我国马铃薯抗病毒基因工程研究进展

10年来我国已合成克隆了PVX、PVY、PLRV的外壳蛋白基因 ,复制酶基因 ,蛋白酶基因 ,基因调控序列 ,核酶cDNA及其他各种基因并进行了序列分析。建立了完善的致瘤农杆菌介导的马铃薯转化技术。通过外壳蛋白基因介导 ,复制酶基因介导 ,表达基因调控序列和核酶等基因工程途径 ,获得了一批不同程度上抗PVX、PVY、PVX和PVY ,PVY和PLRV ,PLRY及高抗PSTVd的转基因马铃薯栽培种。这些转基因马铃薯多数已进入田间试验。不久一批抗病毒的优质高产的马铃薯栽培种 ,经过进一步发育 ,必将在生产中推广应用。抗病毒转基因马铃薯培育成功 ,为我国马铃薯病毒病害防治开辟了一条崭新的途径 。

Cloning and Prokaryotic Expression of NS1 Gene of Porcine Parvovirus (PPV) SD1 Strain

[Objective] The research aimed to provide the theoretical basis for establishing a rapid diagnosis method for porcine parvovirus（PPV）. [ Method] One pair of primers were designed according to PPV genome sequences on GenBank website and the sequences of prokaryotic expression vector pET30a （ ＋ ） with multiple cloning sites. The whole sequence of NS1 gene in PPV SD1 strain was amplified by using PCR technology and the positive recombinant plasmid was analyzed by sequencing and homology comparison. The prokaryotic expression recombinant plasmid PET30a/NS1 was constructed to make its induction expression in Escherichia coll. [ Result] The target fragment with the length of 2 208 bp was obtained from PCR amplification. The nucleotide homologies between the cloned NS1 gene and the reported relevant PPV genes were from 97.3 % to 99.4 %, which indicated that NS1 gene had high conservation. But it had a 12-basepair successive deletion near the hydroxyl end. The cloned PPV NS1 gene was successfully expressed in prokaryotic cell, and its expression products existed mostly in inclusion bodies. [ Conclusion] The results of SDS-PAGE detection showed that the molecular weight of PPV NS1 protein was 86 KD.

Cloning and Phylogenetic Analysis of NS1 Genes from Different Isolates of H9N2 Subtype Duck Influenza Virus

[ Objective] The study aimed to lay a foundation for the further studies on function mechanism of NS1 protein in the interspecies transmission of waterfowl influenza virus. [Method] Using the serologic assay and the specific RT-PCR method, some strains of H9 subtype waterfowl influenza virus were isolated from the 12 to 20 day-old muscovy duck flocks without any clinical symptoms in different areas of Guangdong Province. Four of these strains, including A/duck/ZQ/303/2007（H9N2） （A3 for short）, A/Duck/FJ/301/2007 （H9N2） （C1 for short）, A/Duck/NH/306/2007（H9N2） （ D6 for short）, A/duck/SS/402/2007（H9N2） （ E2 for short）, and a strain named A/duck/ZC/2007（H9N2） （L1 for short） from a muscovy duck died of avian influenza virus （AIV）, were used for NSl gene cloning and sequencing. Subsequently, the obtained NSl gene sequences were compared with other NS1 sequences registered in GenBank, and the phylogenetic analysis was also conducted. [Result] When compared with the H9N2 AIV NS1 sequences in GenBank, the NSl genes of the four AIV strains A3, C1, 136 and E2 displayed homologies ranging from 99% to 100% at nucleotide level, and 95% to 100% at amino acid level; while the NSl gene of L1 strain displayed homology ranging from 94% to 97% at nucleotide level, and 93% to 98% at amino acid level. The phylogenetic tree demonstrated that A3, C1, D6 and E2 were highly resemblant, and L1 was closest to AY66473 （chicken, 2003）. By comparison with the NS1 gene sequences of L1, AF523514 （duck）, AY664743 （chicken） and EF155262.1 （quail） using DNAstar, A3, C1, D6 and E.2 presented nucleotide variations at site 21 （ R→Q）, 70, 71 （ KE→EG）, 86 （ A→S）, 124 （V→M） and 225 （ S→N）, and amino acid variations at site 21,70, 71 and 86 in dsRNA- dependent protein kinase （PKR） binding domain of NSl gene, which induced the evident variations of antigenic determinant and surface proba- bility plot of NS1 protein. [ Conclusion] This study suggested that the amino acid sequence variation in PKR binding domain of NS1 protein had something to do with the virus pathogenicity.

