Identification of heat-dissociable RNA complexes in two porcine coronaviruses

THE coronavirus genome has been shown to comprise single-stranded RNA(1,2). Examination of the viral nucleic acid synthesised by pig kidney cells infected with transmissible gastroenteritis virus (TGEV) suggested that several molecular species, ranging in size between 18 and 28S, were involved in the viral replicative cycle(3); similarly Tannock found a wide variation in the size of RNA molecules extracted from avian infectious bronchitis virus (IBV) by a phenol–sodium dodecyl sulphate (SDS) method(2). Extraction of IBV RNA by 1% SDS at 60 °C has, however, revealed a single component of molecular weight 9×10(6) corresponding to 60S by electrophoresis through 2.2% polyacrylamide gels(4).