Intranasal immunisation with recombinant Toxoplasma gondii uridine phosphorylase confers resistance against acute toxoplasmosis in mice.

Toxoplasmosis is caused by Toxoplasma gondii, which infects all warm-blooded animals, including humans. Currently, control measures for T. gondii infection are insufficient due to the lack of effective medications or vaccines. In this paper, recombinant T. gondii uridine phosphorylase (rTgUPase) was expressed in Escherichia coli and purified via Ni2+-NTA agarose. rTgUPase was inoculated intranasally into BALB/c mice, and the induced immune responses were evaluated by mucosal and humoral antibody and cytokine assays and lymphoproliferative measurements. Moreover, the protective effect against the T. gondii RH strain infection was assessed by calculating the burdens of tachyzoites in the liver and brain and by recording the survival rate and time. Our results revealed that mice immunised with 30 µg rTgUPase produced significantly higher levels of secretory IgA (sIgA) in nasal, intestinal, vaginal and vesical washes and synthesised higher levels of total IgG, IgG1 and, in particular, IgG2a in their blood sera. rTgUPase immunisation increased the production of IFN-gamma, interleukin IL-2 and IL-4, but not IL-10 from isolated mouse spleen cells and enhanced splenocyte proliferation in vitro. rTgUPase-inoculated mice were effectively protected against infection with the T. gondii RH strain, showing considerable reduction of tachyzoite burdens in liver and brain tissues after 30 days of infection, and a 44.29% increase in survival rate during an acute challenge. The above findings show that intranasal inoculation with rTgUPase provoked mucosal, humoral and cellular immune responses and indicate that rTgUPase might serve as a promising vaccine candidate for protecting against toxoplasmosis.

Title: L'immunisation intranasale avec l'uridine phosphorylase recombinante de Toxoplasma gondii confère une résistance contre la toxoplasmose aiguë chez la souris. Abstract: La toxoplasmose est causée par Toxoplasma gondii, qui infecte tous les animaux à sang chaud, y compris les humains. Actuellement, les mesures de contrôle de l'infection à T. gondii sont insuffisantes en raison du manque de médicaments ou de vaccins efficaces. Dans cet article, l'uridine phosphorylase recombinante de T. gondii (rTgUPase) a été exprimée dans Escherichia coli et purifiée via de l'agarose Ni2+-NTA. La rTgUPase a été inoculée par voie intranasale à des souris BALB/c et les réponses immunitaires induites ont été évaluées par des dosages d'anticorps et de cytokines muqueuses et humorales et par des mesures de lymphoprolifération. De plus, l'effet protecteur contre l'infection par la souche RH de T. gondii a été évalué en calculant la charge de tachyzoïtes dans le foie et le cerveau et en enregistrant le taux et la durée de survie. Nos résultats ont révélé que les souris immunisées avec 30 µg de rTgUPase produisaient des taux significativement plus élevés d'IgA sécrétoires (sIgA) dans les lavages nasaux, intestinaux, vaginaux et vésicaux et synthétisaient des taux plus élevés d'IgG totales, d'IgG1 et, en particulier, d'IgG2a dans leur sérum sanguin. L'immunisation par la rTgUPase a augmenté la production d'IFN-gamma, d'interleukine IL-2 et IL-4, mais pas d'IL-10 à partir de cellules de rate de souris isolées et a amélioré la prolifération des splénocytes in vitro. Les souris inoculées par la rTgUPase ont été efficacement protégées contre l'infection par la souche RH de T. gondii, montrant une réduction considérable de la charge de tachyzoïtes dans les tissus hépatiques et cérébraux après 30 jours d'infection et une augmentation de 44,29 % du taux de survie lors d'une épreuve aiguë. Les résultats ci-dessus montrent que l'inoculation intranasale de rTgUPase provoque des réponses immunitaires muqueuses, humorales et cellulaires et indiquent que la rTgUPase pourrait servir de candidat vaccin prometteur pour la protection contre la toxoplasmose.

Matrix metalloproteinase-9 overexpression in the hippocampus reduces alcohol-induced conditioned-place preference by regulating synaptic plasticity in mice.

