"Cytomegalovirus disease" in renal allograft recipients: is human herpesvirus 7 a co-factor for disease progression?

Update on human herpesvirus 7 pathogenesis and clinical aspects as a roadmap for future research

Human herpesvirus 7 (HHV-7) is a common virus that is associated with various human diseases including febrile syndromes, dermatological lesions, neurological defects, and transplant complications. Still, HHV-7 remains one of the least studied members of all human betaherpesviruses. In addition, HHV-7-related research is mostly confined to case reports, while in vitro or in vivo studies unraveling basic virology, transmission mechanisms, and viral pathogenesis are sparse. Here, we discuss HHV-7-related literature linking clinical syndromes to the viral life cycle, epidemiology, and viral immunopathogenesis. Based on our review, we propose a hypothetical model of HHV-7 pathogenesis inside its host. Furthermore, we identify important knowledge gaps and recommendations for future research to better understand HHV-7 diseases and improve therapeutic interventions.

Risk factors and outcome of concurrent and sequential multiviral cytomegalovirus, Epstein-Barr virus, BK virus, adenovirus and other viral reactivations in transplantation

PURPOSE OF REVIEW

Reactivation of viral infections occurs frequently in immunosuppressed populations, particularly in solid organ (SOT) or allogeneic haematopoietic cell (HCT) transplant patients. Concurrent and sequential multivirus infections are common, yet risk factors and outcomes remain unclear. This review aims to identify the patients vulnerable to multivirus infections and characterize the impact of increased viral burden to formulate prevention and treatment strategies.

RECENT FINDINGS

Incidences of up to 89% in SOT and 36% in HCT have been reported for two viruses, and 32% in SOT and 28% in HCT for at least three viruses. Risk factors appear related to an increased burden of immunosuppression, with most viral coinfections occurring within 12 months of transplantation. Direct viral complications such as cytomegalovirus disease are more frequent in coinfected patients, with documented prolonged duration of viraemia, higher viral load and increased end-organ disease. Graft dysfunction, acute rejection and graft-vs.-host disease (GVHD) have also been associated. Increased mortality is reported in the HCT population.

SUMMARY

Multivirus infections occur in a significant proportion of transplant patients and is linked to immunosuppressive burden. There is increasing evidence that this leads to worse graft and patient outcomes. Further prospective studies are required to further comprehensively characterise viral epidemiology, mechanisms and treatment strategies to ameliorate this risk.

Comparing the application of mNGS after combined pneumonia in hematologic patients receiving hematopoietic stem cell transplantation and chemotherapy: A retrospective analysis

Rapid and accurate pathogen identification is essential for timely and effective treatment of pneumonia. Here, we describe the use of metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage (BALF) fluid to identify pathogens in patients with hematologic comorbid respiratory symptoms in a retrospective study with 84 patients. In the transplantation group, 8 cases (19.5%) and 47 cases (97.9%) were positive for BALF by conventional method detection and mNGS detection, respectively, and 6 cases (14.0%) and 41 cases (91.1%) in chemotherapy group, respectively. The detection rate of mNGS in both groups was significantly higher than that of conventional detection methods (all P<0.05). Pseudomonas aeruginosa and Streptococcus pneumoniae were the most common bacterial infections in the transplantation and chemotherapy groups, respectively. Aspergillus was the most common fungal infection in both groups. Human betaherpesvirus 5 (HHV-5), torque teno virus and human betaherpesvirus 7 (HHV-7) were the most common pathogen species in both groups. The most common type of infection in patients in the transplantation and chemotherapy groups was the mixed infection of bacteria-virus. Most patients in the transplantation group had mixed infections based on multiple viruses, with 42 cases of viral infections in the transplantation group and 30 cases of viral infections in the chemotherapy group, which were significantly higher in the transplantation group than in the chemotherapy group (χ2 = 5.766, P=0.016). and the mixed infection of virus-virus in the transplantation group was significantly higher than that in the chemotherapy group (27.1% vs 4.4%, P=0.003). The proportion of death due to pulmonary infection was significantly higher in the transplantation group than in the chemotherapy group (76.9% vs 16.7%, χ2 = 9.077, P=0.003). This study demonstrated the value of mNGS of BALF in improving the diagnosis and prognosis of hematologic comorbid pneumonia, helping patients to obtain timely and effective treatment, and giving guidance on the overall treatment plan for patients, with particular benefit for patients with hematologic chemotherapy comorbid pneumonia.

Evaluation of a new extraction platform in combination with molecular assays useful for monitoring immunosuppressed patients

BACKGROUND

In the immunosuppressed, detection of viral reactivation at the earliest convenience and molecular monitoring are of paramount importance. Nucleic acid extraction has a major impact on the reliability of results obtained from molecular assays.

OBJECTIVES

The aim of this study was to investigate the accuracy of the new EMAG^® nucleic acid extraction platform and to compare the performance of the new platform to that of the standard NucliSENS^® easyMAG^® instrument in the routine clinical laboratory.

STUDY DESIGN

For accuracy testing, reference material and for comparison studies, clinical specimens were used. In addition, a lab-flow analysis including estimation of hands-on time and that for automated extraction was performed.

RESULTS

When accuracy was tested, all 89 results obtained were found to be concordant with the results expected. When 648 clinical results were compared, 85.7% were found to be within ±0.5 log₁₀ unit, 9.5% between ±0.5 and ±1.0 log₁₀ unit, and 4.8% more than ±1.0 log₁₀ unit. The overall time required for nucleic acid extraction of 8 samples in parallel was 94 min for the fully automated extraction mode and 82 min for the partly automated mode with the new platform, and 73 min with the standard instrument. Hands-on time was found to be shorter with the new platform.

CONCLUSIONS

The extraction performance of both platforms was found to be similar for EDTA whole blood, BAL, and urine specimens. The total turn-around time for nucleic acid extraction was found to be longer with the EMAG^® platform, whereas hands-on time was reduced.

