Comparison of the distribution patterns of BK polyomavirus lineages among China, Korea and Japan: Implications for human migrations in northeast Asia

BKV is widespread among humans, infecting children asymptomatically and then persisting in renal tissue. Based on the serological or phylogeneticmethod, BKV isolates worldwide are classified into four subtypes (I-IV),with subtypes I and IV furtherdivided into several genetically-distinct subgroups. Since, similarly to JCV, a close relationship exists between BKV lineages and human populations, BKV should be useful as a marker to trace human migrations. To elucidate ancient human migrations in northeast Asia, urine sampleswere collected fromimmunocompetent elderly patients in Shanghai,China; Anyang, SouthKorea; and various locations in Japan. Partial and completeBKVgenomes fromthese samples were amplified and sequenced using PCR, and the determined sequences were classified into subtypes and subgroups by phylogenetic and SNP analyses. In addition, based on an SNP analysis, the major subtype I subgroup (I/c) was classified into two subdivisions, I/c/Ch and I/c/KJ. The distribution patterns of BKV subgroups and subdivisions among the three regions were compared. Some aspects of the subgroup and subdivision distribution weremore similar between Korea and Japan, but others weremore similar between China and Korea or between China and Japan. Based on these findings, we inferred various northeast Asian migrations. Most of the JCV-based inferences of northeastern Asian migrations were consistent with those based on BKV, but the previously suggested migration route from the Asian continent to the Japanese archipelago seemed to need revision.