Human adenovirus serotypes 4p and 11p are efficiently expressed in cell lines of neural tumour origin

Adenovirus Isolated From a Cat Is Related to Human Adenovirus 1

An adenovirus (AdV) has been isolated from the rectal swab of a domestic cat (Felis catus) and named feline adenovirus (FeAdV) isolate. It replicates and causes cytopathological effects in many human, feline, other mammalian cell lines that have both Coxsackie-adenovirus-receptor and integrins. Its antigens cross-react with anti-human adenovirus antibodies in immunofluorescence and immunocytochemistry assays. Electron microscopy revealed typical extracellular icosahedral particles and pseudo arrays inside cells. Sequence analysis of hexon and fiber genes indicates that this virus might belong to human adenovirus (HAdV) C species and might be a variant of type 1. In the fiber protein, three altered amino acids occur in the shaft; four altered residues are found in the knob region as compared to a European HAdV might be type 1 isolate (strain 1038, D11). One alteration affects amino acid 442 forming an RGS motif in an alanine rich region that might be an alternative way to bind integrins with subsequent internalization. Substitutions in the hexon sequence are silent. As compared to published HAdV sequences, the fiber is related to the original American prototype and recently described Taiwanese HAdV 1 isolates, but the hexon sequences are related to adenovirus isolates from France, Germany, Japan, and Taiwan. Serology carried out on FeAdV infected M426 cells indicates a prevalence of IgG in 80% of domestic cats in Delaware, United States. FeAdV isolate seems to be a recently recognized virus with possible pathogenic effects and, simultaneous human and feline infections are possible. Further molecular and biological characterization of this feline adenovirus isolate, as well as studies on both human and feline epidemiology and pathomechanisms, especially in endangered big cats, are warranted. FeAdV might have further practical advantages. Namely, it could be utilized in both human and feline AIDS research, developed into diagnostic tools, and gene therapy vectors in the near future.

Fiber-modified adenovirus for central nervous system Parkinson's disease gene therapy

Gene-based therapies for neurological diseases continue to develop briskly. As disease mechanisms are elucidated, flexible gene delivery platforms incorporating transcriptional regulatory elements, therapeutic genes and targeted delivery are required for the safety and efficacy of these approaches. Adenovirus serotype 5 (Ad5)-based vectors can carry large genetic payloads to provide this flexibility, but do not transduce neuronal cells efficiently. To address this, we have developed a tropism-modified Ad5 vector with neuron-selective targeting properties for evaluation in models of Parkinson disease therapy. A panel of tropism-modified Ad5 vectors was screened for enhanced gene delivery in a neuroblastoma cell line model system. We used these observations to design and construct an unbiased Ad vector platform, consisting of an unmodified Ad5 and a tropism-modified Ad5 vector containing the fiber knob domain from canine Ad serotype 2 (Ad5-CGW-CK2). Delivery to the substantia nigra or striatum showed that this vector produced a neuronally-restricted pattern of gene expression. Many of the transduced neurons were from regions with afferent projections to the injection site, implicating that the vector binds the presynaptic terminal resulting in presynaptic transduction. We show that Ad5-CGW-CK2 can selectively transduce neurons in the brain and hypothesize that this modular platform is potentially adaptable to clinical use.

Transduction and oncolytic profile of a potent replication-competent adenovirus 11p vector (RCAd11pGFP) in colon carcinoma cells

Replication-competent adenovirus type 5 (Ad5) vectors promise to be more efficient gene delivery vehicles than their replication-deficient counterparts, and chimeric Ad5 vectors that are capable of targeting CD46 are more effective than Ad5 vectors with native fibers. Although several strategies have been used to improve gene transduction and oncolysis, either by modifying their tropism or enhancing their replication capacity, some tumor cells are still relatively refractory to infection by chimeric Ad5. The oncolytic effects of the vectors are apparent in certain tumors but not in others. Here, we report the biological and oncolytic profiles of a replication-competent adenovirus 11p vector (RCAd11pGFP) in colon carcinoma cells. CD46 was abundantly expressed in all cells studied; however, the transduction efficiency of RCAd11pGFP varied. RCAd11pGFP efficiently transduced HT-29, HCT-8, and LS174T cells, but it transduced T84 cells, derived from a colon cancer metastasis in the lung, less efficiently. Interestingly, RCAd11p replicated more rapidly in the T84 cells than in HCT-8 and LS174T cells and as rapidly as in HT-29 cells. Cell toxicity and proliferation assays indicated that RCAd11pGFP had the highest cell-killing activities in HT29 and T84 cells, the latter of which also expressed the highest levels of glycoproteins of the carcinoma embryonic antigen (CEA) family. In vivo experiments showed significant growth inhibition of T84 and HT-29 tumors in xenograft mice treated with either RCAd11pGFP or Ad11pwt compared to untreated controls. Thus, RCAd11pGFP has a potent cytotoxic effect on colon carcinoma cells.

