Increasing incidence of adenovirus disease in bone marrow transplant recipients

Invasive adenoviral infection in a recipient of unrelated bone marrow transplantation: Problems with diagnostic PCR

A hematopoietic stem cell transplantation (SCT) recipient developed severe diarrhea and fever. A rapid test for the presence of adenovirus (AdV)-specific antigen in the patient's stools was positive; however, AdV genome was not detected by conventional or real-time polymerase chain reaction (PCR). AdV was confirmed by specific PCR for AdV serotype 7 and by an AdV hexon/fiber gene DNA sequence homology search of the PCR product. We suspect that conventional/real-time PCR failed to detect AdV due to nine silent single base substitutions in the extracted AdV genome. Treatment with 1 mg/kg cidofovir (CDV) intravenously three times a week was effective.

Detection of adenovirus-specific T cells in children with adenovirus infection after allogeneic stem cell transplantation

Human adenovirus (ADV) infection is an important complication post allogeneic stem cell transplantation (SCT), especially in children, with significant morbidity and mortality despite new antiviral treatment strategies. Although the control of infection seems to require T cells, characterization of ADV-specific T cells post-SCT has not been reported to date. Therefore, we prospectively studied the occurrence of ADV-specific T cells in children with (n = 21) and without (n = 25) ADV-infection postallogeneic SCT and in healthy donors (n = 53). ADV-associated mortality occurred in seven of 21 children. After stimulation ex vivo with ADV-lysate, interferon-gamma-secreting T cells were analysed by flow cytometry. All the patients with ADV-associated mortality had no specific T cells, although reconstitution of absolute lymphocyte counts exceeded 0.3 x 10(9)/l within 30 d post-transplant. Patients who cleared ADV infection had significantly higher frequencies (mean +/- standard deviation, 0.56 +/- 0.5%) of ADV-specific T cells until day 200 post-SCT, than patients without ADV-infection (0.12 +/- 0.1%). These data suggest that ADV-specific T-cell reconstitution is protective against life-threatening ADV-infections postallogeneic SCT.

Frequent detection of respiratory viruses in adult recipients of stem cell transplants with the use of real-time polymerase chain reaction, compared with viral culture

Background. Respiratory virus infections have been recognized as important causes of severe pneumonia in patients who have undergone stem cell transplantation (SCT). Reported incidences of respiratory virus infection in adult SCT recipients vary in the literature from 3.5% to 36% when determined by viral culture. However, a more sensitive method to assess the presence of respiratory viruses in the lower airways may be important for delineation of the true incidence of respiratory virus—associated pneumonia and may be essential for guidance on implementation of antiviral therapy and prevention or limitation of nosocomial spread of infection with respiratory viruses.

Methods. To determine the incidence and severity of respiratory tract illness (RTI) and to assess the diagnostic value of real-time reverse-transcriptase polymerase chain reaction (RT-PCR) versus viral culture, 72 SCT recipients were monitored during a 6-month period.

Results. A respiratory virus was detected in 21% of episodes of RTI by viral culture and in 63% of RTI episodes by real-time RT-PCR (P < .0001). In lower respiratory tract illness, real-time RT-PCR was much more sensitive than viral culture for detection of respiratory virus (73% vs. 9%; P = .008). The mortality rate for patients with respiratory virus—associated lower respiratory tract illness (25%) was similar to rates reported elsewhere. Respiratory viruses (predominantly rhinovirus) were detected by real-time RT-PCR in 9% of samples obtained from symptom-free SCT recipients at predetermined times by real-time RT-PCR and by viral culture in 1% (P < .0001), indicating that asymptomatic shedding of respiratory viruses also occurs.

Conclusion. We conclude that, although asymptomatic shedding of respiratory virus occurs, respiratory viruses are frequent causes of RTI in SCT recipients.

Fatal adenovirus hepatitis during standard chemotherapy for childhood acute lymphoblastic leukemia

Fulminant hepatitis is a rare complication of adenoviral infection that has not previously been reported in children receiving standard chemotherapy for acute leukemia. The authors have observed fatal adenovirus hepatitis in three children receiving first-line chemotherapy for acute lymphoblastic leukemia (ALL). The patients presented 10, 17, and 8 months into therapy according to the UKALL XI (third intensification), UKALL 97/99 (maintenance), and pilot UKALL 2003 (delayed intensification II) protocols, respectively. All patients received aggressive supportive care and intravenous immunoglobulins. The second and third patients were also treated with intravenous cidofovir. Despite these measures, all three children deteriorated rapidly and died of fulminant liver failure. Although rare, adenovirus infection should be considered in the differential diagnosis of acute hepatitis in children receiving standard chemotherapy for ALL.

Adenovirus as an emerging pathogen in immunocompromised patients

Adenoviruses are non-enveloped, lytic, DNA viruses capable of infecting most animal species. There are 51 different human adenovirus serotypes, which are grouped from A to F on the basis of genome size, composition, homology and organization. Pathogenicity varies according to group and type, but infections are generally well controlled by the host immune system in immunocompetent individuals. However, in the immunosuppressed, adenoviral infections are a frequent cause of morbidity and mortality. To date there is no effective therapy. Adoptive transfer of immune T cells offers a therapeutic option, but this strategy has been hindered by the lack of information on targets of protective cellular immunity, and by the immunological heterogeneity of the 51 human adenoviruses. Nevertheless, until such an approach is implemented, or an effective antiviral agent becomes commercially available, it is likely that adenovirus infections will continue to be responsible for a significant number of virus-associated deaths each year.

Adenovirus infections in stem cell transplant recipients: recent developments in understanding of pathogenesis, diagnosis and management

Adenovirus is increasingly recognized as an important pathogen in stem cell transplant recipients, reflecting increased awareness about the virus, together with changes in transplant practice such as the performance of more high-risk transplants, and improvements in diagnostic methods. In retrospective studies, the reported incidence of adenovirus infections ranged between 4-20% with a similar variation in the proportion of patients developing invasive disease. In contrast, the incidence of adenovirus infection varies between 20-30% in recent prospective studies on T-cell depleted or mismatched allografts and about 30-40% of these patients develop invasive disease. These prospective studies have established a relationship between the risk of invasive adenovirus disease and a number of factors such as the extent of T-cell depletion, the intensity of immunosuppressive therapy and the kinetics of lymphocyte recovery post-transplant. Polymerase chain reaction (PCR) assays to detect adenovirus DNA in peripheral blood have shown a strong correlation between viremia and the risk of disseminated adenovirus disease. These developments have led to the possibility of a preemptive antiviral treatment strategy for asymptomatic adenovirus infections. In addition, a better understanding of the interactions between adenovirus and host immune system in the post-transplant setting might enable development of effective immunotherapeutic strategies against adenovirus infections.

