Dengue and Zika Viruses: Epidemiological History, Potential Therapies, and Promising Vaccines

A novel vaccine construct against Zika virus fever: insights from epitope-based vaccine discovery through molecular modeling and immunoinformatics approaches

The Zika virus (ZIKV) is an emerging virus associated with the Flaviviridae family that mainly causes infection in pregnant women and leads to several abnormalities during pregnancy. This virus has unique properties that may lead to pathological diseases. As the virus has the ability to evade immune response, a crucial effort is required to deal with ZIKV. Vaccines are a safe means to control different pathogenic infectious diseases. In the current research, a multi-epitope-based vaccination against ZIKV is being designed using in silico methods. For the epitope prediction and prioritization phase, ZIKV polyprotein (YP_002790881.1) and flavivirus polyprotein (>YP_009428568.1) were targeted. The predicted B-cell epitopes were used for MHC-I and MHC-II epitope prediction. Afterward, several immunoinformatics filters were applied and nine (REDLWCGSL, MQDLWLLRR, YKKSGITEV, TYTDRRWCF, RDAFPDSNS, KPSLGLINR, ELIGRARVS, AITQGKREE, and EARRSRRAV) epitopes were found to be probably antigenic in nature, non-allergenic, non-toxic, and water soluble without any toxins. Selected epitopes were joined using a particular GPGPG linker to create the base vaccination for epitopes, and an extra EAAAK linker was used to link the adjuvant. A total of 312 amino acids with a molecular weight (MW) of 31.62762 and an instability value of 34.06 were computed in the physicochemical characteristic analysis, indicating that the vaccine design is stable. The molecular docking analysis predicted a binding energy of -329.46 (kcal/mol) for TLR-3 and -358.54 (kcal/mol) for TLR-2. Moreover, the molecular dynamics simulation analysis predicted that the vaccine and receptor molecules have stable binding interactions in a dynamic environment. The C-immune simulation analysis predicted that the vaccine has the ability to generate both humoral and cellular immune responses. Based on the design, the vaccine construct has the best efficacy to evoke immune response in theory, but experimental analysis is required to validate the in silico base approach and ensure its safety.

Commonly Reported Mosquito-Borne Viruses in the United States: A Primer for Pharmacists

Mosquito-borne diseases are a public health concern. Pharmacists are often a patient's first stop for health information and may be asked questions regarding transmission, symptoms, and treatment of mosquito borne viruses (MBVs). The objective of this paper is to review transmission, geographic location, symptoms, diagnosis and treatment of MBVs. We discuss the following viruses with cases in the US in recent years: Dengue, West Nile, Chikungunya, LaCrosse Encephalitis, Eastern Equine Encephalitis Virus, and Zika. Prevention, including vaccines, and the impact of climate change are also discussed.

Dengue Virus and Zika Virus Seroprevalence in the South Pacific Populations of the Cook Islands and Vanuatu

Arboviral diseases are serious threats to global health with increasing prevalence and potentially severe complications. Significant arthropod-borne viruses are the dengue viruses (DENV 1-4), the Zika virus (ZIKV), and the chikungunya virus (CHIKV). Among the areas most affected is the South Pacific Region (SPR). Here, arboviruses not only cause a high local burden of disease, but the region has also proven to contribute to their global spread. Outpatient serum samples collected between 08/2016 and 04/2017 on three islands of the island states of Vanuatu and the Cook Islands were tested for anti-DENV- and anti-ZIKV-specific antibodies (IgG) using enzyme-linked immunosorbent assays (ELISA). ELISA test results showed 89% of all test sera from the Cook Islands and 85% of the Vanuatu samples to be positive for anti-DENV-specific antibodies. Anti-ZIKV antibodies were identified in 66% and 52%, respectively, of the test populations. Statistically significant differences in standardized immunity levels were found only at the intranational level. Our results show that in both the Cook Islands and Vanuatu, residents were exposed to significant Flavivirus transmission. Compared to other seroprevalence studies, the marked difference between ZIKV immunity levels and previously published CHIKV seroprevalence rates in our study populations is surprising. We propose the timing of ZIKV and CHIKV emergence in relation to recurrent DENV outbreaks and the impact of seasonality as explanatory external factors for this observation. Our data add to the knowledge of arboviral epidemics in the SPR and contribute to a better understanding of virus spread, including external conditions with potential influence on outbreak dynamics. These data may support preventive and rapid response measures in the affected areas, travel-related risk assessment, and infection identification in locals and returning travelers.

Evaluation of clinical and laboratory characteristics of dengue viral infection and risk factors of dengue hemorrhagic fever: a multi-center retrospective analysis

BACKGROUND

Dengue Viral Infection (DVI) has become endemic in Pakistan since the first major outbreak in Karachi in 1996. Despite aggressive measures taken by relevant authorities, Pakistan has been dealing with a worsening dengue crisis for the past two decades. DHF is severe form of dengue infection which is linked with significant morbidity and mortality. Early identification of severe dengue infections can reduce the morbidity and mortality. In this context we planned current study in which we find out the different factors related with DHF as well as clinical laboratory features of DHF and compare them to DF so that patients can be best evaluated for DHF and managed accordingly at admission.

METHODS

Retrospective study conducted over a period of 6 years (2013-2018) in two tertiary care hospitals in Pakistan. Data were collected by using a pre-structured data collection form. Data were statistically analyzed to determine the clinical and laboratory characteristics of DVI and risk factors of dengue hemorrhagic fever (DHF).

