Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection.

Toxoplasma gondii is an intracellular parasite with a worldwide distribution. Toxoplasma gondii infections are of great concern for public health, and their impact is usually most severe in pregnant women and their foetuses, and in immunocompromised individuals. Displaying considerable genetic diversity, T. gondii strains differ widely according to geographical location, with archetypal strains predominantly found in the Northern Hemisphere and non-archetypal (atypical) strains, with highly diverse genotypes, found mainly in South America. In this review, we present an overview of the identification and distribution of non-archetypal strains of T. gondii. Special attention is paid to the strains that have been isolated in Brazil, their interaction with the host immunological response, and their impact on disease outcomes. The genetic differences among the strains are pivotal to the distinct immunological responses that they elicit. These differences arise from polymorphisms of key proteins released by the parasite, which represent important virulence factors. Infection with divergent non-archetypal strains can lead to unusual manifestations of the disease, even in immunocompetent individuals.

Chronic infection by atypical Toxoplasma gondii strain induces disturbance in microglia population and altered behaviour in mice.

Toxoplasma gondii chronic infection is characterized by the establishment of tissue cysts in the brain and increased levels of IFN-γ, which can lead to brain circuitry interference and consequently abnormal behaviour in mice. In this sense, the study presented here sought to investigate the impact of chronic infection by two T. gondii strains in the brain of infection-resistant mice, as a model for studying the involvement of chronic neuroinflammation with the development of behavioural alterations. For that, male BALB/c mice were divided into three groups: non-infected (Ni), infected with T. gondii ME49 clonal strain (ME49), and infected with TgCkBrRN2 atypical strain (CK2). Mice were monitored for 60 days to establish the chronic infection and then submitted to behavioural assessment. The enzyme-linked immunosorbent assay was used for measurement of specific IgG in the blood and levels of inflammatory cytokines and neurotrophic factors in the brain, and the cell's immunophenotype was determined by multiparametric flow cytometry. Mice infected with ME49 clonal strain displayed hyperlocomotor activity and memory deficit, although no signs of depressive- and/or anxiety-like behaviour were detected; on the other hand, chronic infection with CK2 atypical strain induced anxiety- and depressive-like behaviour. During chronic infection by CK2 atypical strain, mice displayed a higher number of T. gondii brain tissue cysts and inflammatory infiltrate, composed mainly of CD3+ T lymphocytes and Ly6Chi inflammatory monocytes, compared to mice infected with the ME49 clonal strain. Infected mice presented a marked decrease of microglia population compared to non-infected group. Chronic infection with CK2 strain produced elevated levels of IFN-γ and TNF-ɑ in the brain, decreased NGF levels in the prefrontal cortex and striatum, and altered levels of fractalkine (CX3CL1) in the prefrontal cortex and hippocampus. The persistent inflammation and the disturbance in the cerebral homeostasis may contribute to altered behaviour in mice, as the levels of IFN-γ were shown to be correlated with the behavioural parameters assessed here. Considering the high incidence and life-long persistence of T. gondii infection, this approach can be considered a suitable model for studying the impact of chronic infections in the brain and how it impacts in behavioural responses.

Biological activity of 1,2,3-triazole-2-amino-1,4-naphthoquinone derivatives and their evaluation as therapeutic strategy for malaria control.