Incidence and outcome of adenovirus disease in transplant recipients after reduced-intensity conditioning with alemtuzumab

Adenoviruses are emerging as a major cause of infectious complications after allogeneic transplantation. We evaluated the incidence and outcome of symptomatic adenovirus infection or adenovirus disease after alemtuzumab-based reduced-intensity conditioning in 86 consecutive patients. The overall probability of adenovirus disease was 18.4% (11/86 patients). Five patients died of progressive adenovirus disease, and this was the most important infectious cause of mortality in this cohort. The probability of nonrelapse mortality was 49% in patients with adenovirus disease compared with 25.5% in those without (P=.007). The severity of lymphocytopenia and continuation of immunosuppressive therapy were the most important risk factors for progressive adenovirus disease and death. In contrast, patients who were not receiving immunosuppressive therapy or had had it reduced or withdrawn cleared the virus. We also detected a correlation between the lack of preemptive anti-cytomegalovirus (CMV) therapy for CMV reactivation and the risk of progressive adenovirus disease (P=.05). Our findings highlight the emergence of adenovirus as an important posttransplantation pathogen even after reduced-intensity conditioning and demonstrate the effect of the severity of lymphocytopenia, anti-CMV prophylaxis, and immunosuppressive therapy on the outcome of adenovirus disease.

Cidofovir for treating adenoviral hemorrhagic cystitis in hematopoietic stem cell transplant recipients

Adenovirus (AdV) infection is an important cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. We treated 16 patients with AdV hemorrhagic cystitis (HC) following HSCT with cidofovir (CDV; 1 mg/kg/day, three times weekly for 3 weeks). Patients included 10 males and six females with a median age of 50 years (range 10-62). Two of the 16 patients were unevaluable because of early death from nonadenoviral causes. CDV therapy cleared AdV from urine in 12 of 14 patients (86%). Of 14 patients, 10 (71%) showed clinical improvements in HC. Among 14 patients, seven (50%) had avoided renal damage, the most important CDV toxicity. One patient previously treated with foscarnet for cytomegalovirus (CMV) required hemodialysis, and CDV treatment was discontinued. In another patient, CDV treatment was discontinued because of grade 2 nephrotoxicity. Four patients became positive for CMV antigenemia while being treated with CDV, and two developed herpes simplex virus (HSV) stomatitis while being treated with CDV. CDV proved effective in treating AdV HC in transplant patients. However, CDV at 1 mg/kg/day given three times weekly failed to prevent breakthrough infection with CMV and HSV in some patients.

Adenoviral infection in hematopoietic stem cell transplantation: early diagnosis with quantitative detection of the viral genome in serum and urine

Early diagnosis and prompt introduction of effective therapy are imperative to manage systemic, often fatal adenoviral (AdV) disease following hematopoietic stem cell transplantation (SCT). We evaluated the usefulness of real-time polymerase chain reaction (PCR) in the diagnosis of AdV disease in SCT recipients. Seven SCT recipients, including three with AdV disease, were retrospectively evaluated for AdV genome detection. In serum specimens, the AdV genome was detected at >10(3) copies/ml in the pre-SCT period in two of the five recipients studied. These two patients subsequently developed AdV disease. The three patients with AdV disease had high levels of >10(5) copies/ml during the 4-6 weeks post-SCT period. In none of these patients was the AdV genome detected in urine specimens in pre-SCT period. However, three recipients with detectable urinary levels during the period 1-2 weeks post-SCT subsequently developed AdV disease. Regarding the outcome, two of the three patients with AdV disease died of progressive renal failure. Our results suggest that quantitative determination of the AdV genome in serum and urine is useful to identify patients at high risk of developing AdV disease. Prospectively applied, these measures are expected to improve the dismal outcome of AdV disease in SCT recipients.

Adenovirus hexon T-cell epitope is recognized by most adults and is restricted by HLA DP4, the most common class II allele

The immunogenicity of adenovirus (Ad) vectors is enhanced by virus-specific memory immune responses present in most individuals as a result of past exposure to these ubiquitous pathogens. We previously identified the first human T-cell epitope from the major capsid protein hexon, H910-924, and found that it is highly conserved among different Ad serotypes. Memory/effector T-cell responses to H910-924 were detected in 14 of 18 (78%) healthy adults by an interferon-gamma ELISPOT assay. Hexon peptide-specific CD4 T-cell lines were generated from three HLA-typed donors and analyzed using a panel of HLA homozygous B-cell lines and monoclonal antibodies to HLA class II loci. These studies reveal that the hexon epitope is restricted by HLA DP4, a class II allele present in 75% of the population. Analysis of overlapping peptides and peptides with single residue mutations identified a HLA DP4-binding motif. Additionally, antibodies to the hexon peptide were detected in all donor sera by dot blot assay and ELISA. Therefore, most individuals exhibit both memory B- and T-cell responses to this highly conserved epitope on hexon, an obligate component of all Ad vectors, including 'gutted' vectors. These data suggest that current strategies for the use of Ad gene therapy vectors will not evade memory immune responses to Ad.

Treatment of adenovirus infections in the immunocompromised host

Adenovirus infections are increasing as causes of morbidity and mortality in severely immunocompromised patients. The currently available antiviral agents, ribavirin and cidofovir, have yielded mixed results in case reports and small case series. Similar to cytomegalovirus disease, established adenovirus disease is often difficult to treat. Therapy may yield poor results, even when effective antiviral drugs are used. New strategies, including pre-emptive therapy, should be tested in prospective, clinical trials. New agents and adoptive transfer of specific T-cells to adenovirus might improve the current situation.

Fatal disseminated mouse adenovirus type 1 infection in mice lacking B cells or Bruton's tyrosine kinase

Mouse adenovirus type 1 (MAV-1) infection of B-cell-deficient and Bruton's tyrosine kinase (Btk)-deficient mice resulted in fatal disseminated disease resembling human adenovirus infections in immunocompromised patients. Mice lacking B cells or Btk were highly susceptible to acute MAV-1 infection, in contrast to controls and mice lacking T cells. To our knowledge, this is the first demonstration that mice with an X-linked immunodeficiency phenotype (Btk deficient) are susceptible to virus-induced disease. Mice lacking B cells or Btk on a C57BL/6 background succumbed with encephalomyelitis, hepatitis, and lymphoid necrosis. Mice lacking B cells on a BALB/c background succumbed with enteritis and hepatitis. Survival of acute MAV-1 infection correlated with early T-cell-independent neutralizing antibody and T-cell-independent antiviral immunoglobulin M. Treatment of MAV-1-infected Btk(-/-) mice 4 to 9 days postinfection with antiserum harvested 6 to 9 days postinfection from MAV-1-infected Btk(+/+) mice was therapeutic. Our findings implicate a critical role for B-cell function in preventing disseminated MAV-1 infection, particularly production of early T-cell-independent antiviral immunoglobulin M.

