Japanese Encephalitis DNA Vaccines with Epitope Modification Reduce the Induction of Cross-Reactive Antibodies against Dengue Virus and Antibody-Dependent Enhancement of Dengue Virus Infection.

Infection with viruses belonging to the genus , such as Japanese encephalitis virus (JEV) and dengue virus (DENV), is a worldwide health problem. Vaccines against JEV and DENV are currently available. However, the dengue vaccine possibly increases the risk of severe dengue due to antibody-dependent enhancement (ADE).

Engineered flavivirus vaccines control induction of crossreactive infection-enhancing and -neutralizing antibodies.

Flaviviruses are important human pathogens because of their global distribution and disease severity. The high structural similarity among flaviviruses induces cross-immunity, with individual flaviviruses exhibiting crossreactive infection-enhancing and/or -neutralizing activities against other flaviviruses. Unlike neutralizing antibodies, enhancing antibodies may increase the risk of disease severity.

Antibody-dependent enhancement representing in vitro infective progeny virus titer correlates with the viremia level in dengue patients.

Dengue virus (DENV) causes dengue fever (DF) and dengue hemorrhagic fever in humans. Some DF patients suddenly develop severe symptoms around the defervescent period. Although the pathogenic mechanism of the severe symptoms has not been fully elucidated, the viremia level in the early phase has been shown to correlate with the disease severity.

A potent neutralizing mouse monoclonal antibody specific to dengue virus type 1 Mochizuki strain recognized a novel epitope around the N-67 glycan on the envelope protein: A possible explanation of dengue virus evolution regarding the acquisition of N-67 glycan.

The analysis of neutralizing epitope of dengue virus (DENV) is important for the development of an effective dengue vaccine. A potent neutralizing mouse monoclonal antibody named 7F4 was previously reported and, here, we further analyzed the detailed epitope of this antibody. 7F4 recognized a novel conformational epitope close to the N-67 glycan on the envelope protein.

Cytokine Expression in Dengue Fever and Dengue Hemorrhagic Fever Patients with Bleeding and Severe Hepatitis.

Dengue is the most common mosquito-borne flaviviral infection in the world today. Several factors contribute and act synergistically to cause severe infection. One of these is dysregulated host immunological mediators that cause transient pathophysiology during infection.

Intraperitoneal injection with dengue virus type 1-infected K562 cells results in complete fatality among immunocompetent mice.

Dengue is one of the most important mosquito-borne viral diseases. Over half of the world's population is living in dengue endemic countries, where 100 million cases are estimated to occur annually. Although one dengue vaccine is currently available commercially, unfortunately its safety and efficacy has not been demonstrated for seronegative populations.

Key Amino Acid Substitution for Infection-Enhancing Activity-Free Designer Dengue Vaccines.

Dengue is a globally important disease caused by four serotypes of dengue virus. Dengue vaccine development has been hampered by antigenic cross-reactivity among serotypes, which potentially causes antibody-dependent enhancement of infection and disease severity. Here we found that a single amino acid substitution in the envelope protein at position 87 from aspartic acid to asparagine or at position 107 from leucine to phenylalanine is critical for suppressing the induction of infection-enhancing antibody in a mouse model.

High-throughput neutralization assay for multiple flaviviruses based on single-round infectious particles using dengue virus type 1 reporter replicon.

Diseases caused by the genus Flavivirus, including dengue virus (DENV) and Zika virus (ZIKV), have a serious impact on public health worldwide. Due to serological cross-reactivity among flaviviruses, current enzyme-linked immunosorbent assay (ELISA) for IgM/G cannot reliably distinguish between infection by different flaviviruses. In this study, we developed a reporter-based neutralization assay using single-round infectious particles (SRIPs) derived from representative flaviviruses.

Human monoclonal antibodies against West Nile virus from Japanese encephalitis-vaccinated volunteers.

