Adenoviruses in the immunocompromised host

Infection kinetics of human adenovirus serotype 41 in HEK 293 cells

The purpose of this work was to acquire an overview of the infectious cycle of HAdV-41 in permissive HEK 293 cells and compare it to that observed with the prototype of the genus, Human adenovirus C HAdV-2. HEK 293 cells were infected with each virus separately and were harvested every 12 h for seven days. Infection kinetics were analysed using confocal and electronic microscopy. The results show that, when properly cultivated, HAdV-41 was not fastidious. It had a longer multiplication cycle, which resulted in the release of complete viral particles and viral stocks reached high titres. After 60 h of infection, the export of viral proteins from the infected cell to the extracellular milieu was observed, with a pattern similar to that previously described for HAdV-2 penton-base trafficking after 30 h of infection. HAdV-41 had a non-lytic cycle and the infection spread from the first infected cell to its neighbours. The release process of the viral particles is unknown. The results observed for HAdV-41 infection in HEK 293 cells show how different this virus is from the prototype HAdV-2 and provides information for the development of this vector for use in gene therapy.

An interesting case of adenoviral hepatitis in a cardiac transplant recipient

Adenoviral infections are commonly described in pediatric transplant populations. However, much less information is available regarding the incidence of infection and clinical spectrum of disease in adult transplant recipients. Moreover, this infection usually manifests as involvement of the transplanted organ in one pathologic form or the other, in addition to other systemic manifestations. We present a case of adenoviral infection of a nontransplanted organ in a solid organ transplant recipient.

Disseminated adenovirus infection in renal transplant recipients: the role of cidofovir and intravenous immunoglobulin

Disseminated adenovirus (ADV) infection in solid organ transplant patients is associated with high mortality. Limited studies have shown benefit from using cidofovir (CDV), as well as intravenous immunoglobulin (IVIG). In this study, we report 2 renal transplant patients who presented with fever and pulmonary infiltrates. Both patients continued to worsen despite antibiotic therapy. Bronchoalveolar lavage viral culture and serum polymerase chain reaction (PCR) were positive for ADV. Patients were treated with CDV, IVIG, and reduction in immunosuppression. A progressive decline in serum ADV DNA by PCR correlated with clinical improvement and pulmonary infiltrates improved. Both patients recovered. Allograft function was preserved although reversible acute kidney injury was observed in both patients. To the best of our knowledge, this is the first successful use of CDV and IVIG in renal transplant patients with disseminated ADV infection.

Detection of opportunistic DNA viral infections by multiplex PCR among HIV infected individuals receiving care at a tertiary care hospital in South India

PURPOSE

Opportunistic viral infections cause increased morbidity and mortality among human immunodeficiency virus (HIV) infected individuals, especially those who are not on antiretroviral treatment. Early diagnosis of these opportunistic viruses will be able to reduce the risk of disease progression with appropriate intervention.

MATERIALS AND METHODS

Multiplex PCR was attempted to detect the opportunistic herpes viruses (HSV-1, HSV-2, VZV, EBV, and CMV), adenovirus and polyoma viruses (JC and BK) in three cocktails of PCR reactions. Subsequently, all the viruses detected were quantitated by testing using monoplex real time PCR. Whole blood samples collected between 2006 and 2007 from 68 treatment naïve HIV-1 infected and 30 normal healthy individuals were tested for these eight viruses. Among the 68 HIV-1 infected individuals 35 had CD4+ T cell count less than or equal to 200 while the other 33 had greater than 200 CD4+ T cells.

RESULTS

Among the 68 HIV-1 infected individuals, 49 (72%) were positive for EBV, 5 (7%) samples were positive for CMV. All the five CMV positive individuals had CD4+ T cell count of less than or equal to 200 cells/microL. The mean EBV load among the individuals with a CD4+ T cells of less than or equal to 200 cells/microL was 3.88 log(10) while among those with greater than 200 CD4+ T cells it was 3.75 log(10) . The mean CMV load was 6.98 log(10). Three samples were positive for both CMV & EBV. None of the samples was positive for HSV-1, HSV-2, VZV, Adenovirus, JC and BK viruses.

CONCLUSIONS

In our study, multiplex PCR based detection system was found useful in detecting opportunistic viruses in HIV infected individuals. Though EBV is the most prevalent opportunistic viral infection among HIV infected individuals, there was no significant association between EBV load, CD4+ T cell counts and HIV-1 virus load. CMV was seen in HIV infected individuals with low CD4+ T cell counts (less than 200 cells/microL).

Isolation and characterization of adenoviruses persistently shed from the gastrointestinal tract of non-human primates

Adenoviruses are important human pathogens that have been developed as vectors for gene therapies and genetic vaccines. Previous studies indicated that human infections with adenoviruses are self-limiting in immunocompetent hosts with evidence of some persistence in adenoid tissue. We sought to better understand the natural history of adenovirus infections in various non-human primates and discovered that healthy populations of great apes (chimpanzees, bonobos, gorillas, and orangutans) and macaques shed substantial quantities of infectious adenoviruses in stool. Shedding in stools from asymptomatic humans was found to be much less frequent, comparable to frequencies reported before. We purified and fully sequenced 30 novel adenoviruses from apes and 3 novel adenoviruses from macaques. Analyses of the new ape adenovirus sequences (as well as the 4 chimpanzee adenovirus sequences we have previously reported) together with 22 complete adenovirus genomes available from GenBank revealed that (a) the ape adenoviruses could clearly be classified into species corresponding to human adenovirus species B, C, and E, (b) there was evidence for intraspecies recombination between adenoviruses, and (c) the high degree of phylogenetic relatedness of adenoviruses across their various primate hosts provided evidence for cross species transmission events to have occurred in the natural history of B and E viruses. The high degree of asymptomatic shedding of live adenovirus in non-human primates and evidence for zoonotic transmissions warrants caution for primate handling and housing. Furthermore, the presence of persistent and/or latent adenovirus infections in the gut should be considered in the design and interpretation of human and non-human primate studies with adenovirus vectors.

Molecular modeling and epitopes mapping of human adenovirus type 3 hexon protein

The hexon protein of human adenovirus (HAdV) processes type-specific B-cell neutralizing epitopes. We developed a new effective, reliable approach to map these epitopes on hexon protein of HAdVs. A three-dimensional (3D) model of the HAdV3 hexon was obtained by homology modeling and refined by molecular mechanics and molecular dynamics simulations. A modified evolutionary trace (ET) analysis called reverse ET (RET) was used to predict the type-specific B-cell neutralizing epitopes. An epitope-screening algorithm based on analyzing the solvent accessibility surface (SAS) area from the 3D model and calculation of sites homology using RET was designed and implemented in the BioPerl script language. Five epitope polypeptide segments were predicted and mapped onto the 3D model. Finally five polypeptides were synthesized and the predicted epitopes were identified by enzyme-linked immunosorbent assay (ELISA) and Neutralization Test (NT). It was found that the type-specific neutralizing epitopes of HAdV3 are located at the top surface of hexon tower regions (residue numbers: 135-146, 169-178, 237-251, 262-272, 420-434). This work is of great significance to the molecular design of a multivalent HAdVs vaccine.