ADENOVIRUS NEPHRITIS IN HEMATOPOIETIC STEM-CELL TRANSPLANTATION

BACKGROUND

Although adenovirus (ADV) infections may involve many different organs, kidney infection is seldom reported in association with hematopoietic stem-cell transplantation (HSCT).

METHODS

In the present study, the diagnosis of ADV nephritis was established by the culture isolation of adenovirus or the immunocytochemical (ICC) demonstration of the adenoviral hexon protein. The clinical description of ADV nephritis was derived from retrospective review of clinical records to identify signs, symptoms, outcomes, and associated complications. ADV nephritis was characterized as a pathologic entity by the histologic and ICC analysis of tissue from the kidney and all other major organs to establish the distribution of the virus and the associated gross and microscopic alterations.

RESULTS

ADV nephritis was diagnosed in 21 HSCT patients, in 2 by biopsy and in 19 at autopsy. Focal signs of BK nephropathy were present in only one patient. Twenty had received allogeneic marrow and one had undergone autologous transplantation. Graft-versus-host disease was a risk factor. ADV nephritis was associated with acute renal failure in 90% of the infected patients. Prodromal symptoms included fever, hematuria, and flank pain. Adenoviruria was present in 78% of the patients. Kidney infection as determined by viral antigen ICC predominantly involved the tubular epithelial cells. ADV organ tropism was striking, with sero-types from subgenus B, cluster 2, primarily responsible for cases involving predominantly the urinary system. ADV infection was a major cause of death in 17 patients.

CONCLUSIONS

ADV nephritis is a specific renal complication in HSCT patients that can be diagnosed by renal biopsy in patients with hematuria and adenoviruria.

Isolation and expansion of human adenovirus–specific CD4+ and CD8+ T cells according to IFN-γ secretion for adjuvant immunotherapy

OBJECTIVE

In patients with lymphopenia following allogeneic stem cell transplantation adenovirus (ADV) infection is associated with high morbidity and mortality despite aggressive antiviral drug therapy. Virus-specific T cells seem to be essential for virus elimination. The aim of this study was to isolate and expand donor-derived human ADV-specific T lymphocytes for adoptive transfer of sufficient cell numbers to restore protective immunity after allogeneic stem cell transplantation.

MATERIALS AND METHODS

A clinical-grade strategy to generate ADV-specific T cells using the interferon-gamma (IFN-gamma) secretion assay, followed by expansion to numbers sufficient for clinical application with interleukin-2 (IL-2) and feeder cell stimulation, is described.

RESULTS

A mean number of 3.4 x 10(6) (+/-3 SD) ADV antigen-specific T lymphocytes were isolated from 0.1 to 2 x 10(9) mononuclear cells from peripheral blood (n=5) or leukapheresis products (n=6). Characterization of ADV-specific T cells after isolation revealed a mean purity of 85.1% (+/-12% SD) using antigen-specific intracellular cytokine staining. Isolated cells were expanded ex vivo for a median of 18 days (range 7-29 days; n=5) to greater than 10(8) total cells using IL-2 and autologous feeder cell stimulation. ADV-specific response to adenovirus antigen was confirmed in the generated T cell lines, using intracellular cytokine staining, IFN-gamma Elispot assay, and (3)H-thymidine uptake. Generated T-cell lines showed specific killing of ADV-infected B-LCL (n=4). Alloreactive proliferation of generated T-cell lines in mixed lymphocyte cultures was significantly reduced when compared to unmanipulated PBMCs.

CONCLUSION

Generation of adenovirus-specific T cells in a simple and rapid clinical-grade protocol was established, using IFN-gamma secretion assay with short expansion times, leading to sufficient numbers of ADV-specific T cells that can be used for adoptive immunotherapy.

Multiplexed, real-time PCR for quantitative detection of human adenovirus

Adenovirus infection is becoming increasingly recognized as a cause of morbidity and mortality in the immunosuppressed patient population. While early detection and quantitation of adenovirus in peripheral blood has been suggested as a means of directing and monitoring antiviral therapy in these patients, few methods have been published, particularly with respect to viral quantitation. A multiplexed real-time PCR assay was developed that can quantitatively detect a wide range of known serotypes of human adenovirus, including all of subgroups A to C. This assay was compared to a qualitative, Southern blot-based PCR assay by using 45 peripheral blood specimens from 16 patients. There was 100% concordance between the two tests in terms of qualitative results. The real-time assay detected adenovirus in patient samples at levels from <200 to 266,681 copies/ml of blood. By using control viral samples, sensitivity was demonstrated to less than 10 copies of viral genome per reaction and quantitative linearity was demonstrated from 10 to 10(6) copies of input viral DNA. Equivalent sensitivity and linearity were demonstrated for 15 different reference serotypes of adenovirus. Eleven other viral serotypes have complete target region sequence homology to one or more of the strains tested. No cross-reactivity was noted with other commonly isolated viral species. Sequence analysis showed no significant homology with any other human pathogens (bacterial or viral). This assay allows rapid, sensitive, and specific quantitation of adenovirus and may have a significant impact on the care of immunocompromised patients at risk for disseminated viral infection.

Mechanisms of E3 Modulation of Immune and Inflammatory Responses

Adenoviruses contain genes that have evolved to control the host immune and inflammatory responses; however, it is not clear whether these genes function primarily to facilitate survival of the virus during acute infection or during its persistent phase. These issues have assumed greater importance as the use of adenoviruses as vectors for gene therapy has been expanded. This review will focus on the mechanism of immune evasion mediated by the proteins encoded within the early region 3 (E3) transcription region, which affect the functions of a number of cell surface receptors including Fas, intracellular cell signaling events involving NF-kappaB, and the secretion of pro-inflammatory molecules such as chemokines. The successful use of E3 genes in facilitating allogeneic transplantation and in preventing autoimmune diabetes in several transgenic mouse models will also be described.

Real-time blood plasma polymerase chain reaction for management of disseminated adenovirus infection

We evaluated the usefulness of quantifying blood plasma adenovirus DNA loads for the management of adenovirus infection. Quantification of adenovirus A, B, and C DNA loads was done with real-time polymerase chain reaction (PCR) assays. Blood plasma specimens obtained from 44 immunocompromised patients were screened prospectively with this method. PCR findings for 36 patients were negative, and none of the patients developed disseminated adenoviral disease. PCR findings for 8 patients were positive; all 8 had invasive adenoviral disease and were treated with cidofovir. Sequential measurements of adenovirus DNA loads were performed to monitor the effect of cidofovir therapy. Decrease in the blood plasma DNA load was significantly higher in patients with a good response to cidofovir than in patients with a poor response and was therefore correlated with survival. Detection of adenovirus DNA in blood plasma appears to be useful for identifying patients at risk for invasive disease. Moreover, quantification of adenovirus DNA loads in plasma is helpful for monitoring the efficacy of antiviral therapy.

