Localization of Epstein-Barr virus to infiltrating lymphocytes in breast carcinomas and not malignant cells

Detection of a large spectrum of viral infections in conjunctival premalignant and malignant lesions

To study the interaction between HIV and other carcinogenic infections in conjunctival squamous cell carcinoma (SCC), we evaluated the presence of a broad spectrum of human viruses in conjunctiva specimens. Beta Human papillomavirus (HPV; n = 46), gamma HPV (n = 52), polyomaviruses (n = 12) and herpes viruses (n = 3) was determined in DNA extracted from 67 neoplastic and 55 non-neoplastic conjunctival tissues of HIV-positive and HIV negative subjects by Luminex-based assays. Next-generation sequencing (NGS) was also used to further characterize the presence of cutaneous HPVs. Detection of beta-2 HPV infections was associated with the risk of neoplasia (adjusted odds ratio [aOR] 3.0; 95% confidence interval [CI] 1.3-6.8), regardless of HIV status (HIV positive, aOR 2.6, 95% CI 0.9-7.7; HIV negative, aOR 3.5, 95% CI 0.9-14.4). EBV was strongly associated with the risk of neoplasia (aOR 12.0, 95% CI 4.3-33.5; P < .01) mainly in HIV individuals (HIV positive, aOR 57.5; 95% CI: 10.1-327.1; HIV negative aOR 2.6; 95% CI: 0.2-34.7). NGS allowed to identify 13 putative novel HPVs in cases and controls. Our findings suggest a role of beta HPV types and EBV, in conjunctival SCC. However, additional studies of viral expression in tumor tissue are required to confirm the causal association.

Epstein-Barr Virus Infection and Increased Sporadic Breast Carcinoma Risk: A Meta-Analysis

OBJECTIVE

An association of Epstein-Barr virus (EBV) infection with breast carcinoma (BC) risk has so far been disputed in the literature. Therefore, we performed a meta-analysis to clarify this relationship.

MATERIALS AND METHODS

An electronic database search for eligible case-control studies was performed using PubMed, Embase, Web of Science, the Cochrane Library, CNKI, and Wanfang Data until May 17, 2018. The pooled OR and 95% CI were used to estimate the relationship between EBV infection and BC risk using a fixed or random-effects model depending on heterogeneity. Subgroup analysis and meta-regression were used to explore the heterogeneity. Publication bias was assessed using Egger's and Harbord's tests.

RESULTS

A total of 16 studies with 1,279 patients and 814 controls were reviewed based on our inclusion and exclusion criteria. Compared with the control group, EBV infection had a significant association with BC risk (OR 4.75, 95% CI 2.53-8.92, p < 0.01) with significant heterogeneity observed (I2 = 65.3%). The subgroup analysis revealed that region and tissue type might explain potential sources of heterogeneity. The sensitivity analyses yielded stable results. No significant publication bias was observed.

CONCLUSION

The current results suggest that EBV infection is significantly associated with increased risk of BC.

Epstein-Barr virus and risk of breast cancer: a systematic review and meta-analysis

Despite the numerous publications regarding the role of Epstein-Barr virus (EBV) in breast cancer development, the topic has still remained controversial. The aim of the meta-analysis was to estimate the overall prevalence of EBV in the breast cancer population, and to investigate the association between EBV and breast cancer risk. The overall prevalence of EBV was calculated 26.37% (95% CI: 22-31%) from the 44 included studies. Meta-analysis of 30 case-control studies showed that the pooled association between EBV and risk of breast cancer is odds ratio 4.74 (95% CI: 2.92-7.69; Z = 6.30; p < 0.0001). Our analyses indicate a strong statistical relationship between EBV infection and risk of breast cancer, suggesting a potential role of EBV infection in the development of breast cancer.

Breast cancer and cytomegalovirus

PURPOSE

To determine whether cytomegalovirus is causally associated with breast cancer and whether cytomegalovirus should be categorised as an oncogenic virus.

