High levels of Epstein-Barr virus DNA in latently infected gastric adenocarcinoma

Multi-Omic Data Integration Suggests Putative Microbial Drivers of Aetiopathogenesis in Mycosis Fungoides

BACKGROUND

Mycosis fungoides (MF) represents the most prevalent entity of cutaneous T cell lymphoma (CTCL). The MF aetiopathogenesis is incompletely understood, due to significant transcriptomic heterogeneity and conflicting views on whether oncologic transformation originates in early thymocytes or mature effector memory T cells. Recently, using clinical specimens, our group showed that the skin microbiome aggravates disease course, mainly driven by an outgrowing, pathogenic S. aureus strain carrying the virulence factor spa, which was shown by others to activate the T cell signalling pathway NF-κB.

METHODS

To explore the role of the skin microbiome in MF aetiopathogenesis, we here performed RNA sequencing, multi-omic data integration of the skin microbiome and skin transcriptome using Multi-Omic Factor Analysis (MOFA), virome profiling, and T cell receptor (TCR) sequencing in 10 MF patients from our previous study group.

RESULTS

We observed that inter-patient transcriptional heterogeneity may be largely attributed to differential activation of T cell signalling pathways. Notably, the MOFA model resolved the heterogenous activation pattern of T cell signalling after denoising the transcriptome from microbial influence. The MOFA model suggested that the outgrowing S. aureus strain evoked signalling by non-canonical NF-κB and IL-1B, which in turn may have fuelled the aggravated disease course. Further, the MOFA model indicated aberrant pathways of early thymopoiesis alongside enrichment of antiviral innate immunity. In line with this, viral prevalence, particularly of Epstein-Barr virus (EBV), trended higher in both lesional skin and the blood compared to nonlesional skin. Additionally, TCRs in both MF skin lesions and the blood were significantly more likely to recognize EBV peptides involved in latent infection.

CONCLUSIONS

First, our findings suggest that S. aureus with its virulence factor spa fuels MF progression through non-canonical NF-κB and IL-1B signalling. Second, our data provide insights into the potential role of viruses in MF aetiology. Last, we propose a model of microbiome-driven MF aetiopathogenesis: Thymocytes undergo initial oncologic transformation, potentially caused by viruses. After maturation and skin infiltration, an outgrowing, pathogenic S. aureus strain evokes activation and maturation into effector memory T cells, resulting in aggressive disease. Further studies are warranted to verify and extend our data, which are based on computational analyses.

The Distal Promoter of the B438L Gene of African Swine Fever Virus Is Responsible for the Transcription of the Alternatively Spliced B169L

The B169L protein (pB169L) of African swine fever virus (ASFV) is a structural protein with an unidentified function during the virus replication. The sequences of the B169L gene and the downstream B438L gene are separated by short intergenic regions. However, the regulatory mode of the gene transcription remains unknown. Here, we identified two distinct promoter regions and two transcription start sites (TSSs) located upstream of the open reading frame (ORF) of B438L. Using the promoter reporter system, we demonstrated that the cis activity of the ORF proximal promoter exhibited significantly higher levels compared with that of the distal promoter located in the B169L gene. Furthermore, transfection with the plasmids with two different promoters for B438L could initiate the transcription and expression of the B438L gene in HEK293T cells, and the cis activity of the ORF proximal promoter also displayed higher activities compared with the distal promoter. Interestingly, the B438L distal promoter also initiated the transcription of the alternatively spliced B169L mRNA (B169L mRNA2) encoding a truncated pB169L (tpB169L) (amino acids 92-169), and the gene transcription efficiency was increased upon mutation of the initiation codon located upstream of the alternatively spliced B169L gene. Taken together, we demonstrated that the distal promoter of B438L gene initiates the transcription of both the B438L mRNA and B169L mRNA2. Comprehensive analysis of the transcriptional regulatory mode of the B438L gene is beneficial for the understanding of the association of B438L protein and pB169L and the construction of the gene-deleted ASFV.

Investigating the relationship between Epstein-Barr virus infection and gastric cancer: A systematic review and meta-analysis

Background and Aims

Gastric cancer (GC) is a common cancer type worldwide, and various factors can be involved in its occurrence. One of these factors is Epstein-Barr virus (EBV) infection. In this regard, a systematic review and meta-analysis was conducted to achieve a better understanding of the EBV prevalence in GC samples.

Methods

English databases were searched and studies that reported the prevalence and etiological factors of EBV related to GC from July 2007 to November 2022 were retrieved. The reported data were selected based on the inclusion and exclusion criteria. The pooled prevalence of EBV infection with 95% confidence intervals was calculated. Quality assessment, heterogeneity testing, and publication bias assessment were also performed. The literature search showed 953 studies, of which 87 studies met our inclusion criteria and were used for meta-analysis.

Results

The pooled prevalence of EBV infection related to GC was estimated to be 9.5% (95% confidence interval [CI]: 8.2%-11%) in the general population. The prevalence of EBV infection related to GC by gender was 13.5% (95% CI: 11.1%-16.3%) in males and 7.6% (95% CI: 5.4%-10.6%) in females. No significant differences were observed in terms of geographical region. Out of the 87 studies included in the meta-analysis, the most common diagnostic test was in situ hybridization (58 cases).

Conclusions

Altogether, the results indicated that EBV infection is one of the important factors in the development of GC. However, this does not necessarily mean that EBV infection directly causes GC since other factors may also be involved in the development of GC. Therefore, it is recommended to conduct extensive epidemiological studies on various aspects of the relationship between this virus and GC, which can provide valuable information for understanding the relationship between EBV and GC.

Epstein-Barr virus genotype-1 and Mediterranean + strain in gastric cancer biopsies of Ghanaian patients

Gastric cancer (GC) prevalence is on the increase in Ghana, and Epstein-Barr virus (EBV) is one of the factors that have been implicated in the etiology of the cancer. It is therefore important to know the contribution of EBV genotype and strains that are associated with GC. In this study, we aimed at genotyping EBV and determining predominant strains in GC biopsies in Ghanaian patients. Genomic DNA was extracted from 55 GC biopsies (cases) and 63 normal gastric tissues (controls) were amplified by polymerase chain reaction (PCR) using specific primers for EBV detection and genotyping followed by PCR fragments sequencing. Epstein-Barr virus positivity were 67.3% and 49.2% in the GC and normal biopsies, respectively. Both cases and controls had the Mediterranean + strain of EBV. The predominant genotype of the virus in the GC cases was genotype-1 (75.7%) compared to 66.7% of genotype-2 among the control group. Infection was associated with GC in the study population (OR = 2.11, P = 0.014, 95% CI: 1.19 - 3.75), and EBV genotype-1 significantly increased the risk of GC (OR = 5.88, P < 0.0001, 95% CI: 3.18-10.88). The mean EBV load in the cases (3.507 ± 0.574) was significantly higher than in the controls (2.256 ± 0.756) (P < 0.0001). We conclude that EBV, especially Mediterranean + genotype-1, was the predominant strain in GC biopsies and GC type or progression is independent of the viral load.

Estimating the Global Burden of Epstein-Barr Virus-Associated Gastric Cancer: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Evidence suggests that a fraction of new gastric cancer cases may be etiologically associated with Epstein-Barr virus (EBV), a known carcinogenic agent. We aimed to systematically explore the proportion of EBV-positive gastric cancer.

METHODS

We did a systematic review (PROSPERO CRD42020164473) from January 1990 to August 2021. For each country and geographical region with available data, pooled prevalence and corresponding 95% confidence intervals (CIs) of EBV in gastric tumors were calculated for 3 subtypes of gastric adenocarcinoma (conventional adenocarcinoma, lymphoepithelioma-like gastric carcinoma, and remnant/stump carcinoma). For conventional adenocarcinoma, prevalence ratios (PRs) were presented for sex, Lauren's classification, gastric cancer stage, and anatomical location of the stomach.

RESULTS

In 220 eligible studies including over 68,000 cases of conventional gastric adenocarcinoma, EBV prevalence in tumor cells was 7.5% (95% CI, 6.9%-8.1%) and was higher in men compared with women (PR, 2.1; 95% CI, 1.9-2.4), in diffuse type compared with intestinal type (PR, 1.3; 95% CI, 1.1-1.5), and in the proximal region compared with the distal region (PR, 2.5; 95% CI, 2.0-3.1). There was no difference in EBV prevalence by gastric cancer stage. EBV prevalence was 75.9% (95% CI, 62.8%-85.5%) among lymphoepithelioma-like gastric carcinoma and 26.3% (95% CI, 22.2%-32.0%) among remnant or stump carcinoma.

CONCLUSIONS

Assuming a causal association between EBV and gastric cancer, our findings, when applied to the GLOBOCAN 2020 gastric cancer incidence, suggest that primary prevention such as the development of an effective EBV vaccine might prevent 81,000 EBV-associated gastric cancer cases worldwide annually.

