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Results for “Recombinant expression”

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At least 721 records · Page 40Linked to original sources

PubMed1994

Recombinant capripoxvirus expressing the hemagglutinin protein gene of rinderpest virus: protection of cattle against rinderpest and lumpy skin disease viruses.

A cDNA clone containing the complete coding sequence of the hemagglutinin (H) protein gene of the RBOK vaccine strain of rinderpest virus, under the control of the vaccinia late promoter p11, was inserted by homologous recombination into the thymidine kinase gene of the KS-1 strain of capripoxvirus. The recombinant virus produced authentic H protein as judged by its electrophoretic mobility, transport to the cell surface of infected lamb testis cells, and reactivity with monoclonal antibodies specific for the H protein of rinderpest virus. The recombinant virus induced significant levels of rinderpest virus neutralizing antibodies in vaccinated cattle and protected them from clinical rinderpest after challenge with a lethal dose of a highly virulent heterologous strain of the virus. Protection was achieved using vaccine doses lower than those used with a similar recombinant expressing the fusion protein gene of rinderpest. The parental KS-1 virus is widely used as a vaccine against capripox viruses and so the rinderpest recombinant acts as a dual vaccine to protect cattle against both rinderpest and lumpy skin disease.

Animals↗

PubMed1994

An in vitro amplification approach for the expression of recombinant proteins in mammalian cells.

A method for the expression of recombinant DNA products in mammalian cells based on in vitro amplification of gene units is described. Gene cassettes containing either a selectable marker or the gene of interest are mixed at different molar ratios, and linear polymers are formed using forced head-to-tail ligation. After introduction of the polymers into mammalian cells, transformants with various amounts of the amplified gene unit are obtained. For a first characterization of the system, the gene coding for chloramphenicol acetyltransferase (CAT) has been used to produce polymers containing a single neomycin-resistance gene ligated to different numbers of CAT gene units and used for transfection into HeLa cells. All isolated G418 (gentamycin)-resistant cell transformants which received in vitro amplified DNA were found to express high levels of CAT activity in a stable manner. Southern-blot analysis of individual clones revealed multiple copies of the gene integrated head-to-tail in the genome. This system allowed us to express the gene coding for human prepro-endothelin-1 in A617 human vascular-smooth-muscle cells. The recombinant protein was shown to be correctly processed and biologically active endothelin-1.

Base Sequence↗

PubMed1992

Identification of the murine cytomegalovirus glycoprotein B gene and its expression by recombinant vaccinia virus.

The gene encoding glycoprotein B (gB) of murine cytomegalovirus (MCMV) strain Smith was identified, sequenced, and expressed by recombinant vaccinia virus. The gB gene was found adjacent to the polymerase gene, as it is in the genome of human cytomegalovirus (HCMV). The open reading frame consists of 2,784 nucleotides capable of encoding a protein of 928 amino acids. Comparison with gB homologs of other herpesviruses revealed a high degree of homology. The similarity between the MCMV gB and the HCMV gB is most prominent, since 45% of the amino acids are identical. In addition, all cysteine residues are at homologous positions, indicating a similar tertiary structure of the two proteins. In contrast to HCMV, the MCMV gB mRNA is a true late transcript. A recombinant vaccinia virus expressing the MCMV gB gene has been constructed (Vac-gB). Antibodies raised against the Vac-gB recombinant precipitated proteins of 130, 105, and 52 kDa from MCMV-infected cells. The identity of the MCMV gB with the major envelope glycoprotein of MCMV described by Loh et al. was shown (L. C. Loh, N. Balachandran, and L. F. Qualtiere, Virology 166:206-216, 1988). Immunization of mice with the Vac-gB recombinant gave rise to neutralizing antibodies.

Amino Acid Sequence↗

PubMed1991

Cell surface expression of herpes simplex virus type 1 glycoprotein H in recombinant baculovirus-infected cells.

