Occurrence of the European subgroup of subtype I BK polyomavirus in Japanese-Americans suggests transmission outside the family

Complete Genome Sequence of Original Material Used To Derive the WHO International Standard for Human Polyomavirus BK DNA

The complete genomic sequence was determined for the original biological material used to derive the WHO international standard for BK polyomavirus (BKV) DNA. The entire coding sequence and noncoding regions were assigned BKV subtype 1, subgroup 1b-1. This information will aid development and evaluation of human BKV DNA amplification assays.

The complete genomic sequence was determined for the original biological material used to derive the WHO international standard for BK polyomavirus (BKV) DNA. The entire coding sequence and noncoding regions were assigned BKV subtype 1, subgroup 1b-1. This information will aid development and evaluation of human BKV DNA amplification assays.

BK polyomavirus: a review of the virology, pathogenesis, clinical and laboratory features, and treatment

BK polyomavirus (BKPyV) is a non-enveloped, circular dsDNA virus with a genome of approximately 5100 base pairs. It can be divided into four major genotypes, but the effects of different genotypes on clinical disease are uncertain. Primary BKPyV infection is generally acquired asymptomatically in childhood. It establishes low-level persistence in many tissues, particularly the genitourinary tract. Reactivation can lead to severe disease including BKPyV-associated nephropathy confirmed by renal biopsy, hemorrhagic cystitis and meningoencephalitis. Nucleic acid amplification testing of blood and urine is the main diagnostic and prognostic test for BKPyV infection. The treatment of BKPyV infection has concentrated on reduction in immunosuppressive therapy. Recent studies suggest that antiviral drugs have demonstrated only modest benefit, but adoptive T-cell therapies offer potential advances.

Optimisation and analysis of polymerase chain reaction based DNA sequencing for genotyping polyoma virus in renal transplant patients: a report from South India

PURPOSE

To optimise a polymerase chain reaction (PCR) based DNA sequencing technique for genotyping polyoma virus in clinical specimens obtained from renal transplant patients.

MATERIALS AND METHODS

A hundred and thirty (106 peripheral blood and 24 urine) clinical specimens collected from renal transplant patients were included in the study for detecting the presence of  DNA of BK virus (BKV), JC virus (JCV) by PCR targeting the viral protein 1 (VP1) gene. PCR based DNA sequencing was performed to determine the genotypes of polyoma virus and subjected to bioinformatics analysis to determine the amino acid sequences and screen for mutations in the VP1 gene.

RESULTS

Polyoma virus was detected in 23 (17.69%) specimens of which 19 (82.60%) were positive for BK virus, 3 (13.04%) for JC virus and 1 for both BK and JC virus. PCR based DNA sequencing detected BK virus genotype I in 12 (50%), genotype IV in 8 (33.3%) and JC virus in 4 (16.6%) clinical specimens. BKV genotype I was the predominant genotype (64.2% in peripheral blood and 33.33% in urine) prevalent in south India. Six novel mutations were found--at position 29, 30 to 47 of BKV genotype I; at position 11 and 15 of BKV genotype IV and at position 2 and 30 of JCV.

CONCLUSION

BKV genotype I is the prominent genotype in India and novel mutations detected in the VP1 gene of BKV and JCV are being reported for the first time in literature.

Prevalence and Distribution of BK virus Subtypes in Renal Transplant Recipients Referred to Golestan Hospital in Ahvaz, Iran

BACKGROUND

BK virus (BKV) belongs to the human Polyomaviridae and the primary BKV infection is occurred during childhood then the virus could be latent through life, especially in the kidneys and urinary system. It became reactive after an immunocompromised status, such as pregnancy or transplantation. Isolated BKV from different locations of the world is grouped into four subtypes using serological and genotyping methods. The BKV subtype I is the dominant one and has worldwide distribution.

OBJECTIVES

According to our knowledge, there are no data about the BKV prevalence and its genotypes in southwest part of Iran. Considering the high prevalence of renal failure and kidney transplant patients in this part, and the role of BKV in graft rejection, this study aimed to determine the prevalence of BKV infection in renal transplant recipients referred to Golestan Hospital in Ahvaz City, Iran.

