Stabilization of "A" particles of coxsackievirus B3 by a HeLa cell plasma membrane extract

Previous studies in our laboratory showed that HeLa cell plasma membranes were recovered from sucrose gradients in two major bands and that the heavier band possessed a putative inhibitor of uncoating of coxsackievirus B3. It has now been found that the mechanism of inhibition is the stabilization of "A" particles against inactivation at 37 degrees C. [3H]uridine-labeled virions converted to A particles by band 4, the heavier band, were four times more stable at 37 degrees C than those produced by band 3. Partially purified A particles from both bands were equally unstable. It was found that the stabilizing factor was extractable by saline from band 4 and remained soluble after centrifugation (109,000 X g for 2 h). Addition to A particles of this soluble factor isolated from either band 4 or band 3 stabilized the A particles. The stabilizing factor could not be replaced by an extract from band 3 or by bovine serum albumin. Thus, the finding that the membrane factor inhibits virus uncoating by stabilizing A particles against spontaneous disruption at 37 degrees C focuses attention on an inherent problem associated with defining receptor-mediated virus uncoating.