• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1670-1674
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• 2007

Duffy binding protein (DBP) plays a critical role in Plasmodium vivax invasion of human red blood cells. We previously reported a single-chain antibody fragment (scFv) that was specific to P. vivax DBP (PvDBP). However, the stabilization and the half-life of scFvs have not been studied. Here, we investigated the effect of PEGylated scFvs on their biological activity and stability in vitro. SDS-PAGE analysis showed that three clones (SFDBII-12, -58, and -92) were formed as monomers (about 70 kDa) with PEGylation. Clone SFDBII-58 gave the highest yield of PEGylated scFv. Binding analysis using BIAcore between DBP and scFv showed that both SFDBII-12 and -58 were decreased approximately by two folds at the level of binding affinity to DBP after PEGylation. However, the SFDBII-92 clone still showed a relatively high level of binding affinity ($K_D=1.02{\times}10^{-7}\;M$). Binding inhibition assay showed that PEGylated scFv was still able to competitively bind the PvDBP and playa critical role in inhibiting the interactions between PvDBP protein expressed on the surface of Cos-7 cells and Duffy receptor on the surface of erythrocytes. When both scFvs and their PEGylated counterparts were exposed to trypsin, scFv was completely degraded only after 24 h, whereas 35% of PEGylated scFvs remained intact, maintaining their stability against the proteolytic attack of trypsin until 72 h. Taken together, these results suggest that the PEGylated scFvs retain their stability against proteolytic enzymes in vivo, with no significant loss in their binding affinity to target antigen, DBP.

• Parasites, Hosts and Diseases
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• 제49권1호
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• pp.85-90
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• 2011

Relatively little has been studied on the AMA-1 vaccine against Plasmodium vivax and on the plasmid DNA vaccine encoding P. vivax AMA-1 (PvAMA-1). In the present study, a plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax has been constructed and a preliminary study was done on its cellular immunogenicity to recipient BALB/c mice. The PvAMA-1 gene was cloned and expressed in the plasmid vector UBpcAMA-1, and a protein band of approximately 56.8 kDa was obtained from the transfected COS7 cells. BALB/c mice were immunized intramuscularly or using a gene gun 4 times with the vaccine, and the proportions of splenic T-cell subsets were examined by fluorocytometry at week 2 after the last injection. The spleen cells from intramuscularly injected mice revealed no significant changes in the proportions of CD8$^+$ T-cells and CD4$^+$ T-cells. However, in mice immunized using a gene gun, significantly higher (P<0.05) proportions of CD8$^+$ cells were observed compared to UB vector-injected control mice. The results indicated that cellular immunogenicity of the plasmid DNA vaccine encoding AMA-1 of the reemerging Korean P. vivax was weak when it was injected intramuscularly; however, a promising effect was observed using the gene gun injection technique.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.95-95
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• 1997

Among the various receptor molecules discovered so far the ${\beta}$2-adrenergic receptors have been regarded as excellent model systems for the so called 7 transmembrane helix receptor and have been the focus of extensive studies. For the analysis of receptor structure and function a monoclonal antibody plays a crucial role, thus providing useful tools for the study of receptor. However, because of the minute quantity of receptor molecules which could be obtained from natural sources, the generation of specific monoclonal antibody against receptor molecules from the purified receptors has been regarded as virtually impractical in consideration of cost and experimental times. The purpose of the present study was to generate and characterize a monoclonal antibody against human ${\beta}$2-adrenergic receptor. For the production of antibody, C-terminal regions of the human ${\beta}$2-adrenergic receptor was produced as a fusion protein with Glutathion S-transferase (GST) in E. Coli. The expression of the fusion protein was identified by SDS-PAGE and Western blot using monoclonal anti-GST antibody. The fusion protein was purified to an apparent homogeniety by affinity chromatography with Glutathion Sepharose CL-4B and used as an antigen for the immunization of BALB/C mice. The Production of monoclonal antibody was achieved by fusion of the immunized spleen cells and SP/2-0 myeloma cells. Positive hybridomas were screened by ELISA and were cloned by two consecutive rounds of limiting dilution. The monoclonal antibody produced in this study (mAb${\beta}$C02) was IgM type and purified by immunoaffinity chromatography using anti-mouse IgM agarose as an affinity matrix. MAb${\beta}$C02 showed strong and specific immunoreactivity against both the fusion protein and human ${\beta}$2-adrenergic receptor in ELISA and Western blot. The molecular weight of immunoreactive band was 64 kDa and exactly coincided with the previously reported molecular weight of ${\beta}$2-adrenergic recepters. The results of the present study suggest that mAb${\beta}$C02 may be used for the study of receptor function and regulation in normal or nonphysiological status.

