Parvovirus B19 is associated with benign testes as well as testicular germ cell tumours

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.

Role of Viral Infections in Testicular Cancer Etiology: Evidence From a Systematic Review and Meta-Analysis

The most represented histotype of testicular cancer is the testicular germ-cell tumor (TGCT), both seminoma and non-seminoma. The pathogenesis of this cancer is poorly known. A possible causal relationship between viral infections and TGCTs was firstly evoked almost 40 years ago and is still a subject of debate. In the recent past, different authors have argued about a possible role of specific viruses in the development of TGCTs including human papillomavirus (HPV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), Parvovirus B-19, and human immunodeficiency virus (HIV). The aim of this present review was to summarize, for each virus considered, the available evidence on the impact of viral infections on the risk of developing TGCTs. The review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included all observational studies reported in English evaluating the correlations between viral infections (HPV, CMV, EBV, Parvovirus B19, and HIV) and TGCTs. The methodological quality of studies included in the meta-analysis was evaluated using a modified version of the "Newcastle-Ottawa Scale." Meta-analyses were conducted using the "Generic inverse variance" method, where a pooled odds ratio (OR) was determined from the natural logarithm (LN) of the studies' individual OR [LN (OR)] and the 95% CI. A total of 20 studies (on 265,057 patients) were included in the review. Meta-analysis showed an association with TGCTs only for some of the explored viruses. In particular, no association was found for HPV, CMV, and Parvovirus B-19 infection (p = ns). Conversely, EBV and HIV infections were significantly associated with higher risk of developing TGCTs (OR 7.38, 95% CI 1.89-28.75, p = 0.004; OR 1.71, 95% CI 1.51-1.93, p < 0.00001). In conclusion, we found adequate evidence supporting an oncogenic effect of HIV and EBV on the human testis. Conversely, available data on HPV and TGCTs risk are conflicting and further studies are needed to draw firm conclusions. Finally, current evidence does not support an effect of CMV and Parvovirus B-19 on testicular carcinogenesis.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

No evidence of persistent parvovirus B19 viremia among Iranian patients with HIV after a 1-year follow-up

Recent studies have demonstrated that, in common with other latent viruses, parvovirus B19 infection can be controlled by the host immune response but may persist in some places such as the bone marrow. Persistent B19 infection has been found in both immunocompetent and immunocompromised individuals, such as patients infected with human immunodeficiency virus (HIV). However, there is limited data regarding long-term B19 viremia in HIV patients. In this study, we investigated virological and hematological findings, and also the clinical outcome, of seven cases of HIV/B19 coinfection (confirmed by PCR) after one year. These cases were provided from a previous study on patients with HIV infection that found B19 DNA in 13 cases. Seven of these 13 patients were available after 1 year, and we retested them for B19 viremia and B19-specific antibodies. B19 IgG was tested by ELISA, and B19 DNA was assessed by nested PCR. Anemia was not observed in these cases. All subjects had cleared viremia, but B19 IgG seroconversion occurred in two cases. No significant changes in CD4 and hemoglobin occurred. The results of this study indicate that B19 infection in HIV patients is a subtle infection and that B19 viremia is not a long-term event.

Parvovirus b19 persistence in abnormal thyroid tissue of a mature cystic ovarian teratoma: a case report

Ovarian teratomas represent the most common neoplasm derived from germ cells and can contain mature ectodermal, mesodermal, and endodermal tissues. In rare cases, these teratomas can be composed predominantly or solely of thyroid tissue. These thyroid cells often function similarly to normal thyroid tissues. This laboratory and others have previously shown that parvovirus B19 (B19V) persists in primary and metastatic thyroid tissues. No reports exist on possible B19V persistence in thyroid tissues that may arise de novo outside the thyroid gland proper. In this case report, the detection of B19V (genotype 1) in the thyroid epithelial cells of a mature teratoma is reported. Nested PCR and immunohistochemistry were used to detect viral nucleic acids and proteins, respectively. Viral genomes were amplified in lesion DNA, confirming persistence of B19V. Positive immunohistochemical staining was seen for B19V capsid proteins in the thyroid epithelial cells within the mature teratoma, but not in surrounding ovarian tissue or in the non-thyroidal elements of the mature teratoma. These results demonstrate for the first time that thyroid epithelial cells, derived from non-thyroid tissue, are capable of supporting B19V infection and persistence.

