Latent BK virus infection and Kaposi's sarcoma pathogenesis

Inhibitory KIR2DL2 receptor and HHV-8 in classic or endemic Kaposi sarcoma

KIR2DL2, an inhibitory Killer cell Immunoglobulin-like Receptor (KIR), has been shown to predispose to the development of several herpesvirus-associated diseases by inhibiting the efficiency of Natural Killer (NK) cells against virus-infected cells. The aim of this observational study was to assess the prevalence of KIR2DL2 and Human Herpes Virus 8 (HHV8) in patients affected with classical and endemic Kaposi sarcoma (KS), as well as in controls. Blood samples collected from 17 Caucasian, HIV-negative, immunocompetent patients affected with classical KS (c-KS), 12 African, HIV-negative patients with endemic KS (e-KS), 83 healthy subjects and 26 psoriatic patients were processed for genotypization by PCR for two KIR alleles, such as KIR2DL2 and KIR2DL3 and analyzed for HHV-8 presence. The totality of both c-KS and e-KS patients presented HHV-8 infection, whereas HHV8 was found in 26.9% of psoriatic subjects and 19.3% of healthy subjects. KIR2DL2 was found in the 76.5% of c-KS subjects, while the receptor was found in 41.7% of the e-KS group, 34.6% of psoriatic patients and 43.4% of healthy controls (p < 0.0001). A significantly higher prevalence of KIR2DL2 in c-KS patients than in all the other subjects was also confirmed comparing age-matched groups. Based on these results, the inhibitory KIR2DL2 genotype appears to be a possible cofactor which increases the risk of developing c-KS in HHV8-positive, immunocompetent subjects, while it seems less relevant in e-KS pathogenesis.

Human seminal virome: a panel based on recent literature

Background

The seminal virome and its implications for fertility remain poorly understood. To date, there are no defined panels for the detection of viruses of clinical interest in seminal samples.

Results

In this study, we characterized the human seminal virome based on more than 1,000 studies published over the last five years.

Conclusions

The number of studies investigating viruses that occur in human semen has increased, and to date, these studies have been mostly prospective or related to specific clinical findings. Through the joint analysis of all these studies, we have listed the viruses related to the worsening of seminal parameters and propose a new panel with the main viruses already described that possibly affect male fertility and health. This panel can assist in evaluating semen quality and serve as a tool for investigation in cases of infertility.

BK virus: Current understanding of pathogenicity and clinical disease in transplantation

BK polyomavirus (BKV) is an important cause of graft loss in renal transplant recipients that continues to pose a significant challenge to clinicians due to its frequently unpredictable onset, persistence, and the lack of effective antiviral agents or prevention strategies. This review covers our current understanding of epidemiology, viral transmission and disease progression, and treatment and prevention strategies that have been used to manage this disease.

Human polyomavirus DNA detection in keratoacanthoma and Spitz naevus: no evidence for a causal role

Keratoacanthomas (KA) and Spitz naevus (SN) are both lesions with unknown aetiology; therefore, the possibility of a viral involvement, more specifically the involvement of human polyomaviruses (HPyV), was investigated. In total, 22 cases of KA and 25 cases of SN were tested for the presence of HPyVs. DNA was extracted and amplified by multiplex PCR and thereafter tested with a multiplex bead-based assay for HPyVs (BKPyV, JCPyV, KIPyV, WUPyV, MCPyV, TSPyV, HPyV6, 7 and 9) and two primate viruses (SV40 and LPyV). HPyV DNA was found in 20 of the 47 lesions. There was no significant difference in HPyV DNA detection frequency between patients diagnosed with KA and patients diagnosed with SN, nor any over-representation of a specific HPyV type in any of the two patient categories. In conclusion, evidence for a specific aetiological role of any of the above tested HPyVs in either KA or SN was not disclosed.

Human polyomaviruses and incidence of cutaneous squamous cell carcinoma in the New Hampshire skin cancer study

Squamous cell carcinoma (SCC) of the skin is a malignancy arising from epithelial keratinocytes. Experimental and epidemiologic evidence raise the possibility that human polyomaviruses (PyV) may be associated with the occurrence of SCC. To investigate whether the risk for SCC was associated with PyV infection, seropositivity to 10 PyV types was assessed following diagnosis in a population-based case-control study conducted in the United States. A total of 253 SCC cases and 460 age group and gender-matched controls were included. Antibody response against each PyV was measured using a multiplex serology-based glutathione S-transferase capture assay of recombinantly expressed VP1 capsid proteins. Odds ratios (OR) for SCC associated with seropositivity to each PyV type were estimated using logistic regression, with adjustment for potentially confounding factors. SCC cases were seropositive for a greater number of PyVs than controls (P = 0.049). Those who were JC seropositive had increased odds of SCC when compared to those who were JC seronegative (OR = 1.37, 95% CI: 0.98-1.90), with an increasing trend in SCC risk with increasing quartiles of seroreactivity (P for trend = 0.04). There were no clear associations between SCC risk and serostatus for other PyV types. This study provides limited evidence that infection with certain PyVs may be related to the occurrence of SCC in the general population of the United States.

Prospective Study of Human Polyomaviruses and Risk of Cutaneous Squamous Cell Carcinoma in the United States

BACKGROUND

Merkel cell polyomavirus (PyV) is causally related to Merkel cell carcinoma, a rare skin malignancy. Little is known about the serostability of other PyVs over time or associations with cutaneous squamous cell carcinoma (SCC).

METHODS

As part of a U.S. nested case-control study, antibody response against the PyV VP1 capsid proteins of BK and John Cunningham virus (JC) was measured using multiplex serology on 113 SCC cases and 229 gender, age, and study center-matched controls who had a prior keratinocyte cancer. Repeated serum samples from controls and both pre and postdiagnosis samples from a subset of SCC cases were also tested. Odds ratios (OR) for SCC associated with seropositivity to each PyV type were estimated using conditional logistic regression.

