大鼠CD36基因真核表达载体的构建及表达

目的:构建大鼠CD36真核表达载体,并在293T细胞中表达.方法:应用RT-PCR技术,从大鼠肺泡巨噬细胞NR8383细胞提取的总RNA中,获得CD36基因编码序列片段,克隆至真核表达载体pEGFP-N1中,对重组质粒进行酶切和测序鉴定后,以脂质体介导法转染至293T细胞,通过荧光显微镜和Western blot检测其在293T细胞中的表达.结果:酶切和测序证明重组真核表达载体pEGFP-N1-CD36构建成功,荧光显微镜及Western blot确认目的基因序列在293T细胞中过表达.结论:成功构建大鼠CD36基因的重组真核表达载体pEGFP-N1-CD36,并在293T细胞中过表达.     

人RUVBL2真核表达载体的构建及其在HeLa细胞中的表达

目的:构建带有绿色荧光蛋白的RUVBL2真核表达载体pEGFP-N1-RUVBL2,并鉴定其在HeLa细胞中的表达。方法:以pGADT7-RUVBL2质粒为模板,PCR扩增RUVBL2基因,首先克隆至T载体中,进一步亚克隆至p-EGFP-N1,并对重组表达载体进行酶切及测序鉴定。采用脂质体转染法将重组质粒瞬时转染HeLa细胞系,应用荧光显微镜观察绿色荧光融合蛋白的表达,并用Western blot法检测RUVBL2-GFP融合蛋白的表达。结果:经限制性酶切鉴定及测序分析证实pEGFP-N1-RUVBL2载体序列正确;荧光显微镜下可见转染的HeLa细胞中有绿色荧光蛋白的表达,Western blot法证实转染细胞中能表达RUVBL2-GFP融合蛋白。结论:pEGFP-N1-RU-VBL2表达载体构建成功,并在HeLa细胞内成功表达。     

活化的蛋白激酶C受体1真核表达载体的构建与鉴定

目的:构建活化的激酶C受体1(RACK1)WD1-4真核表达载体,通过细胞转染和Western blot鉴定其是否在细胞中表达。方法:应用PCR法扩增RACK1蛋白中第1～4个WD40区域的片段,将其与PGEM-T载体连接,测序后再将其克隆至pEGFP-N1中。采用脂质体法将重组质粒转染至293T细胞中,观察其在真核细胞中的表达,并用Western blot法进行鉴定。结果:pEGFP-N1-RACK1(WD1-4)重组质粒经酶切鉴定及测序证实,目的基因的序列完全正确。荧光显微镜观察发现,转染了重组质粒的细胞株可见绿色荧光融合蛋白的表达,Western blot结果进一步证实了上述结果。结论:成功构建pEGFP-N1-RACK1(WD1-4)重组质粒且进行了真核表达,为下一步研究RACK1蛋白的功能奠定了基础。     

小鼠BTLA慢病毒表达载体的构建及鉴定

目的 构建小鼠BTLA慢病毒表达载体,并对表达产物进行鉴定.方法 以pET-28a-mBTLA质粒为模板,通过PCR技术构建pMD18-T-mBTLA质粒,将小鼠BTLA基因全长编码序列克隆到慢病毒转移载体,通过脂质体转染293T细胞包装成小鼠BTLA慢病毒颗粒.PCR技术和基因测序对重组质粒进行鉴定.荧光显微镜观察重组慢病毒感染293T细胞形态学变化.RT-PCR和Western blot法鉴定BTLA在重组慢病毒感染293T细胞中的表达.50％组织培养感染剂量法(TCID5o法)检测重组慢病毒滴度.结果 成功构建的pMD18-T-mBTLA质粒和pSL6-mBTLA质粒,经双酶切电泳后均出现大小约为1 kb的条带与mBTLA编码序列的大小相符.基因测序并比对分析进一步证实mBTLA编码序列成功整合到质粒载体.病毒上清PCR扩增和293T细胞形态学观察证实Lenti-mBTLA慢病毒包装成功.TCID50法测定Lenti-mBTLA慢病毒滴度为1.3×108 pfu/mL.RT-PCR和Western blot法证实Lenti-mBTLA慢病毒能有效表达mBTLA mRNA和蛋白质.结论 成功构建了表达小鼠BTLA的慢病毒.     

