Avian viruses in adult cells in vitro A comparison of fowlpox, bronchitis, laryngotracheitis, and newcastle disease viruses in tissue cultures of embryonic and adult fowl cells

Abstract

Tissue culture techniques have been used to compare the susceptibility of normal adult fowl fibroblasts and epithelial cells and embryonic fowl fibroblasts to three strains of Newcastle disease virus (NDV) (one virulent, two avirulent), fowlpox (FP) virus, infectious bronchitis (IB) virus, and infectious laryngotracheitis (ILT) virus. All strains of virus studied were able to multiply in adult epithelial cells; only IB and ILT viruses were not shown to multiply in adult fibroblasts. Embryonic fibroblasts supported the multiplication of all the viruses except IB, which could be recovered only from the first passage in vitro. A characteristic cytopathic effect (CPE) was seen in adult epithelial cells infected with each of the virus types studied (except IB virus). In the case of NDV this consisted in the formation of inclusion bodies in the cytoplasm and syncytia; with FP virus, rounding of cells, cytoplasmic eosinophilia, and development of protrusions on the cell were observed; and with ILT virus nuclear inclusion bodies were formed, with or without concomitant syncytia. In adult and embryonic fibroblasts similar cytopathic effects were observed, but they were not always so extensive. In infected organ cultures of embryonic fowl trachea the effects of virus action on the tissues resembled those seen in infected chorioallantoic membranes or in infected fowls in vivo. The effects on individual cells were of a similar kind to those found in monolayer cultures.