Displaying publications 1 - 20 of 141 in total

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  1. Thiruvengadam G, Init I, Fong MY, Lau YL
    Trop Biomed, 2011 Dec;28(3):506-13.
    PMID: 22433878 MyJurnal
    Surface antigens are the most abundant proteins found on the surface of the parasite Toxoplasma gondii. Surface antigen 1 (SAG1) and Surface antigen 2 (SAG2) remain the most important and extensively studied surface proteins. These antigens have been identified to play a role in host cell invasion, immune modulation, virulence attenuation. Recombinant SAG1/2 was cloned and expressed in yeast Pichia pastoris. We describe here optimization of critical parameters involved in high yield expression of the recombinant SAG1/2. Our results suggest that recombinant SAG1/2 were best expressed at 30ºC, pH 6 and 1% methanol as the carbon source by X33 Pichia cells. Additional optimizations included the downstream process such as ammonium sulphate precipitation and dialysis. The fusion protein was purified using Ni-NTA purification system with 80% recovery. The purified protein was 100% specific and sensitive in detection of toxoplasmosis.
    Matched MeSH terms: Toxoplasmosis/diagnosis
  2. Sonaimuthu P, Ching XT, Fong MY, Kalyanasundaram R, Lau YL
    Front Microbiol, 2016;7:808.
    PMID: 27303390 DOI: 10.3389/fmicb.2016.00808
    Toxoplasma gondii is the causative agent for toxoplasmosis. The rhoptry protein 1 (ROP1) is secreted by rhoptry, an apical secretory organelle of the parasite. ROP1 plays an important role in host cell invasion. In this study, the efficacy of ROP1 as a vaccine candidate against toxoplasmosis was evaluated through intramuscular or subcutaneous injection of BALB/c mice followed by immunological characterization (humoral- and cellular-mediated) and lethal challenge against virulent T. gondii RH strain in BALB/c mice. Briefly, a recombinant DNA plasmid (pVAX1-GFP-ROP1) was expressed in CHO cells while expression of recombinant ROP1 protein (rROP1) was carried out in Escherichia coli expression system. Immunization study involved injection of the recombinant pVAX1-ROP1 and purified rROP1 into different group of mice. Empty vector and PBS served as two different types of negative controls. Results obtained demonstrated that ROP1 is an immunogenic antigen that induced humoral immune response whereby detection of a protein band with expected size of 43 kDa was observed against vaccinated mice sera through western blot analysis. ROP1 antigen was shown to elicit cellular-mediated immunity as well whereby stimulated splenocytes with total lysate antigen (TLA) and rROP1 from pVAX1-ROP1 and rROP1-immunized mice, respectively, readily proliferated and secreted large amount of IFN-γ (712 ± 28.1 pg/ml and 1457 ± 31.19 pg/ml, respectively) and relatively low IL-4 level (94 ± 14.5 pg/ml and 186 ± 14.17 pg/ml, respectively). These phenomena suggested that Th1-favored immunity was being induced. Vaccination with ROP1 antigen was able to provide partial protection in the vaccinated mice against lethal challenge with virulent RH strain of tachyzoites. These findings proposed that the ROP1 antigen is a potential candidate for the development of vaccine against toxoplasmosis.
    Matched MeSH terms: Toxoplasmosis
  3. Andiappan H, Nissapatorn V, Sawangjaroen N, Khaing SL, Salibay CC, Cheung MM, et al.
    Front Microbiol, 2014;5:291.