USP22基因克隆及其融合蛋白真核表达载体的构建

目的 克隆人类泛素水解酶22(ubiquitin-specific processing enzyme 22,USP22)基因,构建与绿色荧光蛋白融合表达的真核载体.方法 利用RT-PCR技术以HeLa细胞总RNA为模板分别扩增USP22基因cDNA序列两片段,依次插入真核表达载体pEGFP-N1;重组质粒转染HEK293T细胞,观察融合蛋白表达及绿色荧光的分布.结果 测序结果显示USP22序列与GenBank收录数据一致,酶切显示重组质粒pEGFP-USP22构建无误,质粒转染后有80 %左右HEK293T细胞表达绿色荧光,且在胞质与胞核中广泛分布.结论 成功克隆USP22基因并构建与GFP融合表达的真核载体,为进一步深入研究USP22基因的生物学功能奠定了基础.     

狂犬病病毒糖蛋白真核表达质粒的构建及免疫原性的初步研究

目的 构建狂犬病病毒糖蛋白基因DNA真核表达质粒,并检测其免疫原性.方法 用RT-PCR法扩增和分离CTN株狂犬病病毒糖蛋白基因,测序后克隆至pcDNA5.0载体,构建重组质粒pcDNA5.0-G,提取质粒,转化293T细胞,检测糖蛋白瞬时表达,并以该重组质粒肌肉注射免疫BALB/c小鼠,狂犬病病毒CVS株攻击,观察小鼠存活情况.结果 酶切、测序结果显示重组质粒pcDNA5.0-G构建成功,瞬时表达结果显示糖蛋白获得大量表达.经肌肉注射质粒常规免疫小鼠,病毒攻击后小鼠保护率为73.3％,对照组为6.7％.结论 所构建狂犬病病毒糖蛋白真核表达质粒pcDNA5.0-G经肌肉注射免疫后可有效保护小鼠免受狂犬病病毒攻击,具有良好的免疫原性,这为后期核酸疫苗的研发奠定基础.     

脂质体介导弓形虫SAG1与SAG3复合基因诱导小鼠免疫应答研究

目的评价弓形虫SAG1与SAG3基因真核表达质粒DNA免疫小鼠的免疫应答效果。方法以PCR方法扩增出SAG1与SAG3目的基因片段,并插入载体pEGFP-N3以构建重组质粒pE- SAG1／SAG3,瞬时转染细胞Cos-7。质粒pESAG1／SAG3以10μg剂量,脂质体介导肌肉注射BALB／c小鼠,免疫3次,最后一次免疫后4周,观察体液和细胞免疫。RT-PCR方法检测注射部位目的基因的转录;斑点杂交方法检测目的基因是否与小鼠染色体基因组整合。结果质粒pESAG1／SAG3转染细胞后观察到绿色荧光;Western blot显示pESAG1/SAG3表达识别条带在相对分子质量(Mr)66．2×103附近。小鼠免疫后,血清产生抗弓形虫速殖子抗体,诱导IFN-γ及IL-2水平高于对照组。RT-PCR显示首次免疫15 d后,目的基因在肌肉组织中仍有转录,斑点杂交显示目的基因未与小鼠的基因组发生整合,混合质粒注射的小鼠抗弓形虫感染的存活时间延长。结论脂质体介导弓形虫SAG1与SAG3复合编码基因质粒接种小鼠能明显诱导体液和细胞免疫应答。     

