Dominance of variant A in Human Herpesvirus 6 viraemia after renal transplantation

<p>Abstract</p> <p>Background</p> <p>Human herpesvirus 6 (HHV-6), mostly variant B reactivation in renal transplant patients has been published by other authors, but the pathogenetic role of HHV-6 variant A has not been clarified. Our aims were to examine the prevalence of HHV-6, to determine the variants, and to investigate the interaction between HHV-6 viraemia, human cytomegalovirus (HCMV) infection and clinical symptoms.</p> <p>Methods</p> <p>Variant-specific HHV-6 nested PCR and quantitative real-time PCR were used to examine blood samples from renal transplant patients and healthy blood donors for the presence and load of HHV-6 DNA and to determine the variants. Active HHV-6 infection was proved by RT-PCR, and active HCMV infection was diagnosed by pp65 antigenaemia test.</p> <p>Results</p> <p>HHV-6 viraemia was significantly more frequent in renal transplant patients compared to healthy blood donors (9/200 vs. 0/200; p = 0.004), while prevalence of HHV-6 latency was not significantly different (13/200 vs. 19/200; p > 0.05). Dominance of variant A was revealed in viraemias (8/9), and the frequency of HHV-6A was significantly higher in active infections compared with latency in renal transplant patients (8/9 vs. 2/13; p = 0.0015). Latency was established predominantly by HHV-6B both in renal transplant patients and in healthy blood donors (11/13 and 18/19). There was no statistical significant difference in occurrence of HCMV and HHV-6 viraemia in renal transplant patients (7/200 vs. 9/200). Statistical analysis did not reveal interaction between HHV-6 viraemia and clinical symptoms in our study.</p> <p>Conclusions</p> <p>Contrary to previous publications HHV-6A viraemia was found to be predominant in renal transplant patients. Frequency of variant A was significantly higher in cases of active infection then in latency.</p

Exhausted Cytotoxic Control of Epstein-Barr Virus in Human Lupus

Systemic Lupus Erythematosus (SLE) pathology has long been associated with an increased Epstein-Barr Virus (EBV) seropositivity, viremia and cross-reactive serum antibodies specific for both virus and self. It has therefore been postulated that EBV triggers SLE immunopathology, although the mechanism remains elusive. Here, we investigate whether frequent peaks of EBV viral load in SLE patients are a consequence of dysfunctional anti-EBV CD8+ T cell responses. Both inactive and active SLE patients (n = 76 and 42, respectively), have significantly elevated EBV viral loads (P = 0.003 and 0.002, respectively) compared to age- and sex-matched healthy controls (n = 29). Interestingly, less EBV-specific CD8+ T cells are able to secrete multiple cytokines (IFN-γ, TNF-α, IL-2 and MIP-1β) in inactive and active SLE patients compared to controls (P = 0.0003 and 0.0084, respectively). Moreover, EBV-specific CD8+ T cells are also less cytotoxic in SLE patients than in controls (CD107a expression: P = 0.0009, Granzyme B release: P = 0.0001). Importantly, cytomegalovirus (CMV)-specific responses were not found significantly altered in SLE patients. Furthermore, we demonstrate that EBV-specific CD8+ T cell impairment is a consequence of their Programmed Death 1 (PD-1) receptor up-regulation, as blocking this pathway reverses the dysfunctional phenotype. Finally, prospective monitoring of lupus patients revealed that disease flares precede EBV reactivation. In conclusion, EBV-specific CD8+ T cell responses in SLE patients are functionally impaired, but EBV reactivation appears to be an aggravating consequence rather than a cause of SLE immunopathology. We therefore propose that autoimmune B cell activation during flares drives frequent EBV reactivation, which contributes in a vicious circle to the perpetuation of immune activation in SLE patients

Utilization of Microsatellite Polymorphism for Differentiating Herpes Simplex Virus Type 1 Strains ▿ †

The herpes simplex virus type 1 (HSV-1) genome is a linear double-stranded DNA of 152 kpb. It is divided into long and short regions of unique sequences termed UL and US, respectively, and these are flanked by regions of inverted internal and terminal repeats. Microsatellites are short tandem repeats of 1- to 6-nucleotide motifs; they are often highly variable and polymorphic within the genome, which raises the question of whether they may be used as molecular markers for the precise differentiation of HSV-1 strains. In this study, 79 different microsatellites (mono-, di-, and trinucleotide repeats) in the HSV-1 complete genome were identified by in silico analysis. Among those microsatellites, 45 were found to be distributed in intergenic or noncoding inverted repeat regions, while 34 were in open reading frames. Length polymorphism analysis of the PCR products was used to investigate a set of 12 distinct HSV-1 strains and allowed the identification of 23 polymorphic and 6 monomorphic microsatellites, including two polymorphic trinucleotide repeats (CGT and GGA) within the UL46 and US4 genes, respectively. A multiplex PCR method that amplified 10 polymorphic microsatellites was then developed for the rapid and accurate genetic characterization of HSV-1 strains. Each HSV-1 strain was characterized by its own microsatellite haplotype, which proved to be stable over time in cell culture. This relevant innovative tool was successfully applied both to confirm the close relationship between sequential HSV-1 isolates collected from patients with multiple recurrent infections and to investigate putative nosocomial infections