Parvovirus B19 infection in Hashimoto's thyroiditis, papillary thyroid carcinoma, and anaplastic thyroid carcinoma

BACKGROUND

The human pathogenic parvovirus B19 (B19) has recently been detected in papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis (HT) tissues at a high frequency in two studies of a Chinese cohort. We wanted to extend these data to include another cohort and expand the thyroid tumor tissue types assessed. In particular, we were interested to find whether B19 also infects anaplastic thyroid carcinoma (ATC), one of the most aggressive human cancers.

METHODS

Commercially available thyroid tumor tissue arrays were used to detect B19 capsid protein by immunohistochemistry in various types of thyroid tumors and disorders. The arrays were representative of the four main types of thyroid tumors, as well as other thyroid autoimmune disorders such as HT and Graves' disease, and adenomas, goiters, lymphomas, and normal thyroid tissue. In total, at least 12 different types of thyroid conditions as well as normal tissue were represented, many with multiple subjects.

RESULTS

Twenty-one of the 24 (88%) PTC tumors, 3 of the 3 ATC/undifferentiated tumors, and 3 of the 3 HT tissue samples were positive for B19 capsid protein by immunohistochemistry. The localization of the protein differed based on pathological disease type, with a nuclear to cytoplasmic shift seen from unaffected to tumor tissue.

CONCLUSIONS

We extend the data available on B19 detection in the thyroid to show a high correlation of virus in another cohort of PTC and HT at the protein level. We also show, for the first time, B19 infection of much more highly aggressive ATC/undifferentiated tumors. Nuclear to cytoplasmic shift in B19 protein in cancer tissue suggests a possible link between B19 and thyroid cancer pathogenesis/progression.

Tissue persistence and prevalence of B19 virus types 1–3

Human parvovirus B19 is a minute ssDNA virus that causes a wide variety of diseases, including erythema infectiosum, arthropathy, anemias and fetal death. In addition to the B19 prototype, two new variants (B19 types 2 and 3) have been identified. After primary infection, B19 genomic DNA has been shown to persist in solid tissues of not only symptomatic but also of constitutionally healthy, immunocompetent individuals. The viral DNA persists as an intact molecule without persistence-specific mutations, and via a storage mechanism with life-long capacity. Thus, the mere presence of B19 DNA in tissue cannot be used as a diagnostic criterion, although a possible role in the pathology of diseases, for example through mRNA or protein production, cannot be excluded. The molecular mechanism, host-cell type and possible clinical significance of tissue persistence are yet to be elucidated.

Detection of parvovirus B19 DNA in the lesional skin of patients with Behçet's disease

BACKGROUND

There is disagreement in the current evidence for viral aetiologies in the pathogenesis of Behçet's disease (BD).

OBJECTIVES

To investigate the presence of B19 DNA in skin lesions of patients with BD, compare with the skin of healthy controls and evaluate its role in the pathogenesis.

METHODS

In total, 40 patients diagnosed with BD according to the criteria proposed by the International Study Group for Behçet's Disease and routinely followed up at our centre were enrolled into the study. All the patients selected were in the active phase of disease. Skin and blood samples of patients with BD and of the healthy volunteers were examined for B19 serology, histopathology and genome expression.

RESULTS

The quantity of B19 DNA in nonulcerative BD lesions of was significantly different from ulcerative lesions in the study group and from the skin of the healthy controls (P < 0.01). For the nonulcerative lesions, real-time PCR analysis for B19 DNA was found to be 64% sensitive (95% CI 42.5-82.0) and 85% specific (95% CI 62.1-96.6) with a cut-off value of > 154 IU/mL (P < 0.001).

CONCLUSIONS

To the best of our knowledge, this is the first study that provides evidence for a possible causal link between BD and parvovirus B19, and our data suggest the presence of the virus, particularly in intact, nonulcerative skin lesions of BD. Limitations to this study include the limited number of participants, and the fact that the exact source of B19 DNA was undetected.

Parvovirus B19: the causative agent of dilated cardiomyopathy or a harmless passenger of the human myocard?

Parvovirus B19 infections may cause a widespread benign and self-limiting disease in children and adults known as erythema infectiosum (fifth disease). Several further manifestations are associated with B19 infections, such as arthralgias, arthritis, leucopenia and thrombocytopenia, anaemia and vasculitis and spontaneous abortion and hydrops fetalis in pregnant women. Persistent infections with continuous virus production may occur in immunocompetent as well as in immunosuppressed individuals. Parvovirus B19 infections have been frequently implicated as a cause or trigger of various forms of autoimmune diseases affecting joints, connective tissue and large and small vessels. Autoimmune neutropenia, thrombocytopenia and haemolytic anaemia are known as sequelae of B19 infections. The molecular basis of the autoimmune phenomena is unclear. Many patients with these long-lasting symptoms are not capable of eliminating the virus or controlling its propagation. Furthermore, latent viral genomes have been detected in cells of various organs and tissues by PCR. At present, it is not clear if these cells produce viral proteins and/or infectious B19 particles, if the virus genome can be reactivated to productive replication and if the presence of viral DNA indicates a causative role of parvovirus B19 with distinct diseases.

