• Parasites, Hosts and Diseases
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• v.52 no.4
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• pp.367-376
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• 2014

Recombinant antigenic proteins of Toxoplasma gondii are alternative source of antigens which are easily obtainable for serodiagnosis of toxoplasmosis. In this study, highly antigenic secretory organellar proteins, dense granular GRA2 and GRA3, rhoptrial ROP2, and micronemal MIC2, were analyzed by bioinformatics approach to express as water-soluble forms of antigenic domains. The transmembrane region and disorder tendency of 4 secretory proteins were predicted to clone the genes into pGEX-4T-1 vector. Recombinant plasmids were transformed into BL21 (DE3) pLysS E. coli, and GST fusion proteins were expressed with IPTG. As a result, GST fusion proteins with $GRA2_{25-105}$, $GRA3_{39-138}$, $ROP2_{324-561}$, and $MIC2_{1-284}$ domains had respectively higher value of IgG avidity. The $rGST-GRA2_{25-105}$ and $rGST-GRA3_{39-138}$ were soluble, while $rGST-ROP2_{324-561}$ and $rGST-MIC2_{1-284}$ were not. $GRA2_{31-71}$, intrinsically unstructured domain (IUD) of GRA2, was used as a linker to enhance the solubility. The $rGST-GRA2_{31-71}-ROP2_{324-561}$, a chimeric protein, appeared to be soluble. Moreover, $rGST-GRA2_{31-71}-MIC2_{1-284}$ was also soluble and had higher IgG avidity comparing to $rGST-MIC2_{1-284}$. These 4 highly expressed and water-soluble recombinant antigenic proteins may be promising candidates to improve the serodiagnosis of toxoplasmosis in addition to the major surface antigen of SAG1.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1026-1031
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• 2006

The optimization of the production of a fusion protein containing the antigenic domain 1 (AD-1) is of a great importance, considering its use in diagnostic tests. The fusion protein is produced by the fermentation of a recombinant strain of Escherichia coli containing the plasmid Mbg58, which expresses the AD-1 (aa 484-650) of human cytomegalovirus glycoprotein B as a fusion protein together with aa 1-375 of ${\beta}-galactosidase$. An important characteristic of promoters (lac and derivatives) used in recombinant protein production in E. coli is their inducibility. Induction by IPTG is widely used for basic research; however, its use in large-scale production is undesirable because of its high cost and toxicity. In this work, studies using different inducers and carbon sources for the production of a fusion protein containing the AD-l were performed. The results showed that lactose could be used as an inducer in the fermentation process for the production of this protein, and that expression levels could exceed those achieved with IPTG. The use of lactose for protein expression in E. coli should be extremely useful for the inexpensive, large-scale production of heterologous proteins in E. coli. Addition of sucrose to the fermentation medium improved the yield of recombinant protein, whereas addition of fructose or trehalose decreased the yield.

• Parasites, Hosts and Diseases
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• v.39 no.3
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• pp.241-246
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• 2001

The antigenic domain of the major surface protein (Nc-p43) of Neospora caninum was examined by polymerase chain reaction of its gene fragments and recombinant expression as GST fusion proteins. The fragments of Nc-p43 were as follow: a total open reading frame (OFR), T: OFR without signal sequence and C-terminal hydrophobic sequence, S: N-terminal 2/3 parts of S, A: C-terminal 2/3 parts, P; N-terminal 1/3 part, X: middle 1/3 part Y; and C-terminal 1/3 part, Z, respectively. The DNA fragments were cloned into pGEX-47 vector. Recombinant plasmids transformed into Escherichia coli of BL21 pLysS (DE3) strain were induced to express GST or GST fused fragments of Nc-p43 such as 69 kDa protein for T,66 kDa for S, 52 kDa for A,53 kDa for P, and 40 kDa proteins for X, Y, and Z, respectively in SDS-PAGE. The Nc-p43 fragments of T, S, and P reacted with a bovine serum of neosporosis while those of A, X, Y, and Z together with GST did not in the western blot. These findings suggest that the antigenic domain of Nc-p43 of N. caninum may be localized in the C-terminal 2/3 parts. Together with Al9 clone in SAGI of Toxoplasma gondii (Nam et at., 1996), the P fragment of Nc-p43 could be used as efficient antigens to diagnose and differentiate those infections with both species .

• Parasites, Hosts and Diseases
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• v.51 no.5
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• pp.503-510
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• 2013

Toxoplasma gondii is an apicomplexan parasite with a broad host range of most warm-blooded mammals including humans, of which one-thirds of the human population has been infected worldwide which can cause congenital defects, abortion, and neonatal complications. Here, we developed a rapid diagnostic test (RDT) for T. gondii infection. Antigenic N-terminal half of the major surface antigen (SAG1) was linked with intrinsically unstructured domain (IUD) of dense granule protein 2 (GRA2). The recombinant GST-GRA2-SAG1A protein was successfully expressed and purified as 51 kDa of molecular weight. Furthermore, antigenicity and solubility of the rGST-GRA2-SAG1A protein were significantly increased. The overall specificity and sensitivity of GST-GRA2-SAG1A loaded RDT (TgRDT) were estimated as 100% and 97.1% by comparing with ELISA result which uses T. gondii whole cell lysates as the antigen. The TgRDT tested with Uganda people sera for field trial and showed 31.9% of seroprevalence against T. gondii antibody. The TgRDT is proved to be a kit for rapid and easy to use with high accuracy, which would be a suitable serodiagnostic tool for toxoplasmosis.