EBV, HCMV, HHV6, and HHV7 screening in bone marrow samples from children with acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common cancer in childhood worldwide and Mexico has reported one of the highest incidence rates. An infectious etiology has been suggested and supported by epidemiological evidences; however, the identity of the involved agent(s) is not known. We considered that early transmitted lymphotropic herpes viruses were good candidates, since transforming mechanisms have been described for them and some are already associated with human cancers. In this study we interrogated the direct role of EBV, HCMV, HHV6, and HHV7 human herpes viruses in childhood ALL. Viral genomes were screened in 70 bone marrow samples from ALL patients through standard and a more sensitive nested PCR. Positive samples were detected only by nested PCR indicating a low level of infection. Our result argues that viral genomes were not present in all leukemic cells, and, hence, infection most likely was not part of the initial genetic lesions leading to ALL. The high statistical power of the study suggested that these agents are not involved in the genesis of ALL in Mexican children. Additional analysis showed that detected infections or coinfections were not associated with prognosis.

Management of herpesvirus infections

Management of human herpesviruses remains a considerable clinical challenge, in part due to their ability to cause both lytic and latent disease. Infection with the Herpesviridae results in lifelong infection, which can reactivate at any time. Control of herpesviruses is by the innate and adaptive immune systems. Herpesviruses must evade the host innate immune system to establish infection. Once infected, the adaptive immune response, primarily CD8(+) T-cells, is crucial in establishing and maintaining latency. Latent herpesviruses are characterised by the presence of viral DNA in infected cells and limited or no viral replication. These characteristics provide a challenge to clinicians and those developing antiviral agents. The scope of this review is two-fold. First, to provide an overview of all antivirals used against herpesviruses, including their mechanism of action, pharmacokinetics, side effects, resistance and clinical uses. And second, to address the management of each of the eight herpesviruses both in the immunocompetent and immunocompromised host, providing evidence for clinical management and therapeutic options, which is important to the clinician engaged in the management of these infections.

Lymphotropic herpesvirus DNA detection in patients with active CMV infection - a possible role in the course of CMV infection after hematopoietic stem cell transplantation

BACKGROUND

The natural history of cytomegalovirus (CMV) infection and disease in transplant recipients prompts researchers to look for other factors contributing to this infection. The ubiquity of lymphotropic herpesviruses (EBV, HHV-6, and HHV-7) and the possibility of their activation during immunosuppression may suggest their participation in progression of CMV infection in patients after hematopoietic stem cell transplantation (HSCT).

MATERIAL/METHODS

The presence of CMV, EBV, HHV-6 and HHV-7 was confirmed through detection of viral DNA isolated from leukocytes. Allo-HSCT recipients (n=55) were examined repeatedly within the average period of 14±7.3 months post-transplant.

RESULTS

CMV DNA was detected in 24% of samples, while EBV, HHV-6 and HHV-7 were detected in 20%, 15% and 14% of samples, respectively. Based on the presence of CMV infection at particular time-points (months) after transplantation, the recipients were divided into 3 groups: Group I (N=15) with persistent infection, Group II (N=20) with transient infection, and Group III (N=20) without CMV infection. In Group I, the mean CMV load was significantly higher than in Group II, and the clinical condition of Group I patients was poorer. All these patients manifested clinical symptoms, and all had episodes of GvHD. All Group I patients developed multiple infections; EBV in 80%, HHV-6 in 47% and HHV-7 in 87% of patients. In the remaining groups, with the exception of HHV-6 in group II, the frequency of infected patients was lower. In addition, CMV presence was often preceded by another herpesvirus.

CONCLUSIONS

The results suggest that other herpesviruses, mainly HHV-7, could predispose CMV to cause chronic infection.

Herpes viruses in transplant recipients: HSV, VZV, human herpes viruses, and EBV

The herpes viruses are responsible for a wide range of diseases in patients following transplant, resulting from direct viral effects and indirect effects, including tumor promotion. Effective treatments and prophylaxis exist for the neurotropic herpes viruses HSV-1, HSV-2, varicella zoster virus, and possibly HHV-6. Antivirals seem to be less effective at prevention of the tumor-promoting effects of Epstein-Barr virus and HHV-8. Reduction in immunosuppression is the cornerstone to treatment of many diseases associated with herpes virus infections.

Simultaneous monitoring of CMV and human herpesvirus 6 infections and diseases in liver transplant patients: one-year follow-up

OBJECTIVE

The aim of this study was to simultaneously monitoring cytomegalovirus and human herpesvirus 6 active infections using nested-polymerase chain reaction and, together with clinical findings, follow the clinical status of patients undergoing liver transplant.

INTRODUCTION

The human β-herpesviruses, including cytomegalovirus and human herpesvirus 6, are ubiquitous among human populations. Active infections of human herpesvirus 6 and cytomegalovirus are common after liver transplantation, possibly induced and facilitated by allograft rejection and immunosuppressive therapy. Both viruses affect the success of the transplant procedure.

METHODS

Thirty patients submitted to liver transplant at the Liver Transplant Unit, at the Gastro Center, State University of Campinas, SP, Brazil, were studied prospectively from six months to one year, nested-polymerase chain reaction for cytomegalovirus and human herpesvirus 6 DNA detections. Two or more consecutive positive nested-polymerase chain reaction were considered indicative of active infection.

RESULTS

Active infection by cytomegalovirus was detected in 13/30 (43.3%) patients, median time to first cytomegalovirus detection was 29 days after transplantation (range: 0-99 days). Active infection by human herpesvirus 6 was detected in 12/30 (40%) patients, median time to first human herpesvirus 6 detection was 23.5 days after transplantation (range: 0-273 days). The time-related appearance of each virus was not statistically different (p = 0.49). Rejection of the transplanted liver was observed in 16.7% (5/30) of the patients. The present analysis showed that human herpesvirus 6 and/or cytomegalovirus active infections were frequent in liver transplant recipients at our center.