• Tuberculosis and Respiratory Diseases
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• 제61권3호
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• pp.239-247
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• 2006

연구배경: Mycobacteria 배양액 여과 단백질은 결핵에 대한 세포성 면역반응 및 진단 연구에 중요한 역할을 하는 것으로 알려져 있다. 새로운 결핵균 특이 유전자를 클로닝하여 약 14-kDa의 결핵균 재조합 단백질(TB-14)을 분리 정제 한 뒤 전혈 배양(whole blood culture)을 통해 재조합 단백질 항원의 자극에 따른 IFN-${\gamma}$ 분비 유도를 PPD와 비교 측정하여 TB-14 단백질이 결핵균에 대한 숙주의 세포성 면역반응 유도에 어떤 역할을 하는 지를 알아보고자 하였다. 방 법: M. avium 배양 여과액에서 항혈청과 강하게 반응하는 하나의 M. avium 특이 단백질을 확인하여 아미노산 서열을 규명한 뒤 이 단백질과 높은 상동성을 나타내는 M. tuberculosis 유전자를 클로닝하여 다량의 결핵균 재조합 단백질(TB-14)을 분리 정제하였다. 재조합 단백질 TB-14에 대한 세포성 면역 반응 유도를 알아보기 위해 결핵 환자(9명), PPD 양성 정상인(7명) 및 PPD 음성 정상인(7명)들로부터 얻은 전혈(whole blood)를 RPMI로 희석한 뒤 $10{\mu}g$의 PPD와 TB-14 단백질로 48 시간 동안 자극하여 상층액에 분비된 IFN-${\gamma}$ 농도를 ELISA로 측정하였다. 결 과: 1. M. avium LR114F 균주의 배양 여과액 내에서 M. intracellulare 항혈청에 강하게 반응하는 새로운 M. avium 특이 단백질을 규명하여 아미노산 서열을 확인하였다. 2. M. avium 특이 단백질과 상동성을 보이는 M. tuberculosis 특이 재조합 단백질인 TB-14은 148개의 아미노산으로 구성되어 있고 30개의 아미노산으로 이루어진 signal peptides를 가지며 M. avium과 78%의 상동성을 보였다. 3. PPD 양성인의 전혈 배양에서 TB-14 단백질 항원으로 자극된 군에서 PPD로 자극된 군보다 월등히 높은 IFN-${\gamma}$ 분비를 나타내었다. 반면 결핵환자에서는 질환의 양상이나 치료 정도에 따라 IFN-${\gamma}$의 분비 양상이 일정하지 않았다. 결 론: 새로운 결핵균 특이 재조합 단백질 TB-14는 결핵에 대한 인체 내 세포성 면역반응 유도에 중요한 역할을 할 수 있는 단백질이라 생각되며 특히 PPD 양성자에서 높은 IFN-${\gamma}$의 분비 양상을 보여 정상인과 결핵 감염자의 감별진단에도 활용될 수 있으리라 생각된다. 또한 TB-14 단백질에 대한 항혈청을 제작하여 환자의 가검물에 분비되는 결핵균 특이 단백질을 탐색하는 결핵의 진단 연구에도 활용될 수 있을 것으로 사료된다.