Displaying publications 61 - 80 of 124 in total

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  1. Sahimin N, Lim YAL, Ariffin F, Behnke JM, Basáñez MG, Walker M, et al.
    Parasit Vectors, 2017 May 15;10(1):238.
    PMID: 28506241 DOI: 10.1186/s13071-017-2167-8
    BACKGROUND: The number of migrants working in Malaysia has increased sharply since the 1970's and there is concern that infectious diseases endemic in other (e.g. neighbouring) countries may be inadvertently imported. Compulsory medical screening prior to entering the workforce does not include parasitic infections such as toxoplasmosis. Therefore, this study aimed to evaluate the seroprevalence of T. gondii infection among migrant workers in Peninsular Malaysia by means of serosurveys conducted on a voluntary basis among low-skilled and semi-skilled workers from five working sectors, namely, manufacturing, food service, agriculture and plantation, construction and domestic work.

    METHODS: A total of 484 migrant workers originating from rural locations in neighbouring countries, namely, Indonesia (n = 247, 51.0%), Nepal (n = 99, 20.5%), Bangladesh (n = 72, 14.9%), India (n = 52, 10.7%) and Myanmar (n = 14, 2.9%) were included in this study.

    RESULTS: The overall seroprevalence of T. gondii was 57.4% (n = 278; 95% CI: 52.7-61.8%) with 52.9% (n = 256; 95% CI: 48.4-57.2%) seropositive for anti-Toxoplasma IgG only, 0.8% (n = 4; 95% CI: 0.2-1.7%) seropositive for anti-Toxoplasma IgM only and 3.7% (n = 18; 95% CI: 2.1-5.4%) seropositive with both IgG and IgM antibodies. All positive samples with both IgG and IgM antibodies showed high avidity (> 40%), suggesting latent infection. Age (being older than 45 years), Nepalese nationality, manufacturing occupation, and being a newcomer in Malaysia (excepting domestic work) were positively and statistically significantly associated with seroprevalence (P 

    Matched MeSH terms: Toxoplasma/immunology*; Toxoplasma/isolation & purification
  2. Hajissa K, Zakaria R, Suppian R, Mohamed Z
    Parasit Vectors, 2015;8:315.
    PMID: 26062975 DOI: 10.1186/s13071-015-0932-0
    Serological investigation remains the primary approach to achieve satisfactory results in Toxoplasma gondii identification. However, the accuracy of the native antigen used in the current diagnostic kits has proven to be insufficient as well as difficult to standardize, so significant efforts have been made to find alternative reagents as capture antigens. Consequently, multi-epitope peptides are promising diagnostic markers, with the potential for improving the accuracy of diagnostic kits. In this study, we described a simple, inexpensive and improved strategy to acquire such diagnostic markers. The study was aimed at producing novel synthetic protein consisting of multiple immunodominant epitopes of several T. gondii antigens.
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/immunology*
  3. Hajissa K, Zakaria R, Suppian R, Mohamed Z
    J Adv Vet Anim Res, 2019 Jun;6(2):174-182.
    PMID: 31453188 DOI: 10.5455/javar.2019.f329
    Despite the significant progress in the recent efforts toward developing an effective vaccine against toxoplasmosis, the search for new protective vaccination strategy still remains a challenge and elusive goal because it becomes the appropriate way to prevent the disease. Various experimental approaches in the past few years showed that developing a potential vaccine against the disease can be achievable. The combination of multi-epitopes expressing different stages of the parasite life cycle has become an optimal strategy for acquiring a potent, safe, and effective vaccine. Epitope-based vaccines have gained attention as alternative vaccine candidates due to their ability of inducing protective immune responses. This mini-review highlights the current status and the prospects of Toxoplasma gondii vaccine development along with the application of epitope-based vaccine in the future parasite immunization as a novel under development and evaluation strategy.
    Matched MeSH terms: Toxoplasma
  4. Thangarajah P, Hajissa K, Wong WK, Abdullah MA, Ismail N, Mohamed Z
    BMC Infect Dis, 2019 Feb 28;19(1):202.
    PMID: 30819141 DOI: 10.1186/s12879-019-3830-9
    BACKGROUND: Accurate diagnosis of Toxoplasma gondii (T. gondii) infection remains elusive and requires a comprehensive assessment through laboratory and clinical investigation. In this study, a diagnostic algorithm based on paired serum samples and clinical data was developed and evaluated.

