High prevalence of Epstein–Barr virus type A strain with the 30 b.p. deletion of the latent membrane protein-1 gene in a Japanese population

BACKGROUND: The pathogenic activity of Epstein-Barr virus (EBV) with a characteristic 30 b.p. deletion of the latent membrane protein-1 (LMP-1) gene is controversial. We analyzed the LMP-1 gene and two major strains of EBV, type A and type B, in Japanese patients with EBV-associated disease. METHODS: We directly sequenced the carboxy terminal part of the LMP-1 gene from 15 EBV-infected patients; 10 patients with infectious mononucleosis (IM) and one patient each with Hodgkin's disease, B cell lymphoma, Wiskott-Aldrich syndrome (WAS), AIDS and atypical EBV infection (atEBV). The EBV subtype was studied by determining the 3' divergence of Epstein-Barr virus nuclear antigen (EBNA)-2 using polymerase chain reaction primers. RESULTS: Twelve of 15 patients had EBV with the 30 b.p. deletion and numerous point mutations of the LMP-1 gene, regardless of the disease. Two patients, one with IM and one with WAS, had EBV without the 30 b.p. deletion. One patient with atEBV had two types of LMP-1 gene, one with and one without the 30 b.p. deletion. Thirteen patients had EBV type A, the WAS patient had the type B strain and the atEBV patient had both types A and B. In the patient with atEBV, the two types of LMP-1 gene and two EBV subtypes were detected simultaneously. CONCLUSIONS: The characteristic 30 b.p. deletion of the LMP-1 gene is not an important factor in the pathogenesis of EBV-associated diseases. The EBV type A strain with the 30 b.p. deletion of the LMP-1 gene is prevalent in the Japanese population.