Displaying publications 41 - 60 of 125 in total

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  1. Serological and molecular rapid diagnostic tests for Toxoplasma infection in humans and animals
    Khan AH, Noordin R
    Eur J Clin Microbiol Infect Dis, 2020 Jan;39(1):19-30.
    PMID: 31428897 DOI: 10.1007/s10096-019-03680-2
    Infection by Toxoplasma gondii is prevalent worldwide. The parasite can infect a broad spectrum of vertebrate hosts, but infection of fetuses and immunocompromised patients is of particular concern. Easy-to-perform, robust, and highly sensitive and specific methods to detect Toxoplasma infection are important for the treatment and management of patients. Rapid diagnostic methods that do not sacrifice the accuracy of the assay and give reproducible results in a short time are highly desirable. In this context, rapid diagnostic tests (RDTs), especially with point-of-care (POC) features, are promising diagnostic methods in clinical microbiology laboratories, especially in areas with minimal laboratory facilities. More advanced methods using microfluidics and sensor technology will be the future trend. In this review, we discuss serological and molecular-based rapid diagnostic tests for detecting Toxoplasma infection in humans as well as animals.
    Matched MeSH terms: Toxoplasma
  2. Fulltext High seroprevalence of echinococossis, schistosomiasis and toxoplasmosis among the populations in Babati and Monduli districts, Tanzania
    Khan MB, Sonaimuthu P, Lau YL, Al-Mekhlafi HM, Mahmud R, Kavana N, et al.
    Parasit Vectors, 2014;7:505.
    PMID: 25388913 DOI: 10.1186/s13071-014-0505-7
    The neglected tropical diseases, echinococcosis, schistosomiasis and toxoplasmosis are all globally widespread zoonotic diseases with potentially harmful consequences. There is very limited data available on the prevalence of these infections, except for schistosmiasis, in underdeveloped countries. This study aimed to determine the seroprevalence of Echinococcus multilocularis, Schistosoma mansoni, and Toxoplasma gondii antibodies in populations from the Monduli and Babati districts in Tanzania.
    Matched MeSH terms: Toxoplasma/immunology; Toxoplasma/isolation & purification
  3. Assessment of Euphorbia retusa and Pulicaria undulata activity against Leishmania major and Toxoplasma gondii
    Khan TA, Al Nasr IS, Mujawah AH, Koko WS
    Trop Biomed, 2021 Mar 01;38(1):135-141.
    PMID: 33797536 DOI: 10.47665/tb.38.1.023
    Leishmaniasis and toxoplasmosis are parasitic protozoal diseases that pose serious health concerns, especially for immunocompromised people. Leishmania major and Toxoplasma gondii are endemic in Saudi Arabia and are particularly common in the Qassim Region. The present work was conducted to evaluate the in vitro antileishmanial and antitoxoplasmal activity of methanolic extracts and phytochemical fractions from two plants, Euphorpia retusa and Pulicaria undulata, which are ethnobotanical agents used to treat parasitic infection. Whole E. retusa and P. undulata plants were extracted with methanol and fractionated using petroleum ether, chloroform, ethyl acetate, n-butanol, and water and then were tested in vitro against L. major promastigote and the amastigote stages of T. gondii; the cytotoxicity of the extracts was tested against Vero cell line. The methanolic extracts of E. retusa and P. undulata exhibited promising antitoxoplasmal activity against T. gondii with EC50 values 5.6 and 12.7 μg mL-1, respectively. The chloroform fraction of P. undulata was the most potent, exhibiting an EC50 of 1.4 μg mL-1 and SI value of 12.1. It was also the most active fraction against both L. major promastigotes and amastigotes, exhibiting an EC50 of 3.9 and 3.8 μg mL-1 and SI values 4.4 and 4.5, respectively. The chloroform fraction from P. undulata is a very good candidate for the isolation of active antitoxoplasmal and antileishmanial ingredients; therefore, further phytochemical analysis for active compound isolation is highly recommended.
    Matched MeSH terms: Toxoplasma/drug effects*
  4. Fulltext Recombinant proteins from new constructs of SAG1 and GRA7 sequences and their usefulness to detect acute toxoplasmosis
    Kotresha D, Poonam D, Muhammad Hafiznur Y, Saadatnia G, Nurulhasanah O, Sabariah O, et al.
    Trop Biomed, 2012 Mar;29(1):129-37.
