Diversity of naturally occurring Epstein-Barr virus revealed by nucleotide sequence polymorphism in hypervariable domains in the BamHI K and N subgenomic regions.

The extent of nucleotide sequence microheterogeneity varies among subgenomic regions of Epstein-Barr virus (EBV). We examined, in EBV-carrying lymphoid cell lines, the extent of polymorphism in EBV DNA fragments amplified from the BamHI E, K, N and Z regions, and then investigated the diversity of the more hypervariable regions in tissues and body fluids. In cell lines, sequence dissimilarities in a genotype-specifying fragment of the EBNA-3C gene varied from < 1-4% within each genotype; dissimilarities in the first intron of the BZLF- 1 gene were < 2% within each genotype. By contrast, dissimilarities in a C-terminal unique domain of the EBNA-1 gene, and in a fragment that encompasses and is upstream of the LMP-1 start codon, varied between 2 and 7% and were not genotype-specific. The sequence diversity in BamHI K and N regions was then examined in tissues and body fluids by single-strand conformation polymorphism (SSCP) analysis and cycle sequencing. Extensive inter-host diversity was observed, whether the host was co-infected by human immunodeficiency virus (HIV) or not. In the oral cavity of HIV-infected patients, inter-compartmental EBV diversity could be demonstrated, even between sites that were anatomically proximate. Studies of BamHI K clones derived from EBV in oral lesions revealed infection by multiple variants. Identification of hypermutable loci within the EBV genome such as those located in the BamHI K and N regions should permit fine discrimination of individual EBV variants.

Risk factors associated with Epstein-Barr virus replication in oral epithelial cells of HIV-infected individuals.

OBJECTIVE: To examine risk factors associated with Epstein-Barr virus (EBV) replication in the oral epithelium of an HIV-infected cohort. DESIGN: Longitudinal study of behavioural, medication and immunological parameters of HIV-1-seropositive outpatients attending a genitourinary clinic. Outcome measure was EBV DNA positivity in curetted oral squames, as detected by in situ hybridization. Logistic regression for repeated observations of the same individuals was used to analyse how risk changed over time. RESULTS: Fifty six individuals were studied; 158 patient-visits were made in total (mean, 2.8). Of 137 samples curetted from the tongue, 36 were positive for EBV DNA. Recreational drug use, oral sexual practices, therapy with zidovudine and aciclovir, and changes in CD4 and total lymphocyte counts were not associated with changes in risk. Alcohol drinking, elevated CD8 lymphocyte counts and fluconazole therapy were associated with a decreased risk, and cigarette smoking with increased risk. CONCLUSION: Behavioural and HIV-specific immunological changes may play important roles in promoting and affecting the course of oral EBV replication. Rigorous anticandidal therapy and avoidance of cigarette smoking may retard the development of oral hairy leukoplakia.