    METHODS: A total of 1267 suspected cases of Toxoplasma infection were enrolled in this study from January 2016 to December 2016. The cases were screened for anti-Toxoplasma IgM and IgG by electrochemiluminiscence immunoassay (ECLIA) method. Based on the serological profiles, all cases with first seropositive serum samples were considered as suggestive cases of Toxoplasma infection. Thus, second serum samples were obtained after an interval of 2 weeks. The diagnosis was made based on laboratory results and clinical data.

    RESULTS: A total of 482 T. gondii seroreactive cases were selected. The patient's records were traced and the data were analysed. Accordingly, 152 cases were diagnosed as clinically confirmed cases; 198 cases were clinically asymptomatic and 132 cases were newborn babies or infants who did not have toxoplasmosis and only acquired passive immunity from their mothers. The paired serum algorithm allowed classifying the seroreactive cases as follows: early (0.6%), acute (1.9%), reactivation (13.5%), recent (1.5%), passive immunity from mother (27.3%) and possible congenital infections (1.2%). In addition, cases of reactivated toxoplasmosis were detected among the pregnant mothers (13/82; 15.8%), children aged above 1 year (2/8; 25.0%) and immunocompetent mothers (5/135; 3.7%). Furthermore, the application of the paired serum analysis resulted in remarkably improved treatment initiation.

    CONCLUSIONS: Toxoplasmosis diagnosis and treatment can be improved through the use of paired serum diagnostic algorithm.

    Matched MeSH terms: Toxoplasma
  5. Hajissa K, Zakaria R, Suppian R, Mohamed Z
    BMC Infect Dis, 2017 12 29;17(1):807.
    PMID: 29284420 DOI: 10.1186/s12879-017-2920-9
    BACKGROUND: The inefficiency of the current tachyzoite antigen-based serological assays for the serodiagnosis of Toxoplasma gondii infection mandates the need for acquirement of reliable and standard diagnostic reagents. Recently, epitope-based antigens have emerged as an alternative diagnostic marker for the achievement of highly sensitive and specific capture antigens. In this study, the diagnostic utility of a recombinant multiepitope antigen (USM.TOXO1) for the serodiagnosis of human toxoplasmosis was evaluated.

    METHODS: An indirect enzyme-linked immunosorbent assay (ELISA) was developed to evaluate the usefulness of USM.TOXO1 antigen for the detection of IgG antibodies against Toxoplasma gondii in human sera. Whereas the reactivity of the developed antigen against IgM antibody was evaluated by western blot and Dot enzyme immunoassay (dot-EIA) analysis.

    RESULTS: The diagnostic performance of the new antigens in IgG ELISA was achieved at the maximum values of 85.43% and 81.25% for diagnostic sensitivity and specificity respectively. The USM.TOXO1 was also proven to be reactive with anti- T. gondii IgM antibody.

    CONCLUSIONS: This finding makes the USM.TOXO1 antigen an attractive candidate for improving the toxoplasmosis serodiagnosis and demonstrates that multiepitope antigens could be a potential and promising diagnostic marker for the development of high sensitive and accurate assays.

