Kerstin I. Falk

Primary Infection with the Epstein-Barr Virus and Risk of Multiple Sclerosis

To determine whether multiple sclerosis (MS) risk increases following primary infection with the Epstein‐Barr virus (EBV), we conducted a nested case‐control study including 305 individuals who developed MS and 610 matched controls selected among the >8 million active‐duty military personnel whose serum has been stored in the Department of Defense Serum Repository. Time of EBV infection was determined by measuring antibody titers in serial serum samples collected before MS onset among cases, and on matched dates among controls. Ten (3.3%) cases and 32 (5.2%) controls were initially EBV negative. All of the 10 EBV‐negative cases became EBV positive before MS onset; in contrast, only 35.7% (n = 10) of the 28 controls with follow‐up samples seroconverted (exact p value = 0.0008). We conclude that MS risk is extremely low among individuals not infected with EBV, but it increases sharply in the same individuals following EBV infection. ANN NEUROL 2010;67:824–830

Loss of IL-7Ralpha is associated with CD4 T-cell depletion, high interleukin-7 levels and CD28 down-regulation in HIV infected patients

Objective:Elevated levels of interleukin (IL)-7 are present in the blood of HIV-positive patients and it is known that IL-7 receptor (IL-7R)α expression decreases on T cells during HIV infection. The subset(s) of T cells with low IL-7Rα and the consequence of low IL-7Rα expression for T-cell survival are poorly characterized. Design:The frequency of IL-7Rα-negative T cells in HIV-positive patients was studied in relation to CD4 T-cell counts, IL-7 concentration and survival in culture. We analysed IL-7Rα expression in different T-cell populations and in relation to Bcl-2 expression. Methods:Specimens from 38 HIV-1 patients and 17 controls were examined. IL-7Rα and Bcl-2 expression in different T-cell populations was studied by flow cytometry. The influence of IL-7Rα expression on T-cell survival was studied by culturing T cells in the presence of IL-7. Results:Down-regulation of IL-7Rα on T cells correlated with depletion of CD4 T cells (P < 0.001) and also with increased concentration of serum IL-7 (P < 0.05). The decreased IL-7Rα expression was associated with low Bcl-2 expression and with the reduced survival capacity of T cells in the presence of IL-7 in vitro. Particularly, T cells with memory phenotype showed a decreased IL-7Rα expression in association with CD28 down-regulation. Conclusions:The positive effects of IL-7 on survival and homeostatic proliferation of T cells might be severely impaired in HIV-infected individuals due to IL-7Rα down-regulation. Differentiation towards a CD28-negative memory phenotype in response to chronic activation may lead to an overall decrease of IL-7 mediated survival within the peripheral T-cell pool.

A Molecular Link between Malaria and Epstein–Barr Virus Reactivation

Although malaria and Epstein–Barr (EBV) infection are recognized cofactors in the genesis of endemic Burkitt lymphoma (BL), their relative contribution is not understood. BL, the most common paediatric cancer in equatorial Africa, is a high-grade B cell lymphoma characterized by c-myc translocation. EBV is a ubiquitous B lymphotropic virus that persists in a latent state after primary infection, and in Africa, most children have sero-converted by 3 y of age. Malaria infection profoundly affects the B cell compartment, inducing polyclonal activation and hyper-gammaglobulinemia. We recently identified the cystein-rich inter-domain region 1α (CIDR1α) of the Plasmodium falciparum membrane protein 1 as a polyclonal B cell activator that preferentially activates the memory compartment, where EBV is known to persist. Here, we have addressed the mechanisms of interaction between CIDR1α and EBV in the context of B cells. We show that CIDR1α binds to the EBV-positive B cell line Akata and increases the number of cells switching to the viral lytic cycle as measured by green fluorescent protein (GFP) expression driven by a lytic promoter. The virus production in CIDR1α-exposed cultures was directly proportional to the number of GFP-positive Akata cells (lytic EBV) and to the increased expression of the EBV lytic promoter BZLF1. Furthermore, CIDR1α stimulated the production of EBV in peripheral blood mononuclear cells derived from healthy donors and children with BL. Our results suggest that P. falciparum antigens such as CIDR1α can directly induce EBV reactivation during malaria infection that may increase the risk of BL development for children living in malaria-endemic areas. To our knowledge, this is the first report to show that a microbial protein can drive a latently infected B cell into EBV replication.

