Protective efficacy of recombinant Toxoplasma gondii dense granule protein 15 against toxoplasmosis in C57BL/6 mice

Toxoplasma gondii is a pervasive protozoan parasite that is responsible for significant zoonoses. A wide array of vaccines using different effector molecules of T. gondii have been studied worldwide to control toxoplasmosis. None of the existing vaccines are sufficiently effective to confer protective immunity. Among the different Toxoplasma-derived effector molecules, T. gondii dense granule protein 15 from the type II strain (GRA15 (II)) was recently characterized as an immunomodulatory molecule that induced host immunity via NF-κB. Therefore, we assessed the immunostimulatory and protective efficacy of recombinant GRA15 (II) (rGRA15) against T. gondii infection in a C57BL/6 mouse model. We observed that rGRA15 treatment increased the production of IL-12p40 from mouse peritoneal macrophages in vitro. Immunization of mice with rGRA15 induced the production of anti-TgGRA15-specific IgG, IgG1 and IgG2c antibodies. The rGRA15-sensitized spleen cells from mice inoculated with the same antigen strongly promoted spleen cell proliferation and IFN-γ production. Immunization with rGRA15 significantly enhanced the survival rate of mice and dramatically decreased parasite burden in mice challenged with the Pru (type II) strain. These results suggested that rGRA15 triggered humoral and cellular immune responses to control infection. However, all of the immunized mice died when challenged with the GRA15-deficient Pru strain or the RH (type I) strain. These results suggest that GRA15 (II)-dependent immunity plays a crucial role in protection against challenge infection with the type II strain of T. gondii. This study is the first report to show GRA15 (II) as a recombinant vaccine antigen against Toxoplasma infection.

Cross-sectional community-based study to assess the awareness of toxoplasmosis in Saudi Arabia

A few reports have been published and documented low level of awareness on toxoplasmosis among Saudi women. Herein, a cross sectional community based study was undertaken to evaluate basic knowledge on toxoplasmosis among residents in the Eastern province (Sharqiyah). Thisstudy was conducted between December 2022 and January 2023 on 334 females from different ages and educational backgrounds. Analysis of their responses revealed that only (24.9%) had heard about the disease. However, (69.8%) properly identified cats as the source of Toxoplasma gondii (T. gondii), but a smaller percentage (47.7%) knew that they might become infected through handling cat feces, and a few (26.3%) believed that bad hand hygiene can result in T. gondii infection. A few males (n = 26) have also participated, for the first time in Saudi Arabia, and displayed also low level of knowledge on toxoplasmosis. We do recommend establishing educational programs for females, in various Saudi provinces, to raise awareness on toxoplasmosis.

Protective effect against toxoplasmosis in BALB/C mice vaccinated with recombinant Toxoplasma gondii CDPK3, GRA35, and ROP46 protein cocktail vaccine

Toxoplasma gondii (T. gondii) is one of the most common pathogenic protozoa in the world, and causes toxoplasmosis, which in varying degrees causes significant economic losses and poses a serious public health challenge globally. To date, the development of an effective vaccine for human toxoplasmosis remains a challenge. Given that T.gondii calcium-dependent protein kinase 3 (CDPK3), dense granule protein 35 (GRA35) and rhoptry organelle protein 46 (ROP46) play key roles during Toxoplasma gondii invasion of host cells, we developed a protein vaccine cocktail including these proteins and validated its protective efficacy. The specific protective effects of vaccine on mice were analyzed by measuring serum antibodies, cytokines, splenocyte proliferation, the percentage of CD4+ and CD8+ T-lymphocytes, survival rate, and parasite cyst burden. The results showed that mice vaccinated with a three-protein cocktail produced the highest levels of immune protein antibodies to IgG, and high levels of IFN-γ, IL-2, IL-4, and IL-10 compared to other mice vaccinated with two proteins. In addition, CD4+ and CD8+ T cell percentages were significantly elevated. Compared to the control groups, mice vaccinated with the three-protein cocktail survived significantly longer after acute infection with T. gondii and had significantly fewer cysts after chronic infection. These results demonstrated that a cocktail vaccine of TgCDPK3, TgGRA35, and TgROP46 can effectively induce cellular and humoral immune responses with good protective effects in mice, indicating its potential as vaccine candidates for toxoplasmosis.

Comparison of the immune response and protection against the experimental Toxoplasma gondii infection elicited by immunization with the recombinant proteins BAG1, ROP8, and BAG1-ROP8

Toxoplasmosis is one of the most dangerous zoonotic diseases, causing serious economic losses worldwide due to abortion and reproductive problems. Vaccination is the best way to prevent disease; thus, it is imperative to develop a candidate vaccine for toxoplasmosis. BAG1 and ROP8 have the potential to become vaccine candidates. In this study, rTgBAG1, rTgROP8, and rTgBAG1-rTgROP8 were used to evaluate the immune effect of vaccines in each group by detecting the humoral and cellular immune response levels of BABL/c mice after immunization and the ability to resist acute and chronic infection with Toxoplasma gondii (T. gondii). We divided the mice into vaccine groups with different proteins, and the mice were immunized on days 0, 14, and 28. The protective effects of different proteins against T. gondii were analysed by measuring the cytokines, serum antibodies, splenocyte proliferation assay results, survival time, and number and diameter of brain cysts of mice after infection. The vaccine groups exhibited substantially higher IgG, IgG1, and IgG2a levels and effectively stimulated lymphocyte proliferation. The levels of IFN-γ and IL-2 in the vaccine group were significantly increased. The survival time of the mice in each vaccine group was prolonged and the diameter of the cysts in the vaccine group was smaller; rTgBAG1-rTgROP8 had a better protection. Our study showed that the rTgBAG1, rTgROP8, and rTgBAG1-rTgROP8 recombinant protein vaccines are partial but effective approaches against acute or chronic T. gondii infection. They are potential candidates for a toxoplasmosis vaccine.

A novel mRNA vaccine, TGGT1_278620 mRNA-LNP, prolongs the survival time in BALB/c mice with acute toxoplasmosis

IMPORTANCE

Toxoplasma gondii, an obligate intracellular eukaryotic parasite, can infect about one-third of the world's population. One vaccine, Toxovax, has been developed and licensed commercially; however, it is only used in the sheep industry to reduce the losses caused by congenital toxoplasmosis. Various other vaccine approaches have been explored, including excretory secretion antigen vaccines, subunit vaccines, epitope vaccines, and DNA vaccines. However, current research has not yet developed a safe and effective vaccine for T. gondii. Here, we generated an mRNA vaccine candidate against T. gondii. We investigated the efficacy of vaccination with a novel identified candidate, TGGT1_278620, in a mouse infection model. We screened T. gondii-derived protective antigens at the genome-wide level, combined them with mRNA-lipid nanoparticle vaccine technology against T. gondii, and investigated immune-related factors and mechanisms. Our findings might contribute to developing vaccines for immunizing humans and animals against T. gondii.

Protective efficacy of Toxoplasma gondii infected cells-derived exosomes against chronic murine toxoplasmosis

Exosomes were isolated from T. gondii infected human hepatoblastoma cells using the exosome isolation kit and characterized by electron microscopy and Western blotting. Exosomes adsorbed to alum adjuvant were evaluated as a potential immunizing agent against murine chronic toxoplasmosis compared to excretory secretory antigens (ESA)-alum. Mice were immunized at days 1, 15 and 29. The levels of IgG, IFN-γ, IL-4 and IL-10, CD4+ and CD8+ T cells were determined using sandwich enzyme-linked immunosorbent assay (sandwich ELISA) at days 14, 28 and 56 of the experiment. Then mice were infected orally with 10 cysts of T. gondii. The protective efficacy of the antigens were evaluated by counting the brain cysts and measuring the aforementioned humoral and cellular parameters 60 days post infection. The results showed that alum increased the protective efficacy of the exosomes. Immunization with exosome-alum induced both humoral and mixed Th1/Th2 cellular immune responses. Exosome-alum gave higher levels of the humoral and cellular parameters, compared to ESA-alum. After challenge infection, exosome-alum significantly reduced the brain cyst burden by 75 % while ESA-alum gave 42 % reduction and evoked higher humoral and cellular immune responses. Therefore, the possibility of using T. gondii infected cells-derived exosome-alum as a vaccine is a new perspective in toxoplasmosis.

