Jondavid de Jong

Autographa californica Multiple Nucleopolyhedrovirus me53 (ac140) Is a Nonessential Gene Required for Efficient Budded-Virus Production

ABSTRACT me53 is a highly conserved baculovirus gene found in all lepidopteran baculoviruses that have been fully sequenced to date. The putative ME53 protein contains a zinc finger domain and has been previously described as a major early transcript. We generated an me53-null bacmid (AcΔme53GFP), as well as a repair virus (AcRepME53:HA-GFP) carrying me53 with a C-terminal hemagglutinin (HA) tag, under the control of its native early and late promoter elements. Sf9 and BTI-Tn-5b1 cells transfected with AcΔme53GFP resulted in a 3-log reduction in budded-virus (BV) production compared to both the parental Autographa californica multiple nucleopolyhedrosis virus and the repair bacmids, demonstrating that although me53 is not essential for replication, replication is compromised in its absence. Our data also suggest that me53 does not affect DNA replication. Cell fractionation showed that ME53 is found in both the nucleus and the cytoplasm as early as 6 h postinfection. Deletion of the early transcriptional start site resulted in a 10- to 360-fold reduction of BV yield; however, deletion of the late promoter (ATAAG) resulted in a 160- to 1,000-fold reduction, suggesting that, in the context of BV production, ME53 is required both early and late in the infection cycle. Additional Western blot analysis of purified virions from the repair virus revealed that ME53:HA is associated with both BV and occlusion-derived virions. Together, these results indicate that me53, although not essential for viral replication, is required for efficient BV production.

Immediate-Early Protein ME53 Forms Foci and Colocalizes with GP64 and the Major Capsid Protein VP39 at the Cell Membranes of Autographa californica Multiple Nucleopolyhedrovirus-Infected Cells

ABSTRACT me53 is an immediate-early/late gene found in all lepidopteran baculoviruses sequenced to date. Deletion of me53 results in a greater-than-1,000-fold reduction in budded-virus production in tissue culture (J. de Jong, B. M. Arif, D. A. Theilmann, and P. J. Krell, J. Virol. 83:7440-7448, 2009). We investigated the localization of ME53 using an ME53 construct fused to green fluorescent protein (GFP). ME53:GFP adopted a primarily cytoplasmic distribution at early times postinfection and a primarily nuclear distribution at late times postinfection. Additionally, at late times ME53:GFP formed distinct foci at the cell periphery. These foci colocalized with the major envelope fusion protein GP64 and frequently with VP39 capsid protein, suggesting that these cell membrane regions may represent viral budding sites. Deletion of vp39 did not influence the distribution of ME53:GFP; however, deletion of gp64 abolished ME53:GFP foci at the cell periphery, implying an association between ME53 and GP64. Despite the association of ME53 and GP64, ME53 fractionated with the nucleocapsid only after budded-virus fractionation. Together these findings suggest that ME53 may be providing a scaffold that bridges the viral envelope and nucleocapsid.

Selection and Characterization of Autographa californica Multiple Nucleopolyhedrovirus DNA Polymerase Mutations

ABSTRACT Autographa californica multiple nucleopolyhedrovirus (AcMNPV) DNA polymerase (DNApol) is essential for viral DNA replication. AcMNPV mutants resistant to aphidicolin, a selective inhibitor of viral DNA replication, and abacavir, an efficacious nucleoside analogue with inhibitory activity against reverse transcriptase, were selected by the serial passage of the parental AcMNPV in the presence of increasing concentrations of aphidicolin or abacavir. These drug-resistant mutants had either a single (C543R) (aphidicolin) or a double (C543R and S611T) (abacavir) point mutation within conserved regions II and III. To confirm the role of these point mutations in AcMNPV DNA polymerase, a dnapol knockout virus was first generated, and several repair viruses were constructed by transposing the dnapol wild-type gene or ones containing a single or double point mutation into the polyhedrin locus of the dnapol knockout bacmid. The single C543R or double C543R/S611T mutation showed increased resistance to both aphidicolin and abacavir and, even in the absence of drug, decreased levels of virus and viral DNA replication compared to the wild-type repair virus. Surprisingly, the dnapol mutant repair viruses led to the generation of occlusion-derived viruses with mostly single and only a few multiple nucleocapsids in the ring zone and within polyhedra. Thus, these point mutations in AcMNPV DNA polymerase increased drug resistance, slightly compromised virus and viral DNA replication, and influenced the viral morphogenesis of occlusion-derived virus.

