Project description:Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) is the best-studied baculovirus and most commonly used virus vector for baculovirus expression vector systems. The effect of AcMNPV infection on host cells is incompletely understood. A microarray based on Spodoptera frugiperda ESTs was used to investigate the impact of AcMNPV on host gene expression in cultured S. frugiperda, Sf21 cells. Most host genes were down-regulated over the time course of infection, although a small number were up-regulated. The most highly up-regulated genes encoded heat shock protein 70s and several poorly characterized proteins. Regulated genes with the highest score identified by functional annotation clustering included primarily products required for protein expression and trafficking in the ER and golgi. All were significantly down-regulated by approximately 12h post-infection. Microarray data were validated by qRT-PCR. This study provides the first comprehensive host transcriptome overview of Sf21 cells during AcMNPV infection.
Project description:Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) is the best-studied baculovirus and most commonly used virus vector for baculovirus expression vector systems. The effect of AcMNPV infection on host cells is incompletely understood. A microarray based on Spodoptera frugiperda ESTs was used to investigate the impact of AcMNPV on host gene expression in cultured S. frugiperda, Sf21 cells. Most host genes were down-regulated over the time course of infection, although a small number were up-regulated. The most highly up-regulated genes encoded heat shock protein 70s and several poorly characterized proteins. Regulated genes with the highest score identified by functional annotation clustering included primarily products required for protein expression and trafficking in the ER and golgi. All were significantly down-regulated by approximately 12h post-infection. Microarray data were validated by qRT-PCR. This study provides the first comprehensive host transcriptome overview of Sf21 cells during AcMNPV infection. Host gene expression of the Sf21 cells was measured in AcMNPV mock-infected Sf21cells as well as AcMNPV-infected Sf21 cells at 6, 12, and 24 hours post infection (hpi). Four independent experiments were performed at each time (6, 12, and 24 hpi) using different donors for each experiment. Only two 24 hour sample data sets were used in the final analysis as two did not meet QC criteria.
Project description:Baculovirus expression systems have been widely used to produce recombinant mammalian proteins owing to the lack of viral replication in vertebrates. Although several lines of evidence have demonstrated impacts of baculovirus infection in mammalian hosts, genome-wide effects have not been fully elucidated. Here, we provide comparative transcriptome profiles of baculovirus and host-immune response genes in recombinant baculovirus-infected mammalian and insect cells. Specifically, to decipher the impacts of baculovirus infection in mammalian cells, we conducted total RNA-seq on human 293 cells and insect Sf9 cells infected with recombinant baculovirus. We found that baculovirus genes were rarely expressed under the control of baculoviral promoters in 293 cells. Although some baculovirus early genes, such as PE38 and IE-01, showed limited expression in 293 cells, baculoviral late genes were mostly silent. We also found modest induction of a small number of mammalian immune response genes associated with Toll-like receptors, cytokine signaling, and complement in baculovirus-infected 293 cells. These comprehensive transcriptome data will contribute to improving recombinant baculovirus as tools for gene delivery, gene therapy, and vaccine development.
Project description:The human Adeno-Associated Virus serotype 2 (WT AAV2) is a common non-pathological virus and its recombinant form (rAAV) is widely used as gene therapy vector. However, it has been shown that WT AAV2 and recombinant AAV display significantly different characteristics, especially regarding infection rate, with a near perfect infectivity and better encapsidation rate of WT AAV2. Even though rAAVs are routinely produced in the Baculovirus/Sf9 cell system, WT AAV2 has never been produced in this context. To understand the infectivity and encapsidation rate differences between WT AAV2 and rAAV, we tried to produce WT AAV2 in baculovirus/Sf9 cells system hypothesizing that the WT AAV2 may be considered as a normal recombinant AAV transgene. Through our attempts to produce WT AAV2 in Baculovirus/Sf9, we found that WT AAV2 p5 promoter, which controls the expression of large Rep proteins in mammalian cells, was active in this system. p5 promoter activity in the baculovirus/Sf9 cell system led to the expression of Rep78 that finally excises WT AAV2 genome from the baculovirus genome during the earliest phase of baculovirus stock production. The p5 promoter expression kinetics and the specific strand RNA-Seq analysis of the WT AAV2, rAAV Rep2/Cap2 cassettes in the baculovirus context was performed. We demonstrate that the WT AAV2 native promoters, p5, p19 and p40 are all active and lead to the expression of different proteins and peptides. In addition, this study demonstrates that the baculovirus brings at least some of the helper functions needed in the AAV replication/life cycle.