小鼠pdx-1基因真核表达载体的构建及其在胚胎干细胞中的表达

目的： 克隆小鼠pdx-1基因，构建其真核表达载体，并在小鼠胚胎干细胞中表达，为糖尿病的细胞移植治疗奠定基础。方法： PCR扩增小鼠胰腺pdx-1基因 cDNA，酶切后和携带绿色荧光蛋白报告基因的真核表达载体pEGFP-N1重组，将pdx-1基因 cDNA片段连接到pEGFP-N1载体的多克隆位点，形成重组载体pEGFP/pdx-1，转化大肠杆菌DH5α菌株，构建成pdx-1基因真核表达载体质粒。扩增DH5α后抽提质粒DNA，Hind Ⅲ 和BamHⅠ酶切，电泳，DNA测序鉴定。鉴定正确的质粒DNA用脂质体包裹后转染小鼠胚胎干细胞MESPU13。结果： 从小鼠胰腺cDNA扩增出876 bp的DNA片段并成功重组到pEGFP-N1载体中。经酶切和DNA测序验证，插入载体的DNA片段为pdx-1基因，插入方向正确。重组质粒经脂质体转染胚胎干细胞MESPU13，24 h 后观察到绿色荧光蛋白报告基因和目的基因的pdx-1表达。结论： 小鼠pdx-1基因的克隆和真核表达载体构建获得成功，为进一步研究其功能奠定了基础。     

人Gax基因真核表达载体的构建及在血管平滑肌细胞中的表达

目的:构建人Gax基因真核表达载体,并观察在兔血管平滑肌细胞中的表达。方法:通过PCR从pCMV-SPORT6-Gax质粒中扩增出人Gax cDNA片段,经双酶切后装入到有绿色荧光蛋白报告基因的真核表达载体pEGFP-N1中,经限制性内切酶酶切分析和DNA测序鉴定后通过梭华-Sofast转染试剂介导重组质粒转染至兔血管平滑肌细胞中进行表达,通过荧光显微镜观察转染细胞的绿色荧光蛋白表达和RT-PCR扩增转染细胞的cDNA来鉴定Gax在兔血管平滑肌细胞中的表达。结果:琼脂糖凝胶电泳检测PCR扩增产物人Gax基因片段约915bp,与预期分子量相符;酶切分析和测序鉴定证明人Gax真核表达载体pEGFP-N1-Gax连接正确;荧光显微镜观察到重组质粒转染细胞中有绿色荧光蛋白表达,及RT-PCR证明转染细胞有人GaxmRNA表达。结论:成功构建人Gax基因的重组真核表达载体pEGFP-N1-Gax,并证实在兔血管平滑肌细胞中表达,为进一步研究Gax基因在心血管病中的作用提供了实验基础。     

人NOD2基因启动子的绿色荧光蛋白表达载体的构建

人NOD2基因启动子的绿色荧光蛋白表达载体的构建。以人基因组DNA为模板,PCR扩增含有人NOD2基因启动子不同长度的4段序列,利用特定的限制性内切酶位点,以切除启动子的pEGFP-N3作为框架结构,将这4个序列片段进行酶切并插入表达载体pEGFP-N3中,用Vsp I和Pst I双酶切和PCR鉴定重组质粒,再将重组质粒进行DNA序列分析。构建的重组质粒经脂质体LipofectamineTM2000介导转染HTK293T细胞,转染24 h后加入TNF-α持续刺激细胞24 h或不加TNF-α刺激,在倒置荧光显微镜下观察其能否在NOD2基因启动子的调控下表达报告基因绿色荧光蛋白(green fluores-cent proteins,GFP)。结果:pEGFP-N3-NOD2(617 bp)、pEGFP-N3-NOD2(747 bp)、pEGFP-N3-NOD2(1 136 bp)、pEG-FP-N3-NOD2(1 387 bp)分别经酶切鉴定和序列测定证实目的基因已插入重组质粒;细胞转染结果表明,构建的4段重组质粒pEGFP-N3-NOD2(617 bp)、pEGFP-N3-NOD2(747 bp)、pEGFP-N3-NOD2(1 136 bp)、pEGFP-N3-NOD2(1 387 bp)转染的HTK293T均能表达绿色荧光,其中构建pEGFP-N3-NOD2(1 387 bp)重组质粒经TNF-α持续刺后激绿色荧光表达最强。4段不同长度的人NOD2基因启动子绿色荧光蛋白表达载体成功构建,这为进一步研究NOD2基因表达及调控机制奠定了良好的基础。     