Identification of specific antigens between Toxoplasma gondii and Neospora caninum and application of potential diagnostic antigen TgGRA54

Toxoplasma gondii is a zoonotic parasite that is very common in livestock. Meat products from livestock infected with T. gondii are one of the important transmission routes of toxoplasmosis. Rapid and reliable diagnosis is a prerequisite for the prevention and control of toxoplasmosis. Neospora caninum and T. gondii are similar in morphology and life history, and there are a large number of cross antigens between them, making clinical diagnosis of toxoplasmosis more difficult. In this study, immunoprecipitation-mass spectrometry (IP-MS) was used to screen for T. gondii-specific antigens, and the specific antigen was cloned and expressed in Escherichia coli. The specific antigen was then used to establish an indirect ELISA diagnostic method. A total of 241 specific antigens of T. gondii and 662 cross antigens between T. gondii and N. caninum were screened by IP-MS. Through bioinformatics analysis and homology comparison, seven proteins were selected for gene cloning and prokaryotic expression, and the most suitable antigen, TgGRA54, was selected to establish an indirect ELISA for T. gondii. Compared with the indirect immunofluorescent antibody test (IFAT), the positive coincidence rate of the ELISA based on rTgGRA54 was 100% (72/72) and the negative coincidence rate was 80.95% (17/21). The indirect ELISA method based on TgGRA54 recombinant protein was established to detect T. gondii antibodies in bovine sera, and the recombinant protein reacted well with T. gondii positive sera from sheep, mouse, and swine, indicating that the recombinant protein is a good diagnostic antigen for T. gondii.

[Bioinformatics analysis of the RNA binding protein DDX39 of Toxoplasma gondii]

OBJECTIVE

To analyze the RNA binding protein of Toxoplasma gondii (TgDDX39) using bioinformatics technology, and to evaluate the immunogenicity of TgDDX39, so as to provide insights into development of toxoplasmosis vaccines.

METHODS

The amino acid sequences of TgDDX39 were retrieved from the ToxoDB database, and the physicochemical properties, transmembrane structure domain, signal peptide sites, post-translational modification sites, coils, secondary and tertiary structures, hydrophobicity, and antigenic epitopes of the TgDDX39 protein were predicted using online bioinformatics tools, incluiding ProtParam, TMHMM 2.0, SignalP 5.0, NetPhos 3.1, COILS, SOPMA, Phyre2, ProtScale, ABCpred, SYFPEITHI and DNA-STAR.

RESULTS

TgDDX39 protein was predicted to be an unstable hydrophilic protein with the molecular formula of C2173H3458N598O661S18, which contained 434 amino acids and had an estimated molecular weight of 49.1 kDa and a theoretical isoelectric point of 5.55. The protein was predicted to have an extremely low possibility of signal peptides, without transmembrane regions, and contain 27 phosphorylation sites. The β turn and random coils accounted for 39.63% of the secondary structure of the TgDDX39 protein, and a coiled helix tended to produce in one site. In addition, the TgDDX39 protein contained multiple B and T cell antigenic epitopes.

CONCLUSIONS

Bioinformatics analyses predict that TgDDX39 protein has high immunogenicity and contains multiple antigenic epitopes. TgDDX39 protein is a potential candidate antigen for vaccine development.

Recent progress in vaccine development targeting pre-clinical human toxoplasmosis

Toxoplasma gondii is an intracellular parasitic organism affecting all warm-blooded vertebrates. Due to the unavailability of commercialized human T. gondii vaccine, many studies have been reported investigating the protective efficacy of pre-clinical T. gondii vaccines expressing diverse antigens. Careful antigen selection and implementing multifarious immunization strategies could enhance protection against toxoplasmosis in animal models. Although none of the available vaccines could remove the tissue-dwelling parasites from the host organism, findings from these pre-clinical toxoplasmosis vaccine studies highlighted their developmental potential and provided insights into rational vaccine design. We herein explored the progress of T. gondii vaccine development using DNA, protein subunit, and virus-like particle vaccine platforms. Specifically, we summarized the findings from the pre-clinical toxoplasmosis vaccine studies involving T. gondii challenge infection in mice published in the past 5 years.

Immunogenic evaluation of multi-epitope peptide-loaded PCPP microparticles as a vaccine candidate against Toxoplasma Gondii

Toxoplasmosis is a major health problem and socioeconomic burden, affecting around 30-50% of the global population. Poly(dicarboxylatophenoxy)phosphazene (PCPP) polymer was chosen as adjuvant for the immunogenic peptide antigen. Peptide-loaded PCPP microparticles were synthesized via the coacervation method and the characterization studies of microparticles were conducted to determine their size, charge, morphology, encapsulation efficacy, and loading capacity. To evaluate in vivo efficacy of the vaccine candidate, Balb/c mice were immunized with the formulations. Brain and spleen tissues were isolated from animals to investigate cytokine levels, lymphocyte proliferation, and brain cyst formation. As a result, antibody and cytokine responses in groups immunized with peptide-loaded PCPP microparticles were found to be significantly higher when compared to the control group. In conclusion, our novel multi-epitope peptide-loaded PCPP microparticle-based vaccine formulation demonstrated considerable humoral and cellular immune responses against T. gondii and protected mice against T. gondii infection during Toxoplasmosis.

Toxoplasma gondii vaccine candidates: a concise review

Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis. It has been shown that the severity of symptoms depends on the functioning of the host immune system. Although T. gondii infection typically does not lead to severe disease in healthy people and after infection, it induces a stable immunity, but it can contribute to severe and even lethal Toxoplasmosis in immunocompromised individuals (AIDS, bone marrow transplant and neoplasia). The antigens that have been proposed to be used in vaccine candidate in various studies include surface antigens and secretory excretions that have been synthesized and evaluated in different studies. In some studies, secretory antigens play an important role in stimulating the host immune response. Various antigens such as SAG, GRA, ROP, ROM, and MAG have been from different strains of T. gondii have been synthesized and their protective effects have been evaluated in animal models in different vaccine platforms including recombinant antigens, nanoparticles, and DNA vaccine. Four bibliographic databases including Science Direct, PubMed Central (PMC), Scopus, and Google Scholar were searched for articles published up to 2020.The current review article focuses on recent studies on the use and usefulness of recombinant antigens, nanoparticles, and DNA vaccines.

Prevention of congenital toxoplasmosis in France using prenatal screening: A decision-analytic economic model

Background

Toxoplasma gondii is one of the world’s most common parasites. Primary infection of the mother during pregnancy can lead to transmission to the fetus with risks of brain and eye lesions, which may cause lifelong disabilities. France instituted a national program based on monthly retesting of susceptible pregnant women to reduce the number of severe cases through prompt antenatal and postnatal treatment and follow-up.

Objective

To evaluate the ability of the French prenatal retesting program to reduce the lifetime costs of congenital toxoplasmosis.

Methods

We measured and then compared the costs and benefits of screening vs. not screening using decision-tree modelling. It included direct and indirect costs to society of treatment and care, and the lifetime lost earnings of children and caregivers. A probabilistic sensitivity analysis was carried out.

Findings

Total lifetime costs per live born child identified as congenitally infected were estimated to be €444 for those identified through prenatal screening vs €656 for those who were not screened. Estimates were robust to changes in all costs of diagnosis, treatment, and sequelae.

Interpretation

Screening for the prevention of the congenital T. gondii infection in France is cost saving at €212 per birth. Compared with no screening, screening every pregnant woman in France for toxoplasmosis in 2020 would have saved the country €148 million in addition to reducing or eliminating the devastating physical and emotional suffering caused by T. gondii. Our findings reinforce the conclusions of other decision-analytic modelling of prenatal toxoplasmosis screening.

