Valacyclovir or valganciclovir for cytomegalovirus prophylaxis: A randomized controlled trial in adult and pediatric kidney transplant recipients.

BACKGROUND: Valganciclovir (valG), a cytomegalovirus (CMV) prophylactic agent, has dose-limiting side effects. The tolerability and effectiveness of valacyclovir (valA) as CMV prophylaxis is unknown. METHODS: We conducted a randomized, open-label, single-center trial of valA versus valG for all posttransplant CMV prophylaxis in adult and pediatric kidney recipients. Participants were randomly assigned to receive valA or valG. Primary endpoints were the incidence of CMV viremia and side-effect related drug reduction with secondary assessment of incidence of EBV viremia. RESULTS: Of the 137 sequential kidney transplant recipients enrolled, 26 % were positive and negative for CMV antibody in donor and recipient respectively. The incidence of CMV viremia (4 of 71 [6 %]; 8 of 67 [12 %] P = 0.23), time to viremia (P = 0.16) and area under CMV viral load time curve (P = 0.19) were not significantly different. ValG participants were significantly more likely to require side-effect related dose reduction (15/71 [21 %] versus 1/66 [2 %] P = 0.0003). Leukopenia was the most common reason for valG dose reduction and granulocyte-colony stimulating factor was utilized for leukopenia recovery more frequently (25 % in valG vs 5 % in valA: P = 0.0007). Incidence of EBV viremia was not significantly different. CONCLUSIONS: ValA has significantly less dose-limiting side effects than valG. In our study population, a significant increase in CMV viremia was not observed, in adults and children after kidney transplant, compared to valG. TRIAL REGISTRATION NUMBER: NCT01329185.

Cell activation-based screening of natively paired human T cell receptor repertoires.

Adoptive immune therapies based on the transfer of antigen-specific T cells have been used successfully to treat various cancers and viral infections, but improved techniques are needed to identify optimally protective human T cell receptors (TCRs). Here we present a high-throughput approach to the identification of natively paired human TCRα and TCRß (TCRα:ß) genes encoding heterodimeric TCRs that recognize specific peptide antigens bound to major histocompatibility complex molecules (pMHCs). We first captured and cloned TCRα:ß genes from individual cells, ensuring fidelity using a suppression PCR. We then screened TCRα:ß libraries expressed in an immortalized cell line using peptide-pulsed antigen-presenting cells and sequenced activated clones to identify the cognate TCRs. Our results validated an experimental pipeline that allows large-scale repertoire datasets to be annotated with functional specificity information, facilitating the discovery of therapeutically relevant TCRs.

Declining Epstein-Barr Virus Antibody Prevalence in College Freshmen Strengthens the Rationale for a Prophylactic EBV Vaccine.

BACKGROUND: To better understand the epidemiology of primary Epstein-Barr virus (EBV) infection and to identify EBV-naïve candidates eligible to receive a prophylactic EBV vaccine, we screened freshmen from the University of Minnesota Class of 2025 for circulating EBV antibody, which is indicative of previous infection. This permitted us to compare their EBV antibody prevalence with that of 4 other freshman classes (Classes of 2010, 2011, 2016, 2021) that have been previously published. METHODS: Freshman students were recruited during screening sessions in the residence halls. Venous blood was collected and the serum fraction tested for IgG antibody against EBV viral capsid antigen (VCA IgG) using commercial enzyme immunoassays. RESULTS: All classes combined, 1196 participants were tested (female, 677; male, 513; did not identify gender, 6) who were 18-23 years old (median, 18; mean, 18.37). The EBV VCA IgG antibody prevalence was 58% (689/1196) and was higher in women than men. The EBV antibody prevalence of 64% (170/267) in the 2010 freshman class versus 52% (78/150) in the Class of 2025 was statistically significantly different (p = 0.0223, Fisher exact test)." CONCLUSIONS: Sufficient participants are available for a prophylactic vaccine trial. Antibody prevalence decreased over 15 years from 64% to 52%. If this trend continues, the number of EBV-naïve adolescents and young adults who are in the age group most susceptible to infectious mononucleosis will increase, strengthening the rationale to develop an effective prophylactic EBV vaccine.