    PMID: 22543613 MyJurnal
    In this study we have cloned unreported gene fragments of Toxoplasma gondii GRA7 and SAG1 and expressed the corresponding recombinant proteins, followed by evaluation of their usefulness for the serological diagnosis of toxoplasmosis. Both recombinant proteins were expressed efficiently in insoluble form, purified by single step Ni-NTA affinity chromatography and their antigenicity to detect toxoplasma specific IgG antibodies were determined by immunoblotting. A total of 60 serum samples from three groups of individuals based on their anti-toxoplasma antibody profiles were tested, namely (I) IgM+, IgG+ (n=20), (II) IgM-, IgG+ (n=20) and (III) IgM-, IgG- (n=20). Both recombinant proteins exhibited high sensitivity (100%) with sera from Group I. rGRA7 and rSAG1 reacted 40% and 80% respectively with Group II sera. The specificity of the recombinant proteins based on reactivities with Group III sera were 100% and 80% with rGRA7 and rSAG1 respectively. Thus rGRA7 was found to be better at discriminating probable acute from chronic phases of toxoplasmosis, and it also showed higher specificity.
    Matched MeSH terms: Toxoplasma/genetics
  5. Identification of Host Proteins Interacting with Toxoplasma gondii SAG1 by Yeast Two-Hybrid Assay
    Lai MY, Abdul-Majid N, Lau YL
    Acta Parasitol, 2019 Sep;64(3):575-581.
    PMID: 31165984 DOI: 10.2478/s11686-019-00066-4
    Toxoplasma gondii is one of the most successful human pathogens. To eliminate the infection, identification of receptors or binding partners from humans is indeed urgent. T. gondii surface antigen is the ultimate component involved during the attachment of parasite into host cell. However, mechanism of invasion between SAG and host-cell membrane remains unclear. Yeast two-hybrid experiment was used to identify the binding partners from cDNA human library by using T. gondii SAG1 as bait. Mated yeast cells were plated on DDO/X plates to confirm only prey plasmid that expressing interacting protein was selected. We detected 39 clones interacted with SAG1 based on a series of the selection procedures. After colony PCR, only 29 clones were positive and subsequently sent for sequencing. The yeast plasmids for true positive clones were rescued by transformation into E. coli TOP 10F' cells. Twenty-two clones were further examined by small-scale Y2H experiment. The results indicated that a strong interaction existed between Homo sapiens lysine-rich coil-coiled and SAG1 protein, which could activate the expressions of the reporter genes in diploid yeast. Co-immunoprecipitation experiment result indicated the binding between this prey and SAG1 protein was significant (Mann-Whitney U test, Z = - 1.964, P = 0.05). H. sapiens lysine-rich coil-coiled protein was found to be interacted with SAG1. This prey protein may serve as the potential drug target in vaccination study.
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/metabolism*
  6. Screening and identification of host proteins interacting with Toxoplasma gondii SAG2 by yeast two-hybrid assay
    Lai MY, Lau YL
    Parasit Vectors, 2017 Oct 02;10(1):456.
    PMID: 28969712 DOI: 10.1186/s13071-017-2387-y
    BACKGROUND: The identification of receptors or binding partners of Toxoplasma gondii from humans is an essential activity. Many proteins involved in T. gondii invasion have been characterized, and their contribution for parasite entry has been proposed. However, their molecular interactions remain unclear.

    RESULTS: Yeast two-hybrid (Y2H) experiment was used to identify the binding partners of surface antigens of T. gondii by using SAG2 as bait. Colony PCR was performed and positive clones were sent for sequencing to confirm their identity. The yeast plasmids for true positive clones were rescued by transformation into E. coli TOP 10F' cells. The interplay between bait and prey was confirmed by β-galactosidase assay and co-immunoprecipitation experiment. We detected 20 clones interacting with SAG2 based on a series of the selection procedures. Following the autoactivation and toxicity tests, SAG2 was proven to be a suitable candidate as a bait. Thirteen clones were further examined by small scale Y2H experiment. The results indicated that a strong interaction existed between Homo sapiens zinc finger protein and SAG2, which could activate the expressions of the reporter genes in diploid yeast. Co-immunoprecipitation experiment result indicated the binding between this prey and SAG2 protein was significant (Mann-Whitney U-test: Z = -1.964, P = 0.05).

