Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of plasmid-based rescue systems for influenza virus has allowed previous studies of the neuraminidase (NA) virion RNA (vRNA) promoter to be extended, in order to test the hypothesis that alternative base pairs in the conserved influenza virus vRNA promoter cause attenuation when introduced into other gene segments. Influenza A/WSN/33 viruses with alternative base pairs in the duplex region of the vRNA promoter of either the polymerase acidic (PA) or the NS (non-structural 1, NS1, and nuclear export, NEP, -encoding) gene have been rescued. Virus growth in MDBK cells demonstrated that one of the mutations, the D2 mutation (U-A replacing G-C at nucleotide positions 12'-11), caused significant virus attenuation when introduced into either the PA or the NS gene. The D2 mutation resulted in the reduction of PA- or NS-specific vRNA and mRNA levels in PA- or NS-recombinant viruses, respectively. Since the D2 mutation attenuates influenza virus when introduced into either the PA or the NS gene segments, or the NA gene segment, as demonstrated previously, this suggests that this mutation will lead to virus attenuation when introduced into any of the eight gene segments. Such a mutation may be useful in the production of live-attenuated viruses.
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PMID:Alternative base pairs attenuate influenza A virus when introduced into the duplex region of the conserved viral RNA promoter of either the NS or the PA gene. 1260

The NS2 (NEP) protein of influenza A virus contains a highly conserved nuclear export signal (NES) motif in its amino-terminal region (12ILMRMSKMQL21, A/WSN/33), which is thought to be required for nuclear export of viral ribonucleoprotein complexes (vRNPs) mediated by a cellular export factor, CRM1. However, simultaneous replacement of three hydrophobic residues in the NES with alanine does not affect NS2 (NEP) binding to CRM1, although the virus with these mutations is not viable. To determine the extent of sequence conservation required by the NS2 (NEP) NES for its export function during viral replication, we randomly introduced mutations by degenerative mutagenesis into the region of NS cDNA encoding the NS2 (NEP) NES and then attempted to generate mutant viruses containing these alterations by reverse genetics. Sequence analysis of the recovered viruses showed that although some of the mutants possessed amino acids other than those conserved in the NES, hydrophobicity within this motif was maintained. Nuclear export of vRNPs representing all of the mutant viruses was completely inhibited in the presence of a CRM1 inhibitor, leptomycin B, as was the transport of wild-type virus, indicating that the CRM1-mediated pathway is responsible for the nuclear export of both wild-type and mutant vRNPs. The vRNPs of some of the mutant viruses were exported in a delayed manner, resulting in limited viral growth in cell culture and in mice. These results suggest that the NES motif may be an attractive target for the introduction of attenuating mutations in the production of live vaccine viruses.
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PMID:Generation of influenza A virus NS2 (NEP) mutants with an altered nuclear export signal sequence. 1533 47

Segment NS in all human influenza A viruses and in the part of avian and animal ones was found to contain an additional (beside NS1 and NEP) long open reading frame (ORF) enabling to code a polypeptide of 18-26 kD in different strains. This ORF, in contrast to the NS1 and NEP, locates in positive sense orientation in the negative polarity genomic NS RNA segment and the encoded protein is referred NSP (Negative Strand Protein). Here, the NSP gene of human influenza A/WSN/33 (H1N1) virus was inserted into genomic DNA of baculovirus (insect nuclear polyhedrosis virus) and insect H5 cells (ovary cell line of Trichoplusia ni) were infected with the obtained chimeric virus. The NSP gene appeared to express 19 kD polypeptide which was intracellularly stable and accumulated predominantly in the cytoplasm of infected H5 cells. These data indicate that the NSP gene possesses sense sequence which is able to direct a physiological synthesis of stable protein in eukaryotic cells.
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PMID:[Integration of influenza A virus NSP gene into baculovirus genome and its expression in insect cells]. 2045 63