Adenovirus cellular receptor site recirculation of HeLa cells upon receptor-mediated endocytosis is not low pH-dependent.

HeLa cells were depleted of 75% of the available adenovirus type 2 specific cellular receptor sites (CRSs) by controlled attachment of viruses at a high multiplicity of infection. Upon removal of unattached viruses and further incubation, the cells were able to recycle the CRSs to 75% of the level of uninfected control cells within 5 h. The rate of virus receptor recycling was approx. 1 CRS x min-1 x cell-1. The existence of receptor recycling further strengthens the involvement of a total process of receptor-mediated endocytosis in adenovirus internalization. The recirculation process was neither affected by the lysosomotropic agents ammonium chloride and amantadine-HCl, nor by the ionophore monensin or the multifunctional weak-base amine chloroquine.