4 GEOGRAPHICALLY DISTINCT GENOTYPES OF JC VIRUS ARE PREVALENT IN CHINA AND MONGOLIA - IMPLICATIONS FOR THE RACIAL COMPOSITION OF MODERN CHINA

JC polyomavirus (JCV) is ubiquitous in humans, persisting in renal tis sue and excreting progeny in urine. It has been shown that the genotyp ing of urinary JCV offers a novel means of tracing human migrations. T his approach was used to elucidate the racial composition of modern Ch ina. JCV isolates in the Old World were previously classified into nin e distinct genotypes, One of them (B1) has a wide domain, encompassing part of Europe and the entirety of Asia. By constructing a neighbour- joining phylogenetic tree, all B1 isolates detected so far were classi fied into four distinct groups (B1-a to -d), each occupying unique dom ains in the world, According to this revised classification system of JCV DNAs, four genotypes (CY, SC, B1-a and -b) were found to be preval ent in China and Mongolia (Mongolia was studied instead of Inner Mongo lia, which is part of China). There was a remarkable variation in the incidence of genotypes among the sites of sample collection. CY was mo re frequently detected in Northern China, SC was predominant in Southe rn China and B1-b was detected only in Mongolia, B1-a was spread throu ghout China. These data were statistically analysed and the observed r egional differences in the incidence of genotypes were found to be sig nificant. It is likely that these differences in JCV distribution in C hina reflect the intermingling of different population groups that con stitute modern China.