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Adenovirus-mediated gene transfer into isolated mouse adult pancreatic islets: normal beta-cell function despite induction of an anti-adenovirus immune response.

The in vitro purification of pancreatic islets offers an opportunity for their modification by ex vivo gene transfer. We investigated the efficiency and functional consequences of adenovirus-mediated gene transfer into adult murine pancreatic islets with a recombinant adenovirus encoding for the beta-galactosidase (beta-Gal) reporter gene. At 10(6) pfu/islet, almost all of the islets were transduced, but maximal transduction was obtained at 10(7) pfu/islet. Histochemical analysis of frozen islet sections showed that transduced cells were only located at the periphery of islets. Transduced islets showed normal insulin secretion in vitro, and were able to normalize in vivo the glycemia of streptozotocin-induced diabetes in syngeneic and allogeneic mice. beta-Gal expression in transduced islets was observed for at least 6 weeks in naive normal recipients and in immunodeficient mice, but was shortened in mice preimmunized to adenovirus. Nevertheless, islets maintained normal control of glycemia in all mice. An early leukocyte infiltrate was observed in syngeneic grafts of transduced islets, but no acceleration in rejection of fully MHC-incompatible islet grafts occurred. In summary, adenovirus-mediated gene transfer in adult mouse islets, although sparing most of the beta-cells, was highly efficient and did not impair insulin secretion by islets. The immune response to the adenovirus and/or to the transgene might be only partially responsible for the decreased expression over time of the transduced gene. Accordingly, adenovirus-mediated gene transfer might allow efficient expression of vectorized sequences with potential immunosuppressive effects in the islet microenvironment.

Adenoviridae↗

Mouse adenovirus type 1 infection in SCID mice: an experimental model for antiviral therapy of systemic adenovirus infections.

The importance of human adenovirus infections in immunocompromised patients urges for new and adequate antiadenovirus compounds. Since human adenoviruses are species specific, animal models for systemic adenovirus infections rely on a nonhuman adenovirus. We established mouse adenovirus type 1 (MAV-1) infection of BALB/c SCID mice as a model for the evaluation of antiadenovirus therapy. In vitro studies with mouse embryonic fibroblasts pointed to the acyclic nucleoside phosphonate cidofovir and the N-7-substituted acyclic derivative 2-amino-7-(1,3-dihydroxy-2-propoxymethyl)purine (S-2242) as markedly active compounds against MAV-1. SCID mice, infected intranasally with MAV-1, developed a fatal disseminated infection after approximately 19 days, characterized by hemorrhagic enteritis. Several techniques were optimized to monitor viral, immunological, and pathological aspects of MAV-1 infection. Real-time PCR quantification of viral DNA revealed that after replication in the lungs, virus disseminated to several organs, including the brain, liver, spleen, intestine, heart, and kidneys (resulting in viruria). Immunohistochemical staining showed that MAV-1 was localized in the endothelial cells of the affected organs. Using reverse transcription-PCR, tissue levels of proinflammatory cytokines (i.e., interleukin-1beta and tumor necrosis factor alpha) were found to be markedly increased. The MAV-1/SCID model appears to be an appropriate model for in vivo evaluation of antiadenovirus agents. Treatment with cidofovir or S-2242 at a dose of 100 mg per kg of body weight resulted in a significant delay in MAV-1-related death, although these antivirals were unable to completely suppress virus replication despite continued drug treatment. These findings suggest that complete virus clearance during antiviral therapy for disseminated adenovirus infection may require an efficient adaptive immune response from the host.

3T3 Cells↗

Canine adenovirus vectors: an alternative for adenovirus-mediated gene transfer.

