Abortive infection of influenza virus in Ehrlich ascites tumor cells. Unusual fragility of virus particles.

Noninfectious virus particles were produced in Ehrlich ascites tumor cells infected intraperitoneally with fowl plague virus. The PFU yield of virus per cell was less than 0.1 and the ratio PFU/HA units in the progeny virus was less than 10(3). The virus particles had the same morphology and size as egg-grown virus but were more fragile. They were disrupted by centrifugation through sucrose and caesium chloride gradients, but this disruption was avoided by fixing the particles with formaldehyde before centrifugation. Analysis of polypeptides by SDS-PAGE showed that ascites-grown virus particles contained reduced amounts of matrix protein compared with egg-grown virus.