    Matched MeSH terms: Toxoplasma/immunology*
  6. van Enter BJD, Lau YL, Ling CL, Watthanaworawit W, Sukthana Y, Lee WC, et al.
    Am J Trop Med Hyg, 2017 Jul;97(1):232-235.
    PMID: 28719309 DOI: 10.4269/ajtmh.16-0999
    Toxoplasma gondii primary infection in pregnancy is associated with poor obstetric outcomes. This study aimed to determine the seroprevalence of Toxoplasma infection in pregnant migrant and refugee women from Myanmar attending antenatal care in Thailand. A random selection of 199 residual blood samples from first antenatal screen in 2014-2015 was tested for Toxoplasma IgG and IgM antibodies. Seroprevalence of Toxoplasma infection was 31.7% (95% confidence interval = 25.6-38.4). Avidity testing in the three positive IgM cases indicated all were past infections. Multiparity (≥ 3 children) was significantly associated with higher Toxoplasma seropositivity rates. Seroprevalence of T. gondii infection in this pregnant population is similar to the only other report from Myanmar, where multiparity was also identified as a significant association. Toxoplasma infection is important in pregnant women. Nevertheless, in this marginalized population, this infection may be given less priority, due to resource constraints in providing the most basic components of safe motherhood programs.
    Matched MeSH terms: Toxoplasma/immunology*
  7. 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: Toxoplasma
  8. Tan DS, Mak JW
    PMID: 4023821
    Toxoplasmosis was found not to be an important cause of intrauterine infection in Malaysia as the rate of toxoplasma-specific IgM in 1,060 congenitally defective Malaysian children, 0 to 4 months old (0.4%) was lower than that in 405 normal children of the same age group (2.0%). A total of 8.2 intra-uterine toxoplasmic infections per 1,000 live births was detected of which one-third (2.7 per 1,000 live births) was overt, manifesting symptoms more of liver damage, than eye or brain damage. A comparison was made with the rates in U.S.A. and Europe. The role of toxoplasmosis in abortion needs to be studied.
    Matched MeSH terms: Toxoplasma/immunology
  9. Chew WK, Segarra I, Ambu S, Mak JW
    Antimicrob Agents Chemother, 2012 Apr;56(4):1762-8.
    PMID: 22271863 DOI: 10.1128/AAC.05183-11
    Toxoplasma gondii is a parasite that generates latent cysts in the brain; reactivation of these cysts may lead to fatal toxoplasmic encephalitis, for which treatment remains unsuccessful. We assessed spiramycin pharmacokinetics coadministered with metronidazole, the eradication of brain cysts and the in vitro reactivation. Male BALB/c mice were fed 1,000 tachyzoites orally to develop chronic toxoplasmosis. Four weeks later, infected mice underwent different treatments: (i) infected untreated mice (n = 9), which received vehicle only; (ii) a spiramycin-only group (n = 9), 400 mg/kg daily for 7 days; (iii) a metronidazole-only group (n = 9), 500 mg/kg daily for 7 days; and (iv) a combination group (n = 9), which received both spiramycin (400 mg/kg) and metronidazole (500 mg/kg) daily for 7 days. An uninfected control group (n = 10) was administered vehicle only. After treatment, the brain cysts were counted, brain homogenates were cultured in confluent Vero cells, and cysts and tachyzoites were counted after 1 week. Separately, pharmacokinetic profiles (plasma and brain) were assessed after a single dose of spiramycin (400 mg/kg), metronidazole (500 mg/kg), or both. Metronidazole treatment increased the brain spiramycin area under the concentration-time curve from 0 h to ∞ (AUC(0-∞)) by 67% without affecting its plasma disposition. Metronidazole plasma and brain AUC(0-∞) values were reduced 9 and 62%, respectively, after spiramycin coadministration. Enhanced spiramycin brain exposure after coadministration reduced brain cysts 15-fold (79 ± 23 for the combination treatment versus 1,198 ± 153 for the untreated control group [P < 0.05]) and 10-fold versus the spiramycin-only group (768 ± 125). Metronidazole alone showed no effect (1,028 ± 149). Tachyzoites were absent in the brain. Spiramycin reduced in vitro reactivation. Metronidazole increased spiramycin brain penetration, causing a significant reduction of T. gondii brain cysts, with potential clinical translatability for chronic toxoplasmosis treatment.
    Matched MeSH terms: Toxoplasma/drug effects
  10. 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: Toxoplasma/drug effects
  11. 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: Toxoplasma
  12. Mahdy MA, Alareqi LM, Abdul-Ghani R, Al-Eryani SM, Al-Mikhlafy AA, Al-Mekhlafi AM, et al.
    Infect Dis Poverty, 2017 Feb 13;6(1):26.
    PMID: 28190399 DOI: 10.1186/s40249-017-0243-0
    BACKGROUND: Toxoplasma gondii is a zoonotic coccidian parasite causing morbidity and mortality. In Yemen, T. gondii infection has been reported among pregnant women seeking healthcare in the main cities. However, no data are available on the prevalence of T. gondii infection and its associated risk factors among pregnant women in the rural communities of the country. Thus, the present study aimed to determine the seroprevalence of T. gondii and identify its risk factors among pregnant women in the rural communities of Taiz governorate, Yemen.