DNA encoding the complete sequence for the herpes simplex virus type 1 (HSV-1) glycoprotein H (gH) was inserted into a baculovirus transfer vector under control of the baculovirus polyhedrin gene promoter. After co-transfection with wild-type baculovirus DNA, recombinants expressing gH were isolated by plaque purification. The baculovirus-expressed HSV-1 gH represented a significant portion of total cellular protein and was several hundred fold more abundant than gH in HSV-1-infected Vero cells. The expressed gH appeared to be glycosylated, since it was similar in size to wild-type HSV-1 gH, was susceptible to both tunicamycin and endoglycosidase-H treatment, and was labeled by [3H]mannose. In contrast to previous reports of gH expressed in mammalian cells, the baculovirus recombinant-expressed gH was abundant on the cell surface as judged by indirect immunofluorescence. To our knowledge, this is the first report of expressed HSV-1 gH being transported to the cell surface in the absence of other HSV-1 gene products and the first report of expressed gH with an apparent molecular weight similar to authentic HSV-1 gH.

Animals↗

PubMed1993

Mucosal immunity and protection after intranasal immunization with recombinant adenovirus expressing herpes simplex virus glycoprotein B.

A recombinant adenovirus (Ad) expressing glycoprotein B (gB) of herpes simplex virus (HSV) type 1 (AdgB8) was evaluated as a mucosal vaccine candidate. When administered intranasally (inl) to C57B1/6 mice, AdgB8 induced levels of serum anti-HSV gB IgG antibodies similar to those of mice immunized intraperitoneally (ip), which neutralized both HSV-1 and -2. Mice immunized inl with AdgB8 produced secretory IgA specific for HSV gB, but mice immunized ip did not. Splenic anti-HSV cytotoxic T lymphocytes (CTL) were observed after inl and ip immunization; however, there was a time-dependent decrease in the anti-HSV CTL activity from spleens of inl immunized mice. Anti-HSV CTL were also present in the mediastinal lymph nodes after inl but not ip AdgB8 immunization. Furthermore, mice immunized inl with AdgB8 were protected against heterologous inl challenge with HSV-2, and this protection lasted longer than in ip-immunized mice. These results indicate that mucosal immunization with a recombinant adenovirus can induce mucosal and systemic immune responses and provide long-term protection from mucosally or sexually transmitted viruses.

Administration, Intranasal↗

PubMed2006

[Construction of recombinant eukaryotic expression plasmid of murine chemokine MIP-1alpha and coimmunization with HSV-II DNA vaccine].

AIM: To construct the recombinant eukaryotic expression plasmid of murine macrophage inflammatory protein-1alpha (MIP-1alpha) and investigate the effect of MIP-1alpha as an adjuvant on immune response induced by herpes simplex virus type II glycoprotein D (HSV-II gD) DNA vaccine. METHODS: Using total RNA from RAW264.7 cells stimulated with LPS, the whole code sequence of murine MIP-1alpha was amplified by RT-PCR and inserted into pcDNA3 at Hind III/Xba I restriction sites. The recombinant eukaryotic expression plasmid Pm was transiently expressed in COS-7 cells and its specificity was demonstrated by RT-PCR and Boyden chemotaxis chamber assay. BALB/c mice were immunized with gD DNA vaccine and/or MIP-1alpha, and the effect of MIP-1alpha on gD DNA vaccine was evaluated by detecting anti-HSV-II antibody, antigen-specific lymphoproliferative responses, and examining survival rates after mice were challenged intravaginally with HSV-II. RESULTS: The recombinant eukaryotic expression plasmid of murine MIP-1alpha was constructed, and it was revealed that immune responses of HSV-II gD DNA vaccine were enhanced by coimmunization with MIP-1alpha. CONCLUSION: The murine MIP-1alpha can be used as an adjuvant of HSV-II gD DNA vaccine.

Animals↗

PubMed2003

Antisense oligodeoxynucleotide inhibits expression of recombinant porcine follicle-stimulating hormone receptor.

