Congenital toxoplasmosis--prenatal aspects of Toxoplasma gondii infection

Toxoplasma gondii (T. gondii) is the cause of toxoplasmosis. Primary infection in an immunocompetent person is usually asymptomatic. Serological surveys demonstrate that world-wide exposure to T. gondii is high (30% in US and 50–80% in Europe). Vertical transmission from a recently infected pregnant woman to her fetus may lead to congenital toxoplasmosis. The risk of such transmission increases as primary maternal infection occurs later in pregnancy. However, consequences for the fetus are more severe with transmission closer to conception. The timing of maternal primary infection is, therefore, critically linked to the clinical manifestations of the infection. Fetal infection may result in natural abortion. Often, no apparent symptoms are observed at birth and complications develop only later in life. The laboratory methods of assessing fetal risk of T. gondii infection are serology and direct tests.

Screening programs for women at childbearing age or of the newborn, as well as education of the public regarding infection prevention, proved to be cost-effective and reduce the rate of infection.

The impact of antiparasytic therapy on vertical transmission from mother to fetus is still controversial. However, specific therapy is recommended to be initiated as soon as infection is diagnosed.     

Arctigenin exhibits hepatoprotective activity in Toxoplasma gondii-infected host through HMGB1/TLR4/NF-κB pathway

Toxoplasmosis is a parasitic zoonosis with the highest incidence in humans. Severe lesions due to acute toxoplasmosis have been recorded in the visceral organs including the liver, where hepatocytes and Kupffer cells are important innate immune cells. Arctigenin (AG) is a bioactive ingredient of Arctium lappa L. and increasing evidence suggests that AG exhibits anti-oxidant, anti-inflammatory and anti-Toxoplasma gondii (T. gondii) effects. However, the role of AG in acute liver damage induced by T. gondii infection remains unclear. In this study, we analyzed the effects of AG against T. gondii-induced liver damage by establishing an in vitro infection model using a murine liver cell line (NCTC-1469 cells) and an in vivo mouse model with acute T. gondii infection of virulent RH strain. In the current study, AG effectively attenuated hepatocytes apoptosis and inhibited the reproduction of T. gondii. The results of in vitro and in vivo studies showed that AG significantly reduced alanine aminotransferase/aspartate aminotransferase activities and lessened pathological damage of liver. Moreover, AG suppressed T. gondii-induced inducible nitric oxide synthase production. AG also attenuated liver inflammation by inhibiting T. gondii-induced activation of the high-mobility group box1/toll-like receptor 4/nuclear factor-kappa B (HMGB1/TLR4/NF-κB) signaling pathway. These findings demonstrated that AG exhibited prominent hepatoprotective activities in toxoplasmic liver injury with anti-inflammatory effects by inhibiting the HMGB1/TLR4/NF-κB signaling axis. Thus, this study provides the basis for the development of new drugs to treat toxoplasmic hepatitis.     

Toward detection of toxoplasmosis from urine in mice using hydro-gel nanoparticles concentration and parallel reaction monitoring mass spectrometry

Diagnosis of clinical toxoplasmosis remains a challenge, thus limiting the availability of human clinical samples. Though murine models are an approximation of human response, their definitive infection status and tissue availability make them critical to the diagnostic development process. Hydrogel mesh nanoparticles were used to concentrate antigen to detectable levels for mass spectrometry. Seven Toxoplasma gondii isolates were used to develop a panel of potential peptide sequences for detection by parallel reaction monitoring (PRM) mass spectrometry. Nanoparticles were incubated with decreasing concentrations of tachyzoite lysate to explore the limits of detection of PRM. Mice whose toxoplasmosis infection status was confirmed by quantitative real-time PCR had urine tested by PRM after hydrogel mesh concentration for known T. gondii peptides. Peptides from GRA1, GRA12, ROP4, ROP5, SAG1, and SAG2A proteins were detected by PRM after nanoparticle concentration of urine, confirming detection of T. gondii antigen in the urine of an infected mouse.     

