Search Results (54)

Background/Objectives: Toxoplasmosis, a zoonotic disease caused by Toxoplasma gondii, typically is asymptomatic in immunocompetent individuals but causes severe complications in immunocompromised subjects and during pregnancy. Current treatments such as pyrimethamine and sulfadiazine are effective for acute infections but cannot eliminate encysted bradyzoites and have significant side effects. The antimicrobial killer peptide (KP) has interesting therapeutic potential, but its intracellular delivery is challenging; hyaluronate-based nanoparticles loaded with KP (KP-NPs) were evaluated to target T. gondii-infected cells that overexpress CD44. Methods: KP-NPs made of chitosan and hyaluronate were produced by microfluidics and were characterized for size, surface charge, encapsulation efficiency, and stability under stress conditions. After excluding their toxicity, their activity was tested in vitro against Candida albicans and T. gondii as free tachyzoite or in infected human foreskin fibroblasts (HFFs). Results: KP was efficiently encapsulated in nanoparticles and protected from harsh acidic conditions at high temperature. Preliminary in vitro testing against C. albicans showed that, at the lowest candidacidal concentration of KP (2.5 μg/mL), KP-NPs killed 90.97% of yeast cells. KP itself proved to be non-toxic for HFFs as host cells and effective against T. gondii. Comparable results were obtained for KP-NPs and blank nanoparticles (BLK-NPs), with no observed toxicity to host cells, confirming that encapsulation did not alter peptide efficacy. The parasiticidal effect of KP alone, as well as KP-NPs at 250 µg/mL and BLK-NPs, was confirmed through tests on free T. gondii tachyzoites. Reduction rates for the number of infected cells ranged from 66% to 90% with respect to control, while the reduction in the number of intracellular tachyzoites ranged from 66% to 80%. Interestingly, KP alone was not effective against intracellular tachyzoite, while KP-NPs maintained an efficacy comparable to the extracellular model, suggesting that particles helped the internalization of the peptide. Conclusions: Encapsulation of KP into hyaluronate/chitosan nanoparticles does not alter its activity and improves its efficacy against the intracellular parasite. Notably, BLK-NPs appeared to exhibit efficacy against the parasite on its own, without the presence of KP. Full article

Childbearing-aged and pregnant women represent a risk group for Toxoplasma gondii infection due to possible transplacental transmission resulting in congenital toxoplasmosis. We analyzed the seroepidemiological trends of toxoplasmosis in Croatia over ten years (2015–2024). A total of 2791 childbearing-aged and pregnant women were included. Toxoplasma gondii-specific IgM/IgG antibodies were detected using an enzyme-linked fluorescence assay. Samples with positive IgM and IgG antibodies were tested for IgG avidity. IgG antibodies were detected in 695 (24.9%) participants, while acute toxoplasmosis (IgM antibodies and low avidity IgG antibodies) was confirmed in 32 (1.2%) of participants. The IgG seroprevalence showed a declining trend over the years. Residents of suburban/rural areas were more often seropositive than those in urban areas (31.4 vs. 22.3%). Logistic regression analysis revealed that year of testing, age, and settlement were associated with the risk of seropositivity. For each later calendar year, the log odds of being IgG-positive decreased, while for each additional year of age, the log odds increased. Residence in an urban area was associated with lower log odds. The region was not a significant predictor in the logistic regression. The differences in seropositivity observed across regions can be mainly attributed to Pannonian Croatia, which showed significantly higher odds of IgG seropositivity. Data about the toxoplasma serological status is useful for planning prevention campaigns. Full article

Accurate dating of Toxoplasma gondii infection is essential for effective clinical management, particularly in pregnant women and immunocompromised individuals, where distinguishing acute from chronic infection informs treatment decisions. Serological detection of IgM antibodies is a key tool in diagnosing recent toxoplasmosis; however, its reliability is compromised by persistent IgM responses, cross-reactivity, and assay variability. While IgM lacks sufficient specificity to serve as a standalone marker of acute infection, it remains an important component of serological panels. This review summarizes current IgM detection methods and explores advancements aimed at improving diagnostic accuracy with a focus on recombinant antigens, which have emerged as promising alternatives to traditional Toxoplasma lysate antigen-based immunoassays. This paper also explores alternative methods of differentiating chronic and acute toxoplasmosis and outlines key areas for future research. Full article