    METHODS: A total of 359 pregnant women living in the rural communities of Taiz governorate were enrolled in this study by house-to-house visits. Data were collected using a pre-designed questionnaire, and blood samples were collected and tested for the detection of anti- T. gondii IgM and IgG antibodies by enzyme-linked immunosorbent assay.

    RESULTS: The prevalence of T. gondii infection among pregnant women in this study was 46.2% (166/359). Bivariate analysis identified the age of  ≥ 30 years (odds ratio [OR] = 1.7; 95% confidence interval [CI] = 1.09-2.65, P = 0.019) and unimproved water sources (OR = 2.2; 95% CI = 1.10-4.55, P = 0.023) as factors associated with T. gondii infection among pregnant women. The multivariable analysis, however, identified unimproved water sources as an independent risk factor (adjusted OR = 2.4; 95% CI = 1.16-5.0, P = 0.018) associated with T. gondii infection among pregnant women.

    CONCLUSIONS: Pregnant women in the rural communities of Taiz, Yemen are at high risk of contracting T. gondii infection. Unimproved water sources (wells, water streams and water tanks) are significantly associated with T. gondii infection and should be considered in prevention and control strategies, especially among pregnant women.

    Matched MeSH terms: Toxoplasma/immunology
  13. Shen ZZ, Li K, Li ZJ, Shang XL, Hu F, Zhou WJ, et al.
    Trop Biomed, 2020 Jun 01;37(2):452-457.
    PMID: 33612814
    Toxoplasma gondii is a world-widely spread zoonotic parasite. However, scarce knowledge is known about the prevalence of T. gondii infection in people in Hubei province, China. This study herein was to perform epidemiological investigation of T. gondii infection in people in this region. A total 12527 blood samples were obtained during 2015-2018, and were assayed for T. gondii antibodies of IgG and IgM, respectively by employing an indirect hemagglutination test (IHA). The results discovered that the prevalence of T. gondii in people was 2.44% and 6.1%, respectively based on antibodies of IgG and IgM, respectively. The prevalence was ranged from 0.3% to 5.4% during 2015-2018 based on IgM antibodies. For genders, the prevalence was 0.7% and 2.6% in males and females, respectively based on IgM antibodies. In different years, the prevalence was ranged from 4.9% to 14.0% based on IgG antibodies. The prevalence of T. gondii was 4.9% and 6.6% in males and femalesy based on IgG antibodies. The current results may be helpful for the implementation of preventive measures against Toxoplasma infection among people living in this region.
    Matched MeSH terms: Toxoplasma
  14. Patrick S, Hui-Tze C, Wan-Hazabbah WH, Zunaina E, Azhany Y, Liza-Sharmini AT
    J Taibah Univ Med Sci, 2018 Oct;13(5):483-487.
    PMID: 31435366 DOI: 10.1016/j.jtumed.2018.03.005
    Management of inflammation after surgery for recalcitrant anterior uveitis is challenging. Herein, we report successful treatment using intracameral injection of recombinant tissue plasminogen activator (rtPA) in two patients with recalcitrant anterior uveitis, due to infective uveitis and Vogt-Koyanagi-Harada disease, respectively. A 40-year-old woman presented with bilateral redness and vision reduction that had persisted 2 weeks. She also had bilateral anterior uveitis, vasculitis, retinitis, and optic disc swelling. Serology was positive for Bartonella henselae and Toxoplasma gondii. She was treated using long-term systemic corticosteroids and appropriate antibiotics. Our second case; a healthy 30-year-old man with bilateral eye redness and reduced vision without pain, and associated with headache and tinnitus for 1 weeks. He showed bilateral granulomatous inflammation with vitritis, choroiditis, retinitis, and hyperemic