Malaria can be caused by several Plasmodium species and the development of an effective vaccine is challenging. Currently, the most effective tool to control the disease is the administration of specific chemotherapy; however, resistance to the frontline antimalarials is one of the major problems in malaria control and thus the development of new drugs becomes urgent. The study presented here sought to evaluate the antimalarial activities of compounds derived from 2-amino-1,4-naphthoquinones containing 1,2,3-triazole using in vivo and in vitro models. 1H-1,2,3-Triazole 2-amino-1,4-naphthoquinone derivatives were synthesized and evaluated for antimalarial activity in vitro, using P. falciparum W2 chloroquine (CQ) resistant strain and in vivo using the murine-P. berghei ANKA strain. Acute toxicity was determined as established by the OECD (2001). Cytotoxicity was evaluated against HepG2 and Vero mammalian cell lines. Transmission electron microscopy of the Plasmodium falciparum trophozoite (early and late stages) was used to evaluate the action of compounds derived at ultra-structural level. The compounds displayed low cytotoxicity CC50 > 100 µM, neither did they cause hemolysis at the tested doses and nor the signs of toxicity in the in vivo acute toxicity test. Among the five compounds tested, one showed IC50 values in submicromolar range of 0.8 µM. Compounds 7, 8 and 11 showed IC50 values < 5 µM, and selectivity index (SI) ranging from 6.8 to 343 for HepG2, and from 13.7 to 494.8 for Vero cells. Compounds 8 and 11 were partially active against P. berghei induced parasitemia in vivo. Analysis of the ultrastructural changes associated with the treatment of these two compounds, showed trophozoites with completely degraded cytoplasm, loss of membrane integrity, organelles in the decomposition stage and possible food vacuole deterioration. Our results indicated that compounds 8 and 11 may be considered hit molecules for antimalarial drug discovery platform and deserve further optimization studies.

The imbalance in the relationship between inflammatory and regulatory cytokines during gestational toxoplasmosis can be harmful to fetuses: A systematic review.

Objective: To evaluate the available information on inflammatory and regulatory plasma mediators in pregnant women (PW) diagnosed with toxoplasmosis. Source: The PubMed, Embase, Scopus, and Lilacs databases were evaluated until October 2022. Study eligibility criteria: This review was carried out following the PRISMA and registered on the PROSPERO platform (CRD42020203951). Studies that reported inflammatory mediators in PW with toxoplasmosis were considered. Evaluation methods: After excluding duplicate articles, two authors independently carried out the process of title and abstract exclusion, and a third resolved disagreements when necessary. The full text was evaluated to detect related articles. The extraction table was built from the following data: Author, year of publication, journal name and impact factors, country, study design, number of gestations and maternal age (years), gestational period, diagnosis of toxoplasmosis, levels of inflammatory markers, laboratory tests, and clinical significance. Methodological quality was assessed using Joanna Briggs Institute tools. Results: Of the 1,024 studies reported, only eight were included. Of the 868 PW included in this review, 20.2% were IgM+/IgG- and 50.8% were IgM-/IgG+ to T. gondii, and 29.0% uninfected. Infected PW presented higher plasma levels ofIL-5, IL-6, IL-8, IL-17, CCL5, and IL-10. Regarding the methodological quality, four studies obtained high quality. Data from this review pointed out the maintenance of the inflammatory pattern during pregnancy with a closely related to the parasite. Conclusion: Immune status in PW defined the course of the T. gondii infection, where the equilibrium between inflammatory and regulatory cytokines mitigated the harmful placenta and fetus effects. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD420203951.

Blood-stage antiplasmodial activity and oocyst formation-blockage of metallo copper-cinchonine complex.

In the fight against malaria, the key is early treatment with antimalarial chemotherapy, such as artemisinin-based combination treatments (ACTs). However, Plasmodium has acquired multidrug resistance, including the emergence of P. falciparum strains with resistance to ACT. The development of novel antimalarial molecules, that are capable of interfering in the asexual and sexual blood stages, is important to slow down the transmission in endemic areas. In this work, we studied the ability of the mettalo copper-cinchonine complex to interfere in the sexual and asexual stages of Plasmodium. The tested compound in the in vitro assay was a cinchonine derivative, named CinCu (Bis[Cinchoninium Tetrachlorocuprate(II)]trihydrate). Its biological functions were assessed by antiplasmodial activity in vitro against chloroquine-resistant P. falciparum W2 strain. The mice model of P. berghei ANKA infection was used to analyze the antimalarial activity of CinCu and chloroquine and their acute toxicity. The oocyst formation-blocking assay was performed by experimental infection of Anopheles aquasalis with P. vivax infected blood, which was treated with different concentrations of CinCu, cinchonine, and primaquine. We found that CinCu was able to suppress as high as 81.58% of parasitemia in vitro, being considered a molecule with high antiplasmodial activity and low toxicity. The in vivo analysis showed that CinCu suppressed parasitemia at 34% up to 87.19%, being a partially active molecule against the blood-stage forms of P. berghei ANKA, without inducing severe clinical signs in the treated groups. The transmission-blocking assay revealed that both cinchonine and primaquine were able to reduce the infection intensity of P. vivax in A. aquasalis, leading to a decrease in the number of oocysts recovered from the mosquitoes' midgut. Regarding the effect of CinCu, the copper-complex was not able to induce inhibition of P. vivax infection; however, it was able to induce an important reduction in the intensity of oocyst formation by about 2.4 times. It is plausible that the metallo-compound also be able to interfere with the differentiation of parasite stages and/or ookinete-secreted chitinase into the peritrophic matrix of mosquitoes, promoting a reduction in the number of oocysts formed. Taken together, the results suggest that this compound is promising as a prototype for the development of new antimalarial drugs. Furthermore, our study can draw a new pathway for repositioning already-known antimalarial drugs by editing their chemical structure to improve the antimalarial activity against the asexual and sexual stages of the parasite.