Toxoplasmosis is a widely spread zoonosis worldwide, considered one of the most important parasitic infections that affect global public health, and usually, it is not correctly diagnosed. Serological tests for the diagnosis of Toxoplasma gondii infection have limitations in differentiating acute from chronic infection, which is important to determine the appropriate clinical management and treatment, mainly in pregnant women and immunocompromised individuals infected by this parasite. The present study aimed to characterize immunogenic epitopes from T. gondii immunodominant antigens, as SAG1(SRS29B), SAG2A (SRS34A), GRA1, GRA2, GRA3, GRA5, GRA6, GRA7, MAG1, BSR4, and CCp5A, by investigating if these parasite components might emerge as alternatives to improve the diagnosis of toxoplasmosis. A detailed comparative in silico analysis was used for this purpose. Once the protein sequences were retrieved from the ToxoDB database, different parameters were calculated, including physicochemical characteristics, accessibility values, and antigenicity. Multiple sequence alignment, 3D structures modeling, and the validation of 3D structures were also performed among all 11 peptides. Considering the results from the combination of all parameters analyzed, it can be hypothesized that the linear epitopes from SAG1, GRA3, and BSR4 proteins were found to be stable and hydrophilic, with a significant antigenicity score, and accessibility on the protein surface. Also, these three selected peptides were able to detect anti-T. gondii antibodies in serum samples from pigs infected by tachyzoites, when compared with control serum samples, obtained from the same naïve animals and tested by ELISA, demonstrating remarkable difference in terms of reactivity. Taken together, as our study addresses a critical challenge in the serodiagnosis of toxoplasmosis, particularly in gestational and congenital infections, where false-positive and false-negative results often arise from the use of native or recombinant antigens of T. gondii, our findings highlight the potential of synthetic peptides derived from novel epitopes of this parasite as alternative tools for the development of more accurate immunodiagnostic assays for toxoplasmosis. Full article

Passive maternal-fetal transfer of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies has been demonstrated, whilst the degree of transfer depending on the trimester of infection is lacking. Due to neonates’ immature immune systems, this knowledge could be of interest when investigating the degree of early-life protection against SARS-CoV-2. For perinatal infections such as Rubella and Toxoplasmosis, the timing of infection related to gestational age is crucial for the severity of maternal-fetal outcomes; hence, the trimester of SARS-CoV-2 infection could potentially be crucial. So far, there is no stratification on all three trimesters of SARS-CoV-2 infection in relation to maternal antibody levels in SARS-CoV-2 positive women, and the degree of transfer of SARS-CoV-2 antibodies to the newborn nor on obstetric and neonatal outcomes, which we examined in this study. Eleven departments in Denmark invited women who tested SARS-CoV-2 positive during pregnancy to participate with a blood sample and a cord blood sample at delivery. 459 SARS-CoV-2 positive women and 2567 SARS-CoV-2 negative women were included. A percentage of 87.5%, 95.3%, and 60.3% of newborns of women who tested positive in their first, second, and third trimester, respectively, had a significantly higher immunoglobin G (IgG) antibody level than their mother at delivery, indicating that the fetus is able to concentrate antibody levels or maintain the level of IgG antibodies transferred. None of the examined maternal-fetal outcomes were increased in women infected with SARS-CoV-2. Full article

Background: Toxoplasma gondii can cause congenital infections and abortions in humans. TgIST and TgNSM play critical roles in intracellular cyst formation and chronic infection. However, no studies have explored their potential to induce protective immunity against T. gondii infection. Objective: To evaluate the immune efficacy of DNA vaccines encoding TgNSM and TgIST genes against T. gondii infection, using the acute and chronic ME49 strain (Type II). Methods: DNA vaccines, including eukaryotic plasmids pVAX-IST and pVAX-NSM, were constructed. A cocktail DNA vaccine combining these two genes was formulated. The expression and immunogenicity were determined using the indirect immunofluorescence assay (IFA). Mice were immunized with DNA vaccines encoding either TgIST or TgNSM, as well as with the cocktail DNA vaccine. Humoral and cellular immune responses were analyzed by detecting antibody levels, cytotoxic T cell (CTL) responses, cytokines, and lymphocyte surface markers. Mouse survival and brain cyst counts were assessed 1 to 2 months post-vaccination in experimental toxoplasmosis models. The adjuvant efficacy of plasmid pVAX-IL-36γ in enhancing DNA vaccine-induced protective immunity was also evaluated. Results: DNA immunization with pVAX-IST and pVAX-NSM elicited strong humoral and cellular immune responses, characterized by increased Toxoplasma-specific IgG2a titers, Th1 responses (including production of IFN-γ, IL-2, IL-12p40, and IL-12p70), and cell-mediated activity with elevated frequencies of CD8+ and CD4+ T cells, and CTL responses. This provided significant protective efficacy against acute and chronic T. gondii infection. Mice immunized with the two-gene cocktail (pVAX-IST + pVAX-NSM) showed greater protection than those immunized with single-gene vaccines. Co-administration of the molecular adjuvant pVAX-IL-36γ further enhanced the protective immunity induced by the cocktail DNA vaccine. Conclusions: TgIST and TgNSM induce effective immunity against T. gondii infection, making them promising vaccine candidates against toxoplasmosis. Additionally, IL-36γ is a promising genetic adjuvant that enhances protective immunity in a vaccine setting against T. gondii, and it should be evaluated in strategies against other apicomplexan parasites. Full article