PATIENTS AND METHODS

Urine samples were collected from 122 kidney transplant recipients referred to Golestan Hospital in Ahvaz, southwest of Iran. The extracted DNA was amplified by Polymerase Chain Reaction, and subtype of each positive sample was determined using Restriction Fragment Length Polymorphism (RFLP) and sequencing methods.

RESULTS

From all study population, 51/122 (41.8%) urine samples were positive for BKV DNA and the other samples were negative (71/122). Forty-eight cases (94.11%) were subtype I and 3 others (5.89%) were subtype IV using the RFLP method. None of the patient's urine samples were positive for subtypes II and III.

CONCLUSIONS

Our work is the second study in Iran and considering huge numbers of transplantation in Iran and Khuzestan Province, south western of Iran, in addition to the role of this virus in kidney transplant rejection, routine evaluation of BKV positivity is recommended both for graft recipient and donors. This helps better transplantation result and may prevent graft rejection.

Migration of plant viruses: Time correlations with the agriculture history and human immigration

In this review, I made the phylodynamic comparisons of three plant viruses, Turnip mosaic virus (TuMV), Cauliflower mosaic virus (CaMV) and Cucumber mosaic virus (CMV), using the genomic sequences of a large numbers of isolates collected worldwide. We analyzed these genomic nucleotide sequences, in combination with published sequences, to estimate the timescale and rate of evolution of the individual genes of TuMV, CaMV and CMV. The main hosts of the viruses are Brassicaceae crops. We also compared these estimates from complete sequences with those from which non-synonymous and invariate codons had been removed. Our analyses provided a preliminary definition of the present geographical structure of three plant virus populations in the world, and showed that the time of migration of three plant viruses correlate well with agriculture history and human immigration.

[Plant potyvirus evolution: the survey of the genetic structure of populations]

The Potyvirus is the largest genus of the largest family of plant RNA viruses, the Potyviridae. The potyviruses infect not only dicotyledonous but also monocotyledonous plants. The potyvirus phylogeny shows that the genus probably originated from a virus of monocotyledonous plants and that it first diverged approximately 7250 years ago in Southwest Eurasia or North Africa. Turnip mosaic virus (TuMV) belongs to the genus Potyvirus and infects a wide range of plant species, most from the family Brassicaceae. TuMV is most studied a potyvirus species for molecular evolution and the genetic structure of populations. The use of computer programs for better understanding of the evolution and the genetic structures of populations of potyviruses and TuMV are illustrated.

Human polyomavirus reactivation: disease pathogenesis and treatment approaches

JC and BK polyomaviruses were discovered over 40 years ago and have become increasingly prevalent causes of morbidity and mortality in a variety of distinct, immunocompromised patient cohorts. The recent discoveries of eight new members of the Polyomaviridae family that are capable of infecting humans suggest that there are more to be discovered and raise the possibility that they may play a more significant role in human disease than previously understood. In spite of this, there remains a dearth of specific therapeutic options for human polyomavirus infections and an incomplete understanding of the relationship between the virus and the host immune system. This review summarises the human polyomaviruses with particular emphasis on pathogenesis in those directly implicated in disease aetiology and the therapeutic options available for treatment in the immunocompromised host.

Absence of association between the incidence of BK virus and sporadic Creutzfeldt-Jakob disease

BACKGROUND

Many studies suggest that the virus-like particles are required for the infection of Creutzfeldt-Jakob disease (CJD).

OBJECTIVE

To determine the relationship between BK polyomavirus (BKV) and sporadic CJD.

MATERIALS AND METHODS

We investigated the prevalence of BKV in urine samples from 94 sporadic CJD patients and 54 other neurological disease (OND) patients using polymerase chain reaction.

RESULTS

BKV DNA was detected in 16 (17%) and 9 (16.7%) urine samples from sporadic CJD and OND patients, respectively. There was no significant difference in the incidence of BKV infection between Korean sporadic CJD and OND patients (p = 0.9558). In order to investigate the genotypes of BKV, we analyzed 22 BKV isolates obtained from Korean patients by DNA sequencing and nucleotide sequence analysis. Three distinct subtypes, namely I, III, and IV, were found in 66.7, 22.2, and 11.1% of 9 BKV isolates from OND patients, whereas subtypes I and IV were detected in 76.9 and 23.1% of 13 BKV isolates from sporadic CJD patients. Interestingly, subtype III was not detected in sporadic CJD patients. Significant differences in the frequency of BKV genotypes were not observed between sporadic CJD and OND patients.

