While not found in the spleen, a research group reported development of hemanigosarcomas in fat tissue of C57BL/6 mice at 4.5 months of age injected with a lung-targeted AAV6 vector encoding the envelope protein of the Jaagsiekte sheep retrovirus, suggesting that presence of this type of tumor could be related to contents of AAV [65]. Here, ERVW-1 is linked to neoplasm.