RELATIONSHIP OF DONOR AGE TO IN VITRO PRODUCTION OF FOOT-AND-MOUTH DISEASE VIRUS BY MOUSE KIDNEY CELLS.

Multiplication of foot-and-mouth disease virus (FMDV) was compared in kidney cells from 7- to 35-day-old mice representing various degrees of age resistance to this virus. Three types of cell preparations were used: primary monolayer cultures, suspensions of dispersed cells, and suspensions of minced tissue. Virus multiplication in the two types of cell suspensions was related to the age of the donors both in regard to time when multiplication first became evident and to the amount of virus produced. While adsorption rates were similar in the cells from all age groups, virus multiplication began earlier in cells from younger mice and more virus was produced by these cells than by cells from older animals. There was no significant difference in the virus growth rates in the primary monolayer cultures of cells. The results indicate that kidney cells from mice 7 to 35 days old vary in their ability to produce virus in relation to the degree of susceptibility of the cell donors. After propagation of the cells in primary monolayer cultures, however, this difference no longer exists probably because of cell selection under the cultural conditions.