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J. Virol., Sep 1995, 5516-5527, Vol 69, No. 9
DJ Barton, EP Black and JB Flanegan
Translation of poliovirion RNA in HeLa S10 extracts resulted in the
formation of RNA replication complexes which catalyzed the asymmetric
replication of poliovirus RNA. Synthesis of poliovirus RNA was detected in
unfractionated HeLa S10 translation reactions and in RNA replication
complexes isolated from HeLa S10 translation reactions by pulse- labeling
with [32P]CTP. The RNA replication complexes formed in vitro contained
replicative-intermediate RNA and were enriched in viral protein 3CD and the
membrane-associated viral proteins 2C, 2BC, and 3AB. Genome-length
poliovirus RNA covalently linked to VPg was synthesized in large amounts by
the replication complexes. RNA replication was highly asymmetric, with
predominantly positive-polarity RNA products. Both anti-VPg antibody and
guanidine HCl inhibited RNA replication and virus formation in the HeLa S10
translation reactions without affecting viral protein synthesis. The
inhibition of RNA synthesis by guanidine was reversible. The reversible
nature of guanidine inhibition was used to demonstrate the formation of
preinitiation RNA replication complexes in reaction mixes containing 2 mM
guanidine HCl. Preinitiation complexes sedimented upon centrifugation at
15,000 x g and initiated RNA replication upon their resuspension in
reaction mixes lacking guanidine. Initiation of RNA synthesis by
preinitiation complexes did not require active protein synthesis or the
addition of soluble viral proteins. Initiation of RNA synthesis by
preinitiation complexes, however, was absolutely dependent on soluble HeLa
cytoplasmic factors. Preinitiation complexes also catalyzed the formation
of infectious virus in reaction mixes containing exogenously added capsid
proteins. The titer of infectious virus produced in such
trans-encapsidation reactions reached 4 x 10(7) PFU/ml. The HeLa S10
translation-RNA replication reactions represent an efficient in vitro
system for authentic poliovirus replication, including protein synthesis,
polyprotein processing, RNA replication, and virus assembly.
Copyright © 1995, American Society for Microbiology
Complete replication of poliovirus in vitro: preinitiation RNA replication complexes require soluble cellular factors for the synthesis of VPg-linked RNA
Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville 32610-0266, USA.
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