CONCLUSIONS

Few patients remain free of betaherpesviruses after liver transplantation. Most patients presenting active infection with more than one virus were infected sequentially and not concurrently. Nested-polymerase chain reaction can be considered of limited value for clinically monitoring cytomegalovirus and human herpesvirus 6.

Cytomegalovirus infection in critically ill patients: a systematic review

INTRODUCTION

The precise role of cytomegalovirus (CMV) infection in contributing to outcomes in critically ill immunocompetent patients has not been fully defined.

METHODS

Studies in which critically ill immunocompetent adults were monitored for CMV infection in the intensive care unit (ICU) were reviewed.

RESULTS

CMV infection occurs in 0 to 36% of critically ill patients, mostly between 4 and 12 days after ICU admission. Potential risk factors for CMV infection include sepsis, requirement of mechanical ventilation, and transfusions. Prolonged mechanical ventilation (21 to 39 days vs. 13 to 24 days) and duration of ICU stay (33 to 69 days vs. 22 to 48 days) correlated significantly with a higher risk of CMV infection. Mortality rates in patients with CMV infection were higher in some but not all studies. Whether CMV produces febrile syndrome or end-organ disease directly in these patients is not known.

CONCLUSIONS

CMV infection frequently occurs in critically ill immunocompetent patients and may be associated with poor outcomes. Further studies are warranted to identify subsets of patients who are likely to develop CMV infection and to determine the impact of antiviral agents on clinically meaningful outcomes in these patients.

Human herpesvirus 7 in pediatric hematopoietic stem cell transplantation

BACKGROUND

Little is known about the significance of human herpesvirus 7 (HHV-7) in pediatric hematopoietic stem cell transplantation (HSCT).

OBJECTIVE

To evaluate children post autologous and allogeneic HSCT, with a positive PCR or immunohistochemistry for HHV-7 either from blood, cerebrospinal fluid (CSF) or any other pathology specimen. Clinical data for these patients were collected examining symptoms and signs, engraftment, acute infectious complications, graft versus host disease (GVHD) where applicable, and survival.

RESULTS

Between June 1999 and June 2003, 265 HSCT were performed in The Hospital for Sick Children, Toronto, allogeneic (n = 163) and autologous (n = 102). Nine children were positive for HHV-7 at a median of 21 days (range 16-27 days) post-HSCT. All had allogeneic transplantation. The most common underlying diagnosis was acute leukemia and 7 had matched unrelated donor (MUD) transplantation. Eight of the nine patients had grade II-IV acute GVHD and all of them had multiple infectious episodes with fungal, bacterial and other viral pathogens. Although not fully attributed to HHV-7, the clinical syndrome varied from fever, vomiting and diarrhea to septic shock. Four patients died due to GVHD and sepsis.

CONCLUSION

HHV-7 was uncommon post-HSCT. It was associated with severe GVHD and sepsis secondary to severe immunosuppression.

Human Herpesvirus-6 and -7 After Lung and Heart–Lung Transplantation

BACKGROUND

The impact of herpesvirus-6 and -7 (HHV-6, HHV-7) activation in lung transplant recipients is still poorly understood. We report the appearance of HHV-6 and HHV-7 antigenemia after lung transplantation and evaluate the efficacy of anti-viral drugs against these viruses.

METHODS

Twenty-two lung or heart-lung recipients were monitored for HHV-6, HHV-7 and cytomegalovirus (CMV) during 12 post-operative months. HHV-6- and HHV-7-specific antigens and CMV pp65 antigens were analyzed in blood leukocytes and bronchoalveolar lavage fluid cells by monoclonal antibodies. Ganciclovir or valganciclovir prophylaxis for a minimum of 3 months was given to 19 recipients at risk for CMV infection.

RESULTS

HHV-6, HHV-7 and CMV antigenemia was detected in 20 (91%), 11 (50%) and 12 (55%) recipients (median 16, 31 and 165 days) after transplantation, respectively. HHV-6 antigenemia occurred in 15 (79%), HHV-7 antigenemia in 7 (37%) and CMV antigenemia in 1 (7%) of these patients during anti-viral prophylaxis. HHV-6 or HHV-7 antigenemia was frequently associated with CMV antigenemia, which was detected 3 to 12 months after transplantation. Ganciclovir or valganciclovir treatment of CMV infection was effective against the concomitant HHV-6 and HHV-7 antigenemia in 9 of 12 (75%) and 5 of 6 (83%) cases, respectively. One case of pneumonitis and 1 of encephalitis were temporally associated with HHV-6. No other clinical manifestations could be linked solely to HHV-6 or -7.

CONCLUSIONS

HHV-6 and -7 antigenemia was common and appeared early after lung transplantation. CMV prophylaxis was not able to prevent the appearance of HHV-6 and -7 antigenemia.

Emerging viral infections in transplantation

Viral infections are an important complication of transplantation. The introduction of more potent immunosuppressive agents over the past decade correlates with an increase in the rate of hospitalizations of transplant patients with infections. Specifically, viral infections have emerged as a major source of morbidity and mortality in transplantation. There are several potential intervention strategies in the face of emerging infections and it is likely that the approach will differ depending on the virus in question. These include viral surveillance and pre-emptive therapy, intervention of the transplant community, and policy change at the level of government, blood bank and organ procurement organizations. This review focuses on the emergence of the herpesviruses; HHV-6 and HHV-7. In addition, the issue of virus transmission through organ transplant is addressed with a discussion of West Nile virus and the rabies virus.

HHV-6 and HHV-7 antigenemia related to CMV infection after liver transplantation

BACKGROUND

Betaherpesviruses human herpesvirus-6 and -7 (HHV-6, HHV-7), which are closely related to cytomegalovirus (CMV), have been reported in transplant patients. In this retrospective study, we investigated the occurrence of HHV-6 and HHV-7 antigenemia in relation to symptomatic CMV infection after liver transplantation.