• Parasites, Hosts and Diseases
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• v.34 no.2
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• pp.135-142
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• 1996

Antigenic domain of jai or surface protein (p30) of Toxoplosmc Sondii was analyzed after polymerase chain reaction (PCR) of its gene fragments. Hydrophilic or hydrophobic moiety of amino acid sequences were expressed as glutathione S-transferase (G57) fusion proteins. Fragments of p30 gene were as follows: 737, total p30 open reading frame (ORF) ; S28, total ORF excluding N-terminal signal sequence and C-terminal hydrophobic sequence; Al9, N-terminal 2/3 parts of A28; A19, N-terminal 2/3 of S28; P9, C-terminal 2/3 part of S28; Z9. middle 1/3 of S28; and 29, C-terminal 1/3 of S28. respectively. Primer of each fragment was synthesized to include clamp sequence of EcoR I restriction site. PCR amplified DNA was inserted info GST (26 kDa) expression vector, PGEX-47-1 to transform into Escheri,hia coei (.JM105 strain). G57 fusion proteins were expressed with IPTG induction as 63. 54, 45, 45, 35, 36. and 35 kDa proteins measured by SDS-PAGE. Each fusion protein was confirmed with G57 detection kit. Western blot analysis with the serum of a toxoplasmosis patient revealed antigenicity in proteins expressed by T37. S28, and Al9 but not those by Pl8. X9, Y10, and Z9. Antigenicity of p30 seems to be located either in N-terminal 115 part in the presence of middle 1/3 part or in the oligopeptides between margins of the first and second 1/3 parts.

• BMB Reports
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• v.40 no.6
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• pp.1002-1008
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• 2007

PreS domain of Hepatitis B virus (HBV) surface antigen is a good candidate for an effective vaccine as it activates both B and T cells besides binding to hepatocytes. This report deals with overexpression and purification of adr subtype of surface antigen that is more prevalent in Pakistan. PreS region, comprising 119 aa preS1 region plus a 55 aa preS2 region plus 11 aa from the N-terminal S region, was inserted in pET21a+ vector, cloned in E. coli $DH5\alpha$ cells and expressed in E. coli BL21 codon+ cells. The conditions for over expression were optimized using different concentrations of IPTG (0.01-5 mM), and incubating the cells at different temperatures (23-$41^{\circ}C$) for different durations (0-6 h). The cells were grown under the given optimized conditions (0.5 mM IPTG concentration at $37^{\circ}C$ for 4 h), lysed by sonication and the protein was purified by ion exchange chromatography. On the average, 24.5 mg of recombinant protein was purified per liter of culture. The purified protein was later lyophilized and stored at $-80^{\circ}C$.

• Animal cells and systems
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• v.3 no.2
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• pp.221-228
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• 1999

In order to find a biochemical marker for late Iysosomes, we characterized two cDNAs which were cloned by using a monoclonal antibody (mAb) against Iysosomes in Amoeba proteus as a probe. The two cDNAs, a 1.3-kb cDNA in pBSK-Iys45 and a 1.6-kb cDNA in pBSK-Iys60, were found to encode proteins homologous to pepstatin-insensitive carboxyl proteinases (PICPs). E. coli transformed with pBSK-Iys45 produced two immunopositive polypeptides (45 and 43 kDa) and the cDNA in 1274 bases encoded a 44,733-Da protein (Lys45) of 420 amino acids containing one site for a core oligosaccharide. On the other hand, E. coli transformed with pBSK-Iys60 produced several polypeptides (64, 54, 45, 41, and 37 kDa) reacting with the mAb. The cDNA contained 1629 bases and encoded a 59,231-Da protein (Lys60) of 530 amino acids containing two sites for asparagine-linked core oligosaccharides. These two cDNAs showed identities of 60.3% in nucleotide sequences and 23.6% in amino acid sequences. Lys45 and Lys60 appeared to share XXEFQK as a common antigenic domain. The amino acid sequence of the Lys45 protein showed 17.4% identity and 40.9% similarity to that of PICP from Pseudomonas sp. 101. On the other hand, Lys60 showed a 24.3% identity and 51.9% similarity with human Iysosomal PICP in the amino acid sequence. A putative active center for serine protease, GTS＊xxxxxFxG, was found to be conserved among PICP homologues. The two PICPs are the first reported enzymatic markers for late Iysosomes.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.126-134
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• 2022