Extracellular matrix proteins appear to be necessary for the synaptic plasticity that underlies addiction memory. In the brain, matrix metalloproteinases (MMPs), especially matrix metalloproteinase-9 (MMP-9), have been recently implicated in processes involving alcohol reward and memory. Here, we showed for the first time, the positive effects of MMP-9 on alcohol-induced conditioned place preference (CPP) behavior and hippocampal neuron plasticity in C57BL/6 mice. Using recombinant adeno-associated viruses to overexpress MMP-9 in the hippocampus, we investigated the NMDAR, PSD-95, and cellular cytoskeleton proteins F-actin/G-actin in the modulation of alcohol reward behavior in mice exposed to CPP. We found that hippocampal infusions of MMP-9 decreased alcohol-induced place preference suggesting a reduction in alcohol reward. Western blot analysis demonstrated that protein expression of NMDA receptors (GluN1, GluN2A and GluN2B) in the hippocampus of alcohol-exposed mice were higher than that of the saline group. Further, the expression of these proteins was decreased in MMP-9 overexpressing mice. MMP-9 also regulated the ratio of F-actin/G-actin (dendritic spines cytoskeleton proteins), which might be the key mediator for behavioral changes in mice. Consequently, our results highlight new evidence that MMP-9 may play an important role in the molecular mechanism underlying alcohol reward and preference.

[Effects of Synaptotagmin1 gene knockout on the behavior of mice].

Objective: To study the effects of Synaptotagmin1 gene knockout (Syt1+/-) on emotional behavior in mice and explore its possible mechanisms. Methods: Five 8-week-old male Syt1+/-mice and five wild-type (WT) mice in the same litter were selected. The expressions of Syt1 in 6 mice brain regions of prelimbic cortex (PL), hippocampus (HIP), amygdala (AMY), accumbens nucleus (ACB), caudoputamen (CP) and ventral tegmental area (VTA) were detected by Immunofluorescence staining. Nine 8-week-old male Syt1+/-mice and ten WT mice were selected as controls. The anxiety-like behaviors of adult Syt1+/- mice and WT mice were detected by open field test, elevated plus maze test and forced swim test. In addition, five 8-week-old male Syt1+/-mice and five WT mice were selected to detect the glutamate content in prelimbic cortex, hippocampus and amygdala. Results: Compared with WT mice, the number of Syt1 positive cells in PL, HIP, AMY, ACB, CP and VTA were decreased significantly in Syt1+/- mice (P＜0.01); Syt1+/- mice had less total movement distance in open field test (P＜0.01), more preference for peripheral area (P＜0.01) and less desire to explore the central platform (P＜0.01), while Syt1+/- mice preferred to stay in a closed and safe environment (P＜0.01); the number (P＜0.05) and the time spent in open-arm explorations (P＜0.01) were reduced significantly; the immobile time of Syt1+/- mice was increased in the forced swim test (P＜0.01). Meanwhile, the concentration of glutamate in the amygdala of Syt1+/- mice was increased significantly (P＜0.01). Conclusion: Syt1 gene knockout leads to significant anxiety-like behavior in mice, which is deduced that related to the increase of glutamate content in the amygdala.

Activation of peripheral group III metabotropic glutamate receptors suppressed formalin-induced nociception.

Intraplantar injection of formalin produces persistent spontaneous nociception and hyperalgesia. The underlying mechanism, however, remains unclear. The present study was, therefore, designed to determine the roles of peripheral group III metabotropic glutamate receptors (mGluRs) in formalin-evoked spontaneous nociception. Pre-treatment with intraplantar injections of L-serine-O-phosphate (L-SOP), a group III mGluRs agonist, significantly inhibited formalin-induced nociceptive behaviours and decreased Fos production in the spinal dorsal horn. The inhibitory effects of L-SOP were abolished completely by pre-treatment with the group III mGluR antagonist (RS)-a-methylserine-O-phosphate (M-SOP). These data suggest that the activation of group III mGluRs in the periphery may play a differential role in formalin-induced nociception. In addition, L-SOP decreased the formalin-induced upregulation of tumour necrosis factor-α (TNF-α) as well as interleukine-1ß (IL-1ß) expression in the spinal cord, suggesting that activation of peripheral group III mGluRs reduces formalin-induced nociception through inhibition of the pro-inflammatory cytokines in the spinal cord. Therefore, the agonists acting peripheral group III mGluRs possess therapeutic effectiveness in chronic pain.

