Occurrence of the African subgroup (Ia) of BK polyomavirus in younger Japanese children

Abstract

BK polyomavirus (BKV) is ubiquitous among humans, usually infecting them asymptomatically during childhood. BKV persists in renal tissue of individuals and their progeny are excreted inurine, particularly in immunocompromised patients. JC virus, another human polyomavirus, has been considered to be transmitted from parents to children during prolonged cohabitation. However, BKV has been supposed tobe transmitted not only within but also outside the family. Inthepresent study, toclarify this possibility, we analyzed phylogenetically 35 BKV which were excreted in the urine by Japanese children and adults undergoing stem cell transplantation. Subtypes I, III and IV were detected in 15, two and one children and in 15, one and one adults, respectively. Among 15 subtype I isolates from children, three, four and eight belonged to subgroups Ia, Ib-1andIc, respectively. All the three children from whom Ia was detected were less than 9 years old. In contrast in the adults, three subtype I belonged to Ib-1 and the other 12 to Ic. These findingsmay reflect the recent transmission of BKV Ia strains to Japanese children. © 2008 The Societies and Blackwell Publishing Asia Pty Ltd.