Cloning the Structure Genes and Expression the N Gene of Porcine Epidemic Diarrhea Virus DX

The structure genes spike(S) ,nucleocapsid(N) ,membrane(M) ,small membrane(sM) of a porcine epidemic diarrhea virus(PEDV) strain DX isolated in Gansu province,North-west of China,were cloned,sequenced and compared with published sequences of PEDV strains. The nucleotide sequences encoding the entire S,sM,M and N genes open reading frame(ORF) of DX were 4 152,231,681 and 1 326 bases long respectively. There were transcription regulatory sequences(TRSs) upstream of the initiator ATG of the S,N and M genes. The amino acids sequences of S,M and N contained 30,3 and 7 potential asparagine(N) -linked glycosylation sites. Homologous analysis and phylogenetic trees showed that DX had the closest relationship with strains LJB/06,JS-2004-2Z and CH/HLJH/06 that were also isolated from China and indicated the prevalence of some PEDV isolates in China were widespread since the JS-2004-2Z strain originated from the south of the China,and LJB/06 and CH/HLJH/06 were isolated from northeast China. The N gene was cloned using two primers which contained Nco I and BamH I restriction enzyme sites and subcloned into expression vector pET30a. The recombinant plasmid was then transformed into E.coli Rossta. SDS-PAGE showed there was a protein of about 55kDa as expected and Western blot indicated the N protein had biological activity.

Transactivating effect of complete S protein of hepatitis B virus and cloning of genes transactivated by complete S protein using suppression subtractive hybridization technique

AIM: To investigate the transactivating effect of complete S protein of hepatitis B virus (HBV) and to construct a subtractive cDNA library of genes transactivated by complete S protein of HBV by suppression subtractive hybridization (SSH) technique and to clone genes associated with its transactivation activity, and to pave the way for elucidating the pathogenesis of hepatitis B virus infection. METHODS: pcDNA3.1(-)-complete S containing full-length HBV S gene was constructed by insertion of HBV complete S gene into BamH I/Kpn I sites. HepG2 cells were cotransfected with pcDNA3.1(-)-complete S and pSV-lacZ. After 48 h, cells were collected and detected for the expression of β-galactosidase (β-gal). Suppression subtractive hybridization and bioinformatics techniques were used. The mRNA of HepG2 cells transfected with pcDNA3.Incomplete S and pcDNA3.1(-) empty vector was isolated, and detected for the expression of complete S protein by reverse transcription polymerase chain reaction (RT-PCR) method, and cDNA was synthesized. After digestion with restriction enzyme RsaI, cDNA fragments were obtained. Tester cDNA was then divided into two groups and ligated to the specific adaptors 1 and 2, respectively. After tester cDNA had been hybridized with driver cDNA twice and underwent nested PCR twice, amplified cDNA fragments were subcloned into pGEM-Teasy vectors to set up the subtractive library. Amplification of the library was carried out within E. coli strain DH5α. The cDNA was sequenced and analyzed in GenBank with BLAST search after polymerase chain reaction (PCR) amplification. RESULTS: The complete S mRNA could be detected by RT-PCR in HepG2 cells transfected with the pcDNA3.1(-)-complete S. The activity of β-gal in HepG2 cells transfected with the pcDNA3.1(-)-complete s was 6.9 times higher than that of control plasmid. The subtractive library of genes transactivated by HBV complete S protein was constructed successfully. The amplified library contains 86 positive clones. Colony PCR showed that 86 clones contained DNA inserts of 200-1 000 bp, respectively. Sequence analysis was performed in 35 clones randomly, and the full length sequences were obtained with bioinformatics method and searched for homologous DNA sequence from GenBank, altogether 33 coding sequences were obtained. These cDNA sequences might be target genes transactivated by complete S protein of HBV. Moreover, two unknown genes were discovered, full length coding sequences were obtained by bioinformatics techniques, one of them was named complete S transactivated protein 1 (CSTP1) and registered in GenBank (AY553877). CONCLUSION: The complete S gene of HBV has a transactivating effect on SV40 early promoter. A subtractive cDNA library of genes transactivated by HBV complete S protein using SSH technique has been constructed successfully. The obtained sequences may be target genes transactivated by HBV complete S protein among which some genes coding proteins are involved in cell cycle regulation, metabolism, immunity, signal transduction, cell apoptosis and formation mechanism of hepatic carcinoma.

