EBV Conference 2008 Guangzhou - Baylor College of Medicine

111 (RegID: 1774)
Alan Chiang
Institution: The University of Hong Kong
e-mail: chiangak@hkucc.hku.hk
DISCORDANT EPSTEIN-BARR VIRUS (EBV) STRAINS IN PLASMA, PERIPHERAL BLOOD
MONONUCLEAR CELLS AND SALIVA OF CHILDREN WITH PRIMARY EBV INFECTION
H Kwok, KW Chan, AKS Chiang, Department of Paediatrics and Adolescent Medicine, Li Ka Shing
Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong, China
Posterabstract:
Aim: Long term virus carriers harbor multiple Epstein-Barr virus (EBV) strains. How these strains are
acquired during primary infection and how they distribute within the body compartments are not known.
We ask (1) whether multiple EBV strains are acquired during primary infection, (2) whether these strains
persist over time, and (3) how these strains distribute between B cell and epithelial cell pools.
Methods: Blood and saliva were collected from twenty Chinese children confirmed to have primary EBV
infection serologically (twelve children had infectious mononucleosis and eight children had
asymptomatic infection) at different time points from the time of diagnosis to one year post-infection.
EBV strains contained in peripheral blood mononuclear cells (PBMC), plasma and saliva were
characterized by a panel of fluorescent PCR assays on two polymorphic latent genes, EBNA2 and LMP1.
Real-time PCR typing assay classified EBV strains into types 1 and 2 based on type-specific
polymorphisms at the EBNA2 locus. LMP1 typing assay identified EBV strains with or without 30-bp
deletion at the LMP1 locus. Fluorescent heteroduplex tracking assays (HTA) distinguished five EBNA2
subtypes (group 1, 2, 3a, 3b and 3e) and seven LMP1 strains (China 1, China 2, Med+, Med-, NC, Alaska
and B95-8).
Results: No significant difference in EBV strain distribution was observed between infectious
mononucleosis and asymptomatic infections. Type 1 virus was the dominant virus (found in 19 of 20
cases), mostly as single type infections (14 of 20 cases). EBNA2 groups 1 and 3e were predominant in
PBMC and saliva whereas groups 1, 2, 3b and 3e were all found in plasma, often as multiple strains in the
same timepoint. Co-infection of LMP1 deleted and non-deleted strains were detected in 75% (15 of 20) of
cases whilst deleted strains only were found in the remaining 25% (5 of 20). LMP1 strains, China 1,
China 2 and Med+, were the predominant strains which were frequently detected as multiple strains in
PBMC, plasma and saliva in the same timepoint. Similar viral strains were found in PBMC and saliva
but different or additional strains were often detected in plasma of the same patient in the same timepoint.
Conclusion: Multiple EBV strains are already acquired during primary infection and that these strains can
persist over time. Different viral strains can be detected in PBMC, plasma and saliva at different
timepoints. Concordance of viral strains in PBMC and saliva at the same timepoint is frequently observed.
In contrast, partial or complete discordance of viral strains in plasma from those in PBMC and saliva is
often detected, indicating that plasma likely contains viral strains released from multiple sources,
including peripheral blood and epithelial cell pools as well as other cell compartments such as the
lymphoepithelial and secondary lymphoid tissues.
EBV Conference 2008 Guangzhou
- 173 -