Mutagenesis of Dengue Virus Protein NS2A Revealed a Novel Domain Responsible for Virus-Induced Cytopathic Effect and Interactions between NS2A and NS2B Transmembrane Segments

Wu, Ren Huang; Tsai, Ming Han; Tsai, Kuen Nan; Tian, Jia Ni; Wu, Jian; Wu, Su Ying; Chern, Jyh Haur; Chen, Chun Hong; Yueh, Andrew

doi:10.1128/jvi.01836-16

Cited by 35 publications

(29 citation statements)

References 37 publications

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“…Moreover, scanning mutagenesis studies of NS2A implicated that the intermolecular interactions between pTMSs are critical in a DENV life cycle (25,33). Mutations of multiple conserved residues in different pTMSs, which are located inside or outside the ER lumen or within the ER membrane, showed different defect patterns (25,33). K135 of NS2A is predicted to locate in pTMS5 at the lumen side of ER (30), which possibly involves NS2A VSR function by mediating pTMS interactions.…”

Section: Discussionmentioning

confidence: 99%

Flavivirus induces and antagonizes antiviral RNA interference in both mammals and mosquitoes

Qiu

Wang

et al. 2020

Sci. Adv.

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Mosquito-borne flaviviruses infect both mammals and mosquitoes. RNA interference (RNAi) has been demonstrated as an anti-flavivirus mechanism in mosquitoes; however, whether and how flaviviruses induce and antagonize RNAi-mediated antiviral immunity in mammals remains unknown. We show that the nonstructural protein NS2A of dengue virus-2 (DENV2) act as a viral suppressor of RNAi (VSR). When NS2A-mediated RNAi suppression was disabled, the resulting mutant DENV2 induced Dicer-dependent production of abundant DENV2-derived siRNAs in differentiated mammalian cells. VSR-disabled DENV2 showed severe replication defects in mosquito and mammalian cells and in mice that were rescued by RNAi deficiency. Moreover, NS2As of multiple flaviviruses act as VSRs in vitro and during viral infection in both organisms. Overall, our findings demonstrate that antiviral RNAi can be induced by flavivirus, while flavivirus uses NS2A as a bona fide VSR to evade RNAi in mammals and mosquitoes, highlighting the importance of RNAi in flaviviral vector-host life cycles.

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Section: Discussionmentioning

confidence: 99%

Flavivirus induces and antagonizes antiviral RNA interference in both mammals and mosquitoes

Qiu

Wang

et al. 2020

Sci. Adv.

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“…It is also reported that the N-terminal half of NS2a protein of dengue virus 2 is implicated in causing cytopathic effect (CPE) due to virus, whereas the C-terminal portion takes part in assembly of virus particle and subsequent secretion from the cell. This fact can be exploited for development of vaccines and drugs against dengue infection ( 46 ). NS2b is a 14 kDa membrane-associated protein.…”

Section: Dengue Virus Proteinsmentioning

confidence: 99%

Recent Developments in Recombinant Protein–Based Dengue Vaccines

Tripathi

Shrivastava

2018

Front. Immunol.

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Recombinant proteins are gaining enormous importance these days due to their wide application as biopharmaceutical products and proven safety record. Various recombinant proteins of therapeutic and prophylactic importance have been successfully produced in microbial and higher expression host systems. Since there is no specific antiviral therapy available against dengue, the prevention by vaccination is the mainstay in reducing the disease burden. Therefore, efficacious vaccines are needed to control the spread of dengue worldwide. Dengue is an emerging viral disease caused by any of dengue virus 1–4 serotypes that affects the human population around the globe. Dengue virus is a single stranded RNA virus encoding three structural proteins (capsid protein, pre-membrane protein, and envelope protein) and seven non-structural proteins (NS1, NS2a, NS2b, NS3, NS4a, NS4b, NS5). As the only licensed dengue vaccine (Dengvaxia) is unable to confer balanced protection against all the serotypes, therefore various approaches for development of dengue vaccines including tetravalent live attenuated, inactivated, plasmid DNA, virus-vectored, virus-like particles, and recombinant subunit vaccines are being explored. These candidates are at different stages of vaccine development and have their own merits and demerits. The promising subunit vaccines are mainly based on envelope or its domain and non-structural proteins of dengue virus. These proteins have been produced in different hosts and are being investigated for development of a successful dengue vaccine. Novel immunogens have been designed employing various strategies like protein engineering and fusion of antigen with various immunostimulatory motif to work as self-adjuvant. Moreover, recombinant proteins can be formulated with novel adjuvants to enhance the immunogenicity and thus conferring better protection to the vaccinees. With the advent of newer and safer host systems, these recombinant proteins can be produced in a cost effective manner at large scale for vaccine studies. In this review, we summarize recent developments in recombinant protein based dengue vaccines that could lead to a good number of efficacious vaccine candidates for future human use and ultimately alternative dengue vaccine candidates.

