Viral infections after renal transplantation

Long-Term Suppression of Circulating Proinflammatory Cytokines in Multiple Sclerosis Patients Following Autologous Haematopoietic Stem Cell Transplantation

Autologous haematopoietic stem cell transplantation (AHSCT) is a therapeutic option for haematological malignancies, such as non-Hodgkin’s lymphoma (NHL), and more recently, for autoimmune diseases, such as treatment-refractory multiple sclerosis (MS). The immunological mechanisms underlying remission in MS patients following AHSCT likely involve an anti-inflammatory shift in the milieu of circulating cytokines. We hypothesised that immunological tolerance in MS patients post-AHSCT is reflected by an increase in anti-inflammatory cytokines and a suppression of proinflammatory cytokines in the patient blood. We investigated this hypothesis using a multiplex-ELISA assay to compare the concentrations of secreted cytokine in the peripheral blood of MS patients and NHL patients undergoing AHSCT. In MS patients, we detected significant reductions in proinflammatory T helper (Th)17 cytokines interleukin (IL)-17, IL-23, IL-1β, and IL-21, and Th1 cytokines interferon (IFN)γ and IL-12p70 in MS patients from day 8 to 24 months post-AHSCT. These changes were not observed in the NHL patients despite similar pre-conditioning treatment for AHSCT. Some proinflammatory cytokines show similar trends in both cohorts, such as IL-8 and tumour necrosis factor (TNF)-α, indicating a probable treatment-related AHSCT response. Anti-inflammatory cytokines (IL-10, IL-4, and IL-2) were only transiently reduced post-AHSCT, with only IL-10 exhibiting a significant surge at day 14 post-AHSCT. MS patients that relapsed post-AHSCT exhibited significantly elevated levels of IL-17 at 12 months post-AHSCT, unlike non-relapse patients which displayed sustained suppression of Th17 cytokines at all post-AHSCT timepoints up to 24 months. These findings suggest that suppression of Th17 cytokines is essential for the induction of long-term remission in MS patients following AHSCT.

Human Vascular Pericytes and Cytomegalovirus Pathobiology

Pericytes are multipotent cells of the vascular system with cytoplasmic extensions proximal to endothelial cells that occur along the abluminal surface of the endothelium. The interactions between endothelial cells and pericytes are essential for proper microvascular formation, development, stabilization, and maintenance. Pericytes are essential for the regulation of paracellular flow between cells, transendothelial fluid transport, angiogenesis, and vascular immunosurveillance. They also influence the chemical composition of the surrounding microenvironment to protect endothelial cells from potential harm. Dysregulation or loss of pericyte function can result in microvascular instability and pathological consequences. Human pericytes have been shown to be targets for human cytomegalovirus (HCMV) infection and lytic replication that likely contribute to vascular inflammation. This review focuses on human vascular pericytes and their permissiveness for HCMV infection. It also discusses their implication in pathogenesis in the blood⁻brain barrier (BBB), the inner blood⁻retinal barrier (IBRB), the placenta⁻blood barrier, and the renal glomerulus as well as their potential role in subclinical vascular disease.

Mesangial cells, specialized renal pericytes and cytomegalovirus infectivity: Implications for HCMV pathology in the glomerular vascular unit and post-transplant renal disease

Background

Human Cytomegalovirus (HCMV) infection is problematic after kidney transplantation. Human mesangial cells along with human glomerular endothelial cells and podocytes constitute the renal glomerular vascular unit (GVU). HCMV infection of the GVU is poorly understood.

Methods

GVU cells infectivity was analysed by microscopy and immunofluorescence. Cytokines profiles were measured by Luminex assays. Renal tissue analysis for HCMV infection was performed by immunohistochemistry.

Results

Mesangial cells and glomerular endothelial cells but not podocytes were permissive for both lab adapted and clinical strains of HCMV. Luminex analysis of cytokines expressed by mesangial cells exposed to the SBCMV clinical strain was examined. A Tricell infection model of the GVU maintains >90% viability with a unique cytokine profile. Finally, we show αSMA stained mesangial cells permissive for HCMV in renal tissue from a transplant patient.

