Potential challenges for large-scale uses of RTS, S/AS01 vaccine in malaria-endemic areas / 中国血吸虫病防治杂志

RTS, S/AS01 vaccine has recently been recommended by the WHO for large-scale uses in malaria-endemic areas, which is a milestone in the history of the fight against parasitic infections. Nevertheless, RTS, S/AS01 vaccine is not perfect. Hereby, the shortages of RTS, S/AS01 malaria vaccine were discussed, and the potential challenges during the research and development of next-generation malaria vaccines were analyzed.

Nucleoprotein vaccine induces cross-protective cytotoxic T lymphocytes against both lineages of influenza B virus

PURPOSE: The influenza B virus diverges into two antigenically distinct lineages: B/Yamagata and B/Victoria. Influenza B is the dominant circulating virus during some influenza seasons, and recent data demonstrated that influenza A and B infection similarly cause severe clinical symptoms in hospitalized patients. Nucleoprotein (NP) is a good target for a universal influenza vaccine. This study investigated whether NP epitope variation within two lineages affects the dominant cytotoxic T lymphocyte (CTL) responses induced by vaccination and the resultant protective immunity. MATERIALS AND METHODS: The NP of B/Yamagata/16/1988, the representative strain of the Yamagata lineage, includes a dominant CTL epitope, FSPIRITFL, while B/Shangdong/7/1997 from the Victoria lineage has one amino acid difference in this sequence, FSPIRVTFL. Two recombinant replication-deficient adenovirus (rAd)-vectored vaccines expressing either NP were prepared (rAd/B-NP(I) and rAd/B-NP(V), respectively) and administered to BALB/c mice intranasally. To examine the efficacy of vaccination, antibody responses, CTL responses, and morbidity/mortality after challenge were measured. RESULTS: Both vaccines induce similar antibody and CD8 T-cell responses cross-reacting to both epitopes, and also confer cross-protection against both lineages regardless of amino acid difference. CONCLUSION: The rAd-vectored vaccine expressing the NP could be developed as universal influenza B vaccine which provides broader protection.

Isolation and Characterization of Vaccine Candidate Genes Including CSP and MSP1 in Plasmodium yoelii

Malaria is an infectious disease affecting humans, which is transmitted by the bite of Anopheles mosquitoes harboring sporozoites of parasitic protozoans belonging to the genus Plasmodium. Despite past achievements to control the protozoan disease, malaria still remains a significant health threat up to now. In this study, we cloned and characterized the full-unit Plasmodium yoelii genes encoding merozoite surface protein 1 (MSP1), circumsporozoite protein (CSP), and Duffy-binding protein (DBP), each of which can be applied for investigations to obtain potent protective vaccines in the rodent malaria model, due to their specific expression patterns during the parasite life cycle. Recombinant fragments corresponding to the middle and C-terminal regions of PyMSP1 and PyCSP, respectively, displayed strong reactivity against P. yoelii-infected mice sera. Specific native antigens invoking strong humoral immune response during the primary and secondary infections of P. yoelii were also abundantly detected in experimental ICR mice. The low or negligible parasitemia observed in the secondary infected mice was likely to result from the neutralizing action of the protective antibodies. Identification of these antigenic proteins might provide the necessary information and means to characterize additional vaccine candidate antigens, selected solely on their ability to produce the protective antibodies.

DNA Vaccines Encoding Toxoplasma gondii Cathepsin C 1 Induce Protection against Toxoplasmosis in Mice

Toxoplasma gondii cathepsin C proteases (TgCPC1, 2, and 3) are important for the growth and survival of T. gondii. In the present study, B-cell and T-cell epitopes of TgCPC1 were predicted using DNAstar and the Immune Epitope Database. A TgCPC1 DNA vaccine was constructed, and its ability to induce protective immune responses against toxoplasmosis in BALB/c mice was evaluated in the presence or absence of the adjuvant α-GalCer. As results, TgCPC1 DNA vaccine with or without adjuvant α-GalCer showed higher levels of IgG and IgG2a in the serum, as well as IL-2 and IFN-γ in the spleen compared to controls (PBS, pEGFP-C1, and α-Galcer). Upon challenge infection with tachyzoites of T. gondii (RH), pCPC1/α-Galcer immunized mice showed the longest survival among all the groups. Mice vaccinated with DNA vaccine without adjuvant (pCPC1) showed better protective immunity compared to other controls (PBS, pEGFP-C1, and α-Galcer). These results indicate that a DNA vaccine encoding TgCPC1 is a potential vaccine candidate against toxoplasmosis.

