Affiliation:
1. Institute of Virology and Cell Biology, University of Lübeck, Lübeck, Germany
Abstract
ABSTRACT
A peculiarity of the
Flaviviridae
is the critical function of nonstructural (NS) proteins for virus particle formation. For pestiviruses, like bovine viral diarrhea virus (BVDV), uncleaved NS2-3 represents an essential factor for virion morphogenesis, while NS3 is an essential component of the viral replicase. Accordingly, in natural pestivirus isolates, processing at the NS2-3 cleavage site is not complete, to allow for virion morphogenesis. Virion morphogenesis of the related hepatitis C virus (HCV) shows a major deviation from that of pestiviruses: while RNA replication also requires free NS3, virion formation does not depend on uncleaved NS2-NS3. Recently, we described a BVDV-1 chimera based on strain NCP7 encompassing the NS2-4B*-coding region of strain Osloss (E. Lattwein, O. Klemens, S. Schwindt, P. Becher, and N. Tautz, J Virol 86:427–437, 2012, doi:10.1128/JVI.06133-11). This chimera allowed for the production of infectious virus particles in the absence of uncleaved NS2-3. The Osloss sequence deviates in the NS2-4B* part from NCP7 in 48 amino acids and also has a ubiquitin insertion between NS2 and NS3. The present study demonstrates that in the NCP7 backbone, only two amino acid exchanges in NS2 (E1576V) and NS3 (V1721A) are sufficient and necessary to allow for efficient NS2-3-independent virion morphogenesis. The adaptation of a bicistronic virus encompassing an internal ribosomal entry site element between the NS2 and NS3 coding sequences to efficient virion morphogenesis led to the identification of additional amino acids in E2, NS2, and NS5B that are critically involved in this process. The surprisingly small requirements for approximating the packaging schemes of pestiviruses and HCV with respect to the NS2-3 region is in favor of a common mechanism in an ancestral virus.
IMPORTANCE
For positive-strand RNA viruses, the processing products of the viral polyprotein serve in RNA replication as well as virion morphogenesis. For bovine viral diarrhea virus, nonstructural protein NS2-3 is of critical importance to switch between these processes. While free NS3 is essential for RNA replication, uncleaved NS2-3, which accumulates over time in the infected cell, is required for virion morphogenesis. In contrast, the virion morphogenesis of the related hepatitis C virus is independent from uncleaved NS2-NS3. Here, we demonstrate that pestiviruses can adapt to virion morphogenesis in the absence of uncleaved NS2-3 by just two amino acid exchanges. While the mechanism behind this gain of function remains elusive, the fact that it can be achieved by such minor changes is in line with the assumption that an ancestral virus already used this mechanism but lost it in the course of adapting to a new host/infection strategy.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Reference59 articles.
1. Pletnev A, Gould E, Heinz FX, Meyers G, Thiel H-J, Bukh J, Stiasny K, Collett MS, Becher P, Simmonds P, Rice CM, Monath TP. 2011. Flaviviridae, p 1003–1020. In King AMQ, Adams MJ, Carstens EB, Lefkowitz EJ (ed), Virus taxonomy. Ninth report of the International Committee on Taxonomy of Viruses. Elsevier Inc., Oxford, United Kingdom.
2. The GB viruses: a review and proposed classification of GBV-A, GBV-C (HGV), and GBV-D in genus Pegivirus within the family Flaviviridae
3. The Molecular Biology of Pestiviruses
4. Lindenbach BD, Murray CL, Thiel HJ, Rice CM. 2013. Flaviviridae, p 712–746. In Knipe DM, Howley PM (ed), Fields virology, 6th ed, vol 1. Lippincott Williams & Wilkins, Philadelphia, PA.
5. A New Type of Signal Peptidase Cleavage Site Identified in an RNA Virus Polyprotein
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献