Conclusions

HCMV infection of mesangial cells induces angiogenic and proinflammatory cytokines that could contribute to glomerular inflammation.

A 36-Year-Old Renal Transplant Recipient Female with Leg Ulcer: A Case Report and Brief Review

BACKGROUND

Opportunistic infections are common in organ transplant recipients. After 6 months of transplantation, patients have the highest risk of opportunistic infections such as cryptococcosis.

CASE PRESENTATION

The report presents the case of a 36-year-old female renal transplant recipient, with complaints of few subcutaneous painful and warm nodules and large, warm, erythematous, nontender plaques on the mildly edematous right leg and ankle. Incisional biopsy of the subcutaneous nodule over the leg showed panniculitis with small- to medium-sized vasculitis associated with round yeast forms, and culture of the fragments revealed C. neoformans var. grubii.

CONCLUSIONS

This article also reviews in brief the treatment of this rare complication. Reviewing the literature showed that since the cryptococcal cutaneous lesions are often nonspecific, the clinical picture solely is not enough to construct a definite diagnosis and there must be a high clinical suspicion.

Hemorrhagic Herpes Simplex Virus Type 1 Nephritis: An Unusual Cause of Acute Allograft Dysfunction

Interstitial nephritis due to viruses is well-described after solid organ transplantation. Viruses implicated include cytomegalovirus; BK polyomavirus; Epstein-Barr virus; and, less commonly, adenovirus. We describe a rare case of hemorrhagic allograft nephritis due to herpes simplex virus type 1 at 10 days after living donor kidney transplantation. The patient had a favorable outcome with intravenous acyclovir and reduction of immunosuppression.

Management of Opportunistic Infections in Solid-Organ Transplantation

Solid-organ transplantation is often the last alternative in many patients with end-stage organ disease. Although advances in immunosuppressive regimens, surgical techniques, organ preservation, and overall management of transplant recipients have improved graft and patient survival, infectious complications remain problematic. Bacterial, fungal, viral, and parasitic infections are implicated after transplantation depending on numerous factors, such as degree of immunosuppression, type of organ transplant, host factors, and period after transplantation. Proper prophylactic and treatment strategies are imperative in the face of chronic immunosuppression, nosocomial and community pathogens, emerging drug resistance, drug-drug interactions, and medication toxicities. This review summarizes the pathophysiology, incidence, prevention, and treatment strategies of common post-transplant infections.

Resistance of dialyzed patients to erythropoietin

Resistance to recombinant human erythropoietin is a common condition in dialyzed patients with chronic kidney disease and is associated with more hospitalizations, increased mortality and frequent blood transfusions. The main cause of hyporesponsiveness to recombinant human erythropoietin in these patients is iron deficiency. However, a high proportion of patients does not respond to treatment, even to the use of intravenous iron, which indicates the presence of other important causes of resistance. In addition to the iron deficiency, the most common causes of resistance include inflammation, infection, malnutrition, inadequate dialysis, and hyperparathyroidism, although other factors may be associated. In the presence of adequate iron stores, other causes should be investigated and treated appropriately.

Parvovirus B19 (B19) and cytomegalovirus (CMV) infections and anti-erythropoietin (anti-EPO) antibodies in patients on dialysis hyporesponsive to erythropoietin therapy

BACKGROUND

Approximately 10% of patients receiving recombinant human erythropoietin (rHuEPO) do not respond to the treatment. We evaluated parvovirus B19 (B19) and cytomegalovirus (CMV) infections and antierythropoietin (anti-EPO) antibodies as potential causes of anemia in dialyzed patients, hyporesponsive to rHuEPO.

METHODS

Data from 120 dialyzed patients, receiving rHuEPO alfa, were collected: demographic characteristics, rHuEPO dose, duration of rHuEPO treatment and time on dialysis, etiology of chronic kidney disease and transfusion history. Serology and PCR were performed to address B19 and CMV infection status. An ELISA was developed to detect anti-EPO antibodies.