Quantitative analysis of Epstein-Barr virus DNA in plasma and stomach biopsies of patients with gastric cancer

Epstein-Barr virus (EBV) associated gastric carcinoma (EBVaGC) is a subtype of gastric cancer with distinct histological and molecular features. The study aimed to assess the EBV DNA copy number and the prevalence of EBVaGC in gastric cancer samples taken from Iranian patients. The next aim was to assess whether the DNA and microRNAs EBV are present in plasma. EBV load was analyzed in 68 gastric cancer biopsies and compared with the results of EBV-encoded small RNA in situ hybridization (EBER-ISH) test in these patients. After the detection of 6 EBV miRNAs in gastric tissue by stem-loop RT-PCR, plasma samples were evaluated for the viral load and EBV miRNAs. Four gastric cancer cases were EBER -ISH positive (5.8%), with a significantly higher viral load than the remaining cases, 47,781 vs. 1909 copies/μg of tissue DNA. Here, was also found a significant difference in plasma EBV load between EBER-positive and EBER-negative cases. Although EBV miRNAs were detectable in all the EBER-positive tumors, the test did not detect any of these miRNAs among the plasma samples tested. Our data indicate that the prevalence of EBVaGC among Iranian patients with gastric cancer is lower than the global prevalence and although none of the EBV miRNAs were detected in plasma, evaluation of EBV microRNAs in tumor tissue, especially miR-BART7-3p, may constitute useful biomarkers for diagnosis of EBVaGC.

Molecular pathogenesis, targeted therapies, and future perspectives for gastric cancer

Gastric cancer is a major source of global cancer mortality with limited treatment options and poor patient survival. As our molecular understanding of gastric cancer improves, we are now beginning to recognize that these cancers are a heterogeneous group of diseases with incredibly unique pathogeneses and active oncogenic pathways. It is this molecular diversity and oftentimes lack of common oncogenic driver mutations that bestow the poor treatment responses that oncologists often face when treating gastric cancer. In this review, we will examine the treatments for gastric cancer including up-to-date molecularly targeted therapies and immunotherapies. We will then review the molecular subtypes of gastric cancer to highlight the diversity seen in this disease. We will then shift our discussion to basic science and gastric cancer mouse models as tools to study gastric cancer molecular heterogeneity. Furthermore, we will elaborate on a molecular process termed paligenosis and the cyclical hit model as key events during gastric cancer initiation that impart nondividing mature differentiated cells the ability to re-enter the cell cycle and accumulate disparate genomic mutations during years of chronic inflammation and injury. As our basic science understanding of gastric cancer advances, so too must our translational and clinical efforts. We will end with a discussion regarding single-cell molecular analyses and cancer organoid technologies as future translational avenues to advance our understanding of gastric cancer heterogeneity and to design precision-based gastric cancer treatments. Elucidation of interpatient and intratumor heterogeneity is the only way to advance future cancer prevention, diagnoses and treatment.

Circulating Epstein-Barr virus DNA associated with hepatic impairment and its diagnostic and prognostic role in patients with gastric cancer

Epstein–Barr virus (EBV) infection may affect all tissues and organs of the body. Little is known about the impact of this entity on its systematic incorporation in patients with gastric cancer (GC). This study enrolled a total of 113 GC patients with EBV infection (EBVaGC) and 167 GC patients without EBV infection (EBVnGC). It was found that the CRP levels (indicative of inflammatory status) were significantly increased in EBVaGC compared with those in EBVnGC (12.11 mg/L vs. 5.72 mg/L, P = 0.008), but WBC and neutrophils counts were similar in both groups (P > 0.05). Consistent elevations in the levels of liver enzymes, ALP and GGT, with incompatible alterations in ALT or AST were observed in EBVaGC. Slightly prolonged coagulation indices, PT and INR, and decreased albumin consistently suggested impaired synthesis capability of the liver in EBVaGC (all P < 0.05). The level of circulating EBV DNA was positively correlated with the level of GGT, tumor marker CA72-4 and the lymphocyte infiltration in tumor tissues (all P < 0.05). Of note, the EBV associated high-lymphocyte infiltrated tissues presented rich CD8 + T cells. Circulating EBV DNA further showed a predictive role in distinguishing EBVaGC from EBVnGC (AUC 0.79, 95% CI 0.73 to 0.85, P < 0.001), and was associated closely with better overall survival (HR 0.45, 95% CI 0.21 to 0.96, P = 0.039). EBV infection in patients with gastric cancer may be linked to hepatic impairment and immune response. Circulating cell-free EBV DNA is not only a biomarker for the screening of an EBV-related GC subtype but is also an independently prognosis factor for the long-term survival benefit in GC patients.

Rate of Epstein-Barr Virus in Gastric Adenocarcinoma in Egyptian Patients in View of the WHO Classification and Correlation with p16 Immunoreactivity

BACKGROUND AND AIM: Gastric cancer (GC) is one of the top causes of cancer-related deaths worldwide. According to the Cancer Genome Atlas, there are four subtypes of GC, with the Epstein-Barr virus (EBV) subtype accounting for about 10% of cases. EBV infection causes EBV-associated GC (EBVaGC). The previous research suggested that the presence of the EBV viral genome in gastric carcinomas could be used as a surrogate marker for targeted therapy and optimal GC treatment. AIM: We aimed to explore the rate of EBV involvement in gastric carcinogenesis from molecular perspective view and to evaluate the role of the tumor-suppressor protein p16 as a marker for diagnosis in GC Egyptian patients in relation to EBV infection. METHODS: One hundred-four surgically resected GC cases were analyzed. Two methods including quantitative real-time polymerase chain reaction (qPCR) for detecting EBV-derived latent membrane protein-1 (LMP-1) and Epstein-Barr nuclear antigen-1 (EBNA-1) genes as well as immunohistochemistry (IHC) detection of LMP-1 protein and p16 protein on paraffinized tissue blocks were applied. RESULTS: Using IHC, p16 protein was presented in 90/104 (86.5%) of the GC cases, and EBV LMP-1 was detected in 4 cases (3.84%). qPCR detected 14 cases positive for EBV (13.46%). In EBV positive cases detected using qPCR, no expression of p16 was detected. CONCLUSION: EBVaGC has a low incidence in Egypt; loss of p16 expression was recognized in EBVaGC and could be considered as a promising biomarker of EBVaGC. The combination of the two methods IHC and qPCR in addition to p16 is recommended for improving the accuracy of identification of infected cancer.

Higher viral load of Epstein-Barr virus in gastric cancer compared with non-cancerous gastroduodenal tissues

INTRODUCTION

Epstein-Barr Virus (EBV)-associated gastric cancer is a distinct molecular subtype of gastrointestinal carcinomas as defined by the Cancer Genome Atlas.

METHODS

In the present study 237 samples from Iranian patients diagnosed with gastric cancer and gastroduodenal disease were retrospectively examined for EBV infection by quantitative Real-Time PCR.

RESULTS

Of the 237 samples tested, EBV DNA was detected in 37 samples (15.6%), in 13 of the 81 gastric cancer cases (16%), and 24 of the 156 non-cancerous samples (15.4%). The EBV infection rate was found higher in patients with gastric ulcer (35%) and duodenal ulcer (21.9%) compared to patients with gastric cancer (16%) and gastritis (19.6%). The EBV-encoded small RNA (EBER) copy number in the gastric cancer group (mean = 2.14×10^-1 with range of 2.14×10^-2 to 4.10×10^-1 copies/ cell) was higher than gastroduodenal diseases group (mean = 1.39×10^-2 with range 1.11×10^-3 to 2.35×10^-2 copies/ cell), and this difference was statistically significant (P >0.001).

CONCLUSION

The higher number of copies of EBV-EBER in the gastric cancer group compared to the non-cancer group confirmed the possible role of EBV in inducing cancer.

Co-infection relationship with Epstein-Barr virus in gastroduodenal diseases with Helicobacter Pylori. Quantitative PCR and EBNA-1 gene-based approach

Objective: Helicobacter pylori (Hp) and Epstein-Barr virus (EBV) are involved in gastric cancer (GC) etiology. EBV/Hp co- infection was thought synergistically increase gastroduodenal disease occurence. We aimed to determine the presence of EBV/Hp co-infection in gastroduodenal diseases. Methods: The study group had 68 Hp (+) cases [25 GC, 13 IM (intestinal metaplasia), 30 PU (peptic ulcer)], and the control group had 40 NUD (non-ulcer dyspepsia) cases [20 Hp+, 20 Hp-]. EBV-DNA was detected by non-polymorphic EBNA-1 gene-based qPCR. EBV/EBNA-1 IgG levels were determined by quantitative and qualitative ELISA methods, respectively. Results: EBV-DNA positivity was 32% (8/25), 6.6% (2/30) and 5% (1/20) in GC, PU and NUD Hp (+) cases, respectively. There was a significant difference (p = 0.001) between GC (32%) and NUD Hp (+) (5%) cases in terms of EBV-DNA positivity. Mean EBV-DNA copy numbers were 6568.54 ± 20351, 30.60 ± 159.88 and 13.85 ± 61.93 for GC, PU, and NUD, respectively. In terms of the mean EBV-DNA copy number, a significant difference was found between the groups (p = 0.005). In terms of EBV/EBNA-1 IgG antibody positivity, no significant difference was found between GC and NUD cases (p = 0.248). EBV DNA positivity was found to be significant (odds ration [OR] = 26.71 (p=0.009, %95CI 2.286- 312.041) in multivariate logistic regression. Conclusioin: Although we had a small number of GC cases, it can be suggested that the estimated risk created by the synergistic effect based on the addition of EBV increased 26 times in the presence of Hp in GC.