Adenoviruses 16 and CV23 efficiently transduce human low-passage brain tumor and cancer stem cells

Most clinical protocols involving adenovirus (Ad) vectors for gene therapy use a vector based on serotype 5 (Ad5). We believe that this serotype is not suitable for all gene therapy applications and that alternative vectors based on other serotypes should be developed. We have compared the ability of Ad5, Ad11p, Ad16p, and a chimpanzee Ad (CV23) to infect human low-passage brain tumor cells as well as primary glioma cells sorted into a CD133(+) and CD133(-) population. Cancer stem cells have been shown to reside in the CD133(+) population of cells in human glioma tumors and they are of considerable interest in glioma therapy. Ad16p and CV23 infected the low-passage brain tumor cell lines and also the CD133(+) and CD133(-) primary tumor cells most efficiently. Interestingly, as the passage number of the cells increased, the infection capacity of Ad5 increased significantly, whereas this was not seen for CV23. To ensure the therapeutic effect of Ad vectors on brain tumors, the vector must be capable of addressing both the CD133(+) cancer stem cells and the CD133(-) cells of the tumor. In particular, Ad16 and CV23 are meeting this challenge.

Conditionally replicative adenoviral vectors for malignant glioma

High-grade gliomas constitute an important challenge to modern medicine, and although great effort has been made to prolong patient survival, the prognosis for this disease remains poor. Due to recent discoveries in the molecular basis of gliomas, gene therapy is becoming a promising alternative. In this review, we discuss the use of conditionally replicative adenoviral vectors (CRAd) and their applications in neuro-oncology. Such vectors, when rendered conditionally replicative via transductional and transcriptional modifications, offer great promise for patients with malignant brain tumours. We review data from preclinical and clinical studies utilising such vectors and discuss the limitations and future perspectives of CRAd oncolytic therapy for malignant glioma.

Development and assessment of human adenovirus type 11 as a gene transfer vector

Adenovirus vectors based on human serotype 5 (Ad5) have successfully been used as gene transfer vectors in many gene therapy-based approaches to treat disease. Despite their widespread application, many potential therapeutic applications are limited by the widespread prevalence of vector-neutralizing antibodies within the human population and the inability of Ad5-based vectors to transduce important therapeutic target cell types. In an attempt to circumvent these problems, we have developed Ad vectors based on human Ad serotype 11 (Ad11), since the prevalence of neutralizing antibodies to Ad11 in humans is low. E1-deleted Ad11 vector genomes were generated by homologous recombination in 293 cells expressing the Ad11-E1B55K protein or by recombination in Escherichia coli. E1-deleted Ad11 genomes did not display transforming activity in rodent cells. Transduction of primary human CD34+ hematopoietic progenitor cells and immature dendritic cells was more efficient with Ad11 vectors than with Ad5 vectors. Thirty minutes after intravenous injection into mice that express one of the Ad11 receptors (CD46), we found, in a pattern and at a level comparable to what is found in humans, Ad11 vector genomes in all analyzed organs, with the highest amounts in liver, lung, kidney, and spleen. Neither Ad11 genomes nor Ad11 vector-mediated transgene expression were, however, detected at 72 h postinfusion. A large number of Ad11 particles were also found to be associated with circulating blood cells. We also discovered differences in in vitro transduction efficiencies and in vivo biodistributions between Ad11 vectors and chimeric Ad5 vectors possessing Ad11 fibers, indicating that Ad11 capsid proteins other than fibers influence viral infectivity and tropism. Overall, our study provides a basis for the application of Ad11 vectors for in vitro and in vivo gene transfer and for gaining an understanding of the factors that determine Ad tropism.

