In vitro detection of Shiga toxin using porcine alveolar macrophages

Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, VPDL Research Unit, USDA, Agricultural Research Service, Ames, IA, USA.

Porcine alveolar macrophages were found to be highly susceptible to the cytolytic effects of a toxin (Shiga toxin [Stx]) produced by certain strains of Escherichia coli and sometimes associated with clinical disease in pigs and other animals. In comparison with the cells that are most commonly used for Stx detection and titration in vitro (namely, Vero cells), porcine alveolar macrophages appeared to be generally more sensitive and test results could be obtained in less time. Moreover, unlike Vero cells, porcine alveolar macrophages need not be continuously propagated to ensure immediate availability. They can simply be removed from a low-temperature repository, thawed, seeded, and shortly thereafter exposed to the sample in question. These characteristics suggest that porcine alveolar macrophages may be useful in developing a highly sensitive and timely diagnostic test for Stx.