anti-Sj23 antibody responses; with 5 of 10 pigs positive for anti-Sj23 in the SjC23+IL-12 group. These results suggest that vaccination with Sj23 DNA vaccine induces not only a significant reduction in worm and egg burdens, but also significantly reduces the size of egg granulomas, thus is also anti-pathology.     

Immune responses and protection in different strains of aged mice immunized intranasally with an adjuvant-combined influenza vaccine.

Immune responses and protection against influenza virus infection were compared between young (2 months) and aged (18 months) BALB/c, C3H and C57BL/6 (B6) mice after intranasal vaccination. The mice were immunized with 2.5 microg protein of A/PR/8/34 (PR8) (H1N1) virus vaccine containing a cholera toxin adjuvant. In both the young and aged BALB/c mice, high levels of PR8-specific antibody-forming cell (AFC) responses were induced in the nasal-associated lymphoid tissue (NALT) 7 days after immunization. Nasal wash IgA and serum IgG antibody (Ab) responses to the PR8 haemagglutinin (HA) 4 weeks after immunization were slightly higher in the young mice than in the aged mice. The young mice showed complete protection against challenge infection, while the aged mice showed only a partial protection. In the C3H mice, NALT-AFC, and IgA and IgG Ab responses were higher in the young mice than those in the aged mice in parallel with the more efficient protection in the young mice than in the aged mice. Both the young and aged B6 mice showed no NALT-AFC responses, scarce IgA and IgG Ab responses and no protection. In the BALB/c mice, IgG1 and IgG2a levels were significantly lower in the aged mice. On the other hand, in the C3H mice, only IgG2a level was significantly lower in the aged mice. Similar results were obtained in terms of immune responses and protection between the young and aged mice of three different strains of mice after intra-nasal immunization with 0.1 microg of PR8 vaccine containing the adjuvant, two-times at 4-week intervals. In the B6 mice, the immune response was improved by immunization with a higher dose of the adjuvant-combined vaccine. These results suggest that local Ab responses, as well as systemic Ab responses, are downregulated in aged mice, although the degree of the downregulation of immune responses differs from strain to strain.     

Construction and immunogenicity of DNA vaccines encoding fusion protein of murine complement C3d-p28 and GP5 gene of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome virus (PRRSV) has recently caused catastrophic losses in swine industry worldwide. The commercial vaccines only provide a limited protection against PRRSV infection. At present, DNA vaccine is the focus on the new vaccines. The gene fragment (p28) coding for the molecular adjuvants complement protein C3d (mC3d) from BALB/c mouse was cloned and expressed as a fusion protein for its application in the vaccine study of mice. Three potential vaccines construct units were engineered to contain two, four and six copies of mC3d-p28 coding gene linked to the GP5 gene of PRRSV and one vaccine expressing GP5 alone (pcDNA3.1-GP5) was constructed. Subsequently, the vaccines’ abilities to elicit the humoral and cellular immune responses were investigated in mice. These results showed that significantly enhanced GP5-specific ELISA antibody, GP5-specific neutralizing antibody, IFN-γ level, and IL-4 level, could be induced in mice immunized with DNA construct units encoding the pcDNA3.1-C3d-p28.n-GP5 than those received DNA vaccine expressing GP5 alone (pcDNA3.1-GP5). Analysis of the immunogenicity of different repeats of mC3d-p28 revealed that mC3d-p28 had an enhancing effect on the immunogenicity of antigens, and that six or more repeats of mC3d-p28 may be necessary for efficient enhancement of antigen specific immune responses. This approach may provide a new strategy for the development of efficient vaccines against the PRRSV for pigs in the future.     