Follicle-stimulating hormone (FSH) regulates folliculogenesis in the ovary and spermatogenesis in the testis via specific, high affinity membrane-bound receptors (FSHR). To assess the role of FSHR gene expression in regulating expression of FSHR protein in the plasma membrane, the effects of a porcine FSHR cDNA antisense oligodeoxynucleotide (ODN) on FSHR mRNA levels and (125)I-FSH binding were determined in Chinese hamster ovary cells stably expressing recombinant porcine FSHR (pFSHR-CHO cells). An 18-mer phosphorothioated antisense ODN corresponding to the region surrounding the translation initiation codon of the porcine FSHR cDNA was synthesized. An 18-mer phosphorothioated nonsense sequence of identical nucleotide composition was synthesized for use as a control. pFSHR-CHO cells were cultured in the absence or presence of 1-20 microM antisense or nonsense ODN for 24 hr and then assayed for porcine FSHR mRNA, using quantitative reverse transcription and competitive polymerase chain reaction, and for (125)I-FSH binding activity. Treatment with 10 microM antisense ODN caused a paradoxical increase in porcine FSHR mRNA. Nonsense ODN had no effect on porcine FSHR mRNA. Antisense, but not nonsense, ODN (10 microM ) inhibited membrane binding of (125)I-FSH by 13.6 +/- 0.8% (mean +/- SEM, n = 3, P < 0.05) in 24 hr. Treatment of cells with antisense ODN (10 microM) for 48 hr resulted in a 76 +/- 1.5% (P < 0.05) inhibition of (125)I-FSH binding. These results indicate that an FSHR antisense ODN effectively inhibits porcine FSHR synthesis and inhibition of receptor synthesis causes a decrease in functional membrane-bound FSHR.

Animals↗

PubMed1997

Molecular pathogenesis of type I congenital plasminogen deficiency: expression of recombinant human mutant plasminogens in mammalian cells.

We previously reported the genetic abnormality in a Japanese family with type I congenital plasminogen deficiency caused by a Ser572 to Pro572 mutation. To characterize the molecular pathogenesis of the disease in this family, we expressed recombinant human wild-type and mutant (rS572P) plasminogens in COS-1 cells. Activation-resistant wild-type and mutant plasminogen stable transfectants in CHO-K1 cells also were established. Transient transfection and metabolic labeling experiments followed by immunoprecipitation analysis showed that the mutant plasminogen was secreted from COS-1 cells in reduced amounts, compared with the wild type. Endo H digestion of the wild-type and mutant plasminogen showed no shift in their migrations on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, indicating that both contain complex type oligosaccharide structures and could therefore be secreted. Furthermore, the secretion of activation-resistant mutant plasminogen was significantly reduced. Pulse-chase experiments and Northern blot analysis showed that the impaired secretion of the mutant plasminogen was the consequence of the accumulation of the mutant protein inside the cells but not of reduced plasminogen mRNA. Immunocytochemical staining of stable transfectants also revealed that CHO-K1 cells expressing the activation-resistant mutant plasminogen stained mainly in the perinuclear area, suggesting delayed processing of the mutant protein in the intracellular transport pathway. We conclude that the impaired secretion of mutant plasminogen, due to intracellular accumulation, is the molecular pathogenesis of type I congenital plasminogen deficiency caused by a Ser572 to Pro572 mutation.

Animals↗

PubMed2005

Improvements to the throughput of recombinant protein expression in the baculovirus/insect cell system.

Recombinant baculoviruses have proved to be a very useful means to express many proteins over the last 20 years. Since their introduction, there have been a number of significant improvements that have simplified and speeded up the construction of baculoviruses. One of the most commonly used methods relies upon recombination with the baculovirus genome maintained in Escherichia coli. In this paper, we report the conversion of nearly all the steps in this process including the expression testing and purification to a multi-well plate format. This enables a significant increase in the number of constructs that can be processed in a shorter period of time and an order of magnitude increase in the number of expression conditions that can be analysed. A key step in our process is that the transfection is done in suspension rather than adherent cells, which gives a much higher virus titre than in the standard methods.