Rapid antibody responses to Epstein-Barr virus correlate with reduced severity of primary infection.

BACKGROUND: We investigated Epstein-Barr virus (EBV) antibody kinetics in university freshmen who developed laboratory-documented primary EBV infection during prospective studies and correlated these kinetics with disease severity. METHODS: EBV-naïve participants had blood collected periodically and sera tested for EBV-specific antibodies with line blot and enzyme immunoassays. The line blot assay contained EBNA-1, p18, p23, BZLF-1, p138, and p54 antigens; the enzyme immunoassay contained viral capsid antigen and EBNA-1. Severity of illness (SOI) was graded 0 (asymptomatic) to 6 (bedridden). Participants with maximum SOI scores 0-2 were compared with those whose maximum SOI scores were 3-6. Time to first antibody response was analyzed using the semi-parametric COX model. RESULTS: A total of 201 sera from 38 college students collected before, during, and after primary EBV infection were tested. Earlier antibody responses correlated with milder symptoms. This was most pronounced for late-developing antibodies. The median time to development of p18 IgG was significantly earlier among low-SOI participants (64 days) than high-SOI patients (119 days; P = 0.0003).). Participants with mild disease developed EBNA-1 antibodies sooner than participants with more severe disease (125 days versus >270 days; P = 0.017). Participants with mild disease also showed more rapid loss of antibodies against IgG EA p138 and p54 ≥12 weeks post-infection (P = 0.012 and P = 0.026, respectively). CONCLUSIONS: These data suggest that rapid antibody responses to EBV correlate with reduced severity of primary EBV infection.

Immortalization and functional screening of natively paired human T cell receptor repertoires.

Functional analyses of the T cell receptor (TCR) landscape can reveal critical information about protection from disease and molecular responses to vaccines. However, it has proven difficult to combine advanced next-generation sequencing technologies with methods to decode the peptide-major histocompatibility complex (pMHC) specificity of individual TCRs. We developed a new high-throughput approach to enable repertoire-scale functional evaluations of natively paired TCRs. In particular, we leveraged the immortalized nature of physically linked TCRα:ß amplicon libraries to analyze binding against multiple recombinant pMHCs on a repertoire scale, and to exemplify the utility of this approach, we also performed affinity-based functional mapping in conjunction with quantitative next-generation sequencing to track antigen-specific TCRs. These data successfully validated a new immortalization and screening platform to facilitate detailed molecular analyses of disease-relevant antigen interactions with human TCRs.

Development of an Improved Epstein-Barr Virus (EBV) Neutralizing Antibody Assay to Facilitate Development of a Prophylactic gp350-Subunit EBV Vaccine.

No licensed vaccine is available for prevention of EBV-associated diseases, and robust, high-throughput bioanalytical assays are needed to evaluate immunogenicity of gp350 subunit-based candidate EBV vaccines. Here we have developed an improved EBV-GFP based neutralization assay for such a vaccine's pre-clinical and clinical validation to measure EBV specific neutralizing antibodies in human donors. The supplementation of guinea pig complement of our previously published high-throughput EBV-GFP fluorescent focus (FFA)-based neutralization assay allowed the detection of complement-dependent neutralizing antibodies using a panel of heat-inactivated healthy human sera. Anti-gp350 antibody titers, which were evaluated using a previously optimized anti-gp350 IgG ELISA assay, were moderately correlated to the FFA-based neutralization titers. Overall, this improved high-throughput neutralization assay is capable of characterizing the serologic neutralizing antibody response to natural EBV infection, with applications in evaluating EBV antibody status in epidemiologic studies and immunogenicity of candidate gp350-subunit EBV vaccines in clinical studies.

The promise of a prophylactic Epstein-Barr virus vaccine.

The worldwide burden of disease due to Epstein-Barr virus (EBV) infection is enormous. Diseases include endemic Burkitt lymphoma, infectious mononucleosis, cancers after transplantation, Hodgkin lymphoma, and nasopharyngeal carcinoma. A prophylactic EBV vaccine has the potential to significantly reduce the incidence and/or the severity of all these diseases. Infectious mononucleosis can be nasty and prolonged with a median duration of 17 days. Patients, especially children, undergoing bone marrow or solid organ transplantation may develop post-transplant lymphoproliferative disorder (PTLD). Preventing or modifying primary EBV infection could reduce the incidence PTLD, and also certain lymphomas and nasopharyngeal carcinoma. EBV is a major environmental risk factor for multiple sclerosis (MS). Contracting EBV is essential to getting MS, and having a childhood case of infectious mononucleosis increases that risk. Vaccinating against EBV could be vaccinating against MS.

