BK polyomavirus (BKV) is ubiquitous 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 have been classified into four subtypes (I-IV) using either serological or genotyping methods. To elucidate the subtypes of BKV prevalent in Japan, the 287 bp typing region in the viral genome was PCR-amplified from urine samples of 45 renal transplant (RT) and 31 bone-marrow transplant (BMT) recipients. The amplified fragments were subjected to a phylogenetic or RFLP analysis to determine the subtypes of BKV isolates in urine samples. Subtypes I, II, III and IV were detected, respectively, in 70-80, 0, 2-3 and 10-20 % of the BKV-positive patients in both patient groups. This pattern of distribution was virtually identical to patterns previously demonstrated in England, Tanzania and the United States, suggesting that BKV subtypes are distributed similarly in various human populations. Furthermore, transcriptional control regions (TCRs) were PCR-amplified from the urine samples of 25 RT and 20 BMT recipients, and their nucleotide sequences were determined. The basic TCR structure (the so-called archetype configuration) was observed in most isolates belonging to subtypes I, III and IV (subtype II isolates were not available), albeit with several nucleotide substitutions and a few single-nucleotide deletions (or insertions). Only three TCRs carried extensive sequence rearrangements. Thus, it was concluded that the archetypal configuration of the BKV TCR has been conserved during the evolution of BKV.

The current survey revealed that the rate of successful pregnancy in women on dialysis has improved. More than half of the pregnancies resulted in infant survival. But, premature birth is a major problem for the children of women on dialysis and there is a higher rate of neonatal death. There are significant differences in gestational age, birth weight, frequency and severity of prematurity and rates of neonatal death between pregnancies of women undergoing dialysis and those who are renal transplant recipients.

Several protocols allow the successful ABO incompatible living-related kidney transplantation (ABO-ILKTWe compared the patient and graft survival rates as well as the incidence rate of acute rejection in these two eras, when different regimens were used. There were significant differences in the 1-and 5-year graft survival rates between groups 1 and 2 (1-year: 78% in group 1 vs. 94% in group 2; 5-year: 73% in group 1 vs. 90% in group 2, p = 0.008). Also, a higher incidence rate of acute rejection was significantly observed in group 1 (50/105, 48%) than in group 2 (18/117, 15%) (p < 0.001). We conclude that the FK/MMF combination regimen provides excellent graft survival results in ABO-ILKT.

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All contributing authors have declared that there is no relationship with any companies and no conflict of interest in this study.Numerous studies have shown that protocol biopsies have predictive power. We retrospectively examined the histologic findings and C4d staining in 89 protocol biopsies from 48 ABO-incompatible (ABO-I) transplant recipients, and compared the results with those of 250 controls from 133 ABO-compatible (ABO-C) transplant recipients given equivalent maintenance immunosuppression. Others have shown that subclinical rejection (borderline and grade I) in ABO-C grafts decreased gradually after transplantation. In our study, however, subclinical rejection in the ABO-I grafts was detected in 10%, 14% and 28% at 1, 3 and 6-12 months, respectively. At 6-12 months, mild tubular atrophy was more common in the ABO-C grafts whereas the incidence of transplant glomerulopathy did not differ between the two groups (ABO-C: 7%; ABO-I: 15%; p = 0.57). In the ABO-I transplants, risk factors for transplant glomerulopathy in univariate analysis were positive panel reactivity (relative risk, 45.0; p < 0.01) and a prior history of antibody-mediated rejection (relative risk, 17.9; p = 0.01). Furthermore, C4d deposition in the peritubular capillaries was detected in 94%, with diffuse staining in 66%. This deposition, however, was not linked to antibody-mediated rejection. We conclude that, in the ABO-I kidney transplantation setting, detection of C4d alone in protocol biopsies might not have any diagnostic or therapeutic relevance.