METHODS

We undertook a review of published epidemiological and laboratory studies, using established causal criteria: Bradford Hill criteria to determine whether cytomegalovirus is associated with breast cancer; and Evans/Mueller criteria to determine whether cytomegalovirus should be categorised as an oncogenic virus.

RESULTS

Although there are inconsistencies in the findings of published epidemiological and laboratory studies, these may be explained by factors such as: differences in timing of blood samples, differences in selection of cases and controls, or high cytomegalovirus seroprevalence among participants in the epidemiological studies; and, in the laboratory studies, differences in sample preparations, age of sample, whether or not paired breast cancer and normal breast tissue samples were used, differences in the tests, primers and/or antibodies used, differences in histological types of breast cancer studied, and/or features of the virus.

CONCLUSIONS

Overall, the results of published studies of cytomegalovirus and breast cancer suggest cytomegalovirus is a causal factor for at least some types of breast cancer. If the evidence for a link between cytomegalovirus and breast cancer continues to strengthen, further research could lead to: targeted screening; therapy using antiviral drugs; and, perhaps, primary prevention of a significant proportion of breast cancer. Vaccination against viruses has already been shown to be effective in preventing cervix and liver cancer; cytomegalovirus vaccines are already under development.

Viral infections and breast cancer - A current perspective

Sporadic human breast cancer is the most common cancer to afflict women. Since the discovery, decades ago, of the oncogenic mouse mammary tumour virus, there has been significant interest in the potential aetiologic role of infectious agents in sporadic human breast cancer. To address this, many studies have examined the presence of viruses (e.g. papillomaviruses, herpes viruses and retroviruses), endogenous retroviruses and more recently, microbes, as a means of implicating them in the aetiology of human breast cancer. Such studies have generated conflicting experimental and clinical reports of the role of infection in breast cancer. This review evaluates the current evidence for a productive oncogenic viral infection in human breast cancer, with a focus on the integration of sensitive and specific next generation sequencing technologies with pathogen discovery. Collectively, the majority of the recent literature using the more powerful next generation sequencing technologies fail to support an oncogenic viral infection being involved in disease causality in breast cancer. In balance, the weight of the current experimental evidence supports the conclusion that viral infection is unlikely to play a significant role in the aetiology of breast cancer.

Epstein-Barr virus is present in the brain of most cases of multiple sclerosis and may engage more than just B cells

Multiple sclerosis (MS) is a chronic neuroinflammatory condition of the central nervous system (CNS). It is a major cause of neurological disability in young adults, particularly women. What triggers the destruction of myelin sheaths covering nerve fibres is unknown. Both genetic and infectious agents have been implicated. Of the infectious agents, Epstein-Barr virus (EBV), a common herpesvirus, has the strongest epidemiological and serological evidence. However, the presence of EBV in the CNS and demonstration of the underlying mechanism(s) linking EBV to the pathogenesis of MS remain to be elucidated. We aimed at understanding the contribution of EBV infection in the pathology of MS. We examined 1055 specimens (440 DNA samples and 615 brain tissues) from 101 MS and 21 non-MS cases for the presence of EBV using PCR and EBER-in situ hybridization (EBER-ISH). EBV was detected by PCR and/or EBER-ISH in 91/101 (90%) of MS cases compared to only 5/21 (24%) of non-MS cases with other neuropathologies. None of the samples were PCR positive for other common herpesviruses (HSV-1, CMV, HHV-6). By quantitative PCR, EBV viral load in MS brain was mainly low to moderate in most cases. However, in 18/101 (18%) of MS cases, widespread but scattered presence of EBV infected cells was noted in the affected tissues by EBER-ISH. Immunohistochemical analysis of EBV gene expression in the 18 heavily infected cases, revealed that the EBV latent protein EBNA1, and to a lesser extent the early lytic protein BZLF1 were expressed. Furthermore, using double-staining we show for the first time that astrocytes and microglia, in addition to B-cells can also be infected. To the best of our knowledge, this is the most comprehensive study demonstrating that EBV is present and transcriptionally active in the brain of most cases of MS and supports a role for the virus in MS pathogenesis. Further studies are required to address the mechanism of EBV involvement in MS pathology.

