Subcellular distribution of the foot-and-mouth disease virus 3A protein incells infected with viruses encoding wild-type and bovine-attenuated formsof 3A

Picornavirus infection induces the proliferation and rearrangement of intra cellular membranes in response to the synthesis of nonstructural proteins, including 3A. We have previously shown that changes in 3A are associated wi th the inability of a Taiwanese strain of foot-and-mouth disease virus (FMD V) (OTai) to grow in bovine cells and cause disease in cattle, although the virus grows to high titers in porcine cells and is highly virulent in pigs (C. W. Beard and P. W. Mason, 2000, J. Virol. 74, 987-991). To study if di fferences in the distribution of 3A could account for the species specifici ty of OTai, we compared the localization of the OTai 3A with a bovine-virul ent 3A (serotype A12) in keratinocytes prepared from the tongues of cattle and pigs. Following either infection of keratinocytes or transfection with 3A we were unable to discern differences in 3A distribution in either speci es of keratinocyte, independent of the strain of virus (or 3A) utilized. In both cell types, 3A distributed in a pattern that overlapped with an endop lasmic reticulum (ER) marker protein, calreticulin (CRT). Furthermore, alth ough FMDV infection or transfection with 3A did not result in a gross redis tribution of CRT, both virus infection and 3A transfection disrupted the Go lgi. Other picornaviruses that disrupt Golgi function are sensitive to bref eldin A (BFA), a fungal metabolite that interferes with retrograde transpor t between the Golgi and the ER. Interestingly, BFA has little effect on FMD V replication, suggesting that FMDV may acquire cellular membranes into its replication complexes in a manner different from that of other picornaviru ses.