Safety and tolerability of cidofovir in high-risk pediatric patients

Adenovirus (ADV) infection is a serious complication after hematopoietic stem cell transplantation with significant morbidity and mortality. Cidofovir has emerged as the primary therapy for ADV infection, but its use has been limited by concerns of nephrotoxicity. We report the safety and tolerability of 234 cidofovir infusions in 23 patients at a single institution, and demonstrate evidence of acceptable nephrotoxicity despite concomitant use of other nephrotoxic agents. Three patients suffered adverse events, two related to the hydration regimen associated with cidofovir administration. We conclude that cidofovir is a safe and mostly well tolerated drug in a high-risk pediatric population.

Coagulation factors IX and X enhance binding and infection of adenovirus types 5 and 31 in human epithelial cells

Most adenoviruses bind directly to the coxsackie and adenovirus receptor (CAR) on target cells in vitro, but recent research has shown that adenoviruses can also use soluble components in body fluids for indirect binding to target cells. These mechanisms have been identified upon addressing the questions of how to de- and retarget adenovirus-based vectors for human gene and cancer therapy, but the newly identified mechanisms also suggest that the role of body fluids and their components may also be of importance for natural, primary infections. Here we demonstrate that plasma, saliva, and tear fluid promote binding and infection of adenovirus type 5 (Ad5) in respiratory and ocular epithelial cells, which corresponds to the natural tropism of most adenoviruses, and that plasma promotes infection by Ad31. By using a set of binding and infection experiments, we also found that Ad5 and Ad31 require coagulation factors IX (FIX) or X (FX) or just FIX, respectively, for efficient binding and infection. The concentrations of these factors that were required for maximum binding were 1/100th of the physiological concentrations. Preincubation of virions with heparin or pretreatment of cells with heparinase I indicated that the role of cell surface heparan sulfate during FIX- and FX-mediated adenovirus binding and infection is mechanistically serotype specific. We conclude that the use of coagulation factors by adenoviruses may be of importance not only for the liver tropism seen when administering adenovirus vectors to the circulation but also during primary infections by wild-type viruses of their natural target cell types.

The cell adhesion molecule "CAR" and sialic acid on human erythrocytes influence adenovirus in vivo biodistribution

Although it has been known for 50 years that adenoviruses (Ads) interact with erythrocytes ex vivo, the molecular and structural basis for this interaction, which has been serendipitously exploited for diagnostic tests, is unknown. In this study, we characterized the interaction between erythrocytes and unrelated Ad serotypes, human 5 (HAd5) and 37 (HAd37), and canine 2 (CAV-2). While these serotypes agglutinate human erythrocytes, they use different receptors, have different tropisms and/or infect different species. Using molecular, biochemical, structural and transgenic animal-based analyses, we found that the primary erythrocyte interaction domain for HAd37 is its sialic acid binding site, while CAV-2 binding depends on at least three factors: electrostatic interactions, sialic acid binding and, unexpectedly, binding to the coxsackievirus and adenovirus receptor (CAR) on human erythrocytes. We show that the presence of CAR on erythrocytes leads to prolonged in vivo blood half-life and significantly reduced liver infection when a CAR-tropic Ad is injected intravenously. This study provides i) a molecular and structural rationale for Ad-erythrocyte interactions, ii) a basis to improve vector-mediated gene transfer and iii) a mechanism that may explain the biodistribution and pathogenic inconsistencies found between human and animal models.

Waterborne adenovirus

Adenoviruses are associated with numerous disease outbreaks, particularly those involving d-cares, schools, children's camps, hospitals and other health care centers, and military settings. In addition, adenoviruses have been responsible for many recreational water outbreaks, including a great number of swimming pool outbreaks than any other waterborne virus (Gerba and Enriquez 1997). Two drinking water outbreaks have been documented for adenovirus (Divizia et al. 2004; Kukkula et al. 1997) but none for food. Of the 51 known adenovirus serotypes, one third are associated with human disease, while other infections are asymptomatic. Human disease associated with adenovirus infections include gastroenteritis, respiratory infections, eye infections, acute hemorrhagic cystitis, and meningoencephalitis (Table 2). Children and the immunocompromised are more severely impacted by adenovirus infections. Subsequently, adenovirus is included in the EPA's Drinking Water Contaminant Candidate List (CCL), which is a list of unregulated contaminants found in public water systems that may pose a risk to public health (National Research Council 1999). Adenoviruses have been detected in various waters worldwide including wastewater, river water, oceans, and swimming pools (Hurst et al. 1988; Irving and Smith 1981; Pina et al. 1998). Adenoviruses typically outnumber the enteroviruses, when both are detected in surface waters. Chapron et al. (2000) found that 38% of 29 surface water samples were positive for infectious Ad40 and Ad41. Data are lacking regarding the occurrence of adenovirus in water in the US, particularly for groundwater and drinking water. Studies have shown, however, that adenoviruses survive longer in water than enteroviruses and hepatitis A virus (Enriquez et al. 1995), which may be due to their double-stranded DNA. Risk assessments have been conducted on waterborne adenovirus (Crabtree et al. 1997; van Heerden et al. 2005c). Using dose-response data for inhalation from Couch et al. (1966), human health risks of infection, illness and death have been determined for various adenovirus exposures. Crabtree et al. (1997) conclude that, even at an adenovirus concentration of 1 per 1,000 L of drinking water, annual risks of infection exceed the suggested risk recommendation of 1 x 10(-4) per yr (Regli et al. 1991) (Table 8). Using the same exposure and dose-response assumptions, van Heerden et al. (2005c) determined annual risks of infection to be 1-1.7 x 10(-1) for two drinking water samples from South Africa containing 1.40 and 2.45 adenoviruses per 10,000 L, respectively. This present study estimated annual risks of infection associated with varying levels of adenoviruses per 100 L (Table 9). By assuming a 2 L/d exposure and utilizing the exponential model at r = 0.4172 (Haas et al. 1993), yearly risks exceed the risk recommendation of 1 x 10(-4) at every exposure level. There are limited data regarding the removal of adenoviruses by conventional water treatment or other physical-chemical treatment processes, but studies do suggest that adenoviruses are of equal or greater sensitivity to oxidizing disinfectants, when compared to waterborne viruses (the most resistant to ultraviolet light). Data suggest that the chlorine doses applied to control other waterborne viruses are more effective against adenovirus, resulting in a greater than 4-log10 removal of adenoviruses by conventional treatment and chlorination. If treatment can achieve a 4-log10 removal of adenoviruses, then, based on the risk levels presented in Table 9, surface water concentrations should not exceed 0.5 adenoviruses per 100 L (Fig. 2). More data are needed regarding effectiveness of water treatment against adenovirus and the human-virus dose-response relationship to fully understand the role of adenovirus as a waterborne public health threat.