Matrix Metalloproteinase-9 Overexpression Regulates Hippocampal Synaptic Plasticity and Decreases Alcohol Consumption and Preference in Mice.

Brain matrix metalloproteinases (MMPs) have been recently implicated in alcohol addiction; however, the molecular mechanisms remain poorly understood. Matrix metalloproteinase-9 (MMP-9), an extrasynaptic protease, is the best described MMP that is thought to regulate addictive behavior. In the present study, the effect of MMP-9 overexpression on hippocampal neuron plasticity and alcoholic behavior was assessed in spontaneous alcohol drinking mice. Two-bottle choice model showed that the overexpression of MMP-9 in the hippocampus developed by adeno-associated virus (AAV) could decrease alcohol consumption and preference, but did not affect taste preference, which was tested using saccharin or quinine solutions. Dendritic spines number of hippocampal neurons was observed by Golgi staining. Compared with the alcohol treatment group, the density of dendritic spines in the hippocampus of alcohol drinking mice was decreased in alcohol + MMP-9 group. Western blot analysis indicated that GluN1 expression in the hippocampus of alcohol drinking group was lower than that in the control group, while the expression of GluN1 was increased in MMP-9 overexpressing mice. MMP-9 also regulated the depolymerization of actin filaments, which induced behavioral changes in mice. Taken together, overexpression of MMP-9 in the hippocampal neurons of mice resulted in decreased dendritic spine density and F-actin/G-actin ratio, which might be the crucial reason for the significant decrease in alcohol consumption in alcohol drinking mice. MMP-9 might be considered as a novel target studying the molecular mechanism of alcohol drinking.

Recombinant Toxoplasma gondii phosphoglycerate mutase 2 confers protective immunity against toxoplasmosis in BALB/c mice.

Toxoplasmosis is one of the most widespread zoonoses worldwide. It has a high incidence and can result in severe disease in humans and livestock. Effective vaccines are needed to limit and prevent infection with Toxoplasma gondii. In this study, we evaluated the immuno-protective efficacy of a recombinant Toxoplasma gondii phosphoglycerate mutase 2 (rTgPGAM 2) against T. gondii infection in BALB/c mice. We report that the mice nasally immunised with rTgPGAM 2 displayed significantly higher levels of special IgG antibodies against rTgPGAM 2 (including IgG1, IgG2a and IgAs) and cytokines (including IFN-γ, IL-2 and IL-4) in their blood sera and supernatant of cultured spleen cells compared to those of control animals. In addition, an increased number of spleen lymphocytes and enhanced lymphocyte proliferative responses were observed in the rTgPGAM 2-immunised mice. After chronic infection and lethal challenge with the highly virulent T. gondii RH strain by oral gavage, the survival time of the rTgPGAM 2-immunised mice was longer (P < 0.01) and the survival rate (70%) was higher compared with the control mice (P < 0.01). The reduction rate of brain and liver tachyzoites in rTgPGAM 2-vaccinated mice reached approximately 57% and 69% compared with those of the control mice (P < 0.01). These results suggest that rTgPGAM 2 can generate protective immunity against T. gondii infection in BALB/c mice and may be a promising antigen in the further development of an effective vaccine against T. gondii infection.

DNA vaccination with a gene encoding Toxoplasma gondii Rhoptry Protein 17 induces partial protective immunity against lethal challenge in mice.

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that affects humans and various vertebrate livestock and causes serious economic losses. To develop an effective vaccine against T. gondii infection, we constructed a DNA vaccine encoding the T. gondii rhoptry protein 17 (TgROP17) and evaluated its immune protective efficacy against acute T. gondii infection in mice. The DNA vaccine (p3×Flag-CMV-14-ROP17) was intramuscularly injected to BALB/c mice and the immune responses of the vaccinated mice were determined. Compared to control mice treated with empty vector or PBS, mice immunized with the ROP17 vaccine showed a relatively high level of specific anti-T. gondii antibodies, and a mixed IgG1/IgG2a response with predominance of IgG2a production. The immunized mice also displayed a specific lymphocyte proliferative response, a Th1-type cellular immune response with production of IFN-γ and interleukin-2, and increased number of CD8(+) T cells. Immunization with the ROP17 DNA significantly prolonged the survival time (15.6 ± 5.4 days, P < 0.05) of mice after challenge infection with the virulent T. gondii RH strain (Type I), compared with the control groups which died within 8 days. Therefore, our data suggest that DNA vaccination with TgROP17 triggers significant humoral and cellular responses and induces effective protection in mice against acute T. gondii infection, indicating that TgROP17 is a promising vaccine candidate against acute toxoplasmosis.