METHODS

Sample material from 64 adult liver transplant recipients was included in the study. The patients were monitored weekly for CMV, HHV-6, and HHV-7. CMV infections were diagnosed by pp65-antigenemia and viral cultures. Concomitantly HHV-6 and HHV-7 antigens were demonstrated in peripheral blood mononuclear cells by monoclonal antibodies against both variants A and B and immunoperoxidase staining. Altogether 540 post-transplant blood specimens were analyzed.

RESULTS

Nineteen patients (30%) developed symptomatic CMV pp65 antigenemia during the first 3 months (mean 33 days, range 5-62 days) post-transplantation and were treated with intravenous ganciclovir. Concurrent HHV-6 antigenemia was detected in 16/19 (median 9 days, range 6-24 days) and HHV-7 antigenemia 15/19 patients (median 17 days, range 5-58 days) after transplantation. HHV-6 appeared before CMV in most cases (12/16), HHV-7 usually together with CMV. In those cases that HHV-6 preceded CMV antigenemia, it also was a possible cause of graft dysfunction. HHV-7 and CMV were so closely overlapping, that no symptoms could solely be linked with HHV-7.

CONCLUSION

HHV-6 and HHV-7 antigenemia usually occurred together with symptomatic CMV infection after liver transplantation. HHV-6 preceded CMV, but HHV-7 appeared together with CMV. Further investigation of the clinical significance of HHV-6 and HHV-7 antigenemia in organ transplant patients is necessary.

The impact of early cytomegalovirus infection and disease in renal transplant recipients

Human cytomegalovirus (HCMV) infection is the single most frequent infectious complication in the early period after kidney transplantation. The HCMV load in blood, measured by HCMV PCR or the HCMV pp65 antigen test, is a predictor of HCMV disease in seropositive recipients. However, plasma virus load measurements are of only modest value in predicting the risk of HCMV disease in seronegative recipients of kidneys from seropositive donors. HCMV infection is an independent risk-factor for acute kidney graft rejection. There is also evidence that HCMV is associated with an increased long-term mortality and post-transplant diabetes mellitus. Whether pre-emptive or prophylactic therapy should be the preferred strategy is not yet decided. Some studies indicate that HCMV prophylaxis may reduce the risk of acute rejection, and thereby increase long-term graft survival in seronegative recipients of kidneys from seropositive donors.

Influence of Ganciclovir Prophylaxis on Citomegalovirus, Human Herpesvirus 6, and Human Herpesvirus 7 Viremia in Renal Transplant Recipients

In order to know the influence of ganciclovir (GCV) prophylaxis on cytomegalovirus (CMV) human herpesvirus (HHV)-6 and HHV-7 replication in renal transplant recipients, three groups were studies: 54 patients without GCV; 29, with short-term GCV prophylaxis (less than 30 days); and 51, with long-term GCV prophylaxis (more than 60 days). CMV viremia was more prevalent in the first group (74%, 55%, and 29%, respectively), but CMV replication was also found in 14 patients during therapy, in the other two groups. The antiviral did not affect the prevalence of HHV-6 (67.2%) or HHV-7 (76%), but HHV-6 viremia appeared later (42 +/- 31 vs 21 +/- 25/38 +/- 29 days posttransplant) and was shorter (29 +/- 30 vs 62 +/- 34/41 +/- 33 days) among patients with long-term GCV prophylaxis. On the other hand, CMV viremia was longer when HHV-6 replication was present (40 +/- 25 days vs 18 +/- 16 days). In addition, HHV-7 DNA was detected in all patients with CMV disease.

Viral infection in the renal transplant recipient

Viruses are among the most common causes of opportunistic infection after transplantation and the most important. The risk for viral infection is a function of the specific virus encountered, the intensity of immune suppression used to prevent graft rejection, and other host factors governing susceptibility. Viral infection, both symptomatic and asymptomatic, causes the "direct effects" of invasive disease and "indirect effects," including immune suppression predisposing to other opportunistic infections and oncogenesis. Rapid and sensitive microbiologic assays for many of the common viruses after transplantation have replaced, for the most part, serologic testing and in vitro cultures for the diagnosis of infection. Furthermore, quantitative molecular tests allow the individualization of antiviral therapies for prevention and treatment of infection. This advance is most prominent in the management of cytomegalovirus, Epstein-Barr, hepatitis B, and hepatitis C viruses. Diagnostic advances have not been accompanied by the development of specific and nontoxic anti-viral agents or effective antiviral vaccines. Vaccines, where available, should be given to patients as early as possible and well in advance of transplantation to optimize the immune response. Studies of viral latency, reactivation, and the cellular effects of viral infection will provide clues for future strategies in prevention and treatment of viral infections.

Detection of human herpesvirus 7 DNA by loop-mediated isothermal amplification

The reliability of loop-mediated isothermal amplification (LAMP), initially developed for the detection of human herpesvirus 7 (HHV-7), was evaluated in this study. Although a LAMP product was detected in HHV-7 DNA, neither HHV-6 nor human cytomegalovirus DNA produced a product. When agarose gel electrophoresis was used for the detection of LAMP products, the sensitivity of a 30-min HHV-7 LAMP reaction reached 250 copies/tube. The use of turbidity for the detection of the LAMP products gave a sensitivity of 500 and 250 copies/tube for 30- and 60-min reactions, respectively. Following these initial validation studies, clinical samples collected from two patients with primary HHV-7 infections were examined by HHV-7 LAMP. By use of agarose gel electrophoresis, HHV-7 LAMP products could be detected in acute-phase plasma samples but no LAMP product was detectable in convalescent-phase plasma samples from either patient. Since a turbidity assay is less sensitive than agarose gel electrophoresis, no HHV-7 LAMP product could be detected in plasma samples after a 30-min LAMP reaction. After a 60-min LAMP reaction, HHV-7 LAMP product could be detected in acute-phase plasma samples.