West Nile virus (WNV) is a positive-sense single-stranded RNA flavivirus belonging to the Japanese encephalitis virus (JEV) serocomplex of the Flaviviridae family and causes mosquito-borne infections. Although most human infection cases are asymptomatic, approximately one in 150 infected individuals develops meningoencephalitis, with a mortality rate of 4-14%. While the development of human neutralizing antibody therapeutics against WNV is strongly anticipated, WNV is difficult to study in conventional laboratories due to its high safety level requirement.

Dengue-Immune Humans Have Higher Levels of Complement-Independent Enhancing Antibody than Complement-Dependent Neutralizing Antibody.

Dengue is the most important arboviral disease worldwide. We previously reported that most inhabitants of dengue-endemic countries who are naturally immune to the disease have infection-enhancing antibodies whose in vitro activity does not decrease in the presence of complement (complement-independent enhancing antibodies, or CiEAb). Here, we compared levels of CiEAb and complement-dependent neutralizing antibodies (CdNAb) in dengue-immune humans.

Utility of Japanese encephalitis virus subgenomic replicon-based single-round infectious particles as antigens in neutralization tests for Zika virus and three other flaviviruses.

The introduction of a foreign virus into an area may cause an outbreak, as with the Zika virus (ZIKV) outbreak in the Americas. Preparedness for handling a viral outbreak involves the development of tests for the serodiagnosis of foreign virus infections. We previously established a gene-based technology to generate some flaviviral antigens useful for functional antibody assays.

Neutralizing and enhancing antibody responses to five genotypes of dengue virus type 1 (DENV-1) in DENV-1 patients.

Dengue virus (DENV) has four distinct serotypes, DENV-1-4, with four to six genotypes in each serotype. The World Health Organization recommends tetravalent formulations including one genotype of each serotype as safe and effective dengue vaccines. Here, we investigated the impact of genotype on the neutralizing antibody responses to DENV-1 in humans.

Complement-independent dengue virus type 1 infection-enhancing antibody reduces complement-dependent and -independent neutralizing antibody activity.

Dengue fever and dengue hemorrhagic fever are globally important mosquito-transmitted viral diseases. However, the only licensed vaccine is not highly protective. Viremia is related to disease severity in infected humans, and it is thought to be reduced by neutralizing antibodies but increased by infection-enhancing antibodies.

Unique Requirement for ESCRT Factors in Flavivirus Particle Formation on the Endoplasmic Reticulum.

Flavivirus infection induces endoplasmic reticulum (ER) membrane rearrangements to generate a compartment for replication of the viral genome and assembly of viral particles. Using quantitative mass spectrometry, we identified several ESCRT (endosomal sorting complex required for transport) proteins that are recruited to sites of virus replication on the ER. Systematic small interfering RNA (siRNA) screening revealed that release of both dengue virus and Japanese encephalitis virus was dramatically decreased by single depletion of TSG101 or co-depletion of specific combinations of ESCRT-III proteins, resulting in ≥1,000-fold titer reductions.

Bivalent vaccine platform based on Japanese encephalitis virus (JEV) elicits neutralizing antibodies against JEV and hepatitis C virus.

Directly acting antivirals recently have become available for the treatment of hepatitis C virus (HCV) infection, but there is no prophylactic vaccine for HCV. In the present study, we took advantage of the properties of Japanese encephalitis virus (JEV) to develop antigens for use in a HCV vaccine. Notably, the surface-exposed JEV envelope protein is tolerant of inserted foreign epitopes, permitting display of novel antigens.

Production of Japanese Encephalitis Virus-Like Particles Using Insect Cell Expression Systems.

Virus-like particles (VLPs) can be produced via the expression of virus surface proteins that self-assemble into particulate structures in recombinant protein expression systems. Expression of the DNA fragment encoding the Japanese encephalitis (JE) virus prM signal peptide, the precursor (prM) of the viral membrane protein (M), and the envelope glycoprotein (E) allows the production of a secretory form of VLPs. Expression systems that use lepidopteran insect cells, such as the baculovirus-insect cell system and stably transformed insect cells, can be used for the efficient production of JE VLPs.

Strategies to improve the immunogenicity of prM+E dengue virus type-2 DNA vaccine.

Background: An important goal for dengue vaccines is to induce a high and durable level of neutralizing antibody.

