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Comparative analysis of adenovirus fiber-cell interaction: adenovirus type 2 (Ad2) and Ad9 utilize the same cellular fiber receptor but use different binding strategies for attachment.

We have analyzed the binding of adenovirus (Ad) serotypes from subgroups B, C, and D through fiber-virus and fiber-fiber cross-competition experiments. Since viruses in these distinct subgroups display markedly different tropisms, it was unexpected that the subgroup C viruses Ad2 and 5 and the subgroup D virus Ad9 cross-competed for the same cellular fiber receptor. The subgroup B serotype Ad3 recognized a receptor distinct from the Ad2, 5, and 9 fiber receptor. However, despite sharing the same fiber receptor, Ad2 and Ad9 displayed markedly different binding characteristics that appeared to result from direct Ad9 binding to cells via alpha(v)-integrins. Unlike Ad2, Ad9 binding to many cell lines was not abrogated by competition with the fiber 9 knob (F9K). Ad9 binding to fiber receptor-deficient cells was blocked by a monoclonal antibody to alpha(v)-integrins. In contrast, Ad9 binding to alpha(v)-deficient cells that express fiber receptor was blocked by F9K. Transfection of an alpha(v)-integrin-deficient cell line with a plasmid that expresses alpha(v)beta5 resulted in Ad9 binding that was not significantly blocked by F9K but was blocked with a combination of F9K and penton base. These results imply that the shorter length of fiber 9 (11 nm) relative to fiber 2 (37 nm) permits fiber-independent binding of Ad9 penton base to alpha(v)-integrins. The difference in fiber length may explain the different binding characteristics and tissue tropisms of each virus despite both utilizing the same fiber and penton base receptors.

Adenoviruses, Human↗

Fiber swap between adenovirus subgroups B and C alters intracellular trafficking of adenovirus gene transfer vectors.

Following receptor binding and internalization, intracellular trafficking of adenovirus (Ad) among subgroups B and C is different, with significant amounts of Ad serotype 7 (Ad7) (subgroup B) virions found in cytoplasm during the initial hours of infection while Ad5 (subgroup C) virions rapidly translocate to the nucleus. To evaluate the role of the fiber in these differences, we examined intracellular trafficking of Ad5, Ad7, and Ad5f7 (a chimeric vector composed of the Ad5 capsid with the fiber replaced by the Ad7 fiber) by conjugating Ad capsids directly with Cy3 fluorescent dye, permitting the trafficking of the capsids to be examined by fluorescence microscopy. The human lung carcinoma cell line A549 was infected with Cy3-conjugated viruses for 10 min followed by a 1-h incubation. Ad5 virions rapidly translocated to the nucleus (within 1 h of infection), while Ad7 virions were widely distributed in the cytoplasm at the same time point. Interestingly, chimeric Ad5f7 virions behaved similarly to Ad7 but not Ad5. In this regard, the percentages of nuclear localization of Ad5, Ad7, and Ad5f7 at 1 h following infection were 72% +/- 4%, 32% +/- 6%, and 38% +/- 2%, respectively. Consistent with these observations, fluorescence in situ hybridization demonstrated that most of the Ad5 DNA was detected at the nucleus after 1 h, but at the same time point, DNA of Ad7 and Ad5f7 was distributed in both the nucleus and cytoplasm. Quantification of the kinetics of Ad genomic DNA delivery to the nucleus using a fluorogenic probe-based PCR assay (TaqMan PCR) demonstrated that the percentages of nuclear association of Ad5 DNA and Ad5f7 DNA at 1 h postinfection were 80% +/- 13% and 43% +/- 1%, respectively. Although it has been generally accepted that Ad fiber protein mediates attachment of virions to cells and that fibers dissociate during endocytic uptake, these data suggest that in addition to mediating binding to the cell surface, fiber likely modulates intracellular trafficking as well.