In vitro activity of the interaction between taxifolin (dihydroquercetin) and pyrimethamine against Toxoplasma gondii

Toxoplasmosis is one of the most neglected zoonotic foodborne parasitic diseases that cause public health and socioeconomic concern worldwide. The current drugs used for the treatment of toxoplasmosis have been identified to have clinical limitations. Hence, new drugs are urgently needed to eradicate T.gondii infections globally. Here, an in vitro anti‐Toxoplasma gondii activity of taxifolin (dihydroquercetin) and dihydrofolate inhibitor (pyrimethamine) alone and in combination with a fixed concentration of pyrimethamine were investigated against the rapidly proliferating T.gondii RH strain at 48 hr using colorimetric assay. Pyrimethamine showed the highest anti‐T. gondii activity with IC_50P of 0.84 μg/ml (p > .05), respectively. The combination of pyrimethamine with dihydroquercetin gave a significant inhibitory activity against tachyzoites in in vitro with IC_50p of 1.39 μg/ml (p < .05). The IC_50p ranges obtained for the individual and the combination of taxifolin with pyrimethamine inhibition of parasite growth were not cytotoxic to the infected HFF and Hek‐293 cell lines used. These compounds combination should be investigated further using in vivo model of toxoplasmosis.     

SDS-coated atovaquone nanosuspensions show improved therapeutic efficacy against experimental acquired and reactivated toxoplasmosis by improving passage of gastrointestinal and blood–brain barriers

Toxoplasmic encephalitis (TE) is the most common clinical manifestation of reactivated infection with Toxoplasma gondii in immunocompromised patients that is lethal if untreated. The combination of pyrimethamine plus sulfadiazine or clindamycin is the standard therapy for the treatment of TE, but these combinations are associated with hematologic toxicity and/or life-threatening allergic reactions. Therefore, alternative treatment options are needed. Atovaquone is safe and highly effective against T. gondii in vitro, but the oral micronized solution shows poor bioavailability. We synthesized atovaquone nanosuspensions (ANSs) coated with poloxamer 188 (P188) and sodium dodecyl sulfate (SDS) to improve oral bioavailability and passage through the blood–brain barrier (BBB). Coating of ANSs with SDS resulted in enhanced oral bioavailability and enhanced brain uptake of atovaquone compared to Wellvone^® in murine models of acute and reactivated toxoplasmosis as measured by high performance liquid chromatography (HPLC). Parasite loads and inflammatory changes in brains of mice treated with SDS-coated ANS were significantly reduced compared to untreated controls and to Wellvone^®-treated mice. In conclusion, nanosuspensions coated with SDS may ultimately lead to improvements in the treatment of TE and other cerebral diseases.     

Management of hepatitis B during pregnancy

Introduction: Women of childbearing age or who are pregnant and have hepatitis B infection require specialized management both during and after pregnancy. Effective maternal screening along with judicious use of available antivirals and immunoprophylaxis greatly reduces the perinatal transmission of hepatitis B virus (HBV) and dramatically declines the incidence and prevalence of chronic hepatitis B and its sequelae. Areas covered: A systematic literature search was done using Embase, Medline and Cochrane library from January 1990 to July 2015 and appropriate articles selected for this review. This review highlights the timing of therapy, choice of antiviral agent along with passive and active immunoprophylaxis for infants. Issues regarding breastfeeding in HBV-infected women and who are on antiviral therapy are addressed. Expert opinion: All decisions about starting, continuing or stopping antiviral therapy must consider maternal and fetal risks. Antiviral therapy during the third trimester of pregnancy in women with active disease reduces the risk of perinatal transmission. Safety data in pregnancy are mostly available for lamivudine and tenofovir. However, recent studies have also advocated use of telbivudine in such patients. Detailed discussion with the patient regarding the risks and bene?ts of therapy is very important. Prophylaxis remains the best method of prevention of perinatal transmission.     