Pathogenesis of Parvovirus B19 Infection: Host Gene Variability, and Possible Means and Effects of Virus Persistence

Since conducting follow-up studies of patients with acute symptomatic parvovirus B19 infection which showed that a significant proportion of patients develop prolonged arthritis and chronic fatigue syndrome (CFS), we have become interested in the mechanisms of this phenomenon. We showed that these cases have high levels of pro-inflammatory cytokines in their circulation and that this correlates with the symptoms. However, the underlying mechanisms were not apparent, and we have used various approaches to begin studying this phenomenon. DNA polymorphisms were looked for and several were shown to be more common in these subjects compared with controls; these occur within genes of both the immune response [human leucocyte antigen (HLA)-DRB1, HLA-B, transforming growth factor (TGF)-beta1] and those involved in several other cellular functions (predominantly the cytoskeleton and cell adhesion). Interestingly, one particular single-nucleotide polymorphism (SNP) which is associated with symptomatic B19 infection occurs in the Ku80 gene which has recently been shown to be a B19 co-receptor. B19 persistence is probably the key to this phenomenon, and some new data are presented on short regions of sequence homology (17-26 bp) between human, mouse and rat parvoviruses and their respective hosts which occur in many host genes. This homology may provide a foothold for virus persistence and may also play a role in the genesis of disease through gene disruption. Finally, we used microarrays and TaqMan real-time polymerase chain reaction in 108 normal persons to study human gene expression in persons who are B19-seropositive versus B19-seronegative (age- and sex-matched) to examine the hypothesis that gene regulation may be altered in subjects harbouring the B19 virus DNA. Six genes were found to be differentially expressed with roles in the cytoskeleton (SKIP, MACF1, SPAG7, FLOT1), integrin signalling (FLOT1, RASSF5), HLA class III (c6orf48), and tumour suppression (RASSF5). These results have implications not only for B19 but also for other persistent viruses as well and confirmation is required. In conclusion, these disparate findings contribute to our understanding of the pathogenesis of B19 disease. We are using these studies as a starting point to study the phenomenon of chronic immune activation following B19 infection.

Update on non-acquired immunodeficiency syndrome-defining malignancies

PURPOSE OF REVIEW

Since the introduction of highly active antiretroviral therapy (HAART), the natural history of human immunodeficiency virus (HIV) infection has changed. Early in the acquired immunodeficiency syndrome (AIDS) epidemic, epidemiologic studies showed that HIV-infected patients were at higher risk for developing specific AIDS-defining malignancies. More recent studies linking HIV/AIDS databases to cancer registries have shown that HIV-infected patients are also at higher risk of developing non-AIDS-defining malignancies. We review the most recent data regarding clinical presentation, pathology, and treatment outcomes for these non-AIDS-defining malignancies.

RECENT FINDINGS

Recent large cohort studies linking HIV/AIDS databases to cancer registries have shown that HIV-infected patients are also at higher risk of developing non-AIDS-defining malignancies. Besides anal cancer and Hodgkin disease, the cohort studies have identified other malignancies that appear to occur at a higher rate in the HIV-infected population as compared with the general population. These malignancies include lung cancer, skin cancer, germ cell tumors, leiomyosarcomas, cancers of the head and neck, conjunctival cancer, multiple myeloma, and leukemias.

SUMMARY

As the epidemiology of non-AIDS-defining malignancies continues to evolve, it is unclear whether the appropriate treatments and outcomes for these or other malignancies are changed for HIV-infected patients treated with HAART.

Neurological manifestations of human parvovirus B19 infection

Since its discovery, human parvovirus B19 has been linked with a broad spectrum of clinical syndromes. An aetiological role for the virus has been confirmed in erythema infectiosum, transient aplastic crisis, persistent infection manifesting as pure red cell aplasia in immunocompromised persons, non-immune hydrops fetalis and arthritis. Less commonly recognised, but receiving increasing attention recently, are the neurological manifestations, a variety of which have been described in patients with either clinically diagnosed or laboratory confirmed B19 infection. The purpose of this review is to summarise present knowledge of B19, its known and potential pathogenic mechanisms and its association with human diseases, particularly those with neurological manifestations. The outcome of the review supports an aetiological role of the virus in neurological disease. However, the pathogenesis remains unknown and elucidating this is a priority.

