The trans Golgi network is lost from cells infected with African swine fever virus

The cellular secretory pathway is important during the assembly and envelop ment of viruses and also controls the transport of host proteins, such as c ytokines and major histocompatibility proteins, that function during the el imination of viruses by the immune system. African swine fever virus (ASFV) encodes at least 26 proteins with stretches of hydrophobic amino acids sug gesting entry into the secretory pathway (R. J. Yanez, J. M. Rodriguez, M. L. Nogal, L. Yuste, C. Enriquez, J. F. Rodriguez, and E. Vinuela, Virology 208:249-278, 1995). To predict how and where these potential membrane prote ins function, we have studied the integrity of the secretory pathway in cel ls infected with ASFV. Remarkably, ASFV caused complete loss of immunofluor escence signal for the trans Golgi network (TGN) marker protein TGN46 and d ispersed the AP1 TGN adapter complex. Loss of TGN46 signal was not due to d egradation of TGN46, suggesting redistribution of TGN46 to other membrane c ompartments. ASFV markedly slowed transport of cathepsin D to lysosomes, de monstrating that loss of TGN structure correlated with loss of TGN function . ASFV shows a tropism for macrophages, and it Is possible that ASFV compro mises TGN function to augment the activity of viral membrane proteins or to suppress the function of host immunoregulatory proteins.