Detection of Epstein-Barr virus in gastric adenocarcinoma: qPCR and FISH comparison

EBV-associated gastric cancer accounts for about 10% of all gastric carcinomas worldwide. We aimed to verify the prevalence of EBV in gastric adenocarcinoma samples using FISH and qPCR and comparing the results obtained by both techniques. Gastric cancer samples from 191 cases were analyzed. The FISH assay was performed to detect small EBV RNAs (EBER1) and qPCR was performed to detect the EBV-EBNA-1 gene region. Cohen's kappa index and the chi-square test were used to compare the methodologies and investigate correlations with the clinical-pathological data of the gastric adenocarcinoma patients. Most of the patients were men, and the average age was 60 years. The intestinal subtype cancer presented more aggressive stages with 90% of patients having a reactive FISH for EBV (EBV+), although the virus infection frequency in epithelial gastric tissue was only 1%. No positive association with clinicopathological features and EBV+ was found by FISH. Using qPCR analysis, the percentage of positive samples was lower (52.4%), and a positive association was found in samples from older patients (> 60 years). Interestingly, 71 qPCR-negative cases were detected by FISH in the presence of non-epithelial cells and in 10 qPCR-positive cases with no evidence of EBV according to FISH. The concordance between the two techniques was low, with only 57.6%. FISH is more informative for associating the gastric carcinoma with EBV positivity in tumor/epithelial cells; however, qPCR can provide relevant information regarding the progression and characteristics of neoplasia.

Epstein-Barr virus associated gastric dysplasia: a new rare entity?

Epstein-Barr virus (EBV) infection characterizes a portion of gastric adenocarcinomas. However, since there is lack of evidence of EBV presence in pre-neoplastic lesions of gastric mucosa, the etiologic role of EBV in gastric carcinogenesis is still debated. We report an unusual case of an EBV-associated foveolar gastric dysplasia associated with a focus of EBV-positive low-grade tubular adenocarcinoma, arisen in the context of a lymphocytic-like (EBV-positive) gastritis. The present case offers the unique opportunity to determine whether EBV is an early or late event in gastric cancer development and to evaluate its prevalence in patients with gastric dysplasia. To properly address this question, we investigated EBER expression in a large mono-institutional series of gastric and gastro-esophageal cancers (n = 594) and associated precursor lesions (n = 84). All the selected gastric dysplastic lesions (n = 43) resulted EBV negative. In most cases, EBV is present only in gastric and gastroesophageal junction adenocarcinomas, but not in their precursor lesions. However, the reported case indicates that non-conventional EBV-associated dysplasia may represent a novel histopathological entity in the gastric dysplasia scenario and that EBV could play an early direct role in gastric carcinogenesis.

Current prognostic and predictive biomarkers for gastrointestinal tumors in clinical practice

The pathologist emerged in the personalized medicine era as a central actor in the definition of the most adequate diagnostic and therapeutic algorithms. In the last decade, gastrointestinal oncology has seen a significantly increased clinical request for the integration of novel prognostic and predictive biomarkers in histopathological reports. This request couples with the significant contraction of invasive sampling of the disease, thus conferring to the pathologist the role of governor for both proper pathologic characterization and customized processing of the biospecimens. This overview will focus on the most commonly adopted immunohistochemical and molecular biomarkers in the routine clinical characterization of gastrointestinal neoplasms referring to the most recent published recommendations, guidelines and expert opinions.

Identification of anti-Epstein-Barr virus (EBV) antibody signature in EBV-associated gastric carcinoma

BACKGROUND

Around 10% of gastric carcinomas (GC) contain Epstein-Barr virus (EBV) DNA. We characterized the GC-specific antibody response to this common infection, which may provide a noninvasive method to detect EBV-positive GC and elucidate its contribution to carcinogenesis.

METHODS

Plasma samples from EBV-positive (n = 28) and EBV-negative (n = 34) Latvian GC patients were immune-profiled against 85 EBV proteins on a multi-microbial Nucleic Acid Programmable Protein Array (EBV-NAPPA). Antibody responses were normalized for each sample as ratios to the median signal intensity (MNI) across all antigens, with seropositivity defined as MNI ≥ 2. Antibodies with ≥ 20% sensitivity at 95% specificity for tumor EBV status were verified by enzyme-linked immunosorbent assay (ELISA) and validated in independent samples from Korea and Poland (n = 24 EBV-positive, n = 65 EBV-negative).

RESULTS

Forty anti-EBV IgG and eight IgA antibodies were detected by EBV-NAPPA in ≥ 10% of EBV-positive or EBV-negative GC patients, of which nine IgG antibodies were discriminative for tumor EBV status. Eight of these nine were verified and seven were validated by ELISA: anti-LF2 (odds ratio = 110.0), anti-BORF2 (54.2), anti-BALF2 (44.1), anti-BaRF1 (26.7), anti-BXLF1 (12.8), anti-BRLF1 (8.3), and anti-BLLF3 (5.4). The top three had areas under receiver operating characteristics curves of 0.81-0.85 for distinguishing tumor EBV status.

CONCLUSIONS

The EBV-associated GC-specific humoral response was exclusively directed against lytic cycle immediate-early and early antigens, unlike other EBV-associated malignancies such as nasopharyngeal carcinoma and lymphoma where humoral response is primarily directed against late lytic antigens. Specific anti-EBV antibodies could have utility for clinical diagnosis, epidemiologic studies, and immune-based precision treatment of EBV-positive GC.

Collagenous Gastritis in Primary Selective IgM Deficiency: Transition to EBV+ Gastric Adenocarcinoma

Selective IgM deficiency (SIgMD) and isolated collagenous gastritis are two independent rare disorders. Our purpose is to report the 1^st case of SIgMD and isolated collagenous gastritis and collagenous gastritis that has transitioned to EBV + gastric adenocarcinoma. Gastric biopsy tissue was analyzed by EBV-related encoded RNA in situ hybridization assay. Subsets of CD4, CD8, T follicular helper cells (T_FH), and members of the “regulatory lymphocytes club” were measured with multiple panels of monoclonal antibodies and isotype controls by multicolor flow cytometry. The patient was diagnosed with SIgMD (extremely low serum IgM 9 mg/dl and normal IgG and IgA and exclusion of secondary causes of low IgM). Soon after SIgMD diagnosis, the patient developed collagenous gastritis and, 8 years later, developed gastric adenocarcinoma that was positive for EBV. An extensive immunological analysis revealed reduced naïve CD4 and CD8 effector memory T cells and increased naïve and central memory CD8 T cells. Among the circulating follicular helper T cells (cT_FH), T_FH1 and T_FH2 were increased whereas T_FH17 was decreased. CD4 Treg cells and T_FR cells were increased, whereas Breg and CD8 Treg were comparable to control. In conclusion, SIgMD may be associated with isolated collagenous gastritis, and collagenous gastritis may transition to EBV + gastric adenocarcinoma. A role of regulatory lymphocytes in gastric cancer is discussed.

Association between Epstein-Barr virus infection and gastric cancer: a systematic review and meta-analysis

BACKGROUND

Numerous studies conducted over the past 30 years have pointed to the presence of Epstein-Barr virus (EBV) in gastric cancer samples. This study was aimed to provide a meta-analytic review of the prevalence of EBV in gastric cancer patients, and to clarify the relationship between EBV infection and gastric cancer.

METHODS

A literature search was performed electronically using online databases for English language publications until July 1, 2019. The pooled EBV prevalence and 95% confidence intervals (CIs) were estimated using a random-effects model. To determine the association between EBV and gastric cancer, pooled odds ratio (OR) and its 95% CI were computed for case-control studies. Two separate analyses were performed on data from case-control studies with matched and non-match pairs designs to calculate the pooled estimates of ORs.

RESULTS

The pooled prevalence of EBV in 20,361 gastric cancer patients was 8.77% (95% CI: 7.73-9.92%; I² = 83.2%). There were 20 studies with matched pairs design, including tumor and tumor-adjacent normal tissue pairs from 4116 gastric cancer patients. The pooled ORs were 18.56 (95% CI: 15.68-21.97; I² = 55.4%) for studies with matched pairs design and 3.31 (95% CI: 0.95-11.54; I² = 55.0%) for studies with non-matched pairs design. The proportion of EBV-associated gastric cancer among male cases was significantly higher than among female cases (10.83%, vs. 5.72%) (P < 0.0001). However, the pooled OR estimate for EBV-associated gastric cancer was significantly higher among females (21.47; 95% CI: 15.55-29.63; I² = 0%) than in males (14.07; 95% CI: 10.46-18.93; I² = 49.0%) (P = 0.06). EBV was more prevalent in the cardia (12.47%) and the body (11.68%) compared to the antrum (6.29%) (P = 0.0002).

CONCLUSIONS

EBV infection is associated with more than 18 times increase the risk of gastric cancer. Although the prevalence of EBV was higher in male patients than in female patients with gastric cancer, women are more likely than men to develop EBV-associated gastric cancer. Our findings showed that using tumor-adjacent normal tissues as the control group provides more robust and accurate results regarding the relationship between EBV infection and gastric cancer.