Protective immunity induced by peptides of AMA1, RON2 and RON4 containing T-and B-cell epitopes via an intranasal route against toxoplasmosis in mice.

BACKGROUND: Toxoplasma gondii is a ubiquitous protozoan intracellular parasite, the causative agent of toxoplasmosis, and a worldwide zoonosis. Apical membrane antigen-1 (AMA1) and rhoptry neck protein (RON2, RON4) are involved in the invasion of T. gondii. METHODS: This study chemically synthesized peptides of TgAMA1, TgRON2 and TgRON4 that contained the T- and B-cell epitopes predicted by bioinformatics analysis. We evaluated the systemic response by proliferation, cytokine and antibody measurements as well as the mucosal response by examining the levels of antigen-specific secretory IgA (SIgA) in the nasal, vesical and intestinal washes obtained from mice after nasal immunization with single (AMA1, RON2, RON4) or mixtures of peptides (A1 + R2, A1 + R4, R2 + R4, A1 + R2 + R4). We also assessed the parasite burdens in the liver and brain as well as the survival of mice challenged with a virulent strain. RESULTS: The results showed that the mice immunized with single or mixed peptides produced effective mucosal and systemic immune responses with a high level of specific antibody responses, a strong lymphoproliferative response and significant levels of gamma interferon (IFN-γ), interleukin-2 (IL-2) and IL-4 production. These mice also elicited partial protection against acute and chronic T. gondii infection. Moreover, our study indicated that mixtures of peptides, especially the A1 + R2 mixture, were more powerful and efficient than any other single peptides. CONCLUSIONS: These results demonstrated that intranasal immunisation with peptides of AMA1, RON2 and RON4 containing T- and B-cell epitopes can partly protect mice against toxoplasmosis, and a combination of peptides as a mucosal vaccine strategy is essential for future Toxoplasma vaccine development.

Partial protective effect of intranasal immunization with recombinant Toxoplasma gondii rhoptry protein 17 against toxoplasmosis in mice.

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that infects a variety of mammals, including humans. An effective vaccine for this parasite is therefore needed. In this study, RH strain T. gondii rhoptry protein 17 was expressed in bacteria as a fusion with glutathione S-transferase (GST) and the recombinant proteins (rTgROP17) were purified via GST-affinity chromatography. BALB/c mice were nasally immunised with rTgROP17, and induction of immune responses and protection against chronic and lethal T. gondii infections were investigated. The results revealed that mice immunised with rTgROP17 produced high levels of specific anti-rTgROP17 IgGs and a mixed IgG1/IgG2a response of IgG2a predominance. The systemic immune response was associated with increased production of Th1 (IFN-γand IL-2) and Th2 (IL-4) cytokines, and enhanced lymphoproliferation (stimulation index, SI) in the mice immunised with rTgROP17. Strong mucosal immune responses with increased secretion of TgROP17-specific secretory IgA (SIgA) in nasal, vaginal and intestinal washes were also observed in these mice. The vaccinated mice displayed apparent protection against chronic RH strain infection as evidenced by their lower liver and brain parasite burdens (59.17% and 49.08%, respectively) than those of the controls. The vaccinated mice also exhibited significant protection against lethal infection of the virulent RH strain (survival increased by 50%) compared to the controls. Our data demonstrate that rTgROP17 can trigger strong systemic and mucosal immune responses against T. gondii and that ROP17 is a promising candidate vaccine for toxoplasmosis.

Intranasal immunisation of the recombinant Toxoplasma gondii receptor for activated C kinase 1 partly protects mice against T. gondii infection.