RESULTS

rHuEPO resistance correlated with high ferritin levels (p = 0.001) and short time on dialysis (p = 0.012). B19 DNA was found in 10 (8.3%) dialyzed patients and CMV DNA was detected in 33 (27.5%). There was no significant correlation between B19 infection and anemia,while a tendency of correlation between active CMV infection and hemoglobin levels or hematocrit value (p= 0.069 and p= 0.070, respectively) has been observed. Anti-EPO antibodies were not detected in any patient.

CONCLUSIONS

B19 infection is a rare complication in dialyzed patients and should be investigated after exclusion of other common causes, while CMV infection is rather common. The role of CMV infection in the hyporesponsiveness in dialyzed patients should be further evaluated in other studies. Our data suggest that anti-EPO antibodies are not involved in rHuEPO resistance in this population.

Codon usage bias in human cytomegalovirus and its biological implication

Human cytomegalovirus (HCMV) infection, a worldwide contagion, causes a serious disorder in infected individuals. Analysis of codon usage can reveal much molecular information about this virus. The effective number of codon (ENC) values, relative synonymous codon usage (RSCU) values, codon adaptation index (CAI), and nucleotide contents was investigated in approximately 160 coding sequences (CDS) among 17 human cytomegalovirus genomes using the software CodonW. Linear regression analysis and logistic regression were performed to explore the preliminary data. The results showed that, overall, HCMV genomes had low codon usage bias (mean ENC=47.619). However, the ENC of individual CDS varied widely and was distributed unevenly between host-related genes and viral-self-function genes (P=0.002, odds ratio (OR)=3.194), as did the GC content (P=0.016, OR=2.178). The ENC values correlated with CAI, GC content, and the nucleotide composing at the 3rd codon position (GC3s) (P<0.001). There was a significant variation in the codon preference that depended on the RSCU data. The predicted ENC curve suggested that mutational pressure, rather than natural selection, was one of the main factors that determined the codon usage bias in HCMV. Among 123 genes with known function, the genes related to viral self-replication and viral-host interaction showed different ENC and CAI values, and GC and GC3s contents. In conclusion, the detailed codon usage bias theoretically revealed information concerning HCMV evolution and could be a valuable additional parameter for HCMV gene function research.

Incidence of CMV-HCV coinfection in renal transplant recipient

The authors report a case of a 47-year-old cytomegalovirus (CMV) immunoglobulin G (IgG) seropositive male patient with end stage renal disease who received a live renal transplant from a CMV IgG seropositive donor. Six months post-transplantation, the patient presented with reduced renal allograft function associated with fever, severe breathlessness, new onset jaundice and pancytopenia. His CMV DNA PCR came positive. Hepatitis C virus (HCV) RNA PCR also came positive (genotype I) though anti-HCV test performed before and after transplantation was negative. The patient was treated with oral valganciclovir and showed improvement of his clinical condition and was subsequently discharged under supervised therapy. However, the patient could not be treated for HCV because of risk of renal allograft rejection. The authors suggest oral valganciclovir for management of CMV infection and proper detection and eradication of HCV before renal transplantation to avoid future complications and prolongation of allograft survival.

Intragraft cytomegalovirus protein expression is associated with reduced renal allograft survival

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for acute and chronic rejection of transplanted organs and is thought to mediate rejection indirectly.

METHODS

In this retrospective observational cohort study, early- and end-stage biopsies from renal allografts lost because of chronic allograft dysfunction (n = 29) were examined for CMV antigens and DNA using immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction.

RESULTS

CMV immediate-early and late proteins were present in 27 (93%) of 29 of the end-stage chronic allograft dysfunction biopsies and in 64% of the corresponding early biopsies but not in pretransplant biopsies from CMV-seronegative donors (n = 3). Graft survival time was reduced in patients with moderate or high CMV levels in the graft soon after transplantation compared with that in patients with no or low CMV levels in the graft. No significant difference was observed in serum creatinine obtained at the time of early biopsies.

CONCLUSIONS

We provide evidence that intragraft CMV protein expression is associated with end-stage chronic renal allograft dysfunction, that intragraft CMV levels increase as graft function deteriorates, and that CMV protein expression in the grafts soon after transplant is associated with reduced graft survival. Thus, CMV may have a pathological role in chronic renal allograft dysfunction.