Positive Status of Epstein-Barr Virus as a Biomarker for Gastric Cancer Immunotherapy: A Prospective Observational Study

Immunotherapy has exhibited promising but controversial results in gastric cancer; determining criteria for choosing the appropriate target population is still problematic. Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) exhibits distinctive genomic aberrations and clinicopathologic features, the positive status of EBV is a potential biomarker. We prospectively recruited 9 patients who were diagnosed with stage-IV EBVaGC, and all of the patients were treated by immune-checkpoint inhibitors. The median age of the patients was 62 years old. The clinicopathologic characteristics demonstrated a male predominance and poor differentiation status of EBVaGC. Lymph nodes were demonstrated to represent the most common metastatic site. Immunochemistry and polymerase chain reaction analysis revealed that all of the patients were proficient mismatch repair, and microsatellite instability-stable and programmed cell death-ligand 1 were detected in 7 patients. Three patients with positive programmed cell death-ligand 1 showed partial response, 5 patients showed stable disease, 1 patient without measurable lesion showed decreasing ascites and tumor marker level after immunotherapy. The longest duration of response was 18 months by the time of the last follow-up. EBVaGC exhibits distinctive clinicopathologic characteristics, and EBV-positive status may be a potential biomarker for gastric cancer immunotherapy.

Circulating Antibodies against Epstein-Barr Virus (EBV) and p53 in EBV-Positive and -Negative Gastric Cancer

BACKGROUND

Epstein-Barr virus (EBV)-positive gastric cancers have clinicopathologic differences from EBV-negative tumors and lack TP53 mutation. Serologic profiles may inform viral contribution to carcinogenesis.

METHODS

We compared humoral responses of EBV-positive (n = 67) and EBV-negative (n = 137) patients with gastric cancer from the International EBV-Gastric Cancer Consortium. Serum antibodies against four EBV proteins, nuclear (EBNA), viral capsid (VCA), early-diffuse (EA-D), and Zta replication activator (ZEBRA), and to p53 were assessed by multiplex assays. OR of antibody level tertiles (T1-T3) were adjusted by logistic regression. We also conducted a meta-analysis of reported anti-p53 seropositivity in gastric cancer.

RESULTS

Consistent with EBV's ubiquity, 99% of patients were seropositive for anti-EBNA and 98% for anti-VCA, without difference by tumor EBV status. Seropositivity varied between patients with EBV-positive and EBV-negative tumors for anti-EA-D (97% vs. 67%, respectively, P < 0.001) and anti-ZEBRA (97% vs. 85%, respectively, P = 0.009). Adjusted ORs (vs. T1) for patients with EBV-positive versus EBV-negative tumors were significantly elevated for higher antibodies against EBNA (2.6 for T2 and 13 for T3), VCA (1.8 for T2 and 2.4 for T3), EA-D (6.0 for T2 and 44 for T3), and ZEBRA (4.6 for T2 and 12 for T3). Antibodies to p53 were inversely associated with EBV positivity (3% vs. 15%; adjusted OR = 0.16, P = 0.021). Anti-p53 prevalence from the literature was 15%.

CONCLUSIONS

These serologic patterns suggest viral reactivation in EBV-positive cancers and identify variation of p53 seropositivity by subtype.

IMPACT

Anti-EBV and anti-p53 antibodies are differentially associated with tumor EBV positivity. Serology may identify EBV-positive gastric cancer for targeted therapies.

Virus expression detection reveals RNA-sequencing contamination in TCGA

BACKGROUND

Contamination of reagents and cross contamination across samples is a long-recognized issue in molecular biology laboratories. While often innocuous, contamination can lead to inaccurate results. Cantalupo et al., for example, found HeLa-derived human papillomavirus 18 (H-HPV18) in several of The Cancer Genome Atlas (TCGA) RNA-sequencing samples. This work motivated us to assess a greater number of samples and determine the origin of possible contaminations using viral sequences. To detect viruses with high specificity, we developed the publicly available workflow, VirDetect, that detects virus and laboratory vector sequences in RNA-seq samples. We applied VirDetect to 9143 RNA-seq samples sequenced at one TCGA sequencing center (28/33 cancer types) over 5 years.

RESULTS

We confirmed that H-HPV18 was present in many samples and determined that viral transcripts from H-HPV18 significantly co-occurred with those from xenotropic mouse leukemia virus-related virus (XMRV). Using laboratory metadata and viral transcription, we determined that the likely contaminant was a pool of cell lines known as the "common reference", which was sequenced alongside TCGA RNA-seq samples as a control to monitor quality across technology transitions (i.e. microarray to GAII to HiSeq), and to link RNA-seq to previous generation microarrays that standardly used the "common reference". One of the cell lines in the pool was a laboratory isolate of MCF-7, which we discovered was infected with XMRV; another constituent of the pool was likely HeLa cells.

CONCLUSIONS

Altogether, this indicates a multi-step contamination process. First, MCF-7 was infected with an XMRV. Second, this infected cell line was added to a pool of cell lines, which contained HeLa. Finally, RNA from this pool of cell lines contaminated several TCGA tumor samples most-likely during library construction. Thus, these human tumors with H-HPV or XMRV reads were likely not infected with H-HPV 18 or XMRV.

Clinicopathological characteristics of Epstein-Barr virus-positive gastric cancer in Latvia

OBJECTIVE

Epstein-Barr virus (EBV)-associated gastric cancer has been proposed to be a distinct gastric cancer molecular subtype. The prognostic significance of EBV infection in gastric cancer remains unclear and needs further investigation. Our study aimed to analyze EBV-positive and EBV-negative gastric cancer patients regarding their personal and tumor-related characteristics, and compare their overall survival.

METHODS

Gastric cancer patients consecutively treated at the Riga East University Hospital during 2009-2016 were identified retrospectively. Tumor EBV status was determined by in-situ hybridization for EBV-encoded RNA (EBER). Information about clinicopathological characteristics was obtained from patient questionnaires, hospital records. Overall survival was ascertained through 30 July 2017. Cox proportional hazard regression models adjusted for personal and tumor-related covariates compared survival between EBV-positive and EBV-negative patients.

RESULTS

There were a total of 302 gastric cancer patients (61% males) with mean and SD age 63.6 ± 11.5 years. EBER positivity was present in 8.6% of tumors. EBV-positive gastric cancer patients had better survival at 80 months [adjusted hazard ratio = 0.37, 95% confidence interval (CI) = 0.19-0.72] compared to EBV-negative patients. Worse survival was observed for patients with stage III (hazard ratio = 2.76, 95% CI = 1.67-4.56) and stage IV (hazard ratio = 10.02, 95% CI = 5.72-17.57) compared to stage I gastric cancer, and overlapping and unspecified subsite (hazard ratio = 1.85; 95% CI = 1.14; 3.00) compared to distal tumors.

CONCLUSION

Tumor EBV positivity is a favorable prognostic factor in gastric cancer.

Novel Therapeutics for Epstein⁻Barr Virus

Epstein–Barr virus (EBV) is a human γ-herpesvirus that infects up to 95% of the adult population. Primary EBV infection usually occurs during childhood and is generally asymptomatic, though the virus can cause infectious mononucleosis in 35–50% of the cases when infection occurs later in life. EBV infects mainly B-cells and epithelial cells, establishing latency in resting memory B-cells and possibly also in epithelial cells. EBV is recognized as an oncogenic virus but in immunocompetent hosts, EBV reactivation is controlled by the immune response preventing transformation in vivo. Under immunosuppression, regardless of the cause, the immune system can lose control of EBV replication, which may result in the appearance of neoplasms. The primary malignancies related to EBV are B-cell lymphomas and nasopharyngeal carcinoma, which reflects the primary cell targets of viral infection in vivo. Although a number of antivirals were proven to inhibit EBV replication in vitro, they had limited success in the clinic and to date no antiviral drug has been approved for the treatment of EBV infections. We review here the antiviral drugs that have been evaluated in the clinic to treat EBV infections and discuss novel molecules with anti-EBV activity under investigation as well as new strategies to treat EBV-related diseases.

Viral loads correlate with upregulation of PD-L1 and worse patient prognosis in Epstein-Barr Virus-associated gastric carcinoma

Epstein–Barr virus (EBV)-associated gastric carcinoma (EBVaGC), one of four major gastric cancer types, consists of clonal growth of EBV-infected epithelial cells. However, the significance of viral loads in each tumor cell has not been evaluated. EBV-DNA is stably maintained in episomal form in the nucleus of each cancer cell. To estimate EBV copy number per genome (EBV-CN), qPCR of viral EBNA1 and host GAPDH, standardized by Namalwa DNA (one copy/genome), was applied to the formalin-fixed paraffin embedded (FFPE) surgically resected EBVaGC specimens (n = 43) and EBVaGC cell lines (SNU-719 and NCC-24). In surgical specimens, the cancer cell ratio (CCR) was determined with image analysis, and EBV-CN was obtained by adjusting qPCR value with CCR. Fluorescent in situ hybridization (FISH) was also applied to the FFPE sections using the whole EBV-genome as a probe. In surgical specimens, EBV-CN obtained by qPCR/CCR was between 1.2 and 185 copies with a median of 9.9. EBV-CN of SNU-719 and NCC-24 was 42.0 and 1.1, respectively. A linear correlation was observed with qPCR/CCR data up to 20 copies/genome (40 signals/nucleus), the limit of FISH analysis. In addition, substantial variation in the number of EBV foci was observed. Based on qPCR/CCR, high EBV-CN (>10 copies) correlated with PD-L1 expression in cancer cells (P = 0.015), but not with other pathological indicators. Furthermore, EBVaGC with high EBV-CN showed worse disease-specific survival (P = 0.041). Our findings suggest that cancer cell viral loads may contribute to expression of the immune checkpoint molecule and promotion of cancer progression in EBVaGC.