RESULTS

Among controls, BK and JC seroreactivity was stable over time, with intraclass correlation coefficients of 0.86 for BK and 0.94 for JC. Among cases, there was little evidence of seroconversion following SCC diagnosis. JC seropositivity prior to diagnosis was associated with an elevated risk of SCC (OR = 2.54; 95% CI, 1.23-5.25), and SCC risk increased with increasing quartiles of JC (Ptrend = 0.004) and BK (Ptrend = 0.02) seroreactivity.

CONCLUSIONS

PyV antibody levels were stable over time and following an SCC diagnosis. A history of PyV infection may be involved in the occurrence of SCC in a population at high risk for this malignancy.

IMPACT

A single measure of PyV seroreactivity appears a reliable indicator of long-term antibody status, and PyV exposure may be a risk factor for subsequent SCC. Cancer Epidemiol Biomarkers Prev; 25(5); 736-44. ©2016 AACR.

Polyoma BK Virus: An Oncogenic Virus?

We report a case of a 65-year-old gentleman with a history of end stage renal disease who underwent a successful cadaveric donor kidney transplant four years ago. He subsequently developed BK virus nephropathy related to chronic immunosuppressant therapy. Three years later, misfortune struck again, and he developed adenocarcinoma of the bladder.

Association between the JC polyomavirus infection and male infertility

In recent years the incidence of male infertility has increased. Many risk factors have been taken into consideration, including viral infections. Investigations into viral agents and male infertility have mainly been focused on human papillomaviruses, while no reports have been published on polyomaviruses and male infertility. The aim of this study was to verify whether JC virus and BK virus are associated with male infertility. Matched semen and urine samples from 106 infertile males and 100 fertile males, as controls, were analyzed. Specific PCR analyses were carried out to detect and quantify large T (Tag) coding sequences of JCV and BKV. DNA sequencing, carried out in Tag JCV-positive samples, was addressed to viral protein 1 (VP1) coding sequences. The prevalence of JCV Tag sequences in semen and urine samples from infertile males was 34% (72/212), whereas the BKV prevalence was 0.94% (2/212). Specifically, JCV Tag sequences were detected in 24.5% (26/106) of semen and 43.4% (46/106) of urine samples from infertile men. In semen and urine samples from controls the prevalence was 11% and 28%, respectively. A statistically significant difference (p<0.05) in JCV prevalence was disclosed in semen and urine samples of cases vs. controls. A higher JC viral DNA load was detected in samples from infertile males than in controls. In samples from infertile males the JC virus type 2 strain, subtype 2b, was more prevalent than ubiquitous type 1. JCV type 2 strain infection has been found to be associated with male infertility. These data suggest that the JC virus should be taken into consideration as an infectious agent which is responsible for male infertility.

Thirty years of research on infection and prostate cancer: no conclusive evidence for a link. A systematic review

BACKGROUND

The potential role of genitourinary infection in the etiology of prostate cancer (CaP) has been extensively investigated for 30 years. Two basic approaches have been used: tissue-based methods (polymerase chain reaction, immunohistochemistry, and in situ hybridization) and serologic assays (enzyme-linked immunosorbent assay, immunofluorescence, etc.). The objective of this review was to answer the question of whether infection of the male genitourinary tract may have a role in the etiology of CaP.

MATERIALS AND METHODS

We have carried out a systematic review of the evidence that was published in the MEDLINE/PubMed database until December 2011. The search terms included "prostate cancer," "infection," and the explicit names of the various infectious agents. Additional studies were identified using a reference search. A total of 74 papers were included in the review, which cover the following infectious agents: human papillomavirus, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, human herpesvirus, BK virus, JC virus, chlamydia, mycoplasma, ureaplasma, trichomonas, neisseria, treponema, Propionibacterium acnes, xenotropic murine leukemia virus-related virus and Candida albicans.

RESULTS

Despite the variable study designs and methodological approaches that were used, most of the pathogens that were studied were unlikely to be directly involved in prostate carcinogenesis.

CONCLUSIONS

The role of infection in the etiology of CaP has yet to be determined despite 30 years of research efforts. A discovery of an infectious agent that is associated with CaP would be of great medical importance; however, such a link would have to be firmly established before impacting on patient care.

Human polyomaviruses in skin diseases

Polyomaviruses are a family of small, nonenveloped viruses with a circular double-stranded DNA genome of ∼5,000 base pairs protected by an icosahedral protein structure. So far, members of this family have been identified in birds and mammals. Until 2006, BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40) were the only polyomaviruses known to circulate in the human population. Their occurrence in individuals was mainly confirmed by PCR and the presence of virus-specific antibodies. Using the same methods, lymphotropic polyomavirus, originally isolated in monkeys, was recently shown to be present in healthy individuals although with much lower incidence than BKV, JCV, and SV40. The use of advanced high-throughput sequencing and improved rolling circle amplification techniques have identified the novel human polyomaviruses KI, WU, Merkel cell polyomavirus, HPyV6, HPyV7, trichodysplasia spinulosa-associated polyomavirus, and HPyV9. The skin tropism of human polyomaviruses and their dermatopathologic potentials are the focus of this paper.

Association of autism with polyomavirus infection in postmortem brains

Autism is a highly heritable behavioral disorder. Yet, two decades of genetic investigation have unveiled extremely few cases that can be solely explained on the basis of de novo mutations or cytogenetic abnormalities. Vertical viral transmission represents a nongenetic mechanism of disease compatible with high parent-to-offspring transmission and with low rates of disease-specific genetic abnormalities. Vertically transmitted viruses should be found more frequently in the affected tissues of autistic individuals compared to controls. Our initial step was thus to assess by nested polymerase chain reaction (PCR) and DNA sequence analysis the presence of cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus type 1 (HSV1), herpes simplex virus type 2 (HSV2), human herpes virus 6 (HHV6), BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40) in genomic DNA extracted from postmortem temporocortical tissue (Brodmann areas 41/42) belonging to 15 autistic patients and 13 controls. BKV, JCV, and SV40 combined are significantly more frequent among autistic patients compared to controls (67% versus 23%, respectively; P < .05). The majority of positives yielded archetypal sequences, whereas six patients and two controls unveiled single-base pair changes in two or more sequenced clones. No association is present with the remaining viruses, which are found in relatively few individuals (N <or= 3). Also polyviral infections tend to occur more frequently in the brains of autistic patients compared to controls (40% versus 7.7%, respectively; P = .08). Follow-up studies exploring vertical viral transmission as a possible pathogenetic mechanism in autistic disorder should focus on, but not be limited to, the role of polyomaviruses.

