A continuous bovine kidney cell line for routine assays of foot-and-mouth disease virus

A continuous bovine kidney cell line, LF-BK, arose from primary bovine calf kidney cells that survived infection with a temperature-sensitive mutant of foot-and-mouth disease virus. No virus was recovered after the first passage. Cells of Passage 48 were inoculated into two steers which remained healthy and did not develop neutralizing antibodies to the virus. The karyotype of cells of the 53rd and 87th passages was similar and revealed that the cells were markedly transformed. The modal number of diploid chromosomes was 52 at both passage levels. LF-BK cells and primary bovine kidney cells were equally susceptible in plaque assays to each of the 7 types of foot-and-mouth disease virus. The cell line and primary bovine kidney cells were less susceptible than primary bovine thyroid cells to several subtypes of the virus in suspensions of tongue epithelium. The LF-BK continuous cell line is recommended for routine plaque assays or plaque neutralization tests as a substitute for primary bovine kidney cells.