Nasal vaccination is an effective therapeutic regimen for preventing certain infectious diseases. The mucosal immune response is important for resistance to Toxoplasma gondii infection. In this study, we evaluated the immune responses elicited in BALB/c mice by nasal immunisation with recombinant T. gondii receptor for activated C kinase 1 (rTgRACK1) and their protective efficacy against T. gondii RH strain during both chronic and lethal infections. Nasal vaccination with rTgRACK1 increased the level of secretory IgA in nasal, intestinal and vesical washes, and the level of IFN-γ and IL-2 in intestinal washes, indicating that rTgRACK1 vaccination promotes mucosal immune responses. The mice immunised with rTgRACK1 also displayed increased levels of rTgRACK1-specific IgA, total IgG, IgG1 and in particular IgG2a in their blood sera, increased production of IFN-γ, IL-2 and IL-4 but not IL-10 from their isolated spleen cells, and enhanced splenocyte proliferation in vitro. rTgRACK1-vaccinated mice were effectively protected against infection with T. gondii RH strain, showing over 50% reduction of tachyzoite burdens in their liver and brain tissues during a chronic infection, and also a 45% increase in their survivals during a lethal challenge. These results indicate that rTgRACK1 might represent an intriguing immunogen for developing a mucosal vaccine against toxoplasmosis.

[Gene-cloning, expression and immunoreactivity detection of Toxoplasma gondii uridine phosphorylase].

OBJECTIVE: To predict the physicochemical properties and antigenic epitopes of Toxoplasma gondii uridine phosphorylase (TgUPase), clone, and express TgUPase gene, and analyze its immunoreactivity. METHODS: The physical and chemical characters and specific epitopes of TgUPase protein were predicted by bioinformatics software tools. Total RNA was extracted from RH strain T. gondii tachyzoites. A pair of specific primers was designed according to the open reading frame of TgUPase gene (GenBank Accession No. DQ385446.1). RT-PCR product was digested with restriction enzyme and ligated into a pET-30a(+) vector. The recombinant plasmid pET-30a(+)-TgUPase was transformed into E. coli DH5alpha and the positive clones were selected by colony PCR and confirmed by double restriction enzyme digestion and sequencing. The constructed pET-30a(+)-TgUPase was then transformed into E. coli BL21(DE3) and induced with IPTG for expression. The expression product was analyzed through SDS-PAGE followed by Coomassie blue staining. Western blotting assay with His primary antibody and human anti-T. gondii serum was used to confirm the expression of rTgU-Pase and detect its immunoreactivity. RESULTS: Bioinformatics prediction results showed that rTgUPase protein was 303 amino acids in length with a predicted molecular mass of M, 33 042.9, and this soluble protein had three potential T/B cell epitopes. The product of RT-PCR was 921 bp. Colony PCR, double restriction enzyme digestion and DNA sequencing confirmed that the recombinant plasmid pET-30a(+)-TgUPase was constructed. SDS-PAGE showed that bacteria containing recombinant plasmid pET-30a(+)-TgUPase expressed a soluble protein of His-TgUPase (about Mr 38,000) after being induced with IPTG. The recombinant protein reacted positively with His primary antibody and human anti-T. gondii serum by Western blotting analysis. CONCLUSION: The recombinant plasmid pET-30a (+)-TgUPase is constructed and the soluble rTgUPase shows immunoreactivity.

[Construction, expression and kinase function analysis of an eukaryocyte vector of rhoptry protein 17 in Toxoplasma gondii].

OBJECTIVE: To construct and express the eukaryocytic expression vector of rhoptry protein 17 of Toxoplasma gondii RH strain (TgROP17) and analyze its kinase function. METHODS: The open reading frame of TgROP17 gene was amplified from total RNA in T. gondii RH strain by RT-PCR, and cloned into p3 x Flag-CMV-14 vector to construct recombinant plasmid p3xFlag-CMV-14/TgROP17. After colony-PCR confirming, double restriction enzyme digestion and DNA sequencing, the eukaryotic expression vector p3xFlag-CMV-14/TgROP17 was transfected into HEK 293T cells. The target gene was examined by RT-PCR and the recombinant protein was detected by Western blotting. The kinase activity of TgROP17 was identified by Western blotting and its apoptotic function was assessed by flow cytometry. RESULTS: The size of RT-PCR product was 1 850 bp. The recombinant plasmid p3xFlag-CMV-14/ TgROP17 was confirmed by colony-PCR, double restriction enzyme digestion and DNA sequencing. RT-PCR and Western blotting analysis showed that TgROP17 was expressed in the p3xFlag-CMV-14/TgROPl7 transfected-HEK 293T cells rather than in mock cells. The amplified gene was with 1,850 bp and the target protein was about M, 70,000. Western blotting analysis showed that c-Jun was phosphorylated by TgROP17. Flow cytometry analysis indicated that camptothecin-induced apoptosis was inhibited by TgROP17 with an inhibition rate of 20.6% and 24.1% at 6 h and 12 h after coculture, respectively, which was higher than that of the control (P < 0.05). CONCLUSION: The eukaryotic expression vector p3xFlag-CMV-14/TgROP17 is constructed. TgROP17 has kinase activity and playes an anti-apoptosis role.