Mucosal Immunization with Recombinant Adenovirus Encoding Soluble Globular Head of Hemagglutinin Protects Mice Against Lethal Influenza Virus Infection

Influenza virus is one of the major sources of respiratory tract infection. Due to antigenic drift in surface glycoproteins the virus causes annual epidemics with severe morbidity and mortality. Although hemagglutinin (HA) is one of the highly variable surface glycoproteins of the influenza virus, it remains the most attractive target for vaccine development against seasonal influenza infection because antibodies generated against HA provide virus neutralization and subsequent protection against the virus infection. Combination of recombinant adenovirus (rAd) vector-based vaccine and mucosal administration is a promising regimen for safe and effective vaccination against influenza. In this study, we constructed rAd encoding the globular head region of HA from A/Puerto Rico/8/34 virus as vaccine candidate. The rAd vaccine was engineered to express high level of the protein in secreted form. Intranasal or sublingual immunization of mice with the rAd-based vaccine candidates induced significant levels of sustained HA-specific mucosal IgA and IgG. When challenged with lethal dose of homologous virus, the vaccinated mice were completely protected from the infection. The results demonstrate that intranasal or sublingual vaccination with HA-encoding rAd elicits protective immunity against infection with homologous influenza virus. This finding underlines the potential of our recombinant adenovirus-based influenza vaccine candidate for both efficacy and rapid production.

Glutamine and Leucine Provide Enhanced Protective Immunity Against Mucosal Infection with Herpes Simplex Virus Type 1

Besides their role as building blocks of protein, there are growing evidences that some amino acids have roles in regulating key metabolic pathways that are necessary for maintenance, growth, reproduction, and immunity. Here, we evaluated the modulatory functions of several amino acids in protective immunity against mucosal infection of herpes simplex virus type 1 (HSV-1). We found that glutamine (Gln) and leucine (Leu) showed enhanced protective immunity to HSV-1 mucosal infection when two administration of Gln and single administration of Leu per day, but not when administered in combinations. Ameliorated clinical signs of HSV-1 challenged mice by the intraperitoneal administration of Gln and Leu were closely associated with viral burden and IFN-gamma production in the vaginal tract at 2 and 4 days post-infection. In addition, the enhanced production of vaginal IFN-gamma appeared to be caused by NK and HSV-1 antigen-specific Th1-type CD4+ T cells recruited into vaginal tract of mice treated with Gln and Leu, which indicates that IFN-gamma, produced by NK and Th1-type CD4+ T cells, may be critical to control the outcome of diseases caused by HSV-1 mucosal infection. Collectively, our results indicate that intraperitoneal administration of Gln and Leu following HSV-1 mucosal infection could provide beneficial effects for the modulation of protective immunity, but dosage and frequency of administration should be carefully considered, because higher frequency and overdose of Gln and Leu, or their combined treatment, showed detrimental effects to protective immunity.

Baculovirus-based Vaccine Displaying Respiratory Syncytial Virus Glycoprotein Induces Protective Immunity against RSV Infection without Vaccine-Enhanced Disease

BACKGROUND: Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract diseases in infancy and early childhood. Despite its importance as a pathogen, there is no licensed vaccine against RSV yet. The attachment glycoprotein (G) of RSV is a potentially important target for protective antiviral immune responses. Recombinant baculovirus has been recently emerged as a new vaccine vector, since it has intrinsic immunostimulatory properties and good bio-safety profile. METHODS: We have constructed a recombinant baculovirus-based RSV vaccine, Bac-RSV/G, displaying G glycoprotein, and evaluated immunogenicity and protective efficacy by intranasal immunization of BALB/c mice with Bac-RSV/G. RESULTS: Bac-RSV/G efficiently provides protective immunity against RSV challenge. Strong serum IgG and mucosal IgA responses were induced by intranasal immunization with Bac-RSV/G. In addition to humoral immunity, G-specific Th17- as well as Th1-type T-cell responses were detected in the lungs of Bac-RSV/G-immune mice upon RSV challenge. Neither lung eosinophilia nor vaccine-induced weight loss was observed upon Bac-RSV/G immunization and subsequent RSV infection. CONCLUSION: Our data demonstrate that intranasal administration of baculovirus-based Bac-RSV/G vaccine is efficient for the induction of protection against RSV and represents a promising prophylactic vaccination regimen.