Genetic variation of glycoproteins B and H of human herpesvirus 7 in Hong Kong

Glycoprotein B (gB) and glycoprotein H (gH) of human herpesvirus 7 (HHV-7) are believed to play an important role in virus entry and as targets for host immune response. This study examined the genetic diversity of these glycoproteins among 90 HHV-7 isolates collected from different individuals in Hong Kong. Overall, both the gB and gH genes were found to be highly conserved. Nucleotide polymorphism was detected only at four positions of the gB-encoding region, and all of these were synonymous substitutions. Most (97.8%) Hong Kong isolates were of gB allele group C. Two isolates collected from a Pakistani family showed a novel sequence pattern that did not match known gB allele groups. This sequence pattern was detected consistently from serial samples collected from the same individual, indicating a stable genetic entity. The gH-encoding region exhibited nucleotide polymorphism at six positions. Three of these were nonsynonymous substitutions (codon 271 Lys --> Gln, codon 308 Gly --> Glu, codon 397 Asn --> Tyr). Most (84.4%) Hong Kong isolates were of the gH allele group B, and all others were of the gH allele group C. These data indicate the possibility of using gB or gH alleles as markers for studying world-wide population movements and genetics.

Human herpesvirus 7-associated meningitis and optic neuritis in a patient after allogeneic stem cell transplantation

A 9-year-old boy who received allogeneic stem cell transplantation began to vomit from day 10 after transplantation. In addition to vomiting, the patient had a fever (from day 26) and severe headache (from day 34). His cerebrospinal fluid (CSF) (day 41) demonstrated pleocytosis with an absence of leukemic cells. Although the patient's symptoms were resolved with further supportive care, abrupt onset of bilateral decreased vision occurred at day 54. He was diagnosed with bilateral optic neuritis, due to the presence of disc edema and redness. Concomitant with the occurrence of aseptic meningitis, the human herpesvirus 7 (HHV-7) antibody titer increased significantly in this patient. Although neither HHV-6 nor cytomegalovirus (CMV) DNA was detected in CSF collected at day 41, HHV-7 DNA was detected in the sample. Viral DNA was not detected in CSF collected at day 93.

Herpesvirus DNA is consistently detected in lungs of patients with idiopathic pulmonary fibrosis

On the basis of earlier reports associating Epstein-Barr Virus (EBV) with half of the cases of idiopathic pulmonary fibrosis (IPF), we hypothesized that chronic infection with EBV or a closely related herpesvirus would be detected in all cases of IPF. We tested lung specimens from 33 IPF patients (8 patients with familial IPF and 25 patients with sporadic IPF) and 25 patients with other diseases as controls for the presence of eight herpesviruses using PCR-based techniques. One or more of four herpesviruses (cytomegalovirus [CMV], EBV, human herpesvirus 7 [HHV-7], and HHV-8) were detected in 32 of 33 (97%) subjects with IPF and in 9 of 25 (36%) controls (P < 0.0001). CMV, EBV, and HHV-8 were found more frequently in IPF patients than in controls (P < 0.05, P < 0.001, and P < 0.01 respectively). Two or more herpesviruses were detected in 19 of 33 (57%) IPF patients and in 2 of 25 (8%) controls (P < 0.001). Two or more herpesviruses and HHV-8 were found more frequently in patients with sporadic IPF than in patients with familial IPF (P < 0.05 for both comparisons), and CMV was found less frequently in patients with sporadic IPF than in patients with familial IPF (P < 0.05). Immunohistochemistry for EBV or HHV-8 antigen showed viral antigen primarily in airway epithelial cells. These data support the concept that a herpesvirus could be a source of chronic antigenic stimulation in IPF.

Detection of simultaneous beta-herpesvirus infections in clinical syndromes due to defined cytomegalovirus infection

Human herpesvirus (HHV)-6 and HHV-7 are increasingly being recognized as emerging pathogens among transplant recipients. Using quantitative polymerase chain reaction assays, we demonstrate the presence of HHV-6 and/or HHV-7 in 18 of 20 episodes of clinically presumed or microbiologically confirmed cytomegalovirus (CMV) infection. Seventeen (89%) of 19 microbiologically confirmed cytomegalovirus (CMV)-infected patients had concomitant HHV-6 variant B (47%) and/or HHV-7 (63%) infection. The degree of HHV-6 coinfection was significantly correlated with hyperbilirubinemia while HHV-7 coinfection demonstrated a non-significant trend toward cytopenias. In one of the 20 episodes described herein, the 'viral syndrome' was due solely to HHV-7 infection; clinical and virological response was observed during intravenous ganciclovir therapy in this patient. While this study emphasizes the significance of HHV-6 and/or HHV-7 coinfection during episodes of CMV infection, it significantly highlights the novel observation of the causal role of HHV-7 (in the absence of HHV-6 and CMV) in a clinical illness presumed to be caused CMV. Thus, HHV-7 (and HHV-6) should be considered as a pathogen (or copathogen) in the viral syndromes following organ transplantation.

Correlation between CMV genotypes, multiple infections with herpesviruses (HHV-6, 7) and development of CMV disease in kidney recipients in Kuwait

The possible correlation between cytomegalovirus, human herpesvirus types 6, 7 and cytomegalovirus-related clinical symptoms was studied in kidney transplant patients in Kuwait. Cytomegalovirus infection was diagnosed using the pp65 antigenemia assay. DNA of cytomegalovirus was detected by nested polymerase chain reaction (nested-PCR). PCR was also used to amplify the genes coding for structural proteins of human herpesvirus-6 (240 bp) and human herpesvirus-7 (186 bp). Glycoprotein B genotypes of cytomegalovirus were determined by restriction fragment length polymorphism. The average number of cells positive for cytomegalovirus pp65 antigen showed a steady increase with the severity of the cytomegalovirus-related symptoms. Furthermore, cytomegalovirus pp65 antigen positivity was significantly more frequent among recipients of cadaver kidney (45.5%) than among those who received live related kidneys (22.6%). Cytomegalovirus gB genotype 1 was detected more frequently (P<0.036) in recipients with live related donor kidney (38%) than in patients of cadaver kidney (13%). The genome of human herpesvirus-6 was detected at the same rate in patients with or without cytomegalovirus-related symptoms. However, the genome of human herpesvirus-7 was detected significantly more frequently (P<0.0001) in asymptomatic patients (41.7%) than in recipients with symptomatic cytomegalovirus infection (17%). We conclude that cytomegalovirus gB genotypes are not associated with the outcome of a cytomegalovirus infection in kidney transplant patients, that human herpesvirus-6 does not play a role in cytomegalovirus pathogenesis and that the role of human herpesvirus-7 in cytomegalovirus-related morbidity in kidney recipients remains unclear.