Adenoviruses, Human↗

The level of expression of adenovirus type 2 transforming genes governs sensitivity to nonspecific immune cytolysis and other phenotypic properties of adenovirus 2-simian virus 40-transformed cell hybrids.

Syrian hamster embryo cells transformed by adenovirus type 2 (Ad2) or simian virus 40 (SV40) differ markedly in morphology, tumorigenicity, and susceptibility to in vitro lysis by nonspecific cytotoxic cells. Hybrid cells formed by fusing Ad2- and SV40-transformed Syrian hamster embryo cells may express only SV40 T antigens or both SV40 and Ad2 T antigens. Hybrids that express only SV40 T antigens are indistinguishable from the nonhybrid SV40-transformed phenotype, whereas hybrid cells that express T antigens from both viruses closely resemble the nonhybrid parental Ad2-transformed phenotype. Because these hybrid cells have been useful in the study of neoplastic transformation, we determined the amount of viral antigens that they accumulate in an attempt to correlate the level of expression of the transforming viral genes with some of their phenotypic properties. Hybrid cells that expressed proteins from both viruses showed reduced levels of SV40 T antigens compared with those of hybrid cells that did not express Ad2 T antigens. We also found that the production of several cellular proteins that influence cytomorphology was inhibited in hybrid and nonhybrid cells that expressed Ad2 T antigens, and the repression of these cellular proteins correlated with a change in cytomorphology from fibroblastic to spherical. Finally, we showed that the susceptibility of our hybrid cells to in vitro lysis by natural killer cells and activated macrophages, two putative host-effector cells involved in defense against neoplasia, correlated closely with the level of expression of a 58,000-dalton Ad2 protein. The results reported here, together with the results of previous studies, indicate that the oncogenic potential of hybrid cells that express both Ad2 and SV40 antigens is extremely sensitive to Ad2 expression, whereas other phenotypic properties depend on Ad2 expression in a dose-dependent manner.

Actins↗

Still's disease associated with adenovirus infection and defect in adenovirus directed natural killing.

Low natural killer (NK) activity towards adenovirus infected fibroblasts was detected in the peripheral blood of a child with Still's disease and was not normalised by the addition of interferon alfa or interleukin 2. NK cytotoxicity directed at K 562 target cells or polio infected fibroblasts was normal. This specific NK deficiency might have contributed to the development of the child's Still's disease.

Adenoviridae Infections↗

Restriction site mapping of adenovirus types 9 and 15 and genome types of intermediate adenovirus 15/H9.

Physical maps were established for seven genome types of the intermediate adenovirus (AV) 15/H9 and for the serologically related prototypes AV15 and 9 using the enzymes BamHI, BglII, and HindIII. The polarity of the fragment order was determined by hybridization with known AV2 fragments. AV15/H9 strains showed more restriction sites in common with AV9 than with AV15. The results are consistent with the hypothesis that intermediate AV15/H9 strains have emerged by recombination.

Adenoviruses, Human↗

Neutralizing antibodies to adenovirus serotype 5 vaccine vectors are directed primarily against the adenovirus hexon protein.

The utility of recombinant adenovirus serotype 5 (rAd5) vector-based vaccines for HIV-1 and other pathogens will likely be limited by the high prevalence of pre-existing Ad5-specific neutralizing Abs (NAbs) in human populations. However, the immunodominant targets of Ad5-specific NAbs in humans remain poorly characterized. In this study, we assess the titers and primary determinants of Ad5-specific NAbs in individuals from both the United States and the developing world. Importantly, median Ad5-specific NAb titers were >10-fold higher in sub-Saharan Africa compared with the United States. Moreover, hexon-specific NAb titers were 4- to 10-fold higher than fiber-specific NAb titers in these cohorts by virus neutralization assays using capsid chimeric viruses. We next performed adoptive transfer studies in mice to evaluate the functional capacity of hexon- and fiber-specific NAbs to suppress the immunogenicity of a prototype rAd5-Env vaccine. Hexon-specific NAbs were remarkably efficient at suppressing Env-specific immune responses elicited by the rAd5 vaccine. In contrast, fiber-specific NAbs exerted only minimal suppressive effects on rAd5 vaccine immunogenicity. These data demonstrate that functionally significant Ad5-specific NAbs are directed primarily against the Ad5 hexon protein in both humans and mice. These studies suggest a potential strategy for engineering novel Ad5 vectors to evade dominant Ad5-specific NAbs.