Animals↗

PubMed1995

Construction and use of a nontoxigenic strain of Pseudomonas aeruginosa for the production of recombinant exotoxin A.

To express recombinant forms of Pseudomonas aeruginosa exotoxin A in high yield, we have developed a nontoxigenic strain of P. aeruginosa derived from the hypertoxigenic strain PA103. The nontoxigenic strain, designated PA103A, was produced by the excision marker rescue technique to replace the toxA structural gene in PA103 with an insertionally inactivated toxA gene. The PA103A strain (ToxA-) was used subsequently as the host strain for the expression and production of several recombinant versions of exotoxin A, and the results were compared with exotoxin A production in other P. aeruginosa and Escherichia coli strains. Use of the PA103A strain transformed with the high-copy-number pRO1614 plasmid bearing various toxA alleles resulted in final purification yields of exotoxin A averaging 23 mg/liter of culture. By comparison, exotoxin A production in other expression systems and host strains yields approximately 1/4 to 1/10 as much toxin.

ADP Ribose Transferases↗

PubMed1996

Mutants of Streptomyces roseosporus that express enhanced recombination within partially homologous genes.

Streptomyces roseosporus mutants that express enhanced recombination between partially homologous (homeologous) sequences were isolated by selection for recombination between the bacteriophage phi C31 derivative KC570 containing the Streptomyces coelicolor glucose kinase (glk) gene and the S. roseosporus chromosome. The frequencies of homeologous recombination in the ehr mutants were determined by measuring the chromosomal insertion frequencies of plasmids containing S. coelicolor glnA or whiG genes. S. roseosporus ehr mutants showed 10(2)- to 10(4)-fold increases in homeologous recombination relative to Ehr+ strains, but no increase in homologous recombination. Southern hybridization analysis revealed single unique sites for the insertion of each of the plasmids, and the crossovers occurred in frame and in proper translational register, yielding functional chimeric glnA and whiG genes.

Amino Acid Sequence↗

PubMed1994

Phenotypic characterization of insertion mutants of the human immunodeficiency virus type 1 Gag precursor expressed in recombinant baculovirus-infected cells.

A panel of 28 insertion mutants of the human immunodeficiency virus type 1 (HIV-1) Gag precursor (Pr55Gag) was constructed by linker-insertion mutagenesis and expressed in recombinant baculovirus-infected insect cells. One set of 14 mutants carried the normal N-myristylation signal; the other set constituted their non-N-myristylated counterparts. The mutants were characterized with respect to (i) assembly and extracellular release of membrane-enveloped budding Gag particles, (ii) intracellular assembly and nuclear transport of Gag cores, (iii) specific processing of Pr55Gag by HIV-1 protease in vivo, and (iv) binding of Pr55Gag to an HIV-1 genomic RNA probe in Northwestern blotting. Insertions within the region between amino acid residues 209 and 334 in the CA domain appeared to be the most detrimental to Gag particle assembly and release of Gag into the external medium, whereas a narrower window, between residues 209 and 241, was found to be critical for secretion of soluble Pr55Gag. Differences in Pr55Gag processing in vivo and RNA binding in vitro between N-myristylated and non-N-myristylated Gag mutants suggested a major conformational role for the myristylated N terminus of Gag precursor. In coinfection experiments using wild-type Gag- and mutant Gag-expressing recombinants, a transdominant negative effect on Gag particle assembly and release was observed for insertions located in two separate domains, the matrix and nucleocapsid.

Amino Acid Sequence↗

PubMed1998

Efficacy of multiple administrations of a recombinant adenovirus expressing wild-type p53 in an immune-competent mouse tumor model.

