Viruses in cancers among the immunosuppressed

Area of Science:

• Virology
• Oncology
• Immunology
• Transplantation Medicine

Background:

• Immunosuppressed individuals, particularly solid organ transplant recipients, exhibit increased incidence of various cancers.
• While some cancers are known to be virus-associated, others, like nonmelanoma skin carcinoma (NMSC), have unclear viral links.
• Understanding the virome in cancer development among the immunosuppressed is crucial for risk assessment and prevention.

Purpose of the Study:

• To investigate the presence and types of viruses in cancer specimens from immunosuppressed solid organ transplant patients.
• To identify novel viral sequences and characterize their prevalence in different cancer types, especially NMSC.
• To explore the potential role of viruses in cancers occurring in immunocompromised hosts.

Main Methods:

• A cohort study followed 13,429 solid organ transplant patients in Sweden for cancer occurrence.
• Tumor specimens (62 NMSCs, 27 other cancers) were sequenced using bioinformatics algorithms (paracel-blast and HMM).
• Sequence analysis focused on detecting known and novel viral families and contigs.

Main Results:

• Mimiviridae and Papillomaviridae were frequently detected in NMSC specimens.
• Hidden Markov Model (HMM) analysis revealed numerous previously undescribed viral contigs, with Mimiviridae-related sequences being most common.
• HMM identified viral sequences in all 27 non-NMSC cancer specimens, with a novel Mimivirus sequence (SE996) being highly prevalent.

Conclusions:

• A wide range of viruses are detectable in cancers affecting immunosuppressed individuals.
• Sequences related to the Mimiviridae family were the most prevalent across different cancer types.
• Further investigation is required to determine the biological significance and etiological role of these detected viruses in cancer development.