Displaying publications 1 - 20 of 176 in total

  1. Ching XT, Lau YL, Fong MY, Nissapatorn V, Andiappan H
    Biomed Res Int, 2014;2014:690529.
    PMID: 24987700 DOI: 10.1155/2014/690529
    Toxoplasma gondii infects all warm-blooded animals, including humans, causing serious public health problems and great economic loss for the food industry. Commonly used serological tests require costly and hazardous preparation of whole Toxoplasma lysate antigens from tachyzoites. Here, we have evaluated an alternative method for antigen production, which involved a prokaryotic expression system. Specifically, we expressed T. gondii dense granular protein-5 (GRA5) in Escherichia coli and isolated it by affinity purification. The serodiagnostic potential of the purified recombinant GRA5 (rGRA5) was tested through Western blot analysis against 212 human patient serum samples. We found that rGRA5 protein was 100% specific for analysis of toxoplasmosis-negative human sera. Also, rGRA5 was able to detect acute and chronic T. gondii infections (sensitivities of 46.8% and 61.2%, resp.).
    Matched MeSH terms: Blotting, Western/methods*
  2. Saadatnia G, Ghaffarifar F, Khalilpour A, Amerizadeh A, Rahmah N
    Trop Biomed, 2011 Dec;28(3):606-14.
    PMID: 22433890 MyJurnal
    Toxoplasmosis can cause serious disease in immunocompromised patients and to congenitally infected foetuses. Appropriate laboratory investigations in potential cases of acute Toxoplasma infection are important. Excretory secretory antigen (ESA) is immunogenic during both human and experimental infections, therefore is considered as a good candidate for investigation into new infection markers. In this study, ESA was prepared from in vitro cultures of Toxoplasma gondii to identify T. gondii ESA antigenic component(s) that is/are most reactive with serum samples from probable acute cases of toxoplasmosis. Serum samples were obtained from several categories of individuals with the following Toxoplasma serology: Group I: IgM+ IgG+ (low IgG avidity) or IgM+ IgG- from sera of patients who had clinical query of toxoplasmosis (n=35). Group II: IgM- IgG+ (high IgG avidity) from chronically infected individuals (n=30). Group III: normal/healthy individuals with anti-Toxoplasma IgMIgG- (n=20). Group IV: individuals with other infections who had anti-Toxoplasma IgM- IgG- (n=10). The ESA was subjected to SDS-PAGE, followed by Western blot analysis using the above sera and probed with peroxidase conjugated anti-human IgM and IgA antibodies. The blots were then developed using chemiluminescence substrate. The selected antigenic band was excised from the gel after two dimensional electrophoresis and sent for mass spectrometry analysis using MALDI TOF-TOF. The most promising antigenic band was a 10 kDa protein which showed sensitivity of 80% in both IgM and IgA blots, and specificity of 96.7% with sera from other infections and healthy controls. The two best identifications for the 10 kDa band were ubiquitin (ribosomal protein CEP52 fusion protein) and polyubiquitin.
    Matched MeSH terms: Blotting, Western/methods
  3. 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: Blotting, Western/methods
  4. Tengku-Idris TIN, Fong MY, Lau YL
    Trop. Med. Int. Health, 2018 12;23(12):1374-1383.
    PMID: 30286271 DOI: 10.1111/tmi.13160
    OBJECTIVE: To investigate the seroprevalence of Sarcocystosis in the local communities of Pangkor and Tioman islands, Malaysia, by using antigenic recombinant surface antigens 2 and 3 from Sarcocystis falcatula (rSfSAG2 and rSfSAG3) as the target proteins via Western blot and ELISA assays.

    METHODS: SfSAG2 and SfSAG3 genes were isolated from S. falcatula and expressed in Escherichia coli expression system. A total of 348 serum samples [volunteers from both islands (n = 100), non-Sarcocystis parasitic infections patients (n = 50) and healthy donors (n = 100)] were collected and tested with purified SfSAGs in Western blot and ELISA assays to measure the seroprevalence of human sarcocystosis.