Primary Epstein-Barr virus infection with and without infectious mononucleosis.

BACKGROUND: Infectious mononucleosis (IM) is a common adverse presentation of primary infection with Epstein-Barr virus (EBV) in adolescence and later, but is rarely recognized in early childhood where primary EBV infection commonly occurs. It is not known what triggers IM, and also not why IM risk upon primary EBV infection (IM attack rate) seemingly varies between children and adolescents. IM symptoms may be severe and persist for a long time. IM also markedly elevates the risk of Hodgkin lymphoma and multiple sclerosis for unknown reasons. The way IM occurrence depends on age and sex is incompletely described and hard to interpret etiologically, because it depends on three quantities that are not readily observable: the prevalence of EBV-naϊve persons, the hazard rate of seroconverting and the attack rate, i.e. the fraction of primary EBV infections that is accompanied by IM. We therefore aimed to provide these quantities indirectly, to obtain epidemiologically interpretable measures of the dynamics of IM occurrence to provide etiological clues. METHODS AND FINDINGS: We used joint modeling of EBV prevalence and IM occurrence data to provide detailed sex- and age-specific EBV infection rates and IM attack rates and derivatives thereof for a target population of all Danes age 0-29 years in 2006-2011. We demonstrate for the first time that IM attack rates increase dramatically rather precisely in conjunction to typical ages of puberty onset. The shape of the seroconversion hazard rate for children and teenagers confirmed a priori expectations and underlined the importance of what happens at age 0-2 years. The cumulative risk of IM before age 30 years was 13.3% for males and 22.4% for females. IM is likely to become more common through delaying EBV infection in years to come. CONCLUSIONS: The change in attack rate at typical ages of puberty onset suggests that the immunologic response to EBV drastically changes over a relatively short age-span. We speculate that these changes are an integrated part of normal sexual maturation. Our findings may inform further etiologic research into EBV-related diseases and vaccine design. Our methodology is applicable to the epidemiological study of any infectious agent that establishes a persistent infection in the host and the sequelae thereof.

Epstein-Barr Virus DNA in Parental Oral Secretions: A Potential Source of Infection for Their Young Children.

Background: A potential source of primary Epstein-Barr virus (EBV) infection for young children is parental oral secretions. If parents who identify with racial/ethnic categories other than white have a higher prevalence of oral EBV DNA, this difference could explain why their children acquire primary EBV infection at an earlier age than white children. Methods: To test this hypothesis, we recruited parents who brought their children <8 years old to routine clinic visits, and tested the parents' oral washes for EBV DNA by real-time polymerase chain reaction. Positive samples were assayed for encapsidated EBV DNA, which is potentially infectious, versus naked EBV DNA, which is not infectious. Results: Overall, 221/800 parents (28%) had EBV DNA in their oral washes. Oral EBV DNA was more prevalent in parents who identified as non-white as compared with white parents (P = .0004), and was more prevalent in male vs female parents (P = .04). The mean quantity of EBV DNA in positive samples was 5000 copies/mL. Encapsidated viral DNA comprised 40.3% of the total EBV DNA found in parental oral secretions. Conclusions: Our data support the hypothesis that parents could be a source of virus for their young children, because 28% of parents had a mean of 5000 EBV copies/mL of oral wash and 40.3% of the EBV DNA was encapsidated. The higher prevalence of EBV DNA in non-white parents could explain why their children acquire EBV at an earlier age than children of white parents.

Primary Epstein-Barr virus infection.