Toxoplasma gondii microneme protein 8 (MIC8) is a potential vaccine candidate against toxoplasmosis

Microneme protein 8 (MIC8) is considered a new essential invasion factor in Toxoplasma gondii. In the present study, a deoxyribonucleic acid vaccine expressing MIC8 of T. gondii was constructed and the immune response it induced in Kunming mice was evaluated. The gene sequence encoding MIC8 was inserted into the eukaryotic expression vector pVAX I, and the pVAX-MIC8 expression plasmid was constructed, and the plasmid diluted with PBS to l00 mg/100?µl was injected into the Kunming mice muscularly. Levels of IgG antibody, gamma-interferon (IFN-γ), interleukin-2 (IL-2), interleukin-4, and interleukin-10 were detected. The mice were challenged with tachyzoites of the virulent T. gondii RH strain at the 14th day after the last immunization to observe the survival time. The high level of IFN-γ, IL-2, and IgG antibody indicated that mice vaccinated with recombinant pVAX-MIC8 plasmid could elicit strong cellular and humoral immune responses and showed a significantly increased survival time (10.3?±?0.9 days) compared with control mice which died within 5 days of challenge infection. These data demonstrate that the T. gondii MIC8 is a potential vaccine candidate against toxoplasmosis.     

The MIC3 gene of Toxoplasma gondii is a novel potent vaccine candidate against toxoplasmosis

Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. The micronemal protein MIC3, which is a potent adhesin of T. gondii, could be a significant candidate vaccine against toxoplasmosis. In this study, all CBA/J mice intramuscularly vaccinated with a plasmid encoding the immature form of the MIC3 protein (pMIC3i) produced specific anti-MIC3 immunoglobulin G (IgG) antibodies, and their sera displayed high antibody titers. This response was increased by the coadministration of a plasmid encoding the granulocyte-macrophage colony-stimulating factor (pGM-CSF). Similarly, a specific and significant cellular immune response was obtained in mice immunized with pMIC3i, and this response was markedly enhanced by pGM-CSF coadministration. The cellular immune response was associated with the production of gamma interferon IFN-gamma and interleukin-2 (IL-2), indicating that this was a Th1-type response. This was confirmed by the production of large amounts of IgG2a. Mice immunized with pMIC3i displayed significant protection against an oral challenge with T. gondii 76K cysts, exhibiting fewer brain cysts than did the control mice. Coadministration of pGM-CSF enhanced this protection. In conclusion, this study describes the design of a potent DNA vaccine encoding the novel T. gondii target antigen, MIC3 protein, that elicits a strong specific immune response as well as providing effective protection against T. gondii infection. In the attempt to achieve complete protection against toxoplasmosis, MIC3 is a good candidate vaccine which could be combined with other relevant and previously described candidates, such as SAG1 and GRA4.     

Interactions between murine AIDS (MAIDS) and toxoplasmosis in co-infected mice.

We coinfected C57B1/6 mice with LP-BM5 murine leukaemia viruses, responsible for murine AIDS (MAIDS), and an avirulent strain of Toxoplasma gondii. Virus-infected mice were infected perorally on day 30 with 10 cysts of T. gondii, and T. gondii-infected mice were challenged with LP-BM5 on day 20, 30 or 60 after parasite inoculation. Uninfected and singly infected mice were used as controls. The kinetics of parasite burden in blood, lungs and brain, together with blood lymphocyte subsets, and spleen and lymph node weights, were serially determined in each group of mice. The kinetics of parasite counts in mice infected by LP-BM5 then by T. gondii were similar to those in mice infected by T. gondii only, except for lung counts, which reached higher values than in animals infected with T. gondii alone, then fell and re-increased until the end of the experiment. The only significant change in parasite burdens when mice were first infected by T. gondii and then by LP-BM5, compared with T. gondii controls, was an increase in lung counts in mice challenged with LP-BM5 20 days after T. gondii inoculation. Whatever the schedule of co-infection, the kinetics of lymphocyte subsets in co-infected mice differed from those in T. gondii- or LP-BM5-infected mice; in dually infected mice CD4+ and CD8+ cell counts were intermediate between values in mice singly infected by the parasite or the virus. Enlargement of spleen and lymph nodes, which is a major criterion of MAIDS progression, was significantly less marked in co-infected mice than in mice infected with LP-BM5 alone. These data point to cross-regulation of T. gondii and LP-BM5 infections, which results in increased susceptibility to T. gondii, and may alter the progression of MAIDS.     

