Observations on the membrane organization of standard and incomplete influenza grown in MDBK cells.

The phospholipid content and composition of incomplete WSN influenza virions grown in MDBK cells were compared with standard particles grown at low multiplicity of infection and found to be indistinguishable. The ESR spectra of incomplete and standard virions labeled with a stearic acid spin label were also indistinguishable, indicating that the rigidity of the viral bilayer was not measurably different in the two kinds of particles. Evidence is presented that a small peptide or peptides of the viral glycoproteins remains associated with the particle after proteolytic digestion of the glycoprotein spikes. Since the membranes of incomplete viral particles have previously been shown to contain approximately twice the amount of glycoproteins present in standard virus, it is concluded that these small peptides exert no measurable effect on bilayer composition or rigidity.