Toxoplasma gondii protein disulfide isomerase (TgPDI) is a novel vaccine candidate against toxoplasmosis.

Toxoplasma gondii is a ubiquitous protozoan parasite that can infect all warm-blooded animals, including both mammals and birds. Protein disulfide isomerase (PDI) localises to the surface of T. gondii tachyzoites and modulates the interactions between parasite and host cells. In this study, the protective efficacy of recombinant T. gondii PDI (rTgPDI) as a vaccine candidate against T. gondii infection in BALB/c mice was evaluated. rTgPDI was expressed and purified from Escherichia coli. Five groups of animals (10 animals/group) were immunised with 10, 20, 30, 40 µg of rTgPDI per mouse or with PBS as a control group. All immunisations were performed via the nasal route at 1, 14 and 21 days. Two weeks after the last immunisation, the immune responses were evaluated by lymphoproliferative assays and by cytokine and antibody measurements. The immunised mice were challenged with tachyzoites of the virulent T. gondii RH strain on the 14th day after the last immunisation. Following the challenge, the tachyzoite loads in tissues were assessed, and animal survival time was recorded. Our results showed that the group immunised with 30 µg rTgPDI showed significantly higher levels of specific antibodies against the recombinant protein, a strong lymphoproliferative response and significantly higher levels of IgG2a, IFN-gamma (IFN-γ), IL-2 and IL-4 production compared with other doses and control groups. While no changes in IL-10 levels were detected. After being challenged with T. gondii tachyzoites, the numbers of tachyzoites in brain and liver tissues from the rTgPDI group were significantly reduced compared with those of the control group, and the survival time of the mice in the rTgPDI group was longer than that of mice in the control group. Our results showed that immunisation with rTgPDI elicited a protective immune reaction and suggested that rTgPDI might represent a promising vaccine candidate for combating toxoplasmosis.

Intranasal immunisation with recombinant Toxoplasma gondii actin partly protects mice against toxoplasmosis.

Toxoplasma gondii is a ubiquitous protozoan intracellular parasite, the causative agent of toxoplasmosis, and a worldwide zoonosis for which an effective vaccine is needed. Actin is a highly conserved microfilament protein that plays an important role in the invasion of host cells by T. gondii. This study investigated the immune responses elicited by BALB/c mice after nasal immunisation with a recombinant T. gondii actin (rTgACT) and the subsequent protection against chronic and lethal T. gondii infections. We evaluated the systemic response by proliferation, cytokine and antibody measurements, and we assessed the mucosal response by examining the levels of TgACT-specific secretory IgA (SIgA) in nasal, vaginal and intestinal washes. Parasite load was assessed in the liver and brain, and the survival of mice challenged with a virulent strain was determined. The results showed that the mice immunised with rTgACT developed high levels of specific anti-rTgACT IgG titres and a mixed IgG1/IgG2a response with a predominance of IgG2a. The systemic immune response was associated with increased production of Th1 (IFN-γ and IL-2), Th2 (IL-4) and Treg (IL-10) cytokines, indicating that not only Th1-type response was induced, but also Th2- and Treg-types responses were induced, and the splenocyte stimulation index (SI) was increased in the mice immunised with rTgACT. Nasal immunisation with rTgACT led to strong mucosal immune responses, as seen by the increased secretion of SIgA in nasal, vaginal and intestinal washes. The vaccinated mice displayed significant protection against lethal infection with the virulent RH strain (survival increased by 50%), while the mice chronically infected with RH exhibited lower liver and brain parasite loads (60.05% and 49.75%, respectively) than the controls. Our data demonstrate, for the first time, that actin triggers a strong systemic and mucosal response against T. gondii. Therefore, actin may be a promising vaccine candidate against toxoplasmosis.