Preclinical studies have shown that gene transfer following readministration of viral vectors is often inefficient due to the presence of neutralizing antibodies. Vectors derived from ubiquitous human adenoviruses may have limited clinical use because preexisting humoral and cellular immunity is found in 90% of the population. Furthermore, risks associated with the use of human adenovirus vectors, such as the need to immunosuppress or tolerize patients to a potentially debilitating virus, are avoidable if efficient nonhuman adenovirus vectors are feasible. Plasmids containing recombinant canine adenovirus (CAV) vectors from which the E1 region had been deleted were generated and transfected into a CAV E1-transcomplementing cell line. Vector stocks, with titers greater than or equal to those obtained with human adenovirus vectors, were free of detectable levels of replication-competent CAV and had a low particle-to-transduction unit ratio. CAV vectors were replication defective in all cell lines tested, transduced human-derived cells at an efficiency similar to that of a comparable human adenovirus type 5 vector, and are amenable to in vivo use. Importantly, 49 of 50 serum samples from healthy individuals did not contain detectable levels of neutralizing CAV antibodies.

Adenoviridae↗

Hemorrhagic viral keratoconjunctivitis in Taiwan caused by adenovirus types 19 and 37: applicability of polymerase chain reaction-restriction fragment length polymorphism in detecting adenovirus genotypes.

PURPOSE: Acute keratoconjunctivitis with prominent subconjunctival hemorrhage (SCH) is usually perceived by a clinician as acute hemorrhagic conjunctivitis (AHC) associated with enteroviruses; however, SCH can also be an adenoviruses infection. A rapid and sensitive laboratory diagnosis is helpful for differential diagnosis. Therefore, the sensitivity and applicability of polymerase chain reaction (PCR) and reverse transcription (RT)-PCR diagnoses were evaluated for keratoconjunctivitis associated with viral infection. METHODS: Conjunctival swabs from patients with acute conjunctivitis were tested using a PCR-restriction fragment length polymorphism (PCR-RFLP) for adenovirus detection and RT-PCR for enterovirus detection. The results were compared with those using the culture isolation and neutralization test; also, the clinical findings of the patients were analyzed with special attention to SCH patterns. RESULTS: Neither coxsackievirus A type 24 variant (CA24v) nor enterovirus type 70 (EV70) was detected in 113 patients with acute conjunctivitis. The positive results of adenovirus (Ad) were 39.9% by the PCR method and 37.1% by culture isolation. For the patients with adenoviral conjunctivitis, 68.1% was owing to Ad37 and 19.2% was owing to Ad19. SCH was present in 51.5% of the positive cases, and 44.7% of the Ad-positive patients had secondary illnesses. CONCLUSIONS: SCH can be a predominant presentation of Ad19 and Ad37 keratoconjunctivitis and may herald a new stage in the evolution of adenoviruses. PCR and PCR-RFLP are rapid and reliable methods for Ad detection and typing; however, if the amplified genes and restriction enzymes are not properly selected, they may not be able to detect new genotypes of adenoviruses or the evolution of these viruses.

Adenovirus Infections, Human↗

Complementation of a human adenovirus early region 4 deletion mutant in 293 cells using adenovirus-polylysine-DNA complexes.

The E1 deleted adenoviral vectors are efficient at gene transfer to cells in culture or in animals. However, their use is limited because of an immune-mediated loss of transduced cells. This immune response is believed to result from low-level production of viral antigens from these vectors after gene transfer. The early region 4 (E4) of adenovirus produces a number of proteins that play an important role in adenoviral and host gene regulation during infection of mammalian cells. There is interest in developing E4 deficient adenovirus for gene therapy, especially in the context of developing a combined E1/E4 deleted vector. Towards this goal, a method by which to complement and propagate an E4 deficient adenovirus (dl 1014) in the E1 complementing 293 cell line, using a novel and simple rescue technique, has been developed. Purified adenovirus deficient in E4 gene expression (dl 1014) was conjugated to expression plasmids containing the E4-open reading frame 6 gene or complete E4 region to produce adenovirus-polylysine-DNA complexes that were used to transfect 293 cells. The derived virus obtained from this transfection did not replicate on 293 cells but did replicate on W162 cells (E4+) confirming that the virus was indeed deleted for E4. Viral yield was high ranging from 3 x 10(8) to 9 x 10(8) plaque forming units per 10(6) 293 cells. This method has general application to the production of new adenoviral mutants that will be useful for developing second generation adenoviral vectors.