A comparison of immunogenicity and in vivo distribution of Salmonella enterica serovar Typhi and Typhimurium live vector vaccines delivered by mucosal routes in the murine model

We evaluated the immune responses elicited by attenuated Salmonella enterica serovar Typhi vaccine strain CVD 908-htrA and serovar Typhimurium strain SL3261 alone or as live vectors carrying a plasmid encoding fragment C of tetanus toxin (pTETnir15) in mice immunized intranasally and orogastrically, as well as the in vivo distribution of vaccine organisms following immunization. Higher serologic and proliferative responses against both vector and the foreign antigen were elicited when vaccines were delivered by intranasal route. Whereas both Salmonella strains were detected in the nasal tissue, lungs, and Peyer's patches following intranasal and orogastric immunization, larger numbers of vaccine organisms were recovered from these tissues when the vaccines were delivered intranasally.     

A DNA vaccine expressing dengue type 2 virus premembrane and envelope genes induces neutralizing antibody and memory B cells in mice

A dengue DNA vaccine candidate was developed and evaluated for immunogenicity in mice. The vaccine, designated pcD2ME, is a pcDNA3-based plasmid encoding the signal sequence of premembrane (prM), prM and envelope (E) genes of the New Guinea C strain of dengue type 2 virus. CHO-K1 cells transfected with pcD2ME expressed prM and E as determined by immunochemical staining with monoclonal antibodies. BALB/c mice inoculated intramuscularly with 100 microg of pcD2ME two or three times at an interval of 2 weeks developed a low level of neutralizing antibody (1:10 at a 90% plaque reduction). Immunization twice with 10 microg or 1 microg of pcD2ME or three times with 100 microg of pcDNA3 did not induce detectable levels of neutralizing antibody. Mice immunized two or three times with 100 microg of pcD2ME raised neutralizing antibody titers to 1:40 or greater on days 4 and 8 after challenge with 3x10(5) plaque forming units (PFU) of the New Guinea C strain of dengue type 2 virus, showing strong anamnestic responses to the challenge. In contrast, mice immunized two or three times with 100 microg of pcDNA3 developed no detectable neutralizing antibody on days 4 and 8 after challenge. These results indicate that immunization with pcD2ME induces neutralizing antibody and dengue type 2 virus-responsive memory B cells in mice.     

Intranasal immunization with liposome-formulated Yersinia pestis vaccine enhances mucosal immune responses

The induction of mucosal immune responses by a liposome-formulated Y. pestis vaccine (formaldehyde-killed whole cell vaccine; KWC) was evaluated. We demonstrated that intranasal immunization of mice with Y. pestis KWC vaccine, formulated with liposomes, significantly enhanced mucosal immune responses in the lung when compared to the responses induced with KWC vaccine alone. These immune responses were characterized by increased titres of specific IgA and IgG in mucosal secretions (lung and nasal washes), and an increased frequency of specific antibody-secreting cells in the lungs. In addition, antigen-specific proliferative responses and IFN-gamma-secreting cells were also significantly enhanced in the spleens of mice immunized with the KWC vaccine formulated in liposomes. Animals that were immunized intranasally with the KWC vaccine showed significant protection against an intranasal challenge with Y. pestis. These results highlight the importance of mucosal administration of vaccine antigens to stimulate immunity in the respiratory tract and demonstrate that liposome formulations can improve the effectiveness of conventional vaccines.     

DNA vaccines induce partial protection against Leishmania mexicana

As part of an ongoing effort to develop a vaccine against Leishmania mexicana, we tested DNA vaccines encoding L. mexicana GP63, CPb, and LACK, and L. amazonensis GP46, to evaluate this strategy and define the best antigen candidates. Immune responses and vaccine efficacy were evaluated in BALB/c mice immunized with plasmid DNA encoding the different antigens. All four DNA vaccines induced Leishmania-specific humoral and lympho-proliferative immune responses. However, only mice immunized with VR1012-GP46, VR1012-GP63 and VR1012-CPb were partially protected against infection, as evidenced by reduced lesion size and parasite burden. Interestingly, immunization of mice with a mixture of these three plasmids further increased protection. Thus, plasmids encoding CPb, GP63 and GP46 represent good candidates for further development of DNA vaccines against L. mexicana.     

