Article

Nonstructural proteins NS2-3 and NS4A of classical swine fever virus: essential features for infectious particle formation.

Institute of Virology and Immunoprophylaxis, Sensemattstrasse 293, CH-3147 Mittelhäusern, Switzerland.
Virology (impact factor: 3.35). 10/2007; 365(2):376-89. DOI:10.1016/j.virol.2007.03.056 pp.376-89
Source: PubMed

ABSTRACT The nonstructural protein NS2-3 of pestiviruses undergoes tightly regulated processing. For bovine viral diarrhea virus it was shown that uncleaved NS2-3 is required for infectious particle formation while cleaved NS3 is essential for genome replication. To further investigate the functions of NS2-3 and NS4A in the pestivirus life cycle, we established T7 RNA polymerase-dependent trans-complementation for p7-NS2-3-4A of classical swine fever virus (CSFV). Expression of NS2-3 and NS4A in trans restored the production of infectious particles from genomes lacking NS2-3 expression. Co-expression of cleaved NS4A was essential. None of the enzymatic activities harbored by NS2-3 were required for infectious particle formation. Importantly, expression of uncleavable NS2-3 together with NS4A rescued infectious particles from a genome lacking NS2, demonstrating that cleaved NS2 per se has no additional essential function. These data indicate that NS2-3 and NS3, each in association with NS4A, have independent functions in the CSFV life cycle.

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Keywords

additional essential function
 
bovine viral diarrhea virus
 
classical swine fever virus
 
cleaved NS2
 
Co-expression
 
CSFV
 
CSFV life cycle
 
enzymatic activities harbored
 
functions
 
genome replication
 
independent functions
 
infectious particle formation
 
infectious particles
 
nonstructural protein NS2-3
 
NS2-3 expression
 
pestiviruses undergoes
 
T7 RNA polymerase-dependent trans-complementation
 
trans
 
uncleavable NS2-3
 
uncleaved NS2-3