RESULTS

A total 512 dengue cases (34.05 ± 15.08 years; Male 69.53%) were reviewed. Most common clinical manifestations of DVI were fever (99.60%), headache (89.1%), chills (86.5%), rigors (86.5%), myalgia (72.3%). Less common clinical manifestations were vomiting (52.5%), arthralgia (50.2%) and skin rashes (47.5%). Furthermore, nasal bleeding (44.1%), gum bleeding (32.6%), pleural effusion (13.9%) and hematuria (13.1%) were more profound clinical presentations among DHF patients. Mortality rate was 1.5% in this study. Logistic regression analysis indicated that delayed hospitalization (OR: 2.30) and diabetes mellitus (OR:2.71), shortness of breath (OR:2.21), association with risk groups i.e., living near stagnant water, travelling to endemic areas, living in endemic regions (OR:1.95), and presence of warning signs (OR:2.18) were identified as risk factors of DHF. Statistically we found that there is strong association of diabetes mellitus (DM) with DHF while the patient suffering from DM individually had higher odds (2.71) of developing DHF than patients without disease.

CONCLUSIONS

The current study demonstrated that the clinical and laboratory profiles of DF and DHF are significantly distinct. Significant predictors of DHF were advanced age, diabetes mellitus, ascites, pleural effusion, thick gallbladder and delayed hospitalization. The identification of these factors at early stage provides opportunities for the clinicians to identify high risk patients and to reduce dengue-related morbidity and mortality.

The potential habitat and environmental fitness change of Aedes albopictus in Western Eurasia for 2081-2100

BACKGROUND OBJECTIVES

The range of Aedes albopictus, the most important vector mosquito in Western Eurasia is growing due to climate change. However, it is not known how it will influence the habitats occupied by the species and its environmental fitness within its future range.

METHODS

To study this question, the habitat characteristic of the mosquito was investigated for 2081-2100.

RESULTS

The models suggest a notable future spread of the mosquito in the direction of Northern Europe and the parallel northward and westward shift of the southern and eastern potential occurrences of the mosquito. The models suggest a notable increase in generation numbers in the warmest quarter, which can reach 4-5 generations in the peri-Mediterranean region. However, both the joint survival rate of larvae and pupae and the number of survival days of adults in the warmest quarter exhibit decreasing values, as does the potential disappearance of the mosquito in the southern regions of Europe and Asia Minor, along with the growing atmospheric CO2 concentration-based scenarios.

INTERPRETATION CONCLUSION

While in 1970-2000 Aedes albopictus mainly occupied the hot and warm summer temperate regions of Europe, the species will inhabit dominantly the cool summer temperate (oceanic) and the humid continental climate territories of North and North-Eastern Europe in 2081-2100.

Has Zika been forgotten? A qualitative exploration of knowledge gaps, perceived risk and preventive practices in pregnant women in Malaysia

BACKGROUND

Although Zika virus infection is rarely reported now, continuous prevention is needed to achieve sustained eradication. This study aimed to explore the knowledge gaps, risk perception and preventive measures against Zika virus infection (ZIKV) in pregnant women in Malaysia.

METHODS

We conducted in-depth virtual interviews with pregnant women between February and April 2022. The interviews were recorded and transcribed, and data were analyzed by content analysis.

RESULTS

The majority of the participants demonstrated a commendable level of awareness regarding the signs and symptoms associated with ZIKV infection. They also exhibited a clear understanding of preventive measures, particularly emphasizing the importance of avoiding mosquito bites to minimize the risk of ZIKV transmission. However, a noteworthy gap in knowledge surfaced as a subset of participants remained uninformed about the potential for sexual transmission of ZIKV, which could lead to congenital ZIKV in pregnant women. Even among women who were cognizant of ZIKV and its potential negative health outcomes, associated with the infection, many of them did not perceive themselves to be at risk, mainly because ZIKV infection is infrequently discussed or heard of, leading to a sense of infections' rarity. While the adoption of preventive measures such as mosquito bite prevention during pregnancy was a common practice, however, prevention of sexually transmitted infections (STIs) including mosquito-borne diseases such as Zika is low. A minority of women express concerns about the sensitivity surrounding discussions and prevention of STIs within the context of marriage. Most of the participants were supportive of the provision of awareness of ZIKV infection in women during pregnancy and the involvement of men, especially in initiatives aimed at preventing transmission through sexual contact.

CONCLUSION

This study uncovered gaps in both knowledge and practices pertaining ZIKV infection among pregnant women in the aftermath of the ZIKV pandemic. The insights gleaned from our research are valuable for shaping future interventions geared towards preventing the resurgence or facilitating the sustainable eradication of ZIKV.

Roles of NS1 Protein in Flavivirus Pathogenesis

Flaviviruses such as dengue, Zika, and West Nile viruses are highly concerning pathogens that pose significant risks to public health. The NS1 protein is conserved among flaviviruses and is synthesized as a part of the flavivirus polyprotein. It plays a critical role in viral replication, disease progression, and immune evasion. Post-translational modifications influence NS1's stability, secretion, antigenicity, and interactions with host factors. NS1 protein forms extensive interactions with host cellular proteins allowing it to affect vital processes such as RNA processing, gene expression regulation, and cellular homeostasis, which in turn influence viral replication, disease pathogenesis, and immune responses. NS1 acts as an immune evasion factor by delaying complement-dependent lysis of infected cells and contributes to disease pathogenesis by inducing endothelial cell damage and vascular leakage and triggering autoimmune responses. Anti-NS1 antibodies have been shown to cross-react with host endothelial cells and platelets, causing autoimmune destruction that is hypothesized to contribute to disease pathogenesis. However, in contrast, immunization of animal models with the NS1 protein confers protection against lethal challenges from flaviviruses such as dengue and Zika viruses. Understanding the multifaceted roles of NS1 in flavivirus pathogenesis is crucial for effective disease management and control. Therefore, further research into NS1 biology, including its host protein interactions and additional roles in disease pathology, is imperative for the development of strategies and therapeutics to combat flavivirus infections successfully. This Review provides an in-depth exploration of the current available knowledge on the multifaceted roles of the NS1 protein in the pathogenesis of flaviviruses.