Arctigenin ameliorates depression-like behaviors in Toxoplasma gondii-infected intermediate hosts via the TLR4/NF-κB and TNFR1/NF-κB signaling pathways

Toxoplasma gondii (T. gondii) is a known neurotropic protozoan that remains in the central nervous system and induces neuropsychiatric diseases in intermediate hosts. Arctigenin (AG) is one of the major bioactive lignans of the fruit Arctium lappa L. and has a broad spectrum of pharmacological activities such as neuroprotective, anti-inflammatory and anti-T. gondii effects. However, the effect of AG against depressive behaviors observed in T. gondii-infected hosts has not yet been clarified. In the present study, we analyzed the effects of AG against T. gondii-induced depressive behaviors in intermediate hosts using a microglia cell line (BV2 cells) and brain tissues of BALB/c mice during the acute phase of infection with the RH strain of T. gondii. AG attenuated microglial activation and neuroinflammation via the Toll-like receptor/nuclear factor-kappa B (NF-κB) and tumor necrosis factor receptor 1/NF-κB signaling pathways, followed by up-regulating the dopamine and 5-hydroxytryptamine levels and inhibiting the depression-like behaviors of hosts. AG also significantly decreased the T. gondii burden in mouse brain tissues. In conclusion, we elucidated the effects and underlying molecular mechanisms of AG against depressive behaviors induced by T. gondii infection.     

Screening for small molecule inhibitors of Toxoplasma gondii

Introduction: Toxoplasma gondii, the agent that causes toxoplasmosis, is an opportunistic parasite that infects many mammalian species. It is an obligate intracellular parasite that causes severe congenital neurological and ocular disease mostly in immunocompromised humans. The current regimen of therapy includes only a few medications that often lead to hypersensitivity and toxicity. In addition, there are no vaccines available to prevent the transmission of this agent. Therefore, safer and more effective medicines to treat toxoplasmosis are urgently needed.

Areas covered: The author presents in silico and in vitro strategies that are currently used to screen for novel targets and unique chemotypes against T. gondii. Furthermore, this review highlights the screening technologies and characterization of some novel targets and new chemical entities that could be developed into highly efficacious treatments for toxoplasmosis.

Expert opinion: A number of diverse methods are being used to design inhibitors against T. gondii. These include ligand-based methods, in which drugs that have been shown to be efficacious against other Apicomplexa parasites can be repurposed to identify lead molecules against T. gondii. In addition, structure-based methods use currently available repertoire of structural information in various databases to rationally design small-molecule inhibitors of T. gondii. Whereas the screening methods have their advantages and limitations, a combination of methods is ideally suited to design small-molecule inhibitors of complex parasites such as T. gondii.     

Evaluating anti-Toxoplasma gondii activity of new serie of phenylsemicarbazone and phenylthiosemicarbazones in vitro

While Toxoplasma gondii is able to infect and replicate within all eukaryotic cells, tachyzoites are the infective form of T. gondii that invades all eukaryotic cells leading to tissue rupture, the main features of toxoplasmosis. The present study evaluates the activity of (benzaldehyde)-4-phenyl-3-thiosemicarbazone and (benzaldehyde)-(4 or 1)-phenylsemicarbazone against intracellular T. gondii. The nine new compounds were incubated in infected Vero cells at concentrations of 0.01, 0.1, 0.5, and 1.0 mM and evaluated for three main effects: cytotoxicity, infection, and number of intracellular parasites. The cytotoxicity test showed a pattern by analyzing the substituent arylhydrazone, where trihydroxy Compounds 4–9 were cytotoxic at concentrations of 0.5 and 1.0 mM. The results highlight Compound 8, which reduced the number of intracellular parasites by 82 % in a concentration of 0.01 mM and showed a LD50 of 0.3 mM in cell culture. These different biological actions are due to changes in the molecular structure and type of radical present in each compound. All compounds tested were more efficient than the control drug sulfadizine.     

An investigation into the incidence of toxoplasmosis in pregnancy in New Zealand

AIM: To estimate the incidence of toxoplasmosis in pregnancy in New Zealand and consider whether there is a case for screening women in pregnancy. METHODS: The risk of maternal and fetal infection with toxoplasmosis was derived by first determining the rate of maternal seroconversion based on seroprevalence studies. The age-specific number of seroconversions in pregnancy was then estimated from the birth rate. Using reported fetal infection rates after primary maternal infection, the expected number of congenitally infected infants in one year was estimated. These incidences were compared with the number of recognised cases of toxoplasmosis infection in pregnancy and the actual number of positive IgM results at the Wellington Hospital laboratory. Using national births data, this incidence was extrapolated to estimate the number of expected cases in New Zealand. RESULTS: The annual seroconversion rate was 0.62% (95% confidence interval 0.39-0.86). On this basis, 164 primary maternal infections are expected annually with 66 fetuses being infected. Ten patients tested positive for IgM in Wellington, which averaged only one case per year being identified over the time examined in this study. CONCLUSIONS: Very few of the expected cases in pregnancy are diagnosed. Reporting rates were low when toxoplasmosis was a notifiable disease. Other means of improving detection, reporting and the avoidance of infection are discussed. More information is required before screening can be recommended in New Zealand.     