Association of Epstein - Barr virus and breast cancer in Eritrea

BACKGROUND

The oncogenic potential of Epstein-Barr virus (EBV) in breast cancer is being increasingly recognized. Despite some controversies regarding such role, new evidence is suggesting a culpability of EBV in breast cancer, particularly in Africa where the virus has been originally associated with causation of several solid and hematological malignancies. One example is a report from Sudan implicating EBV as a prime etiologic agent for an aggressive type of breast cancer, where nearly 100% of tumor tissues were shown to carry viral signatures. To get a broader view on such association, other nearby countries should be investigated. The present study aims to determine the prevalence and possible associations of the virus in Eritrean breast cancer patients.

METHODS

Detection of EBV genome using primers that target Epstein Barr Encoded RNA (EBER) gene and Latent Membrane Protein-1 (LMP-1) gene sequences was performed by polymerase chain reaction (PCR) on DNA samples extracted from 144 formalin fixed paraffin embedded breast cancer tissues and 63 non-cancerous breast tissue as control group. A subset of PCR positive samples was evaluated for EBER gene expression by in situ hybridization (ISH). Expression of Latent Membrane Protein-2a (LMP2a) was also assessed by immunohistochemistry in a subset of 45 samples.

RESULTS

Based on PCR results, EBV genome signals were detected in a total of 40 samples (27.77%) as compared to controls (p-value = 0. 0031) with a higher sensitivity when using the EBER primers. Five out of the 14 samples stained by EBER-ISH 35.71% were positive for the virus indicating the presence of the viral genome within the tumor cells. Of those stained for IHC 7 (15.55%) were positive for LMP2a showing low viral protein frequency.

CONCLUSIONS

Based on these findings it can be concluded that EBV in Eritrea is associated with a smaller subset of tumors, unlike neighboring Sudan, thus pointing to possible differences in population predisposition and diseases epidemiology.

Evidence for the association of Epstein-Barr Virus in breast cancer in Indian patients using in-situ hybridization technique

Epstein-Barr Virus (EBV) is etiologically linked to Burkitt lymphoma (BL), nasopharyngeal carcinoma, post-transplant lymphomas, Hodgkin disease, and possibly other tumors. However, the association of oncogenic EBV with breast carcinoma (BC) is still controversial and a matter of debate. We aimed to study the presence of EBV genome in BC cases in Indian patients and its association with the clinicopathological features. The formalin fixed paraffin embedded tissues from 83 women with primary invasive BC were studied for the presence of EBV by in-situ hybridization (ISH) technique for Epstein-Barr Virus Encoded RNA (EBER) with appropriate controls. Correlation of EBER-ISH positivity with clinicopathological features was performed using Fisher exact test and P<.05 was considered as significant. Eighty-three BC cases were comprised of 47 (56.5%) triple negative breast cancers (TNBC), 17 (20.5%) hormone positive and 19 (22.9%) HER2 positive cases. Of 83 cases, 25 cases (30.1%) were positive for EBER-ISH test. The positivity was restricted to the tumor cells and not seen in the surrounding breast lobules. EBER-ISH positivity was statistically associated with larger tumor size (52.6% in >5 cm tumors vs 19.3% in ≤5 cm; P=.014) and with TNBCs (21/47 [44.7%] in TNBCs vs 4/36 [11.1%] in non-TNBCs; P=.001). A possible causal association of EBV in BC cases in Indian patients is suggested by high frequency of EBER-ISH positivity noted in our study. This might have therapeutic significance because of the possible role of EBV specific cytotoxic T cells in targeting EBV associated tumor cells and can be considered as a potential targeted therapy. To the best of our knowledge, this is the first study from India to address this issue using EBER-ISH technique.