Adenovirus E4 Proteins↗

Adenovirus 37: identification and characterization of a medically important new adenovirus type of subgroup D.

A new human adenovirus has been isolated from 62 eyes with (kerato)conjunctivitis and from nine genitourinary sites. The virus is closely related in haemagglutination inhibition tests to adenovirus type 19 (Ad 19) and Ad 10. Antiserum adsorption experiments demonstrated the presence of three haemagglutinin antigens in the virus: One unique, another common to Ad 19, and a third common to Ad 10 and 19. In neutralization tests, the virus is distantly related to Ad 13, 30, 19, and 10. Despite this relationship, it is proposed to call the virus adenovirus 37, in agreement with current species definitions. It belongs to subgroup D of human adenoviruses. Antisera to the new virus show virtually no neutralization of other human adenovirus types. Only bay use of this antiserum it is in practice possible to avoid wrong or indefinite typing, which has often occurred in the past.

Adenoviruses, Human↗

Supernatant rescue assay vs. polymerase chain reaction for detection of wild type adenovirus-contaminating recombinant adenovirus stocks.

The certification of recombinant adenoviruses prepared for clinical use requires the exclusion of contaminating, replication-competent adenovirus (wild type virus). Polymerase chain reaction (PCR)-based detection assays have been developed that detect the presence of viral sequences present only in wild type adenoviruses. As an alternative, this report describes a novel bioassay, designated the 'supernatant rescue assay', that detected minimal amounts of wild type virus mixed with high numbers of recombinant adenoviruses. This assay is based on the observation that minimal numbers of wild type adenovirus can be rescued from the supernatants of cells exposed to high multiplicities of infection (mois) of recombinant virus mixed with a known, minimal number of wild type virions. This assay was highly reproducible and routinely detected the presence of a single wild type virus mixed within 10(9) recombinant viruses. Under the experimental conditions employed, the supernatant rescue assay was significantly more sensitive than all three different PCR-detection assays.

Adenoviruses, Human↗

Deletion of the intracellular domain of coxsackie and adenovirus receptor (CAR) enhances the expression of itself and boosts the efficiency of current adenovirus-mediated gene therapy in ovarian cancer cell lines in vitro.

The failure of adenovirus-mediated gene therapy often derives from the absence of coxsackie and adenovirus receptor (CAR) expression in target cells. We hypothesize that the slight up-regulation of CAR expression might boost the effect of adenovirus-mediated gene therapy in ovarian cancer. To test this hypothesis, we transfected full-length and intracellular-domain-deleted (tailless) CAR plasmids into CAR-deficient ovarian cancer cell line SKOV3. We observed significant elevations of the in vitro killing effect of Adv-TK and oncolytic adenovirus-mediated cytopathic effect (CPE) in transfected sub-clones, and tailless-transfected SKOV3 showed higher CAR expressions than full-length CAR-transfected cells. We conclude that the extracellular domain of CAR is essential for adenovirus-based gene therapy and, furthermore, that its intracellular domain might play an important role in the regulation of its own expression.

Adenoviridae Infections↗

Mouse adenovirus type 1 attachment is not mediated by the coxsackie-adenovirus receptor.

Common human adenovirus (Ad) vectors are derived from serotype 2 or 5, which use the coxsackie-adenovirus receptor (CAR) as their primary cell receptor. We investigated the receptor usage of mouse adenovirus type 1 (MAV-1), which in vivo is characterized by a pronounced endothelial cell tropism. Alignment of the fiber knob sequences of MAV-1 and those of CAR-using adenoviruses, revealed that amino acid residues, critical for interaction with CAR, are not conserved in the MAV-1 fiber knob. Attachment of MAV-1 to Chinese hamster ovary (CHO) cells was not increased by stable transfection with mouse CAR, whereas the binding efficiency of Ad2 was 20-fold higher in the mouse CAR-transfectant compared to the wild type cells. Also, purified fiber knob of Ad5, which is interchangeable with the Ad2 fiber knob, did not compete with MAV-1 for receptor binding, indicating that MAV-1 binds to a receptor different from CAR. These results support further exploration of an MAV-1-derived vector as a potential vehicle for gene delivery to cell types which are not efficiently transduced by human adenovirus vectors.