Vaccination in pregnancy

The recent H1N1 influenza pandemic has highlighted the potential for viral infections to cause severe disease in mothers disproportionate to the general population and have deleterious effects on the fetus. Vaccines have been used in pregnant women for over 200 years. Current guidelines recommend vaccination with only inactivated virus due to potential risk to mother and fetus with live vaccine. The exception is during times of pandemic or biological weapons attack, when the risk of life-threatening disease outweighs the risk of vaccination. A paucity of data is available regarding actual risk and mechanisms of live viral vaccine transfer from mother to fetus. Pregnancy-induced changes to the maternal immune system, effects of maternal infection on neonatal immunity, and the role of the placenta in transmission of infection and passive immunity to the fetus are incompletely understood. The aim of this paper is to review available data pertaining to newer vaccines such as the pandemic H1N1 and HPV vaccines in pregnancy, the role of Fc receptors in active transport of immunoglobulin across the placenta, and cytokine activity during maternal infection and after vaccination. We will also discuss potential areas for future research.     

Options for the pharmacotherapy of toxoplasmosis during pregnancy

Toxoplasmosis infection during pregnancy can cause stillbirths, severe mental retardations or ocular disorders that can also occur later in life and have a potential to relapse. As the disease is generally asymptomatic, diagnosis relies on serological tests. Primary prevention intends to prevent the infection of the fetus, while secondary prevention aims at reducing the severity of sequelae. Preventive attitudes regarding congenital toxoplasmosis differ according to countries. In Austria and France, a nationwide programme based on the screening of seronegative pregnant women and the treatment of all seroconversions has been implemented. The UK and Norway have rejected such a screening due to the lack of evidence of its efficacy. A review of published studies showed that no randomised controlled trials have been conducted. The only available data come from retrospective studies and are methodologically flawed. The impact of chemotherapy on primary and secondary prevention still needs to be assessed. This lack of evidence results in conflicting attitudes that increase the anxiety already raised in pregnant women and doctors by the occurrence of a maternal toxoplasmosis during pregnancy. Before making any change in preventative strategy, it is of utmost importance to increase our knowledge on treatment efficacy through proper randomised trials of existing drugs and of new potentially active compounds.     

Options for the pharmacotherapy of toxoplasmosis during pregnancy

Toxoplasmosis infection during pregnancy can cause stillbirths, severe mental retardations or ocular disorders that can also occur later in life and have a potential to relapse. As the disease is generally asymptomatic, diagnosis relies on serological tests. Primary prevention intends to prevent the infection of the fetus, while secondary prevention aims at reducing the severity of sequelae. Preventive attitudes regarding congenital toxoplasmosis differ according to countries. In Austria and France, a nationwide programme based on the screening of seronegative pregnant women and the treatment of all seroconversions has been implemented. The UK and Norway have rejected such a screening due to the lack of evidence of its efficacy. A review of published studies showed that no randomised controlled trials have been conducted. The only available data come from retrospective studies and are methodologically flawed. The impact of chemotherapy on primary and secondary prevention still needs to be assessed. This lack of evidence results in conflicting attitudes that increase the anxiety already raised in pregnant women and doctors by the occurrence of a maternal toxoplasmosis during pregnancy. Before making any change in preventative strategy, it is of utmost importance to increase our knowledge on treatment efficacy through proper randomised trials of existing drugs and of new potentially active compounds.     