An unusual case of CMV cutaneous ulcers in a renal transplant recipient and review of literature

Cytomegalovirus (CMV) infection involving the skin is rare. We present a case of a renal transplant recipient who developed fever and axillary, scrotal and penile skin ulcers after renal transplantation. The skin ulcers did not heal with antibiotics. The skin biopsy revealed CMV inclusion bodies, CMV antigen on immunohistochemistry and high CMV DNA copies. The patient was diagnosed with CMV cutaneous ulcers. The skin ulcers healed after treatment with intravenous ganciclovir and oral valganciclovir. The diagnosis of CMV disease should be considered in the febrile immunosuppressed patient with skin ulcers. The biopsy of the cutaneous lesions may provide the diagnostic clue in such patients.

Hemorrhagic cystitis secondary to adenovirus or herpes simplex virus infection following renal transplantation: four case reports

Viral infections are common complications following renal transplantation. However, there have been few reported cases of viral cystitis secondary to herpes simplex virus or adenovirus infection. Herein, we have reported four cases of hemorrhagic cystitis secondary to infections with herpes simplex virus and adenovirus following renal transplantation. The etiology was adenovirus in three cases and herpes simplex virus in the remaining case. In all four cases, the primary cause of the renal dysfunction was diabetic nephropathy. All four patients presented with a clinical profile characterized by dysuria, pollakiuria, macroscopic hematuria, and graft dysfunction. Three of the four patients developed these symptoms within the first 3 months after renal transplantation. In all four cases, there was an increase, albeit slight, in creatinine levels, which returned to normal or near-normal values upon resolution of the symptoms. Acute cellular rejection was observed in only one case. Although rare, hemorrhagic cystitis secondary to infection, which typically occurs early in the posttransplant period, causes pronounced symptoms. The infection appears to be self-limiting, resolving completely within 4 weeks.

Case of adult mumps infection after renal transplantation

Viruses are the most common cause of opportunistic infections, important complications of transplantation. Mumps infection in renal transplant recipients is uncommon. This report focused on a 23-year-old woman who received immunosuppressive therapy based on tacrolimus, prednisolone, and mycophenolate mofetil for renal transplantation. Sixteen months after transplantation, she was admitted with pain and swelling in both infra-auricular areas. Laboratory findings demonstrated positive mumps IgM and IgG antibodies and an increased serum amylase level. Computed tomography revealed both parotid glands to be diffusely enlarged. After the diagnosis of mumps parotitis, the patient's immunosuppression was reduced and the clinical course was satisfactory.

Effect of cytomegalovirus prophylaxis with acyclovir on renal transplant survival

It is recognized that cytomegalovirus (CMV) infection in transplant recipients may lead to graft loss. Prophylaxis with acyclovir has therefore gained widespread acceptance, but the debate on whether this intervention improves long term graft survival continues. All patients who received renal grafts at the National Renal Transplant Centre, Dublin, between January 1992 and December 1999 were retrospectively analyzed. During this time period, patients who were CMV positive and/or had received grafts from CMV-positive donors were administered prophylactic oral acyclovir 800 mg thrice daily, adjusted for calculated creatinine clearance, from the first day post-transplantation. This treatment was continued for three months unless the graft failed or the patient developed CMV disease or died. Graft and patient outcomes were compared in recipients who received acyclovir with those who did not. Over the study period, 935 patients received renal transplants in our center, of whom 487 were administered acyclovir. The incidence of CMV disease was 3.3 cases per 100 patients per annum in those who required prophylaxis. Despite prophylaxis, graft outcomes were found to be significantly worse (p value < 0.001) in the group that qualified for acyclovir. We conclude that acyclovir provides incomplete protection from the negative impact of CMV on graft survival.

