Human μ-opioid receptor overexpressed in Sf9 insect cells functionally coupled to endogenous G_(i/o) proteins

Human μ-opioid receptor （HμOR） with a tag of six consecutive histidines at its carboxyl terminus had been expressed in recombinant baculovirus infected Sf9 insect cells.The maximal binding capacity for the [3H] diprenorphine and [3H]ohmefentanyl （Ohm） were 9.1± 0.7 and 6.52±0.23 nmol/g protein, respectively. The [3H] diprenorphine or [3H] Ohm binding to the receptor expressed in Sf9 cells was strongly inhibited by μ-selective agonists [D-Ala2], N-methylPhe4, glyol5]enkephalin （DAGO）, Ohm, and morphine, but neither by δ nor by K selective agonist. Na+ （100 mM） and GTP （50 μM） could reduce HμOR agonists etorphine and Ohm affinity binding to the overexpressed HμOR. μ-selective agonists DAGO and Ohm effectively stimulated [35S]GTPγS binding (EC50 = 2.7nM and 6.9 nM) and inhibited forskolin- stimulated cAMP accumulation (IC50 = 0.9 nM and 0.3 nM). The agonist-dependent effects could be blocked by opioid antagonist naloxone or by pretreatment of cells with pertussis toxin （PTX）. These results demonstrated that HμOR overexpressed in Sf9 insect cells functionally coupled to endogenous Gi/o proteins.

Porcine Interleukin-2 Expression in Insect Cells and Its Enhancement of Pig Immunity to Swine Influenza Virus Inactivated Vaccine

Mature porcine interleukin-2 （pIL-2） gene was amplified by PCR from the plasmid pGEM-T-pIL2 and cloned into the baculovirus pFastBacTM Dual vector of the Bac-to-Bac baculovirus expression system under the control of the PH promoter. Recombinant plL-2 （rpIL-2） expressed in Sf9 insect cells was detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunofluorescence assay. Western blot analysis confirmed that the rpIL-2 protein had a molecular mass of 20 kDa, which was larger than the molecular mass of the mature protein predicted based on its peptide sequence. The rpIL-2 protein induced in vitro proliferation of ConA-stimulated porcine splenocytes and enhanced in vivo protective immune responses induced by vaccinating the pigs with inactivated oil emulsion vaccine against swine influenza virus. The results showed that the rpIL-2 expressed in Sf9 insect cells has immunoenhancement effects; the finding lays the foundation for the preparation of a specific recombinant IL-2 protein and the development of a novel immune adjuvant of vaccines against various infectious porcine pathogens to increase the immunoprotective efficacy of vaccines.

截短的丙型肝炎病毒核心蛋白基因和绿色荧光蛋白基因在Sf9细胞中的融合表达

目的构建含截短的HCV核心蛋白基因和绿色荧光蛋白基因的重组杆状病毒表达载体,探讨其在Sf9细胞中的表达和抗原性。方法用PCR法扩增截短的HCV核心蛋白基因片段(Ct)和增强型绿色荧光蛋白(EGFP)基因,将其插入转座子载体pFastBac1,构建成重组表达载体pFastCt-EGFP,转化大肠埃希菌DH10Bac,获得重组杆状病毒穿梭质粒BacmidCt-EGFP,转染昆虫Sf 9细胞。结果SDS-PAGE和western blot鉴定表明成功表达了分子量约40 000的融合蛋白。以ELISA法检测发现该融合蛋白能与28份抗HCV抗体阳性血清中的15份发生反应,阳性率为53.6%。结论该融合蛋白在昆虫Sf 9细胞中成功表达并具有一定的抗原性。

Expression of Rice Gall Dwarf Virus Outer Coat Protein Gene (S8) in Insect Cells

To obtain the P8 protein of Rice gall dwarf virus (RGDV) with biological activity,its outer coat protein gene S8 was expressed in Spodoptera frugiperda (Sf9) insect cells using the baculovirus expression system.The S8 gene was subcloned into the pFastBacTM1 vector,to produce the recombinant baculovirus transfer vector pFB-S8.After transformation,pFB-S8 was introduced into the competent cells (E.coli DH10Bac) containing a shuttle vector,Bacmid,generating the recombinant bacmid rbpFB-S8.After being infected by recombinant baculovirus rvpFB-S8 at different multiplicities of infection,Sf9 cells were collected at different times and analyzed by SDS-PAGE,Western blotting and immunofluorescence microscopy.The expression level of the P8 protein was highest between 48-72 h after transfection of Sf9 cells.Immunofluorescence microscopy showed that P8 protein of RGDV formed punctate structures in the cytoplasm of Sf9 cells.