Chronic Toxoplasma gondii infection contributes to perineuronal nets impairment in the primary somatosensory cortex.

Toxoplasma gondii is able to manipulate the host immune system to establish a persistent and efficient infection, contributing to the development of brain abnormalities with behavioral repercussions. In this context, this work aimed to evaluate the effects of T. gondii infection on the systemic inflammatory response and structure of the primary somatosensory cortex (PSC). C57BL/6 and BALB/c mice were infected with T. gondii ME49 strain tissue cysts and accompanied for 30 days. After this period, levels of cytokines IFN-γ, IL-12, TNF-α and TGF-ß were measured. After blood collection, mice were perfused and the brains were submitted to immunohistochemistry for perineuronal net (PNN) evaluation and cyst quantification. The results showed that C57BL/6 mice presented higher levels of TNF-α and IL-12, while the levels of TGF-ß were similar between the two mouse lineages, associated with the elevated number of tissue cysts, with a higher occurrence of cysts in the posterior area of the PSC when compared to BALB/c mice, which presented a more homogeneous cyst distribution. Immunohistochemistry analysis revealed a greater loss of PNN labeling in C57BL/6 animals compared to BALB/c. These data raised a discussion about the ability of T. gondii to stimulate a systemic inflammatory response capable of indirectly interfering in the brain structure and function.

Toxoplasma gondii infection damages the perineuronal nets in a murine model.

BACKGROUND: Behavioral and neurochemical alterations associated with toxoplasmosis may be influenced by the persistence of tissue cysts and activation of an immune response in the brain of Toxoplasma gondii-infected hosts. The cerebral extracellular matrix is organised as perineuronal nets (PNNs) that are both released and ensheath by some neurons and glial cells. There is evidences to suggest that PNNs impairment is a pathophysiological mechanism associated with neuropsychiatric conditions. However, there is a lack of information regarding the impact of parasitic infections on the PNNs integrity and how this could affect the host's behavior. OBJECTIVES: In this context, we aimed to analyse the impact of T. gondii infection on cyst burden, PNNs integrity, and possible effects in the locomotor activity of chronically infected mice. METHODS: We infected mice with T. gondii ME-49 strain. After thirty days, we assessed locomotor performance of animals using the open field test, followed by evaluation of cysts burden and PNNs integrity in four brain regions (primary and secondary motor cortices, prefrontal and somesthetic cortex) to assess the PNNs integrity using Wisteria floribunda agglutinin (WFA) labeling by immunohistochemical analyses. FINDINGS AND MAIN CONCLUSIONS: Our findings revealed a random distribution of cysts in the brain, the disruption of PNNs surrounding neurons in four areas of the cerebral cortex and hyperlocomotor behavior in T. gondii-infected mice. These results can contribute to elucidate the link toxoplasmosis with the establishment of neuroinflammatory response in neuropsychiatric disorders and to raise a discussion about the mechanisms related to changes in brain connectivity, with possible behavioral repercussions during chronic T. gondii infection.

Genetic polymorphism in IL17RA induces susceptibility to Toxoplasma gondii infection in Brazilian pregnant women.

