Disease relevance of nsP2

• Although the alphavirus nonstructural protein 2 (nsP2) is an essential component of the viral replication complex, it also has critical auxiliary functions that determine the outcome of infection in the host [1].
• To gain a better understanding of nsP2 function, we sought to identify cellular proteins with which Venezuelan equine encephalitis virus nsP2 interacted [1].
• Mutations in nsP2 can also attenuate Sindbis virus cytopathogenicity [2].
• Deletion analysis of a defective interfering Semliki Forest virus RNA genome defines a region in the nsP2 sequence that is required for efficient packaging of the genome into virus particles [3].

High impact information on nsP2

• Site 2/3 was cleaved rapidly in trans but only after release of nsP1 from the polyprotein exposing an "activator" sequence present in the amino terminus of nsP2 [4].
• Late in infection free nsP2 would cleave at site 2/3 yielding P12 and P34, the products of which, nsP1-4, are distributed to the plasma membrane, nucleus, cytoplasmic aggregates, and proteasomes, respectively [4].
• SDV infectious cDNA was used for two kinds of experiments (i) to evaluate the impact of various targeted mutations in nsP2 on viral replication and (ii) to study the virulence of rSDV in trout [5].
• Five different nsP2 PI replicons were compared to wild-type (wt) SIN, SFV, and wt nsPs SIN replicons [6].
• Taken together, the results suggest the complex nature of interactions between nsP2, nsP3, the 5' UTR, and host-specific protein factors binding to the 51-nt CSE and involved in RdRp formation [7].

Chemical compound and disease context of nsP2

• Roles of nonstructural protein nsP2 and Alpha/Beta interferons in determining the outcome of Sindbis virus infection [2].

Biological context of nsP2

• Minus-strand synthesis and incorporation of [3H]uridine into replicative intermediates differed among PI replicons, depending on the location of the mutation in nsP2 [6].
• From their similar phenotypes, we predict that other nsP2 N-domain mutants are blocked also in the conversion of RCinitial to RCstable [8].
• In this report, we demonstrate that a viral nonstructural protein, nsP2, is a significant regulator of Sindbis virus-host cell interactions [2].
• We identified mutations in the gene for nsP2, a nonstructural protein of the alphavirus Sindbis virus, that appear to block the conversion of the initial, short-lived minus-strand replicase complex (RCinitial) into mature, stable forms that are replicase and transcriptase complexes (RCstable), producing 49S genome or 26S mRNA [8].
• Infection of murine cells with Sindbis virus expressing a mutant nsP2 leads to higher levels of IFN secretion and the activation of 170 cellular genes that are induced by IFN and/or virus replication [2].

Anatomical context of nsP2

• The SIN-83 virus, which contained an additional adaptive mutation in the nsP2 gene, replicated efficiently in common cell lines and did not cause detectable disease in adult or suckling mice after either i.c. or s.c. inoculation [9].
• In both wild-type- and mutant-virus-infected cells, SFV nsP3 and nsP4 could be extracted from membranes only by alkaline solutions whereas the nsP2-membrane association was looser [10].
• Blocking of IFN-alpha/beta signaling makes mouse fibroblasts unable to stop replication of Sindbis virus (SINV) with mutated nsP2 and leads to persistent infection [11].

Associations of nsP2 with chemical compounds

• Cleavage of P23 or other modifications to nsP2 and nsP4 convert the initial transcription complex to a stable complex that synthesizes positive strands [12].

Other interactions of nsP2

• Reactivation of negative-strand synthesis by mutations in nsP2 resembled that in nsP4: it was a reversible property of stable replication complexes and did not require continuation of viral protein synthesis [13].

References