    RESULTS: None of the sera in this study reacted with rSfSAG2 by Western blot and ELISA. For rSfSAG3, relatively high prevalence of sarcocystosis was observed in Tioman Island (75.5%) than in Pangkor Island (34%) by Western blot. In ELISA, the different prevalence rate was observed between Tioman Island (43.8%) and Pangkor Island (37%). The prevalence rate in other parasitic infections (amoebiasis, cysticercosis, filariasis, malaria, toxocariasis and toxoplasmosis) was 30% by Western blot and 26% by ELISA. Only 8% (by Western blot) and 10% (by ELISA) of healthy donors showed reactivity towards rSfSAG3.

    CONCLUSION: This is the first study reporting a seroprevalence of sarcocystosis in Pangkor and Tioman Islands, Malaysia. The combination of Western blot and ELISA is suitable to be used for serodiagnosis of sarcocystosis. With further evaluations, SfSAG3 can potentially be used to confirm infection, asymptomatic screening, surveillance and epidemiological studies.

    Matched MeSH terms: Blotting, Western/methods
  5. Emelia O, Zeehaida M, Sulaiman O, Rohela M, Saadatnia G, Yeng C, et al.
    J Immunoassay Immunochem, 2010;31(1):79-91.
    PMID: 20391020 DOI: 10.1080/15321810903405134
    We have developed an ELISA that employs monoclonal anti-Toxoplasma SAG1 (p30) as the capture antibody to detect T. gondii circulating antigens in patients' serum samples. Using serum spiked with Toxoplasma soluble and with SAG1 recombinant proteins, the detection limits were 31.25 ng/mL and 62.50 ng/mL, respectively. We obtained positive results in 28% (21/75) and 11% (23/206) of probable active and chronic toxoplasmosis serum samples, respectively. Western blot analysis on pooled antigen-positive serum samples showed antigenic bands of molecular weights 25 and 75 kDa from sera of probable active infection and five antigenic bands ranging in size from 26 to 33 kDa from chronic infection sera. This assay would be useful as an initial serum selection step in developing a Toxoplasma antigen detection test and for characterization studies.
    Matched MeSH terms: Blotting, Western
  6. Somarny WM, Mariana NS, Rozita R, Raha AR
    PMID: 15916081
    The cholera enterotoxin (CT) has been considered a major virulence factor of Vibrio cholerae. The accessory cholera enterotoxin (ace) gene is the third gene of V. cholerae virulence cassette. The gene coding for the Ace toxin was amplified from V. cholerae isolates producing a single band of 314 bp. The presence of ace gene was confirmed by hybridization as well as by sequencing. The gene was successfully expressed in Escherichia coli (LMG194) using expression, pBAD/Thio-TOPO vector. Optimal conditions for expression included choice of host strain, temperature used for culturing, and concentration of antibiotic and arabinose inducer. The Ace protein was obtained from the cell supernatant as a fusion protein with a molecular mass 34 kDa which was detected using an anti V5-HRP epitope tagged antibody.
    Matched MeSH terms: Blotting, Western
  7. Gam LH, Latiff A
    Int. J. Biol. Sci., 2005;1(3):103-9.
    PMID: 16094462
    The microheterogeneity property of hCG with regards to its sialic acid contents resulted in variable mobility of the glycoprotein in SDS-PAGE. The intact hCG molecule is composed of two dissimilar subunits, namely alpha- and beta-subunits. The identification of hCG bands in SDS-PAGE was accomplished by the immunoblotting experiment, whereby the antibody directed toward the specific region of beta-subunit of hCG was used. The data shows that the different mobility of intact hCG was attributed to the different degree of desialylation of the glycoprotein. Nevertheless, unlike the intact hCG, the mobility of its beta-subunit was not affected by its variety sialic acid content. This characteristic of beta-hCG is beneficial when semi-quantification of total hCG is required. Quantification of hCG using the HPLC-reversed phase C18 analytical column is not possible as the glycoprotein was eluted in multiple fractions at different retention times. The identification of denatured hCG (HPLC eluted fractions) was carried out by immunoblotting experiment whilst immunoassay technique failed to detect its presence in any fraction.