Viruses

Viral infections are an important and often unrecognized component of disease in immunocompromised patients. The diagnosis and management of viral infections have expanded largely because of new quantitative molecular diagnostic assays. Well-recognized pathogens such as herpes simplex virus (HSV), cytomegalovirus (CMV), and respiratory viruses have been joined by newly recognized pathogens such as BK virus, human herpesvirus-6 (HHV-6), and human metapneumovirus in this highly susceptible patient population. The role of Epstein-Barr virus (EBV) and Human herpesvirus-8 (HHV-8) in lymphoproliferative diseases also continue to be clarified. As a result, the management of viral infections in patients with hematologic malignancies continues to be a growing challenge for the clinician.

Latent species C adenoviruses in human tonsil tissues

Although species C human adenoviruses establish persistent infections, the molecular details of this lifestyle remain poorly understood. We previously reported that adenovirus DNA is found in human mucosal T lymphocytes in a noninfectious form (C. T. Garnett, D. Erdman, W. Xu, and L. R. Gooding, J. Virol. 76:10608-10616, 2002). In this study, human tonsil and adenoid tissues were analyzed to determine the dynamics of infection, the rate of clearance of viral DNA, and the possibility of reactivation of virus from these tissues. The presence of viral DNA peaked at 4 years of age and declined thereafter. The average number of viral genomes declined with the age of the donor. The frequency of virus-bearing cells ranged from 3 x 10(-7) to 3.4 x 10(-4), while the amount of viral DNA per cell varied less, with an average of 280 copies per cell. All species C serotypes were represented in these tissues, although adenovirus type 6 was notably rare. Infectious virus was detected infrequently (13 of 94 of donors tested), even among donors with the highest levels of adenoviral DNA. Adenovirus transcripts were rarely detected in uncultured lymphocytes (2 of 12 donors) but appeared following stimulation and culture (11 of 13 donors). Viral DNA replication could be stimulated in most donor samples by lymphocyte stimulation in culture. New infectious virus was detected in 13 of 15 donors following in vitro stimulation. These data suggest that species C adenoviruses can establish latent infections in mucosal lymphocytes and that stimulation of these cells can cause viral reactivation resulting in RNA transcription, DNA replication, and infectious virus production.

Clinical features and treatment of adenovirus infections

Adenoviruses (Ads) are common opportunistic pathogens that are rarely associated with severe clinical symptoms in healthy individuals. In contrast, in patients with compromised immunity, Ad infections often result in disseminated and potentially life-threatening disease. Among these are AIDS patients, individuals with hereditary immunodeficiencies and recipients of solid organ or haematopoietic stem cell transplants (HSCT) who receive immunosuppressive therapy. The latter account for the largest number of severe Ad infections. There is currently no formally approved antiviral therapy for the treatment of severe Ad keratoconjunctivitis and life-threatening Ad infections in immunocompromised patients. Here we update current knowledge on Ad biology, the clinical features observed in different patient groups and specific immune responses towards Ad infections. In addition, we review current and future treatment options, including: (i) the antiviral drugs cidofovir, ribavirin and new investigational compounds, as evaluated in the clinic or in relevant animal models, as well as (ii) novel immunotherapeutic strategies.

Detection of respiratory viruses by molecular methods

SUMMARY

Clinical laboratories historically diagnose seven or eight respiratory virus infections using a combination of techniques including enzyme immunoassay, direct fluorescent antibody staining, cell culture, and nucleic acid amplification tests. With the discovery of six new respiratory viruses since 2000, laboratories are faced with the challenge of detecting up to 19 different viruses that cause acute respiratory disease of both the upper and lower respiratory tracts. The application of nucleic acid amplification technology, particularly multiplex PCR coupled with fluidic or fixed microarrays, provides an important new approach for the detection of multiple respiratory viruses in a single test. These multiplex amplification tests provide a sensitive and comprehensive approach for the diagnosis of respiratory tract infections in individual hospitalized patients and the identification of the etiological agent in outbreaks of respiratory tract infection in the community. This review describes the molecular methods used to detect respiratory viruses and discusses the contribution that molecular testing, especially multiplex PCR, has made to our ability to detect respiratory viruses and to increase our understanding of the roles of various viral agents in acute respiratory disease.

Adenoviruses in immunocompromised hosts

SUMMARY

The number of patients with acquired immunodeficiency has grown steadily as a result of both a larger number of patients receiving solid organ and hematopoietic stem cell transplants and their longer survival times. The use of newer, more potent immunosuppressive regimens has increased the frequency of severe adenovirus infections. Human adenoviruses are a large group of viruses, represented by at least 52 serotypes with various genotypes divided into genomic clusters, and these may cause a broad variety of clinical manifestations. The development of molecular methods has increased the sensitivity and rapidity of adenovirus infection diagnosis. The implementation of PCR assays has significantly contributed to the identification of patients with disseminated adenovirus disease. More recently, the development of real-time PCR assays has permitted virus quantification and patient follow-up. There is no treatment for adenovirus with demonstrated efficacy, although cidofovir is widely used. Sensitive diagnostic tests for adenovirus can contribute to the early diagnosis and successful treatment of life-threatening adenovirus infections, especially in complex immunocompromised patients. The development of improved adenovirus therapy still remains a challenge. Adenovirus genetic diversity should be considered for diagnosis, typing, and therapeutic interventions.

Development and evaluation of a novel gene delivery vehicle composed of adenovirus serotype 35

The capacity of gene delivery vehicles is considered to be a critical factor determining the success of gene therapy. To date, various types of gene delivery vehicle have been developed. Among them, recombinant adeno-virus (Ad) vectors have potential that has favored their worldwide use in vitro and in vivo. Conventional Ad vectors are composed of subgroup C Ad serotype 5 (Ad5), although it has been clarified that the drawbacks of Ad5 vectors are a high seroprevalence of Ad5 in adults and low transduction efficiencies in cells lacking the primary receptor for Ad5, coxsackievirus and adenovirus receptor. To overcome these problems, we developed a novel Ad vector fully composed of Ad serotype 35 (Ad35). Ad35 vectors show a wide tropism for human cells because Ad35 binds to human CD46, which is ubiquitously expressed on almost all human cells, as a primary receptor. In addition, anti-Ad5 antibodies do not inhibit Ad35 vector-mediated transduction and the seroprevalence of Ad35 in adults is lower than that of Ad5. This paper reviews our studies on the development and evaluation of Ad35 vectors. Ad vectors derived from other Ad serotypes different from Ad5, including Ad35, are expected to be gene delivery vehicles alternative to conventional Ad5 vectors.