Toxoplasma gondii is an Apicomplexan parasite that is estimated to infect at least one-third of the global human population. T. gondii infection may be transmitted horizontally or vertically. The main risk factors for transmission to humans are related to diet, especially the consumption of undercooked meat, along with soil contact. In immunocompetent persons, the acute infection may go undetected as it typically produces minor, non-specific symptoms that are self-limited. After infection is established, recurrent retinochoroiditis is the most common clinical disease. In contrast, severe systemic or cerebral toxoplasmosis may be life-threatening for immunocompromised individuals. Furthermore, congenital toxoplasmosis acquired in utero may have devastating consequences if not recognized and promptly treated. A growing body of research has identified associations between latent T. gondii infection, and personality traits and risk-taking behaviors. Other studies have documented associations between latent infection and psychiatric conditions that include schizophrenia and bipolar affective disorder. With no current treatment regimens being curative of T. gondii infection, effective prevention measures at both the public health and individual levels are vitally important. Full article

During the COVID-19 pandemic, prenatal care services were disrupted. We analyzed the trajectory slopes of cases of congenital toxoplasmosis (CT) and acute toxoplasmosis during pregnancy from 2019 to 2022 (to reflect the cases during the pandemic years 2020–2022) vs. 2000 to 2019, using data from the Remington Laboratory, the National Reference Center for Toxoplasmosis in the US. During the pandemic, there was a statistically significant upward trajectory in the yearly number of CT cases. Monitoring of this trend is needed. Full article

Toxoplasma gondii (T. gondii) is an important zoonotic pathogen which induces both acute and chronic toxoplasmosis. Timely diagnosis of T. gondii is crucial for effective disease management. Here, we present a pioneering approach using europium (III)-chelated nanoparticles (EuNPs) in a rapid lateral flow immunochromatographic test strip (ICTS) for detecting T. gondii antibodies in serum samples. By conjugating EuNPs with Staphylococcus aureus protein A, we efficiently captured T. gondii-specific antibodies, which bound to T. gondii antigens on the test line (T-line), generating a distinct fluorescent signal. Employing this novel method, we conducted an extensive epidemiological investigation of T. gondii infections among dogs and cats in Shanghai, China. This innovative ICTS allows for rapid results within 25 min, which include a qualitative result through naked-eye observation under an ultraviolet lamp and a quantitative one derived using a strip reader. With a detection limit of 1:6400 for dog positive serum and no cross-reactivity with other canine and feline pathogens, the EuNPs-ICTS demonstrated excellent consistency with standard enzyme-linked immunosorbent assay results for dogs (κ = 0.91) and cats (κ = 0.92). In addition, 20.38% of 996 dog serum samples and 14.18% of 416 cat serum samples revealed T. gondii antibodies, highlighting the efficacy of this approach. Our study presents a rapid, sensitive, specific, and reproducible EuNPs-ICTS, serving as a promising tool for on-the-spot diagnosis of T. gondii infections in dogs and cats. Full article