Anti-Epstein–Barr virus antibodies as serological markers of multiple sclerosis: a prospective study among United States military personnel

Background: Elevated Epstein–Barr virus (EBV) antibody titers are risk factors for multiple sclerosis (MS), but the strength and consistency of this association are not well characterized. Objectives: The objectives of this study were to determine whether this association is confounded by vitamin D or modified by gender or race, and the usefulness of EBV nuclear antigen (EBNA) antibodies as a marker for MS. Methods: We conducted a prospective study among US military personnel. Antibody titers against EBV antigens were measured in serum samples from 222 individuals who developed MS and 444 age, sex, and race/ethnicity matched controls. Conditional logistic regression was used to estimate relative risks. Results: MS risk increased with increasing titers of anti-EBNA complex (p < 10−9) and anti-EBNA-1 (p = 5.8 × 10−9) titers. MS risk was 36-fold higher among individuals with anti-EBNA complex IgG titers ≥320 than among those with titers <20 (95% confidence interval [CI] 9.6–136), and 8-fold higher among those with anti-EBNA-1 ≥320 than among those with anti-EBNA-1 <20 (95% CI 2.6–23). These associations were consistent across gender and race/ethnicity groups and independent from 25-hydroxyvitamin D levels. Areas under the receiver operating characteristic (ROC) curves were 0.67 for EBNA complex and 0.65 for EBNA-1. Conclusions: Serum titers of pre-onset anti-EBNA antibodies are strong, robust markers of MS risk and could be useful in an MS risk score.

Migrating Birds and Tickborne Encephalitis Virus

During spring and autumn 2001, we screened 13,260 migrating birds at Ottenby Bird Observatory, Sweden, and found 3.4% were infested with ticks. Four birds, each a different passerine species, carried tickborne encephalitis virus (TBEV)–infected ticks (Ixodes ricinus). Migrating birds may play a role in the geographic dispersal of TBEV-infected ticks.

Puumala Hantavirus Excretion Kinetics in Bank Voles (Myodes glareolus)

One-sentence summary for table of contents: Virus may be transmitted by saliva, urine, and feces, and saliva may play a role in transmission to humans.

Post-transplant lymphoproliferative disease and other Epstein-Barr virus diseases in allogeneic haematopoietic stem cell transplantation after introduction of monitoring of viral load by polymerase chain reaction

The clinical value of monitoring of Epstein-Barr virus (EBV) viraemia by quantitative polymerase chain reaction during 1 y was evaluated. 39 recipients of allogeneic hematopoietic stem cell transplantation (SCT) were followed. More than 100 EBV genome equivalents (gEq)/ml in blood or plasma were found in 16/39 patients (41%) at 34 d (range 1–139) post-transplant. Seven of these 16 patients developed EBV disease; 3 post-transplant lymphoproliferative disease (PTLD), 1 myelitis, 1 encephalitis and 2 reactivations with fever. EBV diseases were only found in the high-risk group among recipients of mismatched related or unrelated donor grafts or in patients who underwent reduced-intensity conditioning. In this group, 3/20 (15%) developed PTLD. Conditioning with antithymocyte globulin was significantly associated with EBV disease (p<0.01). EBV load in plasma was more strongly associated with EBV disease than viral load in blood. A cut-off level of 1000 gEq/ml plasma distinguished EBV disease from asymptomatic viraemia, but not PTLD from other EBV diseases. Weekly monitoring of EBV load in plasma in high-risk patients in the first 3 months following SCT seems to be of value for prediction of EBV disease. Therapy for PTLD including rituximab was evaluated during 2 y and showed response in 4/6 cases.