Adenoviruses, Human↗

Fiber knob modifications overcome low, heterogeneous expression of the coxsackievirus-adenovirus receptor that limits adenovirus gene transfer and oncolysis for human rhabdomyosarcoma cells.

Exploiting the lytic life cycle of viruses has gained recent attention as an anticancer strategy (oncolysis). To explore the utility of adenovirus (Ad)-mediated oncolysis for rhabdomyosarcoma (RMS), we tested RMS cell lines for Ad gene transduction and infection. RMS cells were variably transduced by Ad. Compared with control cells, RMS cells were less sensitive or even resistant to oncolysis by wild-type virus. RMS cells expressed the Ad internalization receptors, alpha(v) integrins, but had low or undetectable expression of the major attachment receptor, coxsackievirus-Ad receptor (CAR). Mutant Ads with ablated CAR binding exhibited only 5-20% of transgene expression in RMS cells seen with a wild-type vector, suggesting that residual or heterogeneous CAR expression mediated the little transduction that was detectable. Immunohistochemical analysis of archived clinical specimens showed little detectable CAR expression in five embryonal and eight alveolar RMS tumors. Stable transduction of the cDNA for CAR enabled both efficient Ad gene transfer and oncolysis for otherwise resistant RMS cells, suggesting that poor CAR expression is the limiting feature. Gene transfer to RMS cells was increased >2 logs using Ads engineered with modified fiber knobs containing either an integrin-binding RGD peptide or a polylysine peptide in the exposed HI loop. The RGD modification enabled increased oncolysis for RMS cells by a conditionally replicative Ad, Ad delta24RGD, harboring a retinoblastoma-binding mutation in the E1A gene. Thus, the development of replication-competent vectors targeted to cell surface receptors other than CAR is critical to advance the use of Ad for treating RMS.

Adenoviridae↗

Helper function of adenovirus 2 for adenovirus 41 antigen synthesis in semi-permissive and non-permissive cells.

Using a fluorescent focus assay, complementation and interference effects of Ad2 and Ad41 on each other in mixed infection were investigated. Ad2 provided a helper function for Ad41 late antigen synthesis in cells normally non-permissive for Ad41 growth (HEF cells), and enhanced Ad41 late antigen synthesis in semi-permissive Chang conjunctival cells. The degree of complementation by Ad2 was dependent on its input concentration. In addition, interference by Ad41 on Ad2 replication was seen in HEF cells. The degree of interference by Ad41 was dependent on the relative time of infection by each serotype. The complementation results in HEF cells suggest an absolute dependency of Ad41 on an adenovirus helper function in these cells. The results presented are consistent with the postulated helper function provided in trans by 293 cells, which are transformed by Ad5 early region 1.

Adenoviridae↗

Efficient gene transfer into normal human skeletal cells using recombinant adenovirus and conjugated adenovirus-DNA complexes.

In order to assess efficient DNA gene transfer into human primary cell cultures derived from the skeleton we tested two viral-based procedures. First, replication-deficient recombinant adenoviruses (ADV) were used to infect post-confluent human marrow stromal fibroblasts (HMSF) and human trabecular bone (HTB) cells. Both cell types were readily infected by modified adenoviral vectors carrying a reporter gene making this virus an attractive candidate to facilitate DNA gene transfer. In a second approach we coincubated DNA with ADV that had polylysine (PLL) covalently attached. With this ADV/PLL/DNA complex, very efficient gene transfer into multilayered HMSF and HTB cell cultures was observed, and DNA coincubated with unmodified ADV failed to be effectively transferred. These data imply that the covalently bound PLL more effectively binds exogenous DNA, resulting in a highly efficient internalization event in both cell types. Thus, this latter method has many advantages over conventional ADV gene transfer procedures. It is simple, rapid, and it does not require engineering of DNA into the viral genome, thereby allowing transfer of large fragments of DNA.