Molecular Characterization of a Highly Pathogenetic Porcine Reproductive and Respiratory Syndrome Virus Variant in Hubei, China

Porcine reproductive and respiratory syndrome virus (PRRSV) has been recognized as one of the most important pathogens of pigs throughout the world. In 2006, more than 10 provinces of China have experienced an epizootic outbreak of pig diseases characterized by high fever, reddened skin and high morbidity and mortality. From June 2006 to April 2007, we have investigated some clinical samples in Hubei province by RT-PCR and cloned several major genes, N, GP5 and NSP2 gene, shown in this study. Phylogenetic analysis of these genes revealed that the highly pathogenic PRRSV variant, ZB, was responsible for 2006 emergent outbreak of pig disease in Hubei province similar with those variants isolated from other provinces in China in 2006, and belongs to the NA-type PRRSV. In the PRRSV variants, the N and GP5 shear about 90% identity with prototypic ATCC VR-2332 and some typical NA-type Chinese isolates, except the 2850bp NSP2 gene (only shares 65% identity with ATCC VR-2332). But they all shear more than and 97% identity with other highly pathogenetic Chinese PRRSV strains. Additionally, there are extensive amino acid (aa) mutations in the GP5 protein and 2 deletions in the Nsp2 protein when compared with the previous isolates. Most of the variants found in 2006 epizootic outbreak of pig diseases in China were the farthest variants from the typical NA-type PRRSV in phylogenetic distance, and these diversities may be responsible for the differences in the pathogenicity observed between these variants and original Chinese PRRSV strains.

Molecular Characterization of the Duck Enteritis Virus UL4 Gene

Duck enteritis virus(DEV) is a herpesvirus that causes an acute,contagious and fatal disease. In the present article,the DEV UL4 gene was cloned and sequenced from a vaccine virus. A degenerate oligonucleotide primer for the consensus site of herpesvirus UL3 gene and a specific primer located in UL5 were used in the polymerase chain reaction(PCR) to amplify a DNA product 2 086 bp in size. DNA sequence analysis revealed that a 714 bp open reading frame(ORF) of DEV encoding a 237 amino acid polypeptide is homologous to the family of herpesvirus UL4 proteins and therefore has been characterized as a DEV UL4 gene. Alignment of the DEV UL4 protein sequence with those of other alphaherpesviruses showed that 10 amino acid residues are completely conserved. Phylogenetic tree analysis showed that the seventeen alphaherpesviruses viruses analyzed were classified into four large groups,and the duck enteritis virus branched separately,closely related to the Mardiviruses group comprising Gallid herpesvirus 2(GaHV-2) ,Gallid herpesvirus 3(GaHV-3) and Meleagrid herpesvirus 1(MeHV-1) . The present study showed that the evolutionary relationship of the UL4 protein could be used for classification of alphaherpesviruses.

Cloning and sequence analysis of E2 gene of bovine viral diarrhea virus HB-DCZ strain in Hebei province of China

The objective of this paper was to analyze the E2 genetic characterization of HB-DCZ strain of Bovine viral diaxrhca Virus （BVDV） which wcrc amplified by RT-PCR and isolated from China. The product of PCK was cloned into pMD18-T vector, and then transfected Escherichia Coli JMI00. The recombinant plasmids were amplified by PCR and were sequenced. From the nucleotide sequence of the amplified products, phylogenetie analyses were performed and genotypes or subgenotypes were identified. The results indicated that the E2 gene fragment of HB-DCZ strain contained 1277bp nucleotides, and had 89.4%, 70.7%, 97.6%, 68.9%, 67.2% sequence similarity with Osloss, OregonC24V, Changchun184, ZM195, NADL, respectively. In conclusion, HB-DCZ strain is closely related to BVDV Osloss, Changchun184, and belongs to subgenotype lb.

Cloning and Sequence Analysis of Envelope Glycoprotein E1 Gene of Rubella Virus, JR23 Strain

