The Coronavirus Nonstructural Proteins

Abstract

The definition of a group of virus-coded proteins/polypeptides, the nonstructural, as those not found in virions is crude, but has some merit in that it immediately focuses attention on the potential difficulties encountered in defining them. It leaves aside the practical difficulties implicit in attempting to detect small amounts of virus-coded polypeptides, particularly if they are of low molecular weight, which may be present in virions, and, on the other hand, in deciding whether or not such polypeptides, if detected, are present adventitiously. This chapter will thus consider currently available information relating to Coronavirus polypeptides (or predicted polypeptides) other than those routinely present in the virions of all coronaviruses subjected to detailed analysis, i.e., the spike glycoprotein (S), the integral membrane glycoprotein (M), the small-membrane protein (sM), and the nucleocapsid protein (N), or present in only some coronaviruses, i.e., the hemagglutinin esterase (HE) glycoprotein.