Vaccination With Feline Leukemia Cells 1.2.3

ABSTRACT-Young cats (3-6 mo old) were challenged with oncogenic Snyder-Theilen feline sarcoma virus (FeSV) after vaccination with live or killed FL74 cat lymphoma cells. Com-pared with controls immunized with normal cat fibroblasts. the FL74-vaccinated cats exhibited increased resistance to FeSV-induced progressive primary and disseminated secondary tumors. Maximum protection was achieved by vaccination with live FL74 cells or with a low dose of freeze-thawed cells. but tumor cells inactivated by glutaraldehyde or paraformaldehyde were also effective. Infectious helper feline leukemia virus (FeLV) was detected in the blood of all cats after FeSV challenge. but the duration and magnitude of this viremia were reduced in animals that had been previously vaccinated with live. freeze-thawed. or paraformaldehyde-fixed cells. Although immunized cats were resistant to FeSV-induced tumors and FeLV viremia. no evidenc