Infection of Renca cells in vitro with a recombinant adenovirus expressing a marker gene beta-galactosidase resulted in high level of the transgene expression. Renca tumors grown in Balb/C mice were also infectable with this recombinant adenovirus. The transgene expression in the tumors lasted for about 7 days, however, administration of another dose of Ad-beta gal, on day 7 produced beta-galactosidase expression. To investigate the effect of antibodies to adenovirus, animals were injected with multiple doses of adenovirus to produce neutralizing antibodies. To these animals Renca cells were injected and tumors formed. Interestingly, when Ad beta-gal was administered into these tumors, a high level of transgene expression was still observed. We next explored the utility of a recombinant adenovirus expressing p53 (AdWTp53) in the Renca tumor model. Renca cells when exposed to an adenovirus expressing p53 (AdWTp53) produced a high level of p53 protein, a p53-inducible gene p21/WAF1/Cip1 and underwent apoptosis. A single injection of AdWTp53 (10(9) plaque forming units) resulted in significant inhibition of tumor growth. However, multiple administrations (four doses of 2.5 x 10(8) plaque forming units) of AdWTp53 were needed for tumor cures. Mixing uninfected and AdWTp53-infected cells showed a bystander effect of AdWTp53-infected Renca cells. Based on these results we believe that an appropriate dose scheduling of AdWTp53 can be efficacious for cancer gene therapy in immune-competent tumor-bearing animals.

Adenoviridae↗

PubMed2007

Quantitative analysis of Nipah virus proteins released as virus-like particles reveals central role for the matrix protein.

BACKGROUND: Nipah virus (NiV) is an emerging paramyxovirus distinguished by its ability to cause fatal disease in both animal and human hosts. Together with Hendra virus (HeV), they comprise the genus Henipavirus in the Paramyxoviridae family. NiV and HeV are also restricted to Biosafety Level-4 containment and this has hampered progress towards examining details of their replication and morphogenesis. Here, we have established recombinant expression systems to study NiV particle assembly and budding through the formation of virus-like particles (VLPs). RESULTS: When expressed by recombinant Modified Vaccinia virus Ankara (rMVA) or plasmid transfection, individual NiV matrix (M), fusion (F) and attachment (G) proteins were all released into culture supernatants in a membrane-associated state as determined by sucrose density gradient flotation and immunoprecipitation. However, co-expression of F and G along with M revealed a shift in their distribution across the gradient, indicating association with M in VLPs. Protein release was also altered depending on the context of viral proteins being expressed, with F, G and nucleocapsid (N) protein reducing M release, and N release dependent on the co-expression of M. Immunoelectron microscopy and density analysis revealed VLPs that were similar to authentic virus. Differences in the budding dynamics of NiV proteins were also noted between rMVA and plasmid based strategies, suggesting that over-expression by poxvirus may not be appropriate for studying the details of recombinant virus particle assembly and release. CONCLUSION: Taken together, the results indicate that NiV M, F, and G each possess some ability to bud from expressing cells, and that co-expression of these viral proteins results in a more organized budding process with M playing a central role. These findings will aid our understanding of paramyxovirus particle assembly in general and could help facilitate the development of a novel vaccine approach for henipaviruses.

Animals↗

PubMed1990

Intracellular processing and immunogenicity of the envelope proteins of human T-cell leukemia virus type I that are expressed from recombinant vaccinia viruses.

Two types of recombinant vaccinia viruses (VVs) expressing the env gene of the human T-cell leukemia virus type I (HTLV-I) were reported previously. One recombinant VV, WR-proenv1, synthesized the authentic env protein. In the other recombinant VV, WR-env17, the env gene was inserted within the signal sequence of the VV hemagglutinin (HA) gene, so that the reading frame for the env gene was in phase with that for the HA gene. Comparative studies were performed on the mode of expression and processing of the env proteins in relation to their immunogenicity. In WR-env17-infected cells, translation was initiated exclusively from the initiation methionine of the HA to produce nascently the chimeric env protein, including the altered HA signal peptide. Both this altered HA signal peptide and the internalized env signal peptide functioned as insertion signals for the endoplasmic reticulum. Although about half of the nascent chimeric protein was cleaved at the carboxyl terminus of the internalized env signal peptide to produce the authentic env protein, the other half was cleaved at the carboxyl terminus of the altered HA signal peptide alone to synthesize the chimeric protein. These events led to a less efficient transport of the env protein produced by WR-env17 from the rough endoplasmic reticulum to the Golgi apparatus than that of the authentic env protein synthesized by WR-proenv1. The efficiency of the processing and transport of the env protein affected the immunogenicity of these two recombinant VVs.

