Confirmation of the low clinical effect of human herpesvirus-6 and -7 infections after renal transplantation.

Human herpesvirus-6 and -7 (HHV-6 and HHV-7) may lead to pathological manifestations in renal transplant recipients. The aim of this study was to investigate beta-herpesvirus infections in 50 adult kidney transplant recipients after transplantation to examine the effect, interactions, and pathogenic consequences of infection and the effect of immunosuppressive regimens and Human cytomegalovirus (HCMV) prophylaxis with VACV. Beta-herpesviruses loads in the blood of 50 adult kidney transplant recipients over a 6-month period after transplantation and 198 blood donors were determined using polymerase chain reaction. The rate of HHV-6 detection in peripheral mononuclear cells (PBMCs) was higher in patients with end-stage renal disease and during the post-transplantation follow-up than in healthy subjects (33% and 68% vs. 12%, respectively). The detection rate of HHV-7 in PBMCs was similar between patients, both before grafting and during the follow-up for transplant recipients (69% and 88%, respectively), and healthy subjects (78%), and correlated with the number of lymphocytes. HCMV in plasma was detected only in patients during the post-transplant period (24%). VACV prophylaxis had no negative effect on the replication of HHV-6 or HHV-7, and univariate analyses demonstrated associations between HHV-6 infection and acute graft rejection [Odds ratio (OR) = 2.94, 95% confidence interval (CI), 1.05-8.2, P = 0.04], and between HHV-7 infection and cholestasis [OR = 2.61 (95% CI, 1.08-6.3), P = 0.03]. Immunosuppressive regimens had no effect on beta-herpesviruses infections. This study revealed the differing behavior of HCMV, HHV-6, and HHV-7 in kidney transplant recipients, and confirmed the association of HHV-6 with graft rejection.

Trichloroethylene exposure and somatic mutations of the VHL gene in patients with Renal Cell Carcinoma.

BACKGROUND: We investigated the association between exposure to trichloroethylene (TCE) and mutations in the von Hippel-Lindau (VHL) gene and the subsequent risk for renal cell carcinoma (RCC). METHODS: Cases were recruited from a case-control study previously carried out in France that suggested an association between exposures to high levels of TCE and increased risk of RCC. From 87 cases of RCC recruited for the epidemiological study, 69 were included in the present study. All samples were evaluated by a pathologist in order to identify the histological subtype and then be able to focus on clear cell RCC. The majority of the tumour samples were fixed either in formalin or Bouin's solutions. The majority of the tumours were of the clear cell RCC subtype (48 including 2 cystic RCC). Mutation screening of the 3 VHL coding exons was carried out. A descriptive analysis was performed to compare exposed and non exposed cases of clear cell RCC in terms of prevalence of mutations in both groups. RESULTS: In the 48 cases of RCC, four VHL mutations were detected: within exon 1 (c.332G>A, p.Ser111Asn), at the exon 2 splice site (c.463+1G>C and c.463+2T>C) and within exon 3 (c.506T>C, p.Leu169Pro).No difference was observed regarding the frequency of mutations in exposed versus unexposed groups: among the clear cell RCC, 25 had been exposed to TCE and 23 had no history of occupational exposure to TCE. Two patients with a mutation were identified in each group. CONCLUSION: This study does not confirm the association between the number and type of VHL gene mutations and exposure to TCE previously described.

Identification of human herpesvirus 6 variants A and B by primer-specific real-time PCR may help to revisit their respective role in pathology.

BACKGROUND: Human herpesvirus 6 (HHV-6) isolates are classified into two variants, termed HHV-6A and HHV-6B, on the basis of distinct genetic, antigenic and biological characteristics, but the specific pathogenicity of each variant remains poorly understood. OBJECTIVES: To design a rapid, sensitive and specific real-time variant-specific PCR (VS-PCR) method to differentiate both variants in biological specimens. STUDY DESIGN: The VS-PCR was adapted from a real-time PCR assay, based on TaqMan technology, previously developed for the genome quantitation of both HHV-6 variants [Gautheret-Dejean A, Manichanh C, Thien-Ah-Koon F, Fillet AM, Mangeney N, Vidaud M, et al. Development of a real-time polymerase chain reaction assay for the diagnosis of human herpesvirus-6 infection and application to bone marrow transplant patients. J Virol Meth 2002;100:27-35], a consensual reverse primer (Taq2) being changed into two variant-specific primers named H6A and H6B. This method was applied to a large set of biological specimens obtained in different pathological contexts. RESULTS: The sensitivity threshold was about 10 copies/well for HHV-6A-specific PCR (PCR-A) and 1 copy/well for HHV-6B-specific PCR (PCR-B). Both assays showed a linear dynamic range from 10 to 100,000 copies of HHV-6 DNA. Regarding the specificity and the capacity of discrimination of each assay, one variant could be detected and identified in the presence of more than 1000 times higher concentrations of the other variant in virus mixtures. The comparison of the results obtained with this VS-PCR with those previously obtained with a classic PCR method allowed us to validate our new technique on a wide panel of biological samples, including numerous patients with severe HHV-6-related symptoms. The high prevalence of HHV-6B was confirmed in healthy individuals and immunocompromised patients. HHV-6A was identified in distinct samples from several patients exhibiting neurological disorders. CONCLUSIONS: We developed a new VS-PCR assay, able to differentiate HHV-6A and HHV-6B in biological samples, even in the case of mixed infections. Our study confirms the wide prevalence of HHV-6B and highlights the potential greater neuropathogenic role of HHV-6A in immunocompromised patients and young infants.

Persistence of DNA in cell cultures may jeopardize the analysis of human herpesvirus 6 dynamics by means of real-time PCR.

The use of real-time PCR has been described previously for analysing both the replication kinetics and antiviral susceptibility of human herpesvirus 6 in MT4 cells. It is now reported that viral DNA persists in infected cell culture long after the end of lytic virus replication. Consequently, high levels of DNA may correspond to an absence of infectivity and late readout occurring after the exponential phase of virus growth may lead to misinterpretation of the results of susceptibility assays. These limitations must be borne in mind when using real-time PCR.