弓形虫RH株微线体蛋白MIC3基因的克隆与表达

目的 克隆和表达弓形虫微线体蛋白MIC3基因。方法 从弓形虫RH株分离总的RNA,反转成cDNA.根据MIC3基因序列,设计合成一对引物,用聚合酶链式反应（PCR）方法从弓形虫cDNA中扩增MIC3基因片段,插入pGEM-T载体,并转化大肠杆菌Top10,经PCR、双酶切、测序验证后,将MIC3基因片段定向亚克隆到载体pET-28a中构建原核表达重组质粒pET-28a-MIC3,重组子在E.coli BL21中经IPTG诱导表达,并对表达产物进行SDS-PAGE和Western-blot分析。结果 从弓形虫RH株cDNA中扩增出792bp大小的MIC3基因片段并诱导表达27 300 Mr的重组MIC3蛋白。结论 成功构建和表达了弓形虫pET-28a-MIC3重组质粒,为弓形虫病诊断抗原和疫苗的研究奠定了基础。     

孕期弓形虫感染对小鼠胎盘补体调节蛋白表达水平的影响

目的 通过检测弓形虫感染对C57BL/6孕鼠胎盘补体调节蛋白的表达水平,探索孕期弓形虫感染致不良妊娠结局的分子免疫机制.方法 将C57BL/6孕鼠随机分为感染组和正常对照组,每组12只,感染组每只孕鼠于孕8 d腹腔注射200个弓形虫强毒株(RH株)速殖子,对照组于相应时间注射等量生理盐水.所有孕鼠均于孕14 d无菌分离胚胎组织,观察胎鼠发育情况.采用实时荧光定量PCR检测胎盘补体调节蛋白Crry、GPI-DAF及CD59a的mRNA的表达水平;采用流式细胞术检测胎盘单细胞悬液中Crry、GPI-DAF阳性细胞率.结果 弓形虫感染导致感染组死胎率显著升高(感染组死胎率为80.95%,对照组为4.41%),两组之间差异有统计学意义(P＜0.01);弓形虫感染组及对照组Crry、GPI-DAF和CD59a的mRNA表达水平分别为0.786±0.199、0.594±0.096、0.880±0.179和0.550±0.077、0.221±0.074、0.591±0.075,3类补体调节蛋白感染组与对照组比较差异均有统计学意义(P＜0.01);感染组和对照组Crry、GPI-DAF的阳性细胞百分率分别为(10.03±2.11)%、(2.95±1.04)%和(3.15±1.32)%、(0.66±0.26)%,两类补体调节蛋白感染组与对照组比较差异均有统计学意义(P＜0.01).结论 弓形虫感染导致孕鼠胎盘3种补体凋节蛋白Crry、GPI-DAF及CD59a表达水平均升高,打破了母胎界面维持正常妊娠所需的免疫微环境,这可能是孕期弓形虫感染致不良妊娠结局的分子免疫机制之一.