    PMID: 24966855 DOI: 10.3389/fmicb.2014.00291
    Toxoplasma gondii, is one of the infectious agents of congenital TORCH infections, causes severe clinical outcomes in fetus and newborns. Nevertheless this life-threatening parasitic disease is preventable by simple preventive measures related to lifestyle during pregnancy. We aim to study on the knowledge about toxoplasmosis and practices that prevents this infection among the pregnant women. Total of 2598 pregnant women from Malaysia, Philippines, and Thailand were randomly surveyed to determine the knowledge and their practices on Toxoplasma infection. The questionnaire covered respondents' general information and knowledge on plausible risks factors, symptoms, timing of infection, prevention knowledge, and preventive behavior regarding Toxoplasma infection. Majority of these pregnant women were in their age group of 20-29 years (50.9%), completed secondary level of education (51.7%), in their second trimester of pregnancies (38.1%), non-parous (36.6%), and had no history of abortion (90.4%). Based on this survey, only 11% of these pregnant women had read, heard, or seen information regarding toxoplasmosis and 3.5% of them were aware of being tested for the infection. A small percentage of these pregnant women knew that T. gondii were shed in the feces of infected cats (19.4%) and sometimes found in the raw or undercooked meat (11.0%). There was 16.1% of responding women knew that toxoplasmosis is caused by an infection. Demographic profiles such as age group, level of education, pregnancy term, and number of children of the pregnant women showed significant association with their responses toward prevention knowledge and preventive behavior related questions (P < 0.05). Thus, it is suggested that health education on toxoplasmosis and primary behavioral practices should be consistently offered to reproductive age women in general and pregnant women in particular. This information could help to reduce vertical transmission of Toxoplasma infection during pregnancy.
    Matched MeSH terms: Toxoplasmosis
  4. Ching XT, Fong MY, Lau YL
    Front Microbiol, 2016;7:609.
    PMID: 27199938 DOI: 10.3389/fmicb.2016.00609
    Toxoplasmosis is a foodborne disease caused by Toxoplasma gondii, an obligate intracellular parasite. Severe symptoms occur in the immunocompromised patients and pregnant women leading to fatality and abortions respectively. Vaccination development is essential to control the disease. The T. gondii dense granule antigen 2 and 5 (GRA2 and GRA5) have been targeted in this study because these proteins are essential to the development of parasitophorous vacuole (PV), a specialized compartment formed within the infected host cell. PV is resistance to host cell endosomes and lysosomes thereby protecting the invaded parasite. Recombinant dense granular proteins, GRA2 (rGRA2) and GRA5 (rGRA5) were cloned, expressed, and purified in Escherichia coli, BL21 (DE3) pLysS. The potential of these purified antigens as subunit vaccine candidates against toxoplasmosis were evaluated through subcutaneous injection of BALB/c mice followed by immunological characterization (humoral- and cellular-mediated) and lethal challenge against virulent T. gondii RH strain in BALB/c mice. Results obtained demonstrated that rGRA2 and rGRA5 elicited humoral and cellular-mediated immunity in the mice. High level of IgG antibody was produced with the isotype IgG2a/IgG1 ratio of ≈0.87 (p < 0.001). Significant increase (p < 0.05) in the level of four cytokines (IFN-γ, IL-2, IL-4, and IL-10) was obtained. The antibody and cytokine results suggest that a mix mode of Th1/Th2-immunity was elicited with predominant Th1-immune response inducing partial protection against T. gondii acute infection in BALB/c mice. Our findings indicated that both GRA2 and GRA5 are potential candidates for vaccine development against T. gondii acute infection.
    Matched MeSH terms: Toxoplasmosis
  5. Brandon-Mong GJ, Che Mat Seri NA, Sharma RS, Andiappan H, Tan TC, Lim YA, et al.
    Front Immunol, 2015;6:143.
