Time course and frequency of Epstein-Barr virus reactivation after kidney transplantation: linkage to renal allograft rejection.

The onset and frequency of Epstein-Barr virus (EBV) reactivation after kidney transplantation are unknown. By use of quantitative real-time polymerase chain reaction measurements, evidence of early EBV reactivation, occurring within the first week after the initiation of immunosuppressive therapy (median, 3 days), was observed in 13 of 23 patients, of whom 10 subsequently developed rejection episodes after 2-45 days (median, 5 days). By contrast, rejection was only diagnosed in 1 of 10 patients who did not show signs of viral reactivation. We suggest that EBV reactivation may induce a T cell response that, through the phenomenon of allo-cross-reactivity, could play a critical role in graft rejection.

Molecular parameters for precise diagnosis of asymptomatic Epstein-Barr virus reactivation in healthy carriers.

Asymptomatic Epstein-Barr virus (EBV) reactivations periodically occur in oral mucosa-associated lymphoid tissues. Until now, EBV reactivation has been diagnosed by serologic profiles that suggest virus replication. Serologic responses, however, are delayed and do not necessarily indicate ongoing replicative activity. The aim of the present study was to establish in healthy carriers parameters for a molecular diagnosis of reactivated EBV infection. Recent studies emphasized the association of an increase in peripheral-B-cell viral load with replicative activity at remote sites. Therefore, real-time PCR was used to quantitate EBV genomes in the peripheral blood mononuclear cells (PBMC) (viral load) and plasma samples (viremia) of 22 healthy EBV-seropositive blood donors over a period of 15 months. Furthermore, transcription of the immediate-early gene encoding BZLF1 was investigated in the PBMC of all volunteers. Serology suggested reactivation in nine donors, of whom all but one showed at least once a significant increase in viral load. Another five individuals also exhibited significant changes in viral load but no serologic response. Of the 13 volunteers with significant increases in viral load, 6 had a period of viremia accompanying the rise in viral load. A stable viral load without viremia and negative serology was seen in eight adults. BZLF1 mRNA was undetectable throughout. We conclude that for healthy subjects serology underestimates the frequency of asymptomatic EBV reactivations. Prospective examination of peripheral viral load and viremia is suitable for the exact diagnosis of EBV reactivation, which might be of advantage for immunocompromised patients in whom EBV reactivations are considerably harmful.

Inhibition of macrophage inflammatory protein-1 alpha production by Epstein-Barr virus.

Infection with Epstein-Barr virus (EBV) exerts substantially immunomodulating activities in vitro and in vivo. In this context, EBV-induced chemokine production and the influence of EBV on this highly redundant system of inflammatory proteins have hardly been investigated. This study analyzed the production of interleukin-8, RANTES, monocyte chemotactic protein-1, and macrophage inflammatory protein-1 alpha (MIP-1 alpha) on EBV infection of peripheral blood mononuclear cells from immune EBV-seropositive (EBV(+)) and noninfected EBV-seronegative (EBV(-)) individuals. EBV failed to induce the production of MIP-1 alpha in EBV(+) as well as EBV(-) individuals, whereas the other chemokines studied were readily expressed. Moreover, EBV completely down-regulated lipopolysaccharide (LPS)- and phytohemagglutinin-induced MIP-1 alpha production up to 4 hours after induction. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of EBV- and LPS-stimulated cultures revealed that EBV inhibited MIP-1 alpha production on the transcriptional level. This effect was abolished by addition of antiglycoprotein (gp)350/220, a monoclonal antibody against EBV's major envelope glycoprotein, which mediates binding of the virus to the EBV receptor, CD21. However, recombinant gp350/220 protein alone did not inhibit the LPS-induced MIP-1 alpha production, indicating that infection of the target cell is indispensable for this effect. In summary, we demonstrate a new immunomodulating activity of EBV on the chemokine system that probably helps the virus to evade the host's immune system favoring lifelong infection.