Survival of Foot-and-Mouth Disease Virus in Casein and Sodium Caseinate Produced from the Milk of Infected Cows1

Abstract

Milk-borne transmission of foot-and-mouth disease virus (FMDV) was implied during the 1967–1968 epizootic in England. Consequently, experiments were designed to study survival of FMDV in milk and dairy products. As part of these studies, eight batches of casein were prepared from milk collected at various times after infection of cows with FMDV. Raw skimmilk was used in two batches and pasteurized (72 C, 15 sec), skimmilk was used in six. Casein was obtained by acidulation of skimmilk to pH 4.6 with HCI. Each batch was tested for FMDV infectivity either as casein or sodium caseinate in cell cultures and by inoculation of cattle. Samples assayed in cell cultures did not show evidence of infectious FMDV. However, cattle inoculated with these samples became infected with FMDV in one of two trials in which the casein was prepared from raw skimmilk and in three of six trials with skimmilk which was pasteurized. Samples from one of two dried casein batches infected test cattle. Samples from four of six batches of casein prepared from uninfected cows milk to which FMDV was added before pasteurization also infected cattle.