Epstein-Barr Virus-Positive Cancers Show Altered B-Cell Clonality

Around 20% of human cancers are associated with viruses. Epstein-Barr virus (EBV) contributes to gastric cancer, nasopharyngeal carcinoma, and certain lymphomas, but its role in other cancer types remains controversial. We assessed the prevalence of EBV in RNA-seq from 32 tumor types in the Cancer Genome Atlas Project (TCGA) and found EBV to be present in >5% of samples in 12 tumor types. EBV infects epithelial cells and B cells and in B cells causes proliferation. We hypothesized that the low expression of EBV in most of the tumor types was due to infiltration of B cells into the tumor. The increase in B-cell abundance and diversity in subjects where EBV was detected in the tumors strengthens this hypothesis. Overall, we found that EBV was associated with an increased and altered immune response. This result is not evidence of causality, but a potential novel biomarker for tumor immune status.

Epstein-Barr virus (EBV) is convincingly associated with gastric cancer, nasopharyngeal carcinoma, and certain lymphomas, but its role in other cancer types remains controversial. To test the hypothesis that there are additional cancer types with high prevalence of EBV, we determined EBV viral expression in all the Cancer Genome Atlas Project (TCGA) mRNA sequencing (mRNA-seq) samples (n = 10,396) from 32 different tumor types. We found that EBV was present in gastric adenocarcinoma and lymphoma, as expected, and was also present in >5% of samples in 10 additional tumor types. For most samples, EBV transcript levels were low, which suggests that EBV was likely present due to infected infiltrating B cells. In order to determine if there was a difference in the B-cell populations, we assembled B-cell receptors for each sample and found B-cell receptor abundance (P ≤ 1.4 × 10⁻²⁰) and diversity (P ≤ 8.3 × 10⁻²⁷) were significantly higher in EBV-positive samples. Moreover, diversity was independent of B-cell abundance, suggesting that the presence of EBV was associated with an increased and altered B-cell population.

IMPORTANCE Around 20% of human cancers are associated with viruses. Epstein-Barr virus (EBV) contributes to gastric cancer, nasopharyngeal carcinoma, and certain lymphomas, but its role in other cancer types remains controversial. We assessed the prevalence of EBV in RNA-seq from 32 tumor types in the Cancer Genome Atlas Project (TCGA) and found EBV to be present in >5% of samples in 12 tumor types. EBV infects epithelial cells and B cells and in B cells causes proliferation. We hypothesized that the low expression of EBV in most of the tumor types was due to infiltration of B cells into the tumor. The increase in B-cell abundance and diversity in subjects where EBV was detected in the tumors strengthens this hypothesis. Overall, we found that EBV was associated with an increased and altered immune response. This result is not evidence of causality, but a potential novel biomarker for tumor immune status.

Associations of Epstein-Barr Virus-Positive Gastric Adenocarcinoma with Circulating Mediators of Inflammation and Immune Response

Epstein-Barr virus (EBV)-positive gastric adenocarcinoma exhibits locally intense inflammation but systemic manifestations are uncertain. Our study examined whether circulating mediators of inflammation and immune response differ by tumor EBV status. From a Latvian series of 302 gastric cancer cases, we measured plasma levels of 92 immune-related proteins in the 28 patients with EBV-positive tumors and 34 patients with EBV-negative tumors. Eight markers were statistically significantly higher with tumor EBV positivity: chemokine C-C motif ligand (CCL) 20 (Odds Ratio (OR) = 3.6; p-trend = 0.001), chemokine C-X-C motif ligand 9 (OR = 3.6; p-trend = 0.003), programmed death-ligand 1 (PD-L1; OR = 3.4; p-trend = 0.004), interleukin (IL)-10 (OR = 2.4; p-trend = 0.019), CCL19 (OR = 2.3; p-trend = 0.019), CCL11 (OR = 2.2; p-trend = 0.026), IL-17A (OR = 2.0; p-trend = 0.038) and CCL8 (OR = 1.9; p-trend = 0.049). Systemic responses to EBV-positive gastric cancer are characterized by alterations in chemokines and PD-L1. Profiling of these molecules may enable non-invasive diagnosis of EBV status when tumor tissue is unavailable. Our findings provide theoretical justification for clinical evaluations of immune checkpoint therapy for EBV-positive gastric cancer.

Clinical utility of circulating cell-free Epstein-Barr virus DNA in patients with gastric cancer

Recent comprehensive molecular subtyping of gastric cancer (GC) identified Epstein-Barr virus (EBV)-positive tumors as a subtype with distinct salient molecular and clinical features. In this study, we aimed to determine the potential utility of circulating cell-free EBV DNA as a biomarker for the detection and/or monitoring of therapeutic response in patients with EBV-associated gastric carcinoma (EBVaGC). The EBV genes-to-ribonuclease P RNA component H1 ratios (EBV ratios) in the GC tumors and plasma samples were determined by quantitative real-time polymerase chain reaction in 153 patients with GC, including 14 patients with EBVaGC diagnosed by the conventional method. Circulating cell-free EBV DNA was detected in 14 patients with GC: the sensitivity and specificity of detection were 71.4% (10/14) and 97.1% (135/139), respectively. Plasma EBV ratios were significantly correlated with the size of EBVaGC tumors, and the plasma EBV DNA detected before surgery in EBVaGC cases disappeared after surgery. Patients with EBVaGC may have a better prognosis, but circulating cell-free EBV DNA had no or little impact on prognosis. In addition, repeated assessment of the plasma EBV ratio in EBVaGC showed a decrease and increase in plasma EBV DNA after treatment and during tumor progression/recurrence, respectively. These results suggest the potential utility of circulating cell-free DNA to reveal EBV DNA for the identification of the EBVaGC subtype and/or for real-time monitoring of tumor progression as well as treatment response in patients with EBVaGC.

A viral map of gastrointestinal cancers

Cancers of the gastrointestinal tract (GIT) are expected to account for approximately 20% of all cancers in 2017. Apart from their high incidence, GIT cancers show high mortality rates, placing these malignancies among the most prominent public health issues of our time. Cancers of the GIT are the result of a complex interplay between host genetic factors and environmental factors and frequently arise in the context of a continued active inflammatory response. Several tumor viruses are able to elicit such chronic inflammatory responses. In fact, several viruses have an impact on GIT tumor initiation and progression, as well as on patients' response to therapy and prognosis, through direct and indirect mechanisms. In this review, we have gathered information on different viruses' rates of infection, viral-driven specific carcinogenesis mechanisms and viral-related impact on the prognosis of cancers of the GIT (specifically in organs that have an interface with the environment - esophagus, stomach, intestines and anus). Overall, while some viral infections show a strong causal relation with specific gastrointestinal cancers, these represent a relatively small fraction of GIT malignancies. Other types of cancer, like Esophageal Squamous Cell Carcinoma, require further studies to confirm the carcinogenic role of some viral agents.

Elevated Levels of Interferon-γ Are Associated with High Levels of Epstein-Barr Virus Reactivation in Patients with the Intestinal Type of Gastric Cancer

Background

The inflammatory response directed against Helicobacter pylori (HP) is believed to be one of the main triggers of the appearance of gastric lesions and their progression to gastric cancer (GC). Epstein-Barr virus (EBV) has been found responsible for about 10% of all GCs, but the inflammatory response has not been studied in GC patients with evidence of high levels of EBV reactivation.

Objective

To determine the relationship between inflammation and antibodies against EBV reactivation antigens, HP, and the bacterium virulence factor CagA in patients with GC.

Methods

127 GC patients, 46 gastritis patients, and 197 healthy subjects were studied. IL-1β, IL-6, IL-8, IL-10, TNF-α, TGF-β, MCP-1, and IFN-γ levels were measured in serum or plasma and compared against the antibody titers of VCA-IgG, HP, and the HP virulence factor CagA. Statistical associations were estimated.

Results

Significant ORs and positive trends were found between VCA-IgG and IFN-γ, specifically for patients with GC of intestinal type (OR: 6.4, 95% C.I. 1.2–35.4) (p < 0.044).

Conclusions

We confirmed a positive association between a marker of EBV reactivation and intestinal gastric cancer and present evidence of a correlation with elevated serum levels of IFN-γ, but not with the other cytokines.

Clinical and pathological characterization of Epstein-Barr virus-associated gastric carcinomas in Portugal

AIM

To determine the prevalence of Epstein-Barr virus (EBV)-associated gastric carcinomas in the North Region of Portugal and to study its clinicopathological characteristics.

METHODS

We have performed a retrospective study including a total of 179 consecutive patients with gastric cancer (GC) submitted to gastrectomy during 2011 at the Portuguese Oncology Institute of Porto. Clinical and pathological data was collected from individual clinical records and inserted on a database with unique codification. Tumour tissues were collected from the institutional tumour bank. EBV was detected by in situ hybridization for the detection of EBV-encoded small RNAs (EBERs) and EBV latent proteins (LMP1 and LMP2A) were detected by immunohistochemistry.