    CONCLUSIONS: Homo sapiens zinc finger protein was found to interact with SAG2. To improve the understanding of this prey protein's function, advanced investigations need to be carried out.

    Matched MeSH terms: Toxoplasma
  7. Fulltext Determination of the specificities of monoclonal and polyclonal antibodies to Neospora, Toxoplasma and Cryptosporidium by fluorescent antibody test (FAT)
    Latif BM, Jakubek EB
    Trop Biomed, 2008 Dec;25(3):225-31.
    PMID: 19287361
    Flourescent antibody test (FAT) was applied to determine the cross-reactivities of monoclonal (mAb), polyclonal (pAb) antibodies to Neospora, Toxoplasma and Cryptosporidium and antisera from cattle naturally infected with Neospora canium against antigens from a number of sources. Both mAb and pAb to Neospora reacted strongly (FAT titre up to 2560) with the homologous antigens and demonstrated weak titre (80) or no reaction with both Toxoplasma and Cryptosporidium antigens. Also mAb and pAb to Toxoplasma gondii reacted at titres of 80 - 640 with homologous antigens and at titres of 10-40 with N. caninum. No cross-reactions with either mAb or pAb antibodies to N. caninum and T. gondii were observed with Cryptosporidium parvum. The same results were observed with C. parvum mAb when tested with both N. caninum and T. gondii antigens. Sera from cattle naturally infected with N. caninum had titres ranging from 80- 640 with N. caninum antigens, and 10- 40 with T. gondii and C. parvum antigens. At low dilutions, the complete surfaces of Neospora and Toxoplasma parasites were fluorescent, while in higher dilutions only dotted fluorescence appeared on the apical complex. These results indicated the presence of cross-reactivity between Neospora and Toxoplasma but not with Cryptosporidium. Accordingly the recommended cut-off antibody titre for diagnosis of neosporosis is 80.
    Matched MeSH terms: Toxoplasma/immunology*
  8. Immunogenic characterization of the chimeric surface antigen 1 and 2 (SAG1/2) of Toxoplasma gondii expressed in the yeast Pichia pastoris
    Lau YL, Thiruvengadam G, Lee WW, Fong MY
    Parasitol Res, 2011 Sep;109(3):871-8.
    PMID: 21455621 DOI: 10.1007/s00436-011-2315-6
    In this study, we successfully expressed a chimerical surface antigen 1 and 2 (SAG1/2) of Toxoplasma gondii in Pichia pastoris. Eighty human serum samples, including 60 from confirmed cases of toxoplasmosis, were tested against the purified recombinant SAG1/2 in Western blots. Results of Western blots targeted at Toxoplasma IgG and IgM showed that the recombinant SAG1/2 reacted with all sera from the toxoplasmosis cases but none with the Toxoplasma-negative serum samples. These results showed that the P. pastoris-derived recombinant SAG1/2 was sensitive and specific and suitable for use as antigen for detecting anti-Toxoplasma antibodies. To further investigate the immunological characteristic of the recombinant protein, the recombinant SAG1/2 was injected subcutaneously into BALB/c mice, and their serum was tested against total protein lysate of T. gondii. Mice immunized with the recombinant SAG1/2 reacted specifically with the native SAG1 and SAG2 of T. gondii. Significant proliferation of splenocytes stimulated with tachyzoite total protein lysate was observed in vaccinated BALB/c mice but not in those from negative control mice. Specific production of IFN-γ, the Th1-type cytokines, was also found in stimulated splenocytes from vaccinated mice. These results show that the chimeric protein recombinant SAG1/2 can elicit a Th1-associated protection against T. gondii infections in mice. Finally, vaccinated mice were significantly protected against lethal challenge with live T. gondii RH strain tachyzoites (P 
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/immunology*
  9. Toxoplasma gondii: serological characterization and immunogenicity of recombinant surface antigen 2 (SAG2) expressed in the yeast Pichia pastoris
    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: Toxoplasma/genetics; Toxoplasma/immunology*
  10. Fulltext Cloning and expression of Toxoplasma gondii dense granular protein 4 (GRA4) in Pichia pastoris
    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: Toxoplasma/genetics*
  11. Fulltext Characterisation of a truncated Toxoplasma gondii surface antigen 2 (SAG2) secreted by the methylotrophic yeast Pichia pastoris
    Lau YL, Shamilah H, Fong MY
    Trop Biomed, 2006 Dec;23(2):186-93.