Toxoplasmosis, a zoonotic infection caused by Toxoplasma gondii (T. gondii), poses a significant risk to human health and public safety. Despite the availability of clinical treatments, none effectively mitigate the intestinal barrier damage, which is the primary defense against T. gondii invasion. This study introduced aldehyde groups into the indole scaffold of a peptide-like structure to investigate the protective effects of these indole aldehyde derivatives on the intestinal barrier in mice with acute T. gondii infection. This approach leveraged the propensity of peptides and aldehyde groups to form hydrogen bonds. We synthesized a range of indole derivatives using the Vilsmeier–Haack reaction and evaluated their intestinal barrier protective effects both in vitro and in vivo. Our findings revealed that indole derivatives A1 (1-Formyl-1H-indole-3-acetonitrile), A3 (Indole-3-carboxaldehyde), A5 (2-Chloro-1H-indole-3-carboxaldehyde), A8 (1-Methyl-indole-3-carboxaldehyde), and A9 (1-Methyl-2-phenyl-1H-indole-3-carboxaldehyde) demonstrated a higher selectivity index compared to the positive control, spiramycin. These derivatives enhanced gastrointestinal motility, increased glutathione (GSH) levels in the small intestine, and reduced malondialdehyde (MDA) and nitric oxide (NO) levels in the small intestine tissue and diamine oxidase (DAO) and NO levels in the serum of infected mice. Notably, A3 exhibited comparable anti-T. gondii tachyzoites activity in the peritoneal cavity. Molecular docking studies indicated that the aldehyde group on the indole scaffold not only formed a hydrogen bond with NTPase-II but also interacted with TgCDPK1 through hydrogen bonding. Among the derivatives, A3 showed promising intestinal barrier protective effects in mice with acute T. gondii infection. This research suggests that indole derivatives could serve as a potential therapeutic strategy for intestinal diseases induced by T. gondii, offering a novel direction for treating intestinal barrier damage and providing valuable insights for the chemical modification of drugs targeting T. gondii. Furthermore, it contributes to the advancement of therapeutic approaches for toxoplasmosis. Full article

Toxoplasma gondii (T. gondii) is the causal agent of toxoplasmosis. It may produce severe damage in immunocompromised individuals, as well as congenital infection and intrauterine growth restriction (IUGR). Previous reports have associated interleukin IL-33 with miscarriage, fetal damage, and premature delivery due to infections with various microorganisms. However, IL-33 has not been associated with congenital toxoplasmosis. The sST2 receptor has been reported in patients who have had recurrent miscarriages. On the other hand, IL-1β was not found in acute Toxoplasma infection. Our aim was to analyze the associations between the serum levels of IL-33 and IL-1β in IUGR and toxoplasmosis during pregnancy. Eighty-four serum samples from pregnant women who had undergone 26 weeks of gestation were grouped as follows: with anti-Toxoplasma antibodies, without anti-Toxoplasma antibodies, IUGR, and the control group. IgG and IgM anti-T. gondii antibodies, as well as IL-33, ST2, and IL-1β, were determined using an ELISA assay. Statistical analyses were performed using the Pearson and Chi-square correlation coefficients, as well as the risk factors and Odds Ratios (ORs), with a confidence interval of 95% (CI 95). The results showed that 15/84 (17.8%) of cases were positive for IgG anti-Toxoplasma antibodies and 2/84 (2.38%) of cases were positive for IgM. A statistically significant difference was found between IUGR and IL-33 (p < 0.001), as well as between ST2 and IUGR (p < 0.001). In conclusion, IUGR was significantly associated with IL-33 and ST2 positivity based on the overall IUGR grade. No significant association was found between IUGR and the presence of anti-Toxoplasma antibodies. There was no association between IL-1β and IUGR. More research is needed to strengthen the utility of IL-33 and ST2 as biomarkers of IUGR. Full article

Toxoplasma gondii is the etiologic agent of toxoplasmosis, a highly prevalent parasitosis. Toxoplasma gondii (T. gondii) transits in the brain from acute (AT) to chronic toxoplasmosis (CT), under host immune control. In immunocompromised patients, reactivation of CT is potentially life-threatening. Behavioral and neurological complications have been associated with CT. Furthermore, an effective treatment targeting CT is still lacking. We previously reported the efficacy of imiquimod against CT. Here, we demonstrate the molecular effects of imiquimod or imiquimod followed by the clinically used combination of sulfadiazine and pyrimethamine (SDZ + PYR) on CT-associated behavior in a rat model. Imiquimod decreased the number of cysts in the brains of chronically infected rats due to an induced reactivation of bradyzoites into tachyzoites. Importantly, this decrease was more pronounced in rats treated with imiquimod followed by SDZ + PYR. Rats chronically infected with T. gondii exhibited an anxiety-like behavior. Notably, treatment with imiquimod reversed this behavior aberrancy, with even a more pronounced effect with imiquimod followed by SDZ/PYR. Similarly, rats chronically infected with T. gondii exhibited learning deficits, and imiquimod alone or followed by SDZ/PYR reversed this behavior. Our results enhance our knowledge of the implications of CT on behavioral aberrancies and highlight the potency of imiquimod followed by SDZ + PYR on these CT-associated complications. Full article