Immunogenicity and Protective Efficacy of a Dual Subunit Vaccine Against Respiratory Syncytial Virus and Influenza Virus

Respiratory syncytial virus (RSV) and influenza virus are the most significant pathogens causing respiratory tract diseases. Composite vaccines are useful in reducing the number of vaccination and confer protection against multiple infectious agents. In this study, we generated fusion of RSV G protein core fragment (amino acid residues 131 to 230) and influenza HA1 globular head domain (amino acid residues 62 to 284) as a dual vaccine candidate. This fusion protein, Gcf-HA1, was bacterially expressed, purified by metal resin affinity chromatography, and refolded in PBS. BALB/c mice were intranasally immunized with Gcf-HA1 in combination with a mucosal adjuvant, cholera toxin (CT). Both serum IgG and mucosal IgA responses specific to Gcf and HA1 were significantly increased in Gcf-HA1/CT-vaccinated mice. To determine the protective efficacy of Gcf-HA1/CT vaccine, immunized mice were challenged with RSV (A2 strain) or influenza virus (A/PR/8/34). Neither detectable viral replication nor pathology was observed in the lungs of the immune mice. These results demonstrate that immunity induced by intranasal Gcf-HA1/CT immunization confers complete protection against both RSV and homologous influenza virus infection, suggesting our Gcf-HA1 vaccine candidate could be further developed as a dual subunit vaccine against RSV and influenza virus.

Anti-infective immunity of recombinant Bifidobacteria bifidum-Eg95 vaccine of Echinococcus granulosus in mice / 中国地方病学杂志

Objective To investigate the protective immunity in mice immunized with recombinantBifidobacteria bifidum(Bb)-Eg95 vaccine of Echinococcus granulosus (Eg) and challenged with Eg protoscoleces.Methods Fifty-six female BALB/c mice 12-14 weeks old and weighed 20-25 g were vaccinated with the recombinant Bb-Eg95 vaccine subcutaneously,intramuscularly,intranasally and orally,respectively,with blank vector,Bb and medium of solution(MRS) as control,8 mice in each group.Mice were challenged with Eg protoscoleces on week 8 after immunization and killed on week 25 after infection.The weight of hydatid cyst was measured and the decreased larva rate was calculated.Sera were collected to determine the levels of IgE,IgG and its subclasses by enzyme linked immunosorbent assay(ELISA).Splenocytes were collected and cultivated to test the proliferation of splenocytes using methyltetrazolium (MTT) assay under EgAg and concanavalin A (ConA) stimulation.The results were compared with analysis of variance and the comparison between two groups was performed with LSD-t test.Results There was significant difference in the weight of hydatid cyst between groups (F =11.062,P ＜ 0.05).Compared with MRS control group[(0.075 ± 0.019)g],the hydatid cyst weight decreased in subcutaneous group [(0.050 ± 0.013)g],intramuscular group[(0.050 ± 0.019)g],intranasal group[(0.028 ± 0.016)g] and oral group [(0.031 ± 0.018)g,all P ＜ 0.01).Compared with subcutaneous and intramuscular groups,the hydatid cyst weight decreased in intranasal and oral groups(all P ＜ 0.05).The decreased larva rate was inversely proportional to the weight of hydatid cyst.There was significant difference in the levels(obsorbancy,A) of IgG,IgG2a,IgG2b,IgG1,IgG3 and IgE between these groups(F =21.774,36.977,27.071,14.746,10.131,9.444,P ＜ 0.05 or P ＜ 0.01).Compared with MRS control group (0.015 ± 0.002,0.002 ± 0.001,0.003 ± 0.001),the levels of IgG,IgG2a and IgG2b increased in subcutaneous group(0.022 ± 0.004,0.007 ± 0.002,0.008 ± 0.002),intramuscular group (0.023 ± 0.003,0.008 ± 0.002,0.007 ± 0.002),intranasal group(0.032 ± 0.007,0.012 ± 0.002,0.013 ± 0.004)and oral group(0.028 ± 0.006,0.010 ± 0.003,0.010 ± 0.002,P ＜ 0.05 or P ＜ 0.01).Compared with subcutaneous and intramuscular groups,the levels of IgG,IgG2a and IgG2b increased in intranasal and oral groups(P ＜ 0.05 or P ＜ 0.01).Compared with MRS control group(0.009 ± 0.001,0.009 ± 0.002,0.009 ± 0.001),the levels of IgG1,IgG3 and IgE decreased in subcutaneous group(0.022 ± 0.004,0.007 ± 0.002,0.008 0.002),intramuscular group(0.004 ± 0.001,0.004 ± 0.001,0.004 ± 0.002),intranasal group(0.005 ± 0.002,0.005 ± 0.003,0.005 ± 0.002)and oral group(0.005 ± 0.001,0.004 ± 0.002,0.004 ± 0.003,all P ＜ 0.01).There was significant difference in the proliferation of splenocytes in the supernatant of cultured splenocyte,of cultured splenocyte + EgAg and of cultured splenocyte + ConA(F =63.975,359.833,167.399,P ＜ 0.01).There was significant difference in the proliferation of splenocytes inside groups(F =6741.955,4953.667,869.320,201.235,175.413,139.653,169.994,all P ＜0.01).Compared with the cultured splenocyte the proliferation of splenocytes increased in the cultured splenocyte +EgAg and splenocyte + ConA (all P ＜ 0.01).Compared with the cultured splenocyte + EgAg,the proliferation of splenocytes increased in the cultured splenocyte + ConA(P ＜ 0.01).Conclusion An effective and protective immunity is induced by the recombinant Bb-Eg95 vaccine of Eg in mice.

