Sensitivity of the transmissible green turtle fibropapillomatosis agent to chloroform and ultracentrifugation conditions

Transmission experiments were conducted to further characterize the filterable transmissible agent that causes GTFP, fibropapillomatosis of green turtles Chelonia mydas. Cell-free homogenates (unfiltered or 0.45 mu m filtered), prepared from fibropapillomas of free-ranging green turtles (donors) and inoculated into 18 captive-reared recipients, induced tumors in recipients with an overall success rate of 83.3% (range: 0 to 100%). Chloroform treatment prior to inoculation destroyed tumorigenic activity of these homogenates. These data are consistent with the hypothesis that the GTFP agent contains a lipid component, such as a viral envelope, necessary for tumorigenicity. Ultracentrifugation of tumor homogenates for 2 h at 100 000 x g cleared the supernatant of tumorigenic activity. Tumorigenicity was recovered in the ultracentrifuge pellet. The pellet, however,was less effective at inducing tumors than the starting material, indicating that the GTFP agent was damaged by these ultracentrifugation conditions. The possibility that the GTFP-associated herpes virus is the etiologic agent of GTFP was further supported by the observation of eosinophilic intranuclear inclusions in 24.3% of experimentally induced tumors in this study. Tumorigenic activity survived storage for several months at -80 degrees C and at least 1 yr at -180 degrees C, making it feasible to isolate the GTFP agent and its genome from frozen archived material once methods have been optimized.