Entry of poliovirus into cells is blocked by valinomycin and concanamycin A.
Poliovirus contains a virus particle devoid of a lipid envelope that does not require an intact pH to enter into susceptible cells. Thus, the blockade of pH gradient generated in endosomes is not sufficient to impede the translocation of poliovirus particles to the cytoplasm, suggesting that translocation takes place at the plasma membrane. Measuring both viral protein synthesis and eIF4G-1 cleavage mediated by poliovirus protease 2A has been used to monitor productive entry of poliovirus into cells. Translation of the input poliovirus RNA produces enough 2A(pro) to cleave eIF4G-1, providing a sensitive assay to estimate poliovirus RNA delivery to the cytoplasm followed by its translation. Combination of concanamycin A, a vacuolar proton-ATPase inhibitor, and valinomycin, an ionophore that promotes K(+) efflux from cells, powerfully prevented poliovirus infection. Moreover, modifying the ionic conditions of the culture medium (increasing the concentration of K(+) and decreasing the concentration of Na(+)), together with concanamycin A, also significantly interfered with poliovirus entry. These findings suggest that poliovirus RNA requires an intact concentration of K(+) ions inside the cells to be uncoated and to gain access to the cytoplasm. In addition, the actual contribution of concanamycin A (as well as other inhibitors of endocytosis) to the total inhibition of productive poliovirus entry points to the idea that at least some percentage of polioviral subparticles translocates from the endosomes.
Irurzun
A
A
Centro de Biología Molecular, UAM-CSIC, Universidad Autónoma de Madrid, Canto Blanco, 28049 Madrid, Spain. airurzun@cbm.uam.es
Carrasco
L
L
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology*; D002414:Cations, Monovalent / Q000378:metabolism; D002461:Cell Line, Transformed; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D039603:Eukaryotic Initiation Factor-4G; D006367:HeLa Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology / Q000821:virology*; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism / Q000821:virology; D018942:Macrolides; D008564:Membrane Potentials / Q000187:drug effects; D010446:Peptide Fragments / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000378:metabolism; D017955:Poliovirus / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D025262:Vacuolar Proton-Translocating ATPases; D014634:Valinomycin / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects
D000900:Anti-Bacterial Agents; D000998:Antiviral Agents; D002414:Cations, Monovalent; D002966:Clathrin; C113920:EIF4G1 protein, human; D004791:Enzyme Inhibitors; D039603:Eukaryotic Initiation Factor-4G; D018942:Macrolides; D010446:Peptide Fragments; D010448:Peptide Initiation Factors; D014634:Valinomycin; C036978:concanamycin A; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D011188:Potassium