Adenoviridae↗

Endocytosis of adenovirus and adenovirus capsid proteins.

Key proteins of the icosahedral-shaped adenovirus (Ad) capsid mediate infection, and interact with cellular proteins to coordinate stepwise events of cell entry that produce successful gene transfer. Infection is mediated predominantly by the penton and fiber capsid proteins. The fiber initiates cell binding while the penton binds integrin coreceptors, triggering integrin-mediated endocytosis. Penton integrin signaling precedes viral escape from the endosomal vesicle. After cell binding, the virus undergoes stepwise disassembly of the capsid, shedding proteins during cell entry. Intracellular trafficking of the remaining capsid shell is mediated by the interaction of naked particles with the cytoskeleton. The capsid translocates toward the nucleus, with the majority of capsid proteins accumulating at the nuclear periphery, while viral DNA and associated protein VII are extruded through the nuclear pore. This discussion will encompass the current knowledge on Ad cell entry and trafficking, with an emphasis on the contribution of Ad capsid proteins to these processes. A greater understanding of the highly effective Ad cell entry pathway may lend itself to the development of safer drug and gene delivery alternatives utilizing similar pathways.

Adenoviridae↗

Nucleotide sequence of L1 and part of P1 of hexon gene of fowl adenovirus associated with hydropericardium hepatitis syndrome differs with the corresponding region of other fowl adenoviruses.

In order to study the serotypic variations in hydropericardium hepatitis syndrome (HHS) causing virus, the DNA was extracted from the purified virus, a 0.7 kb variable region of hexon gene encoding L1 and part of P1 amplified and sequenced. Both nucleotide and derived amino acid sequences, corresponding to the variable region, were compared with the published fowl adenovirus sequences (FAV serotypes 10, 1 and 8). As expected the 0.7 kb sequence showed single open reading frame (ORF). There was a nucleotide sequence variation of 8.2, 28.1 and 40.3%, respectively, with FAV serotypes 10, 1 and 8. The dendrogram constructed with the nucleotide sequences showed that HHS virus and FAV10 are closer to each other and are away to FAV1 and FAV8. However, the derived amino acid sequence showed variations as high as 28.8, 38 and 45.1% with FAV serotypes 10, 1 and 8, respectively. Such high degree variation has been found due to the shift in the reading frame caused by deletions indicating that the FAV4 associated with HHS is unique and different from FAV10. To the best of our knowledge this is the first report on nucleotide sequence analysis of hexon gene fragment of FAV4 associated with HHS.

Amino Acid Sequence↗

Adenovirus stripping: a versatile method to generate adenovirus vectors with new cell target specificity.

We developed a new type of adenovirus type 5 (Ad5)-derived vector with genetically modified fiber proteins whose knob domains could be stripped off due to the insertion of a single Factor Xa cleavage site in the fiber shaft, between a cellular ligand and the knob domain. This Ad vector did not require a specific cell line for propagation and could be grown in HEK-293 cells. Stripping off the knob domains removed the endogenous cell-binding moiety of Ad but retained the new cell ligand for retargeting purposes. As experimental models for cell ligands, we used two peptides with different sequence complexities: (i) the integrin-binding tripeptide RGD and (ii) a 58-residue oligopeptide termed affibody (Zwt). Zwt binds specifically to the human IgG1 Fc domain or to its Fc3(1) homolog. The modified fibers were efficiently encapsidated into virions, and the Factor Xa sites were fully accessible to proteolysis. In vitro binding assays using recombinant Fc3(1) protein and Ad5-mediated gene transduction of Fc3(1)-expressing cells demonstrated that the proteolytically deknobbed Ad5-Zwt vector was functional and specific for receptor targeting.