The nfa1 Gene Contributed on the Contact-dependent Pathogenic Mechanisms of Naegleria fowleri / 한양의대학술지

Free-living Naegleria fowleri is a causal agent of primary amoebic meningoencephalitis in mainly children and young adults. An nfa1 gene, encoding 360 bp of nucleotides, was cloned from a N. fowleri cDNA library by SEREX method. By immunohistochemistry and a confocal microscope, Nfa1 protein was found in amoebic pseudopods, especially in food-cups, when amoeba was in contact with target cells. When an anti-Nfa1 antibody was added to the coculture system, the cytotoxicity of N. fowleri trophozoites onto target cells was decreased, and the severe morphological destruction of rat microglial cells cocultured with N. fowleri trophozoites was reduced. In a tansfection system, an expression vector with an nfa1 gene was successful transfected into nonpathogenic N. gruberi, and transgenic N. gruberi showed the increasing in vitro cytotoxicity. The siRNA decreased the expression levels of nfa1 mRNA and Nfa1 protein in transfected N. fowleri trophozoites. On the immunization of mice with the rNfa1 protein, the protective immunity of host was induced. Thus, mice showed the prolonged mean survival times in PAM-developed mice. In final, the nfa1 gene and Nfa1 protein play an important role in the pathogenesis of N. fowleri infection.

Purification of native F1 antigen from Yersinia pestis EV76 anti its efficacy against Yersinia pestis in mice / 中华微生物学和免疫学杂志

Objective To purify native F1 antigen from E pestis EV76 strain and determine its ef-ficacy against Y. pestis. Methods A new purification method was developed by the substitution of physical disruption ( glass beads) for organic solvent ( acetone and toluene) one, followed by a combination of ammo-nium sulfate fractionation and SephacrylS-200HR column filtration chromatography. Groups of mice were im-munized with F1 antigen adsorbed to 25% aluminum hydroxide in PBS by intramuscular route. The immu-nized animals were challenged subeutaneously(s, c. ) with 104 CFU of Y. pestis strain 141 at 18 weeks after the primary immunization. Results There was no IgG titre difference between two groups of mice with one-dose immunization, whereas in the two-dose immunization groups, the group F1-40 μg induced a statistically higher antibody titre than the group F1-20 μg. Complete protection was observed for animals immunized with purified F1 antigen by s.c. route. In contrast, the control mice immunized with aluminum hydroxide suc-cumbed to a same dose of Y. pestis 141 challenge. Conclusion This purification strategy is a simple and ef-fective, and can be operated in a large scale. Native F1 antigen extracted from Y. pestis EV76 is highly im-munagenic, and can be used as a key antigen component to develop sub-unit vaccine of plague.