The Heptaprenyl Diphosphate Synthase (Coq1) Is the Target of a Lipophilic Bisphosphonate That Protects Mice against Toxoplasma gondii Infection

Prenyldiphosphate synthases catalyze the reaction of allylic diphosphates with one or more isopentenyl diphosphate molecules to form compounds such as farnesyl diphosphate, used in, e.g., sterol biosynthesis and protein prenylation, as well as longer "polyprenyl" diphosphates, used in ubiquinone and menaquinone biosynthesis. Quinones play an essential role in electron transport and are associated with the inner mitochondrial membrane due to the presence of the polyprenyl group. In this work, we investigated the synthesis of the polyprenyl diphosphate that alkylates the ubiquinone ring precursor in Toxoplasma gondii, an opportunistic pathogen that causes serious disease in immunocompromised patients and the unborn fetus. The enzyme that catalyzes this early step of the ubiquinone synthesis is Coq1 (TgCoq1), and we show that it produces the C35 species heptaprenyl diphosphate. TgCoq1 localizes to the mitochondrion and is essential for in vitro T. gondii growth. We demonstrate that the growth defect of a T. gondii TgCoq1 mutant is rescued by complementation with a homologous TgCoq1 gene or with a (C45) solanesyl diphosphate synthase from Trypanosoma cruzi (TcSPPS). We find that a lipophilic bisphosphonate (BPH-1218) inhibits T. gondii growth at low-nanomolar concentrations, while overexpression of the TgCoq1 enzyme dramatically reduced growth inhibition by the bisphosphonate. Both the severe growth defect of the mutant and the inhibition by BPH-1218 were rescued by supplementation with a long-chain (C30) ubiquinone (UQ6). Importantly, BPH-1218 also protected mice against a lethal T. gondii infection. TgCoq1 thus represents a potential drug target that could be exploited for improved chemotherapy of toxoplasmosis. IMPORTANCE Millions of people are infected with Toxoplasma gondii, and the available treatment for toxoplasmosis is not ideal. Most of the drugs currently used are only effective for the acute infection, and treatment can trigger serious side effects requiring changes in the therapeutic approach. There is, therefore, a compelling need for safe and effective treatments for toxoplasmosis. In this work, we characterize an enzyme of the mitochondrion of T. gondii that can be inhibited by an isoprenoid pathway inhibitor. We present evidence that demonstrates that inhibition of the enzyme is linked to parasite death. In addition, the inhibitor can protect mice against a lethal dose of T. gondii. Our results thus reveal a promising chemotherapeutic target for the development of new medicines for toxoplasmosis.

PLGA Nanoparticles as an Efficient Platform in Protein Vaccines Against Toxoplasma gondii

BACKGROUND

Toxoplasma gondii (T. gondii) as an obligatory intracellular is widespread all over the world and causes considerable concerns in immunocompromised patients by developing toxoplasmic encephalitis and in pregnancy because of serious consequences in the fetus. Although vaccination is the only approach to overcome toxoplasmosis, there is no commercially available human vaccine against T. gondii.

PURPOSE

The remarkable features of poly (lactic-co-glycolic acid) (PLGA) particles have brought up the application of PLGA as a promising vaccine delivery vehicle against T. gondii and other intracellular parasites. This review focuses on the application of the PLGA delivery system in the development of preventive vaccines against T. gondii.

METHODS

In this study, all required data were collected from articles indexed in English databases, including Scopus, PubMed, Web of Science, Science Direct, and Google Scholar.

RESULT

Immunity against T. gondii, characteristics of PLGA particles as a delivery vehicle, and all researches on particulate PLGA vaccines with different T. gondii antigens and DNA against were discussed and their efficacies in conferring protection against a lethal challenge based on increased survival or reduced brain cyst loads have been shown.

CONCLUSION

Although various levels of protection against lethal challenge have been achieved through PLGA-based vaccinations, there is still no complete protection against T. gondii infection. Surprisingly, the application of surface modifications of PLGA particles by mucoadhesive polymers, cationic agents, DCs (dendritic cells) targeting receptors, specialized membranous epithelial cells (M-cells), and co-delivery of the desired antigen along with toll-like receptor ligands would be a revolutionized vaccine strategy against T. gondii.

Hygiene measures as primary prevention of toxoplasmosis during pregnancy: A systematic review

Background Hygiene measures are recommended to prevent toxoplasmosis during pregnancy, although screening for seroconversion in pregnant women currently are debated and practices vary among countries. Objectives The purpose of this systematic literature review was to assess the effectiveness of hygiene measures during pregnancy to prevent toxoplasmosis infection. Search Strategy We followed the standard MOOSE and PRISMA criteria when conducting this systematic review and reporting the results. Selection criteria A systematic literature search was conducted for studies focused on congenital toxoplasmosis prevention, toxoplasmosis prevention during pregnancy, toxoplasmosis prevention and hygiene measures, which were published between 1970 and August 2020, using the databases of PubMed, Scope Med, EMBASE, and the Cochrane library. Data collection and analysis Our literature search identified 3964 articles, 3757 were excluded after review of title or abstract and 67 studies were considered relevant to the subject. We reviewed risk factors for toxoplasmosis infection during pregnancy and for congenital toxoplasmosis, preventive measures for toxoplasmosis during pregnancy, including: dietary recommendations, pet care measures, environmental measures, knowledge of risk factors and ways to control toxoplasmosis infection, knowledge of risk factors for infection by health professionals, knowledge of primary prevention measures by pregnant women. Conclusion: Hygiene measures are effective and applicable primary prevention to reduce toxoplasmosis and avoid congenital toxoplasmosis and its consequences. Funding No.

Macrophage Stimulation as a Useful Approach for Immunoscreening of Potential Vaccine Candidates Against Toxoplasma gondii and Neospora caninum Infections

Toxoplasmosis and neosporosis are protozoan diseases that adversely affect the medical and additionally veterinary sectors, respectively. Toxoplasmosis is caused by Toxoplasma gondii which infects almost all warm-blooded animals including humans. While, neosporosis is caused by Neospora caninum, which induces infection in many animal species particularly in cattle. Currently, control measures for both infections are defective because of no effective vaccine or treatment. Macrophages constitute the first line of innate immunity, which contributes to the effective elimination of T. gondii or N. caninum. This action is mediated by IL-12, which is critical for the secretion of interferon gamma (IFN-γ). Successful vaccine candidates against both protozoan parasites should possess the ability to induce the cellular immune response and IFN-γ production. In this chapter, we will focus on an efficient immunological approach for discovery of potential vaccine candidates against above-mentioned parasites. Our previous studies revealed a strong correlation between vaccine antigens that enhanced the macrophage secretion of IL-12 and their efficacy as potential vaccine candidates in murine model. In case of T. gondii, peroxiredoxin 1 (TgPrx1) and peroxiredoxin 3 stimulated the production of IL-12 from murine peritoneal macrophages and conferred strong to moderate protection in C57BL/6 mice, respectively. At the same context, Neospora antigens of dense granule protein 6 (NcGRA6) and cyclophilin entrapped with oligo-mannose coated-liposomes stimulated macrophage IL-12 secretion and substantially protected immunized BALB/c mice. Therefore, we can deduce that macrophage stimulation evidenced in IL-12 production can be used as a useful approach for judgment of vaccine efficacy before further evaluation using in vivo experiments. Methods of vaccine preparation and macrophage stimulation will be fully described for TgPrx1 and NcGRA6 as potential vaccine candidates against toxoplasmosis and neosporosis, respectively.

Acute exacerbation of pulmonary toxoplasmosis during corticosteroid therapy for immune thrombocytopenia: A case report and literature review

RATIONALE

Pulmonary toxoplasmosis (PT) is an infectious disease that can be fatal if reactivation occurs in the recipients of hematopoietic stem cell transplantation (HSCT) who were previously infected with Toxoplasma gondii. However, whether the toxoplasmosis reactivation is an actual risk factor for patients receiving immunosuppressive therapies without HSCT remains unclear. Therefore, reactivated PT is not typically considered as a differential diagnosis for pneumonia other than in patients with HSCT or human immunodeficiency virus (HIV).

PATIENT CONCERNS

A 77-year-old man presented with fever and nonproductive cough for several days. He was hospitalized due to atypical pneumonia that worsened immediately despite antibiotic therapy. Before 4 months, he was diagnosed with immune thrombocytopenia (ITP) and received corticosteroid therapy. Trimethoprim-sulfamethoxazole (ST) was administered to prevent pneumocystis pneumonia resulting from corticosteroid therapy.

DIAGNOSIS

The serological and culture test results were negative for all pathogens except T. gondii immunoglobulin G antibody. Polymerase chain reaction, which can detect T. gondii from frozen bronchoalveolar lavage fluid, showed positive results. Therefore, he was diagnosed with PT.

INTERVENTION

ST, clindamycin, and azithromycin were administered. Pyrimethamine and sulfadiazine could not be administered because his general condition significantly worsened at the time of polymerase chain reaction (PCR) examination.

OUTCOMES

The patient died of acute respiratory distress syndrome despite anti-T. gondii treatment. An autopsy revealed a severe organizing pneumonia and a small area of bronchopneumonia.

LESSONS

PT should be considered as a differential diagnosis in patients with pneumonia, particularly in seropositive patients who receive immunosuppressive therapies even for other than HSCT or HIV.