    PMID: 25972863 DOI: 10.3389/fimmu.2015.00143
    A cross-sectional study was conducted to determine the seroepidemiology of Toxoplasma infection and its risk association among people having close contact with animals. A total of 312 blood samples were collected from veterinary personnel (veterinarian, technicians, and students) and pet owners from veterinary clinics and hospitals in the area of Klang Valley, Malaysia. About 4 cc of blood samples drawn from agreed participants were processed for measurement of anti-Toxoplasma IgG and IgM antibodies as well as avidity test of Toxoplasma IgG by ELISA I, II, and III kits. Meanwhile, the demographic profiles and possible risk factors of these participants were also recorded in the standardized data collection sheets. Overall seroprevalence of toxoplasmosis was observed in 62 (19.9%) participants being 7 (18.4%) in veterinarians, 15 (33.3%) in veterinary technicians, 29 (14.9%) in veterinary students, and 11 (31.4%) in pet owners. Of 19.9% Toxoplasma seropositive samples, 18.3% was positive for IgG antibody, 1.0% for IgM antibody, and 0.6% for both IgG and IgM antibodies. Of three different IgG avidity ELISA kits, ELISA III showed high avidity in all five seropositive samples (IgM and IgG/IgM antibodies) indicating chronic Toxoplasma infection which is consistent with no evidence of clinical toxoplasmosis diagnosed during the time of this study. Univariate analysis showed that age group, gender, study population, gardening, task performance, and working duration were significantly associated with Toxoplasma seropositivity. Further analysis by multivariate analysis using logistic regression showed that age group of ≥30 years old (OR = 0.34, 95% CI = 0.18-0.63, p = 0.001) and working or study duration of >10 years having close contact with animals (OR = 5.07, 95% CI = 1.80-14.24, p = 0.002) were identified as significant risks for Toxoplasma infection. Based on the results obtained, a comprehensive Toxoplasma screening and health surveillance program on toxoplasmosis should be implemented among people having close contact with animals in general and confirmed Toxoplasma seronegative individuals in particular to prevent seroconversion.
    Matched MeSH terms: Toxoplasmosis
  6. Aisha Khodijah Kholib Jati, Suharni Mohamad, Zeehaida Mohamed, Wan Haslindawani Wan Mahmood, Wan Muhamad Amir W Ahmad, Wan Suriana Wan Ab Rahman1
    MyJurnal
    Introduction: This preliminary cross-sectional study aimed to investigate the prevalence of toxoplasmosis among blood donors in Kelantan, Malaysia. Methods: A total of 56 blood donors were screened by an enzyme-linked immu- nosorbent assay (ELISA) for anti-T. gondii Immunoglobulin G (IgG) and Immunoglobulin M (IgM) antibodies. Positive
    T. gondii IgG and IgM were further tested for IgG avidity ELISA. All extracted deoxyribonucleic acids (DNAs) from whole blood samples were analyzed for the presence of the Toxoplasma B1 gene and the ITS1 region by polymerase chain reaction (PCR). The socio-demographic data of donors was assessed using a data collection form. Results: Out of 56 blood donors, 24 (42.86%) donors were IgG+/IgM-, and 2 (3.57%) donors were IgG+/IgM+ with one of them having a high avidity index indicating as past infection for more than 20 weeks and the other with a low avidity index indicating as recent infection within 20 weeks. None of the samples tested positive for the presence of the Toxoplasma B1 gene and the ITS1 region. A univariate analysis showed that only employment status was significantly associated with Toxoplasma seropositivity. Conclusion: The seroprevalence of toxoplasmosis among blood donors in Kelantan, Malaysia, was 46.43%. Nevertheless, direct detection by PCR showed that this parasite was absent in the blood. These results highlight that the blood donors in this study had previously been exposed to T. gondii infection. The parasite may still remain in certain tissues but does not freely circulate in the blood.
    Matched MeSH terms: Toxoplasmosis
  7. Suresh S, Nor-Masniwati S, Nor-Idahriani MN, Wan-Hazabbah WH, Zeehaida M, Zunaina E
    Clin Ophthalmol, 2012;6:147-50.
    PMID: 22291456 DOI: 10.2147/OPTH.S26844
    BACKGROUND: The purpose of this study was to evaluate the immunoglobulin (Ig) G avidity of serological toxoplasmosis testing in patients with ocular inflammation and to determine the clinical manifestations of ocular toxoplasmosis.

    METHODS: A retrospective review of all patients presenting with ocular inflammation to the Hospital Universiti Sains Malaysia, Kelantan, Malaysia between 2005 and 2009 was undertaken. Visual acuity, clinical manifestations at presentation, toxoplasmosis antibody testing, and treatment records were analyzed.

