Genetic heterogeneity of the human papovaviruses BK and JC

A regulatory region rearranged BK virus is associated with tubulointerstitial nephritis in a rejected renal allograft

A renal allograft transplant patient with high serum creatinine presented clinical symptoms of rejection. Sections of renal biopsy tissue showed mononuclear leukocyte infiltration in the tubulointerstitium and nuclear enlargement with inclusions in the tubular epithelium. The morphological characteristics resembled polyomavirus-induced interstitial nephritis. Electron microscopy of the nuclear inclusions showed paracrystalline arrays of naked viral particles with a diameter of 45 nm. Molecular studies revealed that a new variant of BK virus (BKV) with rearrangement at the regulatory region was involved in the nephritis. The BKV regulatory region contained a tandem repeat from the P-block to the Q-block causing duplication of several important transcriptional elements or transcriptional factor binding motifs. This is the first report to show a naturally occurring BKV variant with regulatory region rearrangement associated with tubulointerstitial nephritis.

Growth efficiency of naturally occurring BK virus variants in vivo and in vitro

We molecularly cloned a number of BK virus (BKV) DNAs from urine samples collected from a patient with systemic lupus erythematosus undergoing immunosuppressive therapy. On the basis of the structure of the noncoding regulatory region, cloned viral DNAs were classified into a major group and several minor groups. The major group contained a single 68-base-pair (bp) promoter-enhancer element and a 63-bp sequence identified in the genomes of many BKV strains. Most of the minor groups retained a variety of duplications within the transcriptional control region and the origin of DNA replication. We assayed various cloned viral DNAs for the capacity to induce viral growth in transfected human embryonic kidney cells. While major viral DNAs induced slow viral replication, a minor viral DNA retaining partial duplication of the 68-bp element induced rapid viral growth. We concluded that reiteration of the promoter-enhancer element, which is required for efficient growth of BKV in cell culture, is not advantageous for replication of BKV in natural hosts.

BK virus (BKV) detection in urine specimens of immunocompromised patients: comparison between the DNA-DNA hybridization assay, the immunofluorescence test and the dot enzyme immunoassay

Three methods used for the detection of BK virus in urine specimens, the indirect immunofluorescence test, the dot enzyme immunoassay and the DNA-DNA hybridization assay, were compared by testing specimens from 49 immunocompromised patients. All three assays were effective in detecting BK virus. The technical advantage of each of them was discussed. The immunofluorescence test was found to be the simplest one to perform; the DNA-DNA hybridization assay displayed exquisite sensitivity; and the easy reading of the dot enzyme immunoassay did not require the specialized training inherent to immunofluorescence assays. The dot enzyme immunoassay might therefore be the most practical method for screening urine specimens of immunocompromised patients, especially when the sediment is poor in cells. Conversely, the indirect immunofluorescence test might be the method of choice for checking patients with haemorragic cystitis whose urine samples usually contain large amounts of cells.

Serological typing scheme for BK-like isolates of human polyomavirus

Human polyomavirus BK-like isolates were subjected to restriction endonuclease analysis with the enzymes EcoRI and Hind III. End-point dilution was used to obtain homogeneous virus pools for DNA analysis and to remove JC virus from a mixed stock. The results of Hind III digestion suggested that two subgroups could be distinguished. Several BK-like isolates were purified and rabbit antisera raised. The isolates were compared with each other and with BK and JC viruses by haemagglutination-inhibition (HI) and by neutralisation. JC virus was serologically distinct, but all the other isolates showed some cross-reactivity. Two subgroups were again evident: GS and PG were with prototype BK in subgroup 1, and MG and IV were in subgroup 2. Two isolates, AS and SB, reacted with isolates of both subgroups 1 and 2 but were distinct from one another: their genome was similar to subgroup 1 isolates. Typing by HI or by neutralisation may form a basis for grouping BK-like polyomavirus isolates.

Direct detection of the human papovavirus BK in urine of bone marrow transplant recipients: comparison of DNA hybridization with ELISA

Urine specimens from bone marrow transplant (BMT) recipients and from controls were directly tested for BK virus (BKV) DNA sequences by dot hybridization and for BKV antigen by a double-antibody indirect ELISA. A total of 158 specimens from 55 BMT patients (57 collected prior to or at the time of transplantation and 101 in the posttransplant period) and single urines from 125 control subjects were examined by both methods. A molecularly cloned, 32P-labelled BKV probe was hybridized with urine sediments that were spotted directly on nitrocellulose filters and denatured in situ. BKV DNA sequences were detected in 1 (1.8%) pretransplant and 22 (21.8%) posttransplant urines of BMT patients, and in none of control urines. In ELISA of urine supernatants, BKV antigen was detected in 1 (1.8%) pretransplant and 21 (20.8%) posttransplant urines of BMT patients and in 1 (0.8%) of the control urines. The results of the two tests correlated as follows: 16 urines were positive and 253 urines negative by both methods; seven specimens were positive by DNA hybridization only and seven were positive by ELISA alone. Virus excretion in urine was demonstrated in 20 (36.4%) patients by DNA hybridization, in 19 (34.5%) patients by ELISA, in 15 (27.3%) patients by both methods, and in 24 (44%) patients by at least one of the two tests.