Detection of Epstein-Barr virus, but not human herpesvirus 8, DNA in cervical secretions from Swedish women by real-time polymerase chain reaction.

Background Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV-8) are two related herpesviruses that may be sexually transmitted. Goal To examine the presence of HHV-8 and EBV DNA in the female genital tract. Study Design Real-time polymerase chain reaction systems for quantification of DNA from HHV-8, EBV, and herpes simplex virus type 2 were developed and used for examination of cervical secretions from 112 Swedish women. HHV-8, EBV, and herpes simplex virus type 2 serology was also performed on samples from all subjects. Results EBV DNA was found in 10 cervical secretion samples, sometimes in high amounts. No cervical secretion or leukocyte sample contained detectable HHV-8 DNA. Antibodies to HHV-8-latent and -lytic antigens were found in 2.7% and 24% of serum samples, respectively. Conclusion This study supports a possible sexual route of transmission for EBV but not for HHV-8. The new real-time polymerase chain reaction systems could be valuable in future studies of relations between virus load and disease.

Epstein-Barr virus DNA load in cerebrospinal fluid and plasma of patients with AIDS-related lymphoma

Detection of Epstein-Barr virus (EBV) DNA in the cerebrospinal fluid (CSF) is associated with acquired immunodeficiency syndrome (AIDS)-related brain lymphoma. Real-time polymerase chain reaction (PCR) was performed to quantify EBV DNA in CSF and plasma from 42 patients with AIDS-related non-Hodgkin’s lymphoma (NHL). Twenty patients had primary central nervous system lymphoma (PCNSL) and 22 systemic NHL, including 12 with central nervous system involvement (CNS-NHL). As controls, 16 HIV-infected patients with other CNS disorders were examined. EBV DNA was detected in the CSF from 16/20 (80%) patients with PCNSL, 7/22 (32%) with systemic NHL, 8/12 (67%) with CNS-NHL, and 2/16 (13%) of the controls. The viral EBV DNA levels were significantly higher in the CSF from patients with PCNSL or CNS-NHL compared to patients with systemic NHL or controls. EBV DNA was detected in plasma from 5/16 (31%) patients with PCNSL, 9/16 (56%) with systemic NHL, 4/9 (44%) with CNS-NHL, and 4/15 (27%) controls. No difference in plasma viral load was found between patient groups. From the patients with CNS-NHL, plasma samples drawn prior to CNS involvement contained significantly higher EBV DNA levels than those from systemic NHL patients without subsequent CNS involvement. EBV DNA levels in the CSF, but not in plasma, from patients treated with antiherpes drugs were significantly lower than in untreated patients. High CSF EBV DNA levels were found in HIV-associated brain lymphomas and the viral load can be clinically useful. High plasma EBV DNA levels might predict CNS involvement in systemic NHL.

Clearance of Circulating Epstein-Barr Virus DNA in Children with Acute Malaria after Antimalaria Treatment

Children living in malaria-endemic regions have a high incidence of Burkitt lymphoma (BL), the etiology of which involves Plasmodium falciparum malaria and Epstein-Barr virus (EBV) infections. In the present study, we compared EBV DNA loads in plasma and saliva samples from Ugandan children with acute malaria (M+) at the time of diagnosis and 14 days after antimalaria treatment, children without malaria (M-), and children with BL. EBV DNA was detected, by real-time polymerase chain reaction, in 31% of the plasma and in 79% of the saliva samples from children in the M+ group. Antimalaria treatment led to clearance of plasma viral load in 85% of the cases but did not affect the levels in saliva. There was a significant difference in plasma EBV loads across the groups. The lowest levels were detected in samples from the M- group, increased levels were detected in samples from the M+ group, and levels reached the highest values in samples from children with BL. The same trend was evident in the frequency and levels of anti-BZLF1 antibodies, which is indicative of viral reactivation. In the M+ group, the positive plasma samples clustered around 7-9 years of age, the peak incidence of BL. The clearance of circulating EBV after antimalaria treatment suggests a direct relationship between active malaria infection and viral reactivation.