    PMID: 17322821 MyJurnal
    A truncated form of surface antigen 2 (SAG2) of the protozoan parasite Toxoplasma gondii was cloned and expressed in the methylotrophic yeast Pichia pastoris. This recombinant antigen, designated as recSAG2-N, contained only the N-terminal half of the native SAG2. The recSAG2-N was secreted by the Pichia pastoris into the culture supernatant, and it was harvested by using the trichloroacetic acid precipitation method. Specificity of recSAG2-N was evaluated in western blot assays. Fifty human serum samples, including 32 from confirmed cases of toxoplasmosis, were tested. Results from the assays showed that recSAG2-N reacted with sera from the toxoplasmosis cases only. In vivo experiments showed that serum from mice which received recSAG2-N reacted with the native SAG2 of T. gondii.
    Matched MeSH terms: Toxoplasma*; Toxoplasmosis/diagnosis
  12. Fulltext Deciphering the Draft Genome of Toxoplasma gondii RH Strain
    Lau YL, Lee WC, Gudimella R, Zhang G, Ching XT, Razali R, et al.
    PLoS One, 2016;11(6):e0157901.
    PMID: 27355363 DOI: 10.1371/journal.pone.0157901
    Toxoplasmosis is a widespread parasitic infection by Toxoplasma gondii, a parasite with at least three distinct clonal lineages. This article reports the whole genome sequencing and de novo assembly of T. gondii RH (type I representative strain), as well as genome-wide comparison across major T. gondii lineages. Genomic DNA was extracted from tachyzoites of T. gondii RH strain and its identity was verified by PCR and LAMP. Subsequently, whole genome sequencing was performed, followed by sequence filtering, genome assembly, gene annotation assignments, clustering of gene orthologs and phylogenetic tree construction. Genome comparison was done with the already archived genomes of T. gondii. From this study, the genome size of T. gondii RH strain was found to be 69.35Mb, with a mean GC content of 52%. The genome shares high similarity to the archived genomes of T. gondii GT1, ME49 and VEG strains. Nevertheless, 111 genes were found to be unique to T. gondii RH strain. Importantly, unique genes annotated to functions that are potentially critical for T. gondii virulence were found, which may explain the unique phenotypes of this particular strain. This report complements the genomic archive of T. gondii. Data obtained from this study contribute to better understanding of T. gondii and serve as a reference for future studies on this parasite.
    Matched MeSH terms: Toxoplasma/genetics*
  13. Fulltext Specific, sensitive, and rapid diagnosis of active toxoplasmosis by a loop-mediated isothermal amplification method using blood samples from patients
    Lau YL, Meganathan P, Sonaimuthu P, Thiruvengadam G, Nissapatorn V, Chen Y
    J Clin Microbiol, 2010 Oct;48(10):3698-702.
    PMID: 20660217 DOI: 10.1128/JCM.00462-10
    Loop-mediated isothermal amplification (LAMP), a rapid nucleic acid amplification method, was developed for the clinical diagnosis of toxoplasmosis. Three LAMP assays based on the SAG1, SAG2, and B1 genes of Toxoplasma gondii were developed. The sensitivities and specificities of the LAMP assays were evaluated by comparison with the results of conventional nested PCR. The LAMP assays were highly sensitive and had a detection limit of 0.1 tachyzoite, and no cross-reactivity with the DNA of other parasites was observed. Blood was collected from 105 individuals to test the LAMP assays: 40 patients with active toxoplasmosis, 40 negative controls, and 25 patients with other parasitic infections. The SAG2-based LAMP (SAG2-LAMP) had a greater sensitivity (87.5%) than the SAG1-LAMP (80%), B1-LAMP (80%), and nested PCR (62.5%). All the LAMP assays and nested PCR were 100% specific. This is the first report of a study which applied the LAMP method to diagnose toxoplasmosis from human blood samples. Due to its simplicity, sensitivity, and specificity, LAMP is suggested as an appropriate method for routine diagnosis of active toxoplasmosis in humans.
    Matched MeSH terms: Toxoplasma/genetics; Toxoplasma/isolation & purification*
  14. Neonatal hepatitis among Malaysian infants
    Lee, W.S., Boey, C.C.M., Koh, M.T.
    Malaysian Journal of Child Health, 1998;10(1):40-45.