Viruses as co-factors for the initiation or exacerbation of lung fibrosis

Idiopathic pulmonary fibrosis (IPF) remains exactly that. The disease originates from an unknown cause, and little is known about the mechanisms of pathogenesis. While the disease is likely multi-factorial, evidence is accumulating to implicate viruses as co-factors (either as initiating or exacerbating agents) of fibrotic lung disease. This review summarizes the available clinical and experimental observations that form the basis for the hypothesis that viral infections may augment fibrotic responses. We review the data suggesting a link between hepatitis C virus, adenovirus, human cytomegalovirus and, in particular, the Epstein-Barr gammaherpesvirus, in IPF. In addition, we highlight the recent associations made between gammaherpesvirus infection and lung fibrosis in horses and discuss the various murine models that have been used to investigate the contribution of gammaherpesviruses to fibrotic progression. We review the work demonstrating that gammaherpesvirus infection of Th2-biased mice leads to multi-organ fibrosis and highlight studies showing that gammaherpesviral infections of mice either pre- or post-fibrotic challenge can augment the development of fibrosis. Finally, we discuss potential mechanisms whereby viral infections may amplify the development of fibrosis. While none of these studies prove causality, we believe the evidence suggests that viral infections should be considered as potential initiators or exacerbating agents in at least some cases of IPF and thereby justify further study.

Retrospective study of adenovirus in autopsied pulmonary tissue of pediatric fatal pneumonia in South China

Background

Adenovirus are the important pathogen of pediatric severe pneumonia. The aim of this study is to analyze the infection, subtype and distribution of adenovirus in autopsied pulmonary tissue of fatal pneumonia in infants and children, and the relationships between adenovirus infection and respiratory illness in South China.

Methods

Nested PCR was performed on DNA extracted from autopsied lung tissue from patients who died of severe pneumonia, and the positive nested PCR products were cloned and sequenced. The adenovirus in autopsied pulmonary tissue was also analyzed by immunohistochemistry assay in a blind way.

Results

In the 175 autopsied pulmonary tissues, the positive percentage of adenovirus was 9.14% (16/175) and 2.29% (4/175) detected with nested PCR and immunohistochemistry, respectively. There are three cases of adenovirus serotype 3, twelve cases of adenovirus serotype 4 and one case of serotype 41 determined by sequencing of the cloned positive nested PCR products.

Conclusion

Adenovirus is an important cause of severe pneumonia, and these data suggest that adenovirus serotype 4 might be an important pathogen responsible for the fatal pneumonia in Guangzhou, South China.

Adenovirus serotype 35 vector-mediated transduction following direct administration into organs of nonhuman primates

Adenovirus (Ad) serotype 35 (Ad35) vectors have attracted remarkable attention as alternatives to conventional Ad serotype 5 (Ad5) vectors. In a previous study, we showed that intravenously administered Ad35 vectors exhibited a safer profile than Ad5 vectors in cynomolgus monkeys, which ubiquitously express CD46, an Ad35 receptor, in a pattern similar to that in humans. However, the Ad35 vectors poorly transduced the organs. In this study, we examined the transduction properties of Ad35 vectors after local administration into organs of cynomolgus monkeys. The vectors transduced different types of cells depending on the organ. Hepatocytes and microglia were mainly transduced after the vectors were injected into the liver and cerebrum, respectively. Injection of the vectors into the femoral muscle resulted in the transduction of cells that appeared to be fibroblasts and/or macrophages. Conjunctival epithelial cells showed transgene expression following infusion into the vitreous body of the eyeball. Transgene expression was limited to areas around the injection points in most of the organs. In contrast, Ad35 vector-mediated transgene expression was not detected in any of the organs not injected with Ad35 vectors. These results suggest that Ad35 vectors are suitable for gene delivery by direct administration to organs.

Development of multiplexed real-time quantitative polymerase chain reaction assay for detecting human adenoviruses

Adenoviruses (AdVs) have been associated with a wide variety of human disease and are increasingly recognized as viral pathogens that can cause significant morbidity and mortality in immunocompromised patients. Early detection of AdV DNA in plasma and sterile fluids has been shown to be useful for identifying patients at risk for invasive AdV disease. Because of the large number of existing Adv types, few real-time quantitative AdV polymerase chain reaction (PCR) assays published effectively cover all AdV types. We designed a series of AdV PCR primers and probes and empirically multiplexed them into 2 separate real-time PCR assays to quantitatively detect all 49 serotypes of human AdV (types 1-49) available from American Type Culture Collection. We then subsequently multiplexed all the primers and probes into 1 reaction. The sensitivity of these assays was determined to be less than 10 copies per reaction (500 copies/mL plasma). In a retrospective evaluation, we detected all 84 clinical AdV isolates isolated in cell culture from patients undergoing hematopoietic stem cell transplantation between 1981 and 1987. Prospective analysis of 46 consecutive clinical samples submitted for AdV testing showed greater sensitivity and equal specificity of the AdV PCR than viral culture. This real-time PCR assay allows rapid, sensitive, and specific quantification of all currently defined AdVs into either 2 or 1 multiplex assay for clinical samples.

A case of necrotizing enterocolitis associated with adenovirus infection in a term infant with 22q11 deletion syndrome

Infections with adenoviruses are a common problem in the pediatric population. Normally asymptomatic to mild, those infections tend to take a more severe course in immunocompromised patients. 22q11 deletion syndrome (22q11DS) represents a common genetic disorder causing immunodeficiency from thymic hypoplasia or aplasia, heart defects, a characteristic facial appearance, and velopharyngeal dysfunction. Necrotizing enterocolitis (NEC) is a frequent gastrointestinal emergency observed in neonatal intensive care units. The occurrence of NEC is more prevalent in preterm infants. However, there are cases in term infants, but usually, they are associated with predisposing disorders. In this case report, a child is presented with 22q11DS that postnatally developed NEC associated with an adenoviral infection. Although other viruses such as toroviruses or cytomegaloviruses have been implicated in the pathogenesis of NEC in preterm infants, we could not find any report in the recent medical literature describing an association between adenoviral infections, NEC, and 22q11DS in a term infant.