7-Deaza-6-benzylthioinosine analogues as subversive substrate of Toxoplasma gondii adenosine kinase: activities and selective toxicities

Toxoplasma gondii adenosine kinase (EC.2.7.1.20) is the major route of adenosine metabolism in this parasite. The enzyme is significantly more active than any other enzyme of the purine salvage in T. gondii and has been established as a potential chemotherapeutic target for the treatment of toxoplasmosis. Certain 6-benzylthioinosines act as subversive substrates of T. gondii, but not human, adenosine kinase. Therefore, these compounds are preferentially metabolized to their respective nucleotides and become selectively toxic against the parasites but not their host. Moreover, 7-deazaadenosine (tubercidin) was shown to be an excellent ligand of T. gondii adenosine kinase. Therefore, we synthesized 7-deaza-6-benzylthioinosine, and analogues with various substitutions at their phenyl ring, to increase the binding affinity of the 6-benzylthioinosines to T. gondii adenosine kinase. Indeed, the 7-deaza-6-benzylthioinosine analogues were better ligands of T. gondii adenosine kinase than the parent compounds, 6-benzylthioinosine and 7-deazainosine. Herein, we report the testing of the metabolism of these newly synthesized 7-deaza-6-benzylthioinosines, as well as their efficacy as anti-toxoplasmic agents in cell culture. All the 7-deaza-6-benzylthioinosine analogues were metabolized to their 5′-monophosphate derivatives, albeit to different degrees. These results indicate that these compounds are not only ligands but also substrates of T. gondii adenosine kinase. All the 7-deaza-6-benzylthioinosine analogues showed a selective antitoxoplasmic effect against wild type parasites, but not mutants lacking adenosine kinase. The efficacy of these compounds varied with the position and nature of the substitution on their phenyl ring. Moreover, none of these analogues exhibited host toxicity. The best compounds were 7-deaza-6-(p-methoxybenzylthio)inosine (IC₅₀ = 4.6 μM), 7-deaza-6-(p-methoxycarbonylbenzylthio)inosine (IC₅₀ = 5.0 μM), and 7-deaza-6-(p-cyanobenzylthio)inosine (IC₅₀ = 5.3 μM). These results further confirm that T. gondii adenosine kinase is an excellent target for chemotherapy and that 7-deaza-6-benzylthioinosines are potential antitoxoplasmic agents.     

Apoptotic activity and anti-Toxoplasma effects of artemether on the tachyzoites and experimental infected Vero and J774 cell lines by Toxoplasma gondii

Objectives:

Drugs used for toxoplasmosis have limited efficacy and also severe side effects. A new drug with good efficacy and limited side effects is need of the hour. We studied the effects of artemether on Toxoplasma gondii in vitro conditions.

Materials and Methods:

Artemether (methyl-ether-qinghaosu) was tested for tachyzoites, J774, and Vero cell lines infected by T. gondii. For evaluating the effect of drugs on Vero cells infected with T. gondii, we designed two separate experiments; in the first experiment, the Vero cells were infected with tachyzoites and then treated with artemether; while in the second one, the tachyzoites were exposed to artemether and then Vero cells were infected with treated tachyzoites. For evaluating the apoptotic effect of artemether on tachyzoites and infected J774 macrophages cell line with T. gondii, we used flow cytometry method. Inhibitory concentration (IC₅₀) was evaluated by intracellular replication of tachyzoites in Vero cells.

Results:

IC₅₀ for infected Vero cells with tachyzoites was determined as 49.13 μg/ml. In pretreated tachyzoites with artemether before entering into Vero cells, IC₅₀ was calculated as 13.15 μg/ml. In both experiments, artemether showed a higher inhibitory effect than sulfadiazine (positive control). Artemether even at the highest concentrations only showed low cytotoxicity on Vero and J774 cell lines. Apoptosis in tachyzoites rise with an increasing concentration of artemether.