Antibody and Cell-Based Therapies against Virus-Induced Cancers in the Context of HIV/AIDS

Infectious agents, notably viruses, can cause or increase the risk of cancer occurrences. These agents often disrupt normal cellular functions, promote uncontrolled proliferation and growth, and trigger chronic inflammation, leading to cancer. Approximately 20% of all cancer cases in humans are associated with an infectious pathogen. The International Agency for Research on Cancer (IARC) recognizes seven viruses as direct oncogenic agents, including Epstein-Barr Virus (EBV), Kaposi's Sarcoma-associated herpesvirus (KSHV), human T-cell leukemia virus type-1 (HTLV-1), human papilloma virus (HPV), hepatitis C virus (HCV), hepatitis B virus (HBV), and human immunodeficiency virus type 1 (HIV-1). Most viruses linked to increased cancer risk are typically transmitted through contact with contaminated body fluids and high-risk behaviors. The risk of infection can be reduced through vaccinations and routine testing, as well as recognizing and addressing risky behaviors and staying informed about public health concerns. Numerous strategies are currently in pre-clinical phases or undergoing clinical trials for targeting cancers driven by viral infections. Herein, we provide an overview of risk factors associated with increased cancer incidence in people living with HIV (PLWH) as well as other chronic viral infections, and contributing factors such as aging, toxicity from ART, coinfections, and comorbidities. Furthermore, we highlight both antibody- and cell-based strategies directed against virus-induced cancers while also emphasizing approaches aimed at discovering cures or achieving complete remission for affected individuals.

Genome-wide detection of Wolbachia in natural Aedes aegypti populations using ddRAD-Seq

Background

Wolbachia, an endosymbiotic bacterium, is globally used to control arboviruses because of its ability to block arboviral replication and manipulate the reproduction of Wolbachia host, Aedes aegypti. Polymerase chain reaction (PCR)-based Wolbachia detection has been recently reported from natural Ae. aegypti populations. However, due to the technical limitations of PCR, such as primer incompatibility, PCR-based assays are not sufficiently reliable or accurate. In this study, we examined double digestion restriction site-associated DNA sequencing (ddRAD-Seq) efficiency and limitations in Wolbachia detection and quantification in field-collected Ae. aegypti natural populations in Metro Manila, the Philippines, compared with PCR-based assays.

Methods

A total of 217 individuals Ae. aegypti were collected from Metropolitan Manila, Philippines. We separated it into 14 populations consisting of 7 female and male populations. We constructed a library for pool ddRAD-Seq per population and also screened for Wolbachia by PCR assays using wsp and 16S rRNA. Wolbachia density per population were measured using RPS17 as the housekeeping gene.

Results

From 146,239,637 sequence reads obtained, 26,299 and 43,778 reads were mapped across the entire Wolbachia genome (with the wAlbA and wAlbB strains, respectively), suggesting that ddRAD-Seq complements PCR assays and supports more reliable Wolbachia detection from a genome-wide perspective. The number of reads mapped to the Wolbachia genome per population positively correlated with the number of Wolbachia-infected individuals per population based on PCR assays and the relative density of Wolbachia in the Ae. aegypti populations based on qPCR, suggesting ddRAD-Seq-based semi-quantification of Wolbachia by ddRAD-Seq. Male Ae. aegypti exhibited more reads mapped to the Wolbachia genome than females, suggesting higher Wolbachia prevalence rates in their case. We detected 150 single nucleotide polymorphism loci across the Wolbachia genome, allowing for more accurate the detection of four strains: wPip, wRi, TRS of Brugia malayi, and wMel.

Conclusions

Taken together, our results demonstrate the feasibility of ddRAD-Seq-based Wolbachia detection from field-collected Ae. aegypti mosquitoes.

Spatial model of Dengue Hemorrhagic Fever (DHF) risk: scoping review

BACKGROUND

Creating a spatial model of dengue fever risk is challenging duet to many interrelated factors that could affect dengue. Therefore, it is crucial to understand how these critical factors interact and to create reliable predictive models that can be used to mitigate and control the spread of dengue.

METHODS

This scoping review aims to provide a comprehensive overview of the important predictors, and spatial modelling tools capable of producing Dengue Haemorrhagic Fever (DHF) risk maps. We conducted a methodical exploration utilizing diverse sources, i.e., PubMed, Scopus, Science Direct, and Google Scholar. The following data were extracted from articles published between January 2011 to August 2022: country, region, administrative level, type of scale, spatial model, dengue data use, and categories of predictors. Applying the eligibility criteria, 45 out of 1,349 articles were selected.

RESULTS

A variety of models and techniques were used to identify DHF risk areas with an arrangement of various multiple-criteria decision-making, statistical, and machine learning technique. We found that there was no pattern of predictor use associated with particular approaches. Instead, a wide range of predictors was used to create the DHF risk maps. These predictors may include climatology factors (e.g., temperature, rainfall, humidity), epidemiological factors (population, demographics, socio-economic, previous DHF cases), environmental factors (land-use, elevation), and relevant factors.