Deletion of open reading frame UL26 from the human cytomegalovirus genome results in reduced viral growth, which involves impaired stability of viral particles

We previously showed that open reading frame (ORF) UL26 of human cytomegalovirus, a member of the US22 multigene family of betaherpesviruses, encodes a novel tegument protein, which is imported into cells in the course of viral infection. Moreover, we demonstrated that pUL26 contains a strong transcriptional activation domain and is capable of stimulating the major immediate-early (IE) enhancer-promoter. Since this suggested an important function of pUL26 during the initiation of the viral replicative cycle, we sought to ascertain the relevance of pUL26 by construction of a viral deletion mutant lacking the UL26 ORF using the bacterial artificial chromosome mutagenesis procedure. The resulting deletion virus was verified by PCR, enzyme restriction, and Southern blot analyses. After infection of human foreskin fibroblasts, the UL26 deletion mutant showed a small-plaque phenotype and replicated to significantly lower titers than wild-type or revertant virus. In particular, we noticed a striking decrease of infectious titers 7 days postinfection in a multistep growth experiment, whereas the release of viral DNA from infected cells was not impaired. A further investigation of this aspect revealed a significantly diminished stability of viral particles derived from the UL26 deletion mutant. Consistent with this, we observed that the tegument composition of the deletion mutant deviates from that of the wild-type virus. We therefore hypothesize that pUL26 plays a role not only in the onset of IE gene transcription but also in the assembly of the viral tegument layer in a stable and correct manner.

Herpes simplex and varicella zoster viruses: forgotten but not gone

Herpesvirus infections are common complications of organ transplantation. The most frequent herpesvirus infections are caused by cytomegalovirus (CMV), herpes simplex (HSV) and varicella zoster (VZV). Despite expansion of the therapeutic armamentarium, HSV and VZV continue to cause morbidity and occasional mortality in transplant recipients. Here we review the incidence and risk factors for HSV and VZV disease, their clinical presentation, effects of newer immunosuppressive regimens and prophylaxis for HSV and VZV in solid organ transplant recipients.

Polymorphisms at exon 4 of p53 and the susceptibility to herpesvirus types 6 and 1 infection in renal transplant recipients

In order to replicate their own genome in the host nucleus, herpesviruses have to overcome the barrier presented by p53 gene. Variants of codon 72 and codon 47 of exon four decrease the ability of p53 to induce apoptosis. In order to investigate the influence of this germline inheritance on the susceptibility to herpesvirus type 6 (HHV6) and 1 (HHV1) infection, we examined 78 renal transplant recipients and 151 controls. HHV6 infection was more frequent among the renal transplant patients (35.89%) than in the control population (11.25%) (P < 0.001). HHV1 infection rate was similar in renal transplant patients (7.28%) and controls (2.56%). HHV6-positive cases were more frequent among patients with codon 72 of p53 variants (60.71%) than among wild-type p53 patients (28.20%) (P = 0.001) despite the higher frequency of codon 72 of p53 wild-type variant in renal transplant patients compared with controls (64.1% vs. 36.4%; P < 0.001). The presence of a codon 72 of p53 germline variant genotype increased the risk for HHV6 infection more than five times (OR = 5.479; 95% CI = 1.992-15.069). Our data suggest that codon 72 of p53 polymorphism genotyping may be useful to screen for patients at higher risk for post-transplant infections hence identifying individuals that could benefit from preventive treatment.

Viral infections affecting the skin in organ transplant recipients: epidemiology and current management strategies