A case report of adenovirus-related acute interstitial nephritis in a patient with AIDS

In immunosuppressed individuals, such as hematopoietic stem cell transplant recipients, adenoviruses (ADVs) are a well-known cause of morbidity and mortality, with limited treatment options. However, only a few cases were reported in patients with acquired immunodeficiency syndrome (AIDS), and little is known about the relevance of such an infection in these patients with many other concomitant opportunistic infections. We report the case of a 34-year-old man with AIDS presenting with gross hematuria, right flank pain, and acute decrease in kidney function superimposed on chronic kidney disease. His CD4 count was 0/muL despite highly active antiretroviral therapy. A computed tomographic scan showed enlargement of the right renal pelvis. Cystoscopy showed no clots or macroscopic lesions. Urine analysis showed no bacteria or abnormal epithelial cells. ADV was found in viral culture and by using real-time polymerase chain reaction in the patient's urine and later in blood. The renal biopsy specimen showed ADV-related tubulointerstitial nephritis with intranuclear inclusions in tubular cells stained by anti-ADV antibodies, in addition to chronic tubular and vascular changes. The ADV serotype belonged to subgroup B. Cidofovir therapy was contraindicated for this patient; therefore, he was administered intravenous ribavirin. The efficiency of this treatment could not be assessed because he rapidly developed neutropenia and disseminated aspergillosis and died. This case illustrates another cause of acute kidney disease in very immunosuppressed patients with AIDS, probably underdiagnosed.

Growth characteristics of human adenoviruses on porcine cell lines

Human adenoviruses (hAdV) have been recognized as a highly prevalent virus family causing severe disease in immunocompromised patients. In xenotransplantation the xenograft therefore will be exposed to these viruses, which in case of its infection might contribute to posttransplant complications. To evaluate the susceptibility of porcine cells for hAdV, we infected the porcine cell line POEK with seven serotypes representing all six hAdV species. Additionally, a second porcine cell line (ST) was infected with two serotypes. Viral replication of serotypes varied: porcine cells were fully permissive for serotypes 1, 4 and 17, semi-permissive for 11 and 21, and non-permissive for 31 and 40. Furthermore, we demonstrated the interaction of serotype 1 with the porcine homologue of the coxsackie-adenovirus receptor, the receptor used by many hAdV serotypes for cell attachment. Thus, various adenovirus types of different hAdV species may be capable of infecting different porcine tissue types.

Risk of waterborne illness via drinking water in the United States

Outbreaks of disease attributable to drinking water are not common in the U.S., but they do still occur and can lead to serious acute, chronic, or sometimes fatal health consequences, particularly in sensitive and immunocompromised populations. From 1971 to 2002, there were 764 documented waterborne outbreaks associated with drinking water, resulting in 575,457 cases of illness and 79 deaths (Blackburn et al. 2004; Calderon 2004); however, the true impact of disease is estimated to be much higher. If properly applied, current protocols in municipal water treatment are effective at eliminating pathogens from water. However, inadequate, interrupted, or intermittent treatment has repeatedly been associated with waterborne disease outbreaks. Contamination is not evenly distributed but rather affected by the number of pathogens in the source water, the age of the distribution system, the quality of the delivered water, and climatic events that can tax treatment plant operations. Private water supplies are not regulated by the USEPA and are generally not treated or monitored, although very few of the municipal systems involved in documented outbreaks exceeded the USEPA's total coliform standard in the preceding 12 mon (Craun et al. 2002). We provide here estimates of waterborne infection and illness risks in the U.S. based on the total number of water systems, source water type, and total populations exposed. Furthermore, we evaluated all possible illnesses associated with the microbial infection and not just gastroenteritis. Our results indicate that 10.7 M infections/yr and 5.4 M illnesses/yr occur in populations served by community groundwater systems; 2.2 M infections/yr and 1.1 M illnesses/yr occur in noncommunity groundwater systems; and 26.0 M infections/yr and 13.0 M illnesses/yr occur in municipal surface water systems. The total estimated number of waterborne illnesses/yr in the U.S. is therefore estimated to be 19.5 M/yr. Others have recently estimated waterborne illness rates of 12M cases/yr (Colford et al. 2006) and 16 M cases/yr (Messner et al. 2006), yet our estimate considers all health outcomes associated with exposure to pathogens in drinking water rather than only gastrointestinal illness. Drinking water outbreaks exemplify known breaches in municipal water treatment and distribution processes and the failure of regulatory requirements to ensure water that is free of human pathogens. Water purification technologies applied at the point-of-use (POU) can be effective for limiting the effects of source water contamination, treatment plant inadequacies, minor intrusions in the distribution system, or deliberate posttreatment acts (i.e., bioterrorism). Epidemiological studies are conflicting on the benefits of POU water treatment. One prospective intervention study found that consumers of reverse-osmosis (POU) filtered water had 20%-35% less gastrointestinal illnesses than those consuming regular tap water, with an excess of 14% of illness due to contaminants introduced in the distribution system (Payment 1991, 1997). Two other studies using randomized, blinded, controlled trials determined that the risks were equal among groups supplied with POU-treated water compared to untreated tap water (Hellard et al. 2001; Colford et al. 2003). For immunocompromised populations, POU water treatment devices are recommended by the CDC and USEPA as one treatment option for reducing risks of Cryptosporidium and other types of infectious agents transmitted by drinking water. Other populations, including those experiencing "normal" life stages such as pregnancy, or those very young or very old, might also benefit from the utilization of additional water treatment options beyond the current multibarrier approach of municipal water treatment.

Viral Infections of the Lung

The lungs are among the most vulnerable to microbial assault of all organs in the body. From a contemporary vantage, lower respiratory tract infections are the greatest cause of infection-related mortality in the United States, and rank seventh among all causes of deaths in the United States.2,3 From a global and historic perspective, the scope and scale of lower respiratory tract infection is greater than any other infectious syndrome, and viral pneumonias have proven to be some of the most lethal and dramatic of human diseases. The 1918–1919 influenza pandemic, perhaps the most devastating infectious disease pandemic in recorded history, resulted in an estimated 40 million deaths worldwide, including 700,000 deaths in the U.S.4 The global outbreak of severe acute respiratory syndrome (SARS) during 2003, although considerably smaller in scale, resulted in 8098 cases and 774 deaths5 and is a dramatic contemporary example of the ability of viral pneumonias to rapidly disseminate and cause severe disease in human populations.

Identification of CD46 binding sites within the adenovirus serotype 35 fiber knob

Species B human adenoviruses (Ads) are often associated with fatal illnesses in immunocompromised individuals. Recently, species B Ads, most of which use the ubiquitously expressed complement regulatory protein CD46 as a primary attachment receptor, have gained interest for use as gene therapy vectors. In this study, we focused on species B Ad serotype 35 (Ad35), whose trimeric fiber knob domain binds to three CD46 molecules with a KD (equilibrium dissociation constant) of 15.5 nM. To study the Ad35 knob-CD46 interaction, we generated an expression library of Ad35 knobs with random mutations and screened it for CD46 binding. We identified four critical residues (Phe242, Arg279, Ser282, and Glu302) which, when mutated, ablated Ad35 knob binding to CD46 without affecting knob trimerization. The functional importance of the identified residues was validated in surface plasmon resonance and competition binding studies. To model the Ad35 knob-CD46 interaction, we resolved the Ad35 knob structure at 2-A resolution by X-ray crystallography and overlaid it onto the existing structure for Ad11-CD46 interaction. According to our model, all identified Ad35 residues are in regions that interact with CD46, whereby one CD46 molecule binds between two knob monomers. This mode of interaction might have potential consequences for CD46 signaling and intracellular trafficking of Ad35. Our findings are also fundamental for better characterization of species B Ads and design of antiviral drugs, as well as for application of species B Ads as in vivo and in vitro gene transfer vectors.