Lambs Infected with UV-Attenuated Sporocysts of Sarcocystis ovicanis Produced Abnormal Sarcocysts and Induced Protective Immunity against a Challenge Infection

The present study surveyed the prevalence of natural infection of the sheep esphagus muscle with sarcocysts of Sarcocystis ovicanis and examined induction of protective immunity using UV-attenuated sporocysts. The overall prevalence of natural infection of the sheep was 95%. Infectivity of the collected sarcocysts was confirmed by shedding of sporulated oocysts after feeding infected esophageal tissues to dogs. To induce protective immunity, lambs were immunized 3 times (once a week) with 1.5 x 10(4) sporocysts exposed to UV-light for 30 min (UV-30 group) or 60 (UV-60 group) min and then challenged with 1.5 x 10(4) normal sporocysts at the 3rd week post the 1st vaccination. These lambs showed high survival and less clinical signs of sarcocystosis than normal infected lambs. The attenuated sporocysts produced abnormal cysts; small in size and detached from the muscle fiber. These abnormalities were more obvious in UV-60 group than UV-30 group. Also, the IFN-gamma level and lymphocyte percentage were increased while the total leukocyte count was decreased in the UV-60 group compared with other groups. The high level of IFN-gamma may be an evidence for the induction of Th1 responses which may have protective effect against a challenge infection.

Protective Immunity and Antibody Response of Rats Infected with Trichinella spiralis / 中国寄生虫学与寄生虫病杂志

Objective To study the protective immunity and antibody(IgG,IgG1 and IgG2a)response against adult and larva infection of T.spiralis Korean isolate in rats.Methods Fony-six rats were randomly divided into 7 groups.Group A(A1,A2,10 rats)was used for the determination of protective efficacy from adult stage infection,group B (B1,B2,14 rats)was for the protective efficacy from muscle larva stage infection,group C(C1,C2,17 rats)was for challenge control,and group D(5 rats)served as normal control.Rats in groups A,B and C were infected with 1000 T.spiralis muscle larvae,and the infected rats were treated with flubendazole(20 mg/ks,10 d)at day 7(A1,A2) and at day 30(B1,B2).Rats in groups A and B were re-infected with 500 T.spiralis muscle larvae at day 10 after treatment.Rats in groups A1 and B1 were killed at day 7 and day 30 to inspect the reduction of adult worms in the intestines.Rats in groups A2 and B2 were killed at day 30 to detect the reduction of muscle larvae in diaphragms.Rats in groups C and D were killed at the same time,and all rats were bled at the same time.Specific anti-Trichinella IgG,IsG1 and IgG2a were detected by ELISA.Results Adult stage infection induced protective efficacy by 100% against adult stage and by 99.96% against larva stage.Larval stage infection induced protective efficacy by 99.92% against adult stage and 99.89% against muscle larvae.Anti-muscle stage larval ES Ag(IgG 3.0,IgG1 2.2,IgG2a 0.8)and anti-adult crude Ag antibodies(IgG 1.9,IgG1 0.8,IgG2a 0.3) significantly increased in the muscle larval stage infection compared to normal control(IgG 0.5,IgG1 0.1,IgG2a 0.1)and adult stage infection(IgG 0.5,IgG1 0.09,IgG2a 0.09) (P<0.01).Higher specific IgG1 antibody(IgG1 2.2) in larva stage infection was shown than specific IgG2a antibody response(IgG2a 0.8)(P<0.01).Conclusion Protective immunity against both adult and larva worms has been induced from adult and muscle larva stage infections of T.spiralis.