    RESULTS: A total of 130 patients with ocular inflammation were reviewed retrospectively. The patients had a mean age of 38.41 (standard deviation 19.24, range 6-83) years. Seventy-one patients (54.6%) were found to be seropositive, of whom five (3.8%) were both IgG and IgM positive (suggestive of recently acquired ocular toxoplasmosis) while one (0.8%) showed IgG avidity ≤40% (suggestive of recently acquired ocular toxoplasmosis) and 65 patients (50.0%) showed IgG avidity >40% (suggestive of reactivation of toxoplasmosis infection). Chorioretinal scarring as an ocular manifestation was significantly more common in patients with seropositive toxoplasmosis (P = 0.036). Eighteen patients (13.8%) were diagnosed as having recent and/or active ocular toxoplasmosis based on clinical manifestations and serological testing.

    CONCLUSION: Ocular toxoplasmosis is a clinical diagnosis, but specific toxoplasmosis antibody testing helps to support the diagnosis and to differentiate between reactivation of infection and recently acquired ocular toxoplasmosis.

    Matched MeSH terms: Toxoplasmosis, Ocular
  8. Ullah MZ, Awais MM, Akhtar M, Anwar MI, Navid MT, Khan I, et al.
    Trop Biomed, 2018 Dec 01;35(4):1028-1040.
    PMID: 33601850
    Toxoplasmosis is a protozoal infection of zoonotic potential with worldwide geographical distribution which affects nearly all warm-blooded animals including mammals and birds. Keeping in view, this study was conducted to determine the seroprevalence of toxoplasmosis along with associated risk factors and its haematological impacts in small ruminants of district Multan, Pakistan. In this study, a total of 250 sera samples collected from sheep (n=125) and goats (n=125) from three tehsils of Multan were examined using commercially available Latex agglutination test kit for the presence of anti-T. gondii antibodies. The haematological profiles of Toxoplasma seropositive and seronegative animals were determined by using automated haematology analyser. Overall seroprevalence of toxoplasmosis in small ruminants was 42.80% with a higher prevalence rate (44.80%) in sheep as compared to goats (40.80%). Sex, existence of co-morbid conditions, feeding pattern and presence of pet cats and dogs were identified as significant (P<0.05) risk factors associated with the presence of antibodies against toxoplasmosis. The breed was found to be a significant (P=0.026) risk factor for the seroprevalence of toxoplasmosis in goats but not in sheep. Haematological analysis revealed significantly altered leukocytic counts (P<0.05) in seropositive sheep and goats as compared to seronegative ones. Our findings showed that small ruminants of the Multan District in Pakistan are toxoplasma seropositive and may pose a serious threat of public health concern in the region.
    Matched MeSH terms: Toxoplasmosis, Animal
  9. Kalantari N, Sheikhansari MR, Ghaffari S, Alipour J, Gorgani-Firouzjaee T, Tamadoni A, et al.
    Trop Biomed, 2018 Dec 01;35(4):1017-1027.
    PMID: 33601849
    T. gondii is a life-threatening infection in immunocompromised patients which may be transmitted through blood transfusion. The present study aimed to evaluate the seroprevalence and molecular detection of T. gondii infection and the associated risk factors among young healthy blood donors in the central part of Mazandaran province, northern Iran. Blood samples were taken from 500 participants and the serum was separated. All serum samples were tested for the presence of anti-T. gondii antibodies (IgG) and then all positive samples were evaluated for IgM antibodies using commercial ELISA kits. All IgM positive samples and 66 randomly selected IgG positive samples were further tested by PCR of the REP-529 gene. Anti-Toxoplasma antibodies (IgG) avidity test was performed for 142 IgG positive samples which were randomly selected. In the current study, anti-T. gondii antibodies (IgG) and (IgM) were found in 316 (63.2%) and 3 (0.95 %) participants, respectively. Seropositivity rate of Toxoplasma was higher among blood donors living in rural areas (P=0.000) and those with a history of soil and animal contact (P<0.05). PCR of the REP-529 gene showed T. gondii DNA in 21 out of 66 samples. The REP-529 gene was not detected in IgM positive samples. Low avidity antibodies (IgG) was found in 23.2% of the IgG positive samples. In conclusions, this study found that the prevalence of toxoplasmosis among young healthy blood donors in north of Iran was high. To reduce the risk of parasite transmission, leukofilteration method are recommended for donated blood used for immunosuppressed patients.
