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Basic Characteristics of Mutations
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Mutation Site
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K279M |
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Mutation Site Sentence
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Notably, our map reveals that the previously proposed receptor binding pocket is surrounded by three mutations: DI-E138K and DII-K279M from one E monomer, and DII-E244G from the other E monomer, with their side chains all oriented toward the center of the pocket, facing either upward or downward. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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E |
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Standardized Encoding Gene
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envelope
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Genotype/Subtype
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- |
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Viral Reference
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KU323483;JN604986
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Functional Impact and Mechanisms
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Disease
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Cell line
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Immune
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- |
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Target Gene
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-
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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39775684
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Title
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Key virulence factors responsible for differences in pathogenicity between clinically proven live-attenuated Japanese encephalitis vaccine SA14-14-2 and its pre-attenuated highly virulent parent SA14
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Author
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Song BH,Yun SI,Goldhardt JL,Kim J,Lee YM
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Journal
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PLoS pathogens
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Journal Info
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2025 Jan 7;21(1):e1012844
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Abstract
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Japanese encephalitis virus (JEV), a neuroinvasive and neurovirulent orthoflavivirus, can be prevented in humans with the SA14-14-2 vaccine, a live-attenuated version derived from the wild-type SA14 strain. To determine the viral factors responsible for the differences in pathogenicity between SA14 and SA14-14-2, we initially established a reverse genetics system that includes a pair of full-length infectious cDNAs for both strains. Using this cDNA pair, we then systematically exchanged genomic regions between SA14 and SA14-14-2 to generate 20 chimeric viruses and evaluated their replication capability in cell culture and their pathogenic potential in mice. Our findings revealed the following: (i) The single envelope (E) protein of SA14-14-2, which contains nine mutations (eight in the ectodomain and one in the stem region), is both necessary and sufficient to render SA14 non-neuroinvasive and non-neurovirulent. (ii) Conversely, the E protein of SA14 alone is necessary for SA14-14-2 to become highly neurovirulent, but it is not sufficient to make it highly neuroinvasive. (iii) The limited neuroinvasiveness of an SA14-14-2 derivative that contains the E gene of SA14 significantly increases (approaching that of the wild-type strain) when two viral nonstructural proteins are replaced by their counterparts from SA14: (a) NS1/1', which has four mutations on the external surface of the core beta-ladder domain; and (b) NS2A, which has two mutations in the N-terminal region, including two non-transmembrane alpha-helices. In line with their roles in viral pathogenicity, the E, NS1/1', and NS2A genes all contribute to the enhanced spread of the virus in cell culture. Collectively, our data reveal for the first time that the E protein of JEV has a dual function: It is the master regulator of viral neurovirulence and also the primary initiator of viral neuroinvasion. After the initial E-mediated neuroinvasion, the NS1/1' and NS2A proteins act as secondary promoters, further amplifying viral neuroinvasiveness.
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Sequence Data
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-
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