Enhancement of protective immune responses by oral vaccination with Saccharomyces cerevisiae expressing recombinant Actinobacillus pleuropneumoniae ApxIA or ApxIIA in mice

We previously induced protective immune response by oral immunization with yeast expressing the ApxIIA antigen. The ApxI antigen is also an important factor in the protection against Actinobacillus pleuropneumoniae serotype 5 infection; therefore, the protective immunity in mice following oral immunization with Saccharomyces cerevisiae expressing either ApxIA (group C) or ApxIIA (group D) alone or both (group E) was compared with that in two control groups (group A and B). The immunogenicity of the rApxIA antigen derived from the yeast was confirmed by a high survival rate and an ApxIA-specific IgG antibody response (p < 0.01). The highest systemic (IgG) and local (IgA) humoral immune responses to ApxIA and ApxIIA were detected in group E after the third immunization (p < 0.05). The levels of IL-1beta and IL-6 after challenge with an A. pleuropneumoniae field isolate did not change significantly in the vaccinated groups. The level of TNF-alpha increased in a time-dependent manner in group E but was not significantly different after the challenge. After the challenge, the mice in group E had a significantly lower infectious burden and a higher level of protection than the mice in the other groups (p < 0.05). The survival rate in each group was closely correlated to the immune response and histopathological observations in the lung following the challenge. These results suggested that immunity to the ApxIA antigen is required for optimal protection.

HIV Vaccine-Challenges and Opportunities / 中国病毒学·英文版

The need for an efficacious HIV/AIDS vaccine remains the highest priority of the world HIV/AIDS agenda. The generation of an efficacious HIV/AIDS vaccine proves an enormous scientific challenge. This article reviews the neutralizing antibody problem, elusive immune protection, immunogen design, pre-existing anti-vector immunity and design of phase 3 vaccine trials and the challenges and opportunities in development of HIV/AIDS vaccine are discussed.

Comparison of the role of dendritic cells and macrophages in inducing protective immunity against Schistosoma japonicum / 中国寄生虫学与寄生虫病杂志

Objective To compare a potential role of dendritic cells (DCs) and macrophages in inducing protective immunity against infection with Schistosoma japonicum. Methods DCs and macrophages were pulsed in vitro with soluble egg antigen (SEA) of S. japonicum. BALB/c mice were injected three times with DCs or macrophages, either antigen-pulsed or not,and challenged with 40 ± 2 cercariae of S. japonicum per mouse. Worms were collected 42 days later by portal perfusion of the mice and egg number of liver was calculated. To evaluate whether protective immunity had been induced by preparations of DCs or macrophages, the worm burden and fertility ( eggs per female per mouse liver) were compared between the groups of mice. The antibody level against SEA was detected by ELISA. Results With respect to mice injected with untreated cells, numbers of worms and eggs per female worms were significantly reduced in the groups of mice having received pulsed DCs (26. 3% and 37.9%, respectively), or pulsed macrophages (22. 0% and 30.7%). Untreated DCs and macrophages induced no significant effects. The antibody level against SEA rose in sera of all groups of mice up to 42 days after the challenge, but most pronounced in those immunized with pulsed DCs, although this was not significantly different from other groups. Conclusion The results suggest that the protective immunity against S. japonicum might be induced by DCs to a higher extent than by macrophages after in vitro pulsing with egg antigen.

Immunogenicity of baculovirus expressed recombinant proteins of Japanese encephalitis virus in mice

Genes encoding for the premembrane and envelope (prME), envelope (E) and nonstructural protein (NS1) of Japanese encephalitis virus (JEV) were cloned. Each protein was expressed in baculovirus expression system. Of the three proteins expressed in baculovirus system, only prME had hemagglutination activity. The prME (72 and 54 kDa), E (54 kDa) and NS1 (46 kDa) proteins could be detected by Western blotting in the recombinant virus infected cells. Immunogenicity of the recombinant proteins obtained from infected Spodoptera frugiperda (Sf-9) cells was examined in mice. The 3 week-old ICR mice immunized intraperitoneally with three recombinant proteins three times were challenged with a lethal JEV. A survival rate was increased from about 7.7% in unimmunized mice to 92.3% in E + prME and only E groups. The complete protection was shown in prME and live vaccine inoculated groups, respectively. We also measured neutralizing antibody and three immunoglobulin subtypes of IgG1, IgG2a and IgG2b in the sera of mice before and after challenge. Titers of IgG1 antibodies were approximately two to three times higher than that of IgG2b antibodies in all the immunized groups as compared to the control group. However, IgG2a antibody level somewhat increased after challenge, indicating T-helper type 1 (Th1) cell response. The results of this study can provide useful information for developing efficacious subunit vaccine against JEV.