CONCLUSIONS

These results indicate that BKV may not play an important role in the pathogenesis of prion diseases.

Molecular and phylogenetic analyses of human Parvovirus B19 isolated from Brazilian patients with sickle cell disease and β-thalassemia major and healthy blood donors

Human Parvovirus B19 (B19V) is a recognized cause of life-threatening conditions among patients with hemoglobinopathies. This study investigates B19V infection in patients with sickle cell disease and β-thalassemia using different experimental approaches. A total of 183 individuals (144 with sickle cell disease and 39 with β-thalassemia major) and 100 healthy blood donors were examined for B19V using anti-B19V IgG enzyme immunoassay, quantitative PCR, DNA sequencing, and phylogenetic analysis. Viremia was documented in 18.6% of patients and 1% of donors, and was generally characterized by low viral load (VL); however, acute infections were also observed. Anti-B19V IgG was detected in 65.9% of patients with sickle cell disease and in 60% of donors, whereas the patients with thalassemia exhibited relatively low seroreactivity. The seroprevalence varied among the different age groups. In patients, it progressively increased with age, whereas in donors it reached a plateau. Based on partial NS1 fragments, all isolates detected were classified as subgenotype 1A with a tendency to elicit genetically complex infections. Interestingly, quasispecies occurred in the plasma of not only patients but also donors with even higher heterogeneity. The partial NS1 sequence examined did not exhibit positive selection. Quantitation of B19V with a conservative probe is a technically and practically useful approach. The extensive spread of B19V subgenotype 1A in patients and donors and its recent introduction into the countryside of the São Paulo State, Brazil were demonstrated; however, it is difficult to establish a relationship between viral sequences and the clinical outcomes of the infection.

Phylogenetic analysis of the complete genome of 11 BKV isolates obtained from allogenic stem cell transplant recipients in Ireland

BK polyomavirus (family Polyomaviridae) may cause hemorrhagic cystitis (BKV-HC) in hematopoietic stem cell transplant recipients. Eleven complete BKV genomes (GenBank accession numbers: JN192431-JN192441) were sequenced from urine samples of allogenic hematopoietic stem cell transplant recipients and compared to complete BKV genomes in the published literature. Of the 11 isolates, seven (64%) were subgroup Ib-1, three (27%) isolates belonged to subgroup Ib-2 and a single isolate belonged to subtype III. The analysis of single-nucleotide polymorphisms in this study showed that isolates could be subclassified into subtypes I-IV and subgroups Ib-1 and Ib-2 on the basis of VP1 of the first part of the Large T-antigen (LTag). The non-coding control region (NCCR) of the 11 isolates was also sequenced. These sequences showed that there was consistent sequence homology within subgroups Ib-1 and Ib-2. Two new mutations were described in the isolates, G→C at O(84) in isolate SJH-LG-310, and a deletion at R(2-7) in isolate SJH-LG-309. No known transcription factor is thought to be present at the site of either of these mutations. There were no rearrangements seen in isolates and this may be because the patients were not followed up over time. There were five nucleotide positions at which subgroup Ib-1 isolated differed from subgroup Ib-2 isolates in the NCCR sequence, O(41) , P(18) , P(31) , R(4) , and S(18) . The mutation O(41) is present in the promoter granulocyte/macrophage stimulating factor) gene and the P(31) mutation is present in the NF-1 gene.

Distribution of BK polyomavirus genotypes in Tunisian renal transplant recipients

BK polyomavirus (BKV) is a ubiquitous virus in humans that remains latent in the urogenital tract after a primary infection during childhood. The virus, which is reactivated frequently and excreted in urine, can cause nephropathy in renal transplant recipients. BKV sequences are classified into four subtypes (I-IV). Subtype I and IV are divided further into four and six subgroups, respectively. To characterize the subtypes of BKV prevalent in Tunisia, the presence of the virus was investigated by real-time PCR in urine samples from 77 renal transplant recipients. For subtype identification, a DNA fragment in the VP1 coding region, amplified by nested PCR from positive samples, was sequenced and a phylogenetic analysis was performed. In the studied population, subtype I (75.5%), II (14.5%), and IV (2.5%) were identified with a clear predominance of subtype Ib-2 (73%) as observed in European population. This study suggests that in North Africa, the BKV genotype distribution is similar to that of Europe and different from that of sub-Saharan Africa.