Epstein-Barr virus (EBV) infects about 90% of adults worldwide. It is the main cause of infectious mononucleosis, which is observed most frequently in adolescents. The disease can last several weeks and is characterized by lymphocytosis, sore throat, lymphadenopathy, and fatigue. Exposure to oral secretions during deep kissing has been identified as the major source for primary EBV infection in adolescents. Oral secretions are also thought to be the source for younger children through intimate intact or sharing food and eating utensils, although this has not been confirmed. Unlike most acute viral illnesses such as influenza, the incubation period of symptomatic primary EBV infection is unusually long, lasting about six weeks. Diagnosis is typically made by heterophile antibody tests and/or EBV-specific antibody tests. Long-term consequences may result from acquisition of the virus, including nasopharyngeal carcinoma and lymphomas. Nevertheless, there remains a surprising dearth of knowledge regarding the establishment of an immune response to persistent EBV infection, especially during the incubation period. This lack of knowledge has impaired our ability to develop an effective prophylactic EBV vaccine, despite various attempts. Our greatest challenges in EBV research are to develop a prophylactic vaccine and devise treatment strategies for persons already infected with EBV.

Transplantation of solid organ recipients shedding Epstein-Barr virus DNA pre-transplant: A prospective study.

Epstein-Barr virus (EBV) poses a significant threat to patient and graft survival post-transplant. We hypothesized that recipients who shed EBV at transplant had less immunologic control of the virus and hence were more likely to have active EBV infection and disease post-transplant. To test this hypothesis, we conducted a 5-year prospective study in primary solid organ transplant recipients. We measured EBV DNA in oral washes and blood samples by quantitative PCR before transplant and periodically thereafter for up to 4 years. Pre-transplant samples were available from 98 subjects. EBV DNA was detected pre-transplant in 32 of 95 (34%) and 5 of 93 subjects (5%) in oral wash and blood, respectively. Recipients with and without detectable pre-transplant EBV DNA were not significantly different demographically and had no significant difference in patient and graft survival (P = .6 for both comparisons) or post-transplant EBV viremia-free survival (P = .8). There were no cases of EBV-related disease or post-transplant lymphoproliferative disorder (PTLD) in any of the patients with detectable EBV DNA pre-transplant. In conclusion, detectable EBV DNA pre-transplant was not associated with differences in patient/graft survival, post-transplant EBV viremia, or EBV-related diseases including PTLD.

Prospective studies of infectious mononucleosis in university students.

We performed an intensive prospective study designed to obtain as much data as possible on the incubation and early illness periods of primary Epstein-Barr virus (EBV) infection. Undergraduate students who lacked EBV antibody and oral EBV DNA (EBV-naive) were seen every 2 weeks during their freshman year. Clinical and behavioral data, oral washes and venous blood were obtained. EBV antibodies were quantified by enzyme immunoassay and viral loads by PCR. During a median 8 months of observation, 14/85 subjects experienced primary EBV infections (24 cases/100 person-years). The only significant risk factor for acquisition of EBV infection was deep kissing (P=0.02). Eleven subjects had infectious mononucleosis with a median duration of 21 days. Two subjects were hospitalized. Infections were initially identified in 12 subjects by finding EBV DNA in oral cells before onset of symptoms and in 2 subjects by symptom reporting. EBV DNA and viral capsid antigen (VCA) IgM and gp350 IgG antibodies were present in the blood before onset of illness. To provide a more robust evaluation of primary EBV infection in undergraduate university students, we combined data on risk factors and antibody responses from this and an earlier study that used the exact same clinical and laboratory methods. The observation that the only significant risk factor for acquisition of EBV infection was deep kissing was confirmed. Most importantly, higher amounts of gp350 antibody correlated significantly with a lower severity of infectious mononucleosis (P<0.0001), which strengthens the rationale for a gp350-based prophylactic EBV vaccine.

Epstein-Barr virus dynamics in asymptomatic immunocompetent adults: an intensive 6-month study.

