Chiara Merlino

B19 virus infection in renal transplant recipients

BACKGROUND B19 virus infection with persistent anaemia has been reported in organ transplant recipients. Detection of B19 virus DNA in serum is the best direct marker of active infection. OBJECTIVE The present study evaluated the incidence and clinical role of active B19 virus infection in renal transplant recipients presenting with anaemia. STUDY DESIGN Forty-eight such recipients were investigated by nested PCR on serum samples. The controls were 21 recipients without anaemia. Active HCMV infection was also investigated as a marker of high immunosuppression. RESULTS AND CONCLUSIONS In 11/48 (23%) patients B19 virus DNA was demonstrated in serum versus only 1/21 (5%) of the controls. Ten of these 11 patients had already been seropositive at transplantation and active infection occurred in eight of them during the first 3 months after transplantation. The remaining patient experienced a primary infection 9 months after transplantation. Eight (73%) of these 11 patients displayed a concomitant HCMV infection and four (36%) showed increasing serum creatinine levels but none developed glomerulopathy; 3/11 (27%) recovered spontaneously from anaemia whereas 8/11 (73%) needed therapy. In conclusion, the relatively high occurrence (23%) of B19 virus infection in patients presenting with anaemia, suggests that it should be considered in the differential diagnosis of persistent anaemia in renal transplant recipients. Presence of the viral DNA should be assessed early from transplantation and the viral load should be monitored to follow persistent infection and better understand the relation between active infection and occurrence of anaemia, and to assess the efficacy of IVIG therapy and/or immunosuppression reduction in clearing the virus.

Interaction of Bartonella henselae with the Murine Macrophage Cell Line J774: Infection and Proinflammatory Response

ABSTRACT Bartonella henselae is the causative agent of cat scratch disease (CSD), a self-limiting condition characterized by a subacute regional lymphadenopathy that may develop into disseminated bartonellosis in immunocompromised subjects. Mice experimentally infected with B. henselaedisplay typical liver and spleen granulomas rich in T cells and macrophages. So far there are no data on the interaction between bartonellae and macrophages. In order to clarify this topic, we investigated the interaction of B. henselae with J774, a mouse macrophage cell line. Analysis of bacterial uptake by functional assays and transmission electron microscopy indicates that bartonellae can enter and survive inside J774. Entry occurred within 30 min postinfection and reached a plateau at 160 min. Infection of J774 was followed by a dose-dependent release of the proinflammatory cytokines tumor necrosis factor alpha, interleukin 1β (IL-1β), and IL-6. Bartonellae persisted intracellularly without loss of viability for at least 8 h, and their number slightly decreased 24 h postinfection. Gamma interferon (IFN-γ) treatment of J774 significantly decreased the number of recoverable bacteria at 8 and 24 h. This enhancement of macrophage bactericidal activity was associated with nitric oxide (NO) release and was prevented by the addition of the competitive inhibitor of NO synthesis NG-monomethyll-arginine. These findings suggest that IFN-γ-mediated activation of macrophages may be important for the clearing ofB. henselae infection and that anti-B. henselae microbicidal activity of IFN-γ-activated macrophages is mediated to a large extent by NO production.

Polyomavirus BK DNA quantification assay to evaluate viral load in renal transplant recipients

BACKGROUND Several studies have disclosed a correlation between polyomavirus BK (BKV) and interstitial nephritis in renal transplant recipients and its quantification in urine and serum is therefore required to assess the role of BKV infection in nephropathy. OBJECTIVE This paper describes a urine and serum BKV-DNA quantification protocol devised to evaluate the viral load. STUDY DESIGN Screening of samples containing > or =10(3)/ml viral genome copies by a semi-quantitative polymerase chain reaction (PCR) assay is followed by precise quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay. Generation of the competitor construct relied on the different sizes of wild-type and competitor amplicons. RESULTS AND CONCLUSIONS Screening by semi-quantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and -expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. The results obtained in BKV-DNA quantification in urine and serum samples from 51 renal transplant recipients (22 on treatment with tacrolimus (FK506) and 29 on cyclosporine A (Cy A)) are interesting: BKV-DNA findings (43.1%) in urine samples are in agreement with the BKV urinary shedding reported in literature (5-45%). With regard to immunosuppressive treatment, the percentage of activation of the infection (revealed by BKV-DNA detection in urine samples) in the two groups of therapy is similar (40.9% vs 44.8%). The observation that the viral load in urine is dissociated with that of serum suggests that both parameters should be investigated in evaluation of the pathogenetic role of BKV reactivation in renal transplant recipients. Moreover, our BKV-DNA quantification protocol could be used to monitor viral load in urine and serum samples from renal transplant recipients so as to detect those at risk of nephropathy and monitor their response to immunosuppression reduction therapy if it occurs.

