Epstein-Barr Virus Strains With Latent Membrane Protein-1 Deletions: Prevalence in the Italian Population and High Association With Human Immunodeficiency Virus–Related Hodgkin's Disease

Abstract

Six Epstein-Barr virus (EBV)-related lymphoproliferative disorders were investigated to verify whether the EBV strain harbored by neoplastic cells had the same EBNA-2 and latent membrane protein-1 (LMP-1) DNA sequences of the virus carried by normal lymphocytes of the same patients. Within each case, the analysis of neoplastic lymph nodes, reactive lymphadenopathies, and/or EBV+ spontaneous lymphoblastoid cell lines gave concordant results with respect to type-specific EBNA-2 region and LMP-1 gene. In particular, five cases showed the same deletion in the 3′ end of the LMP-1 gene in both normal and neoplastic cells. We also determined the prevalence of LMP-1 deletions in a large series of normal peripheral blood mononucleated cells (PBMCs) from Italian individuals. The analysis showed that 50% (9 of 18) of PBMCs from human immunodeficiency virus (HIV)-seronegative donors carried a 30-bp deletion in the C-terminal portion of the LMP-1 gene, whereas a nondeleted fragment was amplified in about 44% (8 of 18) of the cases. Only one sample (5.6%) showed the amplification of a full-length LMP-1 band together with a deleted fragment. Similarly, PBMCs from HIV-infected patients showed an almost equivalent prevalence of full-length (17 of 37, 46%) and deleted (16 of 37, 43.2%) LMP-1 fragments, whereas about 11% of samples (4 of 37) showed evidence of double infections. Of note, deletions in the LMP-1 gene were detected with similar prevalence values in EBV+ Hodgkin's disease (HD) (13 of 30, 43.3%) and non-Hodgkin's lymphoma (NHL) (2 of 5, 40%) cases from HIV-seronegative patients and in HIV-related, EBV+ NHLs (4 of 7, 57.1%). Conversely, a 30-bp LMP-1 deletion was found in 10 of 12 HIV-associated HD cases (83%), a prevalence significantly higher than that detected in HIV-unrelated HD (P = .01). These findings indicate that: (1) the same EBV strain carrying LMP-1 deletions is harbored by normal and neoplastic cells of patients with EBV+ disorders, ruling out that these mutations might result from immunoselection phenomena; (2) in the Italian population, the prevalence of LMP-1 deletion mutants is comparable to that of EBV strains with full-length LMP-1; (3) HIV-induced immunosuppression is not associated with an increased prevalence of LMP-1 deletions in PBMCs; and (4) HIV-related HD cases, but not those of HIV-seronegative Italian patients, are closely correlated with the presence of LMP-1 deletions, suggesting that infection with these strains may increase the risk of developing HD in the HIV setting.