In seropositive individuals Epstein-Barr virus (EBV) establishes a virus reservoir in peripheral blood lymphocytes (PBLs). Transmission from one individual to another occurs via saliva due to a lytic (virion productive) phase of infection in the oropharynx. EBNA-1 is responsible for maintaining viral episomes in the host cell and could, therefore, also affect the persistence of the virus in different cell lineages. Based on sequence analysis of EBNA-1 we now demonstrate that (i) in addition to the prototype EBNA-1 (identical to the B95.8 virus EBNA-1), EBV in normal individuals encompasses multiple EBNA-1 subtypes, both in PBLs and in oral

Primary effusion lymphoma (PEL) selectively involves the serous body cavities, occurs predominantly in immunodeficient patients and is infected consistently by human herpesvirus type-8. PEL is also frequently infected by EpsteinBarr virus (EBV). The precise pathogenetic role of EBV coinfection in PEL is not fully understood. The lymphoma fails to express the EBV transforming proteins EBNA-2 and LMP-1, whereas it expresses EBNA-1 (latency I phenotype). Some studies have hypothesized that other EBV-positive lymphomas expressing the latency I phenotype may associate with specific molecular variants of EBNA-1, although this issue has not been addressed in PEL. On this basis, this study is aimed at a detailed molecular characterization of EBV in PEL. Leukemia (2000) 14, 271-277.

We have previously shown that the endemic (African) and sporadic (North American) forms of Burkitt's lymphoma (BL) differ at a molecular level. We have now extended our studies to the molecular epidemiology of BL in South America, specifically to two climatic regions: temperate (Argentina and Chile) and tropical (Brazil). We have examined the patterns of chromosomal breakpoint locations in 39 tumors with respect to geography and Epstein-Barr virus (EBV) association. The result of these analyses provide further support for the existence of pathogenetically distinct subtypes of BL in different world regions. The majority of breakpoints on chromosome 8 in South American BL (41%) occurred in the immediate flanking region of c-myc, ie, further 5′ of the “typical” sporadic breakpoints, in the first exon/intron region, and further 3′ of the “typical” endemic breakpoints, which are usually distant from c-myc. However, the distribution of breakpoints on chromosome 14 in tumors from the temperate and tropical regions of South America is similar to that observed in sporadic and endemic tumors. Interestingly, only one tumor with an unrearranged c-myc gene joined to the S mu region of chromosome 14 was observed. This combination was also rarely observed in our earlier series and presumably is either less readily generated by the mechanism that mediates 8;14 translocation or requires other, infrequent genetic changes to provide the necessary selective advantage for lymphomagenesis. The frequency of EBV association in South American BL (51%) is also intermediate with respect to tumors from the United States (30%) and Africa (100%). No correlation with the breakpoint location on chromosome 8 was discernable. Surprisingly, only 54% of tumors with breakpoint outside c-myc were EBV positive. This is in contrast to endemic tumors and suggests that any pathogenetic contribution of EBV is not dependent on breakpoint location, but is more likely to complement additional pathogenetic elements that differ in different world regions.