Malignant lymphoma in cottontop marmosets after inoculation with Epstein-Barr virus

Neoplasia resembling human malignant lymphoma, reticulum cell sarcoma type, occurred in cottontop marmosets inoculated with materials containing Epstein-Barr virus. One of four monkeys that received autologous cells transformed in vitro by Epstein-Barr virus developed lymphoma in mesenteric lymph nodes 7.5 months after inoculation. Three of four marmosets inoculated with cell-free Epstein-Barr virus developed lymphoma. The latent period for detectable tumor formation after addition of virus was 31-46 days. Immunosuppressive drugs given with the virus accelerated the course of disease. Nevertheless, malignant lymphoma occurred in an animal given only cell-free virus. Six of eight marmosets inoculated with the virus demonstrated antibodies to the virus. Four marmosets not exposed to the virus, including two that received immunosuppressive drugs, developed neither tumors nor antibodies to Epstein-Barr virus. Virus antigen detectable by immunofluorescence was found in 5% of cells shed from one tumor maintained in organ culture. These results imply that Epstein-Barr virus is capable of inducing malignant lymphoma in at least one primate species. Additional evidence is required before its oncogenic capacity in this host can be accepted without reservation.