optic disc. The patient was diagnosed with Vogt-Koyanagi-Harada disease and treated with systemic corticosteroids. Both patients developed secondary cataracts and glaucoma that necessitated surgical intervention. Persistent chronic inflammation led to the formation of a thick fibrin membrane anterior to the intraocular lens (IOL) after phacoemulsification surgery with IOL implantation. This membrane was removed surgically, and intracameral injection of rtPA (25 μg) was carried out. The persistent inflammation had resolved and visual acuity had significantly improved within 1 week of intracameral rtPA injection. There were no reported ocular or systemic side effects. Intracameral rtPA is beneficial in patients with recalcitrant anterior uveitis who have undergone intraocular surgery. In most cases, surgical intervention improves the patients' vision. Intracameral rtPA should be considered in cases of persistent inflammation of varying etiology.
    Matched MeSH terms: Toxoplasma
  15. Nimir AR, Linn TC
    Acta Medica (Hradec Kralove), 2011;54(3):107-10.
    PMID: 22250479
    The local Chow Kit market is the largest wet market in the city of Kuala Lumpur. It is very close to the biggest government hospital in the city centre. However, the level of cleanliness in this area is always questionable and a matter of concern. The aim of this study was to identify the prevalence of T. gondii oocyst in water samples used by hawkers in that market and tissue cysts in rats' brains captured from the same area. Water samples were taken to the parasitology laboratory at the National Universtiy of MalaysiaUniversity and a sugar flotation concentration method was used. Supernatant microscopical examination was then performed. A total of 752 slides were screened for the presence of T. gondii oocyst. A hundred rats wandering in the same area were also captured by the hawkers using mousetraps. After each animal was sacrificed, and an electric microtome was used to cut out serial sections 5 microm thick from the rat brains. The de-waxed tissue sections were stained by the progressive Haematoxylin and Eosin (H&E) stain for microscopical examination. A total of 1000 slides were screened under a light microscope to detect the presence of T. gondii brain cysts. All the water samples were found to be negative for T. gondii oocyst. Out of the 100 rats captured, three rats were found to possess T. gondii cysts in their brains. Water samples reflect minimal or no solid food contamination, while the 3% of positive brain cysts influence the researchers to broaden their investigations for future projects.
    Matched MeSH terms: Toxoplasma/isolation & purification*
  16. Ngui R, Hassan NA, Chang LY, Teh SJC, Chua KH, Kee BP, et al.
    Trop Biomed, 2020 Mar 01;37(1):155-164.
    PMID: 33612726
    Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis in humans. To date, little is known about T. gondii infection among the indigenous community, particularly in East Malaysia. This study was conducted to determine the status of T. gondii infection and to investigate associated risk factors among the indigenous community of Sarawak, East Malaysia. The sociodemographic data was obtained using a pretested questionnaire. A serological test was done to detect the presence of specific IgM and IgG antibodies against T. gondii in serum samples. A nested polymerase chain reaction (PCR) was used to determine acute infection among seropositive individuals. The overall seroprevalence of T. gondii infection was 50% (95% CI = 43.3 - 56.7). From this subset, 40.1%, 5.7%, and 4.2% were positive for anti-T. Gondii IgG antibodies, IgM, and both IgG and IgM, respectively. Four seropositive samples were amplified through PCR. None of the pregnant women tested positive for T. gondii infection based on the serological and PCR assays. A significant association was found between age, low monthly household income, unemployment, usage of untreated water and close contact with T. gondii seropositive cats. These results provide basic information on T. gondii infection and may be useful for policymakers to initiate prevention and control programs, especially amongst pregnant women and women of childbearing age in the indigenous community.