Adenoviridae↗

Coxsackievirus-adenovirus receptor expression in ovarian cancer cell lines is associated with increased adenovirus transduction efficiency and transgene expression.

The expression of coxsackievirus-adenovirus receptor (CAR) and the integrins alpha(v)beta3 and alpha(v)beta5 was analyzed quantitatively (flow cytometry) and qualitatively (immunocytochemistry) in five human ovarian cancer cell lines (PEO1, PEO4, PEO14, SKOV-3, and OVCAR-3) and three control cell lines (293, HeLa, and CHO-K1). The transduction efficiencies were evaluated by adv/rsv-beta-Gal transduction followed by X-gal staining. The effects of 17beta-estradiol on cell growth, CAR and integrins alpha(v)beta3/5 expression, adenovirus transduction efficiency, and cell-killing efficacy of adv/rsv-tk plus ganciclovir were determined. The levels of CAR, integrin alpha(v)beta3, and integrin alpha(v)beta5 showed great variation between the cell lines. Whereas the expression of CAR appeared to be essential for and positively correlated with adenovirus transduction efficiency, the integrins alpha(v)beta3 and alpha(v)beta5 were not absolutely necessary for adenovirus transduction even though their presence may facilitate transduction. In PEO4 and PEO1 cells, proliferation was stimulated by 17beta-estradiol in a dose-dependent manner. In PEO4 cells, and much less pronounced in PEO1 cells, this was accompanied by an increase in CAR expression. The stimulation of CAR expression was paralleled by an increased transduction efficiency resulting in an increased cell-killing efficacy. Our data suggest that the expression of CAR is one of the most important prerequisites for successful adenovirus-mediated gene therapy of ovarian cancer.

Adenoviridae↗

Coxsackievirus and adenovirus receptor (CAR)-positive immature osteoblasts as targets of adenovirus-mediated gene transfer for fracture healing.

Adenovirus vectors are expected to be a powerful tool for gene therapy to treat severe fractures. Adenovirus invades cells through binding to the coxsackievirus and adenovirus receptor (CAR) on the cell membrane. CAR expression is low in normal adult animals, but it is induced on regenerating cells in some experimental models. We made a rib fracture model in mice and evaluated the histological changes and CAR mRNA expression by RT-PCR 1, 5, 10, 14, and 21 days after the fracture. CAR mRNA was expressed exclusively in the fractured ribs at each time point, but not in the normal ribs. We detected the CAR protein immunohistochemically in fibroblast-like cells in the fracture callus on days 10 and 14 after fracture. In situ hybridization showed that these fibroblast-like cells expressed mRNA of type I collagen and osteopontin, but not osteocalcin, defining the cells as immature osteoblasts. We then transferred small doses (10(4)-10(8) PFU) of lacZ-expressing adenovirus vector into immature osteoblasts on day 14. beta-galactosidase was detected only on the immature osteoblasts at every dose. Immature osteoblasts play an important role in the matrix replacement step in fracture healing. CAR-mediated gene transfer into immature osteoblasts can be reasonable for adenovirus-mediated treatment of fracture healing.

Adenoviridae↗

Coxsackie adenovirus receptor and alpha nu beta3/alpha nu beta5 integrins in adenovirus gene transfer of rat cochlea.

This study was designed to determine whether Coxsackie adenovirus receptor (CAR) and alpha nu beta3/alpha nu beta5 integrin co-receptors are involved in adenovirus gene transfer in the rat cochlea. We find that CAR and integrin co-receptors are expressed in every cell subtype transduced by the adenoviral vector Ad5 DeltaE1-E3/cytomegalovirus/green fluorescent protein (GFP) on cochlear slices in vitro. The spiral ganglion neurons, which do not express CAR, were not transduced by the virus. Blocking these receptors by monoclonal antibodies decreased transgene expression, whereas disrupting tight junctions with ethylenediaminetetraacetic acid led to an increased transgene expression. However, sensory hair cells and strial cells also expressing CAR and alpha nu integrins were not transduced by the vector. GFP expression was also studied in vivo. Perilymphatic perfusion of adenovirus in vivo did not affect hearing and only cells lining the perilymphatic spaces were transduced. Endolymphatic perfusion resulted in low-frequency hearing loss and although some cells of the organ of Corti were efficiently transduced, the sensory and the strial cells were not. Transduced sensory and strial cells were occasionally observed in cochleas after single shot of adenovirus. Pretreatment with anti-CAR and anti-alpha nu antibodies decreases GFP expression in vivo, suggesting that the CAR/alpha nu integrin pathway is involved in adenovirus transduction in the cochlea.