[Urologic aspects of Polyomavirus infection]

JC virus (JCV) and BK virus (BKV) are human Polyomaviruses of the papovavirus family, which also includes a simian vacuolating virus 40 (SV40). Human Polyomaviruses were first isolated in 1971 from the brain (JCV) and urine (BKV) of two different patients. Human Polyomaviruses have a limited and specific tissue tropism infecting the renal tubular cells, the urothelium, the B cells and the brain cells. The virus infects the majority of the human population with seroconversion occurring during adolescence. The detection of the virus may be cytological, pathological, virological or immunological. Following a typically subclinical primary infection, Polyomavirus establishes a life-long persistent infection, especially in the urinary tract. BKV is known to reactivate and cause severe disease in immunosuppressed patients. The presence of Polyomavirus outside conditions of immunosuppression raises the question of its meaning and its therapeutic management. Given the ubiquitous nature of the virus and its strong association with cancer in animal models, they may play an etiological role in human malignancies. Here, we describe the biology of human Polyomaviruses, review their non-malignant and malignant potentials, and discuss the therapeutic aspect.

Evolution of the BK polyomavirus: epidemiological, anthropological and clinical implications

BK polyomavirus (BKV) is essentially ubiquitous in all human populations worldwide. Asymptomatic infection with this virus occurs during early childhood, leading to life-long persistence in the kidney. BKV has four subtypes that can be identified using serological and genotyping methods. The evolutionary aspects of BKV have remained poorly understood due to the limited availability of BKV genomes, since urinary excretion of BKV DNA is detected primarily in immunocompromised individuals. However, we have found that BKV DNA sequences can often be amplified from non-immunocompromised elderly individuals, using a highly sensitive polymerase chain reaction (PCR) with highly concentrated urinary DNA as the source of viral DNA. Using this approach, we have PCR-amplified and sequenced a large number of partial and complete BKV genomes from various human populations worldwide and conducted a series of evolutionary studies using these sequences. We have shown that subtypes I and IV evolved into four and six subgroups, respectively, with each having a close relationship with a particular human population. In addition, we have provided evidence supporting the hypothesis that BKV strains with the archetypal transcriptional control region (TCR) circulate in the human population. In this review, we describe these findings and discuss their epidemiological, anthropological and clinical implications.

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

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 in urine, 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 to be transmitted not only within but also outside the family. In the present study, to clarify 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-1 and Ic, 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 findings may reflect the recent transmission of BKV Ia strains to Japanese children.

Population genetic tests suggest that the epidemiologies of JCV and BKV are strikingly different

The JCV and BKV viruses have been used as markers for the study of human evolution by assuming that these viruses coevolved with their host. However, it is currently unclear whether the details of the population expansion of these viruses and humans agree. To study this in more detail, large numbers of complete genomes were used for population genetic tests to detect evidence for population expansion. Relative to the neutral expectation of no selective forces and no demographic changes, the JCV data set contained a striking excess of synonymous and non-synonymous mutations that occur only once in the data set. The same was found for non-synonymous mutations of BKV, but not at all for synonymous mutations of BKV. The different frequency spectra of mutations in JCV and BKV do not result from the inclusion of patients with clinical symptoms associated with BKV and JCV, such as nephropathy or progressive multifocal leucoencefalopathy, nor from the different numbers of genomes available for JCV and BKV. Instead, the distribution of unique mutations and population genetic models that use older mutation classes indicate a striking difference of the historical demographies of JCV and BKV with only the former virus exhibiting the evidence of demographic expansion. Our analyses expand on recent population genetic analyses that document a global population expansion of JCV by taking into account the impact of deleterious mutations and by comparing both human viruses. The striking difference between the demographics of BKV and JCV suggests that important aspects of their epidemiology remain to be discovered.