Toxoplasmosis is a significant global zoonosis with devastating impacts, and an effective vaccine against toxoplasmosis for humans has not yet been developed. In this study, we designed and formulated a novel DNA vaccine encoding the inhibitor of STAT1 transcriptional activity (IST) of T. gondii utilizing the eukaryotic expression vector pEGFP-N1 for the first time, with CL264 being a molecular adjuvant. Following intramuscular injection of the vaccine into mice, the levels of antibodies and cytokines were assessed to evaluate the immune response. Additionally, mice were challenged with highly virulent RH-strain tachyzoites of T. gondii, and their survival time was observed. The results show that the levels of IgG in serum, the ratio of IgG2a/IgG1 and the levels of IFN-γ in splenocytes of mice were significantly higher in the pEGFP-TgIST group and the pEGFP-TgIST + CL264 group than in the control group. In addition, the proportion of CD4+/CD8+ T cells was higher in mice immunized with either the pEGFP-TgIST group (p < 0.001) or the pEGFP-TgIST + CL264 group (p < 0.05) compared to the three control groups. Notably, TgIST-immunized mice exhibited prolonged survival times after T. gondii RH strain infection (p < 0.05). Our findings collectively demonstrate that the TgIST DNA vaccine elicits a significant humoral and cellular immune response and offers partial protection against acute T. gondii infection in the immunized mice, which suggests that TgIST holds potential as a candidate for further development as a DNA vaccine. Full article

Toxoplasmosis caused by Toxoplasma gondii is an important zoonosis of human and animal health significance. Current chemical therapeutics have side effects, and no commercially available vaccine is licensed for the prevention of toxoplasmosis in humans and most animals. Developing a safe and effective vaccine with long-term protection against T. gondii infection is necessary to control toxoplasmosis. HAD2a is a key member of the haloacid dehalogenase (HAD) phosphatase family, which is essential for T. gondii daughter budding. However, the role of HAD2a in T. gondii virulence remains unknown. In this study, we successfully constructed the had2a gene knockout strain in the T. gondii-type I RH strain (RHΔhad2a) and determined its role in virulence and vaccination. These results demonstrate that HAD2a played an important role in parasite daughter budding and in vitro replication. Knockout of the had2a gene attenuated the virulence of the T. gondii-type I RH strain. Vaccination with RHΔhad2a tachyzoites induced a Th1-biased immune response, provided partial protection against acute T. gondii infection in mice by highly virulent tachyzoites of RH and PYS (ToxoDB#9, Chinese I) strains, and conferred strong protection against challenge infection by cysts and oocysts of the less virulent type II Pru strain. These results demonstrate that T. gondii had2a is important for its in vitro proliferation and virulence in mice and that RHΔhad2a may be used as a candidate strain to generate a multiple gene knockout live-attenuated strain or be collaboratively applied with other live-attenuated strains to confer more effective protection against T. gondii infection. Full article

Vaccination is an ideal strategy for the control and prevention of toxoplasmosis. However, the thermostability and effectiveness of vaccines limit their application. Here, calcium mineralization was used to fabricate Toxoplasma gondii tachyzoites as immunogenic core–shell particles with improved immune response and thermostability. In the current study, T. gondii RH particles coated with mineralized shells were fabricated by calcium mineralization. The mineralized shells could maintain the T. gondii tachyzoites structural integrity for at least 12 months and weaken the virulence. Immunization of mice with mineralized tachyzoites induced high levels of T. gondii-specific antibodies and cytokines. The immunized mice were protected with a 100% survival rate in acute and chronic infection, and brain cyst burdens were significantly reduced. This study reported for the first time the strategy of calcium mineralization on T. gondii and proved that mineralized tachyzoites could play an immune protective role, thus expanding the application of biomineralization in T. gondii vaccine delivery. Full article