Viral skin infections are common findings in organ transplant recipients. The most important etiological agents are the group of human herpesviruses (HHV), human papillomaviruses (HPV), and molluscum contagiosum virus. HHV that are important in this group of patients are herpes simplex virus (HSV) types 1 and 2, varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), HHV-6 and -7, and HHV-8, which causes Kaposi sarcoma (KS). HSV infections are characterized by their ability to establish latency and then reactivate at a later date. The most common manifestations of HSV infection in organ transplant recipients are mucocutaneous lesions of the oropharynx or genital regions. Treatment is usually with acyclovir, valaciclovir, or famciclovir. Acyclovir resistance may arise although the majority of acyclovir-resistant strains have been isolated from AIDS patients and not organ transplant recipients. In such cases, alternatives such as foscarnet, cidofovir, or trifluridine may have to be considered. VZV causes chickenpox as well as herpes zoster. In organ transplant recipients, recurrent herpes zoster can occur. Acute chickenpox in organ transplant patients should be treated with intravenous acyclovir. CMV infection occurs in 20-60% of all transplant recipients. Cutaneous manifestations, which include nonspecific macular rashes, ulcers, purpuric eruptions, and vesiculobullous lesions, are seen in 10-20% of patients with systemic infection and signify a poor prognosis. The present gold standard for treatment is ganciclovir, but newer drugs such as valganciclovir appear promising. EBV is responsible for some cases of post-transplant lymphoproliferative disorder, which represents the greatest risk of serious EBV disease in transplant recipients. HHV-6 and HHV-7 are two relatively newly discovered viruses and, at present, the body of information concerning these two agents is still fairly limited. KS is caused by HHV-8, which is the most recently discovered lymphotrophic HHV. Iatrogenic KS is seen in solid-organ transplant recipients, with a prevalence of 0.5-5% depending on the patient's country of origin. HPV is ubiquitous, and organ transplant recipients may never totally clear HPV infections, which are the most frequently recurring infections in renal transplant recipients. HPV infection in transplant recipients is important because of its link to the development of certain skin cancers, in particular, squamous cell carcinoma. Regular surveillance, sun avoidance, and patient education are important aspects of the management strategy.

Systemic Herpes Simplex Virus Infection Following Cadaveric Renal Transplantation: A Case Report

Herpes simplex virus (HSV) infection usually occurs in immunocompromised or severely debilitated patients. It is not so common in patients with renal transplants. The diagnosis can only be made histologically. It usually occurs during or shortly after treatment of graft rejection with high-dose steroids. We have recently experienced a case of HSV esophagitis and nephropathy in the renal allograft biopsy, which was identified by histology, immunostaining, and electron microscopy. A 43-year-old woman underwent cadaveric renal transplantation with cyclosporine and prednisolone treatment. Twelve months later, she developed renal insufficiency and proteinuria. Allograft renal biopsy showed some evidence of acute rejection. She was treated with 3 successive days of methylprednisolone (1.0 g/d) intravenously and continued tapering of steroids. Three weeks after steroid pulse therapy, she had throat pain, oral cavity ulcer, dysphagia, and febrile sensation. Esophagoscopy revealed multiple confluent ulcers in the whole esophagus, and biopsy showed enlarged epithelial cells with prominent nuclei. Immunohistochemically, the epithelial cells were positive with a monoclonal antibody to HSV type 1. She was started on acyclovir intravenously, which was continued for a week. After a week, her symptoms began to improve and repeat endoscopy showed no residual esophagitis. A renal allograft infection with HSV can persist in heavily immunosuppressed patients with recurrent rejection episodes. HSV mainly affects tubular cells causing necrosis, a major reason for functional deterioration. A biopsy is required for diagnosis.

Strategies for minimizing immunosuppression in kidney transplantation

Immunosuppression remains the cause of most morbidity following organ transplantation. However, its use is also responsible for the outstanding graft and patient survival rates commonplace in modern transplantation. Thus, the predominant challenge for transplant clinicians is to provide a level of immunosuppression that prevents graft rejection while preserving immunocompetence against environmental pathogens. This review will outline several strategies for minimizing or tailoring the use of immunosuppressive drugs. The arguments for various strategies will be based on clinical trial data rather than animal studies. A distinction will be made between conventional immunosuppressive drug reduction based on over-immunosuppression, and newer induction methods specifically designed to lessen the need for chronic immunosuppression. Based on the available data we suggest that most patients can be transplanted with less immunosuppression than is currently standard.

Hemorrhagic adenovirus cystitis after renal transplantation

PURPOSE

Viral infections are a major cause of postoperative morbidity and mortality after renal transplantation. Although cytomegalovirus, Epstein-Barr virus, and polyoma virus infections are common, there have been only a few reports of adenovirus infections.

MATERIALS AND METHODS

We report an unusual case of a patient with adenovirus-induced hemorrhagic cystitis (AHC). We also performed a comprehensive MEDLINE review to identify similar cases. We then compared the presentation, management, and outcome of all patients to identify patterns that may facilitate the diagnosis and management of AHC.