    MyJurnal
    From November 1996 to December 1997, 24 infants with neonatal cholestasis were referred to the Department of Paediatrics, University of Malaya Medical Center, Kuala Lumpur for further investigations. Nineteen had neonatal hepatitis. There was considerable delay in referral of infants with cholestasis; the mean age of referral was 63.7 days. None had a positive family history of neonatal hepatitis. All infant had hepatomegaly and ten had splenomegaly. The stools were slightly pale in thirteen, persistently acholic in three and normally pigmented in three infants. Liver synthetic functions were normal in most of the infants. Cytomegalovirus (CMV) IgM antibodies were positive in seven but none were positive for toxoplasma or rubella. al - antitrypsin deficiency, hypothyroidism, and galactosaemia were excluded in all infants. DISIDA scans were performed in seventeen infants, being non-excretory in eight. Liver biopsies were performed in fifteen infants, showing neonatal hepatitis in fourteen, while histological features of large duct obstruction was seen in one. In majority of infants (eight out of ten) the jaundice disappeared by six months. Two infants had progressive jaundice and liver function impairment.
    Matched MeSH terms: Toxoplasma
  15. Immune Stimulation of RAP domain binding protein (rTgRA15) from Toxoplasma gondii
    Lew MH, Noordin R, Monsur Alam Khan M, Tye GJ
    Pathog Glob Health, 2018 10;112(7):387-394.
    PMID: 30332344 DOI: 10.1080/20477724.2018.1536854
    Toxoplasmosis, a parasitic disease in human and animals, is caused by Toxoplasma gondii. Our previous study has led to the discovery of a novel RAP domain binding protein antigen (TgRA15), an apparent in-vivo induced antigen recognised by antibodies in acutely infected individuals. This study is aimed to evaluate the humoral response and cytokine release elicited by recombinant TgRA15 protein in C57BL/6 mice, demonstrating its potential as a candidate vaccine for Toxoplasma gondii infection. In this study, the recombinant TgRA15 protein was expressed in Escherichia coli, purified and refolded into soluble form. C57BL/6 mice were immunised intradermally with the antigen and CASAC (Combined Adjuvant for Synergistic Activation of Cellular immunity). Antigen-specific humoral and cell-mediated responses were evaluated using Western blot and ELISA. The total IgG, IgG1 and IgG2a antibodies specific to the antigen were significantly increased in treatment group compare to control group. A higher level of interferon gamma (IFN-γ) secretion was demonstrated in the mice group receiving booster doses of rTgRA15 protein, suggesting a potential Th1-mediated response. In conclusion, the rTgRA15 protein has the potential to generate specific antibody response and elicit cellular response, thus potentially serve as a vaccine candidate against T. gondii infection.
    Matched MeSH terms: Toxoplasma/immunology*
  16. Parasites in soil samples from Signy island, Antarctica
    Lim PKC, Lee XC, Mohd Nazmi NMA, Tang YY, Wong SF, Mak JW, et al.
    Trop Biomed, 2018 Dec 01;35(4):1007-1016.
    PMID: 33601848
    Studies on parasite populations in Antarctic soils are scarce and thus little is known about the threat of these parasites towards either the natural fauna or human visitors. However, human presence in Antarctica, mainly through research and tourism, keeps increasing over time, potentially exposing visitors to zoonotic infections from Antarctic wildlife and environment. Most available literature to date has focused on faecal samples from Antarctic vertebrates. Therefore, this study addressed the possible presence of parasites in Antarctic soil that may be infectious to humans. Soil samples were obtained from five locations on Signy Island (South Orkney Islands, maritime Antarctic), namely North Point and Gourlay Peninsula (penguin rookeries), Pumphouse (relic coal-powered pump house), Jane Col (barren high altitude fellfield) and Berntsen Point (low altitude vegetated fellfield close to current research station). Approximately 10% of the soil samples (14/135) from 3 out of the 5 study sites had parasites which included Diphyllobotridae spp. eggs, Cryptosporidium sp., an apicomplexan protozoa (gregarine), Toxoplasma gondii, helminths (a cestode, Tetrabothrius sp., and a nematode larva) and mites. The presence of parasites in the 3 sites are most likely due to the presence of animal and human activities as two of these sites are penguin rookeries (North Point and Gourlay Peninsula) while the third site (Pumphouse Lake) has human activity. While some of the parasite species found in the soil samples appear to be distinctive, there were also parasites such as Cryptosporidium and Toxoplasma gondii that have a global distribution and are potentially pathogenic.