Congenital toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, an obligate intracellular parasite which can cause fetal death/abortion and can induce damage in the brain and eyes of the infected babies. The environmental and genetic factors associated with T. gondii and the maternal immune response, drive part of the pathogenesis of congenital toxoplasmosis. Thus, in this study, we aimed to investigate the allelic and genotypic frequencies of specific single nucleotide polymorphisms (SNPs) in the IL17A and IL17RA genes, as well as the production of IL-17A, IL-33, and CCL2 in pregnant women, from the State of Rio Grande do Norte, Brazil, further relating these along with the clinical parameters, to the toxoplasmosis infection. Through PCR-RFLP techniques, two SNPs implicated in Th17 immune response, IL17A rs2275913 (G> A) and IL17RA rs4819554 (A> G) modulation were evaluated in pregnant women, either infected or not infected by T. gondii. These women were also evaluated in terms of plasma release of CCL2, IL-33, and IL-17A which relate to hypertension, number of abortions, and ethnic pattern. The results showed that the G-allele of the SNP rs2275913 (IL17A) appeared to be protective in this population, while the rs4819554 (IL17RA) SNP G allele was associated with greater susceptibility to T. gondii infection [ρ value = 0.025; OR = 2.815 (1.118-7.089); CI = 95%]. None of the cytokines had any influence on the analyzed parameters (abortion and hypertension). In conclusion, our data suggest an immunogenic evidence of susceptibility to T. gondii infection driven by the rs4819554 (IL17RA) SNP G allele in Brazilian pregnant women. Further studies are needed to reinforce this trial marker in populations from distinct geographical areas as well as to confirm the protective pattern related to the G-allele of the SNP rs2275913 (IL17A) in pregnant women.

Chronic Toxoplasma gondii infection contributes to decreasing of perineuronal nets surrounding neurons in the Corpus striatum of mice.

Recent advances in chronic toxoplasmosis understanding became the focus of discussion about behavioral abnormalities, which could be explained by cyst location and neuronal impairment in specific brain areas. Perineuronal nets (PNNs) are specialized extracellular matrices that surround the neuronal body and proximal dendrites and play key roles in neuronal circuitry maintenance and stabilization. Its impairment can lead to abnormal synaptic functioning with behavioral repercussions. In this context, we analyzed the impact of Toxoplasma gondii infection on neuronal integrity in the Corpus striatum of chronically infected mice. C57BL/6 and Balb/c female mice were infected with T. gondii ME49 cysts. Brain sections were submitted to immunohistochemistry with Wisteria floribunda agglutinin (WFA) for PNN labeling followed by quantification of tissue cyst and labeled neuronal cells 30 days after infection. Our results revealed that C57BL/6 exhibited a significant decrease in PNN-positive (WFA+) labeled neurons and an expressively higher number of tissue cysts than Balb/c mice. It was also possible to observe that the number of T. gondii tissue cysts and the number of WFA+ neurons were inversely correlated for C57BL/6-infected mice. However, no correlation was observed for Balb/c mice. These data suggest how the impact of parasite dissemination in the brain and host characteristics can influence neuronal integrity impairment during infection by decreasing WFA+ neurons. This might be a plausible pathway in which the presence of T. gondii contributes to behavioral changes in the infected host.

New endoperoxides highly active in vivo and in vitro against artemisinin-resistant Plasmodium falciparum.

BACKGROUND: The emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy in Southeast Asia prompted the need to develop new endoperoxide-type drugs. METHODS: A chemically diverse library of endoperoxides was designed and synthesized. The compounds were screened for in vitro and in vivo anti-malarial activity using, respectively, the SYBR Green I assay and a mouse model. Ring survival and mature stage survival assays were performed against artemisinin-resistant and artemisinin-sensitive P. falciparum strains. Cytotoxicity was evaluated against mammalian cell lines V79 and HepG2, using the MTT assay. RESULTS: The synthesis and anti-malarial activity of 21 new endoperoxide-derived compounds is reported, where the peroxide pharmacophore is part of a trioxolane (ozonide) or a tetraoxane moiety, flanked by adamantane and a substituted cyclohexyl ring. Eight compounds exhibited sub-micromolar anti-malarial activity (IC50 0.3-71.1 nM), no cross-resistance with artemisinin or quinolone derivatives and negligible cytotoxicity towards mammalian cells. From these, six produced ring stage survival < 1% against the resistant strain IPC5202 and three of them totally suppressed Plasmodium berghei parasitaemia in mice after oral administration. CONCLUSION: The investigated, trioxolane-tetrazole conjugates LC131 and LC136 emerged as potential anti-malarial candidates; they show negligible toxicity towards mammalian cells, ability to kill intra-erythrocytic asexual stages of artemisinin-resistant P. falciparum and capacity to totally suppress P. berghei parasitaemia in mice.