CONCLUSIONS

DHF risk spatial models are useful tools for detecting high-risk locations and driving proactive public health initiatives. Relying on geographical and environmental elements, these models ignored the impact of human behaviour and social dynamics. To improve the prediction accuracy, there is a need for a more comprehensive approach to understand DHF transmission dynamics.

Effects of different diets on Aedes aegypti adults: improving rearing techniques for sterile insect technique

The aim was to evaluate the effect of different energy diets available in adulthood on the longevity, dispersal capacity and sexual performance of Aedes aegypti produced under a mass-rearing system. To evaluate the effects of diets in relation to the survival of the adult male insects of Ae. aegypti, six treatments were used: sucrose at a concentration of 10%, as a positive control (sack10); starvation, as a negative control (starvation); sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid (sac20vitC); wild honey in a concentration of 10% (honey10); demerara sugar in a 10% concentration (demerara10); and sucrose at a concentration of 20% associated with 1 g/l of ascorbic acid and 0.5 g/l of amino acid proline (sac20vitCPr). Each treatment had 16 cages containing 50 adult males. For the tests of flight ability and propensity to copulation, five treatments were used (saca10; sac20vitC; mel10; demerara10; and sac20vitCPr), with males each for flight ability and females copulated by a single male for copulation propensity. The diet composed of sucrose at a concentration of 20% associated with ascorbic acid, as an antioxidant, improved the survival, flight ability and propensity to copulate in Ae. aegypti males under mass-rearing conditions, and may be useful to enhance the performance of sterile males, thus improving the success of sterile insect technique programmes.

The Innate Immune Response in DENV- and CHIKV-Infected Placentas and the Consequences for the Fetuses: A Minireview

Dengue virus (DENV) and chikungunya (CHIKV) are arthropod-borne viruses belonging to the Flaviviridae and Togaviridae families, respectively. Infection by both viruses can lead to a mild indistinct fever or even lead to more severe forms of the diseases, which are characterized by a generalized inflammatory state and multiorgan involvement. Infected mothers are considered a high-risk group due to their immunosuppressed state and the possibility of vertical transmission. Thereby, infection by arboviruses during pregnancy portrays a major public health concern, especially in countries where epidemics of both diseases are regular and public health policies are left aside. Placental involvement during both infections has been already described and the presence of either DENV or CHIKV has been observed in constituent cells of the placenta. In spite of that, there is little knowledge regarding the intrinsic earlier immunological mechanisms that are developed by placental cells in response to infection by both arboviruses. Here, we approach some of the current information available in the literature about the exacerbated presence of cells involved in the innate immune defense of the placenta during DENV and CHIKV infections.

Multifaceted Nature of Lipid Droplets in Viral Interactions and Pathogenesis

Once regarded as inert organelles with limited and ill-defined roles, lipid droplets (LDs) have emerged as dynamic entities with multifaceted functions within the cell. Recent research has illuminated their pivotal role as primary energy reservoirs in the form of lipids, capable of being metabolized to meet cellular energy demands. Their high dynamism is underscored by their ability to interact with numerous cellular organelles, notably the endoplasmic reticulum (the site of LD genesis) and mitochondria, which utilize small LDs for energy production. Beyond their contribution to cellular bioenergetics, LDs have been associated with viral infections. Evidence suggests that viruses can co-opt LDs to facilitate their infection cycle. Furthermore, recent discoveries highlight the role of LDs in modulating the host's immune response. Observations of altered LD levels during viral infections suggest their involvement in disease pathophysiology, potentially through production of proinflammatory mediators using LD lipids as precursors. This review explores these intriguing aspects of LDs, shedding light on their multifaceted nature and implications in viral interactions and disease development.

Mosquito Larvicidal Activity and Cytotoxicity of the Extracts of Aromatic Plants from Malaysia

Despite ongoing control efforts, the mosquito population and diseases vectored by them continue to thrive worldwide, causing major health concerns. There has been growing interest in the use of botanicals as alternatives to insecticides due to their widespread insecticidal properties, biodegradability, and adaptability to ecological conditions. In this study, we investigated the larvicidal activity and cytotoxicity effects of solvent extracts from three aromatic plants-Curcuma longa (turmeric), Ocimum americanum (hoary basil), and Petroselinum crispum (parsley)-against Aedes albopictus. Subsequently, we examined the phytochemical composition of the extracts through gas chromatography-mass spectrometry (GC-MS) analysis. Results revealed that the hexane extracts of O. americanum and P. crispum exhibited the greatest larvicidal activity with the lowest median lethal concentration (LC₅₀) values (<30 µg/mL) at 24 h post-treatment, with the former found to be significantly less toxic towards African monkey kidney (Vero) cells. The GC-MS analysis of the said extract indicated the presence of different classes of metabolites, including phenylpropanoids, very long-chain alkanes, fatty acids and their derivatives, and terpenes, with the most abundant component being methyl eugenol (55.28%), most of which, have been documented for their larvicidal activities. These findings provide valuable insights into the potential use and development of bioinsecticides, particularly from O. americanum.