Norovirus (NoV) is an important pathogen causing acute gastroenteritis worldwide. The purpose of the present study was the molecular characterization of NoV. A total of 408 stool specimens collected from hospitalized children associated with acute gastroenteritis in Chiang Rai, Thailand, 2015-2017 were investigated for the presence of NoVs by RT-PCR. NoV GII was detected in 32 samples (7.8%). Five distinct genotypes were identified, including GII.4 (13/32, 40.6%), GII.3 (11/32, 34.3%), GII.17 (4/32, 12.5%), GII.2 (2/32, 6.3%), and GII.14 (2/32, 6.3%). NoV infection occurred mostly in young children under 3 years of age (31/32, 96.9%) and showed the main peak in summer months from March to April (18/32, 56.3%). Phylogenetic analysis revealed that all 13 GII.4 strains clustered with GII.4 Sydney 2012 variant. Representative GII.3 strains were analyzed as a recombinant GII.3P[12] strain. Several amino acid differences were found in the antigenic epitopes and antibody binding sites of the VP1 capsid of the GII.3P[12]. Homology modeling of the P domain of the GII.3P[12] strain demonstrated that 10/13 amino acid differences were predicted to be located on the surface-exposed area of the capsid structure. These amino acid changes might affect the infectivity and the antigenicity of the recombinant GII.3P[12]. The prevalence of GII.4 Sydney 2012 and recombinant GII.3P[12] strains indicates the genetic diversity of circulating NoVs in Thailand, emphazing the importance of continuous surveillance to mornitor newly emerging NoV strains in the future.

• Korean Journal of Veterinary Service
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• v.25 no.3
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• pp.245-257
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• 2002

The gene encoding the HN protein from the CBP-1 strain, a heat stable Newcastle disease virus (NDV) isolated from diseased pheasants in Korea, was characterized by reverse transcriptase- polymerase chain reaction(RT-PCR) and the nucleotide and amino acid sequences were analyzed following cloning of the HN gene. In all of the NDV strains studied, a 1.75 kb size cDNA fragment for the HN gene was generated by RT-PCR and smaller specific band sizes harboring the internal portions of the HN gene were also detected by using four pairs of primers. The RT-PCR was sensitive enough to detect viral transcripts when the virus titer was above 25 hemagglutination units. The amplified 1.75 kb cDNA was cloned into a BamHI site of the pVL1393 Baculo transfer vector. The nucleotide sequences of the 1,758 bp HN gene from the CBP-1 strain were determined by the dye terminator cyclic sequencing method. The gene sequences were compared among the strains of CBP-1, Texas GB, Beaudette C, LaSota, B1 and Ulster. The homology of the CBP-1 HN gene to other HN variants was 97.8% to Texas GB, 98.4% to Beaudette C, 95.4% to LaSota, 95.6% to B1 and 90.2% to Ulster. As the deduced 577 amino acid sequences were compared among the strains, the homology for CBP-1 HN appeared to be 96.7% to Texas GB, 97.9% to Beaudette C, 95.5% to LaSota, 95.5% to B1 and 92.7% to Ulster. It was evident that the amino acid sequences included 5 sites for N-asparagine linked glycosylation and 12 cysteine residues. The three conserved leucine residues within the predicted transmembrane domain of the HN protein are amino acid 30, 37 and 44. The three antigenic sites on the HN protein of NDV are amino acids 347(Glu), 481(Asn) and 495(Glu). These data indicate that the genotype of the CBP-1 strain is more closely associated with the strains of Texas GB and Beaudette C than it is for the LaSota, B1 and Ulster strains.

• Parasites, Hosts and Diseases
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• v.53 no.4
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• pp.403-411
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• 2015

Plasmodium falciparum can invade all stages of red blood cells, while Plasmodium vivax can invade only reticulocytes. Although many P. vivax proteins have been discovered, their functions are largely unknown. Among them, P. vivax reticulocyte binding proteins (PvRBP1 and PvRBP2) recognize and bind to reticulocytes. Both proteins possess a C-terminal hydrophobic transmembrane domain, which drives adhesion to reticulocytes. PvRBP1 and PvRBP2 are large (>326 kDa), which hinders identification of the functional domains. In this study, the complete genome information of the P. vivax RBP family was thoroughly analyzed using a prediction server with bioinformatics data to predict B-cell epitope domains. Eleven pvrbp family genes that included 2 pseudogenes and 9 full or partial length genes were selected and used to express recombinant proteins in a wheat germ cell-free system. The expressed proteins were used to evaluate the humoral immune response with vivax malaria patients and healthy individual serum samples by protein microarray. The recombinant fragments of 9 PvRBP proteins were successfully expressed; the soluble proteins ranged in molecular weight from 16 to 34 kDa. Evaluation of the humoral immune response to each recombinant PvRBP protein indicated a high antigenicity, with 38-88% sensitivity and 100% specificity. Of them, N-terminal parts of PvRBP2c (PVX_090325-1) and PvRBP2 like partial A (PVX_090330-1) elicited high antigenicity. In addition, the PvRBP2-like homologue B (PVX_116930) fragment was newly identified as high antigenicity and may be exploited as a potential antigenic candidate among the PvRBP family. The functional activity of the PvRBP family on merozoite invasion remains unknown.