Human herpesvirus-6 and -7 infections in transplantation

Human herpesvirus-6 (HHV-6) and human herpesvirus-7 (HHV-7) are ubiquitous in the human population and cause exanthem subitum, a benign disease seen in infancy. The viruses remain latent in the body after primary infection, and reactivate in immunocompromised patients. HHV-6 infection occurs in nearly 50% of all bone marrow and in 20-30% of solid-organ transplant recipients, 2-3 weeks following the procedure. It has been suggested that the viral infection and activation result in clinical symptoms, including fever, skin rash, pneumonia, bone marrow suppression, encephalitis, and rejection. In order to understand the viral infection in greater detail, several studies investigating the route of viral transmission and diagnostic procedures have been carried out. In contrast to studies of HHV-6 infection in organ-transplant recipients, the number of studies examining HHV-7 infection in these patients is limited. According to several recent studies, HHV-7 may act as a cofactor for cytomegalovirus disease in organ-transplant recipients.

Virus del herpes humano tipo 6 y tipo 7 en receptores de trasplantes

Recent years have witnessed a growing interest in the role of human herpesvirus (HHV) type 6 and type 7 as emerging pathogens or copathogens in transplant recipients. Both HHV-6 and HHV-7 belong to the beta-herpesvirus family and are closely related to another member of the family, cytomegalovirus. After the primary infection, these viruses remain latent in the human host and can reactivate after transplantation. Various clinical processes such as fever, rash, pneumonitis, encephalitis, hepatitis, and myelosuppression have been described in association with herpesvirus. Moreover, a growing body of evidence suggests that the major impact of HHV-6 and HHV-7 reactivation in transplantation is related to indirect effects, such as their association with cytomegalovirus disease, increased opportunistic infections, and graft dysfunction and rejection. The pathogenesis of HHV-6 and HHV-7 during the post-transplantation period, the methods used for their diagnosis, and the evaluation of antiviral drugs and strategies for their prevention and treatment are now the subject of extensive research.

Human herpesvirus 6: molecular biology and clinical features

Human herpesvirus 6 (HHV-6) exists as distinct variants HHV-6A and HHV-6B. The complete genomes of HHV-6A and HHV-6B have been sequenced. HHV-6B contains 97 unique genes. CD46 is the cell receptor for HHV-6, explaining its broad tissue tropism but its restricted host-species range. HHV-6 utilizes a number of strategies to down-regulate the host immune response, including molecular mimicry by production of a functional chemokine and chemokine receptors. Immunosuppression is enhanced by depletion of CD4 T lymphocytes via direct infection of intra-thymic progenitors and by apoptosis induction. Infection is widespread in infants between 6 months and 2 years of age. A minority of infants develop roseola infantum, but undifferentiated febrile illness is more common. Reactivation from latency occurs in immunocompromised hosts. Organ-specific clinical syndromes occasionally result, but indirect effects including interactions with other viruses such as human immunodeficiency virus type 1 and human cytomegalovirus or graft dysfunction in transplant recipients may be more significant complications in this population. Recent advances in quantitative PCR are providing additional insights into the natural history of infection in paediatric populations and immunocompromised hosts.

Beta-herpesvirus challenges in the transplant recipient

Cytomegalovirus (CMV) has major consequences after allogeneic stem cell and solid organ transplantation. CMV may cause significant morbidity and mortality, and monitoring to detect reactivation to reduce disease or management of end organ disease is associated with increased resource utilization. Two other members of the beta-herpesvirus family, human herpesvirus (HHV) type 6 and HHV-7, are increasingly recognized as important pathogens in transplant recipients, either by direct infection (e.g., encephalitis, hepatitis, or pneumonitis) or via interaction with CMV. In addition to direct effects of CMV infection, such indirect effects as an increased risk for bacterial and fungal infections or impaired graft acceptance and function are important research topics. Diagnosis and treatment of CMV infection is currently more advanced than for HHV-6 and HHV-7.

Human herpesvirus 7 in dermatology: what role does it play?

Human herpesvirus 7 (HHV-7) was discovered in 1989 as a new member of the beta-herpesvirus subfamily. Primary infection occurs early in life and manifests as exanthema subitum, or other febrile illnesses mimicking measles and rubella. Thus, HHV-7 has to be considered as a causative agent in a variety of macular-papular rashes in children. In addition, HHV-7 was found in some cases of other inflammatory skin disorders, such as psoriasis. There are controversial data on the detection of HHV-7 in pityriasis rosea, but so far there is not enough evidence for a pathogenetic association of HHV-7 with this exanthematic skin disease. Although HHV-7 can be found in some cases of Hodgkin's disease, there are no data supporting a direct causative role in this lymphoma type nor in other nodal or primary cutaneous lymphomas. In various epidemiologic forms of Kaposi's sarcoma, infection of monocytic cells with HHV-7 was demonstrated, which may indirectly influence tumor biology. In the context of immunosuppression, HHV-7 has recently been identified as an emerging pathogen in transplant recipients and may exacerbate graft rejection in renal transplant recipients. The ability of HHV-7 to induce cytokine production in infected cells could make HHV-7 an important pathogenetic co-factor in inflammatory and neoplastic disorders. Moreover, the restricted cellular tropism of HHV-7 may render this virus an interesting vector for gene therapy. Thirteen years after the discovery of HHV-7, there has been considerable progress in characterizing its genetic structure, virus-induced effects on infected host cells and in the development of diagnostic tools. Nevertheless, the role of HHV-7 in various skin diseases and the clinical manifestations of reactivation of HHV-7 infection have still to be defined.