    Matched MeSH terms: Toxoplasmosis
  10. El Saftawy EA, Shash RY, Aboulhoda BE, Arsanyos SF, Albadawi EA, Abou-Fandoud SM, et al.
    Trop Biomed, 2021 Jun 01;38(2):53-62.
    PMID: 33973573 DOI: 10.47665/tb.38.2.037
    BACKGROUND: toxoplasmosis is a cosmopolitan protozoan disease with a wide range of neuropathology. Recent studies identified its potential association with several mental disorders e.g. schizophrenia dependable on apoptosis in their pathogenesis. We investigated value of toxoplasmosis to induce apoptosis of the neuronal cells.

    METHODS: per-orally infected C57BL/6 mice with 15-20 cysts of the avirulent T. gondii Beverly strain at 9-11 weeks of age were examined 12 weeks later during parasite establishment. Distributions of the parasite's cysts and the histopathological lesions in the brains were analyzed using Image J software. Relative expression of TNF-α and iNOS of cell-mediated immunity (CMI), Bax (pro-apoptosis) and Bcl-2 (anti-apoptosis) were all assessed using immunohistochemistry.

    RESULTS: higher parasite burden was seen in the forebrain with p value <= 0.05. Dramatically increased TNF-α, iNOS, and Bax expressions with Bax/Bcl-2 ratio 2.42:0.52 were reported (p value <= 0.05). The significant correlation between Bax data and different CMI biomarkers including TNF-α and i-NOS was evaluated. Interestingly, no significant correlation was seen between TNF-α, iNOS, Bax and Bcl-2 expressions and location of the parasite. However, Bax/Bcl-2 ratio was statistically correlated with CMI biomarkers and whole sample mean parasite burden, p value <= 0.05.

    CONCLUSION: Chronic toxoplasmosis exhibits an immense pro-apoptotic signal on the cerebral tissues of experimental mice.

    Matched MeSH terms: Toxoplasmosis
  11. Baha Latif
    Medical Health Reviews, 2009;2009(2):27-46.
    MyJurnal
    This review places emphasis on the food and water borne protozoal diseases like, cryptosporidiosis, giardiasis, cyclosporiasis, and toxoplasmosis which are endemic in many parts of the world. The article addresses cryptosporidiosis, giardiasis, cyclosporiasis, and toxoplasmosis. Cryptosporidium and Giardia are widespread in the environment and major outbreaks have occurred as a result of contaminated drinking water. Cyclospora has significance in the preparation and consumption of fresh food that have not received heat treatment. Toxoplasma gondii, transmission occur through contaminated water, unpasteurised milk and also the consumption of raw meat, which has been regarded as a major route of transmission to humans .These parasitic protozoa do not multiply in foods, but they may survive in or on moist foods for months especially in cool and damp environment. Their ecology makes control of these parasites difficult. Transmission, clinical manifestations, outbreaks, public health surveillance and control measures that are used for those diseases will be reviewed in this article.
    Matched MeSH terms: Toxoplasmosis
  12. Harun MSR, Taylor M, Zhu XQ, Elsheikha HM
    Microorganisms, 2020 Jun 04;8(6).