Abstract：

Objective To investigate the expression of complement regulatory proteins on placentas of pregnant C57BL/6 mice infected with Toxoplasma gondii in order to explore the molecular immunological mechanism for abnormal pregnancy induced by T. gondii infection. Methods Twenty-four pregnant C57BL/6 mice were randomly divided into two groups equally. The infection group was intraperitoneally injected with 200 of living T, gondii RH strain tachyzoites on the 8th day of gestation, and the normal group of mice was injected with physiological saline. All mice were killed on day 14 after gestation and placentas were collected. The expression levels of Crry, GPI-DAF and CD59a mRNA were analyzed by real-time quantitative PCR, and the positive rates of Crry and GPI-DAF were measured with flow cytometry. Results The died fetus rates of infected group and control were 80. 95% and 4. 41% , respectively. The infected group was significantly higher than of that the control group (P＜0.01). The expression levels of Crry, GPT-DAF and CD59a mRNA in the infected and control group were 0.786 ±0. 199, 0.594 ±0.096, 0.880 ±0. 179 and 0.550 ±0.077, 0.221 ±0.074, 0.591 ± 0.075 , respectively, and the difference of three kind of complement regulation proteins between two groups was all significant (P＜0.01). The positive percentages of Crry and GPI-DAF cells of infected and control group were (10. 03 ± 2. 11) % , (2.95 ±1.04)% and (3. 15 ± 1. 32) % , (0. 66 ±0. 26) % , respectively, and the difference of the two kind complement regulation proteins between two groups was also significant ( P ＜ 0. 01). Conclusion The expression level of mouse placental complement regulatory proteins was increased after infection with T. gondii, and then immunological microenvironment at the fetomaternal interface was destroyed. It may be one of important immunological mechanism for abnormal pregnancy induced by T. gondii infection.     

A GRA1 DNA vaccine primes cytolytic CD8(+) T cells to control acute Toxoplasma gondii infection

Protective immunity against Toxoplasma gondii is known to be mediated mainly by T lymphocytes and gamma interferon (IFN-gamma). The contribution of CD4(+) and CD8(+) T-lymphocyte subsets to protective immune responses against T. gondii infection, triggered by a GRA1 (p24) DNA vaccine, was assessed in this study. In vitro T-cell depletion experiments indicated that both CD4(+) and CD8(+) T-cell subsets produced IFN-gamma upon restimulation with a T. gondii lysate. In addition, the GRA1 DNA vaccine elicited CD8(+) T cells that were shown to have cytolytic activity against parasite-infected target cells and a GRA1-transfected cell line. C3H mice immunized with the GRA1 DNA vaccine showed 75 to 100% protection, while 0 to 25% of the mice immunized with the empty control vector survived challenge with T. gondii cysts. In vivo T-cell depletion experiments indicated that CD8(+) T cells were essential for the survival of GRA1-vaccinated C3H mice during the acute phase of T. gondii infection, while depletion of CD4(+) T cells led to an increase in brain cyst burden during the chronic phase of infection.     

Complete protection against lethal Toxoplasma gondii infection in mice immunized with a plasmid encoding the SAG1 gene

Infection with the protozoan parasite Toxoplasma gondii is transmitted to humans from infected animals by tissue cysts and oocysts excreted by cats. Immunization with inactivated parasites or recombinant proteins has at best shown partial protection. We constructed a plasmid expressing the SAG1 surface antigen of T. gondii, p1tPASAG1, and showed that animals immunized with the plasmid produce anti-SAG1 antibodies which recognize the native SAG1. Mice immunized with p1tPASAG1 showed 80 to 100% protection against challenge with the non-cyst-producing, virulent RH isolate, compared to an 80% mortality in mice immunized with empty plasmid, which is the greatest efficacy of any vaccine against T. gondii produced so far. The SAG1 molecule was analyzed for potential cytotoxic T-lymphocyte (CTL) epitopes, and four peptides with the best fit were synthesized. The ability of the peptides to stimulate gamma interferon production by CD8(+) T cells from p1tPASAG1-immunized mice was tested in an ELISPOT assay, and one new CTL epitope was identified. Adoptive transfer of CD8(+) T cells from p1tPASAG1-immunized to na?ve mice showed partial protection. In conclusion, DNA vaccination with p1tPASAG1 gave effective protection in mice against T. gondii infection and the protection could be adoptively transferred by purified CD8(+) T cells.     