BK virus and human cancer: innocent until proven guilty

BK virus (BKV) is a polyomavirus that ubiquitously infects the human population. Following a typically subclinical primary infection, BKV establishes a life-long persistent infection in the kidney and urinary tract. BKV is known to reactivate and cause severe disease in immunosuppressed patients, particularly renal and bone marrow transplant patients. Infection of BKV in rodent animal models or cells in culture often results in tumor formation or transformation, respectively. When co-expressed with activated oncogenes, BKV large tumor antigen drives the transformation of primary human cells. An etiological role of BKV in human cancer, however, remains controversial. Multiple reports have demonstrated conflicting results in regards to the presence of BKV sequences and/or proteins in various tumor types. This review compiles the most recent findings of BKV detection in a number of human cancers. Due to the lack of conclusive causality data from these studies, there does not appear to be a definitive association between BKV and human cancers.

The role of polyomaviruses in human disease

The human polyomaviruses, BK virus and JC virus, have long been associated with serious diseases including polyomavirus nephropathy and progressive multifocal leukoencephalopathy. Both viruses establish ubiquitous, persistent infections in healthy individuals. Reactivation can occur when the immune system is impaired, leading to disease progression. Recently, the human polyomavirus family has expanded with the identification of three new viruses (KI, WU and Merkel cell polyomavirus), all of which may prove to be involved in human disease. This review describes the general aspects of human polyomavirus infections and pathogenicity. Current topics of investigation and future directions in the field are also discussed.

Collecting duct carcinoma arising in association with BK nephropathy post-transplantation in a pediatric patient. A case report with immunohistochemical and in situ hybridization study

The development of malignancy in a renal transplant graft is an uncommon phenomenon. A renal neoplasm developing in the adult donor kidney of a pediatric transplant recipient has only rarely been reported. We report a case of collecting duct carcinoma arising in association with BK virus nephropathy in an adult living-related donor renal allograft to a pediatric recipient. Our case is the second report of neoplasia occurring in association with BK virus nephropathy post-transplantation, suggesting that BK virus may play a role in oncogenesis. It has been proposed that the T-Ag protein encoded by the polyomavirus family of viruses disrupts chromosomal integrity, creating oncogenes, and inactivating tumor suppressor genes. In our study, immunohistochemical staining with antibody directed against BK virus large T antigen showed nuclear staining within urothelium, tubular epithelium, tubular intraepithelial neoplasia, and invasive carcinoma. In situ hybridization did not identify BK virus DNA within neoplastic cells. T-Ag protein expression has been shown to be tumor-specific in bladder, gastric, and colorectal cancers. The finding of T-Ag protein expression in both intraepithelial and invasive neoplastic tissues in our case raises the possibility of BK virus as a causative agent in oncogenesis.

Low frequency of BK virus in prostatic adenocarcinomas

BK virus (BKV) exhibits many oncogenic properties and has been associated with a variety of tumors in humans. BKV has not been well studied in the context of prostate neoplasia; however, an association of BKV with prostatic adenocarcinoma has been suggested based on the detection of viral DNA sequences and expression of viral proteins in clinical samples. To further investigate the reported association of BKV with prostatic adenocarcinoma and the potential role of the virus in prostate tumorigenesis, 30 cases of adenocarcinoma of the prostate were analyzed for evidence of BKV infection by in situ hybridization and immunohistochemistry. In situ hybridization analysis detected BKV DNA in 2 of 30 (7%) prostatic adenocarcinomas, with positive signals focally identified in less than 1% of the neoplastic cells in both cases. However, none of the tumors evaluated demonstrated evidence of BKV large tumor antigen expression by immunohistochemistry. Among prostatic adenocarcinomas that showed no evidence of BKV infection, BKV DNA was focally observed in the adjacent non-neoplastic prostate tissue in four cases by in situ hybridization in the absence of BKV large tumor antigen immunoreactivity. The findings of the present study indicate rare cases of prostatic adenocarcinoma may be associated with BKV infection. However, lack of localization of BKV to a large population of the neoplastic cells and absence of BKV large tumor antigen expression suggest that the virus does not play a role in the pathogenesis of prostate cancer.

Discovery and epidemiology of the human polyomaviruses BK virus (BKV) and JC virus (JCV)

Although discovered over thirty years ago, many aspects of the epidemiology of BKV and JCV in the general population, such as the source of infectious virus and the mode of transmission, are still unknown. Primary infection with both BKV and JCV is usually asymptomatic, and so age seroprevalence studies have been used to indicate infection. BKV commonly infects young children in all parts of the world, with the exception of a few very isolated communities, adult seroprevalence rates of 65-90% being reached by the age of ten years. In contrast, the pattern of JCV infection appears to vary between populations; in some anti-JCV antibody is acquired early as for BKV, but in others anti-JCV antibody prevalence continues to rise throughout life. This indicates that the two viruses are probably transmitted independently and by different routes. Whilst BKV DNA is found infrequently in the urine of healthy adults, JCV viruria occurs universally, increasing with age, with adult prevalence rates often between 20% and 60%. Four antigenic subtypes have been described for BKV and eight genotypes are currently recognized for JCV. The latter have been used to trace population movements and to reconstruct the population history in various communities.