Evaluation of Th17 immune responses of recombinant DNA vaccine encoding GRA14 and ROP13 genes against Toxoplasma gondii in BALB/c mice

Toxoplasma gondii, a worldwide opportunistic parasite, causes serious diseases in both humans and fetuses with defective immune systems. The development of an effective vaccine is urgently required to prevent and control the spread of toxoplasmosis, caused by the apicomplexan parasite Toxoplasma gondii which is one of the most damaging zoonotic diseases of global importance. Plasmid DNA vaccination is a promising procedure for vaccine development and following the previous studies, pcROP13 + pcGRA14 cocktail DNA vaccine was evaluated for Th17 immune responses. Four groups of BALB/c mice were immunized intramuscularly three times at 2-week intervals. Subsequently, the production of anti- T. gondii antibodies and serum levels of cytokines IL-17, and IL-22 were evaluated against the RH strain of T. gondii. In addition, both the reactive oxygen species (ROS) and parasite load were assessed using ELISA and Q-PCR, respectively. The results of this study showed that high levels of IgG were found in mice immunized with cocktail DNA vaccine (p < 0.05). The cytokines level of Th17, IL-17, and IL-22, increased remarkably in the immunized mice (p < 0.05). Also, significant induction (p < 0.05) was observed in ROS. In addition, immunization with pcROP13 + GRA14 resulted in a considerable decrease in parasite load compared to the control groups (p < 0.05). Based on the results, the pcROP13 + GRA14 cocktail DNA vaccine induced Th17 related cytokines and decreased the parasite load in spleen and brain tissues. Hence, pcGRA14 + pcROP13 cocktails are suitable candidates for DNA-based vaccines and due to the development of protective immune responses against T. gondii infection, future studies may yield promising results using these antigens in vaccine design.

Yeast Shells Encapsulating Adjuvant AS04 as an Antigen Delivery System for a Novel Vaccine against Toxoplasma Gondii

Toxoplasma gondii (T. gondii) infection causes severe zoonotic toxoplasmosis, which threatens the safety of almost one-third of the human population globally. However, there is no effective protective vaccine against human toxoplasmosis. This necessitates anti-T. gondii vaccine development, which is a main priority of public health. In this study, we optimized the adjuvant system 04 (AS04), a vaccine adjuvant constituted by 3-O-desacyl-4'-monophosphoryl lipid A (a TLR4 agonist) and aluminum salts, by packing it within natural extracts of β-glucan particles (GPs) from Saccharomyces cerevisiae to form a GP-AS04 hybrid adjuvant system. Through a simple mixing procedure, we loaded GP-AS04 particles with the total extract (TE) of T. gondii lysate, forming a novel anti-T. gondii vaccine GP-AS04-TE. Results indicated that the hybrid adjuvant can efficiently and stably load antigens, mediate antigen delivery, facilitate the dendritic uptake of antigens, boost dendritic cell maturation and stimulation, and increase the secretion of pro-inflammatory cytokines. In the mouse inoculation model, GP-AS04-TE significantly stimulated the function of dendritic cells, induced a very strong TE-specific humoral and cellular immune response, and finally showed a strong and effective protection against toxoplasma chronic and acute infections. This work proves the potential of GP-AS04 for exploitation as a vaccine against a range of pathogens.

Oxidative Stress as a Possible Target in the Treatment of Toxoplasmosis: Perspectives and Ambiguities

Toxoplasma gondii is an apicomplexan parasite causing toxoplasmosis, a common disease, which is most typically asymptomatic. However, toxoplasmosis can be severe and even fatal in immunocompromised patients and fetuses. Available treatment options are limited, so there is a strong impetus to develop novel therapeutics. This review focuses on the role of oxidative stress in the pathophysiology and treatment of T. gondii infection. Chemical compounds that modify redox status can reduce the parasite viability and thus be potential anti-Toxoplasma drugs. On the other hand, oxidative stress caused by the activation of the inflammatory response may have some deleterious consequences in host cells. In this respect, the potential use of natural antioxidants is worth considering, including melatonin and some vitamins, as possible novel anti-Toxoplasma therapeutics. Results of in vitro and animal studies are promising. However, supplementation with some antioxidants was found to promote the increase in parasitemia, and the disease was then characterized by a milder course. Undoubtedly, research in this area may have a significant impact on the future prospects of toxoplasmosis therapy.

An analytical study on the awareness and practice relating toxoplasmosis among pregnant women in Casablanca, Morocco

BACKGROUND

Although toxoplasmosis is asymptomatic in most cases among pregnant women, it may cause newborn abortions and birth defects if the infection occurs during pregnancy. Therefore, raising awareness and promoting good practices of pregnant women towards toxoplasmosis disease is essential to avoid infection during pregnancy. The aim of this cross-sectional study is to assess toxoplasmosis awareness and its risk-related behavior pregnant women who attended public health centers in one of the biggest Moroccan cities: Casablanca.

METHODS

A structured questionnaire was used to collect data including socio-demographics data, awareness of etiology, modes of transmission and preventive practices towards toxoplasmosis.

RESULTS

This study survey showed that among 390 pregnant women interviewed, 41.2% reported having heard or read information regarding toxoplasmosis. Only 8.1% of them knew that toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, and 13.7% of those who gave a correct answer were aware that the host of toxoplasmosis is cats. There is a significant statistical association between age, level of education and profession of pregnant women and toxoplasmosis awareness. Despite of the majority of the interviewed pregnant women had had effective preventive practices towards toxoplasmosis, 17.4% of pregnant women were convinced that Toxoplasmosis can transmit to the fetus and 14.3% stated it is asymptomatic in most cases.

CONCLUSION

This study highlights the low level of knowledge and awareness of toxoplasmosis among pregnant women in Casablanca/Morocco. Therefore, a special education program targeting all women during their reproductive age is necessary.

Toxoplasma gondii α-amylase deletion mutant is a promising vaccine against acute and chronic toxoplasmosis

Individuals with inhibited immunity may develop lethal toxoplasmosis; thus, a safe and effective vaccine is urged to be developed. Toxoplasma gondii (T. gondii) α-amylase (α-AMY) is one of the enzymes responsible for starch digestion. In the present study, we first generated a ME49Δα-amy mutant and discovered that loss of α-AMY robustly grew in vitro but contributed to significant virulence attenuation in vivo. Therefore, we established a mouse model to explore the protective immunity of Δα-amy mutant against acute and chronic toxoplasmosis. The results indicated that the survival rates of short-term or long-term immunized mice re-infected with the tachyzoites of multiple T. gondii strains were nearly 100%. ME49Δα-amy not only could provide protective immunity against tachyzoites infection but also could resist the infection of tissue cysts. Furthermore, we detected that ME49Δα-amy vaccination could effectively eliminate the proliferation of parasites in mice and prevent the formation of cysts. The significant increases of Th1-type cytokines, Th2-type cytokines and specific total IgG and IgG subclasses (IgG2a and IgG1) confirmed efficiency of a combination of cellular and humoral immunity against infection. In conclusion, ME49Δα-amy attenuated strain can produce strong immune responses to provide efficient protection against toxoplasmosis, which signifies that ME49Δα-amy mutant may be a potential vaccine candidate.

Prevalence of torch infections and its associated poor outcome in high-risk pregnant women of Central India: Time to think for prevention strategies

Introduction

The TORCH infections during pregnancy are associated with adverse congenital abnormalities, poor foetal outcome and subsequent reproductive failures. The absence of baseline data on status of TORCH infections and associated foetal outcomes prompted us to conduct the current study in Central India.

Materials and Methods

: A total of 144 high-risk pregnant women attending tertiary care unit, suspected for TORCH infections were enrolled from August 2017 to December 2018. All the participants were tested for the presence of IgM and IgG antibodies and followed up to record the foetal outcome.

Results

The overall TORCH infection (IgM positivity) positivity rate was 61.1% (88/144). Rubella was the most prevalent infection (46.5%) followed by herpes simplex virus (HSV) 1 and 2 (41%) and cytomegalovirus (CMV) (34.7%). The highest IgG sero-positivity was recorded against CMV (88.6%), followed by Rubella (86.8%), HSV 1 and 2 (28.4%), and toxoplasmosis (15.2%). Follow-up of IgM TORCH positive pregnant women revealed that majority of the neonates/infants are having congenital cardiac abnormalities (39.2%), followed by microcephaly/hydrocephaly (25%), low birth weight (10.7%), and deafness (3.6%). Thirty-two percent of neonatal mortality was associated to multiple TORCH infections.