No association between human parvovirus B19 and testicular germ cell cancer

The incidence of testicular germ cell cancer, which is the most common cancer among young male adults, is increasing. The aetiology remains unknown, although a virus has been proposed. A previous study has shown a high prevalence of human parvovirus B19 (B19) DNA in the testes of patients with testicular germ cell tumours (85%) and suggested that B19 may play a role in tumour development. To address this question of causality, seroreactivity to B19 was studied among cases (n=80) and controls (n=241) using serum samples drawn before the onset of disease, in addition to an elucidation of the frequency of virus DNA in a retrospectively collected 2-year testicular carcinoma series. No association was found between B19 seropositivity and the risk of testicular cancer (odds ratio=1.03; 95% confidence interval=0.60-1.77) nor was there any dose-response relation (P for trend=0.53). This study did, however, confirm the observation that B19 DNA can be detected in testicular carcinoma tissue, as 4 of 24 cases were found to be positive, while no B19 DNA could be detected in the control cases. It is speculated that this finding may be due to susceptibility of the carcinoma cells to B19 virus owing to high-level expression of the viral receptor glycosphingolipid (Gb4) and possible other putative cellular factors resulting in a localized persistence initiated after the development of cancer.

Persistence of human parvovirus B19 in human tissues

Human parvovirus B19 infection causes various clinical symptoms, such as rash, arthropathy, anemias and fetal death, but it can also remain asymptomatic. The arthropathies and anemias can become chronic for several years, not infrequently resembling autoimmune syndromes. B19 replicates only in red blood cell precursors of bone marrow or fetal liver, resulting in high-titred short-lived viremia, but viral DNA is detectable also in cells of several other types. Recently B19 DNA has been found, by very sensitive amplification tests, in certain tissues not only of symptomatic but also of healthy individuals for several years or decades after B19 infection. The mere presence of B19 DNA in these tissues of a symptomatic patient (e.g. joints in chronic arthritis or skin in dermatomyositis) thereby does not prove that the present disease is caused by B19. The diagnosis has to be verified by other innovative means. How and why viral DNA persists in the tissues of healthy individuals is under investigation.

Germ cell tumors in patients infected by the human immunodeficiency virus

BACKGROUND

The objective of this study was to assess the natural history of the two disease courses, patient immune system tolerance, and results of therapy in human immunodeficiency virus (HIV)-infected patients with germ cell tumors (GCT).

METHODS

From 1985 to 1996, 34 HIV-infected men received a diagnosis of GCT. Their charts were analyzed retrospectively.

RESULTS

Sixteen patients had seminomas, and 18 had nonseminomatous GCTs (NSGCT); 71% had International Union Against Cancer (UICC), 1997 Stage I-II GCTs. At the time of chemotherapy, 69%, 6%, and 25% of patients with advanced NSGCT were in the International Germ Cell Consensus Classification (IGCCC) good, intermediate, and poor prognostic group, respectively. All except 1 of the 10 patients with advanced seminomas were in the IGCCC good prognostic group. At diagnosis of GCT, 85% of patients were classified as having asymptomatic HIV infection or only persistent generalized lymphadenectomy. The median CD4 cell count was 325/microL (range, 6-1125). Overall, 26 patients were given chemotherapy, but the planned dose intensity was respected in only 15 (57%) patients. Severe toxic effects included febrile neutropenia in 35% of patients. During chemotherapy, zidovudine, prophylactic granulocyte colony-stimulating factor (G-CSF), and a Pneumocystis carinii prophylaxis were given in 19%, 23%, and 35% of cases, respectively. CD4 cell count decreased in 7 (64%) of 11 patients during chemotherapy. Infradiaphragmatic radiotherapy was given in 10 cases and was clinically well tolerated. At a median follow-up of 27 months (range, 3-150), 50% of patients were alive, and only 18% of patients died of GCT. Two patients developed a non-GCT malignancy while in complete remission, namely, Hodgkin disease and an acute leukemia.

CONCLUSIONS

The prognosis of GCT in HIV-infected patients is mostly dictated by the HIV infection. Patients should be treated according to stage and histologic subtype, although dose reduction of chemotherapy might be necessary in approximately half of the patients. Close surveillance of neutrophil and CD4 cells counts, as well as the use of G-CSF and systematic anti-Pneumocystis carinii prophylaxis are recommended during chemotherapy. The use of highly active antiretroviral therapy during chemotherapy for GCT requires a prospective assessment.