Polyomavirus in human cancer development

In animal studies, polyoma viruses have been found to be viral agents for oncogenesis and to produce a wide range of pathological lesions in experimental animals, including a variety of neoplastic tumors. The human polyoma viruses (JCV and BKV), along with their simian cousin (SV40), are ubiquitous viruses that are primarily associated with progressive multifocal leukoencephalolopathy (PML) and hemorrhagic cystitis, respectively, under specific conditions in immunocompromized individuals. Currently, polyoma viruses are now undergoing increasing scrutiny as possible causes for several human cancers. Evidence has been mounting recently that JCV, BKV as well as SV40 are potential oncogenic viruses in humans as well.

The pathobiology of polyomavirus infection in man

This article traces the discovery of polyomaviruses and outlines investigations, which shed light on potential modes of transmission of this increasingly important group of human pathogens. The pathobiology of the virus is summarized with particular reference to interactions with host cell receptors, cell entry, cytoplasmic trafficking, and targeting of the viral genome to the nucleus. This is followed by a discussion of sites of viral latency and factors leading to viral reactivation. Finally, we present biochemical mechanisms that could potentially explain several key elements of tissue pathology characteristic of BKV mediated damage to human kidney.

Kaposi's sarcoma-associated herpesvirus: clinical, diagnostic, and epidemiological aspects

Kaposi's sarcoma-associated herpesvirus (KSHI) is one of the few viruses proven to be associated with tumorigenesis in humans. Its causal association with all clinical and epidemiological variants of Kaposi's sarcoma (KS) is well established. KSHV is also involved in the pathogenesis of primary effusion lymphoma (PEL) and a subset of multicentric Castleman's disease (MCD). Possible associations of KSHV with other clinical settings have been extensively examined. The findings from several of these studies are contradictory and are yet to be resolved. Concentrated effort over the last decade, since the initial discovery of KSHV, led to the development of several experimental systems that resulted in a better comprehension of the biological characteristics of KSHV and set the stage for the understanding of mechainisms by which diseases are induced by the virus. The development of molecular, histological, and serological tools for KSHV diagnosis allowed researchers to track the transmission and to study the epidemiology of KSHV. These assays have been applied, in particular in ambiguous cases, in order to confirm clinically and pathologically based diagnoses. Here, we review the advances in the clinical, experimental, diagnostic, and epidemiological research of KSHV.

Human herpesvirus 6 activates lytic cycle replication of Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8) is a gamma-herpesvirus consistently identified in Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease. KSHV infection appears to be necessary, but not be sufficient for development of KS without other co-factors. However, factors that facilitate KSHV to cause KS have not been well defined. Because patients with KS are often immunosuppressed and susceptible to many infectious agents including human herpesvirus 6 (HHV-6), we investigated the potential of HHV-6 to influence the replication of KSHV. By co-culturing HHV-6-infected T cells with KSHV-latent BCBL-1 cell line, infecting BCBL-1 cells with HHV-6 virions, and generating heterokaryons between HHV-6-infected T cells and BCBL-1 cells, we showed that HHV-6 played a critical role in induction of KSHV replication, as determined by production of lytic phase mRNA transcripts and viral proteins. We confirmed and extended the results by using a luciferase reporter assay in which KSHV ORF50 promoter, the first promoter activated during KSHV replication, drove the luciferase expression. Besides HHV-6, we also found that cytokines such as interferon-gamma partially contributed to induction of KSHV replication in the co-culture system. These findings suggest that HHV-6 may participate in KS pathogenesis by promoting KSHV replication and increasing KSHV viral load.

Papilloma and polyoma DNA tumor virus sequences in female genital tumors

Human papillomaviruses (HPVs) and BKV, JCV, and SV40 polyomaviruses (PYVs) are oncogenic viruses associated with different human tumors. Our aim was to determine if PYV and HPV sequences could be detected in human genital tumors. HPV types 6b, 11, 16, and 18 and PYV were investigated in 22 genital tumor samples and the corresponding adjacent normal tissues, by PCR and filter hybridization. HPV and PYV sequences were also searched in six sperm fluid and four peripheral blood cell (PBC) samples. HPV-16 sequences were revealed in 7 of 14 cervical tumors and 1 of 1 vaginal adenocarcinoma, whereas 1 of 14 cervical carcinoma tested positive for HPV-18. Interestingly, each normal cervical tissue surrounding the neoplasm obtained from the same patient was positive for HPV type-16 and -18 with the same prevalence detected in tumors. BKV sequences were found in 9 of 14 cervical tumors, 1 of 7 vulvar tumors, and 1 of 1 adenocarcinoma, but also in normal tissues from cervix (13 of 14), vulva (6 of 7), sperm fluid (5 of 6) and PBC (3 of 4) samples. SV40 sequences were detected in 1 of 14 normal cervical tissue, 2 of 6 sperm fluids and 1 of 4 PBCs. None of the samples were JCV positive. To our knowledge, this is the first investigation reporting on the simultaneous association of both HPV and PYV with human genital tumors. These results suggest that PYV, together with HPV, may be involved as a cofactor in the onset/progression of human genital tumors, and raise the possibility that PYV act synergistically with HPV to enhance their pathogenicity in vivo. In addition, HPV and PYV may complement each other in infecting human genital tissues.

Detection and expression of human BK virus sequences in neoplastic prostate tissues

BK virus (BKV) is ubiquitous in the human population and establishes a lifelong, subclinical persistent infection in the urinary tract. When the immune system is compromised, it can cause severe disease in the kidney and bladder. Detection of BKV sequences in urinary tract neoplasms has led to the postulate that this virus may induce human oncogenesis through the function of its large tumor antigen (TAg). In this study, examination of prostate tumor tissue sections using in situ hybridization shows the presence of BKV sequences in atrophic epithelium. Solution polymerase chain reaction on DNA extracted from the tissues and sequence analysis of the products reveal the presence of BKV regulatory and early region sequences. In addition, immunohistochemical analysis using monoclonal antibodies specific to TAg or p53 shows the expression of TAg in some of the samples and p53 staining that can be correlated to TAg expression. Although the normal cellular localization of TAg and p53 is nuclear, double immunofluorescence labeling with anti-p53 and TAg antibodies indicates colocalization of p53 and TAg to the cytoplasm in the glandular epithelial cells of the sections. Although BKV DNA was found in benign and atrophic lesions, TAg and p53 coexpression was observed only in atrophic lesions.