Variation in risk and outcomes of Epstein-Barr virus-associated breast cancer by epidemiologic characteristics and virus detection strategies: an exploratory study

PURPOSE

A relationship of Epstein-Barr virus (EBV) and breast cancer etiology and outcome may have clinical utility and potential to enhance understanding of tumor biology. Research to date has yielded variable results, likely reflecting differing virus detection assays and unaddressed epidemiologic heterogeneity across studies.

METHODS

Applying our novel, five-target assay detection strategy in an exploratory study, we examined demographic, clinical, and tumor characteristics, and overall survival, associated with EBV positivity in breast adenocarcinomas from 59 non-Hispanic white and 68 Hispanic women sampled by age (<50, 50+) and stage (localized, regional/remote) and examined associations based on single assay targets.

RESULTS

EBV was localized only to lymphocytes. Nevertheless, viral prevalence, although low, varied across patient subgroups. Adjusted odds ratios (OR) for EBV positivity were lower for younger Hispanic than white women (p _interaction = 0.05), and marginally higher for larger [OR (95% confidence intervals) 1.03 (1.00-1.05) per mm increase] and right-sided [2.8 (0.97-7.8)] tumors. In whites, ORs were marginally higher for larger tumors [1.04 (1.00-1.07)] and marginally lower for age 50+ [0.24 (0.06-1.03)]; in Hispanics, ORs were higher for ER negative [5.6 (1.1-30.5)], and marginally higher for right-sided, tumors [5.8 (0.94-36.2)]. Survival was suggestively poorer for EBV-positive than EBV-negative tumors in older women with localized disease. EBV associations differed across single assay targets, indicating variation in prior findings likely due to assay performance.

CONCLUSIONS

The differing EBV associations by age and race/ethnicity suggest a non-random role of EBV in breast cancer and support further study using multi-target assays, relevant epidemiologic design, and a larger study sample.

A simple procedure for the extraction of DNA from long-term formalin-preserved brain tissues for the detection of EBV by PCR

Long-term formalin fixed brain tissues are potentially an important source of material for molecular studies. Ironically, very few protocols have been published describing DNA extraction from such material for use in PCR analysis. In our attempt to investigate the role of Epstein-Barr virus (EBV) in the pathogenesis of multiple sclerosis (MS), extracting PCR quality DNA from brain samples fixed in formalin for 2-22 years, proved to be very difficult and challenging. As expected, DNA extracted from these samples was not only of poor quality and quantity, but more importantly, it was frequently found to be non-amplifiable due to the presence of PCR inhibitors. Here, we describe a simple and reproducible procedure for extracting DNA using a modified proteinase K and phenol-chloroform methodology. Central to this protocol is the thorough pre-digestion washing of the tissues in PBS, extensive digestion with proteinase K in low SDS containing buffer, and using low NaCl concentration during DNA precipitation. The optimized protocol was used in extracting DNA from meninges of 26 MS and 6 non-MS cases. Although the quality of DNA from these samples was generally poor, small size amplicons (100-200 nucleotides) of the house-keeping gene, β-globin could be reliably amplified from all the cases. PCR for EBV revealed positivity in 35% (9/26) MS cases, but 0/6 non-MS cases. These findings indicate that the method described here is suitable for PCR detection of viral sequences in long-term formalin persevered brain tissues. Our findings also support a possible role for EBV in the pathogenesis of MS.

Cytomegalovirus and Epstein-Barr virus in breast cancer

Findings of polymerase chain reaction (PCR) studies of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) and breast cancer vary, making it difficult to determine whether either, both, or neither virus is causally associated with breast cancer. We investigated CMV and EBV in paired samples of breast cancer and normal breast tissue from 70 women using quantitative PCR. A serum sample from each woman was tested for CMV and EBV IgG. To place our results in context, we reviewed the existing literature and performed a meta-analysis of our results together with previous PCR studies of EBV, CMV, and breast cancer. Of the serology samples, 67 of 70 (96%) were EBV IgG positive and 49 of 70 (70%) were CMV IgG positive. QPCR detected EBV in 24 (34%) of the tumour and 9 (13%) of the paired normal specimens and CMV in 0 (0%) of the tumour and 2 (3%) of the paired normal specimens. Our findings, together with earlier results summarised in the meta-analysis, suggest several possibilities: variable findings may be due to limitations of molecular analyses; 'hit and run' oncogenesis may lead to inconsistent results; one or both viruses has a role at a later stage in breast cancer development; infection with multiple viruses increases breast cancer risk; or neither virus has a role. Future studies should focus on ways to investigate these possibilities, and should include comparisons of breast cancer tissue samples with appropriate normal tissue samples.