To construct an expression vector containing the E1 glycoprotein gene of rubella virus for the study on the effect of mutation of the E1 gene glycoprotein and the analysis of phylogenetic differences of sequences, the gene encoding the E1 envelope glycoprotein was amplified from rubella virus, Jinan strain JR23, by RT-PCR and ligated into PMD-18T vector. The clones that carried the E1 gene were identified after amp r selection and analysis of restriction enzyme digestion. After sequencing this gene was analyzed by Danstar and Winstar programs, and the map of phylogenetic tree was drawn. The clone of E1 glycoprotein was thus constructed. It was found that the sequence differences between JR23 strain and the TCRB strain from Japan and those between JR23 strain and Thomas strain of England were rather small with difference values of 0.9% and 1.2% respectively. Yet those between JR23 strain and BRD2 strain from Beijing and those between JR23 strain and XG379 strain from Hong Kong were comparatively larger with difference values of 7.6% and 7.3% respectively. The sequence of JR23 strain with other strains was less than 3% except the NC strain (3.7%). It concludes that the construction of E1 glycoprotein gene offers an approach to study the relationship between structures and functions of E1 gene and its gene products. In the phylogenetic tree, it shows that there are significant differences in the sequences of rubella virus isolated in China, and this might be helpful to develop an effective subunit vaccine.

Studies on the cloning genomec5 of BBTV in Guangzhou areas and its expression in transgenic banana

The DNA was isolated from banana bunchy top virus （BBTV） in Guangzhou areas and a l.lkb DNA of replicas of BBTV was obtained by PCR using this virus DNA as templates for amplification. This reformed DNA of the BBTV replicas which being homologous to 90% with the Australia＇s encoded the C-Terminal of BBTV replicas. The reformed BBTV replicas were cloned to pBI121 in the position between CaMV 35S promoter and NOS termination sequence, and a plant-expressed carder was established. Four transgenic bananas with the expression of BBTV replicase gene in To generation were detected with PCR and Western blot analysis. The ability of these transgenic bananas against bunchy top virus is being analyzed.

Antigen Gene Cloning and Expression of HIV-1 for AIDS Vaccine Design Ⅲ. HIV-1 Antigen Gene Cloning, in Vitro Expression and Antibody Induction

Objective: To evaluate the humoral immune induction in rats of a candidate AIDS vaccine expressing the gag p24 gene froma subtype B HIV-1 isolate. Methods: The amplified p24 gene was inserted into aneukaryotic expression vector to form the supercoiled DNAvaccine. The linearized expressed DNA vaccine was preparedfrom the expression plasmid by polymerase chain reaction(PCR). The antigen gene expression in rats of the linearizedand supercoiled DNA vaccines were in vitro and in vivodetected. Results: In vitro transcription and Northern hybridizationshowed that the linearized DNA vaccine could synthesizeamounts or p24 mRNA similar to the supercoiled DNA vaccine.Antibody assays of inoculated rats confirmed that thelinearized expression DNA could induce a slightly higherantibody titer than the expression plasmid, while the highestautibody titer had been induced by plasmid plus adjuvantinoculation. Conclusion: The construction of a candidate AIDS vaccinebased on the p24 gene could shed light on a potential IV vaccine, meriting evaluation in a rhesus macaque SHIV-AIDSmodel.

Cloning Envelope Gene of Dengue Virus Type 3 （Indonesia D3-1703 Strain） into pYES2/CT Vector

The global burden caused by dengue has increased dramatically in recent decades. Dengue Fever and its severe clinical manifestation, Dengue Hemorrhagic Fever and Dengue Shock Syndrome, have become international public health problem endemic in more than 100 countries, risking 2.5 to 3 billion world populations in tropical and subtropical region. Envelope （E） protein of dengue virus has been proposed as the most important antigen that enables it as vaccine candidate or diagnostic materials. Recombinant protein E production is desirable for dengue vaccine and diagnostic development, especially in Indonesia, where dengue is epidemic. Cloning E gene in an expression vector is essential as an initial method to produce dengue E antigens. The purpose of this research was to clone E gene of dengue virus type 3 （Indonesia D3-1703 strain） into Saccharomyces cerevisiae expression vector pYES2/CT. The cloning method used was the in vitro ligation protocol. First, the cDNA from dengue virus type 3 strain （D3-1703） was generated. Then the polymerase chain reaction （PCR） amplification product of E gene cassette from this cDNA was obtained. The E gene cassette was ligated into linearized pYES2/CT resulting a recombinant vector named pYES2/CT-E. The cloned E gene was verified by restriction enzyme digestion and PCR. Sequencing analysis at its 5＇ end showed that the E gene was inserted at the right open reading frame. In conclusion, the results showed that for the first time the E gene originated from an Indonesian dengue virus type 3 strain was successfully cloned within the yeast expression vector pYES2/CT. In the future, this clone could be expressed and provided as materials for dengue vaccine and diagnostic kit, specific for Indonesian dengue virus strain.