Robust infectivity and replication of Delta-24 adenovirus induce cell death in human medulloblastoma

The diverse advanced treatment modalities currently available to children with medulloblastoma, including surgery and radiotherapy, are associated with deleterious side effects and often with an unfavorable prognosis. A mutant adenovirus, Delta-24, which has a 24-base pair deletion in the Rb-binding region of the E1A gene, demonstrates selective replication and oncolysis in various malignant phenotypes. Here we report the ability of Delta-24 to kill medulloblastoma cells. Flow cytometric analyses of cell receptors demonstrated expression of the coxsackie adenovirus receptor and RGD-related integrins in the assessed medulloblastoma cell lines. Infectivity assays using a replication-deficient adenovirus to transduce the green fluorescence protein gene showed that the Delta-24 adenovirus infects 99% of Daoy and 46% of D283 Med medulloblastoma cells at a multiplicity of infection (MOI) of 50. Within 4 days after infecting medulloblastoma cells with Delta-24, a noticeable cytopathic effect was produced. Delta-24 induced a total cytopathic effect in Daoy and D283 Med medulloblastoma cells after 6 and 8 days of infection, respectively. In the infected population of cells, cell death correlated with the accumulation of cells in the S phase. At 5 days post-infection with 2.5 MOIs of Delta-24 adenovirus, the percentage of Daoy medulloblastoma cells in the S phase increased to 71.9+/-5.5%, compared with control values of 20.5+/-1.4%. The release of viral progeny was quantified as being increased by two orders of magnitude, indicating efficient replication of Delta-24 in medulloblastoma cells. This is the first report of the ability of oncolytic adenoviruses to infect and kill medulloblastoma cells, the findings of which suggest the potential efficacy of Delta-24 as a therapy for human medulloblastoma tumors.

Human hematopoietic (CD34+) stem cells possess high-affinity receptors for adenovirus type 11p

Gene transfer into human hematopoietic stem cells using Ad5 is inefficient due to lack of the primary receptor CAR and the secondary receptors alphavbeta3 integrin and alphavbeta5 integrin, and due to the high seroprevalence of Ad5 antibodies in most adults, resulting in diminished gene transduction. In the present study, we screened six species (species A-F) of adenovirus, displaying different tropisms for interaction with CD34+ cells, at the level of virus attachment and expression. Virus particles were biotinylated and their binding capacity was determined by FACS analysis using streptavidin-FITC. Ad11p, Ad35, and Ad3 (species B) showed high binding affinity, while Ad7, Ad11a (species B), and Ad37 (species D) displayed intermediate affinity. Virions of Ad4 (species E), Ad5 (species C), Ad31 (species A), and Ad41 (species F) hardly bound to hematopoietic progenitor cells. Using a double-labeling system, we demonstrated that adenoviruses bind to quiescent CD34+ cells. Ad11p virions showed the highest affinity among the adenoviruses detected. We further confirmed that virus fiber-specific receptors were present on the hematopoietic progenitor cell surface, because both recombinant fiber of Ad11p and specific antiserum against rfiber could block virus attachment. The ability of the adenoviruses to infect hematopoietic cells was studied by immunofluorescence staining. The adenoviruses from species B and Ad37 showed higher infectivity than Ad31, Ad5, Ad4, and Ad41. Among the studied species B adenoviruses, Ad11p manifested a superior infectivity. Thus, we have confirmed that these cells have high-affinity receptors for species B:2 human adenovirus, Ad11p, and this virus may be used as candidate vector to target therapeutic genes to hematopoietic stem cells.

Efficient internalization into low-passage glioma cell lines using adenoviruses other than type 5: an approach for improvement of gene delivery to brain tumours

There is a need for improvement of the commonly used adenovirus vectors based on serotype 5. This study was performed on three adenovirus serotypes with a CAR-binding motif (Ad4p, Ad5p and Ad17p) and three non-CAR-binding serotypes (Ad11p, Ad16p and Ad21p). The capacity of these alternative adenovirus vector candidates to deliver DNA into low-passage glioma cell lines from seven different donors was evaluated. The non-CAR-binding serotype Ad16p was the most efficient serotype with regard to import of its DNA, as well as initiation of hexon protein expression. Ad16p established hexon expression in 60–80 % of the cell population in gliomas from all donors tested. The other non-CAR-binding serotypes, Ad11p and Ad21p, showed hexon expression in 25–60 and 40–80 % of cells, respectively. The corresponding figure for the best CAR-binding serotype, Ad5p, was only 25–65 %, indicating greater variability between cells from different donors than serotype Ad16p had. The other CAR-binding serotypes, Ad4p and Ad17p, were refractory to some of the gliomas, giving a maximum of only 45 and 40 % hexon expression, respectively, in the most permissive cells. Interestingly, the transduction capacity of the CAR-binding serotypes was not correlated to the level of CAR expression on the cells.