Global burden of deaths from Epstein-Barr virus attributable malignancies 1990-2010

Background

Epstein-Barr virus (EBV) is an oncogenic virus implicated in the pathogenesis of a number of human malignancies of both lymphoid and epithelial origin. Thus, a comprehensive and up-to-date analysis focused on the global burden of EBV-attributable malignancies is of significant interest.

Methods

Based on published studies, we estimated the proportion of Burkitt’s lymphoma (BL), Hodgkin’s lymphoma (HL), nasopharyngeal carcinoma NPC), gastric carcinoma (GC) and post-transplant lymphoproliferative disease (PTLD) attributable to EBV, taking into consideration age, sex and geographical variations. This proportion was then imputed into the Global Burden of Disease 2010 dataset to determine the global burden of each EBV-attributable malignancy in males and females in 20 different age groups and 21 world regions from 1990 to 2010.

Results

The analysis showed that the combined global burden of deaths in 2010 from all EBV-attributable malignancies was 142,979, representing 1.8% of all cancer deaths. This burden has increased by 14.6% over a period of 20 years. All 5 EBV-attributable malignancies were more common in males in all geographical regions (ratio of 2.6:1). Gastric cancer and NPC accounted for 92% of all EBV-attributable cancer deaths. Almost 50% of EBV-attributed malignancies occurred in East Asia. This region also had the highest age-standardized death rates for both NPC and GC.

Conclusions

Approximately 143,000 deaths in 2010 were attributed to EBV-associated malignancies. This figure is likely to be an underestimate since some of the less prevalent EBV-associated malignancies have not been included. Moreover, the global increase in population and life-expectancy will further increase the overall burden of EBV-associated cancer deaths. Development of a suitable vaccine could have a substantial impact on reducing this burden.

Electronic supplementary material

The online version of this article (doi:10.1186/1750-9378-9-38) contains supplementary material, which is available to authorized users.

Role of viruses in the development of breast cancer

The most common cancer worldwide among women is breast cancer. The initiation, promotion, and progression of this cancer result from both internal and external factors. The International Agency for Research on Cancer stated that 18-20% of cancers are linked to infection, and the list of definite, probable, and possible carcinogenic agents is growing each year. Among them, biological carcinogens play a significant role. In this review, data covering infection-associated breast and lung cancers are discussed and presented as possible involvements as pathogens in cancer. Because carcinogenesis is a multistep process with several contributing factors, we evaluated to what extent infection is significant, and concluded that members of the herpesvirus, polyomavirus, papillomavirus, and retrovirus families definitely associate with breast cancer. Detailed studies of viral mechanisms support this conclusion, but have presented problems with experimental settings. It is apparent that more effort needs to be devoted to assessing the role of these viruses in carcinogenesis, by characterizing additional confounding and synergistic effects of carcinogenic factors. We propose that preventing and treating infections may possibly stop or even eliminate certain types of cancers.

Exploring the prevalence of ten polyomaviruses and two herpes viruses in breast cancer

Several different viruses have been proposed to play a role in breast carcinogenesis. The aim of this study was to investigate the prevalence of a subset of viruses in breast cancer tissue. We investigated the prevalence of 12 DNA viruses: EBV and CMV from the Herpesviridae family and SV40, BKV, JCV, MCV, WUV, KIV, LPV, HPyV6, HPyV7, and TSV from the Polyomaviridae family in 54 fresh frozen breast tumour specimens. Relevant clinical data and basic lifestyle data were available for all patients. The tissue samples were DNA extracted and real-time PCR assays were used for viral detection.The highest prevalence, 10% (5/54), was found for EBV. MCV, HPyV6, and HPyV7 were detected in single patient samples (2% each), while WUV, KIV, JCV, BKV, LPV, SV40, TSV and CMV were not detected in the 54 breast cancer specimens analysed here. Further investigations are needed to elucidate the potential role of viruses, and particularly EBV, in breast carcinogenesis.