RESULTS

The analysis showed that EBV-associated gastric carcinomas (EBVaGC) represents 8.4% (15/179) of all GC cases, with a significant differential distribution among histological types (P < 0.001): 100% (3/3) of medullary carcinomas, 100% (1/1) of adenosquamous carcinoma, 8.7% (8/92) of tubular adenocarcinomas, 8.0% (2/25) of mixed carcinomas and 2% (1/51) in poorly cohesive carcinomas. The analysis revealed a higher predominance of EBVaGC in the upper third and middle (cardia, fundus and body) of the stomach (P = 0.041), a significant lower number of regional lymph nodes invasion (P = 0.025) and a tendency for better prognosis (P = 0.222). EBV latent protein expression revealed that all EBVaGC cases were LMP1-negative, nevertheless 6 cases (40%) expressed LPM2A, which reveals that these cases show a distinct EBV-Latency profile (latency II-like).

CONCLUSION

EBVaGC represents 8.4% of all GC in the North Region of Portugal. The EBV-infected patients have specific clinic-pathological features that should be further explored to develop new strategies of management and treatment.

The conundrum of the Epstein-Barr virus-associated gastric carcinoma in the Americas

Epstein-Barr virus-associated gastric carcinoma shows a higher prevalence in the Americas than Asia. We summarize all studies of Epstein Barr virus-associated gastric carcinoma in the Americas, focusing on host characteristics, environmental associations and phylogeographic diversity of Epstein-Barr virus strains. In the Americas, the prevalence of Epstein Barr virus-associated gastric carcinoma is 11.4%, more frequent in males and portray predominantly diffuse-type histology. EBERs, EBNAs, BARTs and LMP are the highest expressed genes; their variations in healthy individuals may explain the phylogeographic diversity of Epstein-Barr virus across the region. Gastric cancer cases harbor exclusively the western genotype (subtype D and kept Xho I site), suggesting a disrupted co-evolution between the pathogen and its host. Epstein-Barr virus-associated gastric carcinoma molecular subtype cases from The Cancer Genome Atlas display PIK3CA gene mutations, amplification of JAK2, PD-L1 and PD-L2 and CpG island methylator phenotype, leading to more extensive methylation of host and viral genomes than any other subtypes from the study. Environmental conditions include negative- and positive- associations with being firstborn child and smoking, respectively. A marginal association with H. pylori has also been reported. Lymphoepithelioma-like carcinoma is associated with Epstein Barr virus in 80%-86% of cases, most of which have been included as part of Epstein Barr virus-associated gastric carcinoma series (prevalence 1.1%-7.6%). Whether these cases represent a variant of Epstein-Barr virus-associated gastric carcinoma is discussed. We propose novel research strategies to solve the conundrum of the high prevalence of Epstein-Barr virus-associated gastric carcinoma in the Americas.

The impact of targeting repetitive BamHI-W sequences on the sensitivity and precision of EBV DNA quantification

Background

Viral load monitoring and early Epstein-Barr virus (EBV) DNA detection are essential in routine laboratory testing, especially in preemptive management of Post-transplant Lymphoproliferative Disorder. Targeting the repetitive BamHI-W sequence was shown to increase the sensitivity of EBV DNA quantification, but the variability of BamHI-W reiterations was suggested to be a source of quantification bias. We aimed to assess the extent of variability associated with BamHI-W PCR and its impact on the sensitivity of EBV DNA quantification using the 1st WHO international standard, EBV strains and clinical samples.

Methods

Repetitive BamHI-W- and LMP2 single- sequences were amplified by in-house qPCRs and BXLF-1 sequence by a commercial assay (EBV R-gene™, BioMerieux). Linearity and limits of detection of in-house methods were assessed. The impact of repeated versus single target sequences on EBV DNA quantification precision was tested on B95.8 and Raji cell lines, possessing 11 and 7 copies of the BamHI-W sequence, respectively, and on clinical samples.

Results

BamHI-W qPCR demonstrated a lower limit of detection compared to LMP2 qPCR (2.33 log₁₀ versus 3.08 log₁₀ IU/mL; P = 0.0002). BamHI-W qPCR underestimated the EBV DNA load on Raji strain which contained fewer BamHI-W copies than the WHO standard derived from the B95.8 EBV strain (mean bias: - 0.21 log₁₀; 95% CI, -0.54 to 0.12). Comparison of BamHI-W qPCR versus LMP2 and BXLF-1 qPCR showed an acceptable variability between EBV DNA levels in clinical samples with the mean bias being within 0.5 log₁₀ IU/mL EBV DNA, whereas a better quantitative concordance was observed between LMP2 and BXLF-1 assays.

Conclusions

Targeting BamHI-W resulted to a higher sensitivity compared to LMP2 but the variable reiterations of BamHI-W segment are associated with higher quantification variability. BamHI-W can be considered for clinical and therapeutic monitoring to detect an early EBV DNA and a dynamic change in viral load.

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.

Epstein-Barr virus gene expression and latency pattern in gastric carcinomas: a systematic review

METHODS

A systematic review of literature was conducted to identify all published reports regarding the expression of Epstein-Barr Virus (EBV) proteins/transcripts and EBV latency patterns in EBV-associated gastric carcinomas (EBVaGC).

RESULTS

The literature search retrieved 247 papers, of which 25 papers matched the inclusion criteria. The analysis reveals that the most frequently expressed EBV latent proteins are EBNA1 (98.1%) and LMP2A (53.8%), while LMP1 and LMP2B are present in only 10% of cases. Lytic proteins, such as BARF0 and BARF1, and other lytic transcripts are present in almost half of cases.

CONCLUSION

EBVaGC seems to display a unique transcription/latency pattern that does not fit the 'standard' EBV latency patterns and therefore should be further studied to better understand EBVaGC carcinogenesis.

Three Molecular Subtypes of Gastric Adenocarcinoma Have Distinct Histochemical Features Reflecting Epstein-Barr Virus Infection Status and Neuroendocrine Differentiation

Current histopathologic classification schemes for gastric adenocarcinoma have limited clinical utility and are difficult to apply due to tumor heterogeneity. Elucidation of molecular subtypes of gastric cancer may contribute to our understanding of gastric cancer biology and to the development of new molecular markers that may lead to improved diagnosis, therapy, or prognosis. We previously demonstrated that Epstein-Barr virus (EBV)-infected gastric cancers have a distinct human gene expression profile compared with uninfected cancers. We now examine the histopathologic features characterizing infected (n=14) and uninfected (n=89) cancers; the latter of which are now further divided into 2 major molecular subtypes based on expression patterns of 93 RNAs. One uninfected gastric cancer subtype was distinguished by upregulation of 3 genes with neuroendocrine (NE) function (CHGA, GAST, and REG4 encoding chromogranin, gastrin, and the secreted peptide REG4 involved in epithelial cell regeneration), implicating hormonal factors in the pathogenesis of a major class of gastric adenocarcinomas. Evidence of NE differentiation (molecular, immunohistochemical, or morphologic) was mutually exclusive of EBV infection. EBV-infected tumors tended to have solid-type morphology with lymphoid stroma. This study reveals novel molecular subtypes of gastric cancer and their associated morphologies that demonstrate divergent NE features.

Gastric adenocarcinoma microRNA profiles in fixed tissue and in plasma reveal cancer-associated and Epstein-Barr virus-related expression patterns

MicroRNA expression in formalin-fixed paraffin-embedded tissue (FFPE) or plasma may add value for cancer management. The GastroGenus miR Panel was developed to measure 55 cancer-specific human microRNAs, Epstein-Barr virus (EBV)-encoded microRNAs, and controls. This Q-rtPCR panel was applied to 100 FFPEs enriched for adenocarcinoma or adjacent non-malignant mucosa, and to plasma of 31 patients. In FFPE, microRNAs upregulated in malignant versus adjacent benign gastric mucosa were hsa-miR-21, -155, -196a, -196b, -185, and -let-7i. Hsa-miR-18a, 34a, 187, -200a, -423-3p, -484, and -744 were downregulated. Plasma of cancer versus non-cancer controls had upregulated hsa-miR-23a, -103, and -221 and downregulated hsa-miR-378, -346, -486-5p, -200b, -196a, -141, and -484. EBV-infected versus uninfected cancers expressed multiple EBV-encoded microRNAs, and concomitant dysregulation of four human microRNAs suggests that viral infection may alter cellular biochemical pathways. Human microRNAs were dysregulated between malignant and benign gastric mucosa and between plasma of cancer patients and non-cancer controls. Strong association of EBV microRNA expression with known EBV status underscores the ability of microRNA technology to reflect disease biology. Expression of viral microRNAs in concert with unique human microRNAs provides novel insights into viral oncogenesis and reinforces the potential for microRNA profiles to aid in classifying gastric cancer subtypes. Pilot studies of plasma suggest the potential for a noninvasive addition to cancer diagnostics.

Validation and calibration of next-generation sequencing to identify Epstein-Barr virus-positive gastric cancer in The Cancer Genome Atlas

The Epstein-Barr virus (EBV)-positive subtype of gastric adenocarcinoma is conventionally identified by in situ hybridization (ISH) for viral nucleic acids, but next-generation sequencing represents a potential alternative. We therefore determined normalized EBV read counts by whole-genome, whole-exome, mRNA and miRNA sequencing for 295 fresh-frozen gastric tumor samples. Formalin-fixed, paraffin-embedded tissue sections were retrieved for ISH confirmation of 13 high-EBV and 11 low-EBV cases. In pairwise comparisons, individual samples were either concordantly high or concordantly low by all genomic methods for which data were available. Empiric cutoffs of sequencing counts identified 26 (9 %) tumors as EBV positive. EBV positivity or negativity by molecular testing was confirmed by EBER-ISH in all but one tumor evaluated by both approaches (kappa = 0.91). EBV-positive gastric tumors can be accurately identified by quantifying viral sequences in genomic data. Simultaneous analyses of human and viral DNA, mRNA and miRNA could streamline tumor profiling for clinical care and research.