INVESTIGATION ON PROTECTIVE EFFECTS OF DNA VACCINE PCDSJ32 FORSCHISTOSOMA JAPONICA BY DIFFERENT INJECTION TIMES AND CHALLENGE TIME AFTER THE LAST INOCULATION IN MICE / 中国人兽共患病学报

Aim Protective immunity of DNA vaccine pCDSj32 for Schistosoma japonica by different injection times and challenge time after the last inoculation in mice was investigated. Methods 100μg/100μl DNA vaccine pCDSj32 was injected into the quadriceps muscles of the BALB/c mice. The mice were divided into once immunized groups and three times immunized groups. Challenge infection was applied 4wk or 8wk after the last inoculation with 40 cercariae each mouse. The adult reduction rates and the EPG in the livers of mice were detected 6wk after challenge. Results Substantially protective immunity was obtained when compared the immunized groups with the control. The adult reduction rates were 35.61～44.44 ％ ,and the egg reduction rates in the livers were 39. 64～69.06％. Conclusion The protective immunity could be influenced by different times of DNA vaccine inoculation and the challenge time after the last immunization. The best protective results could be obtained with inoculation once combined with the challenge 8wk after the immunization of DNA vaccine.

CHEMOTHERAPEUTIC EFFICACY OF PRAZIQUANTEL IN RATS WITH PROTECTIVE IMMUNITY TO CLONORCHIS SINENSIS INFECTION / 中国寄生虫学与寄生虫病杂志

[Objective] To study the synergic effect of praziquantel (PZQ) and host acquired immunity on Clonorchis sinensis. [Methods] Acquired immunity to C. sinensis was induced by immunization with crude adult worm antigen (AW Ag) and excretory-secretory antigen (ES Ag) or infection with C. sinensis metacercariae. The effect was assessed by the worm reduction rate compared with the control groups after challenge infection with 50 metacercariae and treated orally with a subcurative dose of praziquantel (50 mg/kg). Significant test was performed by analysis of variance (ANOVA) and Nparl way Kruskal-Wallis test. All calculations were performed by PC-SAS system. [Results] 1. PZQ was more effective against C. sinensis larvae than against adult worms in the control (P＜0. 001), ES Ag (P＜0.01) or crude AW Ag immunization group (P＜0. 001). 2. As compared with the control, the worm reduction rate after challenge infection was significantly higher (P＜0. 001) in ES Ag immunized group (35.60%) and metacercaria infection group (97.5 % ) and less in crude AW Ag group (23.4 %). The PZQ efficacy was significantly enhanced in ES Ag immunized group. [Conclusion] The efficacy of PZQ against C. sinensis could be synergically enhanced in rats by inducing host acquired immunity.

Construction of DNA Vaccine pcDNA3.1(+)/Tetraspanin 2-A against Schistosoma japonicum and its Immuno-protective Effect in Mice / 中国寄生虫学与寄生虫病杂志

Tetraspanin 2-A(SjTsp2-A) gene was amplified by PCR.pcDNA3.1(+)/SjTsp2-A recombinant plasmids were constructed and transformed into E.coli DH5?.Twenty four BALB/c mice were randomly divided into pcDNA3.1(+) /SjTsp2-A group(A),pcDNA3.1(+)/SjGST group(B) and pcDNA3.1(+) group(C).Each mouse was injected through musculus quadriceps femoris by three times(two weeks interval) respectively with 100 ?g pcDNA3.1(+)/SjTsp2-A,pcDNA3.1(+)/SjGST,or pcDNA3.1(+).At two weeks after the final inoculation,mice were each challenged by 40?2 cercariae of S.japonicum.Forty-five days after infection,all mice were sacrificed,the number of worms collected and eggs in liver tisssue was counted.Anti-pcDNA3.1(+)/SjTsp2-A antibody was detected by ELISA and protein expression in quadriceps muscle by immunohistochemical staining.The worm reduction rate(44.4%) and egg reduction rate(28.4%) of group A was higher than those of group B and C(P