Anelloviruses and Cancer.

Anelloviruses are among the most prevalent viruses within the human virome, detected in >90% of healthy individuals. Despite their ubiquity, the role of anelloviruses in human health remains elusive. This review examines the potential associations of the anelloviruses torque teno virus (TTV), torque teno midi virus (TTMDV), and torque teno mini virus (TTMV) with various cancers, highlighting the mixed conclusions from current epidemiological studies. Anelloviruses may modulate cancer development through abnormal gene fusion, immune response, and Toll-like receptor 9 (TLR9) activation. On the other hand, anelloviruses might suppress tumor formation through TTV-derived apoptosis-inducing protein (TAIP) and NF-κB signaling inhibition. The high prevalence of anelloviruses in cancer patients could also be attributed to their immunocompromised status rather than a direct causative role of the viruses. This review underscores the need for more comprehensive studies, including in vitro and in vivo experiments, to clarify the role of anelloviruses in cancer development and progression.