    Matched MeSH terms: Toxoplasma
  17. 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: Toxoplasma
  18. Sonaimuthu P, Fong MY, Kalyanasundaram R, Mahmud R, Lau YL
    Parasit Vectors, 2014;7:297.
    PMID: 24986686 DOI: 10.1186/1756-3305-7-297
    Toxoplasma gondii infects all warm-blooded animals, including humans. Early diagnosis and determining the infective stage are critical for effectively treating immunosuppressed individuals and pregnant women with toxoplasmosis. Among the rhoptry proteins of the parasite, Rhoptry protein 8 (ROP8), is known to be expressed during the early stages of T. gondii infection and is involved in parasitophorous vacuole formation. In this study, we have investigated the diagnostic efficacy of recombinant ROP8 (rROP8).
    Matched MeSH terms: Toxoplasma/metabolism*
  19. Parthasarathy S, Fong MY, Ramaswamy K, Lau YL
    Am J Trop Med Hyg, 2013 May;88(5):883-7.
    PMID: 23509124 DOI: 10.4269/ajtmh.12-0727
    Toxoplasmosis in humans and other animals is caused by the protozoan parasite Toxoplasma gondii. During the process of host cell invasion and parasitophorous vacuole formation by the tachyzoites, the parasite secretes Rhoptry protein 8 (ROP8), an apical secretory organelle. Thus, ROP8 is an important protein for the pathogenesis of T. gondii. The ROP8 DNA was constructed into a pVAX-1 vaccine vector and used for immunizing BALB/c mice. Immunized mice developed immune response characterized by significant antibody responses, antigen-specific proliferation of spleen cells, and production of high levels of IFN-γ (816 ± 26.3 pg/mL). Challenge experiments showed significant levels of increase in the survival period (29 days compared with 9 days in control) in ROP8 DNA vaccinated mice after a lethal challenge with T. gondii. Results presented in this study suggest that ROP8 DNA is a promising and potential vaccine candidate against toxoplasmosis.
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/immunology*; Toxoplasma/pathogenicity
  20. Chang PY, Fong MY, Nissapatorn V, Lau YL
    Am J Trop Med Hyg, 2011 Sep;85(3):485-9.
    PMID: 21896809 DOI: 10.4269/ajtmh.2011.11-0351
    Rhoptry protein 2 (ROP2) of Toxoplasma gondii is a rhoptry-secreted protein that plays a critical role in parasitophorous vacuole membrane formation during invasion. In previous studies, ROP2 has been shown to be efficient in triggering humoral and cell-mediated responses. High immunogenicity of ROP2 makes it a potential candidate for diagnosis and vaccination against toxoplasmosis. In this study, the ROP2 gene was cloned into pPICZα A expression vector and extracellularly expressed in the yeast Pichia pastoris, which has numerous advantages over other expression systems for eukaryotic proteins expression. The effectiveness of the secreted recombinant ROP2 as a diagnosis agent was assessed by Western Blot with 200 human serum samples. Recombinant ROP2 reacted with toxoplasmosis-positive human serum samples and yielded an overall sensitivity of 90% and specificity of 95%. However, recombinant ROP2 is a better marker for detection of IgG (91.7%) rather than IgM (80%).
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/metabolism*
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