Immunization with plasmid DNA encoding the integral membrane protein, Sm23, elicits a protective immune response against schistosome infection in mice.

Schistosomes are helminth parasites infecting at least 200 million people worldwide. In this study, we evaluated the feasibility of using a nucleic acid vaccine to induce protective immune responses to the Schistosoma mansoni integral membrane protein Sm23. C57BL/6 mice were immunized by intramuscular injection in three separate vaccination trials. ELISA and Western Blot analyses indicated that mice immunized with a DNA plasmid construct encoding Sm23 (Sm23-pcDNA) generated specific IgG for Sm23, while sera from mice immunized with the control pcDNA plasmid did not. The vaccine elicited IgG(2a), and IgG(1) antibody isotypes. We also tested the adjuvant activity of IL-12 and IL-4 on humoral responses to Sm23. Co-immunization with plasmid encoding IL-12 did not affect the level of anti-Sm23 IgG(2a), but did reduce the IgG(1) level. In contrast, co-injection with a plasmid encoding IL-4 significantly reduced the level of anti-Sm23 IgG(2a), while the level of IgG(1) was largely unchanged. Importantly, the Sm23-pcDNA vaccine provided statistically significant levels of protection against challenge infection (21-44%, P<0.001-0.02). Co-administration of plasmids encoding either IL-12 or IL-4 did not significantly enhance this protective effect.     

Intranasal immunization with phosphorylcholine induces antigen specific mucosal and systemic immune responses in mice

Phosphorylcholine (PC) is a structural component of a wide variety of pathogens including Streptococcus pneumoniae and Haemophilus influenzae, and anti-PC immune responses are known to protect mice against invasive bacterial diseases. The present study tested the capability of PC as an intranasal plurispecific vaccine against upper airway infections. BALB/c mice immunized with intranasal PC-keyhole limpet hemocyanin (KLH) plus cholera toxin (CT) as a mucosal adjuvant showed increased PC-specific IgM in serum, IgA in nasal wash and saliva, and numbers of PC-specific nasal and splenic antibody producing cells. Enhanced production of IL-4 and IFN-gamma by CD4+ T cells indicated the participation of Th2- and Th1-type cells. Salivary IgA antibodies produced by intranasal immunization with PC-KLH plus CT reacted to most strains of S. pneumoniae and H. influenzae. Further we demonstrated that the clearance of S. pneumoniae and H. influenzae from the nasal tract was significantly enhanced by nasal immunization with PC-KLH and CT. Thus, intranasal vaccination to induce PC-specific immune responses might help to prevent upper airway infections caused by S. pneumoniae and H. influenzae.     

DNA vaccination based on pyolysin co-immunized with IL-1β enhances host antibacterial immunity against Trueperella pyogenes infection

Trueperella pyogenes is a commensal and opportunistic pathogen normally causes mastitis, liver abscesses and pneumonia of economically important livestock. To date, no specific control measure was reported to prevent T. pyogenes infections. In this study, we first constructed a recombinant plasmid pVAX1-PLO based on the main virulent factor pyolysin gene as DNA vaccine against T. pyogenes infection. Subsequently, transient expression of pVAX1-PLO and pcDNA3.1/V5-fIL-1β were identified in Human embryonic kidney cells (HEK293T) by immunofluorescence assay. Humoral and cellular immune responses were evaluated in mice to compare the immunogenicity between different immunized groups. The results showed that the successful expression of PLO or fIL-1β protein was detected by confocal microscopy for cells transfected with plasmid pVAX1-PLO and/or pcDNA3.1/V5-fIL-1β. The mice immunized with pVAX1-PLO elicited a higher titer of PLO-specific antibody than the control group. The levels of IFN-γ and IL-2 were significantly increased in the pVAX1-PLO immunized mice, while the expression level of IL-4 was slightly increased but not significant. These findings suggested that the DNA vaccine pVAX1-PLO can primarily induce Th1 immune response. The residual Colony-Forming Units (CFUs) from the liver and peritoneal fluid were decreased obviously in the pVAX1-PLO treated mice compared with the control. Importantly, co-immunization with pcDNA3.1/V5-fIL-1β and pVAX1-PLO could enhance host humoral and cellular immune responses and significantly protect mouse from T. pyogenes infection. In conclusion, our study provides a promising strategy against T. pyogenes infections and implies the potential clinical application of combined DNA vaccines in diseases control.     