Adenovirus type 11 uses CD46 as a cellular receptor

The 51 human adenovirus serotypes are divided into six species (A to F). Many adenoviruses use the coxsackie-adenovirus receptor (CAR) for attachment to host cells in vitro. Species B adenoviruses do not compete with CAR-binding serotypes for binding to host cells, and it has been suggested that species B adenoviruses use a receptor other than CAR. Species B adenoviruses mainly cause disease in the respiratory tract, the eyes, and in the urinary tract. Here we demonstrate that adenovirus type 11 (Ad11; of species B) binds to Chinese hamster ovary (CHO) cells transfected with CD46 (membrane cofactor protein)-cDNA at least 10 times more strongly than to CHO cells transfected with cDNAs encoding CAR or CD55 (decay accelerating factor). Nonpermissive CHO cells were rendered permissive to Ad11 infection upon transfection with CD46-cDNA. Soluble Ad11 fiber knob but not Ad7 or Ad5 knob inhibited binding of Ad11 virions to CD46-transfected cells, and anti-CD46 antibodies inhibited both binding of and infection by Ad11. From these results we conclude that CD46 is a cellular receptor for Ad11.

Comparative analysis of the genome organization of human adenovirus 11, a member of the human adenovirus species B, and the commonly used human adenovirus 5 vector, a member of species C

Adenovirus type 11 (Ad11), a member of the human adenovirus species B (HAdV-B), has a tropism for the urinary tract. The genome of Ad11 was found to comprise 34 794 bp and is 1141 bp shorter than the Ad5 genome of species HAdV-C. The G+C content of the Ad11 genome is 48.9 %, whereas that of Ad5 is 55.2 %. Ad11 and Ad5 share 57 % nucleotide identity and possess the same four early regions, but the E3 region of Ad11 could not be divided into E3A and E3B. The late genes of Ad11 and Ad5 are organized into six and five regions, respectively. Thirty-eight putative ORFs were identified in the Ad11 genome. The ORFs in the late regions, the E2B region and IVa2 show high amino acid identity between Ad11 and Ad5, whereas the ORFs in E1, E2A, E3 and E4, protein IX and the fibre protein show low amino acid identity. The highest and lowest identities were noted in the pre-terminal protein and fibre proteins: 85 % and 24.6 %, respectively. The E3 20.3K and 20.6K ORFs and the L6 agnoprotein were present in the Ad11 genome only, whereas the E3 11.6K cell death protein was identified only in Ad5. All ORFs but the E3 10.3K and L4 pVIII protein vary not only in composition but also in size. Ad11 may have a higher vector capacity than Ad5, since it has a shorter genome and a shorter fibre. Furthermore, in the E3 region, two additional ORFs can be deleted to give extra capacity for foreign DNA.

Human adenovirus serotypes 4 and 11 show higher binding affinity and infectivity for endothelial and carcinoma cell lines than serotype 5

Adenoviruses are promising vectors for human cancer gene therapy. However, the extensively used adenoviruses serotypes 2 and 5 (Ad2 and Ad5) from species C have a major disadvantage in being highly prevalent; thus, most adults have an immunity against the two viruses. Furthermore, the expression of coxsackievirus and adenovirus receptors for Ad2 and Ad5 varies in different cells. This study aims to identify adenovirus serotypes with specific tropism for endothelial cells and epithelial tumour cells. Comparison of the binding affinities of Ad31, Ad11, Ad5, Ad37, Ad4 and Ad41, belonging to species A-F, respectively, to established cell lines of hepatoma (HepG2), breast cancer (CAMA and MG7), prostatic cancer (DU145 and LNCaP) and laryngeal cancer (Hep2), as well as to endothelial cells (HMEC), was carried out by flow cytometric analysis. Ad11 from species B showed markedly higher binding affinity than Ad5 for the endothelial cell line and all carcinoma cell lines studied. Ad4 showed a specific binding affinity for hepatoma cells and laryneal carcinoma cells. The ability of Ad11, Ad4 and Ad5 to be expressed in hepatoma, breast cancer and endothelial cell lines was studied by immunostaining and (35)S-labelling of viral proteins in infected cells. Ad11 and Ad4 manifested a higher proportion of infected cells and a higher degree of hexon expression than Ad5.