Animals↗

PubMed2003

Local immunotherapy of spontaneous feline fibrosarcomas using recombinant poxviruses expressing interleukin 2 (IL2).

We tested the canarypox virus vector ALVAC and the genetically attenuated vaccinia virus vector NYVAC as vehicles for achieving local immunomodulation in domestic animals bearing spontaneous tumours. Following intratumoral administration of ALVAC-, or NYVAC-luciferase in dogs with melanoma, it was demonstrated that viral recombinants remained localized along the needle track, with no virus detectable in the periphery of the tumour. Given these distribution characteristics and their well-documented safety profile, ALVAC- or NYVAC-based recombinants expressing feline or human IL2, respectively, were administered to domestic cats, in order to prevent the recurrence of spontaneous fibrosarcomas. In the absence of immunotherapy, tumour recurrence was observed in 61% of animals within a 12-month follow-up period after treatment with surgery and iridium-based radiotherapy. In contrast, only 39 and 28% of cats receiving either NYVAC-human IL2 or ALVAC-feline IL2, respectively, exhibited tumour recurrences. Based on such results, and in the context of ongoing clinical studies conducted in humans, we discuss the utilization of ALVAC- or NYVAC-based recombinants as viable therapeutic modalities for local immunotherapy or therapeutic vaccination against cancer, both in humans and companion animals.

Animals↗

PubMed2004

[Construction of replication-deficient recombinant adenovirus expressing gag-polDelta and gp140TM genes of human immunodeficiency virus in mice].

BACKGROUND: Construction of replication-deficient recombinant adenovirus expressing gag-pol and env genes of human immunodeficiency virus (HIV) in mice. METHODS: gag-polDelta and gp140TM genes were cloned into shuttle vector pAdTrack-CMV respectively, and then the plasmids containing gag-polDelta or gp140TM gene were cotransformed with the backbone of adenovirus into E.coli BJ5183. Transfections of the recombinants were performed to obtain recombinant adenoviruses. Its immunogenicity was evaluated by testing antibody levels of mice primed with DNA vaccines and boosted with recombinant adenoviruses. RESULTS: The replication-deficient recombinant adenovirus could express Gp140TM, Gag P55 and P24 proteins correctly. The mice primed with DNA vaccines and boosted with recombinant adenoviruses elicited high titer of HIV-1-specific antibody compared with that inoculated with DNA vaccines only. CONCLUSION: Replication-deficient recombinant adenovirus expressing gag-polDelta and gp140TM can elicit high titer HIV-1-specific antibodies.

AIDS Vaccines↗

PubMed2003

[Construction and expression of recombinant antibody/granzyme B containing truncated translocating peptide].

AIM: To construct an eukaryotic expression vector for recombinant antibody/granzyme B gene containing truncated translocating peptide and express it in HER-2(+) SKBR-3 cells and HER-2(-) Hela cells. METHODS: PCR amplication was used to obtain recombinant DNA encoding antibody/granzyme B containing truncated translocating peptide DNA, and then the DNA fragment was cloned into eukaryotic expression vector pCMV-e23sFv-PE40. After being transfected into SKBR-3 cells and Hela cells, the expression of target gene and its effect on cellular morphology were detected by immunocytochemical staining. RESULTS: The eukaryotic expression vector encoding recombinant antibody/granzyme B containing truncated translocating peptide was successfully constructed. e23sFv-FSD-GrB protein was expressed in most of Hela cells and had no effect on Hela cells, but the transfected SKBR-3 cells which also express e23sFv-FSD-GrB protein exhibited condensed nucleus and cytoplasm. CONCLUSION: The construction of eukaryotic expression vector of recombinant antibody/granzyme B gene containing truncated translocating peptide lays the foundation for further determination of minimal fragment responsible for translocation.

ADP Ribose Transferases↗