Project description:Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.
Project description:Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.
Project description:Noroviruses cause immense sporadic gastroenteritis outbreaks worldwide. Upcoming genotypes, which are divided based on VP1 sequence, further enhance this public thread regularly. Self-assembling properties of the human norovirus major capsid protein VP1 are crucial for using virus-like particles (VLPs) for vaccine development. However, there is no vaccine available yet. Here, VLPs from different variants produced in insect cells are characterized in detail using a set of biophysical and structural tools.
Project description:Purpose: Comparison of RNA-sequencing datasets obtained from exosomes of Nef-transfected and Mock-transfected HEK293T cells Methods: Assessment of RNA content of exosomes produced by Nef-transfected HEK293T cells and and Mock-transfected HEK293T cells Results: Differences in a set of microRNAs Conclusions: Nef-transfection induces changes in the microRNA content of exosomes
Project description:Purpose: Comparison of RNA-sequencing datasets obtained from exosomes of Nef-transfected and Mock-transfected HEK293T cells. Methods: Assessment of RNA content of exosomes produced by Nef-transfected HEK293T cells and and Mock-transfected HEK293T cells. Results: Differences in a set of mRNAs. Conclusions: Nef-transfection might induces changes in the mRNA content of exosomes.
Project description:With more than 130 clinical trials and eight approved gene therapy products, AAVs stand as one of the most popular vehicles to deliver therapeutic DNA in vivo. One critical quality attribute analyzed in AAV batches is the presence of residual DNA, as it could pose genotoxic risks or induce immune responses. Surprisingly, the presence of small cell‑derived RNAs, such as micro‑RNAs, has not been previously investigated. In this study, we examined the presence of miRNAs in purified AAV batches produced in mammalian or in insect cells. Our findings revealed that miRNAs were present in all batches, regardless of the production cell line or capsid serotype (2 and 8). Quantitative assays indicated that miRNAs were co‑purified with the rAAV particles in a proportion correlated with their abundance in the production cells. The level of residual miRNAs was reduced via an immunoaffinity chromatography purification process including a tangential flow filtration step or by RNase treatment, suggesting that most miRNA contaminants are likely non encapsidated into AAV particles. In summary, we demonstrate, for the first time, that miRNAs are co-purified with AAV particles. Further investigations are required to determine whether these miRNAs could interfere with the safety or efficacy of AAV-mediated gene therapy.
Project description:Entomopathogenic nematodes from the genus Steinernema are lethal insect parasites that quickly kill their insect hosts with the help of their symbiotic bacteria. Steinernema carpocapsae is one of the most studied entomopathogens due to its broad lethality to diverse insect species and its effective commercial use as a biological control agent for insect pests, as well as a genetic model for studying parasitism, pathogenesis, and symbiosis. In this study, we used long-reads from the Pacific Biosciences platform and BioNano Genomics Irys system to assemble the best genome of S. carpocapsae ALL strain to date, comprising 84.5 Mb in 16 scaffolds, with an N50 of 7.36Mb. The largest scaffold, with 20.9Mb, was identified as chromosome X based on sex-specific genome sequencing. The high level of contiguity allowed us to characterize gene density, repeat content, and GC content. RNA-seq data from 17 developmental stages, spanning from embryo to adult, were used to predict 30,957 gene models. Using this new genome, we performed a macrosyntenic analysis to Caenorhabditis elegans and Pristionchus pacificus and found S. carpocapsae’s chromosome X to be primarily orthologous to C. elegans’ and P. pacificus’ chromosome II and IV. We also investigated the expansion of protein families and gene expression differences between male and female stage nematodes. This new genome and more accurate set of annotations provide a foundation for new comparative genomic and gene expression studies within the Steinernema clade and across the Nematode phylum.
Project description:Soybean is a self-pollinating crop species that has relatively low nucleotide polymorphism rates compared to other crop plant species. Despite the appearance of a low intervarietal nucleotide polymorphism rate, a wide range of heritable phenotypic variation exists. There is even evidence for heritable phenotypic variation among individuals within some varieties. ‘Williams 82,’ the soybean variety used to produce the reference genome sequence, was derived from backcrossing a phytophthora root rot resistance locus from the donor parent ‘Kingwa’ into the recurrent parent ‘Williams.’ To explore the genetic basis of intravarietal variation, we investigated the nucleotide, structural and gene content variation of different Williams 82 individuals. Williams 82 individuals exhibited variation in the number and size of introgressed Kingwa loci. In these regions of genomic heterogeneity, the reference Williams 82 genome sequence consists of a mosaic of Williams and Kingwa haplotypes. Genomic structural variation between Williams and Kingwa was maintained between the Williams 82 individuals within the regions of heterogeneity. Additionally, the regions of heterogeneity exhibited gene content differences between Williams 82 individuals. Collectively, these findings show that genetic heterogeneity in Williams 82 primarily originated from the differential segregation of polymorphic chromosomal regions following the backcross and single-seed descent generations of the breeding process. We conclude that soybean haplotypes can possess a high rate of structural and gene content variation, and the impact of intravarietal genetic heterogeneity may be much greater than previously assumed. This detailed characterization will be useful for interpreting soybean genomic data sets and highlights important considerations for research communities that are utilizing or working towards developing a reference genome sequence. Soybean variety Williams 82 (Wm82) was derived from a Williams x Kingwa BC6F3 population. CGH was performed to detect regions of Kingwa genomic introgression in Wm82; Williams was hybridized as a common reference against Kingwa and four different Wm82 individuals. Two different Wm82 individuals (SGC and ISU) were also hybridized with one another. The soybean tiling array consists of 700k probes, spaced at approximately 1.1 kb intervals.