Raf promotes human herpesvirus-8 (HHV-8/KSHV) infection

Human herpesvirus-8 (HHV-8/KSHV) is etiologically associated with Kaposi's sarcoma (KS) and other tumors. Constitutive activation of the mitogen-activated protein kinase (MAPK) signaling pathway has been associated with a variety of tumors, including AIDS-related KS. The oncoprotein Raf is situated at a pivotal position in regulating the MAPK pathway. Hence, we analysed the effect of oncoprotein Raf on HHV-8 infectious entry into target cells. Here we report Raf expression to significantly enhance HHV-8 infection of target cells. These findings implicate a role for Raf not only in the infectious entry of HHV-8 but also in modulating KS pathogenesis.

Oncogenic transformation by BK virus and association with human tumors

BK virus (BKV), a human polyomavirus closely related to JC virus and Simian Virus 40, is ubiquitous in human populations worldwide. After primary infection, BKV establishes a lifelong latent infection in many organs. BKV transforms rodent cells to the neoplastic phenotype and is highly oncogenic in rodents. This review considers the oncogenic potential of BKV in humans and its possible involvement in human tumors. BKV sequences and T antigen (Tag) are detected in several types of human neoplasms, although the viral load is generally low, with less than one copy of the viral genome per cell. The possible causative role of BKV in human oncogenesis rests on the ability of BKV Tag to inactivate the functions of tumor suppressor proteins p53 and pRB family as well as on its ability to induce chromosomal aberrations in human cells. A 'hit and run' mechanism and secretion of paracrine growth factors by BKV Tag-positive cells, recruiting into proliferation neighboring and distant cells, are discussed as possible BKV pathogenic elements in human oncogenesis.

Detection of human polyomaviruses and papillomaviruses in prostatic tissue reveals the prostate as a habitat for multiple viral infections

BACKGROUND

To determine whether human polyomavirus (hPy) genomes are present in prostate tissues, we have carried out a polymerase chain reaction (PCR) screening in two sets of prostate samples, archival and fresh frozen, as well as performing in situ hybridization (ISH). The frozen prostate samples as well as the urine from the same patients were also screened for human papillomavirus (HPV) sequences.

METHODS

Highly sensitive nested-PCR assays were used. The detection of subpopulations of JC virus (JCV) -transcriptional control regions (TCRs) was also evaluated by Southern analysis and by direct DNA sequencing. An in situ hybridization technique was also used to detect JCV DNA in prostatic tissue.

RESULTS

The paraffin-embedded archival samples gave variable, unsatisfactory results. Results from the fresh frozen samples, however, were consistent and were frequently positive for JCV and less frequent for BK virus DNA. ISH confirmed the presence of JCV DNA in prostatic glandular epithelium. The TCR region of JCV from prostate tissue and urine from prostate cancer patients showed the presence of both archetypal and rearranged TCRs, including several new sequence variants. HPV DNA was also frequently detected and in some cases also mixed with hPy DNA from frozen tissue and urine.

CONCLUSION

The use of fresh frozen samples proved to be essential for consistent and reproducible detection of HPV and hPy viral DNAs. The presence of JCV DNA by ISH and the occurrence of a subpopulation of JCV TCR regions suggests that the prostate is a site for virus replication. The prostate is a complex habitat where mixed infections with oncogenic DNA viruses frequently occur and opens the discussion to the potential role of these viruses in the cancer of the prostate.

Multiple sclerosis and Kaposi's sarcoma--chronic diseases associated with new human herpesviruses?

Two diseases that for many years have been suspected to be of viral origin are multiple sclerosis (MS) and Kaposi's sarcoma (KS). With the use of a new technique called representational difference analysis both these diseases have recently been associated with new lymphotropic herpesviruses, i.e. human herpesviruses (HHV) 6 and 8. HHV-6 is a ubiquitous virus and the etiological agent of exanthema subitum. Viral neuroinvasion occurs frequently in primary HHV-6 infection, and meningitis, encephalitis and demyelination have been described as rare complications. A relation with MS has been suggested for HHV-6, as the virus has been detected in MS plaques in the brain. Data from different studies are, however, conflicting and a definitive role for HHV-6 in MS pathogenesis has not been established. HHV-8 is believed to be the causative agent of KS, and is also associated with some rare hematological malignancies. The viral genome contains several potential oncogenes that are believed to have been picked up from the human genome during evolution. The role of HHV-8 in healthy, immunocompetent individuals is however uncertain. In conclusion, the full spectrum of human diseases associated with these new viruses is not yet understood, and rapid developments in molecular biology will continue to shed new light on the interactions between herpesviruses and their hosts.

Reactivation and role of HHV-8 in Kaposi's sarcoma initiation

Kaposi's sarcoma (KS) is an angioproliferative disease occurring in several clinical-epidemio-logic forms but all associated with infection by the human herpesvirus-8 (HHV-8). At least in early stages, KS is a reactive disease associated with a state of immune dysregulation characterized by CD8+ T-cell activation and production of Th1-type inflammatory cytokines (IC) that precedes lesion development. In fact, evidence indicates that IC can trigger lesion formation by inducing the activation of endothelial cells that leads to adhesion and tissue extravasation of lymphomonocytes, spindle cell formation, and angiogenesis, and HHV-8 reactivation that, in turn, leads to virus spread to all circulating cell types and virus dissemination into tissues. Due to virus escape mechanisms and deficient immune responses toward HHV-8, virus reactivation and spread are not controlled by the immune system but induce immune responses that may paradoxically exacerbate the reactive process. The virus is recruited into "activated" tissue sites where it finds an optimal environment for growth. In fact, viral load is very low in early lesions, whereas almost all spindle cells are infected in late-stage lesions. Although early KS is a reactive process of polyclonal nature that can regress, in time and in the presence of immunodeficiency, it can progress to a true sarcoma. This is likely due to the long-lasting expression of HHV-8 latency genes in spindle cells associated with the deregulated expression of oncogenes and oncosuppressor genes and, for AIDS-KS, with the effects of the HIV-1 Tat protein.

