Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea and dehydration in pigs with high mortality. PEDV is belong to Coronavirus, enveloped, single-stranded, positive-sense RNA virus. PEDV particles were composed of four structure proteins such as a glycosylated peplomer (spike, S) protein, envelope (E), glycosylated membrane (M) protein, and unglycosylated RNA-binding nucleocapsid (N) protein. Many of previous studies talk about this four structure proteins have a great potential to diagnosis and prevent PEDV. In this study we investigated expression of these structure proteins using the bacterial and baculovirus expression system. In bacterial expression system, our results showed that structure proteins fused polyhedrin and intein gene were expressed higher than non-fusion structure proteins. The expressed fusion proteins were used to immune mice for generating a polyclonal antibodies. In baculovirus expression system, co-infection of insect cells with these four recombinant baculoviruses led to self-assembly of virus-like particles as demonstrated by Transmission electron microscopy. They were confirmed by western blot analysis using pre-made polyclonal antibodies. Finding in this study may provide important information for vaccine and diagnostic development.

Polyhedrin is the major component of the nuclear viral occlusions produced during replication of the baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). To enhance the production efficiency of foreign protein in baculovirus expression system, the effects of various polyhedrin fragments were investigated by fusion expressing them with the enhanced green fluorescent protein (EGFP). Recombinant viruses were generated to express EGFP fused with polyhedrin fragments based on the previously reported minimal region for self-assembly and the KRKK nuclear localization signal (NLS). The marked increase of EGFP by these fusion expressions was confirmed through protein and fluorescence intensity analyses. Among the fusion-expressed protein in nucleus and cytoplasm, the most hyper-expression was observed in the fusion of amino acids 19 to 110 and 32 to 59 of polyhedrin. Also these fragments, some degradation of only the fused polyhedrin was observed in the fusion of amino acids 19 to 85 and 32 to 85. The production of E2 protein, which is a major antigen of classical swine fever virus, was dramatically increased by fusion expression with polyhedrin amino acids 19 to 110, and its preliminary immunogenicity was verified using experimental guinea pigs. The production of luciferase was approximately two folds increased by fusion expression with polyhedrin amino acids 32 to 59, and its activity was measured using Luminometer. This study suggests a new option for higher expression of useful foreign recombinant protein using the partial polyhedrin fusion expression in baculovirus.

Colorectal cancer is the third most commonly diagnosed cancer in the world, nearly all patients diagnosed with this cancer die from it. Antibodies are glycoprotein molecules, which can efficiently recognize and eliminate specific pathogenic and disease antigens. Antibody researches for the last several decades have demonstrated the potential of therapeutic antibodies to fight cancer. Monoclonal antibody (mAb) CO17-1A recognizes the tumor-associated antigen GA733-2, a cell surface glycoprotein highly expressed in colorectal carcinoma cell, which is applicable for preventing and curing colorectal cancer. We have currently established baculovirus insect cell expression system to produce anti-colorectal cancer mAb CO17-1A. In this study, mAb CO17-1A was expressed in the transgenic insect cell line SWT4, which has humanized glycosylation processing pathway. Immunoblot confirmed that mAb CO17-1A properly expressed in SWT4. mAb CO17-1A was purified using protein G affinity column. In addition, Maldi-TOF verified that the mAb fused to KDEL, ER retention signal had high mannose type of glycan structure whereas the mAb without KDEL had partially humanized glycan structure. These results suggest that the insect cell expression system with the SWT4 possibly can be used as a useful alternative way to produce full-size mAb with humanized glycan structures for cancer immunotherapy.

Aujeszky's disease (AD), also called pseudorabies, is an infectious viral disease caused by an alpha herpes virus and has domestic and wild pigs, as well as a wide range of domestic and wild animals, as the natural host. Aujeszky's disease virus (ADV) virions contain several envelope glycoproteins. Among them, glycoproteins gB, gC and gD are regarded as the major immunogenicity proteins and the antibodies induced by them can neutralize virus in vitro or in vivo. In this study, we investigated expression of these glycoproteins using the bacterial and baculovirus expressionn system. Successful expression of ADV glycoproteins in E. coli was confirmed by SDS-PAGE and Western blot analysis and their optimal expression condition was determined. However, the recombinant proteins generated in the bacterial expression system which lacks glycosylation process frequently lose their biological activity. We tried to express the ADV glycoproteins using the baculovirus expression vector system. The recombinant gB, gC and gD were detected at approximately 100, 60 and 50 kDa on SDS-PAGE and Western blotting, respectively. The optimal expression conditions were determined for MOI(multiplicity of infection) and post-infection days. One MOI and 4 or 5 days post-infection were the best conditions for the expression of the ADV glycoproteins in Sf21 cells. We are currently investigating the antigenicity of recombinant proteins using experimental animals.