Adenovirus enterocolitis in pediatric patients following bone marrow transplantation: report of 2 cases and review of the literature

We report 2 cases of adenovirus enterocolitis in pediatric patients who underwent bone marrow transplantation. The first case involved a 17-year-old adolescent boy with combined immunodeficiency and non-Hodgkin lymphoma who developed chronic graft versus host disease and persistent adenovirus duodenitis. Case 2 involved a 3-year-old boy who received a mismatched unrelated bone marrow transplant for metachromatic leukodystrophy; the boy developed severe graft versus host disease and died of multiorgan failure. At autopsy, diffuse hemorrhagic enterocolitis with changes of severe graft versus host disease and extensive mucosal invasion by adenovirus was found. Awareness and early recognition of this uncommon complication of concomitant graft versus host disease and adenovirus infection could impact therapy and outcome of patients with bone marrow transplant.

Human adenovirus type 35: nucleotide sequence and vector development

In this report, we describe the complete 34,794 base pair genomic sequence of the human adenovirus serotype 35 (Ad35) Holden strain. The viral genome exhibits a compact organization similar to other adenoviral serotypes, with overlapping genes on both strands. In all, 47 open reading frames (ORFs) were identified, including early (E1, 2, 3, 4) and late (L1, 2, 3, 4, 5) regions conserved among the adenoviridae family. In addition, 14 ORFs were identified that do not encode known adenoviral genes. Comparison of the predicted translational products of the conserved genes with those of other adenoviruses revealed that Ad35 has high homology to Ad7, Ad3, Ad21, Ad17, and simian Ads25. Based on the complete Ad35 DNA sequence, E3-, E1-, and E1/E3-deleted Ad35-based vector systems were developed. An HEK293-derived cell line was established for the propagation of the E1-deleted Ad35 vector, avoiding the emergence of replication-competent adenovirus. Moreover, production of the E1-deleted recombinant Ad35 vector was achieved by transient transduction of a plasmid encoding the Ad35 E1B gene in HEK293 cells. Testing showed that the Ad35-based vector efficiently infects both human and rhesus macaque dendritic cells. Our novel Ad35-based vectors and their corresponding packaging cell lines will provide a versatile and powerful system for DNA-based vaccine development and gene therapy applications.

Fiber-modified adenoviruses generate subgroup cross-reactive, adenovirus-specific cytotoxic T lymphocytes for therapeutic applications

Adenovirus (Ad) infections are responsible for considerable morbidity and mortality, particularly in pediatric hematopoietic stem cell transplant (HSCT) recipients. To date there is no therapy. The present study was motivated by the potential for using adoptive immunotherapy as either prophylaxis or treatment for Ad infections and associated diseases. The authors have developed a protocol to reactivate Ad-specific memory T cells from peripheral blood mononuclear cells (PBMCs) using a clinical-grade adenoviral vector. Such lines contain a specific CD4 and CD8 T-cell component and are capable of recognizing and lysing target cells infected with wild-type Ad serotypes from different Ad groups. Furthermore, the frequency of Ad-specific precursors can be determined in PBMCs ex vivo and used as a means to assess changes in Ad-specific T-cell memory responses after infusion. This is the first report of a simple and reproducible method to activate and expand Ad-specific cytotoxic T lymphocytes (CTLs), which should be protective against the range of different Ad subtypes that affect transplant recipients.

Infectious complications after allogeneic stem cell transplantation: epidemiology and interventional therapy strategies--guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

The risk of infection after allogeneic stem cell transplantation is determined by the underlying disease, the intensity of previous treatments and complications that may have occurred during that time, but above all, the risk of infection is determined by the selected transplantation modality (e.g. HLA-match between the stem cell donor and recipient, T cell depletion of the graft, and others). In comparison with patients treated with high-dose chemotherapy and autologous stem cell transplantation, patients undergoing allogeneic stem cell transplantation are at a much higher risk of infection even after hematopoietic reconstitution, due to the delayed recovery of T and B cell functions. The rate at which immune function recovers after hematopoietic reconstitution greatly influences the incidence and type of post-transplant infectious complications. Infection-associated mortality, for example, is significantly higher following engraftment than during the short neutropenic period that immediately follows transplantation.

Comparison of HSV-1 thymidine kinase-dependent and -independent inhibition of replication-competent adenoviral vectors by a panel of drugs

Replication-competent adenoviral vectors hold the promise to be more efficient gene delivery vehicles than their replication-deficient counterparts, but they are also associated with a higher risk for adverse effects, especially in light of the fact that there is no established effective therapy for serious, disseminated adenovirus infection. To assess whether the therapeutic options to inhibit adenoviral replication can be enhanced by expressing a suicide gene, we examined the antiadenoviral effects of 15 drugs against wild-type adenovirus type 5 (Ad5) and an Ad5-based replication-competent vector expressing herpes simplex virus-1 thymidine kinase (HSV-tk) (Ad.OW34) using a real-time polymerase chain reaction -based assay and flow cytometry. Ad5 and Ad.OW34 were highly susceptible to the fluorinated pyrimidine analogs 5-fluoro-2'-deoxyuridine (FUdR), 5-fluorouridine (FUR), and trifluorothymidine (TFT), with a mean 50% inhibitory concentration (IC(50)) ranging from 0.12 to 0.32 microM. The mean IC(50) of ribavirin and cidofovir (CDV) for Ad5, the most frequently used drugs to treat adenovirus disease, was 6.87 and 3.19 microM, respectively. In contrast to Ad5, the Ad.OW34 vector was susceptible to (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdU, IC(50) 0.09 microM), ganciclovir (GCV, IC(50) 0.19 microM), and acyclovir (ACV, IC(50) 32.04 microM). Additionally, we demonstrated in an animal model that Ad.OW34 vector replication can be inhibited significantly by GCV, CDV, and TFT by 35.2, 7.7, and 3.7-fold, respectively, compared to untreated animals. The observed antiadenoviral effects were primarily not through cell killing, since the in vitro 50% cytotoxic concentrations (CC(50)) were more than 1000 times higher than the antiadenoviral IC(50) of the drugs examined, even in cells stably expressing HSV-tk. Since for HSV-tk-dependent inhibition of adenoviral vectors, stability of HSV-tk expression is crucial, we examined Ad.OW34 vector stability, by passaging the vector 10 times serially in the presence of 10 microM GCV. The HSV-tk/GCV system neither changed the susceptibility of Ad.OW34 to GCV significantly nor detectable vector rearrangements occurred, suggesting that the system might be suitable as a fail-safe mechanism to stop adenoviral vector replication.