庚型肝炎病毒NS3蛋白在杆状病毒载体中的表达及其抗原性研究

目的 :利用 Bac- to- Bac HT杆状病毒系统在 Sf9昆虫细胞中表达庚型肝炎病毒 (HGV) NS3蛋白 ,并对表达产物的免疫原性进行研究。 方法 :将 HGV NS3基因片段定向克隆至转座载体 p Fast Bac HTa,转化 DH10 Bac感受态细胞 ,37℃振荡培养 4h使发生转座 ,用抗生素平皿筛选重组 bacmid。脂质体介导转染 Sf9昆虫细胞 ,待细胞形态明显改变后收获细胞和培养上清液 ,将上清液再次感染 Sf9细胞以大量表达 HGV NS3重组蛋白。利用 SDS- PAGE和 Western- blotting方法分析重组蛋白。结果 :SDS- PAGE分析发现表达产物在 Mr43810处有一条明显的蛋白带 ,占细胞总蛋白量的 30 %以上 ;应用 Ni- NTA亲和层析柱获得了纯化的重组蛋白 ;Western- blotting显示该抗原可与 HGV RNA阳性血清发生特异反应。 结论 :获得了昆虫细胞内表达的 HGV NS3重组蛋白 ,并证明该蛋白有可能用于 HGV感染的抗体检测。

MPB64在杆状病毒系统中的表达纯化及免疫原性鉴定

目的：在杆状病毒昆虫细胞表达系统中表达结核分枝杆菌蛋白MPB64，并鉴定其免疫原性。方法：目的基因MPB64连接到pFastBac载体，获得pFastBac-MPB64质粒转化DH10 Bac感受态，通过Tn7转座片段将目的基因转座到Bacmid中，得到Bacmid-MPB64穿梭载体，脂质体包被后转染Sf 9细胞收获P1代病毒，重复转染Sf 9细胞三次获得高滴度的P4代病毒，收集细胞上清通过Q Sepharose FF和Ni亲和层析柱两步层析纯化得到目的蛋白MPB64。纯化的蛋白免疫BALB／c小鼠并检测血清中抗体滴度，ELISA检测MPB64蛋白刺激脾脏细胞产生IFN-γ的浓度，MTT法检测目的蛋白对免疫后小鼠脾脏细胞的增殖作用。结果：MPB64在昆虫细胞中成功表达，纯化后蛋白纯度达90％以上，蛋白产量为35 mg／L，纯化蛋白能有效刺激BALB／c小鼠产生抗体，提高小鼠脾脏细胞培养基中IFN-γ的含量，目的蛋白在0.2～100μg／ml之间对脾脏细胞有明显的促增殖作用。结论：成功在杆状病毒昆虫细胞表达系统中表达了具有免疫原性的MPB64蛋白，为生产结核病疫苗奠定了基础。

HCV核心和截短的包膜蛋白E2基因在昆虫细胞中的表达及其抗原性

目的 :构建含 HCV全长核心基因和截短的包膜蛋白 E2基因的重组杆状病毒表达载体 ,研究其表达和抗原性。 方法 :以含 HCV全长 c DNA克隆的 p GEM- HCJ4质粒为模板 ,PCR扩增全长的 HCV核心抗原基因和截短的 E2基因片段 ,插入转座载体 p Fast Bac HTa构建重组转座质粒 p FB- CE2 t,转化 DH10 Bac大肠杆菌 ,获得重组杆状病毒穿梭质粒 Bacmid- CE2 t,以之转染昆虫 Sf9细胞进行外源基因的表达 ,并对其抗原性进行 EL ISA检测。 结果 :SDS- PAGE和 Western blot分析表明Bacmid- CE2 t在 Sf9细胞表达了 HCV C- E2蛋白 ,并能利用细胞内蛋白酶将其裂解为单独的 C蛋白和截短的 E2蛋白。纯化后的蛋白能分别与 HCV C蛋白、E2蛋白单抗以及慢性丙型肝炎患者血清反应。 结论 :HCV核心蛋白和截短的

草地贪夜蛾(Spodoptera frugiperda)细胞在生物反应器中培养条件初探

对草地贪夜蛾（ Ｓｐｏｄｏｐｔｅｒａ ｆｒｕｇｉｐｅｒｄａ） Ｓｆ９ 细胞在２ Ｌ Ｂｉｏｓｔａｔ Ｒ Ｍ Ｄ 型搅拌式生物反应器中进行了培养，并对细胞的生长状况、葡萄糖的消耗等进行了测定；对重组病毒的增殖、外源基因的表达进行了初步探索．结果表明：细胞在该生物反应器中生长良好，细胞群体倍增时间３３．４ ｈ．病毒感染率大约在 ８９．８％ 以上。