    PMID: 32512820 DOI: 10.3390/microorganisms8060842
    Central to the progression of cerebral toxoplasmosis is the interaction of Toxoplasma gondii with the blood-brain barrier (BBB) endothelial cells. In the present work, we tested the hypothesis that inhibition of Wnt pathway signalling by the monovalent ionophore monensin reduces the growth of T. gondii infecting human brain microvascular endothelial cells (hBMECs) or microglial cells. The anti-parasitic effect of monensin (a Wnt signalling inhibitor) on the in vitro growth of T. gondii tachyzoites was investigated using two methods (Sulforhodamine B staining and microscopic parasite counting). The monensin inhibited T. gondii growth (50% inhibitory concentration [IC50] = 0.61 μM) with a selective index = 8.48 when tested against hBMECs (50% cytotoxic concentration [CC50] = 5.17 μM). However, IC50 of monensin was 4.13 μM with a SI = 13.82 when tested against microglia cells (CC50 = 57.08 μM), suggesting less sensitivity of microglia cells to monensin treatment. The effect of T. gondii on the integrity of the BBB was assessed by the transendothelial electrical resistance (TEER) assay using an in vitro human BBB model. The results showed that T. gondii infection significantly decreased hBMECs' TEER resistance, which was rescued when cells were treated with 0.1 µM monensin, probably due to the anti-parasitic activity of monensin. We also investigated the host-targeted effects of 0.1 µM monensin on global gene expression in hBMECs with or without T. gondii infection. Treatment of hBMECs with monensin did not significantly influence the expression of genes involved in the Wnt signalling pathway, suggesting that although inhibition of the Wnt signalling pathway did not play a significant role in T. gondii infection of hBMECs, monensin was still effective in limiting the growth of T. gondii. On the contrary, monensin treatment downregulated pathways related to steroids, cholesterol and protein biosynthesis and their transport between endoplasmic reticulum and Golgi apparatus, and deregulated pathways related to cell cycle and DNA synthesis and repair mechanisms. These results provide new insight into the host-modulatory effect of monensin during T. gondii infection, which merits further investigation.
    Matched MeSH terms: Toxoplasmosis, Cerebral
  13. Sharif AA, Unyah NZ, Nordin N, Basir R, Wana MN, Alapid Ahmad A, et al.
    PMID: 31827548 DOI: 10.1155/2019/2916547
    Background: Toxoplasmosis remains widely distributed globally and is one of the major neglected parasitic zoonotic infections. The infection is still endemic in most parts of the world due to poor control as well as challenges of the currently used medications which can be overcome by using natural products. This study evaluated the effect of ethanolic extract from the stem of Tinospora crispa (EETC) on host cell invasion and intracellular replication of Toxoplasma gondii.

    Method: The stem powder of T. crispa was soaked in absolute ethanol for 72 hours. The resulting ethanolic extract was screened for the presence of phytochemicals. Vero cells monolayer in 96-well plate was infected with RH strain of T. gondii and treated with concentrations of the EETC, Veratrine alkaloid, and clindamycin ranging from 1.56 to 200 μg/mL. MTT assay was conducted after 24 hours to evaluate the cytotoxicity and antiparasitic activities of the EETC. Four and 24 hours treatment models were adapted to assess the infection index and intracellular proliferation of T.

    Results: The study revealed that the EETC had no cytotoxic effects on Vero cells with IC50 = 179 μg/mL, as compared to clindamycin (IC50 = 116.5 μg/mL) and Veratrine alkaloid (IC50 = 60.4 μg/mL). The EETC had good anti-toxoplasma activities with IC50 = 6.31 μg/mL in comparison with clindamycin (IC50 = 8.33 μg/mL) and Veratrine alkaloid (IC50 = 14.25 μg/mL). The EETC caused more than 70% and 80% reduction in infection index and intracellular proliferation in both treatment models, respectively.

    Conclusion: This in vitro study showed that the EETC contains promising phytochemicals effective against T. gondii and safe to the host cells.

    Matched MeSH terms: Toxoplasmosis
  14. Nissapatorn V, Lee C, Quek KF, Abdullah KA
    Jpn J Infect Dis, 2003 Oct-Dec;56(5-6):187-92.