The Classical Swine Fever Virus (CSFV) is a member of the Pestivirus genus of the Flaviviridae. The genome of CSFV is a positive single-stranded RNA molecule 12.3 kb and contains a single large open reading frame (ORF). The polyprotein composed of eight nonstructural and four structural proteins (nucleocapsid protein C and three envelope glycoprotein E0, E1 and E2). E2, the most immunogenic of the CSFV glycoproteins, induces a protective immune response in swine. To determine the characteristics of the CSFV, LOM strain, we investigated the nucleotide sequence of the glycoprotein E0, E1 and E2. Comparison of the LOM with the other strains revealed nucleotide sequence identity ranging from 97 to 98%. Expression of the glycoprotein E2 was identified by SDS-PAGE and Western blot analysis using anti-CSFV E2 monoclonal antibodies in Sf21 cells. The expression levels of glycoprotein E2 were observed from day 3 and 5 days maximum. In addition, its expression efficiency by media and cell line was investigated. The result showed that High-Five cells and Grace’s insect media for Sf21 were the best conditions for the expression of the glycoprotein E2.

Autographa californica 핵다각체병 바이러스(AcNPV)의 다각체 단백질과 초록색 형광 단백질의 융합단백질의 특성을 분석하였다. 초록색 형광 단백질 유전자는 AcNPV의 완전한 다각체 단백질 유전자의 앞쪽과 뒤쪽에 융합하여 다각체 단백질 유전자의 프로모터 조절하에 도입하였다. 이렇게 작성된 재조합 바이러스를 각각 Ac-GFPPOL 또는 Ac-POLGFP이라고 명명하였다. 이들 재조합 바이러스에 의해 감염된 곤충세포주에서는 56kDa의 융합단백질이 발현되었다. 한편, 흥미롭게도 재조합 바이러스 Ac-POLGFP에 의해 감염된 세포주에서는 초록색 형광이 핵내에서만 다각체 유사 granular particle 형태로 관찰되었다. 반면에 Ac-GFPPOP에 의해 감염된 세포도주에서는 대부분 핵내에 존재하였지만, 세포질과 핵 모두에서 초록색 형광을 관찰할 수 있었다. 그러나 발현된 융합단백질은 분명히 다각체단백질을 포함하고 있음에도 다각체는 형성하지 않았다. 이러한 결과들은 융합단백질에서 다각체단백질의 위치와 관련이 있는 것으로 보여진다.

남부지방에서 분리한 곤충병원성곰팡이 Beauveria bassiana GY1-17균주를 이용하여 산림해충인 오리나무잎벌레(Agelastica coerulea), 밤나무혹나방(Meganola melancholica), 회양목명나방(Glyphodes perspectalis), 잔디해충인 등얼룩풍뎅이(Blitopertha orientalis), 채소해충인 배추좀나방(Plutella xylostella) 및 거세미나방(Agrotis segetum)의 생물적 방제 가능성을 알아보기 위하여 실험한 결과, 오리나무잎벌레와 배추좀나방유충은 7.0~2.0 conidia/ml 농도에서 처리 7일과 5일후 100%의 치사율을 나타내었다. 밤나무혹나방유충은 0.03875~3.1 conidia/ml 처리에서 66.7~100%의 높은 치사율을 보였으나 회양목명나방유충은 2.0~2.0conidia/ml 처리에서도 전혀 치사되지 않았다. 등얼룩풍뎅이유충은 3.7 conidia/ml 농도에서 46.7%의 치사율을 보였고, 거세미나방유충은 2.5 conidia/ml 농도에서 63.3% 치사율을 나타내었다.