The interaction of neutralized poliovirus with HeLa cells. II. Elution, penetration, uncoating.

The interaction of HeLa cells with adsorbed neutralized poliovirus was studied. In these experiments, 32P-labeled virus was allowed first to adsorb to cells and then to react with antibody, both reactions taking place at 2 degrees . The temperature was then raised to 37 degrees and the ensuing events were analyzed. The analyses were designed to measure the amounts of virus that were present as whole particles, as uncoated intact RNA, and uncoated degraded RNA. The analyses were made on the separated cell and fluid phases of each culture. In the control, in which virus had not been exposed to antibody, about 50% of the virus eluted from the cells into the fluid as a mixture of whole and degraded virus compared with about 25% for neutralized virus. In both cases almost all the eluted whole virus was not infectious and, except to a very small degree, was not reactivable by treatment with acid or sodium dodecyl sulfate, separately or together. More than 50% of the eluted material in the control was sedimentable at 100,000 g in contrast to about 10% if virus had been neutralized. An analysis of viral products, i.e., whole particles, intact RNA, degraded RNA found in association with cells or eluted from cells into the culture fluid, showed the following: (1) If combined with antibody, considerably less virus eluted as whole particles. (2) Antibody either reduced slightly or did not influence the proportion of RNA that was degraded and was contained either in the cells or in the fluid. (3) Whereas in the control appreciable amounts of intact RNA (10-15%) were found in the cells, little or none was found if virus was neutralized. (4) No intact RNA was found in the culture fluids in either case. Through the use of acid-treatment of virus-cell complexes for recovery of infectious virus, evidence was obtained indicating that neutralized virus penetrated cells at the same rate and to the same degree as unneutralized virus.