Deciphering the viral landscape in gastric cancer: comprehensive characterization and identification of the gastric cancer virome.

[UNLABELLED] Infectious diseases caused by pathogenic microorganisms and tumors arising from uncontrolled cell proliferation can be intricately linked through the lens of viromics. This study aimed to delineate the landscape of viral infections in gastric cancer, focusing on the relationship between pathogenic microorganisms and tumorigenesis. By conducting transcriptomic sequencing of gastric cancer tissues, we identified gastric cancer-associated viruses from raw transcriptomic data. This methodology was validated using public databases and experimental evidence, ensuring the authenticity of viral detection. Single-cell data further identified specific cells harboring these viruses and elucidated the correlation between viral gene expression and the genesis and progression of gastric cancer. Common tumor viruses, such as human endogenous retrovirus (HERV), Epstein-Barr virus (EBV), and human cytomegalovirus (HCMV), along with unique DNA viruses and bacteriophages, were detected in gastric cancer. Additionally, these viruses have been detected in both tumor and immune cells, indicating a close association between viral gene expression and the development of gastric cancer. This study advances the technique of screening viruses from transcriptomes, charting the distribution of viruses within tumors, clarifying the interplay between viruses and cancer, and identifying previously unknown viruses related to the occurrence and progression of cancer.

[IMPORTANCE] In our study, we have carefully examined the viral landscape in gastric cancer, supported by a series of thorough experiments that verify its reliability. Our approach has not only confirmed the presence of viruses known to be associated with cancer development but also identified a range of additional viral entities, including human cytomegalovirus (HCMV) and various herpesviruses, along with numerous bacteriophages. The high incidence of these viruses within tumor samples suggests they could be considered as potential biomarkers for early cancer detection. This method enhances our understanding of the role viruses play in cancer, which may assist scientists and medical professionals in identifying viral presence in cancers and could offer new angles for cancer prevention and the development of related measures. By identifying specific viruses linked to different cancers, we aim to improve patient outcomes.