Conclusion

A high prevalence of IgM seropositivity of TORCH infection was noted in the present study with the increased rate of poor foetal outcome warrants the need of proper prenatal counselling, universal immunisation and nutritional supplements during pregnancy.

[Survey on Toxoplasma gondii infections among three types of populations in Wuxi City]

OBJECTIVE

To investigate the seroprevalence of Toxoplasma gondii infections among patients with rheumatoid arthritis, malignant tumors and schizophrenia in Wuxi City, so as to provide data support for the control of toxoplasmosis in these patients.

METHODS

A total of 205 cases with definitive diagnosis of rheumatoid arthritis, 257 cases with definitive diagnosis of malignant tumors and 235 cases with definitive diagnosis of schizophrenia were recruited, while 250 healthy volunteers served as controls. The demographic features were captured from the study subjects and serum samples were collected. The serum IgG and IgM antibodies against T. gondii were detected using an enzyme-linked immunosorbent assay (ELISA) in all study subjects, and the positive rates of anti-T. gondii IgG and IgM antibodies were compared between the patients and controls.

RESULTS

The seroprevalence of the anti-T. gondii IgG antibody was 20.98%, 24.12% and 24.68% in patients with rheumatoid arthritis, malignant tumors and schizophrenia, which were all significantly greater than in healthy controls (χ² = 31.54, 42.12 and 42.98, all P values < 0.01), and the seroprevalence of the anti - T. gondii IgM antibody was 1.46%, 2.72% and 1.70% among patients with rheumatoid arthritis, malignant tumors and schizophrenia, which were all significantly higher than in healthy controls (χ² = 0.06, 1.52 and 0.21, all P values > 0.05).

CONCLUSIONS

The patients with rheumatoid arthritis, malignant tumors and schizophrenia present with higher seroprevalence of the anti-T. gondii IgG antibody than healthy controls in Wuxi regions. Screening of T. gondii infections among the patients with rheumatoid arthritis, malignant tumors and schizophrenia should be intensified to prevent the damages caused by T. gondii infections.

Knowledge and practices regarding toxoplasmosis in housewives: A cross sectional study in a northern Mexican city

We aimed to determine the knowledge and practices regarding toxoplasmosis among housewives in the northern Mexican city of Durango. One hundred eighty-five women (mean age: 41.27 ± 12.40 years old) with an occupation of housewife were studied. A self-administered questionnaire was used. This tool included items about the parasite Toxoplasma gondii, its transmission routes, general clinical, diagnostic, and treatment aspects of toxoplasmosis, and practices to avoid infection. A minority (<10%) of women knew about the parasite, the disease, how the transmission occurs, the clinical manifestations, how an infection is diagnosed, the treatment, and how to avoid toxoplasmosis. Some women knew that cats can transmit T. gondii infection (20%), and that the parasite can be found in cat feces (20.5%). Only 7.6% of women knew that infection with T. gondii can be transmitted by consumption of contaminated food or water. Only 1.1% of women knew about the prevalence of T. gondii infection. Some (4.9%) women used to taste raw meat while cooking, and 7.6% used to undercook meat. In addition, 20% of women used to eat raw dried meat, and 13.5% consumed untreated water. Less than 90% of women always washed their hands before cooking, and washed fruits or vegetables. The majority (75.1%) of women never wore gloves when handling raw meat. About one quarter (27.6%) of women always froze meat. And 16.2% of women cleaned cat feces. This is the first study regarding knowledge and practices about toxoplasmosis in housewives. Poor knowledge regarding T. gondii infection, toxoplasmosis, and practices to avoid infection among the housewives studied was found. High risk practices for infection were identified. Strategies to improve toxoplasmosis-related knowledge and practices to avoid T. gondii infection and its sequelae in housewives are highly needed.

Virus-like particles containing multiple antigenic proteins of Toxoplasma gondii induce memory T cell and B cell responses

Although the efforts to develop vaccine against Toxoplasma gondii infection were made for decades, there is currently no licensed vaccine available for humans. Upon discovering a number of T or B cell epitope regions from T. gondii IMC, ROP18 and MIC8, multi-antigen VLPs or combination VLPs were generated. Mice immunized with multi-antigen VLPs or combination VLPs were challenge infected with T. gondii (ME49). T. gondii-specific IgG, IgG isotypes and IgA antibody responses, memory T and B cell responses and protection were evaluated. All the mice survived upon T. gondii challenge infection by multi-antigen VLPs vaccination. Vaccinated mice elicited higher levels of parasite-specific IgG and IgG2a antibody responses in sera, IgA antibody responses in feces, CD4+ and CD8+ T cell responses, and cytokines (IFN-γ, IL-10) responses compared to combination VLPs. In particular, the multi-antigen VLPs vaccination showed significantly higher levels of antibody secreting cell (ASC) responses, CD4+ and CD8+ effector memory T cells, and memory B cells than combination VLPs. Multi-antigen VLPs vaccination showed significant reduction of brain cyst counts and size, and all mice survived. Prediction and analysis of epitopes have indicated that IMC, ROP18 and MIC8 showed partially overlapping epitopes for T and B cells. Our results indicated that antibody responses, memory T and B cells induced by multi-antigen VLPs vaccination might contribute to the complete protection upon T. gondii (ME49) challenge infection.

IL-17 and IL-22 elicited by a DNA vaccine encoding ROP13 associated with protection against Toxoplasma gondii in BALB/c mice

Toxoplasma gondii, an intracellular parasitic protozoan, is capable of infecting man and all warm-blooded animals. Cell-mediated immunity is vital in mounting protective responses against T. gondii infection. Recent studies have shown that T-helper (Th) 17 responses may play a key role in parasite control. In this current study, we constructed a DNA vaccine encoding T. gondii ROP13 in a pcDNA vector. Groups of BALB/c mice were immunized intramuscularly with pcROP13 or controls and challenged with the RH strain of T. gondii. The results showed that immunization with pcROP13 could elicit an antibody response against T. gondii. The expression of the canonical Th17 cytokines, interleukin (IL)-17 and IL-22, were significantly increased after immunization with pcROP13 compared with control groups ( p < 0.05). Furthermore, vaccination resulted in a significant decrease in parasite load ( p < 0.05). The induction of Th17 related cytokines, using a ROP13 DNA vaccine, against T. gondii should be considered as a potential vaccine approach for the control of toxoplasmosis.

The One Health Approach to Toxoplasmosis: Epidemiology, Control, and Prevention Strategies

One Health is a collaborative, interdisciplinary effort that seeks optimal health for people, animals, plants, and the environment. Toxoplasmosis, caused by Toxoplasma gondii, is an intracellular protozoan infection distributed worldwide, with a heteroxenous life cycle that practically affects all homeotherms and in which felines act as definitive reservoirs. Herein, we review the natural history of T. gondii, its transmission and impacts in humans, domestic animals, wildlife both terrestrial and aquatic, and ecosystems. The epidemiology, prevention, and control strategies are reviewed, with the objective of facilitating awareness of this disease and promoting transdisciplinary collaborations, integrative research, and capacity building among universities, government agencies, NGOs, policy makers, practicing physicians, veterinarians, and the general public.

A social cost-benefit analysis of two One Health interventions to prevent toxoplasmosis

In the Netherlands, toxoplasmosis ranks second in disease burden among foodborne pathogens with an estimated health loss of 1,900 Disability Adjusted Life Years and a cost-of-illness estimated at €45 million annually. Therefore, effective and preferably cost-effective preventive interventions are warranted. Freezing meat intended for raw or undercooked consumption and improving biosecurity in pig farms are promising interventions to prevent Toxoplasma gondii infections in humans. Putting these interventions into practice would expectedly reduce the number of infections; however, the net benefits for society are unknown. Stakeholders bearing the costs for these interventions will not necessary coincide with the ones having the benefits. We performed a Social Cost-Benefit Analysis to evaluate the net value of two potential interventions for the Dutch society. We assessed the costs and benefits of the two interventions and compared them with the current practice of education, especially during pregnancy. A 'minimum scenario' and a 'maximum scenario' was assumed, using input parameters with least benefits to society and input parameters with most benefits to society, respectively. For both interventions, we performed different scenario analyses. The freezing meat intervention was far more effective than the biosecurity intervention. Despite high freezing costs, freezing two meat products: steak tartare and mutton leg yielded net social benefits in both the minimum and maximum scenario, ranging from €10.6 million to €31 million for steak tartare and €0.6 million to €1.5 million for mutton leg. The biosecurity intervention would result in net costs in all scenarios ranging from €1 million to €2.5 million, due to high intervention costs and limited benefits. From a public health perspective (i.e. reducing the burden of toxoplasmosis) and the societal perspective (i.e. a net benefit for the Dutch society) freezing steak tartare and leg of mutton is to be considered.