Dengue Virus Capsid Protein Facilitates Genome Compaction and Packaging

Dengue virus (DENV) is a single-stranded (+)-sense RNA virus that infects humans and mosquitoes, posing a significant health risk in tropical and subtropical regions. Mature virions are composed of an icosahedral shell of envelope (E) and membrane (M) proteins circumscribing a lipid bilayer, which in turn contains a complex of the approximately 11 kb genomic RNA with capsid (C) proteins. Whereas the structure of the envelope is clearly defined, the structure of the packaged genome in complex with C proteins remains elusive. Here, we investigated the interactions of C proteins with viral RNA, in solution and inside mature virions, via footprinting and cross-linking experiments. We demonstrated that C protein interaction with DENV genomes saturates at an RNA:C protein ratio below 1:250. Moreover, we also showed that the length of the RNA genome interaction sites varies, in a multimodal distribution, consistent with the C protein binding to each RNA site mostly in singlets or pairs (and, in some instances, higher numbers). We showed that interaction sites are preferentially sites with low base pairing, as previously measured by 2'-acetylation analyzed by primer extension (SHAPE) reactivity indicating structuredness. We found a clear association pattern emerged: RNA-C protein binding sites are strongly associated with long-range RNA-RNA interaction sites, particularly inside virions. This, in turn, explains the need for C protein in viral genome packaging: the protein has a chief role in coordinating these key interactions, promoting proper packaging of viral RNA. Such sites are, thus, highly consequential for viral assembly, and, as such, may be targeted in future drug development strategies against these and related viruses.

Dengue as a Disease Threatening Global Health: A Narrative Review Focusing on Latin America and Brazil

Arboviruses constitute the largest known group of viruses. These viruses are the etiological agents of pathologies known as arboviruses, with dengue being one of the most prevalent. Dengue has resulted in important socioeconomic burdens placed on different countries around the world, including those in Latin America, especially Brazil. Thus, this work intends to carry out a narrative-based review of the literature, conducted using a study of the secondary data developed through a survey of scientific literature databases, and to present the situation of dengue, particularly its distribution in these localities. Our findings from the literature demonstrate the difficulties that managers face in controlling the spread of and planning a response against dengue, pointing to the high cost of the disease for public coffers, rendering the resources that are already limited even scarcer. This can be associated with the different factors that affect the spread of the disease, including ecological, environmental, and social factors. Thus, in order to combat the disease, it is expected that targeted and properly coordinated public policies need to be adopted not only in specific localities, but also globally.

The Importance of Epigallocatechin as a Scaffold for Drug Development against Flaviviruses

Arboviruses such as Dengue, yellow fever, West Nile, and Zika are flaviviruses vector-borne RNA viruses transmitted biologically among vertebrate hosts by blood-taking vectors. Many flaviviruses are associated with neurological, viscerotropic, and hemorrhagic diseases, posing significant health and socioeconomic concerns as they adapt to new environments. Licensed drugs against them are currently unavailable, so searching for effective antiviral molecules is still necessary. Epigallocatechin molecules, a green tea polyphenol, have shown great virucidal potential against flaviviruses, including DENV, WNV, and ZIKV. The interaction of EGCG with the viral envelope protein and viral protease, mainly identified by computational studies, describes the interaction of these molecules with viral proteins; however, how the viral NS2B/NS3 protease interacts with epigallocatechin molecules is not yet fully deciphered. Consequently, we tested the antiviral potential of two epigallocatechin molecules (EGC and EGCG) and their derivative (AcEGCG) against DENV, YFV, WNV, and ZIKV NS2B/NS3 protease. Thus, we assayed the effect of the molecules and found that a mixture of the molecules EGC (competitive) and EGCG (noncompetitive) inhibited the virus protease of YFV, WNV, and ZIKV more effectively with IC50 values of 1.17 ± 0.2 µM, 0.58 ± 0.07 µM, and 0.57 ± 0.05 µM, respectively. As these molecules fundamentally differ in their inhibitory mode and chemical structure, our finding may open a new line for developing more effective allosteric/active site inhibitors to combat flaviviruses infection.

Chemical Composition, Larvicidal and Repellent Activities of Wild Plant Essential Oils against Aedes aegypti

Bio-degradable and eco-friendly essential oils (EOs) extracted from Mentha longifolia, Salsola imbricata, Erigeron bonariensis, E. canadensis, Ailanthus altissima, and Zanthoxylum armatum were investigated for their repellent and larvicidal potential against Aedes aegypti mosquitoes. The EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis, A. altissima, and Z. armatum exhibited 99.0%, 96.8%, 40.2%, 41.7%, 29.1%, and 13.2% repellency against mosquitoes at a tested dose of 33.3 μg/cm², respectively. In time span bioassays, the EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis showed more than 40% repellency for 60 min at a tested dose of 330 μg/cm². Larvicidal bioassays revealed that larvae of Ae. aegypti were the most susceptible to M. longifolia (LC₅₀, 39.3 mg/L), E. bonariensis (LC₅₀, 26.0 mg/L), E. canadensis (LC₅₀, 35.7 mg/L), and Z. armatum (LC₅₀, 35.9 mg/L) EOs upon 48 h exposure. The most abundant constituents in the EOs of M. longifolia, S. imbricata, E. bonariensis, E. canadensis and A. altissima were piperitone oxide (45.5%), carvone (39.9%), matricaria ester (43.1%), (31.7%) and eugenol (24.4%), respectively. Our study demonstrates that EOs of M. longifolia, S. imbricata, E. bonariensis, and E. canadensis might be used to control Ae. aegypti mosquitoes without harming humans or the environment.