Respiratory virus infections in the immunocompromised host

The number of immunocompromised children in the population is increasing for a variety of reasons. Common respiratory viruses acquired in the community or in the hospital setting include the ortho- and paramyxoviruses and may cause severe lower respiratory tract disease in these children. Measles is again becoming a threat. Particularly in transplant patients, Herpes group viruses and adenoviruses, often part of a reactivation illness, can cause potentially life-threatening disease. The use of rapid molecular diagnostic techniques and an increasing array of antiviral therapies can help ensure a good outcome in many cases, although controlled clinical trial data are often lacking. Immunotherapeutic strategies using specific antibodies or cytotoxic T cells are being developed and are likely to have an increasing role in prophylaxis and pre-emptive therapy in the future. The development and introduction of vaccines against common respiratory diseases will help reduce the risks faced by these susceptible children.

Molecular monitoring of adenovirus in peripheral blood after allogeneic bone marrow transplantation permits early diagnosis of disseminated disease

Adenovirus (AdV) infection in the course of allogeneic stem cell transplantation (SCT) is associated with high transplant-related morbidity and mortality. Disseminated AdV disease is lethal in most instances. Early detection of AdV infection and identification of patients carrying a high risk of disseminated disease therefore remain a major challenge. In view of the large number of existing AdV types, we have established real-time polymerase chain reaction (PCR) assays permitting sensitive detection and quantification of all 51 currently known human AdV serotypes. In a series of 132 consecutive pediatric patients undergoing SCT, more than 5000 samples derived from peripheral blood (PB), stool, urine, and throat were screened for adenovirus infection by PCR during the posttransplantation period. Thirty-six patients (27%) tested positive by PCR, revealing AdV types of the subgenera A, B, C, D, and F. Except for enteritis in some patients with AdV positivity in stool, detection of the virus at sites other than PB was not associated with clinical signs of virus disease, and transplant-related mortality was not significantly different from AdV-negative patients. By contrast, 82% of patients who had detectable AdV in PB died from infectious complications (P <.001). Monitoring of PB specimens by real-time PCR permitted early diagnosis of invasive AdV infection in all instances. In patients who developed disseminated AdV disease, detection of the virus in PB preceded onset of clinical symptoms by a median of more than 3 weeks. The observation of AdV in peripheral blood may therefore serve as a basis for early initiation of preemptive antiviral treatment.

Adenovirus infection in hematopoietic stem cell transplantation: effect of ganciclovir and impact on survival

Adenoviruses (ADV) are emerging as important causes of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). In mainly non-T-cell depleted HSCT recipients, we analyzed the incidence of ADV infection, risk factors for infection, the effect of ganciclovir administered for prevention of cytomegalovirus (CMV), and the impact of ADV infection on survival. The overall incidence of ADV, irrespective of the method of detection, was 8.5% (450/5233) and 12.3% (43/348) after the first or second allogeneic HSCT, and 6.3% (78/1219) and 6.5% (5/77) after the first or second autologous HSCT, respectively. The most frequent sites of infection and disease were stool and gastrointestinal tract, respectively. Statistically significant risk factors associated with ADV infections among allogeneic recipients included younger age, grade II to IV graft-versus-host disease, year of transplantation, and a second allogeneic HSCT. Furthermore, allogeneic patients seronegative for CMV at transplantation and seropositive allogeneic patients who did not receive ganciclovir, either at engraftment or as pre-emptive therapy on CMV reactivation, were at higher risk of developing ADV infections compared with seropositive patients who received ganciclovir (odds ratio=1.8, 95% confidence interval (CI) 1.2 to 2.8, P=.005 and odds ratio=3.4, 95% CI 2.1 to 5.55, P<.0001, respectively). The hazard of overall mortality was higher in patients who contracted ADV compared with those who did not (hazard ratio 1.5, 95% CI 1.3 to 1.7, P<.0001). This study shows that ADV infections are associated with poor transplantation outcome in T-cell repleted HSCT recipients. Ganciclovir, given for CMV prevention, may have a protective effect. Controlled treatment and prevention studies are warranted.

Adenovirus meningoencephalitis in a patient with large B-cell lymphoma

We report a case of a 58-year-old female with neuromeningeal relapse of a large B-cell lymphoma which developed a meningoencephalitis due to adenovirus (ADV). Diagnosis of suspected viral meningoencephalitis was based on computed tomography (CT) scan radiological pictures, which were atypical for CNS neoplastic infiltrations, and it was confirmed by direct immunofluorescence performed on cerebrospinal fluid. Cultural exams identified adenovirus type 7. The ADV infection resolved after treatment with total four doses of cidofovir. Unfortunately, the hematological disease progressed and the patient died 2 months later from disseminated lymphoma.

The impact of adenovirus infection on the immunocompromised host

Adenovirus (Ad) infections in immunocompromised hosts have increased in frequency as the number of patients with transplants of bone marrow, liver, kidney, heart and other organs increase in number and survive longer. The numbers of such patients have also increased because of the emergence of the HIV epidemic. Ad infections with the 51 different serotypes recognised to date have few pathognomonic signs and symptoms, and thus require a variety of laboratory-based procedures to confirm infection. These viruses have the ability to target various organs with relative serotype specificity and can cause diverse manifestations including serious life-threatening diseases characteristic of the organs involved. Ads have cytolytic and immunoregulatory properties. The clinical dilemma remains the prompt recognition of Ad-related disease, the differentiation of Ad infection from Ad disease and the differentiation from other causative agents. Since the armamentarium of effective antiviral agents available to treat Ads is unproven by controlled trials and the virus is often not acquired de novo, it is difficult to prevent reactivation in immunodeficient hosts or new acquisition from donor organs. Timely discontinuation of immunosuppressive agents is necessary to prevent morbid outcomes. The clinical diseases, diagnostic tests, antiviral agents and biological aspects of the Ads as pathogens in immunocompromised patients are discussed in the context of this review. Some of the newer diagnostic tests are based on the well-studied molecular biology of Ads, which also have been attenuated by selective viral DNA deletions for use as vectors in numerous gene therapy trials in humans.

Fulminant adenovirus hepatitis following bone marrow transplantation. A case report and brief review of the literature

Adenovirus infections are frequently encountered in immunocompromised patients and transplant recipients. However, fulminant hepatic failure due to adenovirus infection as a fatal complication in bone marrow transplant recipients is extremely rare. We report a case of fulminant adenovirus hepatitis in a 21-year-old allogeneic bone marrow transplant recipient who subsequently died of the disease. The diagnosis was established by histologic and immunohistochemical examination of a liver biopsy and was confirmed by liver tissue and blood cultures.

