A planarian nidovirus expands the limits of RNA genome size

Amir Saberi; Anastasia A. Gulyaeva; John L. Brubacher; Phillip A. Newmark; Alexander E. Gorbalenya

We then analyzed planarians by electron microscopy (EM) for the presence of viral structures. Membrane-bound compartments with 90-150 nm spherical-to-oblong particles resembling nidoviral nucleocapsids (43, 44) were found in the cytoplasm of mucus-secreting cells, which are abundant in planarian parenchyma. These sub-epidermal gland cells are notable for their extensive rough endoplasmic reticulum and long projections into the ventral epithelium, through which they secrete mucus (Fig. S18) . These cells provide an ideal environment for nidoviral replicationwhich co-opts host membranes to produce viral replication complexes (45) . Putative viral particles were found both in deep regions of these cells, and in their trans-epidermal projections (Fig. 3A-C) . The latter location suggests a author/funder. All rights reserved. No reuse allowed without permission.