A Poliovirus-induced Cytoplasmic Membrane Complex is Exploited by the RNA Polymerase of Superinfecting Mouse Elberfeld (ME) Virus

Abstract

SUMMARYThe preexistence of a cytoplasmic membrane complex in HEp-2 cells, induced by poliovirus when inhibited in its reproduction by guanidine, was a prerequisite for accelerated reproduction of superinfec, ting Mouse Elberfeld (ME) virus. Guanidineinhibited poliovirus induced a membrane complex of 470S that was successively modified into a faster sedimenting membrane complex (up to 700S) by superinfecting ME virus and exploited for ME virus reproduction. The modified membrane complex was the site for ME virus-specific RNA polymerization characterized by the existence of in vivo and in vitro activity of ME virus RNA polymerase associated with the modified membrane complex. Proof of membrane-bound RNA polymerase and newly synthesized ME virus RNA including replicative intermediate led to the conclusion that superinfecting ME virus exploits the 'poliovirus/guanidine'-induced complex as the site of action of its replication complex.Mixed infections with the two picornaviruses, poliovirus and Mouse Elberfeld (ME) virus, revealed that virus-specific membrane alterations of the infected cells may occur independently of virus reproduction. (i) In cells simultaneously infected with both viruses, ME virus reproduction is inhibited by interfering poliovirus. Under these conditions non-reproducing ME virus determines the membrane changes at the cell surface (Zeichhardt et al., 1982). (ii) In a mixed infection in the presence of guanidine, poliovirus reproduction is inhibited (Baltimore et al., 1963); however, reproduction of ME virus is advanced (Diefenthal et al., 1973;Zeichhardt et al., 1981). The reproduction of ME virus is accelerated by 1 h in a simultaneous mixed infection and by as much as 3 h when the cells are preinfected with poliovirus for at least 2 h. Under these conditions poliovirus is not rescued by superinfecting ME virus, i.e. complementation does not take place between ME and poliovirus reproduction. As we were able to show recently (Zeichhardt et al., 1981), poliovirus inhibited by guanidine, nevertheless, induces a cytoplasmic membrane complex of 470S (Fig. 1). In a superinfection with ME virus this complex is successively modified into an ME virus-specific membrane complex of 700S depending on the length of superinfection. In cells preinfected with poliovirus for 4 h the complex sediments at 700S after a 6 h superinfection with ME virus (Fig. 1), whereas in a single infection with ME virus the 700S complex is formed not earlier than 8 h post-infection. From this it has been concluded that ME virus is reproduced with a shortened latent period by exploiting the 'poliovirus/guanidine'-induced and preexisting membrane complex for its own reproduction. The present communication shows that the modified complex serves as a site for ME virusspecific RNA synthesis.Growth of HEp-2 cells in monolayer cultures, propagation of poliovirus type 1 (strain Mahoney) and ME virus (laboratory strain), double infection experiments with both viruses and separation of cytoplasmic membrane complexes were performed as descri...

Entry of Poliovirus Type 1 and Mouse Elberfeld (ME) Virus into HEp-2 Cells: Receptor-mediated Endocytosis and Endosomal or Lysosomal Uncoating

“…Our analysis of RNA synthesis of poliovirus and ME virus in vivo at smooth cytoplasmic membranes (Caliguiri & Tamm, 1970;Zeichhardt et al, 1983a) as a virus-specific reaction that follows the base-sensitive step (Fig. 2a, b, e) indicates that the decrease in RNA synthesis was caused by the blockage in the release of the RNA substrate from endosomes and/or lysosomes into the cytoplasm.…”