Anti-Helicobacter pylori Antibody Profiles in Epstein-Barr virus (EBV)-Positive and EBV-Negative Gastric Cancer

BACKGROUND

Helicobacter pylori is the primary cause of gastric cancer, but about 9% of cases harbor Epstein-Barr virus (EBV) in the tumor cells. There is limited evidence on the possible interaction or antagonism between these infectious agents in gastric carcinogenesis.

METHODS

We compared H. pylori serologic profiles of EBV-positive (n = 58) and EBV-negative (n = 111) noncardia gastric cancer patients from the United States National Cancer Institute's International EBV-Gastric Cancer Consortium. EBV positivity of tumors was assessed by in situ hybridization. Serum levels of 15 antibodies to immunogenic proteins of H. pylori (Cad, CagA, Cagδ, CagM, Catalase, GroEL, HcpC, HP0231, HP0305, HpaA, HyuA, NapA, Omp, UreA, VacA) were assessed using bead-based multiplex serology. Logistic regression models were used to adjust odds ratios (OR) for country, age, sex, and year of diagnosis.

RESULTS

Seropositivity to individual proteins ranged up to 90% overall. Antibodies to Catalase were borderline associated with tumor EBV positivity (adjusted OR = 3.15, p = .0024, Bonferroni corrected p = .036). Distributions of other antibodies did not vary by tumor EBV status.

CONCLUSION

Similarity of host-response indicates the essential etiological role of H. pylori in EBV-positive gastric cancer.

Assessment of Epstein-Barr virus nucleic acids in gastric but not in breast cancer by next-generation sequencing of pooled Mexican samples

Gastric (GC) and breast (BrC) cancer are two of the most common and deadly tumours. Different lines of evidence suggest a possible causative role of viral infections for both GC and BrC. Wide genome sequencing (WGS) technologies allow searching for viral agents in tissues of patients with cancer. These technologies have already contributed to establish virus-cancer associations as well as to discovery new tumour viruses. The objective of this study was to document possible associations of viral infection with GC and BrC in Mexican patients. In order to gain idea about cost effective conditions of experimental sequencing, we first carried out an in silico simulation of WGS. The next-generation-platform IlluminaGallx was then used to sequence GC and BrC tumour samples. While we did not find viral sequences in tissues from BrC patients, multiple reads matching Epstein-Barr virus (EBV) sequences were found in GC tissues. An end-point polymerase chain reaction confirmed an enrichment of EBV sequences in one of the GC samples sequenced, validating the next-generation sequencing-bioinformatics pipeline.

Genomic assays for Epstein-Barr virus-positive gastric adenocarcinoma

A small set of gastric adenocarcinomas (9%) harbor Epstein–Barr virus (EBV) DNA within malignant cells, and the virus is not an innocent bystander but rather is intimately linked to pathogenesis and tumor maintenance. Evidence comes from unique genomic features of host DNA, mRNA, microRNA and CpG methylation profiles as revealed by recent comprehensive genomic analysis by The Cancer Genome Atlas Network. Their data show that gastric cancer is not one disease but rather comprises four major classes: EBV-positive, microsatellite instability (MSI), genomically stable and chromosome instability. The EBV-positive class has even more marked CpG methylation than does the MSI class, and viral cancers have a unique pattern of methylation linked to the downregulation of CDKN2A (p16) but not MLH1. EBV-positive cancers often have mutated PIK3CA and ARID1A and an amplified 9p24.1 locus linked to overexpression of JAK2, CD274 (PD-L1) and PDCD1LG2 (PD-L2). Multiple noncoding viral RNAs are highly expressed. Patients who fail standard therapy may qualify for enrollment in clinical trials targeting cancer-related human gene pathways or promoting destruction of infected cells through lytic induction of EBV genes. Genomic tests such as the GastroGenus Gastric Cancer Classifier are available to identify actionable variants in formalin-fixed cancer tissue of affected patients.

Detection and quantification of EBV, HHV-6 and CMV DNA in the gastrointestinal tract of HIV-positive patients

Human herpes viruses (HHVs) have been frequently detected in the gastrointestinal (GI) tract and may contribute to the development of gastric cancer. In the present study, the detection rate and viral load of Epstein Barr virus (EBV), HHV-6 and Cytomegalovirus (CMV) were assessed in the GI tract of human immunodeficiency virus (HIV) positive patients and of uninfected patients. The analysis revealed a significantly higher detection rate of EBV and HHV-6 in HIV-infected individuals than in uninfected subjects (88.5 vs 63%; p = 0.03). Moreover, EBV DNA load was significantly higher in the stomach of HIV patients than in controls. These data suggest that the HIV infection status may increase the persistence of these viruses in the GI compartment. Intriguingly, CMV DNA was undetectable in all biopsy specimens analyzed.

Case-case comparison of smoking and alcohol risk associations with Epstein-Barr virus-positive gastric cancer

Helicobacter pylori is the primary cause of gastric cancer. However, monoclonal Epstein-Barr virus (EBV) nucleic acid is also present in up to 10% of these tumors worldwide. EBV prevalence is increased with male sex, nonantral localization and surgically disrupted anatomy. To further examine associations between EBV and gastric cancer, we organized an international consortium of 11 studies with tumor EBV status assessed by in situ hybridization. We pooled individual-level data on 2,648 gastric cancer patients, including 184 (7%) with EBV-positive cancers; all studies had information on cigarette use (64% smokers) and nine had data on alcohol (57% drinkers). We compared patients with EBV-positive and EBV-negative tumors to evaluate smoking and alcohol interactions with EBV status. To account for within-population clustering, multilevel logistic regression models were used to estimate interaction odds ratios (OR) adjusted for distributions of sex (72% male), age (mean 59 years), tumor histology (56% Lauren intestinal-type), anatomic subsite (61% noncardia) and year of diagnosis (1983-2012). In unadjusted analyses, the OR of EBV positivity with smoking was 2.2 [95% confidence interval (CI) 1.6-3.2]. The OR was attenuated to 1.5 (95% CI 1.01-2.3) by adjustment for the possible confounders. There was no significant interaction of EBV status with alcohol drinking (crude OR 1.4; adjusted OR 1.0). Our data indicate the smoking association with gastric cancer is stronger for EBV-positive than EBV-negative tumors. Conversely, the null association with alcohol does not vary by EBV status. Distinct epidemiologic characteristics of EBV-positive cancer further implicate the virus as a cofactor in gastric carcinogenesis.

Improved survival of gastric cancer with tumour Epstein-Barr virus positivity: an international pooled analysis

BACKGROUND AND OBJECTIVE

About 9% of gastric carcinomas have Epstein-Barr virus (EBV) in the tumour cells, but it is unclear whether viral presence influences clinical progression. We therefore examined a large multicentre case series for the association of tumour EBV status with survival after gastric cancer diagnosis, accounting for surgical stage and other prognostic factors.

METHODS

We combined individual-level data on 4599 gastric cancer patients diagnosed between 1976 and 2010 from 13 studies in Asia (n=8), Europe (n=3), and Latin America (n=2). EBV positivity of tumours was assessed by in situ hybridisation. Mortality HRs for EBV positivity were estimated by Cox regression models stratified by study, adjusted for distributions of sex (71% male), age (mean 58 years), stage (52% tumour-node-metastasis stages III or IV), tumour histology (49% poorly differentiated, 57% Lauren intestinal-type), anatomic subsite (70% non-cardia) and year of diagnosis. Variations by study and continent were assessed using study-specific HRs for EBV positivity.

RESULTS

During median 3.0 years follow-up, 49% of patients died. Stage was strongly predictive of mortality, with unadjusted HRs (vs stage I) of 3.1 for stage II, 8.1 for stage III and 13.2 for stage IV. Tumour EBV positivity was 8.2% overall and inversely associated with stage (adjusted OR: 0.79 per unit change). Adjusted for stage and other confounders, EBV positivity was associated with lower mortality (HR, 0.72; 95% CI 0.61 to 0.86), with low heterogeneity among the study populations (p=0.2). The association did not significantly vary across patient or tumour characteristics. There was no significant variation among the three continent-specific HRs (p=0.4).

CONCLUSIONS

Our findings suggest that tumour EBV positivity is an additional prognostic indicator in gastric cancer. Further studies are warranted to identify the mechanisms underlying this protective association.

