A recombinant transmissible gastroenteritis coronavirus (rTGEV) in which E gene was deleted (rTGEV-Ξ”E) has been engineered. This deletion mutant only grows in cells expressing E protein (E+ cells) indicating that E was an essential gene for TGEV replication. Electron microscopy studies of rTGEV-Ξ”E infected BHK-pAPN-E- cells showed that only immature intracellular virions were assembled. These virions were non-infectious and not secreted to the extracellular medium in BHK-pAPN-E- cells. RNA and protein composition analysis by RNase-gold and immunoelectron microscopy showed that rTGEV-Ξ”E virions contained RNA and also all the structural TGEV proteins, except the deleted E protein. Nevertheless, full virion maturation was blocked. Studies of the rTGEV-Ξ”E subcellular localization by confocal and immunoelectron microscopy in infected E- cells showed that in the absence of E protein virus trafficking was arrested in the intermediate compartment. Therefore, the absence of E protein in TGEV resulted in two actions, a blockade of virus trafficking in the membranes of the secretory pathway, and prevention of full virus maturation. Β© 2007 Elsevier Inc.