LAMINATED CISTERNAE OF THE ROUGH ENDOPLASMIC-RETICULUM INDUCED BY CORONAVIRUS MHV-A59 INFECTION

  • 1 January 1985
    • journal article
    • research article
    • Vol. 36  (1) , 108-115
Abstract
The infection of murine fibroblasts of the sac- line with a coronavirus, mouse hepatitis virus strain A59 (MHV-A59), results in a novel modification to some cisternae of the rough endoplasmic reticulum(RER). From 8 h post infection (h.p.i.) pairs of cisternae closely, stably and uniformly aligned were seen in thin sections. Serial sectioning shows that the regions of pairingor lamination extend for many thousands of nm in 2 dimensions, with the spacing between the juxtaposed membranes remaining very uniform at .apprx. 18 nm. These structures appear coincident with the onset of accumulation of the viral glycoprotein E1 in the RER membrane but 2 h after the viral glycoprotein E2 can first be detected there. Ribosomes are excluded from the paired cisternal surfaces, while budding of progeny virions has never beenseen at the cisternal membranes facing the cytosol, although ribosomes bind there. The lumina of paired cisternae are usually devoid of virions which accumulate in areas where the paired cisternae diverge. Electron immunocytochemistry shows that both E1 and E2 glycoproteins are abundant in the paired cisternae. following labeling for the E1 glycoprotein we see a periodic fine structure, rows of beads with a center to center spacing of .apprx. 7.5 nm, in the region between the paired membranes. In oblique sections of this region in cells fixed as if for the immunoperoxidase labeling, but omitting all its steps we see parallel rows of beads separated by .apprx. 7 nm. Evidently, the membrane spanning viral glycoprotein E1 together with viral nucleocapsids may be involved in laminating cisternae of the RER.