Electron Microscopic Study of Rhinovirus Replication in Human Fetal Lung Cells

Abstract

Human cmbryo lung cells infected with rhinovirus type 2 (HGP strain) were sampled at intervals during viral growth and thin sections examined by electron microscopy. Infectivity assay showed an increase of intracellular virus 7 to 8 hr postinoculation and a peak titer at 16 to 18 hr. Changes resulting from infection, as revealed by electron microscopy, comprised (i) the appearance in the cytoplasm, at 8 hr postinfection, of large ribosomal clusters, membrane-enclosed bodies which proliferated extensively in the central zone of the cell, and viroplasm, aggregates of irregularly dense, coarse, granular material, and (ii) the appearance in the cytoplasm, at 16 hr postinoculation, of recognizable progeny virus particles. The particles were aligned along parallel fibrils or were found singly in some instances. As incubation continued, the particles became increasingly more spherical, and formed parallel long rows, and (iii) eventually, 24 hr after inoculation, formed closely packed viral crystals of a rectangular or hexagonal lattice. The mature progeny particles were 26 to 28mμ diameter. These changes were reminiscent of those reported previously for the polio and other enteroviruses.