• Journal of Life Science
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• v.20 no.12
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• pp.1743-1749
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• 2010

A research group demonstrated that the 37 kDA protein of Edwardsiella tarda, a causing causative agent of edwardsiellosis in fish, exhibited high antigenicity in Japanese flounder. The research group also showed that the N-terminus amino acid sequences of the 37 kDa protein were mapped to the N-terminus of GAPDH (glyceraldehyde-3-phosphate dehydrogenase). Using degenerated primer sets based on the known N-terminus sequence, the corresponding E. tarda DNA was amplified and cloned. The nucleotide sequences of the cloned gene revealed high homology with a bacterial gene for GAPDH, as we was expected. The amino acid sequence of E. tarda GAPDH (etGAPDH) revealed a <70% similarity with GAPDH proteins in other Enterobacteriaceae. With the application of artificial protein overexpression system in Escherichia coli, the recombinant etGAPDH (rGAPDH) was produced and purified. In this study, Using the purified rGAPDH, the etGAPDH specific polyclonal antibody has been was generated using the purified rGAPDHin this study. The immunoblotting analyses demonstrated that the location of the GAPDH protein is located with the association of is associated with the envelops of E. tarda. The rGAPDH was administrated into Japanese flounder via IP route for evaluation of the protective ability. Although the specific antibody titer against etGAPDH was increased about 3-fold after 4 weeks post-vaccination, the survival rates of vaccinated Japanese flounder and the control group with wild type E. tarda was were 12.5% and 0%, respectively. Our results indicated that rGAPDH is immunoreactive antigen but that it will not generate protective immunity in Japanese flounder.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.73-82
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• 2008

Dental caries is an infectious disease caused by mutans streptococci, and is a primary etiologic agent of dental caries in humans. The molecular pathogenesis of mutans streptococcal-associated dental caries occurs in three phases. Firstly, S. mutans attaches to tooth surface via a cell surface adhesion termed antigen I/II. In the second phase, the glucosyltransferase(GTFs) synthesize polymers like glucans in the presence of sucrose. In the third phase, the multivalent glucans interacts with glucan binding proteins (GBPs) and they make dental plaque and accumulation of microorganisms. Many studies and clinical trials have indicated that a mucosal immune response to these antigens(Ag I/II, GTFs, GBPs) of S. mutans can influence the pathogenesis of dental caries. So these antigens can be important vaccine candidates for immunologic intervention against dental caries. In this study, we cloned the genes for GTFb, GTFc, GTFd from S. mutans GS-5 and did the nucleotide sequence analysis. And the recombinant proteins of GTFd and N-terminus of GTFd were expressed. Intact GTF which we get from this experiment can be used for antibody production specific for any GTF activity domain through animal experiment.

• Parasites, Hosts and Diseases
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• v.54 no.4
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• pp.385-391
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• 2016

The discovery and understanding of antigenic proteins are essential for development of a vaccine against malaria. In Plasmodium falciparum, Pf92 have been characterized as a merozoite surface protein, and this protein is expressed at the late schizont stage, but no study of Pv92, the orthologue of Pf92 in P. vivax, has been reported. Thus, the protein structure of Pv92 was analyzed, and the gene sequence was aligned with that of other Plasmodium spp. using bioinformatics tools. The recombinant Pv92 protein was expressed and purified using bacterial expression system and used for immunization of mice to gain the polyclonal antibody and for evaluation of antigenicity by protein array. Also, the antibody against Pv92 was used for subcellular analysis by immunofluorescence assay. The Pv92 protein has a signal peptide and a sexual stage s48/45 domain, and the cysteine residues at the N-terminal of Pv92 were completely conserved. The N-terminal of Pv92 was successfully expressed as soluble form using a bacterial expression system. The antibody raised against Pv92 recognized the parasites and completely merged with PvMSP1-19, indicating that Pv92 was localized on the merozoite surface. Evaluation of the human humoral immune response to Pv92 indicated moderate antigenicity, with 65% sensitivity and 95% specificity by protein array. Taken together, the merozoite surface localization and antigenicity of Pv92 implicate that it might be involved in attachment and invasion of a merozoite to a new host cell or immune evasion during invasion process.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.386-391
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• 2005