Adenoviridae↗

Binding modes of the precursor of adenovirus major core protein VII to DNA and template activating factor I: implication for the mechanism of remodeling of the adenovirus chromatin.

Template Activating Factor (TAF) I remodels the adenovirus (Ad) core structure composed of the Ad genome DNA and basic viral core proteins and stimulates in vitro DNA replication and transcription of the Ad core. We have recently reported that TAF-I binds to major core protein VII and forms DNA-protein VII-TAF-I ternary complexes in vitro and in vivo. Further to understand the mechanism of remodeling of the Ad core, we characterized the interaction mode between the precursor of protein VII (pre-VII) and either DNA or TAF-I by means of biochemical and biophysicochemical methods. We found that a major binding region of pre-VII with both DNA and the acidic carboxyl-terminal region of TAF-I lies in the arginine-rich region of pre-VII. Both amino-terminal and carboxyl-terminal regions of pre-VII without the arginine-rich region directly bound to DNA and supported the DNA binding activity of the arginine-rich region. A TAF-I mutant protein lacking the acidic carboxyl-terminal region bound preferentially to the carboxyl-terminal region of pre-VII containing the arginine-rich region rather than the amino-terminal region of pre-VII. Thus, DNA interacted with the entire region of pre-VII, while TAF-I bound preferentially to the carboxyl-terminal region of pre-VII. This binding mode suggests the formation of the ternary complexes among DNA, protein VII, and TAF-I. On the basis of the binding modes in binary systems, we discussed the remodeling mechanism of the Ad core in early phases of infection.

Adenoviridae↗

High levels of adenovirus DNA in serum correlate with fatal outcome of adenovirus infection in children after allogeneic stem-cell transplantation.

An increase in the incidence of adenovirus (AdV) infection leading to death among children who have undergone allogeneic stem-cell transplantation has made it necessary to find new ways to monitor AdV infection. In this retrospective study, levels of AdV DNA in serum samples obtained from 36 transplant recipients with stool cultures positive for AdV were measured by polymerase chain reaction (PCR) semiquantitatively by analyzing serial dilutions of the DNA template. Six (86%) of 7 children who died of AdV infection, compared with only 2 (7%) of 29 other patients, had high serum levels of AdV DNA (detectable by PCR at a > or =100-fold dilution of the DNA template; P<.0001). High serum levels of AdV DNA were reached a mean of 18 days before death (range, 6-29 days). Quantification of adenoviral DNA in serum may prove to be a valuable tool to diagnose and monitor AdV infection and disease in immunocompromised children.

Adenoviridae↗

Nucleotide sequence of the transforming early region E1b of adenovirus type 12 DNA: structure and gene organization, and comparison with those of adenovirus type 5 DNA.

The nucleotide sequence of the entire transforming early region of E1b of the highly oncogenic adenovirus type 12 (Ad12) DNA has been determined. The total sequence (3860 base pairs) encompasses the entire transforming early region E1 of Ad12 DNA. From the sequence for the E1b region of Ad12, and the transcription map of the E1b region (1, 2, 3, and this paper) the structure and gene organization of the early region E1b of Ad12 DNA were analyzed and compared with those of the E1b region in the non-oncogenic Ad5 DNA (4, 5). Most of the sequences in the E1b region of Ad12 was highly homologous to that of Ad5. It is predicted that the Ad12 region E1b codes for polypeptides of 53.9, 19.1, and 8.9 kd. This situation is identical with that of the Ad5 region E1b which codes for polypeptides of 54.9, 20.6, and 8.3 kd. The function of these predicted polypeptides encoded by the E1b regions in cell transformation is discussed.