Human herpesvirus-8 and Kaposi's sarcoma: relationship with the multistep concept of tumorigenesis

Kaposi's sarcoma (KS) develops through discrete inflammatory-angiogenic stages of polyclonal nature (early-stage lesions) to monomorphic nodules of spindle-shaped cells that can be clonal (late-stage lesions) and resemble true sarcomas. Molecular and epidemiological studies indicate that development of KS is tightly associated with infection by the human herpesvirus-8 (HHV-8). However, only individuals with specific conditions of immunodysregulation develop KS. In these individuals the systemic and tissue increase of Th-1-type cytokines (IC) reactivate HHV-8 infection, leading to increased viral load, antibody titers, and an expanded cell tropism that precedes the clinical appearance of KS. Recruitment of the virus into tissues by infected monocytes and other cell types is facilitated by the endothelial cell activation due to IC. In clinical lesions, HHV-8 infection increases with lesion stage and in late-stage lesions most of the spindle cells are latently infected, whereas only few lyrically infected cells are present, suggesting that latent genes may have a role in the transformation of the early inflammatory-hyperplastic lesion into a real sarcoma. The development of tumors, however, is regulated through a multistep process based on the acquisition by cells of several different capabilities leading to malignant growth. Here we review the available data on the expression of HHV-8-encoded genes in primary KS lesions and, in view of their biological activity, analyze their potential function in different steps of tumorigenesis. By this pragmatic approach interesting insights into potential key functions of HHV-8-encoded genes are found and steps of potential cooperativity with other viral factors (HIV-1-Tat) in the pathogenesis of KS are identified.

Transcription pattern of human herpesvirus 8 open reading frame K3 in primary effusion lymphoma and Kaposi's sarcoma

Human herpesvirus 8 (HHV-8) is found in immunoblastic B cells of patients with multicentric Castleman's disease (MCD) and, predominantly in a latent form, in primary effusion lymphoma (PEL) cells and Kaposi's sarcoma (KS) spindle cells. Recent studies have shown that upon reactivation, HHV-8 expresses factors that downregulate major histocompatibility class I proteins and coactivation molecules and that may enable productively infected cells to escape cytotoxic T lymphocytes and natural killer cell responses. One of these viral factors is encoded by open reading frame (ORF) K3. Here we show that in PEL cells, ORF K3 is expressed through viral transcripts that are induced very early upon virus reactivation, including bicistronic RNA molecules containing coding sequences from viral ORFs K3 and 70. Specifically, we found that a bicistronic transcript was expressed in the absence of de novo protein synthesis, thereby identifying a novel HHV-8 immediate-early gene product. Several features of the RNA molecules encoding the K3 product, including multiple transcriptional start sites, multiple donor splicing sites, and potential alternative ATG usage, suggest that there exists a finely tuned modulation of ORF K3 expression. By contrast, ORF K3 transcripts are not detected in the majority of cells present in KS lesions that are latently infected by the virus, suggesting that there are other, as-yet-unknown mechanisms of immune evasion for infected KS spindle cells. Nevertheless, because HHV-8 viremia precedes the development of KS lesions and is associated with the recrudescence of MCD symptoms, the prompt expression of ORF K3 in productively infected circulating cells may be important for virus pathogenesis. Thus, molecules targeting host or viral factors that activate ORF K3 expression or inactivate the biological functions of the K3 product should be exploited for the prevention or treatment of HHV-8-associated diseases in at-risk individuals.

Bk virus: a clinical review

We present a review of the clinically oriented literature about BK virus, a relative of JC virus, which is the etiologic agent of progressive multifocal leukoencephalopathy (PML). The kidney, lung, eye, liver, and brain have been proposed as sites of BK virus-associated disease, both primary and reactivated. BK virus has also been detected in tissue specimens from a variety of neoplasms. We believe that BK virus is most often permissively present in sites of disease in immunosuppressed patients, rather than being an etiologic agent that causes symptoms or pathologic findings. There is, however, strong evidence for BK virus-associated hemorrhagic cystitis and nephritis, especially in recipients of solid organ or bone marrow transplants. Now that BK virus can be identified by use of specific and sensitive techniques, careful evaluation of the clinical and pathologic presentations of patients with BK virus will allow us to form a clearer picture of viral-associated pathophysiology in many organ systems.

Biology of Kaposi's sarcoma

Kaposi's sarcoma (KS) is an angioproliferative disease occurring in several different clinical-epidemiological forms that, however, share the same histological traits and are all associated with infection by the human herpesvirus 8 (HHV8). KS initiates in a context of immune dysregulation characterised by CD8+ T cell activation and the production of Th1-type cytokines that induce a generalised activation of endothelial cells leading to adhesion and tissue extravasation of lympho-monocytes, spindle cell formation and angiogenesis. These phenomena are triggered or enhanced by infection with HHV8 that, in turn, is reactivated by the same cytokines. Productively-infected circulating cells are recruited into 'activated' tissue sites where HHV8 finds an optimal environment for establishing a persistent, latent infection of KS spindle cells (KSC). HHV8 dissemination is favoured by virus escape mechanisms and immune dysregulation, and leads to immune responses that are not effective against the virus but, paradoxically, exacerbates the reactive process. Although early KS is a reactive process of polyclonal nature that can regress, in time it can progress in to a true sarcoma. The progression of KS appears to be due to the deregulated expression of oncogenes and oncosuppressor genes, to the long-lasting expression of the HHV8 latency genes and, for AIDS-KS, is promoted by the proliferative and angiogenic effects of the HIV-1 Tat protein.