Cidofovir for adenovirus infections after allogeneic hematopoietic stem cell transplantation: a survey by the Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation

Adenovirus is an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation and there is no established therapy. Cidofovir has in vitro efficacy against adenovirus. We performed a retrospective analysis of 45 patients treated with cidofovir for adenovirus from 10 centers. In total, 16 patients had definite adenovirus disease, 13 probable disease, and 16 asymptomatic infections. A total of 31 (69%) patients were successfully treated with cidofovir, 10 failed, and four were not evaluable owing to early death from other causes. Cidofovir therapy was successful in 10 patients with adenovirus disease, 10 patients with probable disease, and in 10 patients with asymptomatic infections. The overall survival at 28 days and 6 months after initiation of cidofovir therapy was 76 and 46%, respectively. Of the patients, 18 developed toxicity associated with cidofovir: 14 developed renal toxicity and four other types of toxicities. We conclude that cidofovir may be useful against adenovirus after allogeneic hematopoietic stem cell transplantation but additional studies are needed.

Adenovirus: an increasingly important pathogen in paediatric bone marrow transplant patients

Adenovirus is increasingly being recognised as a significant pathogen in children following bone marrow transplantation. The virus is endemic in the general paediatric population, and frequently causes severe disease in immunocompromised patients, especially children. Immune responses to adenovirus infection are not fully understood but T-cell responses appear to be important for recovery. Infections can affect a variety of organs with gastrointestinal and urinary tract diseases being the most common. When disseminated infection occurs, reported mortality rates are as high as 60%. The responses to treatment in immunocompromised patients have generally been disappointing. New molecular diagnostic techniques have meant that adenoviral infections can now be detected early, often before symptoms have developed. Clinicians now screen for adenovirus infection to allow early initiation of treatment. It is hoped that this approach, together with effective antiviral therapy, will reduce the deaths from this common virus in high-risk children.

Cyclic recovery of adenovirus in a stem cell transplant recipient: an inverse association with graft-versus-host disease

Adenovirus (AdV) infections have been increasingly recognized as significant pathogens that may cause severe morbidity and mortality among stem cell transplant (SCT) recipients. AdV can cause localized infections such as hemorrhagic cystitis (HC), pneumonia, hepatitis and also disseminated disease that can lead to death. We report a case of severe hemorrhagic cystitis in a SCT recipient who died 83 days after transplant. In this patient, AdV recovery was not constantly detected. In fact, fluctuations of the AdV detection in leukocytes and urine were observed by culture and PCR. When analyzing this viral cyclic recovery with different signs or symptoms in the patient, we observed an inverse association with the presence of acute graft-versus-host disease (GVHD). Whether these fluctuations represent donor-derived reactivity, indirectly manifested by the presence of GVHD, requires further study. This is the first case describing a dynamic pattern of AdV replication in leukocytes and urine samples from a patient with severe HC and the temporal correlation with GVHD.

Adenovirus infection in pediatric liver and intestinal transplant recipients: utility of DNA detection by PCR

To evaluate the incidence of adenovirus (AdV) infection in pediatric liver and intestinal transplant recipients, the records of patients with possible AdV infection were reviewed for demographic data, symptomatology, methods of diagnosis, treatment and outcome. To evaluate the impact of polymerase chain reaction (PCR) amplification and identification of AdV DNA as a diagnostic test, the incidence and outcome of AdV before and after the introduction of PCR were compared. Adenovirus infection was identified in 4.1% of liver recipients and 20.8% of intestinal transplant recipients. The overall incidence of AdV did not increase over time, even following the introduction of PCR for virus detection. The higher incidence of AdV in the pediatric intestinal transplant recipients may be attributed to the frequent application of PCR methodology to intestinal biopsy material. Detection of AdV by PCR was associated with reduced mortality compared with detection by culture, either because of earlier detection of invasive disease or because PCR detects the presence of latent as well as active AdV.

Acute Adenoviral Infection of a Graft by Serotype 35 Following Renal Transplantation

Adenoviral infections of immunocompetent patients usually present as self-limiting pharyngitis, gastroenteritis, urocystitis, or conjunctivitis. In immunosuppressed patients, development of the illness can be severe, even life-threatening or fatal, and therapeutical intervention is difficult. Previous case reports of adenoviral infections after kidney transplantation have described a symptomatology of hemorrhagic cystitis, fever, renal dysfunction, and rarely fatal systemic dissemination. Here we report on a 46-year-old female renal transplant recipient suffering from adenoviral serotype 35 nephritis of the donor organ 29 days after transplantation. In this case, the main symptoms of the adenoviral infection were high fever and progressive renal failure of the transplanted organ. At the peak of the clinical symptoms, owing to histological and immunohistochemical evaluations of a kidney biopsy, we were able to establish the diagnosis in time so that adequate therapy could be employed. Immunosuppression was reduced and modified, and a self-limiting course of the infection was observed, followed by significant improvement of graft function. Subsequent to histological diagnosis, adenoviral particles were isolated from urine and identified as adenovirus serotype 35. Adenoviral nephritis of the transplanted organ should be considered in the differential diagnosis of persistent anuria after kidney transplantation. Our case highlights the importance of applying all possible diagnostic techniques, including histological evaluation of renal biopsies.

Cytomegalovirus and adenovirus infections and diseases among 75 paediatric unrelated allogeneic bone marrow transplant recipients

Viral infections remain a major complication of allogeneic bone marrow transplantation. A population of children who underwent unrelated allogeneic bone marrow transplantation in a single centre has been followed-up for viral infections and diseases. We describe the detection of cytomegalovirus (CMV) and adenovirus among 75 children transplanted between 1989 and 2000. CMV was detected among 22 patients (29%) and adenovirus among 19 patients (25%); they were associated with clinical diseases in 10 and 8 patients, respectively. Four patients had adenovirus and CMV coinfection. The obvious risk factor for CMV infection is seropositivity of the recipient prior to transplantation. Adenovirus is detected significantly more frequently when conditioning regimen includes anti-thymocyte or anti-lymphocyte globulin. Diseases associated with adenovirus have been correlated with a significantly higher mortality rate, stressing the need for the implementation of a systematic virological survey for this virus and for the evaluation of therapeutic protocols including new molecules.

Use of polymerase chain reaction for diagnosis of disseminated adenovirus infection

We report a fatal case of disseminated adenovirus infection with fulminant hepatic failure in an 8-month-old child after peripheral blood stem cell transplantation. The virus was identified in blood, urine, respiratory aspirate and stool samples and was typed as adenovirus type 2 through PCR and sequencing of part of the hexon gene, with the use of degenerated consensus primers.