Cloning and expression and purification of Hepatitis B e-antigen precursor in Escherichia coli

OBJECTIVE: To investigate the role of the 25 kD hepatitis B e antigen (HBeAg) precursor that only exist inside hepatocytes and study its effect on the pathopoiesis of hepatitis B and QIAGEN expression and purification system. METHODS: Hepatitis B virus (HBV) preC/C gene for the 25 kD HBeAg precursor was cloned into the expression vector pQE30 and the 25 kD HBeAg precursor was expressed in Escherichia coli (E. coli) and purified. Its antigenicity for 21 kD mature HBeAg was tested by western blot analysis. RESULTS: Cloned fragments in the expression vector were sequenced and verified to be homogeneous with that of HBV (ayw subtype). Expression of the HBeAg precursor in E. coli under the transcriptional regulation of T5 promoter yielded a soluble cytosolic protein with an apparent molecular mass of 25 kD. Recombinant HBeAg precursor exhibited identical potencies with 21 kD mature HBeAg that reacted with anti-HBeAg antibodies. The purification rate of the expressed HBeAg precursor was up to 89.6% and the yield of purified HBeAg precursor from this procedure was 2.4 mg/L. CONCLUSION: 25 kD HBeAg precursor exhibited biological activity and might play an important role in pathopoiesis of hepatitis B.

THE CLONING, SEQUENCING AND EXPRESSION OF THE LdMNPV POLYHEDRIN GENE

LdMNPV-NEFU isolate collected from the forestry farm of Northeast Forestry University was purified and the genomic DNA of LdMNPV was extracted. The LdMNPV polyhedrin gene was cloned by PCR. The results showed that the sequence was an open reading frame (ORF) of 735bp capable of encoding 245 amino acids. The polyhedrin gene sequences of the LdMNPV-NEFU isolate and a Canada strain, LdMNPV-G differed in 5 bases. The polyhedrin gene of the LdMNPV-NEFU isolate contained C, G, T, C and G at 54, 109,379, 508 and 701 sites from the start codon, but the LdMNPV-G isolate contained G, C, C, T and T at the corresponding sites respectively. The same amino acids were encoded by the two ORF sequences, with the exception that Asp and His are encoded by GAC on the polyhedrin gene sequence of the LdMNPV-NEFU isolate and by CAC in the LdMNPV-G isolate. The LdMNPV polyhedrin gene was expressed in E.coli BL21 (DE3) by the pT7-7 plasmid vector.

Construction and functional activity of a recombinant vector expressing rat glutamic acid decarboxylase 65

Objective Glutamic acid decarboxylase 2（GAD65） is a gamma-aminobutyric acid（GABA） synthetase.This study aimed to construct a recombinant lentivirus-rGAD65（rLV-rGAD65） vector containing the cDNA of rat GAD65（rGAD65） and assess its functional activity in vitro and in vivo.Methods cDNA of rGAD65 was amplified by RT-PCR and subcloned into the LV vector,forming the rLV-GFP-rGAD65 plasmid.The recombinant lentivirus particles（rLVrGAD65） were packaged by the LV Helper-Free System and the titer was measured.Primary rat lung fibroblasts were transfected with rLV-rGAD65.The expression of rGAD65 in fibroblasts was detected by immunocytochemistry and western blot and the level of GABA in the medium was assessed by high-performance liquid chromatograph（HPLC）.In vivo,rLV-rGAD65 was injected into the subthalamic nucleus（STN） of Sprague-Dawley rats using stereotaxic methods,and rGAD65 protein levels in the STN were assessed by immunohistochemistry and Western blot,while the GABA concentration in the substantia nigra pars reticulata（SNr） was assayed by HPLC.Results The sequence of rGAD65 cDNA was in accord with that in GenBank.The amino-acid sequence of rGAD65 had no mutations and the titer of rLVrGAD65 reached 6.8 × 108/mL.The efficiency of infection of fibroblasts was 80%,and the concentration of GABA in the medium was（48.14 ± 9.35） nmol/L.In vivo,rGAD65 expression was detected in the STN,and the concentration of GABA in the SNr increased from（5.95 ± 1.09） to（12.44 ± 3.79） nmol/g tissue.Conclusion The recombinant LVGFP-rGAD65 vector was successfully constructed.rLV-rGAD65-infected primary fibroblasts in vitro and the expressed rGAD65 catalyzed the formation of GABA from glutamic acid.In vivo,the concentration of GABA in the SNr was increased after rLV-rGAD65 injection into the STN.