Biology of Epstein‐Barr Virus during Infectious Mononucleosis

Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus associated with many malignant and nonmalignant human diseases. Life-long latent EBV persistence occurs in blood-borne B lymphocytes, while EBV intermittently productively replicates in mucosal epithelia. Although several models have previously been proposed, the mechanism of EBV transition between these two reservoirs of infection has not been determined. In this study, we present the first evidence demonstrating that EBV latently infects a unique subset of blood-borne mononuclear cells that are direct precursors to Langerhans cells and that EBV both latently and productively infects oral epithelium-resident cells that are likely Langerhans cells. These data form the basis of a proposed new model of EBV transition from blood to oral epithelium in which EBV-infected Langerhans cell precursors serve to transport EBV to the oral epithelium as they migrate and differentiate into oral Langerhans cells. This new model contributes fresh insight into the natural history of EBV infection and the pathogenesis of EBV-associated epithelial disease. Epstein-Barr virus (EBV) is a human herpesvirus that ultimately infects 95% of adults worldwide. EBV is transmitted via mucosal fluids and establishes life-long persistent infection.Although persistent infection is asymptomatic in most people, EBV is associated with benign syndromes, including infectious mononucleosis and oral hairy leukoplakia, and a wide variety of both lymphoid and mucosal epithelial malignancies. Persistent latent EBV infection occurs in memory B lymphocytes that circulate in blood (22). While latent EBV infection also occurs in some epithelial malignancies (29), EBV infection of epithelial cells typically results in productive replication, as demonstrated in oral hairy leukoplakia (9) and in normal oral epithelium (8,10,48).Three different models have previously been proposed to explain the transition of EBV from the latent reservoir of infection in blood-borne B lymphocytes to sites of productive replication in oral epithelium. Model 1 proposes that B lymphocytes carrying latent EBV infection migrate from the blood to the epithelium, where the EBV reactivates and infects adjacent epithelial cells (12), but evidence of intraepithelial B lymphocytes in normal oral epithelium or in oral hairy leukoplakia is lacking (30, 33). Model 2 proposes that EBV virions produced by B lymphocytes in the oral submucosa bind submucosal EBV-specific dimeric immunoglobulin A (IgA) and enter basal oral epithelial cells by endocytosis via the polymeric Ig receptor (37), but the polymeric Ig receptor is not expressed in oral epithelium (23). Model 3 proposes that EBV virions produced by B lymphocytes in oral lymphoid tissues (26) gain access to and infect middle-and upper-layer oral epithelial cells as a result of microscopic traumatic epithelial injury, such as that which occurs during mastication. However, this model is contradicted by evidence that EBV transitions into oral epithelium as cell-associated latent infecti...

Section: Cd11csupporting

confidence: 80%

Epstein-Barr Virus Infection of Langerhans Cell Precursors as a Mechanism of Oral Epithelial Entry, Persistence, and Reactivation

Walling

Ray²,

Nichols

et al. 2007

“…4) (85). In previous studies, compartmental differences in strain prevalence were detected between the oral cavity and PBL in asymptomatic carriers and infectious mononucleosis patients (83,84).…”

Section: Analysis Of the Transmembrane Domain Sequence Of Lmp1mentioning

confidence: 87%

“…After centrifugation through a cesium chloride step gradient, the DNA was dialyzed, proteinase K digested, phenol-chloroform extracted, and ethanol precipitated. The throat wash sample was purified as previously described (83).…”

Section: Methodsmentioning

confidence: 99%

Potential Selection of LMP1 Variants in Nasopharyngeal Carcinoma

Edwards

Sitki-Green

Moore

et al. 2004

Seven distinct sequence variants of the Epstein-Barr virus latent membrane protein 1 (LMP1) have been identified by distinguishing amino acid changes in the carboxy-terminal domain. In this study the transmembrane domains are shown to segregate identically with the distinct carboxy-terminal amino acid sequences. Since strains of LMP1 have been shown to differ in abundance between blood and throat washes, nasopharyngeal carcinomas (NPCs) from areas of endemicity and nonendemicity with matching blood were analyzed by using a heteroduplex tracking assay to distinguish LMP1 variants. Striking differences were found between the compartments with the Ch1 strain prevalent in the NPCs from areas of endemicity and nonendemicity and the B958 strain prevalent in the blood of the endemic samples, whereas multiple strains of LMP1 were prevalent in the blood of the nonendemic samples. The possible selection against the B958 strain appearing in the tumor was highly significant (P < 0.0001). Sequence analysis of the full-length LMP1 variants revealed changes in many of the known and computer-predicted HLA-restricted epitopes with changes in key positions in multiple, potential epitopes for the specific HLA of the patients. These amino acid substitutions at key positions in the LMP1 epitopes may result in a reduced cytotoxic-T-lymphocyte response. These data indicate that strains with specific variants of LMP1 are more likely to be found in NPC. The predominance of specific LMP1 variants in NPC could reflect differences in the biologic or molecular properties of the distinct forms of LMP1 or possible immune selection.

“…However, these assays are more qualitative than quantitative. More-recent studies have employed PCR-based analyses (heteroduplex tracking assays or cloning and Sanger sequencing) to demonstrate particular heterogeneities of LMP1 sequences (13,14).…”

Section: Importancementioning

confidence: 99%

Epstein-Barr Virus Latent Membrane Protein 1 Genetic Variability in Peripheral Blood B Cells and Oropharyngeal Fluids

Renzette

Somasundaran

Brewster

et al. 2014

We report the diversity of latent membrane protein 1 (LMP1) gene founder sequences and the level of Epstein-Barr virus (EBV) genome variability over time and across anatomic compartments by using virus genomes amplified directly from oropharyngeal wash specimens and peripheral blood B cells during acute infection and convalescence. The intrahost nucleotide variability of the founder virus was 0.02% across the region sequences, and diversity increased significantly over time in the oropharyngeal compartment (P ‫؍‬ 0.004). The LMP1 region showing the greatest level of variability in both compartments, and over time, was concentrated within the functional carboxyl-terminal activating regions 2 and 3 (CTAR2 and CTAR3). Interestingly, a deletion in a proline-rich repeat region (amino acids 274 to 289) of EBV commonly reported in EBV sequenced from cancer specimens was not observed in acute infectious mononucleosis (AIM) patients. Taken together, these data highlight the diversity in circulating EBV genomes and its potential importance in disease pathogenesis and vaccine design. IMPORTANCEThis study is among the first to leverage an improved high-throughput deep-sequencing methodology to investigate directly from patient samples the degree of diversity in Epstein-Barr virus (EBV) populations and the extent to which viral genome diversity develops over time in the infected host. Significant variability of circulating EBV latent membrane protein 1 (LMP1) gene sequences was observed between cellular and oral wash samples, and this variability increased over time in oral wash samples. The significance of EBV genetic diversity in transmission and disease pathogenesis are discussed.