Action Potentials↗

Structural and mutational analysis of human Ad37 and canine adenovirus 2 fiber heads in complex with the D1 domain of coxsackie and adenovirus receptor.

Adenovirus fibers from most serotypes bind the D1 domain of coxsackie and adenovirus receptor (CAR), although the binding residues are not strictly conserved. To understand this further, we determined the crystal structures of canine adenovirus serotype 2 (CAV-2) and the human adenovirus serotype 37 (HAd37) in complex with human CAR D1 at 2.3 and 1.5A resolution, respectively. Structure comparison with the HAd12 fiber head-CAR D1 complex showed that the overall topology of the interaction is conserved but that the interfaces differ in number and identity of interacting residues, shape complementarity, and degree of conformational adaptation. Using surface plasmon resonance, we characterized the binding affinity to CAR D1 of wild type and mutant CAV-2 and HAd37 fiber heads. We found that CAV-2 has the highest affinity but fewest direct interactions, with the reverse being true for HAd37. Moreover, we found that conserved interactions can have a minor contribution, whereas serotype-specific interactions can be essential. These results are discussed in the light of virus evolution and design of adenovirus vectors for gene transfer.

Adenoviridae↗

Coxsackie and adenovirus receptor binding ablation reduces adenovirus liver tropism and toxicity.

Human adenovirus-based vectors have emerged as a new promising vehicle for in vivo gene transfer-mediated therapy. However, the full potential of this methodology has not been fully realized because of the nonspecific tissue distribution of adenoviral vectors. Adenovirus infection is initiated by forming a complex between the fiber protein and a ubiquitously expressed host cell membrane protein, coxsackie B virus and adenovirus receptor (CAR). Therefore, ablating the adenovirus vector's ability to bind to the CAR is the first step in redirecting adenoviral tropism. To ablate CAR binding, we mutated the Bbeta sheet of the fiber knob, generating CAR-binding ablated replication-incompetent (dl-K420A-Z) and replication-competent (YKLK420A) adenoviral vectors. The in vitro transduction efficiency of dl-K420A-Z was significantly reduced in comparison to dl-LacZ carrying the wild-type fiber in CAR-positive cells but not in CAR-negative cells, suggesting that the mutation introduced in the Bbeta sheet of the fiber knob could disable the CAR-dependent transduction pathway. The in vivo transduction was also dramatically reduced in the liver and other organs for mice treated with dl-K420A-Z, compared with a cognate control vector, dl-LacZ. Concomitant with this attenuated gene transfer efficiency in vivo was a substantial reduction in the amount of general toxicity observed in the YKL-K420A-treated mice. Diminished toxicity was surmised from quantitative measurement of serum level of enzymes for liver and kidney function, hematologic chemistries, histopathology, and differences in lethality. Significant decrease in serum transaminases (alanine transferase [ALT] and aspartate transferase [AST]) was observed in mice treated with YKL-K420A. In addition, the lethality was lower in the YKLK420A- treated groups compared to the YKL-1-treated groups at all doses examined. Furthermore, the hepatopathologic analysis revealed that YKL-1 induced focal zonal necrosis and hepatocyte degeneration, while YKL-K420A induced mild spotty necrosis. In summary, this decreased vector tropism of CAR-binding ablated adenoviruses in normal tissues may increase the amount of virus available for infecting tumor cells and thus increase the antitumor efficacy with fewer unwanted side effects.

Adenoviridae↗

Complete genome sequence of simian adenovirus 1: an Old World monkey adenovirus with two fiber genes.

