The prevalent strain of Epstein-Barr virus (EBV) in EBVrelated malignancies and in healthy adults in Southern Japan was examined by means of polymerase chain reaction (PCR) and/or restriction fragment length polymorphism (RFLP) analysis. In EBV-related gastric cancers, 51/73 cases were subtype A, 4 were subtype B and the EBNA-2 region was not amplified in 18 cases. Sixty-three were wild-type F, and only one was variant ''f''. Sixty-one cases had type C and 2 type D. EBNA-2 subtype A was found in 10/12 EBV-related T/NK-cell lymphomas, and 11 samples harbored the wild-type F. Neither subtype B nor the ''f'' variant was detected. The Epstein-Barr virus (EBV) is a B-lymphotropic human herpesvirus that is acquired during early childhood (after 3 months of age) and persists for the rest of life, with intermittent shedding from mucosal surfaces (Huang et al., 1993). EBV causes infectious mononucleosis (IM) after primary infection in young adults and is closely associated with the pathogenesis of Burkitt's lymphoma (BL) in equatorial Africa, nasopharygeal carcinoma (NPC) in Southeast Asia and other malignancies (Liebowitz and Kieff, 1993).There are 2 subtypes of EBV, A and B, that differ in their capacity to transform B lymphocytes into a state of continuous proliferation (immortalization) (Liebowitz and Kieff, 1993). Subtype A virus is predominant in developed societies, and subtype B is found in 40% of BL cases and 20% of healthy adults in Africa (Zimber et al., 1986;Young et al., 1987). However, Sixbey et al. (1989) identified subtype B in 40% of healthy individuals in the United States. Restriction fragment length polymorphism (RFLP) analysis distinguishes between wild-type F and the ''f '' variant in the Bam HI F region, and between type C and D in the Bam HI I region. The ''f'' variant, having an extra Bam HI restriction site in the Bam HI F region, is considered to be associated with development and/or maintenance of NPC in Southern China, because it is found in nearly 60% of NPC patients and 19% of healthy adults in that region (Lung et al., 1988;. The type C virus lacks a Bam HI restriction site in the Bam HI I region and is prevalent in Southern China (84.6% of healthy adults) (Lung et al., 1988).The association of EBV with malignant diseases has been extended to nasal T/NK-cell lymphoma (Harabuchi et al., 1990;Tao et al., 1995;Tomita et al., 1995;Peh et al., 1995;Kanavaros et al., 1996) and approximately 7-18% of gastric cancers (Tokunaga et al., 1993;Fukayama et al., 1994;Ott et al., 1994;Yuen et al., 1994;Harn et al., 1995). However, the prevalent strain(s) in these malignancies has not been fully evaluated. In this report, we describe the prevalent strain in EBV-related malignancies and in healthy adults in Southern Japan.
MATERIAL AND METHODS
SpecimensThroat washings were collected from a total of 153 healthy students by gargling with 15 ml of phosphate-buffered saline (PBS). Seropositivity to EBV antibodies was not screened. Seventythree EBV-related (EBER-1-positive) gastric cancers were collected at the...
