| polyomavirus jc genotypes in an urban united states population reflect the history of african origin and genetic admixture in modern african americans. | the human polyomavirus jc (jc virus), a small, circular, double-stranded dna virus, has a worldwide distribution and is excreted harmlessly in urine by 20% to 70% of adults. dna sequence analysis has identified seven distinct genotypes that likely coevolved with modern humans, although the mode of virus transmission is unknown. type 1 is european in its distribution. types 2 and 7 are asian, while types 3 and 6 are african. type 4, closely related to type 1, is of uncertain origin, having been f ... | 2000 | 11126728 |