Comparison of the distribution patterns of BK polyomavirus lineages among China, Korea and Japan: implications for human migrations in northeast Asia

BKV is widespread among humans, infecting children asymptomatically and then persisting in renal tissue. Based on the serological or phylogenetic method, BKV isolates worldwide are classified into four subtypes (I-IV), with subtypes I and IV further divided into several genetically-distinct subgroups. Since, similarly to JCV, a close relationship exists between BKV lineages and human populations, BKV should be useful as a marker to trace human migrations. To elucidate ancient human migrations in northeast Asia, urine samples were collected from immunocompetent elderly patients in Shanghai, China; Anyang, South Korea; and various locations in Japan. Partial and complete BKV genomes from these samples were amplified and sequenced using PCR, and the determined sequences were classified into subtypes and subgroups by phylogenetic and SNP analyses. In addition, based on an SNP analysis, the major subtype I subgroup (I/c) was classified into two subdivisions, I/c/Ch and I/c/KJ. The distribution patterns of BKV subgroups and subdivisions among the three regions were compared. Some aspects of the subgroup and subdivision distribution were more similar between Korea and Japan, but others were more similar between China and Korea or between China and Japan. Based on these findings, we inferred various northeast Asian migrations. Most of the JCV-based inferences of northeastern Asian migrations were consistent with those based on BKV, but the previously suggested migration route from the Asian continent to the Japanese archipelago seemed to need revision.

Biologic diversity of polyomavirus BK genomic sequences: Implications for molecular diagnostic laboratories

Data on polyomavirus genomic diversity has greatly expanded in the past few years. The implications of viral DNA sequence variation on the performance of molecular diagnostic assays have not been systematically examined. 716 BK, 1626 JC, and 73 SV40 virus sequences available in GenBank were aligned using Clustal-X. Five different published BKV PCR assays currently in use at major medical centers were evaluated for primer and probe mismatches with available GenBank sequences. Coverage of naturally occurring BKV strains varied amongst different assay methods. Targeted viral sequences showed major mismatch with primer or probe sequence in up to 30.7% of known BKV strains. BKV subtypes IVa, IVb, and IVc were more prone to this problem, reflecting common use of Type I Dun sequence for assay design. Despite the known polymorphism of this gene, 484 VP-1 sequences with conserved areas potentially suitable for PCR assay design are available. Assay targets in the Large T-antigen and agnogene are less subject to genetic variation, but sequence information corresponding to the latter two genes is available only for 164 and 174 published strains, respectively. Cross reactivity of appropriately selected BKV primers with JCV and SV40 sequences available in current databases was not a significant problem.

Conserved archetypal configuration of the transcriptional control region during the course of BK polyomavirus evolution

BK polyomavirus (BKV) is widespread among humans, asymptomatically infecting children and then persisting in renal tissue. The transcriptional control region (TCR) of the BKV genome is variable among clinical isolates. Thus, archetypal TCRs with a common basic configuration generally occur in BKV isolates from the urine of immunocompromised patients, but rearranged TCRs that possibly arise from the archetypal configuration have also been detected in clinical specimens. To examine the hypothesis that archetypal strains represent wild-type strains circulating in the human population (the archetype hypothesis), we analysed 145 complete viral genomes amplified directly from the urine of non-immunocompromised individuals worldwide. These genomes included 82, three, two and 58 sequences classified as belonging to subtypes I, II, III and IV, respectively. Rearranged TCRs with long duplications or deletions were detected from two subtype I and two subtype IV genomes, but not from the other 141 genomes (thus, the TCRs of these genomes were judged to be archetypal). The variations in the archetypal TCRs were nucleotide substitutions and single-nucleotide deletions, most of which were unique to particular subtypes or subgroups. We confirmed that the four complete BKV genomes with rearranged TCRs did not form a unique lineage on a phylogenetic tree. Collectively, the findings demonstrate that the archetypal TCR configuration has been conserved during the evolution of BKV, providing support for the archetype hypothesis. Additionally, we suggest that 'archetype' should be used as a conceptual term that denotes a prototypical structure that can generate various rearranged TCRs during viral growth in vivo and in vitro.