A review on inactivation methods of Toxoplasma gondii in foods

Toxoplasmosis is an infection caused by Toxoplasma gondii, a widespread zoonotic protozoan which poses a great threat to human health and economic well-being worldwide. It is usually acquired by ingestion of water contaminated with oocysts from the feces of infected cats or by the ingestion of raw or undercooked foodstuff containing tissue cysts. The oocyst can contaminate irrigation water and fresh edible produce. It is estimated that approximately one-third of the human population worldwide harbor this parasite. Infection with T. gondii is an important cause of diseases of the central nervous system and the eye in immunocompromised and immunocompetent individuals. The purpose of this study was to evaluate the efficacy and applicability of thermal (heating, cooking, freezing and low temperature), non-thermal (high pressure processing, ionizing irradiation and curing) and chemical and biochemical (disinfection, essential oils and biochemical methods such as enzymes, nanoparticles, antibiotics and immune response) treatments for the inactivation, inhabitation or to kill T. gondii in foodstuff intended for public consumption and under experimental conditions.

Evaluation of Protective Immune Response Induced by a DNA Vaccine Encoding GRA8 against Acute Toxoplasmosis in a Murine Model

Toxoplasma gondii is an apicomplexan zoonotic protozoan parasite that infects most species of warm-blooded animals, including humans. The heavy incidence and severe or lethal damage caused by T. gondii infection clearly indicate a need for the development of an effective vaccine. T. gondii GRA8 is a member of the dense granules protein family and is used as a marker of acute infection. In the present study, we evaluated the protective immunity induced by DNA vaccination based on a recombinant eukaryotic plasmid, pDsRed2-GRA8, against acute toxoplasmosis in mice. BALB/c mice were intramuscularly immunized with the pDsRed2-GRA8 plasmid and then challenged by infection with the highly virulent GFP-RH strain of T. gondii. The specific immune responses and protective efficacy against T. gondii of this vaccine were analyzed by measuring cytokine and serum antibody titers, splenocyte proliferation assays, and the survival times of mice after challenge. Our results showed that mice immunized with pDsRed2-GRA8 demonstrated specific humoral and cellular responses, induced higher IgG antibody titers with predominant IgG2a production; increased levels of IL-10, IL-12 (p70), IFN-γ, TNF-α, and splenocyte proliferation; and prolonged survival times compared to those of control mice. The present study showed that DNA immunization with pDsRed2-GRA8 induced humoral and cellular immune responses, and all immunized mice showed greater Th1-type immune responses and longer survival times than those of control mice. These results indicated that T. gondii GRA8 DNA immunization induces a partial protective effect against acute toxoplasmosis.

Risk Assessment of Human Toxoplasmosis Associated with the Consumption of Pork Meat in Italy

Toxoplasmosis is a cosmopolitan disease and has a broad range of hosts, including humans and several wild and domestic animals. The human infection is mostly acquired through the consumption of contaminated food and pork meat has been recognized as one of the major sources of transmission. There are, however, certain fundamental differences between countries; therefore, the present study specifically aims to evaluate the exposure of the Italian population to Toxoplasma gondii through the ingestion of several types of pork meat products habitually consumed in Italy and to estimate the annual number of human infections within two subgroups of the population. A quantitative risk assessment model was built for this reason and was enriched with new elements in comparison to other similar risk assessments in order to enhance its accuracy. Sensitivity analysis and two alternative scenarios were implemented to identify the factors that have the highest impact on risk and to simulate different plausible conditions, respectively. The estimated overall average number of new infections per year among adults is 12,513 and 92 for pregnant women. The baseline model showed that almost all these infections are associated with the consumption of fresh meat cuts and preparations (mean risk of infection varied between 4.5 × 10^-5 and 5.5 × 10^-5 ) and only a small percentage is due to fermented sausages/salami. On the contrary, salt-cured meat products seem to pose minor risk but further investigations are needed to clarify still unclear aspects. Among all the considered variables, cooking temperature and bradyzoites' concentration in muscle impacted most the risk.

[Epidemic situation and control strategy of major food - borne parasitic diseases in Guangxi Zhuang Autonomous Region]

Food-borne parasitic diseases have become a public health problem for social economy and health care. In this paper, the epidemic situation of major food-borne parasitic diseases in Guangxi Zhuang Autonomous Region, such as toxoplasmosis and clonorchiasis, are reviewed, and the countermeasures of prevention and control are put forward.

Parasite Carbohydrate Vaccines

Vaccination is an efficient means of combating infectious disease burden globally. However, routine vaccines for the world's major human parasitic diseases do not yet exist. Vaccines based on carbohydrate antigens are a viable option for parasite vaccine development, given the proven success of carbohydrate vaccines to combat bacterial infections. We will review the key components of carbohydrate vaccines that have remained largely consistent since their inception, and the success of bacterial carbohydrate vaccines. We will then explore the latest developments for both traditional and non-traditional carbohydrate vaccine approaches for three of the world's major protozoan parasitic diseases-malaria, toxoplasmosis, and leishmaniasis. The traditional prophylactic carbohydrate vaccine strategy is being explored for malaria. However, given that parasite disease biology is complex and often arises from host immune responses to parasite antigens, carbohydrate vaccines against deleterious immune responses in host-parasite interactions are also being explored. In particular, the highly abundant glycosylphosphatidylinositol molecules specific for Plasmodium, Toxoplasma, and Leishmania spp. are considered exploitable antigens for this non-traditional vaccine approach. Discussion will revolve around the application of these protozoan carbohydrate antigens for vaccines currently in preclinical development.

Vaccination with Recombinant Microneme Proteins Confers Protection against Experimental Toxoplasmosis in Mice

Toxoplasmosis, a zoonotic disease caused by Toxoplasma gondii, is an important public health problem and veterinary concern. Although there is no vaccine for human toxoplasmosis, many attempts have been made to develop one. Promising vaccine candidates utilize proteins, or their genes, from microneme organelle of T. gondii that are involved in the initial stages of host cell invasion by the parasite. In the present study, we used different recombinant microneme proteins (TgMIC1, TgMIC4, or TgMIC6) or combinations of these proteins (TgMIC1-4 and TgMIC1-4-6) to evaluate the immune response and protection against experimental toxoplasmosis in C57BL/6 mice. Vaccination with recombinant TgMIC1, TgMIC4, or TgMIC6 alone conferred partial protection, as demonstrated by reduced brain cyst burden and mortality rates after challenge. Immunization with TgMIC1-4 or TgMIC1-4-6 vaccines provided the most effective protection, since 70% and 80% of mice, respectively, survived to the acute phase of infection. In addition, these vaccinated mice, in comparison to non-vaccinated ones, showed reduced parasite burden by 59% and 68%, respectively. The protective effect was related to the cellular and humoral immune responses induced by vaccination and included the release of Th1 cytokines IFN-γ and IL-12, antigen-stimulated spleen cell proliferation, and production of antigen-specific serum antibodies. Our results demonstrate that microneme proteins are potential vaccines against T. gondii, since their inoculation prevents or decreases the deleterious effects of the infection.

Phosphatidylthreonine and Lipid-Mediated Control of Parasite Virulence

The major membrane phospholipid classes, described thus far, include phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylserine (PtdSer), and phosphatidylinositol (PtdIns). Here, we demonstrate the natural occurrence and genetic origin of an exclusive and rather abundant lipid, phosphatidylthreonine (PtdThr), in a common eukaryotic model parasite, Toxoplasma gondii. The parasite expresses a novel enzyme PtdThr synthase (TgPTS) to produce this lipid in its endoplasmic reticulum. Genetic disruption of TgPTS abrogates de novo synthesis of PtdThr and impairs the lytic cycle and virulence of T. gondii. The observed phenotype is caused by a reduced gliding motility, which blights the parasite egress and ensuing host cell invasion. Notably, the PTS mutant can prevent acute as well as yet-incurable chronic toxoplasmosis in a mouse model, which endorses its potential clinical utility as a metabolically attenuated vaccine. Together, the work also illustrates the functional speciation of two evolutionarily related membrane phospholipids, i.e., PtdThr and PtdSer.