Seroepidemiological Survey of Canine Leishmania Infections from Peripheral Areas in Natal, Northeast Brazil.

BACKGROUND AND OBJECTIVE: Human visceral leishmaniasis is endemic in Natal, northeast of Brazil, where the domestic dog is an important parasite reservoir in the infectious cycle of Leishmania spp. In this study, was evaluated the antileishmanial IgG antibody and epidemiological factors related to canine visceral leishmaniasis (CVL). METHODS: Sera samples obtained by venipuncture of 1,426 dogs living in areas of human visceral leishmaniasis occurrence were tested for detection of IgG anti-leishmania antibodies with Immunofluorescence Antibody Assay (IFA) and Enzyme Linked Immunosorbent Assay (ELISA). Chi-square (x(2)) and Odds Ratio (OR) were calculated. Differences were considered statistically significant at p≤0.05. RESULTS: The overall seroprevalence was 10.30% (147/1,426); prevalence increased when the samples were found to be positive at least for one technique ([417/1,426] 29.3%). The high percentage of seroprevalence was observed in Nova República (15.35%), Nova Natal I (12.7%) and Lagoa Azul (11.4%) neighborhoods. In the Planalto, Soledade and Brasil Novo, the infection rates ranged from 7.5 at 8.06%. (p=0.00051). There was neither statistically significant difference between leishmanial infection nor clinical signs of disease (p=0.84; OR=1.0 [0.41; 2.3]), sex (p=0.78, OR=0.94 [0.66; 1.28]); and breed (p=0.92; OR=1.0 [0.65; 1.54]) were observed. CONCLUSION: The RESULTS suggest that CVL is widely distributed in Natal, may be increasingly urbanizing and will spread through neighborhoods but not endemic, resulting in a serious public health problem, emphasizing the need for epidemiological studies to a greater understanding of the distribution of canine leishmaniasis in these specific areas and contribute proactively to the public health policies.

In vivo antimalarial activity and mechanisms of action of 4-nerolidylcatechol derivatives.

4-Nerolidylcatechol (1) is an abundant antiplasmodial metabolite that is isolated from Piper peltatum roots. O-Acylation or O-alkylation of compound 1 provides derivatives exhibiting improved stability and significant in vitro antiplasmodial activity. The aim of this work was to study the in vitro inhibition of hemozoin formation, inhibition of isoprenoid biosynthesis in Plasmodium falciparum cultures, and in vivo antimalarial activity of several 4-nerolidylcatechol derivatives. 1,2-O,O-Diacetyl-4-nerolidylcatechol (2) inhibited in vitro hemozoin formation by up to 50%. In metabolic labeling studies using [1-(n)-(3)H]geranylgeranyl pyrophosphate, diester 2: significantly inhibited the biosynthesis of isoprenoid metabolites ubiquinone 8, menaquinone 4, and dolichol 12 in cultures of P. falciparum 3D7. Similarly, 2-O-benzyl-4-nerolidylcatechol (3) significantly inhibited the biosynthesis of dolichol 12. P. falciparum in vitro protein synthesis was not affected by compounds 2 or 3. At oral doses of 50 mg per kg of body weight per day, compound 2 suppressed Plasmodium berghei NK65 in infected BALB/c mice by 44%. This in vivo result for derivative 2 represents marked improvement over that obtained previously for natural product 1. Compound 2 was not detected in mouse blood 1 h after oral ingestion or in mixtures with mouse blood/blood plasma in vitro. However, it was detected after in vitro contact with human blood or blood plasma. Derivatives of 4-nerolidylcatechol exhibit parasite-specific modes of action, such as inhibition of isoprenoid biosynthesis and inhibition of hemozoin formation, and they therefore merit further investigation for their antimalarial potential.

In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the Amazonian plant Tachia grandiflora (Gentianaceae).