    Matched MeSH terms: Blotting, Western
  8. Yuen HL, Shamala D, Thong KL
    J Infect Dev Ctries, 2008;2(4):313-23.
    PMID: 19741295
    BACKGROUND: Heat shock proteins (HSPs) are known to be involved in the pathogenesis of Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever. The objective of this study was to apply a phage display library to identify mimotopes of two HSPs, HSP90 and DnaK in S. Typhi.
    METHODOLOGY: A 12-mer random peptide library expressed on the surface of the filamentous phage, M13, was used to select the mimotopes of two S. Typhi heat shock proteins by biopanning with monoclonal antibodies (mAbs), DnaK and HSP90. The immunogenicity of the selected peptides was determined through binding affinity with polyclonal antibodies from pooled typhoid-confirmed patients' sera and purified HSPs mAb using Western blotting and ELISA.
    RESULTS: Five rounds of biopanning resulted in enrichment of phage clones expressing the binding motifs TDxSTRP and FPSHYWLYPPPT, respectively. The selected peptides showed strong immunoreactivity with patients' sera. Thus, monoclonal antibodies against HSP and patient sera can select common mimotopes from the random peptide library.
    CONCLUSION: These findings may provide fundamental information for further studies on diagnostic application or vaccine design against this aetiologic agent of typhoid fever.
    Matched MeSH terms: Blotting, Western
  9. Morvarid, A.R., Zeenathul, N.A., Tam, Y.J., Zuridah, H., Mohd-Azmi, M.L., Azizon, B.O.
    This study describes expression of HBs Ag in methylotrophic yeast, Pichia Pastoris under alcohol oxidase promoter. A single copy number of HBs Ag gene was transformed into pichia strain of KM 71, a Muts type, by using pA0815 pichia expression vector. The recombinant was cultivated in a shake flask either using methanol or a mixed feed of glycerol -methanol for induction. The HBs Ag gene integrity was justified using direct PCR method. The expressed products in the soluble cell extracts were analyzed by Western blot, SDS page, Bradford assay and ELISA tests. The recombinant HBs Ag was expressed successfully in Pichia pastoris strain KM71 at a high level of HBs Ag protein expression. Thus, an addition of glycerol in the ratio of glycerol per methanol 1/1 (g g-1) consistently produced 2-fold increment in both biomass accumulation and HBs Ag productivity.
    Matched MeSH terms: Blotting, Western
  10. Arifin N, Yunus MH, Nolan TJ, Lok JB, Noordin R
    Am. J. Trop. Med. Hyg., 2018 Apr;98(4):1165-1170.
    PMID: 29436335 DOI: 10.4269/ajtmh.17-0697
    Strongyloides stercoralis is a human parasite that can cause a long-term infection. In immunosuppressed patients, strongyloidiasis may be fatal when there is overwhelming autoinfection resulting in the migration of large numbers of larvae through many organs. Definitive diagnosis is still a challenge, and a combination of symptoms, microscopic identification, and serology test results are often used to arrive at a clinical decision. However, intermittent larval excretion, low parasite burden, and occult infections are challenges with parasitological diagnosis of infection with S. stercoralis. Meanwhile, serologic tests using immunoglobulin G and parasite antigen extract have problems of cross-reactivity with other helminthic infections. Recombinant antigen-based serodiagnosis is a good alternative to overcome the laboratory diagnostic issues. Herein, we report on the isolation of cDNA clone encoding an antigen of potential diagnostic value identified from immunoscreening of a S. stercoralis cDNA library. The translated protein had highest similarity to Strongyloides ratti immunoglobulin-binding protein 1. The recombinant antigen produced, rSs1a, was assessed using western blot and enzyme-linked immunosorbent assay. The latter showed 96% diagnostic sensitivity and 93% specificity; thus, rSs1a has good potential for use in serodiagnosis of human strongyloidiasis.