Viruses in the mammalian male genital tract and their effects on the reproductive system

This review describes the various viruses identified in the semen and reproductive tracts of mammals (including humans), their distribution in tissues and fluids, their possible cell targets, and the functional consequences of their infectivity on the reproductive and endocrine systems. The consequences of these viral infections on the reproductive tract and semen can be extremely serious in terms of organ integrity, development of pathological and cancerous processes, and transmission of diseases. Furthermore, of essential importance is the fact that viral infection of the testicular cells may result not only in changes in testicular function, a serious risk for the fertility and general health of the individual (such as a fall in testosteronemia leading to cachexia), but also in the possible transmission of virus-induced mutations to subsequent generations. In addition to providing an exhaustive account of the data available in these domains, this review focuses attention on the fact that the interface between endocrinology and virology has so far been poorly explored, particularly when major health, social and economical problems are posed. Our conclusions highlight the research strategies that need to be developed. Progress in all these domains is essential for the development of new treatment strategies to eradicate viruses and to correct the virus-induced dysfunction of the endocrine system.

Epidemiology and pathogenesis of Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma (KS) occurs in Europe and the Mediterranean countries (classic KS) and Africa (endemic KS), immunosuppressed patients (iatrogenic or post-transplant KS) and those with acquired immune deficiency syndrome (AIDS), especially among those who acquired human immunodeficiency virus sexually (AIDS-KS). KS-associated herpesvirus (KSHV or HHV-8) is unusual among herpesviruses in having a restricted geographical distribution. Like KS, which it induces in immunosuppressed or elderly people, the virus is prevalent in Africa, in Mediterranean countries, among Jews and Arabs and certain Amerindians. Distinct KSHV genotypes occur in different parts of the world, but have not been identified as having a differential pathogenesis. KSHV is aetiologically linked to three distinct neoplasms: (i) KS, (ii) primary effusion lymphoma, and (iii) plasmablastic multicentric Castleman's disease. The histogenesis, clonality and pathology of the tumours are described, together with the epidemiology and possible modes of transmission of the virus.

Activation of Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) lytic replication by human cytomegalovirus

The majority of Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells identified in vivo contain latent KSHV, with lytic replication in only a few percent of cells, as is the case for the cells of Kaposi's sarcoma (KS) lesions. Factors that influence KSHV latent or lytic replication are not well defined. Because persons with KS are often immunosuppressed and susceptible to many infectious agents, including human cytomegalovirus (HCMV), we have investigated the potential for HCMV to influence the replication of KSHV. Important to this work was the construction of a recombinant KSHV, rKSHV.152, expressing the green fluorescent protein (GFP) and neo (conferring resistance to G418). The expression of GFP was a marker of KSHV infection in cells of both epithelial and endothelial origin. The rKSHV.152 virus was used to establish cells, including human fibroblasts (HF), containing only latent KSHV, as demonstrated by latency-associated nuclear antigen expression and Gardella gel analysis. HCMV infection of KSHV latently infected HF activated KSHV lytic replication with the production of infectious KSHV. Dual-color immunofluorescence detected both the KSHV lytic open reading frame 59 protein and the HCMV glycoprotein B in coinfected cells, and UV-inactivated HCMV did not activate the production of infectious KSHV-GFP. In addition, HCMV coinfection increased the production of KSHV from endothelial cells and activated lytic cycle gene expression in keratinocytes. These data demonstrate that HCMV can activate KSHV lytic replication and suggest that HCMV could influence KSHV pathogenesis.

Role of viral agents in the pathogenesis of Kaposi's sarcoma

Several viruses have been detected, at various frequencies, in Kaposi's sarcoma (KS) tissues. The detection of human herpesvirus 8 (HHV-8) in all the epidemiological and histological forms of KS makes it the most attractive candidate causative agent to date. In this report, we discuss the possible explanations for the detection of genomic sequences of various viral agents in KS and the putative role of those viruses in the pathogenesis of the disease.

Human herpesvirus 8: is it a tumor virus?

Human herpesvirus 8 (HHV-8), also termed Kaposi's sarcoma-associated herpesvirus, was identified in Kaposi's sarcoma (KS) biopsy specimens in 1994. The epidemiological data available to date indicate a strong association of HHV-8 with KS. It appears that HHV-8 is necessary for KS development. HHV-8 DNA is invariably found in all epidemiological forms of KS and primary effusion lymphomas. In contrast, HHV-8 DNA is rarely found in various tumor and nontumor tissues from patient groups not at risk of KS. Although current serology does not allow us to assess the HHV-8 prevalence in the general population, high titers of HHV-8 antibodies are almost exclusively found in KS risk groups. In addition, HHV-8 seroconversion has been shown to precede KS development. The mechanisms and genes involved in HHV-8 pathogenesis are less clear. HHV-8 belongs to a family of transforming viruses, and several candidate oncogenes have been identified by using rodent fibroblast transformation assays. However, expression of most of these genes could not be shown in latently infected tumor cells. As the HHV-8 genome encodes several cytokines and cytokine receptor homologues, HHV-8 may also promote KS pathogenesis through paraendocrine mechanisms.

Multiplex polymerase chain reaction for the simultaneous detection and typing of polyomavirus JC, BK and SV40 DNA in clinical samples

A novel multiplex nested PCR (nPCR) method was developed for detecting and differentiating simultaneously the DNA of polyomaviruses JC, BK and SV40 in a single tube. In the first amplification step the same set of primers were used to amplify a conserved DNA region of the large T antigen gene of JCV, BKV and SV40. The second round of multiplex nPCR was carried out using a set of primers designed to render products of different size for each related virus. The thermocycling parameters and concentration of each reaction component were optimised systematically to achieve optimal specificity and sensitivity for the nPCR assay. The sensitivity of the method ranged between one and 10 copies of polyomavirus genome. Cerebrospinal fluid (CSF) was examined from AIDS patients with clinical and neuroradiological evidence of progressive multifocal leukoencephalopathy (PML) and CSF from AIDS patients with other neurological alterations. Urine specimens from bone marrow transplant recipients affected by haemorrhagic cystitis were also tested. The results obtained suggest that the assay is a good tool for supporting the diagnosis of polyomavirus infection and could be used for epidemiological purposes and in other studies in order to define better the role of polyomaviruses in human disease.

