Removal of foot-and-mouth disease virus infectivity in salted natural casings by minor adaptation of standardized industrial procedures

Intestines are used for the production of natural casings as edible sausage containers. Derived from animals (pigs and sheep) experimentally infected with FMDV (initial dosage 107.3 PFU/ml, strain O1Kaufbeuren), these natural casings were treated with sodium chloride or a phosphate salts/sodium chloride mixture and the residual FMDV titres measured. After storage at about 20 °C, no remaining infectivity was found after either treatment, whereas casings stored at 4 °C still contained infectivity. Storage of salted casings at about 20 °C for 30 days is already part of the Standard Operating Procedures (included in HACCP) of the international casing industry and can therefore be considered as a protective measure for the international trade in natural casings.