Conclusions:

Our findings indicate that artemether is effective to control the tachyzoites of T. gondii in vitro and maybe a good alternative drug for toxoplasmosis.KEY WORDS: Apoptosis, artemether, in vitro, J774, Toxoplasma gondii, Vero     

Prevalence and genotyping of Toxoplasma gondii among Saudi pregnant women in Saudi Arabia

Introduction: Toxoplasma gondii (T. gondii) is an intracellular protozoan that can infect all mammals, who serve as intermediate host. It causes congenital, neurological, eyes complications and mild or asymptomatic infections in humans. Purpose of this study: To investigate not only the prevalence of T. gondii, but also to find out its genotyping using multiple sequential molecular methods to predict exactly the precise genotyping of T. gondii among Saudi pregnant women. Methods: A cross-sectional study was conducted using multi-stage methods. Initial stage involved enrolment of 250 Saudi pregnant women from multi-centre healthcare and community based settings in the capital of Saudi Arabia Riyadh. The second stage was embracement of the laboratory investigation that included Enzyme immunoassay (ELISA), DNA extraction, PCR, nested-PCR assay, and genotyping of the seropositive cases. Results: 203 women agreed to take part in our study with a response rate of 81.2% (203/250). Using ELISA, we found that the prevalence of Toxoplasma gondii IgG and IgM antibodies was 32.5% and 6.4%, respectively. We found that 29 samples (80.6%) were of genotype II; however 7 samples (19.4%) were of genotype III. Conclusion: Defining the population structure of T. gondii from Saudi Arabia has important implications for transmission, immunogenicity, pathogenesis, and in planning preventive strategies. Relationship between such variation in structure and disease manifestation in pregnant women is still difficult to assess due to the role of host immune status and genetic background on the control of infection, and of other parasitic features such as the infecting dose or parasite stage. Our finding of the genotyping of T. gondii might facilitate and inform future studies on comparative genomics and identification of genes that control important biological phenotypes including pathogenesis and transmission among Saudi women.     

Investigation and management of Toxoplasma gondii infection in pregnancy and infancy: a prospective study

Aim:

Toxoplasma gondii infection during pregnancy poses a serious risk to the fetus, therefore timely and accurate diagnosis is essential. The aim of this study was to estimate the frequency of congenital infection via evaluating mother''s immunological status and the possibility to improving the diagnostic and therapeutic approaches.

Methods:

Eighty five mothers with Toxoplasma seroconversion and their offspring were enrolled (among them, 2 spontaneous abortions were documented in the first trimester). Prenatal PCR diagnosis was carried out on 50 patients (60%), with 7 positive cases (14%). Morphological ultrasound scanning revealed anomalies in one fetus. Long-term follow-up included general physical examinations, serological status tested using Western blot, neuro-radiological, ophthalmologic and neurologic examinations, psychological and developmental tests, visual evoked potential tests and audiology tests, as well as anti-Toxoplasma treatment regimes.

Results:

Fourteen (17%) of the infants were infected at one-year serological follow-up. Chi-square for linear trend of vertical transmission from the first to the third trimester was significant (P=0.009). Western blot analysis showed IgM and IgA in half of the infected infants. In 69 uninfected infants, anti-Toxoplasma IgG immunoblot analysis excluded infection within the 3 months in 18 infants (26%) and in the others within 6 months of life. The most relevant instrumental findings are described.

Conclusion:

Western blot analysis may help to evaluate infection within the 6 months of life. The accuracy of ultrasound imaging to determine the brain damage in the fetus and newborns is doubtful, and should be combined with MR imaging. Multistep approaches can improve the timing of postnatal follow-up.     

胎盘早剥的危险因素及妊娠结局分析

目的 研究胎盘早剥的危险因素及妊娠结局.方法 将2012年3月至2015年3月安徽省立医院确诊为胎盘早剥的72例产妇作为研究组,随机选取同期我院分娩的80例产妇为对照组.回顾分析两组产妇年龄、剖宫产史、子痫前期、经产妇、胎膜早破、流产史、男胎等因素与胎盘早剥发生的相关性及妊娠结局.结果 研究组有剖宫产史产妇14例、子痫前期25例、经产妇33例,与对照组比较,差异有统计学意义(P<0.05).研究组死产及新生儿死亡20例、胎儿急性缺氧29例和早产低体质量儿43例,与对照组比较,差异有统计学意义(P<0.05).结论 既往剖宫产史、子痫前期及经产妇是胎盘早剥发生的危险因素;胎盘早剥产妇出现死产及新生儿死亡、胎儿急性缺氧和早产低体质量儿的比例较高.临床应重视胎盘早剥的各种高危因素,早发现、早诊断、早治疗及治疗个体化,改善母婴结局.     