Tachia sp. are used as antimalarials in the Amazon Region and in vivo antimalarial activity of a Tachia sp. has been previously reported. Tachia grandiflora Maguire and Weaver is an Amazonian antimalarial plant and herein its cytotoxicity and antimalarial activity were investigated. Spectral analysis of the tetraoxygenated xanthone decussatin and the iridoid aglyone amplexine isolated, respectively, from the chloroform fractions of root methanol and leaf ethanol extracts was performed. In vitro inhibition of the growth of Plasmodium falciparum Welch was evaluated using optical microscopy on blood smears. Crude extracts of leaves and roots were inactive in vitro. However, chloroform fractions of the root and leaf extracts [half-maximal inhibitory concentration (IC50) = 10.5 and 35.8 µg/mL, respectively] and amplexine (IC50= 7.1 µg/mL) were active in vitro. Extracts and fractions were not toxic to type MRC-5 human fibroblasts (IC50> 50 µg/mL). Water extracts of the roots of T. grandiflora administered by mouth were the most active extracts in the Peters 4-day suppression test in Plasmodium berghei-infected mice. At 500 mg/kg/day, these extracts exhibited 45-59% inhibition five to seven days after infection. T. grandiflora infusions, fractions and isolated substance have potential as antimalarials.

In vivo antimalarial activity of novel 2-hydroxy-3-anilino-1,4-naphthoquinones obtained by epoxide ring-opening reaction.

1,4-Naphthoquinone derivatives are known to have relevant activities against several parasites. Among the treatment options for malaria, atovaquone, a 1,4-naphthoquinone derivative, is widely applied in the treatment and prophylaxis of such disease. Based on the structure simplification of atovaquone, we designed and synthesized four novel naphthoquinoidal derivatives. The compounds were obtained by the underexplored epoxide-opening reaction of 1,4-naphthoquinone using aniline derivatives as nucleophiles. The antiplasmodial activity of the synthesized compounds was performed in vivo using Peter's 4days suppression test. Significant parasitemia reduction and increased survival were observed for some of the compounds.

Toxoplasmosis screening and risk factors amongst pregnant females in Natal, northeastern Brazil.

Toxoplasmosis results in systemic disease, and if the mother is infected for the first time during gestation, the fetus may suffer substantial damage. Relatively little is known about the epidemiology of toxoplasmosis in pregnancy in most states of northeastern Brazil. Seroprevalence of toxoplasmosis among pregnant woman was studied in Natal, capital of Rio Grande do Norte State, in northeastern Brazil, from March to December 2007. The sera were tested for IgM and avidity of IgG antibodies to Toxoplasma by a microparticle enzyme immunoassay. The overall seroprevalence was high [126/190 (66.3%)]; prevalence increased with age indicating that in this setting most infections occur in adulthood (third decade of life). Only one pregnant woman was IgM positive and had high-avidity antibodies. The high percentage of pregnant women who are vulnerable to this parasite (33.1%) favors primary infection during pregnancy. Our studies show that direct contact with cats or dogs was highly associated with toxoplasmosis (odds ratio 2.72, P<0.001, 95% CI 1.46-5.02). The number of years in school (P<0.001), precarious socioeconomic status and limited knowledge about the disease (P

New antimalarial and cytotoxic 4-nerolidylcatechol derivatives.

4-Nerolidylcatechol (1) was isolated from cultivated Pothomorphe peltata root on a multigram scale using straight-forward solvent extraction-column chromatography. New semi-synthetic derivatives of 1 were prepared and tested in vitro against multidrug-resistant Plasmodium falciparum K1 strain. Mono-O-methyl, mono-O-benzyl, O,O-dibenzyl and O,O-dibenzoyl derivatives 2-8 exhibited IC(50) in the 0.67-22.52 microM range. Mono-O-methyl ethers 6 and 7 inhibited the in vitro growth of human tumor cell lines HCT-8 (colon carcinoma), SF-295 (central nervous system), LH-60 (human myeloblastic leukemia) and MDA/MB-435 (melanoma). In general, derivatives 2-8 are more stable to light, air and pH at ambient temperatures than their labile, natural precursor 1. These derivatives provide leads for the development of a novel class of antimalarial drugs with enhanced chemical and pharmacological properties.