Adenoviridae↗

Targeting of macrophage activity by adenovirus-mediated intragraft overexpression of TNFRp55-Ig, IL-12p40, and vIL-10 ameliorates adenovirus-mediated chronic graft injury, whereas stimulation of macrophages by overexpression of IFN-gamma accelerates chronic graft injury in a rat renal allograft model.

Adenovirus (Ad)-mediated gene transfer of immunoregulatory molecules prevents acute allograft rejection. It is here analyzed for the first time whether this approach may prevent the development of chronic renal allograft injury in rats. Renal allografts (F344-->Lewis rat) were ex vivo transduced in group I with control Ad-construct, group II with three different therapeutic Ad-constructs expressing the immunoregulatory molecules vIL-10, TNFRp55-Ig, and IL-12p40, and group III with AdIFN-gamma. Group IV served as untreated controls. Control grafts (IV) showed increasing proteinuria during the 24-wk follow-up. Chronic graft injury was accelerated by Ad-control (I) and even more by AdIFN-gamma (III). All rats carrying the AdIFN-gamma-transduced grafts died within 12 to 13 wk by advanced chronic renal failure associated with strong immune cell infiltration and immune gene expression. By contrast, the Ad-therapy group II showed less inflammation and improved graft histology and function if compared with the groups I and III. Moreover, significantly less infiltrating ED-1(+) macrophages and an improved histologic score even if compared with untreated controls (IV) was observed. However, after disappearance of therapeutic gene expression, group II showed increasing proteinuria probably as result of late T cell activation to the Ad-encoded proteins. Ex vivo transduction of allografts with Ad-control or even more AdIFN-gamma expression promotes intragraft inflammation and chronic graft injury. Targeting macrophage activation by a cocktail of therapeutic genes improved the results. These data support the pathogenetic role of cytokines in chronic graft injury; however, they also show the limitations of the Ad-mediated gene transfer.

Adenoviridae↗

The detection of an unidentified type of adenovirus in the stools of calves with weak calf syndrome by use of a commercial kit designed for the detection of human adenoviruses.

An outbreak of polyarthritis in newborn calves in a large collective dairy herd was characterized by intra-articular blood-tinged synoviae, blood tainted faeces and massive subcorneal haemorrhages. Faecal samples from eight clinical newborn cases, 10 from unrelated dairy farms and 10 faecal samples from healthy calves were examined by the Rida Quick rotavirus/adenovirus-combi test . A specific adenovirus antigen precipitin-line was seen in the reaction in all the faecal samples from the diseased calves (n = 8), while all the others (n = 20) were negative. In addition, the same positive reaction was noted when one aqueous humor and two synovial samples were tested with this kit. Several other enteropathogens were found sporadically, but no conclusive significance could be attributed to their presence. Bovine viral diarrhoea and infectious bovine rhinothracheitis viruses as well as Chlamydia spp. and Mycoplasma spp. were not involved in this episode.

Adenoviridae↗

Intracellular forms of Adenovirus DNA. II. Isolation in dye-buoyant density gradients of a DNA-RNA complex from KB cells infected with Adenovirus type 2.

DNA-RNA complexes with different DNA/RNA ratios have been isolated from KB cells productively infected with human adenovirus type 2 by the dye-buoyant density procedure by using propidium iodide. Both the DNA and RNA components of these complexes are virus specific, and parental as well as newly synthesized viral DNA can be recovered from these complexes. The RNA component is susceptible to digestion with pancreatic ribonuclease at low and high salt concentrations. The RNA is in part liberated from the complex during purification over several cycles of equilibrium centrifugation in dye-buoyant density and Cs(2)SO(4) gradients. Analysis in the latter gradients reveals at least four classes of virus-specific nucleic acid: (i) RNA loosely bound and released during purification, (ii) and (iii) two distinct classes of RNA-DNA complexes with different DNA/RNA ratios, and (iv) DNA apparently not associated with RNA. The size of the RNA molecules is large but varying in the different classes of complexes. The biological function of these complexes is still uncertain, but they may be transcription complexes.

Adenoviridae↗