Adenovirus infections following allogeneic stem cell transplantation: incidence and outcome in relation to graft manipulation, immunosuppression, and immune recovery

Adenovirus infections occur in 5% to 21% of patients following stem cell transplantation (SCT), with an associated mortality of up to 50%. However, a lack of prospective studies has hampered further developments in the understanding and management of this infection in the posttransplantation setting. We prospectively studied the incidence and outcome of adenovirus infections after SCT using preemptive screening and a policy of reduction or withdrawal of immunosuppressive therapy if the virus was isolated. The incidence of adenovirus infection was 19.7% (15 of 76), and the virus was isolated exclusively in recipients of T-cell-depleted grafts. Patients receiving 50 or 100 mg alemtuzumab in vivo were at the greatest risk of adenovirus infection (45% probability) regardless of donor type, and this was related to the slower lymphocyte recovery. Six (40%) of the 15 adenovirus-infected patients developed adenovirus disease. Severe lymphocytopenia (less than 300/microL) at the time of first detection of adenovirus was a major risk factor for development of adenovirus disease (P =.001). In addition, failure to reduce immunosuppression (P =.04) and a positive result of adenovirus polymerase chain reaction (PCR) in blood at diagnosis (P =.01) were both associated with fatal adenovirus disease. On the basis of this study, we recommend active surveillance for adenovirus infection in T-cell-depleted SCT and withdrawal or reduction of immunosuppressive treatment, if possible, in patients with adenovirus infection. Preemptive antiviral therapy is warranted for patients with severe lymphocytopenia or positive blood PCR, and in those in whom immunosuppressive therapy cannot be reduced.

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.

Infectious risks and outcomes after stem cell transplantation: are nonmyeloablative transplants changing the picture?

PURPOSE OF REVIEW

Opportunistic infections contribute to morbidity and mortality after myeloablative allogeneic stem cell transplantation. The development of nonmyeloablative or toxicity-reduced conditioning regimens for allogeneic hematopoietic stem cell transplantation might change this picture significantly. These regimens are in general highly immunosuppressive, but effects on myelopoiesis and mucosal toxicities are usually reduced compared with myeloablative hematopoietic stem cell transplantation conditioning regimens. This review summarizes the infectious risks associated with each type of hematopoietic stem cell transplantation conditioning regimen, and presents the results of early clinical studies.

RECENT FINDINGS

Although the data are preliminary, the results of recent studies suggest that nonmyeloablative conditioning regimens may decrease the risks of bacterial infections associated with mucosal damage and persistent neutropenia; however, risks for late viral and fungal infections persist during severe graft versus host disease. Results of several case reports and series emphasize that therapeutic outcomes of infections may be improved in patients who receive nonmyeloablative conditioning regimens.

SUMMARY

Infectious risks and outcomes after hematopoietic stem cell transplantation appear to be in evolution given the introduction of alternative, nonmyeloablative conditioning regimens. Although infections remain a prominent cause of transplant-related mortality, the timing and types of infections may differ. Further studies are necessary to define appropriate preventative strategies, and to determine whether patients with ongoing infections might benefit from nonmyeloablative hematopoietic stem cell transplantation.

Viral infections in immunocompromised patients: what's new with respiratory viruses?

PURPOSE OF REVIEW

The leading cause of death in solid organ and hematopoietic stem cell transplant recipients is infection. The respiratory viruses, particularly respiratory syncytial virus, influenza, parainfluenza, adenovirus, and picornaviruses, are increasingly recognized as significant pathogens in these populations.

RECENT FINDINGS

Respiratory syncytial virus has again been found to be the most common of the respiratory viruses causing severe infections in transplant recipients. Advances in prevention, particularly with regard to infection control practices, and to lesser extent treatment have had a substantial impact on the frequency and outcomes of this infection. New studies have clarified the impact of influenza in the hematopoietic stem cell transplant recipients and have provided evidence to support the use of M2 and neuraminidase inhibitors for early treatment. The epidemiology of parainfluenza and adenovirus in transplant recipients has been clarified, although therapeutic modalities are still limited and understudied. New antiviral medications may bring improved outcomes of picornavirus infections in this population. Finally, a new virus, the human metapneumovirus, has recently been described and may be a significant respiratory pathogen in immunocompromised transplant recipients.

SUMMARY

Studies published over the past year have documented a new respiratory pathogen. They have also resulted in improved understanding of the epidemiology of all of the respiratory virus pathogens, and have contributed to improve management of respiratory syncytial virus and influenza infection in hematopoietic stem cell transplant and solid organ transplant recipients.

Intravenous ribavirin treatment for severe adenovirus disease in immunocompromised children

BACKGROUND

Adenovirus is an important cause of morbidity and mortality in the immunocompromised host. The incidence of severe adenovirus disease in pediatrics is increasing in association with growing numbers of immunocompromised children, where case fatality rates as high as 50% to 80% have been reported. There are no approved antiviral agents with proven efficacy for the treatment of severe adenovirus disease, nor are there any prospective randomized, controlled trials of potentially useful anti-adenovirus therapies. Apparent clinical success in the treatment of severe adenovirus disease is limited to a few case reports and small series. Experience is greatest with intravenous ribavirin and cidofovir. Ribavirin, a guanosine analogue, has broad antiviral activity against both RNA and DNA viruses, including documented activity against adenovirus in vitro. Ribavirin is licensed in aerosol form for the treatment of respiratory syncytial virus infection, and orally in combination with interferon to treat hepatitis C. Intravenous ribavirin is the treatment of choice for infection with hemorrhagic fever viruses. The most common adverse effect of intravenous ribavirin is reversible mild anemia. The use of cidofovir in severe adenovirus infection has been limited by adverse effects, the most significant of which is nephrotoxicity.

OBJECTIVE

We report our experience with intravenous ribavirin therapy for severe adenovirus disease in a series of immunocompromised children and review the literature.

DESIGN/METHODS

We retrospectively reviewed the medical records of 5 children treated with intravenous ribavirin for documented severe adenovirus disease. Two patients developed adenovirus hemorrhagic cystitis after cardiac and bone marrow transplants, respectively. The bone marrow transplant patient also received intravenous cidofovir for progressive disseminated disease. An additional 3 children developed adenovirus pneumonia; 2 were neonates, 1 of whom had partial DiGeorge syndrome. The remaining infant had recently undergone a cardiac transplant. Intravenous ribavirin was administered on a compassionate-use protocol.

