Identification of a genomic subgroup of BK polyomavirus spread in European populations

Abstract

BK polyomavirus (BKV) is highly prevalent in the human population, infecting children without obvious symptoms and persisting in the kidney in a latent state. In immunosuppressed patients, BKV is reactivated and excreted in urine. BKV isolates worldwide are classified into four serologically distinct subtypes, I-IV, with subtype I being the most frequently detected. Furthermore, subtype I is subdivided into subgroups based on genomic variations. In this study, the distribution patterns of the subtypes and subgroups of BKV were compared among four patient populations with various immunosuppressive states and of various ethnic backgrounds: (A) Finnish renal-transplant recipients; (B) Irish/English haematopoietic stem-cell transplant recipients with and without haemorrhagic cystitis; (C) Japanese renal-transplant recipients; and (D) Japanese bone-marrow transplant recipients. The typing sequences (287 bp) of BKV in population A were determined in this study; those in populations B-D have been reported previously. These sequences were subjected to phylogenetic and single nucleotide polymorphism analyses. Based on the results of these analyses, the BKV isolates in the four patient populations were classified into subtypes and subgroups. The incidence of subtype IV varied significantly among patient populations. Furthermore, the incidence of subgroup Ib-2 within subtype I was high in populations A and B, whereas that of Ic was high in populations C and D (P<0?01). These results suggest that subgroup Ib-2 is widespread among Europeans, whereas Ic is unique to north-east Asians. Furthermore, a phylogenetic analysis based on complete BKV DNA sequences supported the hypothesis that there is geographical separation of European and Asian BKV strains.

Mutations in the BC‐loop of the BKV VP1 region do not influence viral load in renal transplant patients

“…BKV strains of subtype I (66.64%) and subtype IV were detected in our samples. This result corresponds to the distribution of BKV subtypes in Europe analyzed in previous studies [Ikegaya et al, 2006;Krumbholz et al, 2006]. Subgroup Ib-2 BKV isolates are the most prevalent BKV strains in our German cohort (60.00%).…”

“…Subtype I is worldwide predominant and is divided into the subgroups Ia, Ib, and Ic. Subtype IV is detected at lower rates and the subtypes II and III only rarely occur [Takasaka et al, 2004;Ikegaya et al, 2006]. Strains of subtype I replicate in cell culture more efficiently than strains of subtype IV [Nukuzuma et al, 2006].…”

Genotyping Schemes for Polyomavirus BK, Using Gene-Specific Phylogenetic Trees and Single Nucleotide Polymorphism Analysis

“…As our knowledge of BKV genomic diversity expanded, difficulties were encountered in assigning viral strains to existing subtypes (1,27). Investigators proposed additional subgroups within the four major subtypes, such as subgroups Ia and Ib (35); Ic (36); and IVa, IVb, and IVc (14,25). Robust biologic and statistical support was not always available for the proposed subgroups.…”

A Simple and Reliable Strategy for BK Virus Subtyping and Subgrouping

“…The distribution of BKV subtypes and subgroups in human populations has been studied in many countries (7)(8)(9). BKV subtype I subgroup distributions vary across countries; subgroup Ia is highly prevalent in Africa, subgroup Ib-1 is highly prevalent in southeast Asia, subgroup Ib-2 is highly prevalent in Europe, and subgroup Ic is highly prevalent in northeast Asia (10,11). As with subtype I, each subtype IV subgroup has a specific geographic distribution (6).…”