Preclinical assessment of FHIT gene replacement therapy in human leukemia using a chimeric adenovirus, Ad5/F35

PURPOSE

Expression of the FHIT protein is lost or reduced in most solid tumors and a significant fraction of hematopoietic malignancies. Adenovirus 5 (Ad5) virus or adeno-associated viral vectors have been used to study the tumor suppressor function of FHIT in solid tumors, but these tools have not been effective in leukemias. We have generated a chimeric FHIT-containing adenovirus composed of Ad5 and the group B adenovirus called F35 with which we have been able to efficiently infect hematopoietic cells.

EXPERIMENTAL DESIGN

Infection efficiency of Ad5/F35-FHIT and Ad5/F35-GFP viruses was tested in leukemia cell lines that lacked FHIT expression, and biological effects of successful infection were assessed. An acute myelogenous leukemia, a chronic myelogenous leukemia, and four acute lymphoblastic leukemia human cell lines were examined as well as two EBV-transformed B lymphoblastoid cell lines that expressed endogenous FHIT.

RESULTS

Two of four acute lymphoblastic leukemia cell lines, Jurkat and MV4;11, which were efficiently infected with Ad5/F35-FHIT, underwent growth suppression and massive induction of apoptosis without apparent activation of caspase-8 or caspase-2 and late activation of caspase-3. Treatment of infected cells with caspase-9 and caspase-3 inhibitors partially blocked FHIT-induced apoptosis. The two remaining infected acute lymphoblastic leukemia cell lines, Molt-3 and RS4;11, were apparently unaffected. Restoration of FHIT expression in the chronic myelogenous leukemia K562 cell line and the acute myelogenous leukemia KG1a cell line also induced apoptosis but at later time points than seen in the acute lymphoblastic leukemia Jurkat and MV4;11 cell lines. I.v. injection of Ad5/F35-FHIT-infected Jurkat cells resulted in abrogation of tumorigenicity in the NOD/SCID xenogeneic engraftment model.

CONCLUSION

FHIT restoration in some FHIT-deficient leukemia cells induces both antiproliferative and proapoptotic effects involving the intrinsic caspase apoptotic pathway.

Adenovirus type 5 exerts multiple effects on the expression and activity of cytosolic phospholipase A2, cyclooxygenase-2, and prostaglandin synthesis

In this study, we examine how infection of murine and human fibroblasts by adenovirus (Ad) serotype 5 (Ad5) affects the expression and activity of cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2 (COX-2), and production of PGs. Our experiments showed that infection with Ad5 is accompanied by the rapid activation of cPLA2 and the cPLA2-dependent release of [3H]arachidonic acid ([3H]AA). Increased expression of COX-2 was also observed after Ad infection, as was production of PGE2 and PGI2. Later, however, as the infection progressed, release of [3H]AA and production of PGs stopped. Late-stage Ad5-infected cells also did not release [3H]AA or PGs following treatment with a panel of biologically diverse agents. Experiments with UV-inactivated virus confirmed that Ad infection is accompanied by the activation of a host-dependent response that is later inhibited by the virus. Investigations of the mechanism of suppression of the PG pathway by Ad5 did not reveal major effects on the expression or activity of cPLA2 or COX-2. We did note a change in the intracellular position of cPLA2 and found that cPLA2 did not translocate normally in infected cells, raising the possibility that Ad5 interferes with the PG pathway by interfering with the intracellular movement of cPLA2. Taken together, these data reveal dynamic interactions between Ad5 and the lipid mediator pathways of the host and highlight a novel mechanism by which Ad5 evades the host immune response. In addition, our results offer insight into the inflammatory response induced by many Ad vectors lacking early region gene products.

Genotype prevalence and risk factors for severe clinical adenovirus infection, United States 2004-2006

BACKGROUND

Recently, epidemiological and clinical data have revealed important changes with regard to clinical adenovirus infection, including alterations in antigenic presentation, geographical distribution, and virulence of the virus.

METHODS

In an effort to better understand the epidemiology of clinical adenovirus infection in the United States, we adopted a new molecular adenovirus typing technique to study clinical adenovirus isolates collected from 22 medical facilities over a 25-month period during 2004-2006. A hexon gene sequence typing method was used to characterize 2237 clinical adenovirus-positive specimens, comparing their sequences with those of the 51 currently recognized prototype human adenovirus strains. In a blinded comparison, this method performed well and was much faster than the classic serologic typing method.

RESULTS

Among civilians, the most prevalent adenovirus types were types 3 (prevalence, 34.6%), 2 (24.3%), 1 (17.7%), and 5 (5.3%). Among military trainees, the most prevalent types were types 4 (prevalence, 92.8%), 3 (2.6%), and 21 (2.4%).

CONCLUSIONS

For both populations, we observed a statistically significant increasing trend of adenovirus type 21 detection over time. Among adenovirus isolates recovered from specimens from civilians, 50% were associated with hospitalization, 19.6% with a chronic disease condition, 11% with a bone marrow or solid organ transplantation, 7.4% with intensive care unit stay, and 4.2% with a cancer diagnosis. Multivariable risk factor modeling for adenovirus disease severity found that age <7 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4-7.4), chronic disease (OR, 3.6; 95% CI, 2.6-5.1), recent transplantation (OR, 2.7; 95% CI, 1.3-5.2), and adenovirus type 5 (OR, 2.7; 95% CI, 1.5-4.7) or type 21 infection (OR, 7.6; 95% CI, 2.6-22.3) increased the risk of severe disease.

Identifying functional adenovirus-host interactions using tandem mass spectrometry

We describe a systematic, high-throughput approach to identify proteins involved in functional adenovirus (Ad)-host interactions in vitro and in vivo. We were particularly interested in identifying cellular proteins that interact with fiber knob, which is the moiety within the Ad capsid responsible for high-affinity attachment of virus to cellular receptors. We used recombinant fiber knob domains from members of group C and B Ads to purify virus interacting proteins from cell membrane lysates and from human and mouse plasma. Using tandem mass spectrometry, we identified a number of candidate Ad-interacting proteins, including functional cellular receptors and previously unknown interacting partners such as complement component C4-binding protein and other blood proteins that presumably are involved in Ad infection after intravenous virus application. The ability of these proteins to bind to Ad was further confirmed using in vitro protein binding assays as well as infection competition assays. The approach of using a structural protein can be universally applied for a variety of viral and nonviral pathogens and can reveal host cell factors critical in viral infection, immune evasion, and tissue specificity. This information is also a prerequisite to assess in vivo safety and efficacy of Ad-based gene transfer vectors.

