A single amino acid substitution in the NS4B protein of Dengue virus confers enhanced virus growth and fitness in human cells in vitro through IFN-dependent host response

Abstract

Dengue virus (DENV) replication between mosquito and human hosts is hypothesized to be associated with viral determinants that interact in a differential manner between hosts. However, the understanding of inter-host viral determinants that drive DENV replication and growth between hosts is limited. Through the use of clinical isolates, we identified an amino acid variation of Ala, Met and Val at position 116 of DENV-1 NS4B. While the proportion of virus with the NS4B-116V variant remained constantly high in serial passages in a mosquito cell line, populations of the NS4B-116M and NS4B-116A variants became dominant after serial passages in mammalian cell lines. Using recombinant DENV-1 viruses, the Val to Ala or Met alteration at position NS4B-116 (rDENV-1-NS4B-116A and rDENV-1-NS4B-116M) resulted in enhanced virus growth in human cells in comparison to the clone with Val at NS4B-116 (rDENV-1-NS4B-116V). However, the reverse phenomenon was observed in a mosquito cell line. Additionally, in a human cell line, differential levels of IFN-α/β and IFN-stimulated gene expressions (IFIT3, IFI44L, OAS1) suggested that the enhanced viral growth was dependent on the ability of the NS4B protein to hamper host IFN response during the early phase of infection. Overall, we identified a novel and critical viral determinant at the pTMD3 of NS4B region that displayed differential effects on DENV replication and fitness in human and mosquito cell lines. Taken together, the results suggest the importance of the NS4B protein in virus replication and adaptation between hosts.

An Epidemic of Dengue Virus Serotype-4 during the 2015 - 2017: the Emergence of a Novel Genotype IIa of DENV-4 in the Philippines

“…Image processing and base calling were generated as FASTQ files. Quality assessment was performed using the Miseq control software, in which samples with a Q score of >30 were used for further analyses (20). Phylogenetic analyses and molecular dating: Low-quality sequences were removed by FASTX-Toolkit Ver 0.0.14 (21) from the input data file.…”

NS5-V372A and NS5-H386Y variations are responsible for differences in interferon α/β induction and co-contribute to the replication advantage of Japanese encephalitis virus genotype I over genotype III in ducklings

“…For example, ZIKV antagonizes interferon-β (IFN-β) induction via an evolutionary NS1 mutation, thereby promoting replication efficiency in mosquitoes and enhancing neurovirulence in mammals[ 26 ]. A single amino acid substitution in NS4B of DENV enhances virus growth and fitness in human cells in vitro through an IFN-dependent host response[ 27 ]. For JEV, the replication efficiency and virulence positively correlate with the ability to inhibit the IFN-I mediated antiviral response[ 28 ].…”

RIPK3 Promotes JEV Replication in Neurons via Downregulation of IFI44L

“…Recently, Robinson et al (2018) also showed that the failure to induce IFI44L contributed to the long-term propagation of ZIKV in germ cells. The expression of ISGs, including IFI44L, OAS1, and IFIT3, was downregulated by the NS4B protein of dengue virus (DENV) in human cells and thus resulted in high viral replication, which was an immune evasion strategy for DENV (Bui et al, 2018). In this study, a series of ISGs were increased in RIPK3 −/− mouse brains after JEV infection, among which IFI44L was increased most significantly compared with that in the WT.…”