Simian adenovirus 1 (SAdV-1) is one of many adenovirus strains that were isolated from Old World monkey cells during poliomyelitis vaccine production several decades ago. Despite the availability of these viruses, knowledge of their genetic content and phylogeny is rudimentary. In the present study, the genome sequence of SAdV-1 (34,450 bp) was determined and analysed. In regions where genetic content varies between primate adenoviruses, SAdV-1 has a single virus-associated RNA gene, six genes in each of the E3 and E4 regions and two fiber genes. SAdV-1 clusters phylogenetically with HAdV-40, a member of human adenovirus species HAdV-F, which also has two fiber genes. However, based on phylogenetic distances and other taxonomic criteria, SAdV-1 is proposed to represent a novel adenovirus species.

Adenoviruses, Simian↗

Conserved sequences of the adenovirus genome for detection of all human adenovirus types by hybridization.

The application of DNA hybridization directly to clinical specimens has the potential of improving the diagnosis of fastidious types of adenovirus. In this study, the genome of one adenovirus type from each human subgenus (A to F) was systematically evaluated by hybridization for homologous sequences to find the optimal common probe for detection of all human adenovirus types. The area of cross-hybridization, most closely defined with adenovirus type 2 (Ad2), mapped from map units 11.4 to 16.1 and 26.9 to 29.7 and, principally, to a central area of the genome between map units 47.5 and 65.2. The last area, enclosing the hexon gene, was highly conserved. Cloned probes generated from this area demonstrated the greatest homology to heterologous types by hybridization analysis. A HindIII-BglII clone containing the hexon gene of Ad2 within narrow confines reacted most evenly with all adenoviral types and detected the DNA of all other subgenera with a sensitivity 2 logs greater than that of a complete genomic Ad2 probe. The most homologous adenoviral gene sequences were observed in genes involved with DNA replication or intimately connected to the hexon in the early capsid formation. These results show that the hexon gene constitutes the best single region of the adenovirus genome for use as a genus-specific probe for the diagnosis of all human adenoviral subgenera by DNA hybridization.

Adenoviruses, Human↗

Regulation of integrated adenovirus sequences during adenovirus infection of transformed cells.

A human cell line (293) transformed by adenovirus type 5 encodes mRNA's and proteins from the early region 1 (E1) of the viral genome. These products correspond to those synthesized early after adenovirus infection of normal cells. This pattern of expression is different from that observed at later times in the lytic cycle. We have determined whether integrated sequences can undergo the early-late transition during infection of transformed cells. Cultures of 293 cells were infected with mutants of adenovirus type 5 that have deletions in EI genes. In such infections, the integrated sequence complements the deletion mutants so that viral DNA replication, late mRNA and protein synthesis, and viral assembly occur. Because the infecting genomes lack EI sequences, the products synthesized from the integrated DNA could be analyzed. In contrast to the early-late transition that occurs with EI DNA in free viral genomes, the pattern of mRNAs and proteins made from the integrated sequences was restricted to the early pattern. Assuming that the viral sequences in 293 cells have not become altered during the history of the cells, our results suggest that regulation of integrated adenovirus genes may not be determined exclusively by nucleotide sequence recognition. Apparently, during infection certain factors prevent the integrated viral genes from responding to the regulatory signals which control late expression from free EI DNA. The distinction between integrated and free viral sequences might reflect the different fates of viral and host transcripts during the lytic cycle of adenovirus.

Adenoviruses, Human↗

Polar encapsidation of adenovirus DNA: cloning and DNA sequence of the left end of adenovirus type 3.

The left-end adenovirus type 3 DNA sequence is very similar to those of other subgroup B adenoviruses, especially in the area between the HinfI site (320 base pairs) and the early-region Ia gene. This segment of the genome has been implicated as necessary for the left-end polarity of adenovirus DNA encapsidation. This segment and the sequences flanking it are compared with the corresponding sequences of adenovirus type 5 and adenovirus type 12, and the extent and pattern of intersubgroup homologies are discussed.

Adenoviruses, Human↗