CD8+ T cells are the major lymphocyte subpopulation involved in the protective immune response to Toxoplasma gondii in mice.

The ability of the major T cell subsets to adoptively transfer resistance to T. gondii infection was studied. Spleen cells harvested from mice with a 3-month T. gondii infection and cells from uninfected mice were enriched for T cells by nylon/wool purification. Adoptive transfer of these cells from both groups of donor mice led to a significant increase in the survival of syngeneic recipient mice infected intraperitoneally with 20 T. gondii cysts. Increased survival was mediated particularly by CD4-depleted but also, to a lesser extent, CD8-depleted subpopulations. These results were confirmed in T cell reconstituted athymic nude mice. Unfractionated T cells from chronically infected donors produced a significant inhibition of cyst formation in the brains of recipient mice measured 10 weeks after infection compared with control mice. The inhibition of cyst formation was ablated by pretreating T cells with anti-CD8 antibody and complement, but not anti-CD4 antibody and complement. Mice receiving cells from infected donors produced an early increase in their IgG1 and IgG2a antibody titres compared with mice given cells from uninfected animals. The depletion of either CD8+ or CD4+ immune cells appeared to have little effect on the antibody responses in recipient mice and there was no correlation between antibody levels and immunity. The results indicate that CD8+ T lymphocytes from convalescent T. gondii-infected BALB/c mice are the principal mediators of resistance to T. gondii, although CD4+ T cells appear to be involved during the acute phase of infection.     

Induction of human gamma interferon by structurally defined polypeptide fragments of group A streptococcal M protein.

Antigens of Toxoplasma gondii eluted from polyacrylamide gels after electrophoresis under reducing conditions were examined for their capacity to react with antibodies from infected humans, to induce antibody formation, and to protect mice against T. gondii. Antigens with approximate molecular weights of 35,000 and 14,000 strongly reacted in an enzyme-linked immunosorbent assay of human immunoglobulin M (IgM) and IgG antibodies to T. gondii. Mice injected with the eluted antigen preparations formed antibodies that reacted differently in four serological tests for Toxoplasma antibodies. All mice formed antibodies that reacted in the IgG and IgM enzyme-linked immunosorbent assay. Antibodies reacting in the conventional indirect immunofluorescent antibody test were detected in all mice except those injected with low-molecular-weight (14,000 or less) antigens. Sabin-Feldman dye test antibodies were not detected in any of the mice. Antibodies reacting in the latex agglutination test were detected mainly in mice injected with antigens with an approximate molecular weight of 66,000. Challenge of the injected mice with a lethal inoculum of T. gondii revealed that the highest survival rate was in animals that received antigens with approximate molecular weights of 35,000 and 14,000.     

Infection of mice with Neospora caninum (Protozoa: Apicomplexa) does not protect against challenge with Toxoplasma gondii.

Neospora caninum and Toxoplasma gondii are structurally related protozoal parasites of mammals that may cause abortion and neonatal morbidity and mortality. Groups of mice were subcutaneously inoculated with 10(5) live zoites of the NC-1 or NC-3 isolates of N. caninum and reinoculated with an identical number of live zoites 2 weeks later. Groups of mice which were injected subcutaneously with Hanks balanced salt solution served as controls. Three weeks after the final N. caninum inoculation, one-half of the mice were inoculated subcutaneously with 2.5 x 10(4) zoites of the RH isolate of T. gondii and the other half were inoculated subcutaneously with 2.5 x 10(4) zoites of the GT-1 isolate of T. gondii. Serum samples taken from mice on the day of T. gondii inoculation were negative for specific antibodies to T. gondii, but mice inoculated with N. caninum had reciprocal titers of greater than or equal to 800 to this protozoan. All of the mice died after challenge with T. gondii, and no significant differences (P greater than 0.05) between the survival times of mice inoculated with either isolate of N. caninum and those of control mice were seen. This study indicates that N. caninum and T. gondii are distinct biologic entities and not closely related isolates.