Quantification of adenovirus species B and C viremia by real-time PCR in adults and children undergoing stem cell transplantation

Adenovirus infection during stem cell transplantation is associated with high morbidity and mortality. Adenovirus species B and C have been the main causes for these infections; however, epidemiological details about the species are still unclear. To clarify the contributions of species B and C adenovirus, the DNA was tested serially by quantitative real-time PCR in peripheral blood, stool and urine of 32 patients (16 adults and 16 children) undergoing stem cell transplantation. Adenovirus species B viremia was detected in 10 of 16 adult and 6 of 16 pediatric transplant recipients. Adenovirus species C viremia was also detected simultaneously in five adult and three pediatric recipients. The stool and urine of patients with adenovirus viremia were also positive for the same adenovirus species as in blood. In contrast, in none of 50 healthy adult controls was adenovirus species B or C viremia detected. Among patients who developed adenovirus viremia, one adult recipient developed disseminated disease and died from multiple organ failure. The remaining patients experienced fever of several degrees and/or diarrhea during the period of adenovirus viremia; however, they all recovered without antiviral therapy. The results indicated that stem cell transplantation was frequently associated with adenovirus species B or C viremia, although it did not always cause serious infectious complications.

Invasive adenoviral infections in T-cell-depleted allogeneic hematopoietic stem cell transplantation: high mortality in the era of cidofovir

BACKGROUND

Adenovirus (ADV) infection occurs in 5-21% of allogeneic hematopoietic stem cell transplants (HSCT). Symptomatic enteritis and hemorrhagic cystitis may be encountered but are seldom fatal. In contrast, mortality rates of up to 75% are reported for adenoviral pneumonia or hepatitis. Cidofovir is currently being increasingly used for treatment of adenoviral infections after HSCT. The efficacy of cidofovir in patients with invasive adenoviral infection is not established.

FINDINGS

We reviewed 687 adult and pediatric patients who received allogeneic HSCT at our institution from 1998 through June 2005. ADV was isolated from 64 (9.3%) patients. Eleven patients received cidofovir for invasive disease occurring at median 39 days (range 3-145) post HSCT. The median age was 40 (range 6-61) years. Seventy-three percent received a T-cell-depleted graft and 18% had grade 3-4 graft-versus-host disease (GVHD) of the gut. Three out of 3 (100%) patients with adenoviral pneumonia died. One patient with hepatitis, cholecysitis, and viremia cleared the infection after 3 months. Two out of 7 (28.6%) patients with hemorrhagic colitis or cystitis died of ADV (1 with extensive GVHD).

CONCLUSION

Mortality rates of ADV pneumonitis after allogeneic HSCT remain high in the era of cidofovir. Clinical trials are needed to evaluate management strategies for this life-threatening infection.

Adenovirus infection after allogeneic stem cell transplantation

Adenovirus infection after allogeneic hematopoietic stem cell transplantation (HSCT) is an emerging pathogen causing relevant morbidity and mortality, with preponderance in children. During the last years, basic research on the biology of the virus and host immune response ameliorated the diagnostic, surveillance, and therapeutic strategies. Risk factors for infection commonly have an impact on T-cell reconstitution, such as T-cell depleted graft, unrelated or HLA-mismatched donor transplantation, and GvHD. Weekly surveillance by PCR in stool and blood till day 100 or longer post-HSCT and pre-emptive therapy with cidofovir are the mainstay of the current approach to adenoviral infections post-HSCT. Since a sufficient host T-cell response is essential to clear the virus, diagnostic procedures for detection of virus-specific T-cells have recently been developed to assess the risk of the infection. Furthermore, adoptive immunotherapy is a new treatment option for patients with absent specific T-cell response and present systemic adenoviral infection.

[Current techniques used for the diagnosis of respiratory virus infectious in intensive care units]

Plusieurs centaines de virus respiratoires différents peuvent être détectés chez les patients atteints d'une infection virale respiratoire et hospitalisés dans un service de réanimation : virus influenza, virus respiratoire syncytial, virus para-influenza, adénovirus, coronavirus, rhinovirus, entérovirus, métapneumovirus humain, bocavirus… La recherche de ces virus doit être effectuée sur un prélèvement nasal ou trachéobronchique, riche en cellules épithéliales. Chez les patients immunodéprimés, il faut ajouter un lavage bronchoalvéolaire pour rechercher le cytomégalovirus et les adénovirus. La mise en évidence d'antigènes viraux par immunofluorescence (IF) ou technique immunoenzymatique dans les cellules infectées est en théorie la méthode la plus simple et rapide à utiliser. Comme pour toutes les techniques de diagnostic, la qualité du prélèvement est un déterminant majeur de son efficacité. Cette méthode est malheureusement peu sensible dans les infections respiratoires chez l'adulte. La recherche virale en culture, compliquée et de réponse tardive, peut être utile dans ce cas en raison de son efficacité. Les méthodes PCR sont plus efficaces : elles peuvent identifier les virus non détectés par les techniques conventionnelles et elles augmentent l'isolement des virus classiques. Elles permettent aussi d'identifier les sous-types viraux, d'étudier par séquençage la variabilité génétique des souches et de quantifier la charge virale respiratoire. Les techniques multiplex recherchant plusieurs virus directement dans les prélèvements sont les plus adaptées au diagnostic en raison du nombre de virus à rechercher. Des méthodes PCR en temps réel, fournissant un résultat rapide, ont été récemment développées. La richesse en cellules et le transport du prélèvement sont moins critiques pour les recherches virales en PCR que pour les techniques conventionnelles d'IF et de culture. De plus, les acides nucléiques persistent plus longtemps que les virus infectieux, permettant ainsi un diagnostic plus tardif. Néanmoins, dans un laboratoire de virologie clinique où la rapidité, le coût modéré et la simplicité des techniques sont des exigences prioritaires, le meilleur choix est d'utiliser séquentiellement l'IF et les PCR multiplex. Le développement des outils de PCR multiplex en temps réel est la priorité majeure du futur.