RESULTS

Complete clinical recovery followed later by viral clearance was observed in 2 children: the cardiac transplant recipient with adenovirus hemorrhagic cystitis and the immunocompetent neonate with adenovirus pneumonia. The remaining 3 children died of adenovirus disease. Intravenous ribavirin therapy was well tolerated. Use of cidofovir in 1 child was associated with progressive renal failure and neutropenia.

DISCUSSION

Our series of patients is representative of the spectrum of immunocompromised children at greatest risk for severe adenovirus disease, namely solid-organ and bone marrow transplant recipients, neonates, and children with immunodeficiency. Although intravenous ribavirin was not effective for all children with severe adenovirus disease in this series or in the literature, therapy is unlikely to be of benefit if begun late in the course of the infection. Early identification, eg by polymerase chain reaction of those patients at risk of disseminated adenovirus disease may permit earlier antiviral treatment and better evaluation of therapeutic response.

CONCLUSIONS

Two of 5 children with severe adenovirus disease treated with intravenous ribavirin recovered. The availability of newer rapid diagnostic techniques, such as polymerase chain reaction, may make earlier, more effective treatment of adenovirus infection possible. Given the seriousness and increasing prevalence of adenovirus disease in certain hosts, especially children, a large, multicenter clinical trial of potentially useful anti-adenoviral therapies, such as intravenous ribavirin, is clearly required to demonstrate the most effective and least toxic therapy.

Abdominal infections in patients with acute leukaemia: a prospective study applying ultrasonography and microbiology

A prospective study of 62 chemotherapy-induced neutropenic episodes in patients with acute leukaemia was conducted to determine the incidence and causes of abdominal infections, and to assess the diagnostic value of the combined use of ultrasonography (US) and microbiology. Each patient underwent US of liver, gallbladder and complete bowel before chemotherapy, on days 2-4 after the end of chemotherapy and in cases of fever, diarrhoea or abdominal pain. US was combined with a standardized clinical examination and a broad spectrum of microbiological investigations. From January to August 2001, 243 US examinations were performed. The overall incidence of abdominal infectious diseases was 17.7% (11 out of 62, 95% confidence interval (CI): 9-29%). Four patients (6.5%) developed neutropenic enterocolitis; two of them died, two survived. Bowel wall thickening (BWT) > 4 mm in these four patients ranged from 5.8 to 23.6 mm and was detected only in one patient with mucositis. In three other patients (4.8%) Clostridium difficile, and in one patient (1.6%) Campylobacter jejuni, caused enterocolitis without BWT. Cholecystitis was diagnosed in three patients (4.8%) and hepatic candidiasis was strongly suspected in one patient. Abdominal infections caused by gastroenteritis viruses, cytomegalovirus (CMV) or Cryptosporidium were not observed. We conclude that in neutropenic patients with acute leukaemia receiving chemotherapy: (i) BWT is not a feature of chemotherapy-induced mucositis and should therefore be considered as sign of infectious enterocolitis; (ii) viruses, classic bacterial enteric pathogens (Salmonella, Shigella, Yersinia, Campylobacter, Aeromonas, Vibrio subsp., enterohaemorrhagic Escherichia coli) and Cryptosporidium have a very low incidence; and (iii) abdominal infections may be underestimated when US is not used in every patient with abdominal pain.

Quantification of adenovirus DNA in plasma for management of infection in stem cell graft recipients

We used a real-time polymerase chain reaction method for quantification of adenovirus to monitor the dynamics of viral DNA load in plasma in pediatric stem-cell graft recipients. Two cases are described to demonstrate that detection and quantification of the adenovirus DNA load at regular intervals may be important to document the stage of adenovirus infection, to make decisions on clinical intervention, and to accurately monitor the response to antiviral therapy.

Immunotherapy to reconstitute immunity to DNA viruses

Defects in cytotoxic T-lymphocyte (CTL) function after hemopoietic stem cell transplantation (HSCT) are associated with an increased frequency and severity of viral diseases. Initial investigations of viral infections in immunosuppressed mice and subsequent clinical studies of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in human stem cell transplant patients have suggested that adoptive transfer of virus-specific T cells may restore protective immunity and control established infections. Current efforts focus on optimizing adoptive immunotherapy approaches and developing strategies for generating T cells specific for multiple viruses to provide broader protection.

Epidemic of adenovirus-induced respiratory illness among US military recruits: epidemiologic and immunologic risk factors in healthy, young adults

Adenovirus (Ad)-induced acute respiratory illnesses resurged among civilian adults and selected military training populations in the United States during the late 1990s. We examined the epidemiologic and immunologic correlates of Ad-induced respiratory illnesses during a large outbreak at an Army basic training installation in southeast United States during a 9-day period in November 1997. A total of 79 recruits hospitalized with acute respiratory illnesses were evaluated during the outbreak period; confirmation of Ad infection by isolation of Ad-like cytopathic agents from throat cultures was detected in 71 (90%) of these patients. Serotyping of 19 (27%) of these 71 isolates identified the etiologic agent to be Ad type 4 (Ad4). In addition, 30 (81%) of 37 patients in whom paired sera were collected demonstrated significant increases (i.e., 4-fold or higher) in serum anti-Ad4 neutralizing antibodies. Anti-Ad4 immunity in new recruits was found to be very low (15 to 22%). A case-control study involving 66 of the 79 hospitalized cases and 189 non-ill controls from the same units was conducted. A lower risk of hospitalization for acute respiratory illnesses was documented for female recruits (odds ratio[OR] = 0.47, P <.05) whereas, a higher risk was noted for smokers (OR = 1.89, P <.05). Unit (training company) attack rates as high as 8 to 10% per week were documented and the outbreak quickly subsided after live, oral Ad types 4 and 7 vaccination was resumed in November 1997. Re-establishment of a military Ad vaccination program is critical for control of Ad-induced acute respiratory illnesses.

Respiratory virus infections in pediatric hematopoietic stem cell transplantation

Respiratory virus infections (RVI) have become an increasingly appreciated problem in the hematopoietic stem cell transplant (HSCT) population. A retrospective analysis of 274 patients undergoing 281 HSCT at St. Jude Children's Research Hospital from January 1994 through December 1997 was performed. Medical and clinical laboratory records were reviewed beginning at the onset of conditioning through the year following each HSCT, and the analysis was done for the first RVI only. Thirty-two (11%) of 281 HSCT cases developed a RVI during the first year post-HSCT. The most frequent cause of RVI was human parainfluenza virus type 3. Univariate analysis was performed to determine the association between risk factors and the cumulative incidence of RVI. Respiratory viruses are frequent causes of infections in the first year post-HSCT in the pediatric population. Only allogeneic transplant and the degree of acute or chronic graft versus host disease were found to be statistically significant risk factors for RVI.