Relationship between J-Western CagA subtype and the vacA m2 region of Helicobacter pylori.

摘要

Yamazaki et al. examined the full-length sequences of the vacA and cagA genes of Helicobacter pylori isolated from Okinawa, Japan (4). Among 20 Okinawan strains examined, 7 had East Asian-type CagA and 13 had Western-type CagA, in agreement with previous studies (3). Okinawa, located in the southern islands of Japan, was governed by the United States from the end of World War II until 1972, and even today there is a large U.S. population in Okinawa. The data suggest that transmission of H. pylori between different populations may not be a rare event. However, Truong et al. confirmed that 12 of 13 Western-type CagA strains in Okinawa form a cluster of strains that are different from strains isolated from Western countries (2). They therefore proposed that there is a Japanese subtype in the Western CagA type (J-Western CagA). These data suggest that all the Western-type CagA strains in Okinawa might not have derived from those in modern Western people and may have come to Japan long ago, as we speculated previously (3). Further studies will be necessary to test this hypothesis.