Project description:MicroRNAs (miRNAs) as small non-coding RNAs play important roles in many biological processes such as development, cell signalling and immune response. Studies also suggest that miRNAs are important in host–virus interactions where the host limits virus infection by differentially expressing miRNAs that target essential viral genes. Here, we identified conserved and new miRNAs from Spodoptera frugiperda cells (Sf9) using a combination of deep sequencing and bioinformatics as well as experimental approaches. S. frugiperda miRNAs share common features of miRNAs in other organisms, such as uracil (U) at the 59 end of miRNA. The 59 ends of the miRNAs were more conserved than the 39 ends, revealing evolutionary protection of the seed region in miRNAs. The predominant miRNAs were found to be conserved among arthropods. The majority of homologous miRNAs were found in Bombyx mori, with 76 of the 90 identified miRNAs. We found that seed shifting and arm switching have happened in this insect’s miRNAs. Expression levels of the majority of miRNAs changed following baculovirus infection. Results revealed that baculovirus infection mainly led to an overall suppression of cellular miRNAs. We found four different genes being regulated by sfr-miR-184 at the post-transcriptional level. The data presented here further support conservation of miRNAs in insects and other organisms. In addition, the results reveal a differential expression of host miRNAs upon baculovirus infection, suggesting their potential roles in host–virus interactions. Seed shifting and arm switching happened during evolution of miRNAs in different insects and caused miRNA diversification, which led to changes in the target repository of miRNAs. Identification of miRNA and other small non coding RNA in NPV infected Sf9 cells
Project description:MicroRNAs (miRNAs) as small non-coding RNAs play important roles in many biological processes such as development, cell signalling and immune response. Studies also suggest that miRNAs are important in host–virus interactions where the host limits virus infection by differentially expressing miRNAs that target essential viral genes. Here, we identified conserved and new miRNAs from Spodoptera frugiperda cells (Sf9) using a combination of deep sequencing and bioinformatics as well as experimental approaches. S. frugiperda miRNAs share common features of miRNAs in other organisms, such as uracil (U) at the 59 end of miRNA. The 59 ends of the miRNAs were more conserved than the 39 ends, revealing evolutionary protection of the seed region in miRNAs. The predominant miRNAs were found to be conserved among arthropods. The majority of homologous miRNAs were found in Bombyx mori, with 76 of the 90 identified miRNAs. We found that seed shifting and arm switching have happened in this insect’s miRNAs. Expression levels of the majority of miRNAs changed following baculovirus infection. Results revealed that baculovirus infection mainly led to an overall suppression of cellular miRNAs. We found four different genes being regulated by sfr-miR-184 at the post-transcriptional level. The data presented here further support conservation of miRNAs in insects and other organisms. In addition, the results reveal a differential expression of host miRNAs upon baculovirus infection, suggesting their potential roles in host–virus interactions. Seed shifting and arm switching happened during evolution of miRNAs in different insects and caused miRNA diversification, which led to changes in the target repository of miRNAs.
Project description:Recombinant baculoviral vectors efficiently transduce several types of cells in the brain. To characterize host responses to viral challenge, thus verifying the suitability of using the virus for the development of gene therapy strategies in the central nervous system, we used cDNA microarray technology to examine in vitro and in vivo global cellular gene expression profiles after viral transduction. We demonstrated that the transduction induced host antiviral responses as a major reaction in all three types of samples profiled, including the rat brain, cultured human astrocytes and human neuronal cells. The related genes were mainly those associated with innate immunity. Several genes of the major histocompatibility complex molecules, an important component of the host adaptive immunity to exogenous pathogens, were up-regulated in the rat brain and human astrocytes, but not in neuronal cells. We also observed that genes related to cell death and apoptosis were up-regulated and genes related cell cycle regulation were down-regulated in neuronal cells, but not obviously affected in astrocytes. These findings should be useful in understating the molecular basis for neural cell response to baculoviral transduction and guiding rational applications of baculoviral vectors in the central nervous systems Experiment Overall Design: CMV-Luc baculovirus with a luciferase reporter gene under the control of hCMV promoter and CMV-GFP baculovirus with a gene encoding for a green fluorescence protein were constructed as described previously (Wang et al., 2006). Both vectors were used to confirm baculoviral transduction. Our pilot test, as well as previous studies (Stilwell and Samulski, 2003; Zhao et al., 2005), demonstrated no detectable