    Matched MeSH terms: Blotting, Western
  11. Sum, Magdline Sia Henry, Andrew, Anna, Maling, Milda Aren
    Chikungunya is an acute febrile illness caused by chikungunya virus (CHIKV). In this study, the envelope E1 gene of CHIKV was cloned and expressed in a baculovirus system. The recombinant E1 protein with N-term 6-His residues protein was successfully expressed and purified as confirmed by SDS-PAGE and western blot analysis. The seroreactivity of the recombinant protein was evaluated in immunoassay for anti-CHIKV IgM and IgG antibodies. The recombinant antigen showed 69% sensitivity and 100% specificity for anti-CHIKV IgG by dot blot assay. Detection of anti-CHIKV IgM by dot assay showed 79% sensitivity and 100% specificity. No cross reactivity of the antigen was observed with anti-dengue virus serum samples. The results strongly support that the recombinant E1 protein has potential to be used as diagnostic antigen. The used of the antigen in a dot blot assay gives an advantage for laboratory detection without the need of any specialised equipment.
    Matched MeSH terms: Blotting, Western
  12. Lee HC, Md Yusof HH, Leong MP, Zainal Abidin S, Seth EA, Hewitt CA, et al.
    Int. J. Neurosci., 2019 Feb 18.
    PMID: 30775947 DOI: 10.1080/00207454.2019.1580280
    AIMS: The JAK-STAT signalling pathway is one of the key regulators of pro-gliogenesis process during brain development. Down syndrome (DS) individuals, as well as DS mouse models, exhibit an increased number of astrocytes, suggesting an imbalance of neurogenic-to-gliogenic shift attributed to dysregulated JAK-STAT signalling pathway. The gene and protein expression profiles of JAK-STAT pathway members have not been characterised in the DS models. Therefore, we aimed to profile the expression of Jak1, Jak2, Stat1, Stat3 and Stat6 at different stages of brain development in the Ts1Cje mouse model of DS.

    METHODS: Whole brain samples from Ts1Cje and wild-type mice at embryonic day (E)10.5, E15, postnatal day (P)1.5; and embryonic cortex-derived neurospheres were collected for gene and protein expression analysis. Gene expression profiles of three brain regions (cerebral cortex, cerebellum and hippocampus) from Ts1Cje and wild-type mice across four time-points (P1.5, P15, P30 and P84) were also analysed.

    RESULTS: In the developing mouse brain, none of the Jak/Stat genes were differentially expressed in the Ts1Cje model compared to wild-type mice. However, Western blot analyses indicated that phosphorylated (p)-Jak2, p-Stat3 and p-Stat6 were downregulated in the Ts1Cje model. During the postnatal brain development, Jak/Stat genes showed complex expression patterns, as most of the members were downregulated at different selected time-points. Notably, embryonic cortex-derived neurospheres from Ts1Cje mouse brain expressed lower Stat3 and Stat6 protein compared to the wild-type group.

    CONCLUSION: The comprehensive expression profiling of Jak/Stat candidates provides insights on the potential role of the JAK-STAT signalling pathway during abnormal development of the Ts1Cje mouse brains.

    Matched MeSH terms: Blotting, Western
  13. Khanam R, Hejazi II, Shahabuddin S, Bhat AR, Athar F
    J Pharm Anal, 2019 Apr;9(2):133-141.