CMV infection is usually associated with concurrent HHV-6 and HHV-7 antigenemia in liver transplant patients

Human herpesvirus 6 and 7 (HHV-6, HHV-7) have been recently reported in liver transplant patients. HHV-6 may cause fever, neurological disorders and hepatitis. The clinical significance of HHV-7 is less clear. HHV-6 and -7 are closely related to cytomegalovirus (CMV), and interactions between the viruses have also been suggested. In this study, we investigated the post transplant HHV-6 and -7 antigenemia was in relation to symptomatic CMV disease after liver transplantation. Consecutive 34 adult liver allograft recipients transplanted during 1999-2000 were included in the study. CMV infections were diagnosed by the frequent monitoring of pp65-antigenemia and by viral cultures. HHV-6 and -7 were demonstrated, by using immunoperoxidase staining and monoclonal antibodies against the virus specific antigens, in the mononuclear cells from the same blood specimens which were obtained for CMV pp65 monitoring. Altogether 322 blood specimens were analyzed. CMV disease was diagnosed in 12 (35%) patients during the first 3 months (first pp65 positive specimen mean 25 days, range 8-61 days) after transplantation. Concurrent HHV-6 antigenemia was detected in 10/12 (mean 14 days, range 6-22 days) and HHV-7 antigenemia in 9/12 patients (mean 25 days, range 10-89 days) after transplantation. HHV-6 usually appeared slightly before CMV. All CMV infections were successfully treated with ganciclovir and the CMV-antigenemia subsided. HHV-6 and -7 antigenemia also responded to the antiviral treatment, but more slowly than CMV. In conclusion, CMV infection was usually associated with HHV-6 and -7 antigenemia in liver transplant patients. The results support the suggestion that CMV, HHV-6 and -7 may have interactions. The clinical symptoms of CMV infection, may also be linked with HHV-6 or -7.

The impact of human herpesvirus-6 and -7 infection on the outcome of liver transplantation

Human herpesvirus (HHV)-6 and -7 are novel members of the beta-herpesvirus family that maintain latency in the human host after primary infection. Reactivation from latency and/or increased degree of viral replication occurs during periods of immune dysfunction. The clinical effect of HHV-6 and HHV-7 reactivation in recipients of liver transplants is now being recognized. Clinical illnesses such as fever, rash, pneumonitis, encephalitis, hepatitis, and myelosuppression have been described in a number of anecdotal reports. Moreover, a growing body of evidence suggests that the more important effect of HHV-6 and HHV-7 reactivation on the outcomes of liver transplantation may be mediated indirectly by their interactions with the other beta-herpesvirus-cytomegalovirus (CMV). Coinfection among these three beta-herpesviruses in clinical syndromes that were classically ascribed to be solely caused by CMV has been shown and has raised substantial interest in the potential role of HHV-6 and HHV-7 as copathogens in the direct and indirect illnesses caused by CMV. This article reviews the current scientific data on the role and the magnitude of impact of HHV-6 and HHV-7 infection on the outcomes of liver transplantation.

Human herpesvirus 6 and human herpesvirus 7: emerging pathogens in transplant patients

Human herpesvirus 6 (HHV-6) and HHV-7 are two recently identified beta-herpesviruses, genetically related to human cytomegalovirus (CMV). Infection with both viruses is common worldwide with rates of seropositivity in adults over 90%. Infection with both viruses usually occurs in early childhood. In this age group HHV-6 is a cause of febrile illness including exanthem subitum, and likewise, primary HHV-7 infection has been associated with febrile illness. Similar to the other human herpesviruses, in particular CMV, the viruses have the potential for enhanced pathogenicity in the immunocompromised host. Active infection with both viruses is common following bone marrow or solid organ transplantation, most likely through reactivation of recipient's virus or re-infection considering their high prevalence in the population. Both viruses can be detected by PCR in the peripheral blood of healthy individuals and although the significance of blood-borne transmission is not clear, a preliminary study suggested that it was not significant for HHV-6. However, there is growing evidence that these viruses may be medically important in the post-transplant period. In bone marrow transplant patients HHV-6 has been associated with a range of clinical disease including encephalitis, interstitial pneumonitis, early and late graft failure and bone marrow suppression. There is also growing evidence for potential interactions among the beta-herpesviruses in liver and renal transplant patients. HHV-6 infection has been associated with an increased risk of developing CMV disease and opportunistic infections and HHV-7 infection has also been linked to an increased risk of CMV disease.

Opportunistic infections after renal transplantation

Opportunistic infection is a serious clinical complication in patients receiving immunosuppressive therapy after kidney transplantation. This article deals with some of the possible infectious agents that were recently encountered at our transplantation centre in Düsseldorf, Germany. Opportunistic organsims such as human herpesviruses 6-8, polyomavirus, parvovirus B19, varicella zoster virus, Nocardia and Listeria monocytogenes are rare but severe complications that are presented in this overview. As a result of the use of new immunosuppresive drugs like tacrolimus and mycophenolate mofetil these infections are now seen more frequently, so they should always be included in differential diagnostic considerations. New diagnostic procedures and new treatment strategies should allow early detection and successful treatment of opportunistic infections in the majority of kidney transplant recipients.