Objective: Three strategies were investigated for improving the immunogenicity of a prM+E dengue serotype 2 (DENV-2) DNA vaccine: 1) expression in two different plasmids; 2) adjustment of dose; and, 3) introduction of the E sequence of Japanese encephalitis virus (JEV) at the carboxy-terminal portion of DENV-2 E.

Method: Expression cassettes were designed to encode a full-length prM+E sequence of DENV-2 virus employing human-preferred codons (D2prMEopt), or a chimeric prM+E sequence in which the 100-residue carboxy-terminal region of E was derived from JEV (D2prMEJE20opt).

Dengue virus infection-enhancing antibody activities against Indonesian strains in inhabitants of central Thailand.

Dengue virus (DENV) infection-enhancing antibodies are a hypothetic factor to increase the dengue disease severity. In this study, we investigated the enhancing antibodies against Indonesian strains of DENV-1-4 in 50 healthy inhabitants of central Thailand (Bangkok and Uthai Thani). Indonesia and Thailand have seen the highest dengue incidence in Southeast Asia.

Divergence of the dengue virus type 2 Cosmopolitan genotype associated with two predominant serotype shifts between 1 and 2 in Surabaya, Indonesia, 2008-2014.

Indonesia is one of the biggest dengue endemic countries, and, thus, is an important place to investigate the evolution of dengue virus (DENV). We have continuously isolated DENV in Surabaya, the second biggest city in Indonesia, since 2008. We previously reported sequential changes in the predominant serotype from DENV type 2 (DENV-2) to DENV type 1 (DENV-1) in November 2008 and from DENV-1 to DENV-2 in July 2013.

Expression of enhancing-activity-free neutralizing antibody against dengue type 1 virus in plasmid-inoculated mice.

Background: Most candidate dengue vaccines currently under development induce neutralizing antibodies, which are considered important for immunoprotection. However, the concomitant induction of infection-enhancing antibodies is an unavoidable concern. In contrast, a neutralizing antibody developed for passive immunotherapy has been engineered to eliminate its enhancing activity.

Potential chemotherapeutic targets for Japanese encephalitis: current status of antiviral drug development and future challenges.

Introduction: Japanese encephalitis (JE) remains a public health threat in Asia. Although several vaccines have been licensed, ∼ 67,900 cases of the disease are estimated to occur annually, probably because the vaccine coverage is low. Therefore, effective antiviral drugs are required to control JE.

Double Lynden-Bell structure of low-energy quasistationary distributions in the Hamiltonian mean-field model.

In the Hamiltonian mean-field model, we study the core-halo structure of low-energy quasistationary states under unsteady water-bag type initial conditions. The core-halo structure results in the superposition of two independent Lynden-Bell distributions. We examine the completeness of the Lynden-Bell relaxation and the relaxation between these two Lynden-Bell distributions.

Immunogenicity of a Candidate DNA Vaccine Based on the prM/E Genes of a Dengue Type 2 Virus Cosmopolitan Genotype Strain.

The development of a dengue virus vaccine is a major priority in efforts to control the diseases. Several researchers are currently using the Asian 1 and Asian 2 genotypes as vaccine candidates for dengue type 2 virus (DENV-2). However, in this study, we constructed a recombinant plasmid-based prM/E gene, from a DENV-2 Cosmopolitan genotype strain as a dengue DNA vaccine candidate.

Continuous dengue type 1 virus genotype shifts followed by co-circulation, clade shifts and subsequent disappearance in Surabaya, Indonesia, 2008-2013.

Four serotypes of dengue virus (DENV-1 to DENV-4) and their genotypes are distributed in tropical and subtropical regions. Indonesia has been recently suggested as the origin of some dengue virus genotypes. In Surabaya, the second biggest city of Indonesia, we previously reported a shift of the predominantly circulating serotype from DENV-2 to DENV-1 in November 2008, followed by a genotype shift of DENV-1 from genotype IV (GIV) to genotype I (GI) in September 2009, based on nucleotide sequences in the envelope protein coding region.