Gene-cloning, expression and antigenicity analysis of rhoptry protein 17 of Toxoplasma gondii.

OBJECTIVE: To clone and express the rhoptry protein 17 (ROP17) gene of RH strain of Toxoplasma gondii, analyze the antigenicity of recombinant protein. METHODS: Total RNA was extracted from tachyzoites of RH strain of T. gondii. The open reading frame of TgROP17 gene was amplified with a pair of specific primers which was designed according to the coding sequence of TgROP17 gene (GenBank accession No. AM075203.1), the product of RT-PCR was digested with double restriction enzyme and ligated into a pGEX-6P-1 vector. The recombinant pGEX-6P-1-TgROP17 plasmid was transferred into E. coli DH5alpha and the positive clones were selected through the colony-PCR and confirmed by the double restriction enzyme digestion and sequencing. The constructed pGEX-6P-1-TgROP17 was transformed into E. coli Rosetta (DE3) and induced with IPTG for expression. The expression products were analyzed through SDS-PAGE followed by Coomassie blue staining. Western blotting assay with GST primary antibody and rabbit anti-T. gondii serum was used to confirm the expression of GST-ROP17 and analyze its antigenic properties. RESULTS: The product of RT-PCR was with 1 850 bp. The recombinant plasmid pGEX-6P-1-TgROP17 was confirmed by colony-PCR, double restriction enzyme digestion and sequencing. A soluble recombinant protein with relative molecular weight of 96,000 was analyzed by SDS-PAGE followed by Coomassie blue staining. The GST tag in GST-ROP17 and the antigenicity of ROP17 were detected efficiently by Western blotting with the GST primary antibody and with the prepared antiserum against T. gondii, respectively. CONCLUSION: The recombinant GST-ROP17 protein has been produced in E. coli and shows specific antigenicity.

[Cloning, expression and antigenicity analysis of phosphoglycerate mutase 2 gene of Toxoplasma gondii].

OBJECTIVE: To clone and express the phosphoglycerate mutase 2 (PGAM2) gene of Toxoplasma gondii, and analyze the antigenicity of the recombinant protein. METHODS: Total RNA was extracted from T. gondii tachyzoites of RH strain and reversely transcribed into cDNA. TgPGAM2 gene was amplified by PCR and cloned into pET30a(+) vector. The constructed pET30a(+)-TgPGAM2 was transformed into E. coli DH5alpha first and selected through the colony-PCR and confirmed by the double restriction enzyme digestion and sequencing. The correct plasmid was transformed into E. coli BL21 for expression induced by IPTG and the recombinant protein was further analyzed through SDS-PAGE followed by Coomassie brilliant blue staining. Western blotting assay with rabbit anti-T. gondii serum was used to analyze its antigenicity. RESULTS: The length of PCR product was about 750 bp and the recombinant plasmid pET30a(+)-TgPGAM2 was successfully constructed. The results of SDS-PAGE and Western blotting revealed that the relative molecular weight (Mr) of the soluble recombinant protein was approximately 30 000 and could be recognized by rabbit anti-T. gondii serum. CONCLUSION: The soluble TgPGAM2 protein has been expressed in the prokaryotic expression system and maintains its antigenicity.

[Early kinetics of Toxoplasma gondii infection in mice infected intragastrically with tachyzoites by chromogenic in situ hybridization targeting SAG2 mRNA].

OBJECTIVE: To observe the early kinetics of Toxoplasma gondii infection in mice inoculated with tachyzoites of RH strain. METHODS: Twenty BALB/c mice were administered intragastrically with tachyzoites of RH strain (2 x 10(4)/mice). Parasite burdens in mesenteric lymph node (MLN), liver, spleen, lung and brain were determined by chromogenic in situ hybridization targeting SAG2 mRNA at 1, 2, 4, 6 and 8 days postinfection. Five mice were inoculated with PBS as blank control. RESULTS: The MLN, liver and spleen were the first organs where tachyzoites were found on the first day after infection, followed by the lungs on the 4th day and the brain on the 6th day. On days 6 to 8 after infection, there was a significant difference on parasite load among the tissues (P < 0.05), and the parasite load in MLN was highest, followed by that of liver, spleen, lungs and brain. The number of tachyzoites in various tissues was time-dependent. CONCLUSION: T. gondii tachyzoites were first detected in MLN, liver and spleen, then in the lungs, and finally in the brain. The number of tachyzoites in the MLNs increased more rapidly.