Exacerbated metastatic disease in a mouse mammary tumor model following latent gammaherpesvirus infection

Background

Controversy exists as to the ability of human gammaherpesviruses to cause or exacerbate breast cancer disease in patients. The difficulty in conducting definitive human studies can be overcome by investigating developing breast cancer in a mouse model. In this study, we utilized mice latently infected with murine gammaherpesvirus 68 (HV-68) to question whether such a viral burden could exacerbate metastatic breast cancer disease using a mouse mammary tumor model.

Results

Mice latently infected with HV-68 had a similar primary tumor burden, but much greater metastatic disease, when compared to mock treated mice given the transplantable tumor, 4 T1. This was true for lung lesions, as well as secondary tumor masses. Increased expression of pan-cytokeratin and VEGF-A in tumors from HV-68 infected mice was consistent with increased metastatic disease in these animals. Surprisingly, no viral particles could be cultured from tumor tissues, and the presence of viral DNA or RNA transcripts could not be detected in primary or secondary tumor tissues.

Conclusions

Latent HV-68 infection had no significant effect on the size of primary 4 T1 mammary tumors, but exacerbated the number of metastatic lung lesions and secondary tumors when compared to mock treated mice. Increased expression of the tumor marker, pan-cytokeratin, and VEGF-A in tumors of mice harboring latent virus was consistent with an exacerbated metastatic disease. Mechanisms responsible for this exacerbation are indirect, since no virus could be detected in cancerous tissues.

No evidence for the involvement of XMRV or MCV in the pathogenesis of breast cancer

Background:

The aetiology of breast cancer remains elusive. A viral aetiology has been proposed, but to date no virus has been conclusively demonstrated to be involved. Recently, two new viruses, namely Merkel cell polyomavirus (MCV) and xenotropic murine leukaemia virus-related virus (XMRV) have been identified and implicated in the pathogenesis of Merkel cell carcinoma (MCC) and familial form of prostate cancer, respectively.

Methods:

We examined 204 samples from 58 different cases of breast cancer for presence of MCV or XMRV by PCR. Samples consisted of both malignant and non-malignant tissues. Additionally, we included 6 cases of MCC and 12 cases of prostate cancer as potential controls for MCV and XMRV, respectively.

Results:

All of the breast cancer samples examined were negative for both MCV and XMRV. However, 4/6 MCC and 2/12 prostate cancer samples were found to be positive for MCV and XMRV, respectively. Sequence analysis of the amplified products confirmed that these sequences belonged to MCV and XMRV.

Conclusion:

We conclude that there is no evidence for the involvement of MCV or XMRV in the pathogenesis of breast cancer. What role these viruses have in the pathogenesis of MCC and prostate carcinomas remains to be demonstrated.

Immune modulation during latent herpesvirus infection

Nearly all human beings, by the time they reach adolescence, are infected with multiple herpesviruses. At any given time, this family of viruses accounts for 35-40 billion human infections worldwide, making herpesviruses among the most prevalent pathogens known to exist. Compared to most other viruses, herpesviruses are also unique in that infection lasts the life of the host. Remarkably, despite their prevalence and persistence, little is known about how these viruses interact with their hosts, especially during the clinically asymptomatic phase of infection referred to as latency. This review explores data in human and animal systems that reveal the ability of latent herpesviruses to modulate the immune response to self and environmental antigens. From the perspective of the host, there are both potentially detrimental and surprisingly beneficial effects of this lifelong interaction. The realization that latent herpesvirus infection modulates immune responses in asymptomatic hosts forces us to reconsider what constitutes a 'normal' immune system in a healthy individual.