Abstract

Ultraviolet (UV) and thermal methods of inactivating the oncogenic potential of C-type particle-producing feline oncornavirus-induced tumor cells were developed. The techniques were evaluated by several parameters for their use in preparation of cellular immunogens. The UV inactivation dose required to reduce the number of focus-forming units per ml by 1 log 10 for FL-74 lymphoblastoid cell-associated feline leukemia virus was 44,000 ergs/sq mm, and the thermal inactivation dose required to reduce the number of focus-forming units per ml by 1 log 10 at 45° was 16 min. Inactivation of greater than 6 log 10 of virus per ml associated with 4 x 10 8 cells required a UV dose of 270,000 ergs/sq mm, 100 min at 45° or 3 min at 56°. All three treatments concomitantly destroyed the replicating potential of FL-74 cells as shown by their inability to propagate under normal growth conditions and to incorporate 3 Hthymidine into nuclear DNA. UV inactivation and thermal inactivation at 45° allowed the best retention of feline oncornavirus-associated cell membrane antigen. A 50% loss in antigenic activity was observed as a result of 56° treatment, but this method was the only one that did not destroy the surface structural integrity of FL-74 cells. 1 This study was conducted under Contract NO1 CP 5-3571 within the Virus Cancer Program of the National Cancer Institute, NIH, USPHS.