Characterizing Epstein-Barr virus (EBV) dynamics in asymptomatic immunocompetent persons provides a baseline for defining quantitative thresholds associated with EBV disease. Studying latent membrane protein (LMP)-1 sequence variation over time could establish the rates of reactivation and superinfection, and also trace transmission. Twelve asymptomatic adult subjects were evaluated prospectively nine times over 6 months. EBV serum antibodies were measured by enzyme immunoassay. EBV DNA in oral and whole-blood samples was quantitated by real-time (TaqMan) PCR and analyzed for LMP-1 sequence variability. All 11 antibody positive subjects had EBV DNA detected in their oral compartment at least once during the 6-month study. The quantities ranged from 1.70 to 4.91 log10 copies EBV per ml of oral cell pellet. One subject was continuously viremic for 79 days. Overall, EBV DNA was detected in 63 (24%) of 260 samples from 11 antibody-positive subjects and in 0/27 samples from an antibody-negative subject. The quantities in positive samples ranged from 1.7 to 4.9 log10 copies EBV per ml. EBV LMP-1 gene sequence variations in subjects were constant over time regardless of the compartment sampled. Subjects 18-30 years old had EBV DNA detected more frequently than subjects >30 years old (38/108 positive samples versus 25/152; P<0.001). In conclusion, EBV DNA shedding is common in asymptomatic adults. The younger adults shed more frequently, which may reflect a shorter time from their primary EBV infection to sampling. The LMP-1 sequence analysis method employed here could be used to trace person-to-person transmission because patterns remained almost identical over time.

Kinetics of Epstein-Barr Virus (EBV) Neutralizing and Virus-Specific Antibodies after Primary Infection with EBV.

Prospective studies of antibodies to multiple Epstein-Barr virus (EBV) proteins and EBV neutralizing antibodies in the same individuals before, during, and after primary EBV infection have not been reported. We studied antibody responses to EBV in college students who acquired primary EBV infection during prospective surveillance and correlated the kinetics of antibody response with the severity of disease. Neutralizing antibodies and enzyme-linked immunosorbent assay (ELISA) antibodies to gp350, the major target of neutralizing antibody, reached peak levels at medians of 179 and 333 days after the onset of symptoms of infectious mononucleosis, respectively. No clear correlation was found between the severity of the symptoms of infectious mononucleosis and the peak levels of antibody to individual viral proteins or to neutralizing antibody. In summary, we found that titers of neutralizing antibody and antibodies to multiple EBV proteins increase over many months after primary infection with EBV.

The Incubation Period of Primary Epstein-Barr Virus Infection: Viral Dynamics and Immunologic Events.

Epstein-Barr virus (EBV) is a human herpesvirus that causes acute infectious mononucleosis and is associated with cancer and autoimmune disease. While many studies have been performed examining acute disease in adults following primary infection, little is known about the virological and immunological events during EBV's lengthy 6 week incubation period owing to the challenge of collecting samples from this stage of infection. We conducted a prospective study in college students with special emphasis on frequent screening to capture blood and oral wash samples during the incubation period. Here we describe the viral dissemination and immune response in the 6 weeks prior to onset of acute infectious mononucleosis symptoms. While virus is presumed to be present in the oral cavity from time of transmission, we did not detect viral genomes in the oral wash until one week before symptom onset, at which time viral genomes were present in high copy numbers, suggesting loss of initial viral replication control. In contrast, using a sensitive nested PCR method, we detected viral genomes at low levels in blood about 3 weeks before symptoms. However, high levels of EBV in the blood were only observed close to symptom onset-coincident with or just after increased viral detection in the oral cavity. These data imply that B cells are the major reservoir of virus in the oral cavity prior to infectious mononucleosis. The early presence of viral genomes in the blood, even at low levels, correlated with a striking decrease in the number of circulating plasmacytoid dendritic cells well before symptom onset, which remained depressed throughout convalescence. On the other hand, natural killer cells expanded only after symptom onset. Likewise, CD4+ Foxp3+ regulatory T cells decreased two fold, but only after symptom onset. We observed no substantial virus specific CD8 T cell expansion during the incubation period, although polyclonal CD8 activation was detected in concert with viral genomes increasing in the blood and oral cavity, possibly due to a systemic type I interferon response. This study provides the first description of events during the incubation period of natural EBV infection in humans and definitive data upon which to formulate theories of viral control and disease pathogenesis.

Coprevalence of Epstein-Barr Virus, Cytomegalovirus, and Herpes Simplex Virus Type-1 Antibodies Among United States Children and Factors Associated With Their Acquisition.