Inhibitory Potential of Chromene Derivatives on Structural and Non-Structural Proteins of Dengue Virus

Dengue fever is a mosquito-borne viral disease that has become a serious health issue across the globe. It is caused by a virus of the Flaviviridae family, and it comprises five different serotypes (DENV-1 to DENV-5). As there is no specific medicine or effective vaccine for controlling dengue fever, there is an urgent need to develop potential inhibitors against it. Traditionally, various natural products have been used to manage dengue fever and its co-morbid conditions. A detailed analysis of these plants revealed the presence of various chromene derivatives as the major phytochemicals. Inspired by these observations, authors have critically analyzed the anti-dengue virus potential of various 4H chromene derivatives. Further, in silico, in vitro, and in vivo reports of these scaffolds against the dengue virus are detailed in the present manuscript. These analogues exerted their activity by interfering with various stages of viral entry, assembly, and replications. Moreover, these analogues mainly target envelope protein, NS2B-NS3 protease, and NS5 RNA-dependent RNA polymerase, etc. Overall, chromene-containing analogues exerted a potent activity against the dengue virus and the present review will be helpful for the further exploration of these scaffolds for the development of novel antiviral drug candidates.

Dengue, West Nile, and Zika Viruses: Potential Novel Antiviral Biologics Drugs Currently at Discovery and Preclinical Development Stages

Dengue, West Nile and Zika viruses are vector-borne flaviviruses responsible for numerous disease outbreaks in both Hemispheres. Despite relatively low mortality, infection may lead to potentially severe situations such as (depending on the virus): hypovolemic shock, encephalitis, acute flaccid paralysis, Guillain-Barré syndrome, congenital malformations (e.g., microcephaly) and, in some situations, death. Moreover, outbreaks also have major socioeconomic repercussions, especially in already vulnerable societies. Thus far, only generic symptoms relief is possible, as there are no specific treatments available yet. Dengvaxia was the world's first dengue vaccine. However, it is not fully effective. Prophylactic approaches against West Nile and Zika viruses are even more limited. Therefore, therapeutic strategies are required and will be discussed hereafter. We will first briefly present these viruses' epidemiology, life cycle and structure. Then, we introduce the clinical presentation, diagnosis approaches and available vaccines. Finally, we list and discuss promising compounds at discovery and preclinical development stages already deposited at the GlobalData database and divided into three main types, according to therapeutic molecule: antibody-based, peptide-based molecules and, other compounds. To conclude, we discuss and compare promising developments, useful for future therapies against these three flaviviruses of major concern to human health.

Advances in Computational Methods to Discover New NS2B-NS3 Inhibitors Useful Against Dengue and Zika Viruses

The Flaviviridae virus family consists of the genera Hepacivirus, Pestivirus, and Flavivirus, with approximately 70 viral types that use arthropods as vectors. Among these diseases, dengue (DENV) and zika virus (ZIKV) serotypes stand out, responsible for thousands of deaths worldwide. Due to the significant increase in cases, the World Health Organization (WHO) declared DENV a potential threat for 2019 due to being transmitted by infected travelers. Furthermore, ZIKV also has a high rate of transmissibility, highlighted in the outbreak in 2015, generating consequences such as Guillain-Barré syndrome and microcephaly. According to clinical outcomes, those infected with DENV can be asymptomatic, and in other cases, it can be lethal. On the other hand, ZIKV has severe neurological symptoms in newborn babies and adults. More serious symptoms include microcephaly, brain calcifications, intrauterine growth restriction, and fetal death. Despite these worrying data, no drug or vaccine is approved to treat these diseases. In the drug discovery process, one of the targets explored against these diseases is the NS2B-NS3 complex, which presents the catalytic triad His51, Asp75, and Ser135, with the function of cleaving polyproteins, with specificity for basic amino acid residues, Lys- Arg, Arg-Arg, Arg-Lys or Gln-Arg. Since NS3 is highly conserved in all DENV serotypes and plays a vital role in viral replication, this complex is an excellent drug target. In recent years, computer-aided drug discovery (CADD) is increasingly essential in drug discovery campaigns, making the process faster and more cost-effective, mainly explained by discovering new drugs against DENV and ZIKV. Finally, the main advances in computational methods applied to discover new compounds against these diseases will be presented here. In fact, molecular dynamics simulations and virtual screening is the most explored approach, providing several hit and lead compounds that can be used in further optimizations. In addition, fragment-based drug design and quantum chemistry/molecular mechanics (QM/MM) provides new insights for developing anti-DENV/ZIKV drugs. We hope that this review offers further helpful information for researchers worldwide and stimulates the use of computational methods to find a promising drug for treating DENV and ZIKV.

Isoquercetin as an Anti-Covid-19 Medication: A Potential to Realize

Isoquercetin and quercetin are secondary metabolites found in a variety of plants, including edible ones. Isoquercetin is a monoglycosylated derivative of quercetin. When ingested, isoquercetin accumulates more than quercetin in the intestinal mucosa where it is converted to quercetin; the latter is absorbed into enterocytes, transported to the liver, released in circulation, and distributed to tissues, mostly as metabolic conjugates. Physiologically, isoquercetin and quercetin exhibit antioxidant, anti-inflammatory, immuno-modulatory, and anticoagulant activities. Generally isoquercetin is less active than quercetin in vitro and ex vivo, whereas it is equally or more active in vivo, suggesting that it is primarily a more absorbable precursor to quercetin, providing more favorable pharmacokinetics to the latter. Isoquercetin, like quercetin, has shown broad-spectrum antiviral activities, significantly reducing cell infection by influenza, Zika, Ebola, dengue viruses among others. This ability, together with their other physiological properties and their safety profile, has led to the proposition that administration of these flavonols could prevent infection by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), or arrest the progression to severity and lethality of resulting coronavirus disease of 2019 (Covid-19). In silico screening of small molecules for binding affinity to proteins involved SARS-CoV-2 life cycle has repeatedly situated quercetin and isoquercetin near to top of the list of likely effectors. If experiments in cells and animals confirm these predictions, this will provide additional justifications for the conduct of clinical trials to evaluate the prophylactic and therapeutic efficacy of these flavonols in Covid-19.

