Cases of nasopharyngeal carcinoma (NPC) from North Africa show an unusual bimodal age distribution. As elsewhere, the tumor is closely associated with the presence of Epstein-Barr virus (EBV). The expression of EBV genes and c-onc genes was studied in biopsy specimens from tumors at different clinical stages from 11 young (10 to 30-year-old) and 11 adult (30 to 65-year-old) patients. It was found that the two age groups do not differ in their pattern of gene expression, that there is a tendency for later stage biopsies to express more viral and c-onc transcripts, and that samples expressing larger numbers of EBV genes also tend to express many different c-onc specificities.

In contrast with most Epstein-Barr virus (EBV)-infected healthy carriers, nasopharyngeal carcinoma patients frequently have increased serum levels of antibodies directed against EBV-DNase. These antibodies are potentially interesting serological markers for the diagnosis and the follow-up of nasopharyngeal carcinoma (NPC). In this context, it is important to determine whether malignant EBV-infected cells are the source of significant amounts of EBV-DNase contributing to antigenic stimulation. Therefore EBV-DNase expression has been investigated in several NPC specimens. A significant expression of this viral enzyme was demonstrated in both fresh biopsies and transplanted tumor lines. The DNase isolated from tumor has a molecular weight varying between 52 and 60 kDa and its activity eluted from a single-stranded DNA affinity column was specifically inhibited by both NPC sera and the rabbit polyclonal antibody against EBV-DNase. The enzyme activity was functional in the presence of 300 mM KCl, with which cellular DNases are completely inhibited. The DNase was mainly localized in epithelial tumor cells of both NPC biopsies and nude mice-derived NPC cells.

Cases of nasopharyngeal carcinoma (NPC) from North Africa show an unusual bimodal age distribution. As elsewhere, the tumor is closely associated with the presence of Epstein-Barr virus (EBV). The expression of EBV genes and c-onc genes was studied in biopsy specimens from tumors at different clinical stages from 11 young (10 to 30-year-old) and 11 adult (30 to 65-year-old) patients. It was found that the two age groups do not differ in their pattern of gene expression, that there is a tendency for later stage biopsies to express more viral and c-onc transcripts, and that samples expressing larger numbers of EBV genes also tend to express many different c-onc specificities.