The P2 and P3 Regions of the Poliovirus Genome are Preferentially Translated at Alkaline pH in Infected HeLa Cells

Abstract

SUMMARYHeLa cells infected with poliovirus exclusively synthesized proteins coded by the P2 and P3 regions of the viral genome when they were placed in an alkaline medium lacking sodium ions. The amount of viral protein synthesized was augmented by increasing the concentration of KC1. Also in the presence of KC1, the ceils continued synthesizing this altered pattern of proteins for longer times. This effect occurred in the presence of guanidine, it was reversible, and the normal pattern of poliovirus proteins reappeared when control medium was added, even when guanidine was present. These findings suggest that truncated viral RNA is not made under these conditions. Pactamycin and sodium fluoride, two known inhibitors of the initiation of translation, blocked protein synthesis in cells placed in alkaline medium, indicating the possibility that initiation at internal sites of the viral mRNA may take place under these conditions. Finally, the proteins synthesized were analysed by two-dimensional gel electrophoresis. The proteins migrated as authentic viral proteins indicating that if internal initiation takes place, at least some of these initiation events occur in phase with the initiation codon present in the poliovirus genome.

Human immunodeficiency virus infection of T-lymphoblastoid cells reduces intracellular pH

“…Reduction in pH i potentially could be important in several aspects of the HIV-1 replication cycle. In other viral systems, changes in pH of various cellular compartments trigger conformational changes in virion proteins during uncoating and/or penetration, permit effective virion assembly, budding and maturation, or alter expression or processing of viral proteins (5,7,10,31,33,41,43). The M 2 protein of influenza virus and the E2 protein of Semliki Forest virus are both thought to form functional ion channels that can transport protons and other ions (43,47).…”