This study was done to produce a mutated protein inactivated cytotoxicity of Shigatoxin 2e (Stx2e) of E.coli O139 isolates by deletional mutagenesis of Stx2e A subunit gene encoding active-site cleft of enzymatic domain in ST2e holotoxin. Cytotoxicity of the toxoid expressed from the mutant Stx2e gene was compared with wild type Stx2e for development of vaccine candidate. A recombinant plasmid pED18 containing Stx2e gene ot E.coli O139 isolates was used to generate mutation plasmid. Deletion mutagenesis was conducted for Stx2e A subunit gene encoding enzymatically active domain by polymerase chain reaction (PCR) using ot designed primer to induce deletional mutation. DNA sequence analysis was confirmed that the pentamer (Typ 202- Ser 206) that lies within the proposed active-site cleft in the second region was completely deleted. A DNA fragment of 1.1 kb that encode the new mutant Stx2eA gene was inserted into plasmid pRSET vector digested with EcoRV-Hind III and named pEDSET The PEDSET was transformed in E. coli for expression of mutant protein and the protein was confirmed by SDS-PACE and Western-blotting. The protein expressed by the mutant was tested to confirm the reduction of cytotoxic activities on Vero cell using microcytotoxicity assay compared with wild type Stx2e, the cytotoxicity of deletional mutant protein was at least reduced by 3,000-fold on Vero cell.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.537-546
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• 2015

Classical swine fever (CSF) is a highly contagious disease of pigs caused by CSF virus (CSFV). E2 is the major viral envelope protein of immune dominance that induces neutralizing antibodies and confers protection against CSFV infection. The B/C domains of E2 are variable among CSFV isolates, which could affect immunogenicity and binding to antibodies. We attempted to characterize the epitope recognized by a monoclonal antibody 2B6 (mAb-2B6) raised against the E2 B/C domains of the vaccine C-strain and to examine if mutations in the epitope region would affect antibody binding and viral neutralization. The epitope specific for mAb-2B6 recognition is linear, spanning five residues ⁷⁷⁴DGXNP⁷⁷⁸ in the B/C domains. The residue N777 is indispensable for the specificity. The epitope exists only in group 1 strains, but not in those of group 2. The recombinant viruses containing individual mutations on the epitope region lost the reactivity to mAb-2B6. The mutant virus RecC-N777S had low replication potential, about 10-fold decrease in the yield of progeny virus particles, whereas the mutant virus RecC-P778A reverted to proline upon continuous passaging. The mutations on the mAb-2B6 epitope region did not affect neutralization by anti-C-strain polyclonal sera from pigs. Deletion from aa774 covering the mAb-2B6 epitope, but not that from aa781, also affected binding with the polyclonal antibodies from vaccinated pigs, although the major binding region for the vaccinated antibodies is aa690-773.

• Journal of Life Science
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• v.33 no.1
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• pp.64-72
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• 2023

Despite several advances in identification of cardiac transcription factors, there are still needs to find new bioactive molecules that promote cardiomyogenesis from stem cells to highly efficient myocardial differentiation. We analyzed Illumina expression microarray data of mouse embryonic stem cells (mESCs)-derived cardiomyocytes. 276 genes were upregulated (≥ 4fold) in mESCs-derived cardiomyocytes compared undifferentiated ESCs. Secreted phosphoprotein 2 (Spp2) is one of candidates and is known to inhibit bone morphogenetic protein 2 (BMP2) signal transduction as a pseudoreceptor for BMP2. However, its function in cardiomyogenesis is unknown. We confirmed that Spp2 expression increased during the differentiation into functional cardiomyocytes using mESCs, TC-1/Kh2 and E14. Interestingly, Spp2 secretion transiently increased 3 days after formation of embryoid bodies (EBs), indicating that the extracellular secretion of Spp2 is involved in the differentiation of ESCs into cardiomyocytes. To characterize Spp2, we performed experiments using the C2C12 mouse myoblast cell line, which has the property of shifting the differentiation pathway from myoblastic to osteoblastic by treatment with BMP2. Similar to the differentiation of ESCs, transcription of Spp2 increased as C2C12 myoblasts differentiated into myotubes. In particular, Spp2 secretion increased dramatically in the early stage of differentiation. Furthermore, treatment with Spp2-Flag recombinant protein promoted the differentiation of C2C12 myoblasts into myotubes. Taken together, we suggest a novel bioactive protein Spp2 that differentiates ESCs into cardiomyocytes. This may be useful for understanding the molecular pathways of cardiomyogenesis and for experimental or clinical promotion of stem cell therapy for ischemic heart diseases.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.857-863
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• 2006