Poliovirus replicons encoding the B subunit of Helicobacter pylori urease elicit a Th1 associated immune response.

The development of a vaccine for Helicobacter pylori is a key strategy for reducing the worldwide prevalence of H. pylori infection. Although immunization with recombinant B subunit of H. pylori urease (ureB) has yielded promising results, for the most part, these studies relied on the use of strong adjuvant, cholera toxin, precluding the use in humans. Thus, the development of new vaccine strategies for H. pylori is essential. Previous studies from our laboratory have described a vaccine vector based on poliovirus in which foreign genes are substituted for the poliovirus capsid genes. The genomes encoding foreign proteins (replicons) are encapsidated into authentic poliovirions by providing the capsids in trans. To test the utility of replicons as a vaccine vector for H. pylori, a replicon was constructed which encodes ureB. Expression of ureB in cells from the replicon was demonstrated by metabolic labeling followed by immunoprecipitation with anti-urease antibodies. To investigate the immunogenicity of the replicons, mice containing the transgene for the receptor for poliovirus were immunized via the intramuscular route. Mice given three doses of replicons did not develop substantial antibodies to ureB as determined by Western blot analysis using lysates from H. pylori. In contrast, mice given two doses of replicon followed by a single injection of recombinant ureB developed serum antibodies to ureB which were predominately IgG2a. Splenic lymphocytes from mice immunized with replicons alone, or replicons plus recombinant ureB produced abundant interferon-gamma and no detectable interleukin-4 upon stimulation with recombinant ureB. These results establish that poliovirus replicons encoding H. pylori ureB are immunogenic and induce primarily a T helper 1 associated immune response.     

A recombinant P4 protein of Haemophilus influenzae induces specific immune responses biologically active against nasopharyngeal colonization in mice after intranasal immunization

Outer membrane protein P4, together with P6, is highly conserved among all typeable and nontypeable strains of Haemophilus influenzae (H. influenzae). Thus, the protein is an attractive antigen for the inclusion in a vaccine against nontypeable H. influenzae (NTHi). However, the ability of P4 to induce antibodies protective against NTHi infections is still controversial. In this study, we investigated the specific mucosal immune responses against NTHi induced by intranasal immunization with the lipidated form of recombinant P4 protein (rP4) and non-fatty acylated recombinant P6 protein (rP6) with or without cholera toxin (CT) in BALB/c mice model. Intranasal immunization with either rP4+CT, a mixture of rP4 and rP6+CT, or rP4 and rP6 without CT elicited anti-rP4 specific IgG antibody in serum of mice. Intranasal immunization with either rP4+CT or a mixture of rP4, rP6+CT elicited anti-rP4 specific IgA antibody in nasopharyngeal washing (NPW), while intranasal immunization with rP4 and rP6 without CT did not induced anti-rP4 specific IgA antibody responses in NPWs. Sera from mice intranasally immunized with rP4+CT and a mixture of rP4, rP6+CT also showed bactericidal activity. Significant clearance of NTHi in nasopharynx was seen 3 days after the inoculation of live NTHi in mice intranasally immunized with rP4+CT. The current findings suggested that P4 would be a useful antigen as the component of the vaccine to induce protective immune responses against NTHi. The use of an intranasal vaccine composed of the different surface protein antigens is an attractive strategy for the development of a vaccine against NTHi.     