Evidence of Epstein-Barr virus association with gastric cancer and non-atrophic gastritis

Different lines of evidence support an association between Epstein-Barr virus (EBV) and gastric cancer (GC). The main understood risk factor to develop GC is infection by Helicobacter pylori (H. pylori), which triggers a local inflammatory response critical for progression from gastritis to GC. The role of EBV in early inflammatory gastric lesions has been poorly studied. A recent study proposed a cutoff value of 2000 EBV particles to identify patients with increased chances of infection of the gastric epithelium, which may favor the inflammatory process. To better understand the role of EBV in cancer progression, we analyzed 75 samples of GC, 147 control samples of non-tumor gastric tissue derived from GC patients and 75 biopsies from patients with non-atrophic gastritis (NAG). A first-round PCR was used for EBV detection in tumor and non-tumor controls and a more sensitive nested PCR for gastritis samples; both PCRs had lower detection limits above the proposed cutoff value. With this strategy 10.67% of GC, 1.3% of non-tumor controls and 8% of gastritis samples were found positive. An EBER1 in situ hybridization showed EBV infection of epithelial cells in GC and in a third of NAG samples, while in the other NAGs infection was restricted to the mononuclear cell infiltrate. EBV-positive GCs were enriched in lace and cribriform patterns, while these rare patterns were not observed in EBV negative samples. Our results support a role for EBV in GC and early precursor lesions, either as directly oncogenic infecting epithelial cells or indirectly as an inflammatory trigger.

Atypical Epstein-Barr viral genomic structure in lymphoma tissue and lymphoid cell lines

Epstein-Barr virus (EBV) DNA is found within the malignant cells of some subtypes of lymphoma, and viral presence is being exploited for improved diagnosis, monitoring, and management of affected patients. Recent work suggests that viral genomic polymorphism, such as partial deletion of the viral genome, could interfere with virus detection in tumor tissues. To test for atypical forms of the EBV genome, 98 lymphomas and 6 infected cell lines were studied using a battery of 6 quantitative polymerase chain reaction assays targeting disparate sections of EBV DNA. Fifty of the lymphomas (51%) had no amplifiable EBV DNA, and 38 lymphomas (39%) had low-level EBV infection that was deemed incidental based on EBV-encoded RNA (EBER) in situ hybridization results. The remaining 10 lymphomas (10%) had high EBV loads and EBER localization to malignant cells by EBER in situ hybridization. All 10 represented lymphoma subtypes were previously associated with EBV (Burkitt, diffuse large B-cell, or T-cell type), whereas no remnants of EBV were detected in other lymphoma subtypes (follicular, small lymphocytic, mantle cell, or marginal zone type). Interestingly, 4 of the 10 infected lymphomas had evidence of atypical viral genomes, including 3 of 4 infected T-cell lymphomas with aberrant loss of LMP2 amplicons, and a single diffuse large B-cell lymphoma lacking the central part of the viral genome spanning BamH1W, BZLF1, and EBNA1 gene segments. A reasonable screening strategy for infected malignancy involves applying EBER1 and LMP1 quantitative polymerase chain reaction assays and confirming that values exceeding 2000 copies of EBV per 100,000 cells have EBER localization to malignant cells.

Impact of Epstein-Barr virus load, virus genotype, and frequency of the 30 bp deletion in the viral BNLF-1 gene in patients harboring the human immunodeficiency virus

Patients infected with the human immunodeficiency virus (HIV) are at higher risk of developing Epstein-Barr Virus (EBV)-associated lymphomas. The usefulness of monitoring EBV in peripheral blood mononuclear cells (PBMCs) of patients infected with HIV has not been established. The aim of this study was to evaluate the EBV viral load in PBMCs, the frequency of viral genotypes, and the presence of the 30-bp deletion in the BNLF-1 gene. DNA samples from 156 patients attending the HIV/AIDS Day Clinic at Botucatu School of Medicine, Sao Paulo State University were evaluated. The EBV viral load was detectable by real time PCR in 123/156 (78.8%) cases and was higher in patients not receiving antiretroviral treatment or under therapeutic failure than in patients under successful highly active antiretroviral therapy (HAART) (P = 0.0076). Overall, the profile of patients with high EBV viral load included elevated HIV viremia (P = 0.0005), longer time of HIV diagnosis (P = 0.0026), and increased levels of T CD8 (+) lymphocytes (P = 0.0159). The successful amplification of the EBNA-2 gene by nested-PCR was achieved in 95 of 123 (77.2%) cases, of which 75.8% were EBV-1, 9.5% EBV-2, and 14.7% were co-infected with both EBV-1 and -2. The analysis of the BNLF-1 gene was possible in 99 of 123 (80.5%) cases, of which 50.5% had the 30-bp deletion. EBV-1 was more common than EBV-2, which may reflect the fact that the cohort was predominantly Caucasian and heterosexual.

Construction and identification of recombinant lentiviral vector containing HIV-1 Tat gene and its expression in 293T cells

Objective

To construct a lentiviral vector expressing HIV-1 Tat and identify its expression in 293T cells.

Methods

The gene fragment of HIV-1 Tat₁₀₁ was subcloned to lentiviral transfer vector pHAGE-CMV-MCS-IZsGreen, which was named pHAGE-Tat. Then the constructed pHAGE-Tat was used to co-transfect the packing 293T cells, together with the packaging plasmids pMD2.G and psPAX2. The packaged viral particles designated LV-Tat were used to infect the 293T cells and the viral titer was calculated. The expression of HIV-1 Tat in 293T cells was confirmed using RT-PCR and western blot.

Results

The recombinant lentiviral vector was successfully constructed and could express HIV-1 Tat in 293T cells. The virus titer was 5.73×10⁶ ifu/ml.

Conclusion

The successfully constructed recombinant lentiviral vector makes a strong foundation for further exploring the possible role of HIV-1 Tat in the development of prostate cancer.

Expression of EBV-encoded oncogenes and EBV-like virions in multiple canine tumors

Epstein-Barr virus (EBV) is a ubiquitous human oncovirus. Previous studies by us and others have indicated that pet dogs frequently encounter EBV or EBV-related viral infection. In this study, we explored whether EBV is involved in canine malignancies in dogs. EBV-specific BamHI W sequence was detected by polymerase chain reaction (PCR) in 10 of 12 canine tumor specimens, including 8 of 10 oral tumors. Using reverse transcription-PCR, gene expressions of latent membrane protein 1 (LMP 1) and BamHI H rightward reading frame 1 (BHRF1) were identified in 8 and 7 of 12 specimens, respectively. A novel LMP1 variant, T0905, was predominant in 5 canine tumor specimens and found to exist in EBV positive human BC-2 cells. Another LMP1 variant, T0902, was similar to human tumor variant JB7. The BHRF1 sequence identified from these canine tumors was identical to that of the B95-8 viral strain. LMP1 protein and EBV-encoded RNA (EBER) were detected by immunohistochemistry and fluorescent in situ hybridization, respectively, in several tumors, particularly in tumor nests of oral amelanotic melanomas. Furthermore, EBV-like virions adopting a herpesvirus egress pathway were detected in a canthal fibroblastic osteosarcoma and an oral amelanotic melanoma. In conclusion, we report the expressions of BHRF1 transcript (a viral anti-apoptotic protein), LMP1 (a viral oncoprotein) transcript and protein, EBER (a viral oncogenic RNA), and EBV-like virions in multiple canine tumors. The identity of BHRF1 and the resemblance of LMP1 variants between canine and human tumors indicate either a close evolutionary relationship between canine and human EBV, or the possibility of zoonotic transmission.

Gastric cancer incidence and mortality is associated with altitude in the mountainous regions of Pacific Latin America

In Latin America, gastric cancer is a leading cancer, and countries in the region have some of the highest mortality rates worldwide, including Chile, Costa Rica, and Colombia. Geographic variation in mortality rates is observed both between neighboring countries and within nations. We discuss epidemiological observations suggesting an association between altitude and gastric cancer risk in Latin America. In the Americas, the burden of gastric cancer mortality is concentrated in the mountainous areas along the Pacific rim, following the geography of the Andes sierra, from Venezuela to Chile, and the Sierra Madre and Cordillera de Centroamérica, from southern Mexico to Costa Rica. Altitude is probably a surrogate for host genetic, bacterial, dietary, and environmental factors that may cluster in the mountainous regions. For example, H. pylori strains from patients of the Andean Nariño region of Colombia display European ancestral haplotypes, whereas strains from the Pacific coast are predominantly of African origin. The observation of higher gastric cancer rates in the mountainous areas is not universal: the association is absent in Chile, where risk is more strongly associated with the age of H. pylori acquisition and socio-economic determinants. The dramatic global and regional variations in gastric cancer incidence and mortality rates offer the opportunity for scientific discovery and focused prevention programs.

Gastric cancer incidence and mortality is associated with altitude in the mountainous regions of Pacific Latin America

In Latin America, gastric cancer is a leading cancer, and countries in the region have some of the highest mortality rates worldwide, including Chile, Costa Rica, and Colombia. Geographic variation in mortality rates is observed both between neighboring countries and within nations. We discuss epidemiological observations suggesting an association between altitude and gastric cancer risk in Latin America. In the Americas, the burden of gastric cancer mortality is concentrated in the mountainous areas along the Pacific rim, following the geography of the Andes sierra, from Venezuela to Chile, and the Sierra Madre and Cordillera de Centroamérica, from southern Mexico to Costa Rica. Altitude is probably a surrogate for host genetic, bacterial, dietary, and environmental factors that may cluster in the mountainous regions. For example, H. pylori strains from patients of the Andean Nariño region of Colombia display European ancestral haplotypes, whereas strains from the Pacific coast are predominantly of African origin. The observation of higher gastric cancer rates in the mountainous areas is not universal: the association is absent in Chile, where risk is more strongly associated with the age of H. pylori acquisition and socio-economic determinants. The dramatic global and regional variations in gastric cancer incidence and mortality rates offer the opportunity for scientific discovery and focused prevention programs.