difference between viral vectors with and without a reporter gene in affecting global gene expression profiles. Thus, CMV-Luc baculovirus was used throughout microarray experiments. Experiment Overall Design: Recombinant baculovirus vectors were produced and propagated in Spodoptera frugiperda (Sf9) insect cells according to the manual of the Bac-to-Bac baculovirus expression system (Invitrogen). Sf9 insect cells pre-adapted to Sf-900 II serum-free medium were purchased from Invitrogen (Carlsband, CA) and grown in spinner flasks at 27.5oC. Budded viruses in the insect cell culture medium were collected and filtered through a 0.45-μm pore size filter (Minipore, Bedford, MA, USA) to remove any contamination, and concentrated by ultracentrifugation at 28,000g for 60 min. Viral pellets were re-suspended in appropriate volumes of 0.1 M phosphate-buffered saline (PBS) and their infectious titers (plaque-forming units, pfu) were determined by plaque assay on Sf9 cells. Experiment Overall Design: For in vitro study, normal human astrocytes (Lonza, Basel, Switzerland) were cultured in Astrocyte Basal Medium (ABM) supplemented with the AGM SingleQuots. Cells were maintained according to manufacturerâs instructions. Human neuronal cells, transdifferentiated from human Cord Blood Stem Cell culture, were obtained from Celprogen (San Pedro, CA). The cells were cultured on flasks coated with neuronal expansion matrix in human neuronal expansion complete media and maintained according to the manufacturerâs instructions. Cells were transduced with baculoviruses in Optimem (Invitrogen) at an MOI of 50 and incubated at 37°C for 1 h. After the incubation, the medium containing the viruses was replaced by fresh growth medium, and the cells were collected 48 hours later for analysis.
Project description:Recombinant baculoviral vectors efficiently transduce several types of cells in the brain. To characterize host responses to viral challenge, thus verifying the suitability of using the virus for the development of gene therapy strategies in the central nervous system, we used cDNA microarray technology to examine in vitro and in vivo global cellular gene expression profiles after viral transduction. We demonstrated that the transduction induced host antiviral responses as a major reaction in all three types of samples profiled, including the rat brain, cultured human astrocytes and human neuronal cells. The related genes were mainly those associated with innate immunity. Several genes of the major histocompatibility complex molecules, an important component of the host adaptive immunity to exogenous pathogens, were up-regulated in the rat brain and human astrocytes, but not in neuronal cells. We also observed that genes related to cell death and apoptosis were up-regulated and genes related cell cycle regulation were down-regulated in neuronal cells, but not obviously affected in astrocytes. These findings should be useful in understating the molecular basis for neural cell response to baculoviral transduction and guiding rational applications of baculoviral vectors in the central nervous systems Experiment Overall Design: CMV-Luc baculovirus with a luciferase reporter gene under the control of hCMV promoter and CMV-GFP baculovirus with a gene encoding for a green fluorescence protein were constructed as described previously (Wang et al., 2006). Both vectors were used to confirm baculoviral transduction. Our pilot test, as well as previous studies (Stilwell and Samulski, 2003; Zhao et al., 2005), demonstrated no detectable difference between viral vectors with and without a reporter gene in affecting global gene expression profiles. Thus, CMV-Luc baculovirus was used throughout microarray experiments. Experiment Overall Design: Recombinant baculovirus vectors were produced and propagated in Spodoptera frugiperda (Sf9) insect cells according to the manual of the Bac-to-Bac baculovirus expression system (Invitrogen). Sf9 insect cells pre-adapted to Sf-900 II serum-free medium were purchased from Invitrogen (Carlsband, CA) and grown in spinner flasks at 27.5oC. Budded viruses in the insect cell culture medium were collected and filtered through a 0.45-μm pore size filter (Minipore, Bedford, MA, USA) to remove any contamination, and concentrated by ultracentrifugation at 28,000g for 60 min. Viral pellets were re-suspended in appropriate volumes of 0.1 M phosphate-buffered saline (PBS) and their infectious titers (plaque-forming units, pfu) were determined by plaque assay on Sf9 cells. Experiment Overall Design: For in vitro study, normal human astrocytes (Lonza, Basel, Switzerland) were cultured in Astrocyte Basal Medium (ABM) supplemented with the AGM SingleQuots. Cells were maintained according to manufacturerâs instructions. Human neuronal cells, transdifferentiated from human Cord Blood Stem Cell culture, were obtained from Celprogen (San Pedro, CA). The cells were cultured on flasks coated with neuronal expansion matrix in human neuronal expansion complete media and maintained according to the manufacturerâs instructions. Cells were transduced with baculoviruses in Optimem (Invitrogen) at an MOI of 50 and incubated at 37°C for 1 h. After the incubation, the medium containing the viruses was replaced by fresh growth medium, and the cells were collected 48 hours later for analysis.