    PMID: 31011470 DOI: 10.1016/j.jpha.2018.12.002
    1, 3, 4-Oxadiazole derivatives (4a-5f) were previously synthesized to investigate their anticancer properties. However, studies relating to their antioxidant potential and signal transducer and activator of transcription (STAT) inhibition have not been performed. We investigated previously synthesized 1, 3, 4-oxadiazole derivatives (4a-5f) for various radical scavenging properties using several in vitro antioxidant assays and also for direct inhibition of STAT3 through molecular docking. The data obtained from various antioxidant assays such as 2, 2,-diphenyl-1-picrylhydrazyl radical (DPPH), nitric oxide, hydrogen peroxide, and superoxide anion radical revealed that among all the derivatives, compound 5e displayed high antioxidant activities than the standard antioxidant L-ascorbic acid. Additionally, the total reduction assay and antioxidant capacity assay further confirmed the antioxidant potential of compound 5e. Furthermore, the molecular docking studies performed for all derivatives along with the standard inhibitor STX-0119 showed that binding energy released in direct binding with the SH2 domain of STAT3 was the highest for compound 5e (-9.91kcal/mol). Through virtual screening, compound 5e was found to exhibit optimum competency in inhibiting STAT3 activity. Compound 5e decreased the activation of STAT3 as observed with Western blot. In brief, compound 5e was identified as a potent antioxidant agent and STAT3 inhibitor and effective agent for cancer treatment.
    Matched MeSH terms: Blotting, Western
  14. Sonaimuthu P, Cheong FW, Chin LC, Mahmud R, Fong MY, Lau YL
    Exp. Parasitol., 2015 Jun;153:118-22.
    PMID: 25812552 DOI: 10.1016/j.exppara.2015.03.010
    Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Human infection with Plasmodium knowlesi is widely distributed in Southeast Asia. Merozoite surface protein-1₁₉ (MSP-1₁₉), which plays an important role in protective immunity against asexual blood stage malaria parasites, appears as a leading immunogenic antigen of Plasmodium sp. We evaluated the sensitivity and specificity of recombinant P. knowlesi MSP-1₁₉ (rMSP-1₁₉) for detection of malarial infection. rMSP-1₁₉ was expressed in Escherichia coli expression system and the purified rMSP-1₁₉ was evaluated with malaria, non-malaria and healthy human serum samples (n = 215) in immunoblots. The sensitivity of rMSP-1₁₉ for detection of P. knowlesi, Plasmodium falciparum, Plasmodium  vivax and Plasmodium  ovale infection was 95.5%, 75.0%, 85.7% and 100%, respectively. rMSP-1₁₉ did not react with all the non-malaria and healthy donor sera, which represents 100% specificity. The rMSP-1₁₉ could be used as a potential antigen in serodiagnosis of malarial infection in humans.
    Matched MeSH terms: Blotting, Western/methods*
  15. 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: Blotting, Western*
  16. Ching XT, Lau YL, Fong MY, Nissapatorn V
    Parasitol. Res., 2013 Mar;112(3):1229-36.
    PMID: 23274488 DOI: 10.1007/s00436-012-3255-5
    Toxoplasma gondii infects all warm-blooded animals including humans, causing serious public health problems and great economic loss in the food industry. Commonly used serological tests involve preparation of whole Toxoplasma lysate antigens from tachyzoites which are costly and hazardous. An alternative method for better antigen production involving the prokaryotic expression system was therefore used in this study. Recombinant dense granular protein, GRA2, was successfully cloned, expressed, and purified in Escherichia coli, BL21 (DE3) pLysS. The potential of this purified antigen for diagnosis of human infections was evaluated through western blot analysis against 100 human serum samples. Results showed that the rGRA2 protein has 100 and 61.5 % sensitivity towards acute and chronic infection, respectively, in T. gondii-infected humans, indicating that this protein is useful in differentiating present and past infections. Therefore, it is suitable to be used as a sensitive and specific molecular marker for the serodiagnosis of Toxoplasma infection in both humans and animals.
    Matched MeSH terms: Blotting, Western/methods*
  17. Liu W, Wang YT, Tian DS, Yin ZC, Kwang J
    Dis. Aquat. Org., 2002 Apr 24;49(1):11-8.