Traditional Knowledge to Contemporary Medication in the Treatment of Infectious Disease Dengue: A Review

Dengue has become a worldwide affliction despite incessant efforts to search for a cure for this long-lived disease. Optimistic consequences for dengue vaccine are implausible as the efficiency is tied to previous dengue virus (DENV) exposure and a very high cost is required for large-scale production of vaccine. Medicinal plants are idyllic substitutes to fight DENV infection since they constitute important components of traditional medicine and show antiviral properties, although the mechanism behind the action of bioactive compounds to obstruct viral replication is less explored and yet to be discovered. This review includes the existing traditional knowledge on how DENV infects and multiplies in the host cells, conscripting different medicinal plants that obtained bioactive compounds with anti-dengue properties, and the probable mechanism on how bioactive compounds modulate the host immune system during DENV infection. Moreover, different plant species having such bioactive compounds reported for anti-DENV efficiency should be validated scientifically via different in vitro and in vivo studies.

Oviposition dynamics of Aedes aegypti in Central Argentina

Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) is the vector of multiple arboviruses. To evaluate the association between environmental factors and the oviposition activity of Ae. aegypti in Argentina, data on the presence and abundance of eggs were collected using ovitraps, between September of 2018 and May of 2019, in the cities of Villa María, Río Cuarto and Salsipuedes (Córdoba province, Argentina). We analysed the relationships between oviposition and five environmental factors: Temperature, precipitation, vegetation cover, human population density and distance to sites with a potential high density of larval habitats, like cemeteries and trash dumps. Environmental factors' data were collected using satellite image products. The oviposition activity was randomly distributed in three cities. Using generalized linear mixed models, we show that the house where each ovitrap was placed was a source of variability in oviposition, suggesting the relevance of microsite factors and the importance of domestic control actions. Ae. aegypti oviposition was positively correlated with night-time temperature of the previous 3 weeks, and in a context-dependent manner, it was positively correlated with human population density, vegetation cover and precipitation. The consistency and magnitude of these relationships varied between cities, indicating that oviposition is related to a complex system of environmental variables.

Optimization of 4-Anilinoquinolines as Dengue Virus Inhibitors

Emerging viral infections, including those caused by dengue virus (DENV) and Venezuelan Equine Encephalitis virus (VEEV), pose a significant global health challenge. Here, we report the preparation and screening of a series of 4-anilinoquinoline libraries targeting DENV and VEEV. This effort generated a series of lead compounds, each occupying a distinct chemical space, including 3-((6-bromoquinolin-4-yl)amino)phenol (12), 6-bromo-N-(5-fluoro-1H-indazol-6-yl)quinolin-4-amine (50) and 6-((6-bromoquinolin-4-yl)amino)isoindolin-1-one (52), with EC₅₀ values of 0.63–0.69 µM for DENV infection. These compound libraries demonstrated very limited toxicity with CC₅₀ values greater than 10 µM in almost all cases. Additionally, the lead compounds were screened for activity against VEEV and demonstrated activity in the low single-digit micromolar range, with 50 and 52 demonstrating EC₅₀s of 2.3 µM and 3.6 µM, respectively. The promising results presented here highlight the potential to further refine this series in order to develop a clinical compound against DENV, VEEV, and potentially other emerging viral threats.

SARS-CoV-2, Zika viruses and mycoplasma: Structure, pathogenesis and some treatment options in these emerging viral and bacterial infectious diseases

The molecular evolution of life on earth along with changing environmental, conditions has rendered mankind susceptible to endemic and pandemic emerging infectious diseases. The effects of certain systemic viral and bacterial infections on morbidity and mortality are considered as examples of recent emerging infections. Here we will focus on three examples of infections that are important in pregnancy and early childhood: SARS-CoV-2 virus, Zika virus, and Mycoplasma species. The basic structural characteristics of these infectious agents will be examined, along with their general pathogenic mechanisms. Coronavirus infections, such as caused by the SARS-CoV-2 virus, likely evolved from zoonotic bat viruses to infect humans and cause a pandemic that has been the biggest challenge for humanity since the Spanish Flu pandemic of the early 20th century. In contrast, Zika Virus infections represent an expanding infectious threat in the context of global climate change. The relationship of these infections to pregnancy, the vertical transmission and neurological sequels make these viruses highly relevant to the topics of this special issue. Finally, mycoplasmal infections have been present before mankind evolved, but they were rarely identified as human pathogens until recently, and they are now recognized as important coinfections that are able to modify the course and prognosis of various infectious diseases and other chronic illnesses. The infectious processes caused by these intracellular microorganisms are examined as well as some general aspects of their pathogeneses, clinical presentations, and diagnoses. We will finally consider examples of treatments that have been used to reduce morbidity and mortality of these infections and discuss briefly the current status of vaccines, in particular, against the SARS-CoV-2 virus. It is important to understand some of the basic features of these emerging infectious diseases and the pathogens involved in order to better appreciate the contributions of this special issue on how infectious diseases can affect human pregnancy, fetuses and neonates.