    Matched MeSH terms: Toxoplasma
  17. Fulltext Recent advances in Toxoplasma gondii immunotherapeutics
    Lim SS, Othman RY
    Korean J Parasitol, 2014 Dec;52(6):581-93.
    PMID: 25548409 DOI: 10.3347/kjp.2014.52.6.581
    Toxoplasmosis is an opportunistic infection caused by the protozoan parasite Toxoplasma gondii. T. gondii is widespread globally and causes severe diseases in individuals with impaired immune defences as well as congenitally infected infants. The high prevalence rate in some parts of the world such as South America and Africa, coupled with the current drug treatments that trigger hypersensitivity reactions, makes the development of immunotherapeutics intervention a highly important research priority. Immunotherapeutics strategies could either be a vaccine which would confer a pre-emptive immunity to infection, or passive immunization in cases of disease recrudescence or recurrent clinical diseases. As the severity of clinical manifestations is often greater in developing nations, the development of well-tolerated and safe immunotherapeutics becomes not only a scientific pursuit, but a humanitarian enterprise. In the last few years, much progress has been made in vaccine research with new antigens, novel adjuvants, and innovative vaccine delivery such as nanoparticles and antigen encapsulations. A literature search over the past 5 years showed that most experimental studies were focused on DNA vaccination at 52%, followed by protein vaccination which formed 36% of the studies, live attenuated vaccinations at 9%, and heterologous vaccination at 3%; while there were few on passive immunization. Recent progress in studies on vaccination, passive immunization, as well as insights gained from these immunotherapeutics is highlighted in this review.
    Matched MeSH terms: Toxoplasma/immunology*
  18. Optimization for high-level expression in Pichia pastoris and purification of truncated and full length recombinant SAG2 of Toxoplasma gondii for diagnostic use
    Ling LY, Ithoi I, Yik FM
    Southeast Asian J. Trop. Med. Public Health, 2010 May;41(3):507-13.
    PMID: 20578535
    SAG2 is one of the major surface antigens of the intracellular protozoan parasite Toxoplasma gondii. In the present study, truncated recombinant SAG2(S) and full length recombinant SAG2(T) of T. gondii were optimally produced (approximately 15 mg/liter) in Pichia pastoris expression system using BMMY medium at pH 3, 25 degrees C in 0.5-1% methanol and a time-course of 1-2 days. The recombinant proteins were purified using a commercial gel filtration purification system obtaining approximately 33% recovery. The purified SAG2(S) and SAG2(T) showed molecular masses of 45 and 36 kDa by SDS-PAGE, respectively. The recombinant proteins were evaluated by Western blotting with patients' sera and demonstrated 90% sensitivity and 100% specificity for detection of toxoplasmosis. This study provided a means for large-scale expression and purification of SAG2, which should be useful for diagnosis of toxoplasmosis.
    Matched MeSH terms: Toxoplasma/isolation & purification*
  19. Vaccination challenges and strategies against long-lived Toxoplasma gondii
    Loh FK, Nathan S, Chow SC, Fang CM
    Vaccine, 2019 07 09;37(30):3989-4000.
    PMID: 31186188 DOI: 10.1016/j.vaccine.2019.05.083
    Since the discovery of Toxoplasma gondii in 1908, it is estimated that one-third of the global population has been exposed to this ubiquitous intracellular protozoan. The complex life cycle of T. gondii has enabled itself to overcome stress and transmit easily within a broad host range thus achieving a high seroprevalence worldwide. To date, toxoplasmosis remains one of the most prevalent HIV-associated opportunistic central nervous system infections. This review presents a comprehensive overview of different vaccination approaches ranging from traditional inactivated whole-T. gondii vaccines to the popular DNA vaccines. Extensive discussions are made to highlight the challenges in constructing these vaccines, selecting adjuvants as well as delivery methods, immunisation approaches and developing study models. Herein we also deliberate over the latest and promising enhancement strategies that can address the limitations in developing an effective T. gondii prophylactic vaccine.
    Matched MeSH terms: Toxoplasma/immunology*; Toxoplasma/pathogenicity*
  20. Fulltext A community-based survey of Toxoplasma gondii infection among pregnant women in rural areas of Taiz governorate, Yemen: the risk of waterborne transmission
    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
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