Quantitative detection and rapid identification of human adenoviruses

We have established a method of quantitative detection and rapid identification of human adenoviruses (hAdVs). Using LightCycler PCR with a primer set, we were able to amplify 554 bp of the hexon gene from each of 51 prototype strains of hAdVs. The sensitivity of LightCycler PCR was 10 copies of hAdV DNA/reaction. When LightCycler PCR was performed using a set of primers, hAdV was positive for 74.4% (99 of 133) of conjunctivitis patients and for 27.3% (81 of 297) of respiratory infection patients. We also attempted to measure hAdV in the potentially contaminated eye drops used by patients, detecting 5.4 x 10(2) to 1.6 x 10(6) copies/ml of hAdV. We determined the 350-bp nucleotide sequence of the amplified hexon gene and compared it with the sequences of the 51 prototype strains. Phylogenetic analysis based on 350 bp of the hexon gene identified 99 positive conjunctival swabs as 24 cases of AdV type 3 (AdV-3), 14 cases of AdV-4, 1 case of AdV-8, 19 cases of AdV-19a, and 41 cases of AdV-37. The 81 sequences from pharyngeal or nasal mucus swabs were identified as 29 cases of AdV-2, 18 cases of AdV-1, 18 cases of AdV-5, 12 cases of AdV-4, 2 cases of AdV-37, 1 case of AdV-3, and 1 case of AdV-6. LightCycler PCR followed by phylogenetic analysis provides an effective tool for the rapid identification of hAdVs and for studying molecular epidemiology.

Adenovirus-specific CD4+ T cell clones recognizing endogenous antigen inhibit viral replication in vitro through cognate interaction

Human adenovirus (HAdV) infection is a frequent and potentially severe complication following allogeneic stem cell transplantation in children. Because treatment with antiviral drugs is often ineffective, adoptive transfer of donor-derived HAdV-specific T cells able to control viral replication of HAdV of multiple serotypes may be an option for therapy. In healthy donors, predominantly HAdV-specific T cells expressing CD4 are detected. In this study, a preclinical in vitro model was used to measure the antiviral effect of HAdV-specific CD4+ T cells. CD4+ HAdV-specific T cell clones restricted by HLA class II molecules were generated and most of these clones recognized conserved peptides derived from the hexon protein. These cross-reactive T cell clones were able to control viral replication of multiple serotypes of HAdV in EBV-transformed B cells (B-LCL), melanoma cells (MJS) and primary bronchial epithelial cells through cognate interaction. The HAdV-specific CD4+ T cell clones were able to specifically lyse infected target cells using a perforin-dependent mechanism. Antigenic peptides were also presented to the CD4+ T cell clones when derived from endogenously produced hexon protein. Together, these results show that cross-reactive HAdV-specific CD4+ T cells can control replication of HAdV in vitro and provide a rationale for the use of HAdV-specific T cells in adoptive immunotherapy protocols for control of life-threatening HAdV-infections in immunocompromised patients.

Structural and biochemical characterization of a human adenovirus 2/12 penton base chimera

The vertex of the adenoviral capsid is formed by the penton, a complex of two proteins, the pentameric penton base and the trimeric fiber protein. The penton contains all necessary components for viral attachment and entry into the host cell. After initial attachment via the head domain of the fiber protein, the penton base interacts with cellular integrins through an Arg-Gly-Asp (RGD) motif located in a hypervariable surface loop, triggering virus internalization. In order to investigate the structural and functional role of this region, we replaced the hypervariable loop of serotype 2 with the corresponding, but much shorter, loop of serotype 12 and compared it to the wild type. Here, we report the 3.6 A crystal structure of a human adenovirus 2/12 penton base chimera crystallized as a dodecamer. The structure is generally similar to human adenovirus 2 penton base, with the main differences localized to the fiber protein-binding site. Fluorescence anisotropy assays using a trimeric fiber protein mimetic called the minifiber and wild-type human adenovirus 2 and chimeric penton base demonstrate that fiber protein binding is independent of the hypervariable loop, with a K(d) for fiber binding estimated in the 1-2 microm range. Interestingly, competition assays using labeled and unlabeled minifiber demonstrated virtually irreversible binding to the penton base, which we ascribe to a conformational change, on the basis of comparisons of all available penton base structures.

Typing of human adenoviruses in specimens from immunosuppressed patients by PCR-fragment length analysis and real-time quantitative PCR

Currently, 51 human adenovirus (AdV) serotypes, which are divided into six species (A to F), are known. AdV infections are a major cause of morbidity and mortality in immunosuppressed individuals, particularly in allogeneic stem cell transplant (SCT) recipients. Any AdV species may cause life-threatening disease, but little information is available on the clinical relevance of individual serotypes. The use of serological testing for serotype identification is limited due to the impaired immune response during the posttransplant period. A new molecular approach to serotype identification is presented here that exploits variable regions within the hexon gene. All serotypes belonging to the species A, B, C, E, and F can be determined by fragment length analysis of a single PCR product. For species C, which is the most prevalent in many geographic regions, an alternative technique based on serotype-specific real-time quantitative PCR was established. Of 135 consecutive pediatric patients screened for AdV infections after allogeneic SCT, 40 tested positive. Detailed analysis revealed the presence of 10 different serotypes; serotypes 1 and 2 from species C (C01 and C02) showed the highest prevalence, accounting for 77% of the AdV-positive cases. Representatives of other species were observed less commonly: serotype A12 in 6.5%; serotype A31 in 4.5%; and B03, B16, C05, C06, D19, and F41 in 2%. The approach to rapid molecular serotype analysis presented here provides a basis for detailed studies on adenovirus epidemiology and on the transmission of nosocomial infections. Moreover, in view of the increasing importance of tailored therapy approaches, serotype identification may in the future have implications for the selection of the most appropriate antiviral treatment.

Human CD4+ T cells stimulated by conserved adenovirus 5 hexon peptides recognize cells infected with different species of human adenovirus

The immune response against human adenovirus (HAdV) has gained interest because of the application of HAdV-based vectors in gene therapy and the high incidence of infections in pediatric recipients of allogeneic stem cell grafts. Because antiviral medication is frequently ineffective, the option of adoptive transfer of HAdV-specific donor-derived T cells in these immunocompromised patients is investigated. To generate good manufacturing practice-compatible reagents, a panel of 63 long, overlapping, peptides of the hexon protein was screened for recognition by T cells. Five conserved peptides of 30 amino acids were identified that were recognized by the majority of adult donors. CD4+ T cells from long-term cultures of PBMC, stimulated with this set of five peptides, recognized cells infected with HAdV serotypes belonging to different species. These data demonstrate that adult human T cells preferentially recognize conserved sequences of amino acid residues from a structural protein of HAdV. In the context of gene therapy, this observation may limit the beneficial effect of switching to HAdV-based vectors derived from less common serotypes of HAdV in an attempt to circumvent pre-existing immunity. However, this cross-reactivity benefits the application of HAdV-specific T cells for adoptive immunotherapy in immunocompromised transplant recipients.