Heterogeneity of infectious bronchitis virus grown in eggs

Abstract

Egg-grown infectious bronchitis virus, strain Beaudette, was concentrated and centrifuged on sucrose density gradients to separate the virus into five peaks with densities of 1.144, 1.160, 1.172, 1.191 and 1.218 g/cm3. All peaks retained infectivity, complement fixation activity and were labelled with 3H-uridine. Morphologically the densest peak consisted of very large virus particles and amorphous material, the other peaks consisted of mainly intact particles although small differences in size and pleomorphism were seen. Polyacrylamide gel electrophoresis of material from the density gradient peaks revealed four major polypeptides and at least 10 minor polypeptides. The proportions of the polypeptides were approximately similar for all peaks with the exception of the densest peak in which the major polypeptides were greatly reduced. The four major polypeptides had approximate molecular weights of 1. 52,000, 2. 45,000, 3. 34,000, 4. 32,000. The major polypeptides 1 and 4 were shown to be glycosylated as were two of the minor polypeptides.

Structural Proteins and Glycoproteins of Infectious Bronchitis Virus Particles Labeled during Growth in Chick Embryo Cells

“…Rate zonal sedimen tation (120,000 g for 90 min in a 20-60% w/v sucrose gradient) of concentrated virus from infected allantoic fluid gave three separate peaks of infectivity ; the major peak, containing 80% of the infectivity, sedimented fastest (re sults not shown). Similar heterogeneity of IBV particles has been reported previously [11].…”

“…molecular weights 90,000-100,000 and 150,000 to 185,000, enclosing a nucleoprotein of about molecular weight 50,000; this appears to be associated with a small glycoprotein of molec ular weight 18,000-30,000 [2][3][4][5][6][7][8][9][10], In contrast, the reports on the structural polypeptides of the avian infectious bronchitis virus (IBV) vary considerably [11][12][13][14][15][16][17][18]. The number of polypep tides identified ranges from 4 to 30 and, except for a major polypeptide of molecular weight approximately 50,000, the sizes, relative abun dances and glycosylation of peptides differ considerably among these studies.…”

Ribonucleoprotein of Avian Infectious Bronchitis Virus

“…wt. about 50000 has been found in all cases (Bingham, 1975;Collins et al, 1976;Alexander & Collins, 1977;Macnaughton & Madge, 1977a;Macnaughton et aL, 1977;Nagy & Lomniczi, 1979;Lanser & Howard, 1980), and this is associated with the RNA genome (Macnaughton et al, 1977). Our RNP preparations from sucrose gradients contained such a polypeptide, identical in tool.…”

Structural Polypeptides of Coronavirus IBV

“…glycopeptide of MHV-A59 is largely embedded within the virus membrane (M), and protrudes at both the outer (Sturman, 1977;Sturman & Holmes, 1977;Wege et at., 1979) and inner (Sturman et aL, 1980) (Collins & Alexander, 1980 a). Many of these are presumably host-coded polypeptides, but no attempt has been made to differentiate virus-and host-coded components, principally because most studies of IBV polypeptides have been made using non-labelled virus grown in embryonated chicken eggs (Bingham, 1975;Collins et aL, 1976;Alexander & Collins, 1977;Nagy & Lomniczi, 1979;Collins & Alexander, 1980a) although Lanser & Howard (1980) have iodinated IBV after purification. To investigate this problem, and to produce IBV rapidly and economically, I have radiolabeUed the polypeptides of IBV during multiplication in de-embryonated chicken eggs.…”