Penile intraepithelial neoplasia overlying Kaposi's sarcoma lesions: role of viral synergy?

Several viral agents have been detected in the lesional tissue of Kaposi's sarcoma (KS). Their precise oncogenic role remains to be determined. A 32-year-old heterosexual man with acquired immunodeficiency syndrome (AIDS) who had penile lesions of KS with overlying epithelial changes characteristic of intraepithelial neoplasia associated with concurrent infection by human papillomavirus (HPV) and human herpesvirus 8 (HHV-8) is reported. The absence of viral DNA from uninvolved skin suggests that this coinfection is more than coincidental and may involve synergy between these viruses, as has already been suggested for HPV and herpes simplex 2 virus.

JC virus DNA is present in the mucosa of the human colon and in colorectal cancers

JC virus (JCV) is a polyoma virus that commonly infects humans. We have found T antigen DNA sequences of JCV in the mucosa of normal human colons, colorectal cancers, colorectal cancer xenografts raised in nude mice, and in the human colon cancer cell line SW480. A larger number of viral copies is present in cancer cells than in non-neoplastic colon cells, and sequence microheterogeneity occurs within individual colonic mucosal specimens. The improved yield of detection after treatment with topoisomerase I suggests that the viral DNA is negatively supercoiled in the human tissues. These results indicate that JCV DNA can be found in colonic tissues, which raises the possibility that this virus may play a role in the chromosomal instability observed in colorectal carcinogenesis.

The role of HHV-8 in Kaposi's sarcoma

The epidemiology of Kaposi's sarcoma (KS) amongst North American and Northern European patients with AIDS suggests that an infectious agent other than HIV is involved in its pathogenesis. Several lines of evidence indicate that human herpesvirus 8 (HHV-8), also termed Kaposi's sarcoma associated herpesvirus, is the sought after agent. DNA of HHV-8 is invariably found in all forms of KS where the virus is present in the KS spindle cell. In contrast, HHV-8 DNA is not regularly detected in most other malignancies. Antibodies against HHV-8 are more frequently found in groups at risk of KS, and HHV-8 seroconversion precedes KS development. Several HHV-8 genes have been identified that exhibit transforming potential in cell culture systems. In addition, the virus encodes and induces several cytokines and angiogenic factors. This is of particular interest as models of KS pathogenesis developed before the discovery of HHV-8 emphasized the importance of inflammatory cytokines. Although the expression pattern of viral genes in KS is not certain yet, it appears likely that the pathogenetic role of HHV-8 in KS may be rather complex and differs from other virus-induced malignancies. 1999 Academic Press.

In vitro sensitivity of Kaposi's sarcoma cells to various chemotherapeutic agents including acyclic nucleoside phosphonates

The involvement of a viral agent in the pathogenesis of Kaposi's sarcoma (KS) points to antiviral agents as possible therapeutic and/or prophylactic options in the management of the disease. In the present study we investigated the antiproliferative effects of various chemotherapeutic agents, including acyclic nucleoside phosphonates, on the growth of KS-derived cells. Nested PCR amplification demonstrated that these cells do not contain human herpesvirus 8 (HHV-8) DNA sequences. The cytotoxicity of the chemotherapeutic compounds was less pronounced in KS cells than in human dermal microvascular endothelial cells, which are considered to be the normal counterpart of KS cells. Stimulation of KS cells with basic fibroblast growth factor (bFGF) and correction of the IC50 values by the doubling times revealed that the apparent chemotherapeutic resistance of KS cells could mainly be attributed to the long doubling times of these cells. bFGF-stimulated KS cells still exhibited no particular sensitivity to the acyclic nucleoside phosphonates whose activity extends to HHV-8, which is consistent with the absence of linear HHV-8 DNA synthesis in these cells. Our data suggest that neither anti-cancer agents nor antiviral agents such as the acyclic nucleoside phosphonates can discriminate efficiently between KS cells and normal endothelial cells.

Morphological, histochemical, immunohistochemical, and ultrastructural characterization of tumors and dysplastic and non-neoplastic lesions arising in BK virus/tat transgenic mice

To study the role in AIDS pathogenesis of the human immunodeficiency virus type 1 (HIV-1) Tat protein, a transactivator of viral and cellular genes, we generated transgenic mice with a recombinant DNA containing BK virus (BKV) early region and the HIV-1 tat gene, directed by its own promoter-enhancer. DNA hybridization revealed that the transgene is stably maintained in all organs of transgenic mice as a tandem insertion in a number of copies ranging from 5 to 20 per cell. In addition, tat and BKV RNA were expressed in all tissues. Transgenic mice developed three types of lesions: 1) tumors, 2) hyperplastic and dysplastic lesions, and 3) non-neoplastic lesions. Tumors of different histotypes, such as lymphomas, adenocarcinomas of skin glands, leiomyosarcomas, skin squamous cell carcinomas, hepatomas, hepatocarcinomas, and cavernous liver hemangiomas, developed in 29% of transgenic animals. The majority of tumors were malignant, invasive, and producing metastases. Conversely, tumors of only two histotypes (lymphomas and adenocarcinomas of skin glands) appeared in control mice. Hyperplastic and dysplastic lesions were more frequent in transgenic than in control mice and involved the skin or its adnexes, the liver and the rectum, indicating multiple targets for the activity of the transgene. Pyelonephritis, frequently complicated with hydronephrosis, inflammatory eye lesions, and amyloid depositions represented the most frequent non-neoplastic lesions detected in transgenic mice. Many of the pathological findings observed in this animal model are comparable to similar lesions appearing in AIDS patients, suggesting a relevant role for Tat in the pathogenesis of such lesions during the course of AIDS.