Rapid generation of fowl adenovirus 9 vectors

Fowl adenoviruses (FAdV) have the largest genomes of any fully sequenced adenovirus genome, and are widely considered as excellent platforms for vaccine development and gene therapy. As such, there is a strong need for stream-lined protocols/strategies for the generation of recombinant adenovirus genomes. Current genome engineering strategies rely upon plasmid based homologous recombination in Escherichia coli BJ5183. This process is time-consuming, involves multiple cloning steps, and low efficiency recombination. This report describes a novel system for the more rapid generation of recombinant fowl adenovirus genomes using the lambda Red recombinase system in E. coli DH10B. In this strategy, PCR based amplicons with around 50 nt long homologous arms, a unique SwaI site and a chloramphenicol resistance gene fragment (CAT cassette), are introduced into the FAdV-9 genome in a highly efficient and site-specific manner. To demonstrate the efficacy of this system we generated FAdV-9 ORF2, and FAdV-9 ORF11 deleted, CAT marked and unmarked FAdV-9 infectious clones (FAdmids), and replaced either ORF2 or ORF11, with an EGFP expression cassette or replaced ORF2 with an EGFP coding sequence via the unique SwaI sites, in approximately one month. All recombinant FAdmids expressed EGFP and were fully infectious in CH-SAH cells.

Nuclear Translocation Sequence and Region in Autographa californica Multiple Nucleopolyhedrovirus ME53 That Are Important for Optimal Baculovirus Production

ABSTRACT Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is in the family Baculoviridae, genus Alphabaculovirus. AcMNPV me53 is a highly conserved immediate early gene in all lepidopteran baculoviruses that have been sequenced and is transcribed up to late times postinfection. Although me53 is not essential for viral DNA synthesis, infectious budded virus (BV) production is greatly attenuated when it is deleted. ME53 associates with the nucleocapsid on both budded virus and occlusion-derived virus, but not with the virus envelope. ME53 colocalizes in plasma membrane foci with the envelope glycoprotein GP64 in a GP64-dependent manner. ME53 localizes in the cytoplasm early postinfection, and despite the lack of a reported nuclear localization signal (NLS), ME53 translocates to the nucleus at late times postinfection. To map determinants of ME53 that facilitate its nuclear translocation, recombinant AcMNPV bacmids containing a series of ME53 truncations, internal deletions, and peptides fused with hemagglutinin (HA) or green fluorescent protein (GFP) tags were constructed. Intracellular-localization studies identified residues within amino acids 109 to 137 at the N terminus of ME53 that acted as the nuclear translocation sequence (NTS), facilitating its nuclear transport at late times postinfection. The first 100 N-terminal amino acids and the last 50 C-terminal amino acids of ME53 are dispensable for high levels of budded virus production. The region within amino acids 101 to 398, which also contains the NTS, is critical for optimal levels of budded virus production. IMPORTANCE Baculovirus me53 is a conserved immediate early gene found in all sequenced lepidopteran alpha- and betabaculoviruses. We first identified residues within amino acids 109 to 137 at the N terminus that act as the ME53 nuclear translocation sequence (NTS) to facilitate its nuclear translocation and defined an internal region within amino acids 101 to 398, which includes the NTS, as being necessary for optimal budded virus production. Altogether, these results indicate a previously unidentified nuclear role that ME53 plays in virus replication.

AAV vector distribution in the mouse respiratory tract following four different methods of administration

BackgroundTargeted delivery of gene therapy vectors to the mouse respiratory tract is often performed via intranasal or intratracheal administration; however, there can be a great deal of variability between these methods, which could potentially influence experimental results. Improving the accuracy and precision of lung delivery will not only reduce the number of animals required to detect statistically significant differences, but may reduce the variability of studies from different laboratories.ResultsHere we evaluated three different methods of adeno-associated virus (AAV) vector administration to the respiratory tract in mice (intranasal, intubation, and intratracheal injection) and discuss the advantages, challenges, and shortcomings of each. We also present a modified-intranasal delivery technique that is superior to passive administration of vector into the nares of anesthetized supine animals. Transgene expression was consistently visible in the nasal cavity, trachea, and proximal to middle aspect of all lung lobes for all four methods, whereas transgene expression was consistently observed in the most distal aspect of lung lobes only with the intubation and intratracheal injection techniques. AAV vector genome copy numbers in the lung were approximately four-fold lower in mice that received vector via intranasal administration in comparison to the other three methods of vector delivery. The modified intranasal, intubation and intratracheal injection methods of vector administration did not yield statistical differences in AAV vector genome copy numbers in the lung. With regard to reproducibility of vector distribution within and between animals, the modified-intranasal technique was superior.ConclusionOur results show that mode of AAV vector administration to the murine respiratory tract should be selected based on desired target site and skill of the researcher, and that appropriate technique selection may greatly influence experimental outcomes.