BACKGROUND: Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus type-1 (HSV-1) infections are common worldwide, but age-specific prevalence of primary infection varies by race or ethnicity and geographical location. Comparing demographic groups could identify factors influencing the rate of acquisition, age-specific antibody prevalence is relevant for determining when to administer prophylactic vaccines, and coprevalence suggests similar risk factors. METHODS: Stored sera collected from the cross-sectional National Health and Nutrition Examination Surveys 2003-2004 cycle were tested for EBV, CMV, and HSV-1 antibody. Demographic information was obtained through self-reported questionnaires. Statistical analysis included logistic regression and multivariate analysis adjusting for the multistage cluster design. RESULTS: Overall, 36% of children had antibody against 2 or more of the viruses. Coprevalence with EBV, CMV, and HSV-1 was higher in females, in non-Hispanic blacks, and Mexican Americans, compared with non-Hispanic whites, and in those without health insurance. Antibody prevalence was associated with (1) lower household income and education and (2) greater crowding. Nearly all children with CMV antibody or HSV-1 antibody had been infected with EBV. CONCLUSIONS: There was a disproportionately high prevalence of EBV, CMV, and HSV-1 antibody among Mexican Americans and non-Hispanic blacks, groups with a lower poverty income ratio, and those with less household education. They might benefit from receiving prophylactic herpes vaccines when fairly young. The presence of EBV, CMV, or HSV-1 antibody increases the odds of having antibody against one of the other viruses and is a ripe area for future research.

Infectious Mononucleosis.

Infectious mononucleosis is a clinical entity characterized by sore throat, cervical lymph node enlargement, fatigue, and fever most often seen in adolescents and young adults and lasting several weeks. It can be caused by a number of pathogens, but this chapter only discusses infectious mononucleosis due to primary Epstein-Barr virus (EBV) infection. EBV is a γ-herpesvirus that infects at least 90% of the population worldwide. The virus is spread by intimate oral contact among teenagers and young adults. How preadolescents acquire the virus is not known. A typical clinical picture with a positive heterophile test is usually sufficient to make the diagnosis, but heterophile antibodies are not specific and do not develop in some patients. EBV-specific antibody profiles are the best choice for staging EBV infection. In addition to causing acute illness, there can also be long-term consequences as the result of acquisition of the virus. Several EBV-related illnesses occur including certain cancers and autoimmune diseases, as well as complications of primary immunodeficiency in persons with the certain genetic mutations. A major obstacle to understanding these sequelae has been the lack of an efficient animal model for EBV infection, although progress in primate and mouse models has recently been made. Key future challenges are to develop protective vaccines and effective treatment regimens.

B cell-derived circulating granzyme B is a feature of acute infectious mononucleosis.

Granzyme B (GzmB) is a serine protease best known for inducing target cell apoptosis when released by cytotoxic T lymphocytes (CTLs) or natural killer cells with pore-forming perforin. As a result, GzmB detected in the serum of virus-infected individuals has typically been attributed to these sources. Here, we show that patients with recently diagnosed infectious mononucleosis caused by Epstein-Barr virus (EBV) have high circulating levels of GzmB that may be derived from infected B cells early in course of disease. We recently reported that human B cells from healthy donors secrete active GzmB when stimulated in vitro through B-cell receptor (BCR) ligation and interleukin (IL)-21. We found that infecting B cells with EBV greatly amplified GzmB secretion in response to the same stimuli, but the expression was terminated once the infection had become latent. Our results represent a rare instance of GzmB expression by non-CTL/natural killer cells in the context of infection with a human pathogen.

Impaired Epstein-Barr Virus-Specific Neutralizing Antibody Response during Acute Infectious Mononucleosis Is Coincident with Global B-Cell Dysfunction.

Here we present evidence for previously unappreciated B-cell immune dysregulation during acute Epstein-Barr virus (EBV)-associated infectious mononucleosis (IM). Longitudinal analyses revealed that patients with acute IM have undetectable EBV-specific neutralizing antibodies and gp350-specific B-cell responses, which were associated with a significant reduction in memory B cells and no evidence of circulating antibody-secreting cells. These observations correlate with dysregulation of tumor necrosis factor family members BAFF and APRIL and increased expression of FAS on circulating B cells.