Epstein-Barr Virus in Cutaneous T-Cell Lymphomas: Evaluation of the Viral Presence and Significance in Skin and Peripheral Blood

The importance of viral agents in the development of cutaneous T-cell lymphomas (CTCL) is still debated. For this purpose, we retrospectively evaluated the Epstein-Barr virus (EBV) presence in Sézary syndrome (SS), mycosis fungoides (MF), inflammatory dermatoses (ID), and healthy donors (HD) using different approaches: EBV-DNA was quantified in skin biopsies and peripheral blood using real-time PCR, EBV-encoded small RNA (EBER) transcripts were detected by in situ hybridization (ISH), and latent membrane protein1-2 antigens were detected by immunohistochemistry. Skin biopsies were EBV-DNA-positive in 8/30 (27%) SS, 7/71 (10%) MF, and 2/18 (11%) ID patients and in none of the 25 normal skin samples. Positive mRNA (EBER) signals, always confined to cerebriform T lymphocytes, were found in 5/30 SS patients (17%), whereas signals in all MF and ID patients were negative. The presence of EBV-DNA in skin and blood samples was associated with a significantly lower survival in MF/SS patients. In evaluating EBV serological status, most (>70%) SS, MF, and ID patients showed a serological reactivation demonstrated by the presence of anti-EA IgG. In conclusion, although the finding of EBV-DNA in CTCL does not prove its etiopathogenetic role and may be related instead to immunosuppression, our study demonstrates that it has prognostic relevance.

Human herpesvirus 7 detection by quantitative real time polymerase chain reaction in primary cutaneous T-cell lymphomas and healthy subjects: lack of a pathogenic role.

Background  Primary cutaneous T‐cell lymphomas (CTCLs) are a heterogeneous group of lymphomas where the tumour population emerges within a multiple subclone pattern. Mycosis fungoides (MF) and Sézary syndrome (SS) are characterized by the expansion of clonal CD4+/CD45RO+ memory T cells. Lymphomatoid papulosis (LyP) is a chronic, lymphoproliferative disorder included in the CD30+ primary CTCL spectrum. Several studies have suggested a role of viral infection for super‐antigenic activation of T lymphocytes; however, evidence of their association with CTCLs is still lacking. Human herpesvirus (HHV) 7 is a CD4+ T‐lymphotropic herpesvirus; its restricted cellular tropism and the ability to induce cytokine production in infected cells could make it an important pathogenic cofactor in lymphoproliferative disorders.

Human Polyomavirus BK Monitoring by Quantitative PCR in Renal Transplant Recipients

Objective: To study the relation between human polyomavirus BK (BKV) infection and the risk of developing nephropathy, we monthly investigated the BKV load in urine and serum samples from 15 renal transplant recipients during 6 months in relation with immunosuppressive treatment and renal function. Methods: BKV-DNA in serum samples was detected by nested PCR. BKV-DNA in urine and positive serum samples was quantified by a PCR protocol developed in our laboratory. Results: Fifty-three percent of the patients had quantifiable BKV-DNA both in urine and serum samples but there was no relation between viruria and viraemia. Seventy-five percent of the patients on FK506 therapy and 71.4% of those on CyA therapy showed activation of BKV infection. No patients developed interstitial nephritis during the study. In ten patients serum creatinine levels were <2 mg/dl for the whole study, even if 80% presented BKV viruria and/ or viraemia. On the other hand, in 4 patients serum creatinine levels reached higher values, but they were BKV viruria and/or viraemia negative during the study. Conclusions: Our results suggest that viruria and viraemia may reflect independent BKV reactivation in different tissues. The activation of the infection does not seem to be related to the type of immunosuppressive treatment nor to impairment of renal function. To better understand the pathogenetic role of BKV infection in renal transplant recipients further investigations are needed.

Variants of parvovirus B19: bioinformatical evaluation of nested PCR assays.