    PMID: 14695428
    We retrospectively reviewed 419 HIV/AIDS patients in Hospital Kuala Lumpur from 1994 to 2001. In the male group, the age range was 20-74, with a mean age 37 years, while in the female group it was 17-63, with a mean age of 33 years. With regard to age group, it was found that the preponderant age group was 25-34 years. The majority of male subjects were Chinese (52.5%), single (56.3%), and unemployed (55.1%), whereas the females were Malay (42.3%), married (79.5%), and non-laborer (64.1%). Also, both groups resided in Kuala Lumpur and had heterosexual contact as the leading cause of HIV transmission. More than half of the patients had CD4 cell counts of <200 cells/cumm. We found that the acquisition of HIV infection via intravenous drug use (IDU) was directly related to the incidence of tuberculosis infection (P < 0.05). Further analysis showed HIV-related tuberculosis with IDU was also dependently correlated with occupational status (unemployed) (P < 0.05). The four main AIDS-defining diseases include tuberculosis (48%), Pneumocystis carinii pneumonia (13%), toxoplasmic encephalitis (11%), and cryptococcal meningitis (7%); in addition, 53% of these patients were found to have CD4 cell counts of less than 200 cells/cumm at the time of diagnosis.
    Matched MeSH terms: Toxoplasmosis, Cerebral/epidemiology
  15. Abdullahi SA, Unyah NZ, Nordin N, Basir R, Nasir WM, Alapid AA, et al.
    Mini Rev Med Chem, 2020;20(9):739-753.
    PMID: 31660810 DOI: 10.2174/1389557519666191029105736
    Identification of drug target in protozoan T. gondii is an important step in the development of chemotherapeutic agents. Likewise, exploring phytochemical compounds effective against the parasite can lead to the development of new drug agent that can be useful for prophylaxis and treatment of toxoplasmosis. In this review, we searched for the relevant literature on the herbs that were tested against T. gondii either in vitro or in vivo, as well as different phytochemicals and their potential activities on T. gondii. Potential activities of major phytochemicals, such as alkaloid, flavonoid, terpenoids and tannins on various target sites on T. gondii as well as other related parasites was discussed. It is believed that the phytochemicals from natural sources are potential drug candidates for the treatment of toxoplasmosis with little or no toxicity to humans.
    Matched MeSH terms: Toxoplasmosis/drug therapy*
  16. Lau YL, Hasan MT, Thiruvengadam G, Idris MM, Init I
    Trop Biomed, 2010 Dec;27(3):525-33.
    PMID: 21399595
    GRA4 of Toxoplasma gondii has been shown to prompt IgG, IgM and IgA responses in previous studies and is thus considered one of the major immunogenic proteins from T. gondii that can be used for both diagnostics purposes and vaccine development. This study seeks to clone and express the GRA4 in Pichia pastoris, which has numerous advantages over other systems for expression of eukaryotic proteins. In order to achieve this, the gene was cloned into the pPICZα A expression vector, which was then incorporated into the P. pastoris genome via insertional integration for expression of the recombinant protein, under the AOX1 promoter. The antigen was expressed along with the prepro sequence of the α-factor of yeast so that it could be excreted out of the P. pastoris cells and obtained from the medium. Upon SDS-PAGE analysis it was found that the recombinant protein was expressed optimally as a 40 kDa protein after 96 hours of induction with 0.75% of methanol. The expressed GRA4 protein showed discrepancy in size with the calculated molecular mass. This may be attributed to the various posttranslational modifications including glycosylation and phosphorylation. Despite the difference in molecular weight, the recombinant protein was able to detect toxoplasmosis in Western blot format. The recombinant GRA4 was expressed with an intact polyhistidine-tag, which could be used for future purification of the antigen.
    Matched MeSH terms: Toxoplasmosis/diagnosis*
  17. Lau YL, Fong MY
    Exp Parasitol, 2008 Jul;119(3):373-8.
