In vitro measurement of the potency of inactivated foot-and-mouth disease virus vaccines

Abstract

Inactivated vaccines have been prepared from one strain of FMD virus grown in guinea-pig pad epithelium, unweaned mice and cultured pig kidney and baby hamster kidney cells. The potencies of these vaccines in protecting guinea-pigs against challenge with inoculated infective virus of the same strain have been compared and related to the amounts of 25 mμ component present in the different virus suspensions. Although it was possible to obtain a relationship between the content of 25 mμ component and potency for an individual source of virus, this relationship does not hold for all the different sources of virus used. It is suggested that the reason for this failure is the partial masking of the 25 mμ component by a cell constituent present in some of the virus suspensions so that the component is incompletely estimated by the complement-fixation test.