    PMID: 12093036
    The vp28 gene encoding an envelope protein (28 kDa) of white spot syndrome virus (WSSV) was amplified from WSSV-infected tiger shrimp that originated from Malaysia. Recombinant VP28 protein (r-28) was expressed in Escherichia coli and used as an antigen for preparation of monoclonal antibodies (MAbs). Three murine MAbs (6F6, 6H4 and 9C10) that were screened by r-28 antigen-based enzyme-linked immunosorbent assay (ELISA) were also able to recognize viral VP28 protein as well as r-28 on Western blot. Three non-overlapping epitopes of VP28 protein were determined using the MAbs in competitive ELISA; thus, an antigen-capture ELISA (Ac-ELISA) was developed by virtue of these MAbs. Ac-ELISA can differentiate WSSV-infected shrimp from uninfected shrimp and was further confirmed by a polymerase chain reaction (PCR) and Western blot. Approximately 400 pg of purified WSSV sample and 20 pg of r-28 could be detected by Ac-ELISA, which is comparable in sensitivity to PCR assay but more sensitive than Western blot in the detection of purified virus. Hemolymph and tissue homogenate samples collected from a shrimp farm in Malaysia during December 2000 and July 2001 were also detected by Ac-ELISA and PCR with corroborating results.
    Matched MeSH terms: Blotting, Western/methods; Blotting, Western/veterinary
  18. Gholami K, Muniandy S, Salleh N
    Res. Vet. Sci., 2014 Feb;96(1):164-70.
    PMID: 24295739 DOI: 10.1016/j.rvsc.2013.11.005
    Oestrogen-induced uterine fluid sodium (Na(+)) and bicarbonate (HCO3(-)) secretion may involve SLC4A4. We hypothesized that uterine SLC4A4 expression changes under different sex-steroid influence, therefore may account for the fluctuation in uterine fluid Na(+) and HCO3(-) content throughout the oestrous cycle. The aim of this study is to investigate the differential effects of sex-steroids and oestrous cycle phases on uterine SLC4A4 expression.
    Matched MeSH terms: Blotting, Western/veterinary
  19. Fazielawanie NM, Siraj SS, Harmin SA, Ina-Salwany MY
    Fish Physiol. Biochem., 2013 Apr;39(2):191-200.
    PMID: 22878544 DOI: 10.1007/s10695-012-9690-5
    A study was conducted to isolate, partial characterize Asian sea bass (Lates calcarifer) vitellogenin (vtg). Two-year-old juvenile L. calcarifer (n = 10) were given three intraperitoneal injections of 17-β estradiol (E2) at a dose of 2 mg/kg body weight to induce vitellogenesis. Blood was collected 3 days after the last injection, and plasma was purified through gel filtration chromatography. A broad single symmetrical peak consisting of vtg molecule was produced. Protein concentration was 0.059 mg/ml as determined by Bradfrod assay using bovine serum albumin as a standard. The protein appeared as one circulating form in Native PAGE considering the dimeric form of putative vtg with molecular weight of 545 kDa. In SDS-PAGE under reducing conditions, two major bands appeared at 232.86 and 118.80 kDa and minor bands at 100.60, 85.80 and 39.92 kDa, respectively. The purified vtg was used to generate a polyclonal antibody, and the specificity of antibody was assessed by Western blot analysis. Two major bands were immunoreacted, but no cross-reactivity was observed with plasma from non-induced males. The protein was characterized as phosphoglycolipoprotein as it positively stained for the presence of lipid, phosphorus and carbohydrate using Sudan Black B, methyl green and periodic acid/Schiff reagent solution, respectively. The amino acid composition was analyzed by high sensitivity amino acid analysis that showed high percentage of non-polar amino acids (~48 %). The results suggest the potential utilization of vtg as a basis tool to further study about reproductive physiology of this important economical species.
    Matched MeSH terms: Blotting, Western/veterinary
  20. 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: Blotting, Western/methods
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