    PMID: 18457835 DOI: 10.1016/j.exppara.2008.03.016
    The full length surface antigen 2 (SAG2) gene of the protozoan parasite Toxoplasma gondii was cloned and intracellularly expressed in the Pichia pastoris expression system. The molecular weight of the expressed recombinant SAG2 (36 kDa) was much larger than the native SAG2 (22 kDa). This discrepancy in size was due to hyperglycosylation, as deglycosylation assay reduced the size of the recombinant SAG2 to 22 kDa. Despite being hyperglycosylated, the recombinant SAG2 reacted strongly with pooled anti-Toxoplasma human serum, pooled anti-Toxoplasma mouse serum and a SAG2-specific monoclonal antibody. The glycosylated recombinant SAG2 was further evaluated in Western blot and in-house enzyme-linked immunosorbent assay (ELISA) using 80 human serum samples, including confirmed early acute (IgM positive, IgG negative; n=20), acute (IgM positive, IgG positive; n=20) and chronic (IgM negative, IgG positive; n=20) toxoplasmosis patients, and toxoplasmosis negative control patients (n=20). Results of the Western blot showed that the recombinant SAG2 reacted with all 60 samples of the toxoplasmosis cases but not with the Toxoplasma-negative samples. The sensitivity of in-house ELISA was 80%, 95% and 100% for early acute, acute and chronic patients' serum samples, respectively. Vaccination study showed that serum from mice immunised with the glycosylated recombinant SAG2 reacted specifically with the native SAG2 of T. gondii. The mice were significantly protected against lethal challenge with live T. gondii RH strain tachyzoites (P<0.01) and their survival time was increased compared to controls. Therefore, the present study shows that the P. pastoris-derived recombinant SAG2 was specific and suitable for use as antigen for detecting anti-Toxoplasma IgG and IgM antibodies. The vaccination study showed that recombinant SAG2 protein was immunoprotective in mice against lethal challenge.
    Matched MeSH terms: Toxoplasmosis, Animal/immunology; Toxoplasmosis, Animal/prevention & control
  18. Suresh K, Mak JW, Yong HS
    PMID: 1818401
    Matched MeSH terms: Toxoplasmosis, Animal/blood; Toxoplasmosis, Animal/immunology*
  19. Andiappan H, Nissapatorn V, Sawangjaroen N, Chemoh W, Lau YL, Kumar T, et al.
    Parasit Vectors, 2014;7:239.
    PMID: 24886651 DOI: 10.1186/1756-3305-7-239
    Toxoplasmosis, being one of the TORCH's infections in pregnant women, is caused by Toxoplasma gondii, an obligate intracellular protozoan parasite. This parasitic infection in pregnancy congenitally causes severe outcomes to their fetus and newborn. This study aimed to determine the seroprevalence and stages of Toxoplasma infection in pregnant women and its associated risks exposures.
    Matched MeSH terms: Toxoplasmosis/epidemiology*
  20. Amerizadeh A, Idris ZM, Khoo BY, Kotresha D, Yunus MH, Karim IZ, et al.
    Microb Pathog, 2013 Jan;54:60-6.
    PMID: 23044055 DOI: 10.1016/j.micpath.2012.09.006
    Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. Chronically-infected individuals with a compromised immune system are at risk for reactivation of the disease. In-vivo induced antigen technology (IVIAT) is a promising method for the identification of antigens expressed in-vivo. The aim of the present study was to apply IVIAT to identify antigens which are expressed in-vivo during T. gondii infection using sera from individuals with chronic toxoplasmosis. Forty serum samples were pooled, pre-adsorped against three different preparations of antigens, from each in-vitro grown T. gondii and Escherichia coli XLBlue MRF', and then used to screen a T. gondii cDNA expression library. Sequencing of DNA inserts from positive clones showed eight open reading frames with high homology to T. gondii genes. Expression analysis using quantitative real-time PCR showed that SAG1-related sequence 3 (SRS3) and two hypothetical genes were up-regulated in-vivo relative to their expression levels in-vitro. These three proteins also showed high sensitivity and specificity when tested with individual serum samples. Five other proteins namely M16 domain peptidase, microneme protein, elongation factor 1-alpha, pre-mRNA-splicing factor and small nuclear ribonucleoprotein F had lower RNA expression in-vivo as compared to in-vitro. SRS3 and the two hypothetical proteins warrant further investigation into their roles in the pathogenesis of toxoplasmosis.
    Matched MeSH terms: Toxoplasmosis/immunology*
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