Expression of bovine coronavirus antigens at the plasma membrane in infected cell cultures

Abstract

Infection by bovine coronavirus (BCV) may cause severe diarrhea in neonatal calves. The virus can multiply in the human adenocarcinoma cell line HRT-18 and in bovine fetal spleen cells (BFS). Fusion of BFS cells occurs after BCV infection if trypsin is added to the culture medium. This type of fusion may be induced by other enveloped viruses following the expression of virally encoded macromolecules in the plasma membrane. The presence of viral proteins in the host plasma membrane is not, however, necessary for BCV maturation since coronaviral particles are enveloped by budding into intracellular compartments. Immunogold techniques were used to determine if BCV proteins are present in the plasma membrane of the host cell and whether their absence might explain the lack of fusion in BFS cells not treated with trypsin.Monolayers of HRT-18 cells, grown in DMEM medium with 5% fetal calf serum, were infected with BCV.