The E3 protein of bovine coronavirus is a receptor-destroying enzyme with acetylesterase activity

Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029-6574.
Journal of Virology (Impact Factor: 4.44). 01/1989; 62(12):4686-90.
Source: PubMed


In addition to members of the Orthomyxoviridae and Paramyxoviridae, several coronaviruses have been shown to possess receptor-destroying activities. Purified bovine coronavirus (BCV) preparations have an esterase activity which inactivates O-acetylsialic acid-containing receptors on erythrocytes. Diisopropyl fluorophosphate (DFP) completely inhibits this receptor-destroying activity of BCV, suggesting that the viral enzyme is a serine esterase. Treatment of purified BCV with [3H]DFP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins revealed that the E3 protein was specifically phosphorylated. This finding suggests that the esterase/receptor-destroying activity of BCV is associated with the E3 protein. Furthermore, treatment of BCV with DFP dramatically reduced its infectivity in a plaque assay. It is assumed that the esterase activity of BCV is required in an early step of virus replication, possibly during virus entry or uncoating.

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Available from: Reinhard Vlasak
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    • "Some coronaviruses like bovine coronavirus (BCoV) resemble influenza C virus by using N-acetyl-9-O-acetyl neuraminic acid (Neu5,9Ac2) as a receptor determinant on cell surface macromolecules for binding to and infection of target cells [28], [29]. Furthermore, they contain an acetylesterase activity that releases the 9-O-acetyl group from Neu5,9Ac2 and thus is able to inactivate the receptor determinant [30]. This so-called receptor-destroying enzyme may – in analogy to influenza viruses – help to avoid binding events that do not result in infection, e.g. "
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    • "Several lines of evidence support an important role of the HE protein in BCV infectivity: (i) The HE protein of BCV was shown to induce mAbs that neutralized virus infectivity in vitro (in cell cultures) and in vivo (in animals); four neutralizing epitopes were identified on the HE protein of BCV (Deregt and Babiuk, 1987; Deregt et al., 1989). (ii) Treatment of BCV with inhibitors that specifically inactivate acetylesterase reduced viral infectivity by 3 logs or greater, while the same treatment of influenza A virus did not affect virus infectivity, indicating that acetylesterase activity is required for BCV infectivity (Vlasak et al., 1988). (iii) Both the S and HE proteins of BCV recognized the same receptor-determinant of the cultured cells and erythrocyte (Schultze et al., 1991; Schultze and Herrler, 1992, 1994). "
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    • "(Risco et al., 1996). A fifth component in the envelope of some MHV strains is the 65 kDa HE protein with homologies to haemagglutinin–esterase protein of influenza C virus (Vlasak et al., 1988). It presumably serves a similar role to the influenza viral protein HN in the destruction of the viral receptor following virus entry and release. "
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