Use of Precision-Cut Lung Slices as an Ex Vivo Tool for Evaluating Viruses and Viral Vectors for Gene and Oncolytic Therapy

Organotypic slice cultures recapitulate many features of an intact organ, including cellular architecture, microenvironment, and polarity, making them an ideal tool for the ex vivo study of viruses and viral vectors. Here, we describe a procedure for generating precision-cut ovine and murine tissue slices from agarose-perfused normal and murine melanoma tumor-bearing lungs. Furthermore, we demonstrate that these precision-cut lung slices can be maintained up to 1 month and can be used for a range of applications, which include characterizing the tissue tropism of viruses that cannot be propagated in cell monolayers, evaluating the transducing properties of gene therapy vectors, and, finally, investigating the tumor specificity of oncolytic viruses. Our results suggest that ex vivo lung slices are an ideal platform for studying the tissue specificity and cancer cell selectivity of gene therapy vectors and oncolytic viruses prior to in vivo studies, providing justification for pre-clinical work.

108. Pseudotyping Baculovirus Based Vectors for Enhanced In Vitro and In Vivo Delivery

Autographa californica multinucleopolyhedrovirus (AcMNPV) is the best-characterized baculovirus and the platform for well established recombinant protein and vaccine production technologies. In addition to countless examples of recombinant protein production, two commercially available vaccines (Cervarix, and Provenge) are produced via AcMNPV based expression technologies. More recently, Baculovirus based vectors have also garnered attention as gene delivery vectors, including for use in human gene therapy, because of several key characteristics. Baculoviruses can transduce cells of human origin, albeit at MOIs of 100-200, can accommodate large gene insertions (>38 kb), allowing for the inclusion of multiple genes, large promoters, and regulatory elements, are non-replicative in mammalian cells, do not integrate into mammalian chromosomes, and humans lack pre-existing immunity to baculoviruses. In vivo, Baculoviruses have been used to successfully transduce a wide variety of organs from mammalian species, such as mice, rats and rabbit. Despite these reports there is little information on the overall tissue distribution of in vivo delivered baculovirus. Here we test the transduction efficiency of wildtype and pseudotyped baculovirus vectors in various cell lines, and define the biodistribution of these vectors in C57BL/6 mice via intravenous, intrahepatic, and intranasal installation. In vitro, wildtype virus demonstrated good transduction of HEK293 cells and moderate to low transduction of cells originating from the lung and liver. Amongst the pseudotypes tested, the greatest transduction achieved across all cell types (in vitro) was a recombinant displaying a cell-penetrating-peptide-GP64 fusion protein (CPP-GP64), which demonstrated high levels of transduction across all cell lines tested. In vivo, overall transduction by wildtype virus was restricted to the kidneys and liver, and only at moderate to low levels. Similar to the in vitro results, inclusion of a CPP-GP64 greatly enhanced the transduction levels as well as expanded the tissue distribution of in vivo delivered vector.

181. Optimization of In Vivo Delivery of Baculovirus Gene Therapy Vectors for the Treatment of Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) is a single-gene disorder commonly associated with adult onset lung diseases, including emphysema, chronic obstructive pulmonary disease and airway inflammation. Alpha-1 antitrypsin (AAT) is produced primarily in hepatocytes and is subsequently secreted into the bloodstream and travels to the lung where it inhibits neutrophil elastase. Unregulated neutrophil elastase activity in individuals with AATD causes degradation of various components of the extracellular matrix producing damage to alveolar and airway epithelial cells. Furthermore, mutated AAT folds incorrectly causing intracellular aggregation within hepatocytes, which can result in liver damage in addition to pulmonary symptoms. The development of gene therapy strategies has been a popular approach for the treatment of AATD due to monogenic nature of this genetic disease. Recently, baculovirus based vectors have garnered attention for possible application in gene therapy due to multiple factors. Baculoviruses can tolerate large gene insertions (>38kb), are capable of transducing mammalian cells but not replicating or integrating into host chromosomes and finally, humans lack pre-existing immunity to these insect viruses. Although there are many characteristics that make baculovirus vectors attractive for use in gene therapy, there is little in vivo data on bio-distribution and tissue tropism in mammalian models. As AATD is a disease affecting both the liver and the lung, we examined several delivery routes of a baculovirus vector expressing the human placental alkaline phosphatase reporter gene in C57BL/6 mice. To target the lung we investigated intranasal and intratracheal administration and for liver delivery intravenous, intrahepatic and intraportal vein injections were utilized. Lung delivery of wild type baculovirus yielded little transduction, however intrahepatic injection resulted in moderate liver transduction as well as unexpected spread to other tissues. Different formulations of the baculovirus vector were examined for pulmonary delivery including a variety of viscoeleastic gels. Additionally, pharmacological agents such as clodronate liposomes to deplete macrophages and cobra venom factor to ablate complement activity were examined in an effort to bolster transduction.