An exclusive membrane lipid, phosphatidylthreonine, is revealed to be naturally abundant in the widespread protist parasite Toxoplasma gondii, where it has evolved adaptively and is essential for parasite virulence.

Lipids are essential constituents of biological membranes, and most organisms across the tree of life use a relatively limited repertoire of lipids in their membranes. This work reveals the natural and abundant presence of an exclusive lipid phosphatidylthreonine (PtdThr) in Toxoplasma gondii, a ubiquitous protozoan parasite of humans and animals. PtdThr is made by a novel parasite-specific enzyme, PtdThr synthase, which has evolved from the widespread enzyme phosphatidylserine synthase. The study shows that PtdThr is required for asexual reproduction and virulence of the parasite in vivo, and a metabolically attenuated mutant strain of Toxoplasma lacking PtdThr can protect vaccinated mice against acute and currently incurable chronic infection. This discovery demonstrates adaptive “speciation” of PtdThr from an otherwise near-universal membrane lipid phosphatidylserine and reveals de novo PtdThr synthesis in T. gondii as a potential drug target.

[Expression of Cocktail DNA Vaccine Comprising Toxoplasma gondii SAGI, MIC3 and ROP2 Using Fluorescent Protein-Reporting Vectors and Evaluation of Its Immunogenicity]

OBJECTIVE

To construct a cocktail DNA vaccine that expresses multiple genes of Toxoplasma gondii and investigate its immunogenicity in mice.

METHODS

Genes for surface antigens (SAG), microneme(MIC), and rhoptry protein(ROP) were amplified from genomic DNA of T. gondii and then cloned separately into eukaryotic fluorescent protein expression vectors pShuttle-CMV-MCS-EFlα-AmCyan, pLVX-IRES-Zsgreen and pLVX-IRES-rfp, to construct expression plasmids pShuttle-SAG1, pLVX-Zsgreen-MIC3 and pLVX-rfp-ROP2. 293F cells were transfected with a combination of the three plasmids using the polyethylenimine (PEI) method. Forty-eight hours later, the expression of the three genes was observed under a fluorescence microscope. In addition, 30 C57BL/6 mice were randomized to receive intramuscular injection of saline (50 pA, group A), pShuttle+pLVX-Zsgreen+pLVX-rfp empty plasmids(2 μg/μL, 17 μL of each, group B) and pShuttle-SAG1+pLVX-Zsgreen-MIC3+ pLVX-rfp-ROP2 recombinant plasmid (2 μg/μL, 17 μL of each, group C). After 28 days, anti-T. gondii antibody in mouse serum was detected by ELISA, to evaluate the immunogenicity of the vaccine.

RESULTS

The SAG1, MIC3 and ROP2 genes were amplified from the genomic DNA, with product sizes of 1, 1.1 and 1.7 kb. The eukaryotic expression plasmids pShuttle-SAG1, pLVX-Zsgreen-MIC3 and pLVX-rfp-ROP2 were constructed, and the corresponding fluorescences (blue, green and red) were observed after transfection. On day 28 after mouse vaccination, ELISA showed that the mean A(450) values for serum IgG in groups A, B and C were (0.620±0.029), (0.741±0.040) and (1.561±0.131), respectively, with the group C value being significantly higher than the others (P<0.01).

CONCLUSION

The cocktail DNA vaccine comprising T. gondii SAG1, MIC3 and ROP2 shows promising immunogenicity in mice, and the fluorescent protein expression vectors are reliable tools for expression of the target genes.

Atovaquone for Prophylaxis of Toxoplasmosis after Allogeneic Hematopoietic Stem Cell Transplantation

Toxoplasmosis and infections by other opportunistic agents such as Pneumocystis jirovecii constitute life-threatening risks for patients after allogeneic hematopoietic stem cell transplantation. Trimethoprim/sulfamethoxazole (TMP-SMX) has been well established for post-transplant toxoplasmosis and pneumocystis prophylaxis, but treatment may be limited due to toxicity. We explored atovaquone as an alternative and compared it with TMP-SMX regarding toxicity and efficacy during the first 100 days after transplantation in 155 consecutive adult stem cell recipients. Eight patients with a prior history of TMP-SMX intolerance received atovaquone as first-line prophylaxis. TMP-SMX was used for 141 patients as first-line strategy, but 13 patients (9.2%) were later switched to atovaquone due to TMP-SMX toxicity or gastrointestinal symptoms. No active toxoplasmosis or active P. jirovecii infection developed under continued prophylaxis with either TMP-SMX or atovaquone. However, for reasons of TMP-SMX and/or atovaquone toxicity, 7 patients were unable to tolerate any efficacious toxoplasmosis prophylaxis and therefore obtained inhalative pentamidine as P. jirovecii prophylaxis but no toxoplasmosis prophylaxis. Importantly, 2 of these patients developed severe toxoplasmosis. In summary, atovaquone appears as a valid alternative for at least some post-transplant patients who cannot tolerate TMP-SMX. This should be further confirmed by multicenter trials.

[Study and application of surface antigen in tachyzoites of Toxoplasma gondii]

Toxoplasma gondii is an intracellular protozoan parasite that infects all warm-blooded animals. The surface antigens of T. gondii with the potential for application as antigens of diagnosis and vaccines have been studied extensively in recent years, especially for P43, P35, P30, P23 and P22. The studies on the surface antigen in tachyzoites of T. gondii are reviewed in this paper.

Survey of obstetrician-gynecologists in the United States about toxoplasmosis: 2012 update

PURPOSE

Toxoplasmosis, caused by the parasite Toxoplasma gondii, can have serious impacts on fetal development in the setting of acute maternal primary infection. The American College of Obstetricians and Gynecologists (ACOG) sought to determine current knowledge, practices, opinions, and educational preferences regarding T. gondii infection in pregnancy among ACOG members practicing prenatal care.

METHODS

ACOG sent a survey to 1,056 members chosen by stratified random sampling from membership lists, including 370 participants and 686 non-participants in the Collaborative Ambulatory Research Network (CARN). Mailings were sent up to four times to nonresponders.

RESULTS

Survey minimum response rates were 40.3% (CARN) and 19.7% (non-CARN); response rates adjusted for imputed non-eligibility were 59.7% (CARN) and 22.6% (non-CARN). Among providers, 80.2% had diagnosed no acute maternal T. gondii infections in the past 5 years, 12.7% correctly identified the screening role of the Toxoplasma avidity test, 42.6% performed serologic T. gondii screening for at least some asymptomatic pregnant women, and 62.1% of those who so did used appropriate approaches. Providers in the northeastern United States were 2.02 times more likely to routinely screen than those in the west (p = 0.025) and female providers were 1.48 times more likely than male providers (p = 0.047). The potential educational interventions considered useful by the most practitioners were updated ACOG guidelines on screening (81.4%) and management (71.7%) for acute T. gondii infection in pregnancy.

CONCLUSIONS

ACOG members would benefit from educational efforts targeted at risk factor counseling and screening approaches.

What information do Dutch midwives give clients about toxoplasmosis, listeriosis and cytomegalovirus prevention? An exploratory study of videotaped consultations

OBJECTIVE

To assess information provided by midwives about methods to prevent toxoplasmosis, listeriosis and cytomegalovirus, and whether the amount of provided information varied according to clients' and midwives' characteristics.

METHODS

Intake consultations with 229 clients in four midwifery practices were videotaped between August 2010 and April 2011. Videotaped intake consultations, where infectious disease prevention were discussed, were evaluated, using a specifically designed nine-item scoring tool. Midwives and clients filled in a questionnaire about their background characteristics. Multilevel linear regression analysis was performed to establish associations between the amount of information provided and clients' and midwives' characteristics.

RESULTS

In total 172 consultations with fifteen midwives were suitable for analyses. Information about not eating raw or undercooked meat and not consuming unpasteurized dairy products was provided most often. Information about not sharing eating utensils with small children and thoroughly reheating all ready-to-eat foods were rarely provided. More information was provided when the client was a primigravidae or the consultation lasted longer than 50min.

CONCLUSION

Information on infectious disease prevention given to pregnant women by primary care midwives was insufficient; especially for cytomegalovirus prevention.

PRACTICE IMPLICATIONS

A guideline for professionals on preventable infectious diseases may be useful to inform pregnant women properly.

