Potential Protective Effect of Dengue NS1 Human Monoclonal Antibodies against Dengue and Zika Virus Infections

Differences in the Membrane-Binding Properties of Flaviviral Nonstructural 1 (NS1) Protein: Comparative Simulations of Zika and Dengue Virus NS1 Proteins in Explicit Bilayers

NS1 in flaviviruses is the only nonstructural protein that is secretory and interacts with different cellular components of the host cell membrane. NS1 is localized in the ER as a dimer to facilitate viral replication. Crystal structures of NS1 homologues from zika (ZIKV) and dengue (DENV) viruses have revealed the organization of different domains in NS1 dimers. The β-roll and the connector and intertwined loop regions of wing domains of NS1 have been shown to interact with the membranes. In this study, we have performed multiple molecular dynamics (MD) simulations of ZIKV and DENV NS1 systems in apo and in POPE bilayers with different cholesterol concentrations (0, 20 and 40%). The NS1 protein was placed just above the membrane surface, and for each NS1-membrane system two to three independent simulations with 600 ns production run were performed. At the end of the production runs, ZIKV NS1 inserts deeper inside the membrane compared to the DENV counterpart. Unlike ZIKV NS1, the orientation of DENV NS1 is asymmetric in which one of the chains in the dimer interacts with the membrane while the other is more exposed to the solvent. The β-roll region in ZIKV NS1 penetrates beyond the headgroup region and interacts with the lipid acyl chains while the C-terminal region barely interacts with the headgroup. Specific residues in the intertwined region deeply penetrate inside the membrane. The role of charged and aromatic residues of ZIKV NS1 in strongly interacting with the membrane components is revealed. The presence of cholesterol affects the extent of insertion in the membrane and interaction of individual residues. Overall, membrane-binding properties of ZIKV NS1 significantly differ from its counterpart in DENV. The differences found in the binding and insertion of NS1 can be used to design drugs and novel antibodies that can be flavivirus specific.

Nicotiana benthamiana as a potential source for producing anti-dengue virus D54 neutralizing therapeutic antibody

Dengue virus (DENV), transmitted by mosquitoes, is classified into four serotypes (DENV1-4) and typically causes mild, self-limiting symptoms upon initial infection. However, secondary infection can lead to severe symptoms due to antibody-dependent enhancement (ADE). To address this, anti-DENV antibodies are being developed with the goal of neutralizing infection without ADE activity. Previous attempts using a 54_hG1 antibody from CHO-K1 mammalian cells resulted in ADE induction, increasing viral infection. This study aimed to express the D54 monoclonal antibody in Nicotiana benthamiana. The plant-produced antibody had a similar neutralizing profile to the previous 54_hG1 antibody. Notably, the ADE activities of the plant-derived antibody were successfully eliminated, with no sign of viral induction. These findings suggest that N. benthamiana could be a source of therapeutic DENV antibodies. The method offers several advantages, including lower ADE, cost-effectiveness, simple facility requirements, scalability, and potential industrial-scale production in GMP facilities.

The Adaptive Immune Response against Bunyavirales

The Bunyavirales order includes at least fourteen families with diverse but related viruses, which are transmitted to vertebrate hosts by arthropod or rodent vectors. These viruses are responsible for an increasing number of outbreaks worldwide and represent a threat to public health. Infection in humans can be asymptomatic, or it may present with a range of conditions from a mild, febrile illness to severe hemorrhagic syndromes and/or neurological complications. There is a need to develop safe and effective vaccines, a process requiring better understanding of the adaptive immune responses involved during infection. This review highlights the most recent findings regarding T cell and antibody responses to the five Bunyavirales families with known human pathogens (Peribunyaviridae, Phenuiviridae, Hantaviridae, Nairoviridae, and Arenaviridae). Future studies that define and characterize mechanistic correlates of protection against Bunyavirales infections or disease will help inform the development of effective vaccines.