B族链球菌多糖—蛋白质结合物黏膜免疫小鼠血清IgG研究

目的探讨B族链球菌荚膜多糖-破伤风类毒素结合物（GBS-CPS-TT）,经不同免疫途径免疫小鼠的可行性及免疫剂量。方法经滴鼻、灌胃、皮下注射途径免疫小鼠,各组均免疫3次,每次免疫间隔时间2周,免疫后1周时采集血清,采用间接酶联免疫吸附实验（ELISA）检测血清中特异性IgG的抗体滴度。应用统计软件SPSS13.0对数据进行统计学分析,组间均数比较采用方差分析。结果 GBS-CPS-TT经滴鼻免疫、灌胃免疫和皮下注射均可以诱导产生特异性血清IgG抗体。IgG抗体滴度分别为：滴鼻5μg组（2.671±0.207）;滴鼻10μg组（2.911±0.263）;皮下注射5μg组（2.866±0.251）;灌胃10μg组（2.851±0.224）。滴鼻10μg组诱导产生的IgG抗体滴度明显高于滴鼻5μg组（P〈0.01）。结论 GBS-CPS-TT经滴鼻免疫小鼠后可产生系统性免疫应答。     

Toxoplasma gondii immune mapped protein-1 (TgIMP1) is a novel vaccine candidate against toxoplasmosis

Immune mapped protein1 (IMP1) is a new protective protein in apicomplexan parasites, and exists in Toxoplasma gondii. In the present study, a DNA vaccine expressing IMP1 of T. gondii was constructed and the immune response induced in BALB/c mice was evaluated. The coding sequence of IMP1 was inserted into the eukaryotic expression vector pcDNA 3.1(+), resulting a recombinant plasmid pcDNA-IMP1, which was used to immunize BALB/c mice intramuscularly. After immunization, the immune response was evaluated using lymphoproliferative assay, and cytokine and antibody measurements. The mice were challenged with tachyzoites of the virulent T. gondii RH strain 14th day after the last immunization to observe the survival time. The results showed that the group immunized with pcDNA-IMP1 developed a high level of specific antibody responses against Escherichia coli expressed recombinant TgIMP1, with high IgG antibody titers, predominance of IgG2a production, a strong lymphoproliferative response, and significant levels of IFN-γ, IL-2, IL-4 and IL-10 production compared with the control groups. These results demonstrate that pcDNA-IMP1 could elicit strong humoral and Th1 immune responses. Immunized mice showed a significantly (15.8 ± 6 days) prolonged survival time compared with control mice, which died within 7 days of challenge infection. These results suggest that IMP1 is a promising vaccine candidate against toxoplasmosis.     

Intranasal immunization of mice with recombinant lipidated P2086 protein reduces nasal colonization of group B Neisseria meningitidis

Neisseria meningitidis is a major cause of bacterial meningitis in the human population, especially among young children. There is a need to develop a non-capsular vaccine to prevent meningococcal B infections due to the inadequate immune response elicited against the capsular polysaccharide of these strains. Previously, we developed a Swiss Webster adult mouse intranasal challenge model for group B N. meningitidis and evaluated several potential vaccine candidates including a meningococcal outer membrane protein, P2086, through parenteral immunization. Since N. meningitidis is a respiratory pathogen, a mucosal immune response may play an important role in the defense against meningococcal infections. Thus, intranasal immunization may be more effective than traditional parenteral immunization. In this study, mice were immunized intranasally with purified recombinant lipidated P2086 protein (rLP2086) adjuvanted with either CT-E29H, a genetically modified cholera toxin that is significantly reduced in enzymatic activity and toxicity or RC529-AF, a synthetic immunostimulant molecule in aqueous formulation. rLP2086-specific serum and mucosal IgG and IgA antibodies were induced. IgG antibodies reacted with whole cells of multiple strains of group B N.meningitidis. The antibodies have functional activity against N. meningitidis as demonstrated by bactericidal assays. Moreover, immunized mice exhibited reduced nasal colonization of group B meningococcal strains in the intranasal challenge model. These results demonstrate that an intranasal immunization with rLP2086 protein formulated with a detoxified cholera toxin or RC529-AF could prevent the initial colonization of group B meningococcus and become an effective immunization strategy against group B N. meningitidis.