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“…The flavivirus nonstructural protein NS2A is a nonenzymatic, integral membrane protein (20). In addition to playing an important role in viral RNA replication (21), NS2A also performs an essential role in virus assembly (3,(22)(23)(24). Previous studies revealed that NS2A interacts with NS2B in mammalian cells (12,13,24).…”

Section: Fig 10mentioning

confidence: 99%

Host Factor SPCS1 Regulates the Replication of Japanese Encephalitis Virus through Interactions with Transmembrane Domains of NS2B

Zhang

et al. 2018

J Virol

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Signal peptidase complex subunit 1 (SPCS1) is a newly identified host factor that regulates flavivirus replication, but the molecular mechanism is not fully understood. Here, using Japanese encephalitis virus (JEV) as a model, we investigated the mechanism through which the host factor SPCS1 regulates the replication of flaviviruses. We first validated the regulatory function of SPCS1 in JEV propagation by knocking down and knocking out endogenous SPCS1. The loss of SPCS1 function markedly reduced intracellular virion assembly and the production of infectious JEV particles but did not affect cell entry, RNA replication, or translation of the virus. SPCS1 was found to interact with nonstructural protein 2B (NS2B), which is involved in posttranslational protein processing and virus assembly. Serial deletion mutation of the JEV NS2B protein revealed that two transmembrane domains, NS2B(1-49) and NS2B(84-131), interact with SPCS1. Further mutagenesis analysis of conserved flavivirus residues in two SPCS1 interaction domains of NS2B demonstrated that G12A, G37A, and G47A in NS2B(1-49) and P112A in NS2B(84-131) weakened the interaction with SPCS1. Deletion mutation of SPCS1 revealed that SPCS1(91-169), which contains two transmembrane domains, was involved in interactions with both NS2B(1-49) and NS2B(84-131). Taken together, these results demonstrate that SPCS1 affects viral replication by interacting with NS2B, thereby influencing the posttranslational processing of JEV proteins and the assembly of virions. Understanding virus-host interactions is important for elucidating the molecular mechanisms of virus propagation and identifying potential antiviral targets. Previous reports demonstrated that SPCS1 is involved in the flavivirus life cycle, but the mechanism remains unknown. In this study, we confirmed that SPCS1 participates in the posttranslational protein processing and viral assembly stages of the JEV life cycle but not in the cell entry, genome RNA replication, or translation stages. Furthermore, we found that SPCS1 interacts with two independent transmembrane domains of the flavivirus NS2B protein. NS2B also interacts with NS2A, which is proposed to mediate virus assembly. Therefore, we propose a protein-protein interaction model showing how SPCS1 participates in the assembly of JEV particles. These findings expand our understanding of how host factors participate in the flavivirus replication life cycle and identify potential antiviral targets for combating flavivirus infection.

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Mutagenesis of Dengue Virus Protein NS2A Revealed a Novel Domain Responsible for Virus-Induced Cytopathic Effect and Interactions between NS2A and NS2B Transmembrane Segments

Cited by 35 publications

References 37 publications

Flavivirus induces and antagonizes antiviral RNA interference in both mammals and mosquitoes

Flavivirus induces and antagonizes antiviral RNA interference in both mammals and mosquitoes

Recent Developments in Recombinant Protein–Based Dengue Vaccines

Host Factor SPCS1 Regulates the Replication of Japanese Encephalitis Virus through Interactions with Transmembrane Domains of NS2B

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