Purpose : To evaluate the immunogenicity of hepatitis B vaccine among very low birth weight infants(VLBWI) who were vaccinated at 0, 1, 6 months of chronological age and to determine the factors associated with antibody formations. Methods : A total of 243 VLBWI admitted to Seoul and Gangneung Asan Medical Center neonatal intensive care units from 1997 to 2004 were included. Of 243, 13 infants were born to HBs Ag positive mother. All infants were given DNA recombinant vaccine at 0, 1, and 6 months of chronological age. Infants born to HBs Ag positive mothers received hepatitis B immunoglobulin at birth and a total of 4 doses of vaccinations. An antibody level over 10 mIU/mL, tested at 3-4 months after last vaccination, was regarded as a positive seroconversion. Results : The seroconversion rates were 84.4 percent and 84.5 percent for VLBWI and extremely low birth weight infants(ELBWI), respectively. Of 28 seronegative infants who were given revaccinations, 60.7 percent seroconverted, resulting in 95.3 percent, 97.5 percent seroconversion rates for VLBWI and ELBWI, respectively. 76.9 percent of infants born to HBsAg positive mothers seroconverted and none became hepatitis B carriers. Factors such as gestational age, sex, various neonatal illness, and kinds of vaccinations did not influence the formation of the hepatits B antibody, however, the higher the weight at time of first vacciation yielded better seroconversion rate. Conclusion : Revaccination of seronegative VLBWI after 3 doses of hepatitis B vaccinaton is very effective. Therefore, testing the immune status after the hepatitis B vaccination, a practice not routinely done, is highly recommended.

• Korean Journal of Veterinary Research
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• v.25 no.1
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• pp.7-17
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• 1985

Many investigators have been pursuing various attempts so far to produce hepatitis B surface antigen(HBsAg) vaccines using the techniques such as isolation from plasma of chronic HBsAg carrier, recombinant DNA technique or preparation of synthetic peptides specific for immunogenic determinants. Hepatitis B virus can not grow on any cell lines by the tissue culture technique at the present time. The plasma of chronic HBsAg carrier is expensive and its source is limited. The HBsAg from the recombinant DNA technique gave still very low yield. Another approach, therefore, has been initiated to develop a synthetic hepatitis B virus vaccine. The possible use of several distinct synthetic vaccines in prophylaxis can be facilitated by availability of full synthetic immunogens. Peptides synthesized for potential application as antiviral vaccines have been mostly tested in the form of conjugates with carrier proteins, although the free synthetic peptide can be immunogenic. To understand basic knowledges on the antigenicity and immunogenicity of a synthetic peptide specific for major immunogenic determinant of HBsAg, a nonapeptide, $H_2N^{139}Cys-Thr-Lys-Pro-Thr-Asp-Gly-^{146}Asn-Aba$ COOH, which corresponds to HBsAg amino acid residues 139 to 147, was synthesized by the Merrifield's solid-phase method with a slight modification. The antigenicity and immunogenicity of this specific synthetic peptide were examined comparing with purified plasma-derived natural HBsAg. The results obtained are as follows; 1. The peptide synthesized showed the identical amino acid composition to the theoretical value. The degree of purification and molecular weight were acertained by methods of high performance liquid chromatography and mass spectrometry. 2. Using m-maleimidobenzoyl-N-hydroxysuccinimide ester as a conjugating agent, the synthetic peptide was conjugated to rabbit albumin and ${\gamma}$-globulin, tetanus and diphtheria toxoids, and keyhole limpet hemocyanin. Their conjugation yields were 8.3, 9.5, 15.8, 13.5, and 11.2%, respectively. 3. The natural HBsAg was purified from plasma of chronic HBsAg carrier. By the electron microscopic observation of the purified natural HBsAg preparation, no Dane particles were observed and the preparation showed negative DNA polymerase activity. 4. Antigenicity of the synthetic peptide and the plasma-derived natural HBsAg was determined by competition radioimmunoassay using $^{125}I$-natural HBsAg. Their 50% inhibitions appeared as $90{\mu}g/ml$ and $0.12{\mu}g/ml$ for the synthetic peptide and the natural HBsAg, respectively. This indicates that the former was about 750-fold less antigenic than the latter. 5. Immunogenicity of the synthetic peptide was determined by administering the peptide-carrier conjugates into rabbits with and without Freund's complete adjuvant. Regardless the carrier proteins and adjuvant, positive immune responses to the synthetic peptide were observed. The higher antibody titers, however, were shown in the groups administered with Freund's complete adjuvant. 6. Immunizing dose 50% in mice of the various peptide-carrier conjugates was 5.47, 6.00, 65.16, 31.25 and $13.03{\mu}g/dose$ for rabbit albumin and ${\gamma}$-globulin, tetanus and diphtheria toxoids, and keyhole limpet hemocyanin, respectively, while the natural HBsAg showed $0.65{\mu}g/dose$. 7. It was postulated that homologous proteins prefer to heterologous ones as the carriers.