A pilot study on screening for gestational/congenital toxoplasmosis of pregnant women at delivery in the Eastern Province of Saudi Arabia

BackgroundGlobally, congenital toxoplasmosis remains a significant cause of morbidity and mortality, and outbreaks of T. gondii infection represent a major public health threat, especially in developing countries. Evidence in the literature indicates that only a few studies have been conducted on the incidence of maternal and congenital toxoplasmosis in Saudi Arabia. This prospective study aims to measure the overall incidence of congenital toxoplasmosis, both patent and ‘silent’ infection, among pregnant women in the Eastern Province of Saudi Arabia. The study would attempt to relate the cord blood results with the time of seroconversion in the mother, underlining the importance of early intervention in such cases.MethodsFive hundred paired maternal/cord blood samples were tested for anti-Toxoplasma IgG or IgM antibodies. Samples were collected during delivery from mother and newborn (cord blood) from November 2011 to May 2012. Only positive for anti-Toxoplasma IgG or/and IgM cord blood was processed for real-time PCR for confirmation. The age of mothers ranged from 16 to 45 years.ResultsThe sample subjects were tested during child delivery for specific IgG and IgM antibodies against Toxoplasmosis, of which 21.0% (n = 105) mother/baby pairs were found serologically positive for anti-Toxoplasma IgG antibodies. The rate of maternal seropositivity for anti-Toxoplasma IgM antibodies was found among 4 participants (0.8%), who were also seropositive for anti-Toxoplasma IgG antibodies. None of the children tested positive for anti-Toxoplasma IgM antibodies, even those born to mothers with IgM positive. All 105 cord blood tests in the study sample were confirmed negative by real-time PCR. The seroprevalence of Toxoplasma IgG antibodies increased with maternal age, parity, and was significantly higher in women who gave birth to children with congenital anomalies (p = 0.008).ConclusionThe findings of the current study indicate a dire need to develop and implement preventive programs against Toxoplasma gondii infection, as well as a health education program on how to avoid toxoplasmosis for all seronegative women during pregnancy.     

Carbocyclic 6-benzylthioinosine analogues as subversive substrates of Toxoplasma gondii adenosine kinase: Biological activities and selective toxicities

Toxoplasma gondii adenosine kinase (EC 2.7.1.20) is the major route of adenosine metabolism in this parasite. The enzyme is significantly more active than any other enzyme of the purine salvage in T. gondii and has been established as a potential chemotherapeutic target for the treatment of toxoplasmosis. Several 6-benzylthioinosines have already been identified as subversive substrates of the T. gondii but not human adenosine kinase. Therefore, these compounds are preferentially metabolized to their respective nucleotides and become selectively toxic against the parasites but not its host. In the present study, we report the testing of the metabolism of several carbocyclic 6-benzylthioinosines, as well as their efficacy as anti-toxoplasmic agents in cell culture. All the carbocyclic 6-benzylthioinosine analogues were metabolized to their 5′-monophosphate derivatives, albeit to different degrees. These results indicate that these compounds are not only ligands but also substrates of T. gondii adenosine kinase. All the carbocyclic 6-benzylthioinosine analogues showed a selective anti-toxoplasmic effect against wild type parasites, but not mutants lacking adenosine kinase. These results indicate that the oxygen atom of the sugar is not critical for substrate binding. The efficacy of these compounds varied with the position and nature of the substitution on their phenyl ring. Moreover, none of these analogues exhibited host toxicity. The best compounds were carbocyclic 6-(p-methylbenzylthio)inosine (IC₅₀ = 11.9 μM), carbocyclic 6-(p-methoxybenzylthio)inosine (IC₅₀ = 12.1 μM), and carbocyclic 6-(p-methoxycarbonylbenzylthio)inosine (IC₅₀ = 12.8 μM). These compounds have about a 1.5-fold better efficacy relative to their corresponding 6-benzylthioinosine analogues (Rais et al., Biochem Pharmacol 2005;69:1409-19 [29]). The results further confirm that T. gondii adenosine kinase is an excellent target for chemotherapy and that carbocyclic 6-benzylthioinosines are potential anti-toxoplasmic agents.