Neglected parasitic infections in the United States: toxoplasmosis

Toxoplasma gondii is a leading cause of severe foodborne illness in the United States. Population-based studies have found T. gondii infection to be more prevalent in racial/ethnic minority and socioeconomically disadvantaged groups. Soil contaminated with cat feces, undercooked meat, and congenital transmission are the principal sources of infection. Toxoplasmosis-associated illnesses include congenital neurologic and ocular disease; acquired illness in immunocompetent persons, most notably ocular disease; and encephalitis or disseminated disease in immunosuppressed persons. The association of T. gondii infection with risk for mental illness is intriguing and requires further research. Reduction of T. gondii in meat, improvements in hygiene and food preparation practices, and reduction of environmental contamination can prevent toxoplasmosis, but more research is needed on how to implement these measures. In addition, screening and treatment may help prevent toxoplasmosis or reduce the severity of disease in some settings.

[Pregnancy and vaccinoprevention]

Vaccinations protect woman and her fetus against different infectious diseases, but their application on pregnant should be extremely responsible. In this review I present information about some infectious diseases and vaccines during pregnancy. Women, planning to get pregnant should be advised to do serological tests in order to find out their immune status against some infections, leading to fetal congenital malformations (rubella, chicken pox, hepatitis B) and if necessary to get vaccinated at least a month before pregnancy. Despite the lack of vaccines against Cytomegalovirus (CMV), parvovirus 19 and Toxoplasma gondii it is good to know woman's immune status against these infections in order to clarify the clinical approach in case of future contact with sick or carriers. Parvovirus 19 could cause fetal death, while CMV could be transmitted to the child. Immune women wouldn't get sick and wouldn't transmit Toxoplasmagondii to the fetus during pregnancy. Recommended vaccines before pregnancy include vaccines against flu, human papilloma virus, MMR (morbilli, measles, rubella), Tdap (tetanus, diphtheria, whooping cough), chicken pox. CDC-Atlanta recommends during pregnancy two vaccines--against flu, in case it wasn't done before pregnancy, and Tdap during every pregnancy between 27-th and 36-th gestation week. Whooping cough is very dangerous for the baby during the first two months after birth, while it is not yet vaccinated. From this point of view it is of best interest of the mother to have strong immunity in order to transfer antibodies during breastfeeding, as well as for the father and the rest who will take care for the newborn child to be vaccinated against whooping cough. During pregnancy vaccinations against tuberculosis, morbilli, measles, rubella, meningococcal disease, typhoid fever and chicken pox are contraindicated. In case of contact vaccinations against rabies, anthrax, small pox, poliomyelitis and yellow fever should be taken into consideration. Immediately after birth, if the vaccination against whooping cough is missed young mother vaccination is recommended. The vaccination is one of the greatest achievements of the modern medicine, but it is still an object of vigorous attacks, concerning used products safety. One of the most spreading fears is about sterility after vaccination. Over a period of three years (2009-2012) 563 women were vaccinated by SACMEH against HPV. Forty two of them (13.40%) interrupt vaccination due to pregnancy (18 of them after the first shot and 24 after the second shot). Our observations show, that this vaccine is carried out good by the patients, tit is safe and does not cause sterility.

Evaluation on the immune response induced by DNA vaccine encoding MIC8 co-immunized with IL-12 genetic adjuvant against Toxoplasma gondii infection

OBJECTIVE

To examine the immunoprotection effect induced by MIC8 DNA vaccine co-immunized with a plasmid encoding murine IL-12 (pcIL-12) as an adjuvant in mice against the challenge of Toxoplasma gondii.

METHODS

The gene sequence encoding MIC8 of T. gondii RH strain was inserted into eukaryotic expression vector pcDNA3.1 to construct the pcMIC8 expression plasmid. The recombinant plasmid was transfected into HeLa cells to test its expression and the recombinant protein was then characterized by Western blotting. Eighty Kunming mice were randomly divided into 5 groups (16 per group): 3 control groups (PBS, pcDNA3.1, and pcIL-12), pcMIC8 group, and pcMIC8 plus pcIL-12 group. Mice in the pcMIC8 plus pcIL-12 group were co-injected intramuscularly at a dosage of 100 microl each of pcMIC8 and pcIL-12 suspended in 100 microg sterile PBS. Mice in other groups were inoculated with PBS, pcDNA3.1, pcIL-12, and pcMIC8 respectively following the same protocol. All the mice received three immunizations at 2-week intervals. Serum samples were collected on day 0, 13, 27, 41, and 55 before each inoculation for determining antibody IgG, IgG subclass IgG2a. Four weeks after the final immunization, IFN-gamma and IL-4 levels in splenocytes cultures from immunized mice were detected by ELISA. The mice were challenged with 10(3) tachyzoites of the virulent T. gondii RH strain three weeks after the last immunization to observe the survival time.

RESULTS

Western blotting showed that the protein extracts in HeLa cells upon transfection with pcMIC8 were effectively expressed in cells. The levels of IgG (0.51 +/- 0.028) and IgG2a (0.261 +/- 0.04)(on day 55) in mice immunized with pcMIC8 plus pcIL-12 were higher than pcMIC8 group (497.65 +/- 98.15) and control groups (PBS 47.18 +/- 2.73, pcDNA3.1 50.08 +/- 4.62, pcIL-12 118.15 +/- 12.73) (P < 0.05). There was no significant difference in the level of IgG 1 and IL-4 among the five groups (P > 0.05). After a lethal challenge of T. gondii RH strain, the survival time in mice immunized with pcMIC8 plus pcIL-12 (15d) was prolonged in comparison to that of pcMIC8 (10d) and control groups (PBS 5 d, pcDNA3.1 6d, pcIL-12 8 d) (P < 0.05).

CONCLUSION

The immune responses induced by the combined use of the recombinant plasmid encoding MIC8 of T. gondii with murine IL-2 gene adjuvant can be enhanced.

Zoonotic infections in Alaska: disease prevalence, potential impact of climate change and recommended actions for earlier disease detection, research, prevention and control

Over the last 60 years, Alaska's mean annual temperature has increased by 1.6°C, more than twice the rate of the rest of the United States. As a result, climate change impacts are more pronounced here than in other regions of the United States. Warmer temperatures may allow some infected host animals to survive winters in larger numbers, increase their population and expand their range of habitation thus increasing the opportunity for transmission of infection to humans. Subsistence hunting and gathering activities may place rural residents of Alaska at a greater risk of acquiring zoonotic infections than urban residents. Known zoonotic diseases that occur in Alaska include brucellosis, toxoplasmosis, trichinellosis, giardiasis/cryptosporidiosis, echinococcosis, rabies and tularemia. Actions for early disease detection, research and prevention and control include: (1) determining baseline levels of infection and disease in both humans and host animals; (2) conducting more research to understand the ecology of infection in the Arctic environment; (3) improving active and passive surveillance systems for infection and disease in humans and animals; (4) improving outreach, education and communication on climate-sensitive infectious diseases at the community, health and animal care provider levels; and (5) improving coordination between public health and animal health agencies, universities and tribal health organisations.

[Survey of Toxoplasma gondii infection among pregnant women in Jiangsu Province, China]

OBJECTIVE

To understand the situation of Toxoplasma gondii infection among pregnant women in Jiangsu Province.

METHODS

The pregnant women from 7 cities in Jiangsu Province were involved in this survey and the information was recorded according to the request of unified admission information of the case questionnaire of toxoplasmosis in Jiangsu Province. The specific antibodies IgM and IgG to Toxoplasma gondii in sera of these pregnant women were tested by ELISA.

RESULTS

The specific antibody IgM to Toxoplasma gondii of all the respondents was negative. The positive rate of IgG was 3.98% (43/1 081), which was little different from the control group's 2.27% (4/176), and every city shared a similar positive rate. The positive rate of IgG of early pregnant women was 3.78%, which was also not obviously different from the 4.17% appearing in mid and late pregnant women. The respondents who previously had pathological abortions did not show positive IgG. Only 1.84% (8/435) of pregnant women had had the examinations related to Toxoplasma gondii before this survey.

CONCLUSIONS

The rate of Toxoplasma gondii infection is low among pregnant women in Jiangsu Province. The situations in different areas are not far from each other. We should enhance the peri-conception tests of Toxoplasma gondii and take prevention and treatment countermeasures based on corresponding objects, and also further strengthen the healthy education.