[Kinetics of IgA secreting cells and sIgA in small intestine of mice induced by intranasal immunization with Toxoplasma gondii STAg].

OBJECTIVE: To investigate the kinetics of IgA secreting cells (IgASCs) and secretory IgA (sIgA) level in small intestine induced by intranasal immunization with Toxoplasma gondii soluble tachyzoite antigen (STAg) in mice. METHODS: Ninety-six 5 to 6-week old BALB/c mice were randomly divided into immunity and control groups. Mice of the immunity group were each intranasally immunized with STAg 20 microg in 20 microl PBS, twice at an interval of 2 weeks, while the control mice were each given 20 microl PBS. All mice were challenged intragastrically with 1 x 10(4) tachyzoites in 0.5 ml per mouse in 1 week after the last immunization. The body weight and infection incidence of mice were recorded. Eight mice of each group were sacrificed on the day 6, 7, 8, 9, 10 and 11 post infection, respectively. The quantity of IgASCs in mucosa of duodenum, jejunum and ileum was detected by immunohistochemistry. The sIgA in intestinal washes were determined by ELISA. RESULTS: All mice fell ill post infection, but the symptom of mice in the immunity group was milder, the increasing level of body weight of mice in the immunity group was higher considerably than that in the control group (P < 0.05). Two mice died in control group on the 7th day after infection. sIgA level in intestinal washes increased continually in two groups, but the increasing level in the immunity group was higher than that of the control (P < 0.05). The number of IgASCs in duodenum increased slightly in the control group, but increased continuously and maintained a high level after 9 d in the immunity group, for instance, 20.65 +/- 1.67 in the immunity group and 12.30 +/- 2.67 in the control. The correlation of the sIgA level in intestinal washes and the quantitative change of IgASCs in duodenum was positive in the immunity group (r = 0.566, P < 0.05) and the control (r = 0.378, P < 0.05). The number of IgASCs in jejunum decreased in the control group but increased then slightly decreased after 9 d in the immunity group. Positive correlation between the sIgA level in intestinal washes and the quantitative change of IgASCs in jejunum was found in the immunity group (r = 0.218, P > 0.05) but negative in the control (r = -0.557, P < 0.05). The number of IgASCs in ileum declined in the control group but maintained a high level in the immunity group. The correlation between the sIgA level in intestinal washes and the quantitative change of IgASCs in ileum was r = -0.053 (P > 0.05) in the immunity group and r = -0.685 (P < 0.05) in the control. CONCLUSION: Intranasal immunization with STAg in mice orally infected with Toxoplasma gondii can increase the number of IgASCs in jejunum and ileum, and enhance the immune barrier function of mucosa in small intestine of mice.

Potential adenovirus-mediated gene therapy of glioma cancer.

Malignant gliomas are typically characterized by rapid cell proliferation and a marked propensity to invade and damage surrounding tissues. They are the main brain tumors notoriously resistant to currently available therapies, since they fail to undergo apoptosis upon anticancer treatments. With recent advances in neuroscience and improved understanding of the molecular mechanisms of invasive migration, gene therapy provides a new strategy for treating glioma cancer. Brain tumor gene therapy using viral vectors and stem cells has shown promise in animal model and human patient studies. Here, we review recent studies on engineering adenoviral vectors that can be used as therapy for brain tumors. The new findings presented in this study are essential for the further exploration of this cancer and they represent an approach for developing a newer and more effective therapeutic approach in the clinical treatment of human glioma cancer.

Potential biochemical therapy of glioma cancer.

Glioma is a highly invasive, rapidly spreading form of brain cancer that is resistant to surgical and medical treatment. The recent progresses made in intracellular and ion channels of glioma cells provide a potential new approach for biochemical therapy of brain tumor. In this paper, we reviewed clinical data on chemotherapy by temozolomide and results from new studies on voltage-gated potassium channels, large-conductance Ca(2+)-activated K(+) channels, volume-activated chloride channels, glioma-specific chloride channel and their modulators. These new findings may represent future directions for brain tumor studies and treatment.