Aged AG129 mice support the generation of highly virulent novel mouse-adapted DENV (1-4) viruses exhibiting neuropathogenesis and high lethality

Dengue virus infection in humans ranges from asymptomatic infection to severe infection, with ∼2.5 % overall disease fatality rate. Evidence of neurological manifestations is seen in the severe form of the disease, which might be due to the direct invasion of the viruses into the CNS system but is poorly understood. In this study, we demonstrated that the aged AG129 mice are highly susceptible to dengue serotypes 1-4, and following the adaptation, this resulted in the generation of neurovirulent strains that showed enhanced replication, aggravated disease severity, increased neuropathogenesis, and high lethality in both adult and aged AG129 mice. The infected mice had endothelial dysfunction, elicited pro-inflammatory cytokine responses, and exhibited 100 % mortality. Further analysis revealed that aged-adapted DENV strains induced measurable alterations in TLR expression in the aged mice as compared to the adult mice. In addition, metabolomics analysis of the serum samples from the infected adult mice revealed dysregulation of 18 metabolites and upregulation of 6-keto-prostaglandin F1 alpha, phosphocreatine, and taurocholic acid. These metabolites may serve as key biomarkers to decipher and comprehend the severity of dengue-associated severe neuro-pathogenesis.

Polyvalent passive vaccine candidates from egg yolk antibodies (IgY) of important outer membrane proteins (PF1380 and ExbB) of Pseudomonas fluorescens in fish

Polyvalent antibodies can resist multiple bacterial species, and immunoglobulin Y (IgY) antibody can be economically prepared in large quantities from egg yolk; further, IgY polyvalent antibodies have application value in aquaculture. The outer membrane proteins (OMPs) PF1380 and ExbB of Pseudomonas fluorescens were expressed and purified, and the corresponding IgY antibodies were prepared. PF1380, ExbB, and the corresponding IgY antibodies could activate the innate immune responses of chicken and Carassius auratus. The passive immunization to C. auratus showed that the IgY antibodies of PF1380 and ExbB had an immune protection rate, down-regulated the expression of antioxidant-related factors (MDA, SOD, GSH-Px, and CAT) to reduce the antioxidant reaction, down-regulated the expression of inflammation-related genes (IL-6, IL-8, TNF-α, and IL-1β) to reduce the inflammatory reaction, maintained the integrity of visceral tissue structure, and reduced apoptosis and damage of tissue cells in relation to P. fluorescens and Aeromonas hydrophila infections. Thus, the IgY antibodies of PF1380 and ExbB could be considered as passive polyvalent vaccine candidates in aquaculture.

Arthropod-Borne Flaviviruses in Pregnancy

Flaviviruses are a diverse group of enveloped RNA viruses that cause significant clinical manifestations in the pregnancy and postpartum periods. This review highlights the epidemiology, pathophysiology, clinical features, diagnosis, and prevention of the key arthropod-borne flaviviruses of concern in pregnancy and the neonatal period-Zika, Dengue, Japanese encephalitis, West Nile, and Yellow fever viruses. Increased disease severity during pregnancy, risk of congenital malformations, and manifestations of postnatal infection vary widely amongst this virus family and may be quite marked. Laboratory confirmation of infection is complex, especially due to the reliance on serology for which flavivirus cross-reactivity challenges diagnostic specificity. As such, a thorough clinical history including relevant geographic exposures and prior vaccinations is paramount for accurate diagnosis. Novel vaccines are eagerly anticipated to ameliorate the impact of these flaviviruses, particularly neuroinvasive disease manifestations and congenital infection, with consideration of vaccine safety in pregnant women and children pivotal. Moving forward, the geographical spread of flaviviruses, as for other zoonoses, will be heavily influenced by climate change due to the potential expansion of vector and reservoir host habitats. Ongoing 'One Health' engagement across the human-animal-environment interface is critical to detect and responding to emergent flavivirus epidemics.