piRNA-mediated silencing of exogenous retrovirus in mouse spermatogonial stem cells.
Viral integration into germline cells poses a transgenerational threat to genome stability, yet protective mechanisms remain unclear. We demonstrate that Trp53 and PIWI-interacting RNAs (piRNAs) are essential for antiviral defense through regulation of the cancer-testis antigen MAGEA5. Transient viral infection in sper...