RESULTS

Review of the literature revealed 36 other reported cases of AHC in renal transplant recipients. Thirty-six of the 37 cases occurred within 1 year of transplantation. These patients presented with fever, dysuria, hematuria, and graft dysfunction. Thirty-four received high-dose steroids for treatment of symptoms of acute rejection. Four patients received antiviral medications. The infection was self-limited with mean duration of symptoms being 20 days. In all cases, serum creatinine returned to baseline or near baseline levels with resolution of symptoms.

CONCLUSIONS

Although uncommon, AHC usually presents within 1 year of renal transplantation with a consistent constellation of symptoms. The infection appears to be self-limited with full recovery in most patients within 4 weeks. The efficacy of antiviral medications could not be determined in this review.

Management of opportunistic infections in solid-organ transplantation

Solid-organ transplantation is often the last alternative in many patients with end-stage organ disease. Although advances in immunosuppressive regimens, surgical techniques, organ preservation, and overall management of transplant recipients have improved graft and patient survival, infectious complications remain problematic. Bacterial, fungal, viral, and parasitic infections are implicated after transplantation depending on numerous factors, such as degree of immunosuppression, type of organ transplant, host factors, and period after transplantation. Proper prophylactic and treatment strategies are imperative in the face of chronic immunosuppression, nosocomial and community pathogens, emerging drug resistance, drug-drug interactions, and medication toxicities. This review summarizes the pathophysiology, incidence, prevention, and treatment strategies of common posttransplant infections.

Significance of cytomegalovirus infection in renal transplantation

The aim of this study was to establish the relationship between vascular lesion chronic allograft nephropathy (CAN) and the presence of cytomegalovirus (CMV) in kidney transplanted patients. We studied 259 consecutive kidney transplant recipients with a minimum follow-up of 6 months; the induction immunosuppressive therapy included a calcineurin inhibitor, mycophenolate mofetil, steroids, and the use of an antilymphocyte serum if the patients developed delayed graft function. CMV early antigen detection (pp65) was performed on a weekly basis between days 30 and 90 post transplantation. Prophylactic treatment was administered in the donor +/recipient-risk group, and preemptive therapy delivered for positive antigenemia namely 3 days of intravenous [IV] gancyclovir [GCV] plus 11 days of oral therapy [in the case of infection], or 14 days of IV GCV [in the case of disease]). An acute kidney allograft rejection episode preceded CMV in 64.3% of the patients, and CMV preceded acute rejection in 35.7% of the cases. We conclude that CMV disease is an independent risk factor for CAN. CMV infection is probably associated with CAN, suggesting that the greater the viral load, the higher the risk of CAN. It may be advisable to perform universal prophylaxis to lower the viral load and CAN.

Sarcoma de Kaposi em paciente transplantada renal em uso de Fk-506

O Sarcoma de Kaposi (SK) é neoplasia maligna multicêntrica, cutânea e extracutânea, que tem sido descrita em pacientes transplantados renais que recebem terapia imunossupressora clássica. Este estudo descreve um caso de sarcoma de Kaposi em paciente transplantada renal recebendo FK-506, que surgiu 10 meses após o transplante.

Molecular diagnosis of viral infections in renal transplant recipients

PURPOSE OF REVIEW

To discuss biological and methodological aspects of virus infection monitoring in the renal transplant setting.

RECENT FINDINGS

New insights on the molecular pathogenesis of acute and persistent virus infections and rapid developments in real-time monitoring techniques are changing the current diagnostic routine. Accurate risk-assessment prior to transplantation and quantitative monitoring of parameters that reflect virus activity in the post-transplant period, including genome load fluctuations and aberrant viral mRNA or protein expression, provide early signs of undesired viral behaviour and allow pre-emptive therapeutic intervention. As opposed to prophylactic administration of antiviral drugs, a pre-emptive approach is more selective and will allow for antiviral immune responses to build, which may have a long-term beneficial effect. In addition, these virus-monitoring techniques allow for on-line assessment of therapeutic efficacy and rapid identification of emerging resistant strains. The combination of virus-monitoring techniques with rapid assessment of host immune responses using FACS and ELISPOT techniques, will improve overall patient management and long-term survival.

