The Epstein-Barr virus (EBV), traditionally linked etiologically with infectious mononucleosis (IM), endemic Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC) has in recent years been associated with a host of other conditions. Viral strategies for entry into cells and persistence, as well as various molecular mechanisms involved in latency, replication and transformation have been elucidated. EBV termini analysis has demonstrated the essentially clonal nature of BL, NPC and preneoplastic lesions of the nasopharynx. Strain variation between isolates of EBV suggests that differences in epithelial cell tropism among strains may exist. Treatment of EBV-associated syndromes is largely supportive although antivirals may play a role in the management of oral hairy leukoplakia. At the present time, the development of an effective vaccine remains a viable proposition.
Field isolates of herpesviruses recovered from falcon, pigeon, and psittacine birds were compared by restriction endonuclease (RE) analysis using four separate enzymes. Pigeon and falcon herpesviruses had strikingly similar DNA cleavage patterns, while DNA cleavage pattern of virus isolates from a double-yellow headed Amazon and an African grey parrot had different genomic patterns to both the pigeon and falcon herpesviruses. These findings support the field observations that pigeon herpesvirus causes a fatal herpesviral infection in the livers of pigeon-eating falcons.
In this study, we have sequenced the C-terminal part of the Epstein-Barr virus (EBV)-BNLF-1 gene encoding for the latent membrane protein-1 from tissues of EBV-positive Danish Hodgkin's disease (HD) and of Danish and Malaysian peripheral T-cell lymphomas (PTLs) and from tonsils of Danish infectious mononucleosis (IM). Our study showed that some of the 7 single-base mutations and the 30-bp deletion previously detected between codons of amino acid 322 and 366 in the BNLF-1 gene of the nasopharyngeal carcinoma cell line CAO were present in all Malaysian PTLs and in 60% of the Danish PTLs. In HD and the IM cases, the mutations were present in about 30%. The 30-bp deletion and the single base mutations occurred independently, and mutations were detectable in the majority of EBV type B-positive cases. These findings suggest that the 30-bp deletion and the 7 single-base mutations in the C-terminal part of the CAO-BNLF-1 gene do not characterize a new EBV type A substrain. Rather, some of the positions of single base mutations and the 30-bp deletion are hot spots that may have mutated independently through the evolution of EBV strains.