Correlation between human herpesvirus 6 and 7 infections after living related liver transplantation

Human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) are closely related to each other. Interaction between the two viruses at the time of primary HHV-7 infection is suggested by in vivo and in vitro studies. However, interaction between the two viruses in organ transplant recipients has not been analyzed. We analyzed serially collected plasma samples obtained from 40 living related liver transplant recipients by serological assay (indirect immunofluorescence assay, IFA) and polymerase chain reaction (PCR). Significant increase or seroconversion of HHV-6 IgG and HHV-7 IgG antibody titers were observed in 45% and 58% of recipients respectively. Positive rate of IgM HHV-6 antibody increased up to 35% at 4 weeks after transplantation. However, no remarkable peak in the positive rate of HHV-7 IgM antibody was demonstrated. HHV-6 and HHV-7 DNA were detected in plasma in 15 (38%) and 16 (40%) of the 40 recipients respectively. HHV-6 DNA was detected in 10 (26%) of the 38 recipients at 2 weeks after transplantation. The positive rate of the virus genome in plasma gradually decreased after that time. HHV-7 DNA was detected in 5 (14%) of the 37 recipients at 2 weeks after transplantation; no obvious peak in the positive rate of HHV-7 DNA was demonstrated. Antibody responses involving both HHV-6 and HHV-7, including either a significant increase in IgG antibody titers or positive identification of IgM antibody were observed in 17 (43%) of the 40 recipients. Thirteen out of the 17 recipients demonstrated concurrent antibody response against both viruses. HHV-7 antibody response preceded the HHV-6 antibody response in 2 of the remaining 4 recipients, whereas the opposite was true in the other 2 recipients. Both HHV-6 and HHV-7 DNA were detected in 7 (18%) of the 40 recipients. In 4 of those 7 recipients, DNA from both viruses was concurrently detected, 3 of whom had HHV-7 DNA repeatedly detected after first detection of the virus DNA. The detection of HHV-7 DNA preceded the detection of HHV-6 DNA in 2 recipients, whereas HHV-6 DNA appeared first in 1 recipient.

Association of tumour necrosis factor alpha and interleukin 6 levels with cytomegalovirus DNA detection and disease after renal transplantation

Cytokines such as tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) are thought to be important in the pathogenesis of post-transplant cytomegalovirus (CMV) disease. CMV infection increases the production of TNF-alpha and IL-6. Conversely, TNF-alpha switches on the replication of CMV. To study the association of these two cytokines with CMV activity and disease, TNF-alpha and IL-6 levels were assayed in plasma samples taken serially from three groups of renal transplant recipients. Group A (n = 12) had CMV disease and syndrome; Group B (n = 11) had detectable CMV DNA in plasma or peripheral blood leucocytes without disease, i.e., presumed asymptomatic CMV infection, and Group C (n = 11) had no detectable CMV DNA nor disease. The median peak TNF-alpha levels in patients with CMV disease (Group A) were significantly higher than that in Group B or Group C (P < 0.02) whereas the median peak IL-6 levels in group C patients were significantly lower than that in group A (P < 0.04) or group B (P < 0.03). A TNF-alpha level of above 100 pg/ml was significantly associated with CMV disease and high plasma CMV load (> 10,000 copies/ml). IL-6 levels above 15 pg/ml were significantly associated with CMV DNA detection, but not with CMV disease or elevated CMV load. High levels of TNF-alpha or IL-6 were not associated with CMV donor/recipient serostatus, HHV-6 or HHV-7 DNA detection, immunosuppressive regimen or rejection episodes. The role of TNF-alpha in the pathogenesis of CMV disease deserves further investigation.

Human herpesviruses 6 and 7 in solid organ transplant recipients

The impact of cytomegalovirus, a member of the beta-herpesvirus subgroup of the Herpesviridae, on patients who have undergone transplantation cannot be overstated. However, in the last 15 years, 2 additional members of the human beta-herpesvirus family have been discovered: human herpesviruses 6 and 7 (HHV-6 and HHV-7). The impact of HHV-6 and HHV-7 is assessed, as is the well-being of transplant recipients. Also discussed is whether the data on the pathological consequences of infection warrant routine screening for these viruses in solid organ transplant recipients.

New developments in the management of cytomegalovirus infection and disease after renal transplantation

The clinical management of cytomegalovirus infection and disease in renal transplant recipients has recently been significantly improved with the availability of data on prophylaxis with oral ganciclovir and valacyclovir. In addition, significant progress in early diagnosis and the quantitation of viral load has been achieved. The influence of novel immunosuppressants on the clinical course of cytomegalovirus infection has been clarified to some extent by recent clinical data. The identification of risk factors for cytomegalovirus disease beyond seroconstellation and immunosuppression is an ongoing process that might lead to a more targeted use of antiviral agents, given the risk of ganciclovir resistance. The understanding of the effects of cytomegalovirus on long-term graft outcome still needs to be deepened in order to design cytomegalovirus-specific interventions to improve graft survival.

Human herpesvirus-6 and -7 in transplantation

Infections with the beta-herpesviruses human herpesvirus-6 (HHV-6) and human herpesvirus-7 (HHV-7) are ubiquitous in childhood. The immunosuppression secondary to organ or bone marrow transplantation together with posttransplantation management may favour viral replication and reactivation. HHV-6 and -7 induce immunosuppression by targeting lymphocytes, natural killer cells and monocytes. HHV-6 is commonly detected posttransplantation but variability in definitions of clinical syndromes related to this virus and detection methods have complicated understanding of the clinical relevance of HHV-6 posttransplantation. Clinical symptoms associated with HHV-6 include febrile illness, pneumonitis, hepatitis, encephalitis and bone marrow suppression. However, the majority of HHV-6 infections are asymptomatic. The incidence of HHV-7 infection and its clinical manifestations posttransplantation are even less well characterised. In addition, HHV-6 and HHV-7 are related to CMV disease or acute graft-versus-host disease and, indirectly, to increases in resource utilisation. Based on the potential relevance of these two beta-herpesviruses in transplant recipients, further studies are required to establish their real impact in transplantation. For this, sensitive and specific molecular diagnostic techniques allowing for the rapid detection and quantitation of virus and for the analysis of susceptibility to current antiviral agents are required.