SUMMARY

Viral infections continue to be a significant complication in the transplant setting. Diagnostic monitoring allows timely and accurate therapeutic intervention. Knowledge of pathogenic mechanisms leading to disease is important for clinical decision making as well as for the selection of appropriate molecular parameters discriminating normal and disease-related activity of human pathogenic viruses. The increasing availability of effective antiviral drugs permits pre-emptive intervention that strongly depends on accurate viral monitoring procedures.

Noninvasive diagnosis of BK virus nephritis by measurement of messenger RNA for BK virus VP1 in urine

BACKGROUND

Polyoma virus type BK (BKV) nephritis has emerged as an important cause of renal allograft dysfunction and graft failure. Its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for BKV nephritis could improve clinical outcome.

METHODS

We obtained 25 urine specimens from 8 renal allograft recipients with biopsy-confirmed BKV nephritis, 31 samples from 28 recipients in whom BKV nephritis was excluded by allograft biopsy, and 74 specimens from 34 patients with stable allograft function. RNA was isolated from the urinary cells and reverse transcribed to complementary DNA. We designed gene-specific oligonucleotide primers and probes for the measurement of messenger RNA (mRNA) encoding BKV VP1 protein and a constitutively expressed 18S ribosomal RNA (rRNA) by real-time quantitative polymerase chain reaction. We explored the hypothesis that BKV VP1 mRNA levels predict BKV nephritis.

RESULTS

The levels of BKV VP1 mRNA but not the levels of 18S rRNA predicted BKV nephritis. Analysis involving the receiver operating characteristic curve demonstrated that BKV nephritis can be predicted with a sensitivity of 93.8% and a specificity of 93.9% with the use of a cutoff value of 6.5 x 10 BKV VP1 mRNA copy number per nanogram of total RNA ( <0.00001). In the receiver operating characteristic curve analysis, the calculated area under the curve was 0.949 (95% confidence interval, 0.912 to 0.987, <0.00001) for BKV VP1 mRNA levels and 0.562 (95% confidence interval, 0.417 to 0.708, >0.2) for 18S rRNA.

CONCLUSIONS

Measurement of BKV VP1 mRNA in urinary cells offers a noninvasive and accurate means of diagnosing BKV nephritis.

Non-nucleoside inhibitors of herpesviruses

While the treatment of herpes simplex virus with acyclovir and similar nucleoside analogues was one of the first success stories in antiviral chemotherapy, substantial unmet medical needs remain for herpesvirus diseases. In particular, the increasing numbers of immunosuppressed people due to AIDS, transplantation, cancer and aging has driven the need for improved antivirals to treat diseases caused by human cytomegalovirus (HCMV). Currently available drugs for the treatment of HCMV diseases are less than ideal agents due to issues of toxicity, modest efficacy and poor oral bioavailability. High throughput screening of large compound collections for inhibitors of specific viral enzymes or inhibition of viral growth in cell culture have identified a number of new HCMV inhibitors at several pharmaceutical companies. These compounds act by inhibition of novel molecular targets such as the viral protein kinase, viral protease and viral proteins involved in DNA cleavage/packaging. In addition, novel non-nucleoside inhibitors of the herpesvirus DNA polymerase have recently been described. This review will summarise some of these research efforts and will focus on non-nucleoside compounds that directly inhibit a viral process.

Sustained high frequencies of specific CD4 T cells restricted to a single persistent virus

Replication of cytomegalovirus (CMV) is largely controlled by the cellular arm of the immune response. In this study the CMV-specific CD4 T-cell response was characterized in a cohort of apparently healthy individuals. In 11% of all individuals, extremely high frequencies, between 10 and 40%, were found. High-level frequencies of CMV-specific CD4 T cells persisted over several months and were not the result of an acute infection. Specific T cells were oligoclonal and were phenotypically and functionally characterized as mature effector cells, with both cytokine-secreting and proliferative potential. These high-level frequencies do not seem to compromise the immune response towards heterologous infections, and no signs of immunopathology were observed. Whereas a large temporary expansion of virus-specific T cells is well known to occur during acute infection, we now show that extremely high frequencies of virus-specific T cells may continuously exist in chronic CMV infection without overtly compromising the remaining protective immunity.