Variants of parvovirus B19 are currently grouped into three genotypes: 1 (reference B19 strains), 2 and 3. It has been evidenced that isolate K71 of genotype 2 is more prevalent in skin than the conventional B19 genotype 1. In this study we investigated the detection of parvovirus B19 genotypes by using two nested PCRs and evaluating the suitability of these assays by BLAST search of parvovirus isolates. Subsequently, we analyze the present genotypes in skin biopsies. The two nested PCRs employed in this study allow to amplify 41 isolates as confirmed by bioinformatical validation. The molecular epidemiological characterization of our casistics confirmed the presence of isolate K71 in human skin.

BKV-DNA and JCV-DNA Co-quantification assay to evaluate viral load in urine and serum

Infections from human polyomaviruses BK and JC (BKV and JCV) occur independently, but concomitant infections and the simultaneous persistence of both viruses have been observed in renal transplant recipients. Several studies have disclosed a correlation between BKV and interstitial nephritis in renal transplant recipients, and an association between JCV and some cases of nephropathy has recently been hypothesized. This article describes the development of a semiquantitative-nested polymerase chain reaction (PCR) assay to simultaneously detect BKV and JCV viral load in urine and serum. The first-round amplification step uses primers that amplify a 385-bp DNA fragment from the “large T antigen” region of both viruses. Samples testing positive in the first step are then run in the second step. In the second-round amplification, different inner primers are used to separately quantify BKV-DNA and/or JCV-DNA. The assay offers several advantages including: (1) rapid submission of clinical samples to screening; (2) verification of the absence of Taq polymerase inhibitors with the use of an internal control; (3) a sensitivity threshold of 10 copies/reaction; and (4) assay running is less labor intensive, cheap, and easy to perform. The assay may be easily used to monitor viral loads versus baseline levels in urine and serum samples from renal transplant recipients to detect those at risk of BKV- or JCV-related nephropathy, and to monitor their response to immunosuppression reduction therapy if it occurs.

Role of caspofungin in restoring the impaired phagocyte-dependent innate immunity towards Candida albicans in chronic haemodialysis patients

Phagocyte-dependent cellular immunity in chronic kidney disease patients undergoing haemodialysis treatment is frequently impaired owing to the uraemic state, resulting in an intrinsic susceptibility to developing invasive fungal infections with high mortality rates. Since synergism between phagocytic cells and antifungal drugs may be crucial for successful therapy, the aim of this study was to evaluate the effects exerted by caspofungin (CAS) on the functional activities of polymorphonuclear cells (PMNs) in haemodialysed patients (HDs) towards Candida albicans compared with those of PMNs from healthy subjects (HSs). PMNs were separated from venous blood samples of 66 HDs and 30 HSs (as controls), and measurement of phagocytic and intracellular fungicidal activities of HD-PMNs and HS-PMNs was performed in the presence of CAS at the minimum inhibitory concentration (MIC) and at sub-MICs. CAS-free controls were also included. In the drug-free test condition, no significant difference between the phagocytic activity of HD-PMNs and HS-PMNs was detected. In contrast, a progressive decline in the intracellular killing activity of HD-PMNs against proliferating yeasts was observed. CAS at MIC and sub-MIC levels was able to improve significantly the intracellular fungicidal activity of HD-PMNs against C. albicans, restoring their functionality. These findings provide evidence that CAS exerts a synergistic effect on HD-PMNs against C. albicans, being able to strength the depressed intracellular killing activity. These results corroborate the use of CAS as an effective therapeutic option for the treatment of invasive fungal infections in HDs, in whom even a marginal influence of antifungal drugs on host response may have a relevant effect.

Double-step PCR assay to quantify epstein-barr viral load in peripheral blood

Posttransplant lymphoproliferative disorders (PTLD) are a severe complication arising in solid organ transplant patients. A strong correlation between Epstein-Barr virus (EBV) infection, the grade and type of immunosuppression, and the development of PTLD has been recognized. This article describes the development of a double-step polymerase chain reaction (PCR) assay for the quantification of EBV-deoxyribonucleic acid (DNA) to monitor EBV infection. Screening of samples containing ≥103 viral genomes/105 peripheral blood mononuclear cells (PBMC) or 100 µL serum by a semiquantitative PCR assay is followed by quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay.Screening by semiquantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. Our double-step PCR assay can be employed in EBV viral load measurement in PBMC and serum samples to monitor transplanted patients at risk to develop PTLD.