Seroprevalence of Zika virus in pregnant women from central Thailand

Zika virus (ZKV) infection in a pregnant woman, especially during the first trimester, often results in congenital anomalies. However, the pathogenic mechanism is unknown and one-third of ZKV infected pregnancies are asymptomatic. Neutralizing antibodies against ZKV has been reported in 70% of Thai adults, but the prevalence among pregnant women is unknown. Currently, vaccines and specific treatments for ZKV are under development. A better understanding of the immune status of pregnant women will increase the success of effective prevention guidelines. The prevalence of ZKV infection in pregnant women in antenatal care clinics was investigated during the rainy season from May to October 2019 at Siriraj Hospital, Bangkok, Thailand. We recruited 650 pregnant women (39.42% first, 52.26% second and 7.36% third trimester) and found that 30.77% had ZKV-specific IgG, and 39.81% had neutralizing antibodies (nAb) against ZKV (titer ≥10). Specific and neutralizing antibody levels varied by maternal age, trimester, and month. We further characterized the cross-reaction between ZKV and the four Dengue virus (DENV) serotypes by focused reduction neutralization test (FRNT) and found that cross-reactions were common. In conclusion, about 60% of pregnant women who living in central Thailand may be at risk of ZKV infection due to the absence of neutralizing antibodies against ZKV. The functions of cross-reactive antibodies between related viral genotypes require further study. These findings have implications for health care monitoring in pregnant women including determining the risk of ZKV infection, assisting the development of a flavivirus vaccine, and informing the development of preventative health policies.

Overview of Pathogenesis, Diagnostics, and Therapeutics of Infectious Diseases: Dengue and Zika

The emergence of more virulent SARS virus has made scientists look back at other so-called neglected diseases such as dengue, Zika, and chikungunya, etc. Until recently these neglected diseases have not received much attention for their control or elimination from society. Over the past decade several attempts to investigate the pathogenicity, diagnostic, and therapeutic strategies for flavivirus caused diseases have been made. Herein we have reviewed the progress made toward the detection and treatment of two diseases-dengue and Zika. The above flavivirus related pathogenesis is concerned with the host immune system and known to be mediated through various receptors along with antibody-mediated disease enhancement. Moreover, researchers have been progressing toward discovering new drugs and therapeutic methods that target various stages of the flavivirus life cycle to minimize the above caused mortality and morbidity. The available diagnostics are based on serological, small molecule detection systems and point-of-care sensing devices. In this work, we have reviewed the advancements made toward understanding the pathogenesis, diagnostics, and therapeutics of the viral diseases caused by dengue and Zika.

Viral and Prion Infections Associated with Central Nervous System Syndromes in Brazil

Virus-induced infections of the central nervous system (CNS) are among the most serious problems in public health and can be associated with high rates of morbidity and mortality, mainly in low- and middle-income countries, where these manifestations have been neglected. Typically, herpes simplex virus 1 and 2, varicella-zoster, and enterovirus are responsible for a high number of cases in immunocompetent hosts, whereas other herpesviruses (for example, cytomegalovirus) are the most common in immunocompromised individuals. Arboviruses have also been associated with outbreaks with a high burden of neurological disorders, such as the Zika virus epidemic in Brazil. There is a current lack of understanding in Brazil about the most common viruses involved in CNS infections. In this review, we briefly summarize the most recent studies and findings associated with the CNS, in addition to epidemiological data that provide extensive information on the circulation and diversity of the most common neuro-invasive viruses in Brazil. We also highlight important aspects of the prion-associated diseases. This review provides readers with better knowledge of virus-associated CNS infections. A deeper understanding of these infections will support the improvement of the current surveillance strategies to allow the timely monitoring of the emergence/re-emergence of neurotropic viruses.

Causes of Phenotypic Variability and Disabilities after Prenatal Viral Infections

Prenatal viral infection can lead to a spectrum of neurodevelopmental disabilities or fetal demise. These can include microencephaly, global developmental delay, intellectual disability, refractory epilepsy, deafness, retinal defects, and cortical-visual impairment. Each of these clinical conditions can occur on a semi-quantitative to continuous spectrum, from mild to severe disease, and often as a collective of phenotypes. Such serious outcomes result from viruses’ overlapping neuropathology and hosts’ common neuronal and gene regulatory response to infections. The etiology of variability in clinical outcomes is not yet clear, but it may be related to viral, host, vector, and/or environmental risk and protective factors that likely interact in multiple ways. In this perspective of the literature, we work toward understanding the causes of phenotypic variability after prenatal viral infections by highlighting key aspects of the viral lifecycle that can affect human disease, with special attention to the 2015 Zika pandemic. Therefore, this work offers important insights into how viral infections and environmental teratogens affect the prenatal brain, toward our ultimate goal of preventing neurodevelopmental disabilities.

Differential expression of miRNAs in a human developing neuronal cell line chronically infected with Zika virus

Zika virus (ZIKV) is a serious public health concern that may lead to neurological disorders in affected individuals. The virus can be transmitted from an infected mother to her fetus, via mosquitoes, or sexually. ZIKV infections are associated with increased risk for Guillain-Barré syndrome (GBS) and congenital microcephaly in newborns infected prenatally. Dysregulations of intracellular microRNAs (miRNAs) in infected neurons have been linked to different neurological diseases. To determine the potential role of miRNAs in ZIKV infection we developed a chronically infected neuroblastoma cell line and carried out differential expression analyses of miRNAs with reference to an uninfected neuroblastoma cell line. A total of 3192miRNAs were evaluated and 389 were found to be upregulated < 2-fold and 1291 were downregulated < 2-fold. In particular, we determined that hsa-mir-431-5p, hsa-mir-3687, hsa-mir-4655-5p, hsa-mir-6071, hsa-mir-762, hsa-mir-5787, and hsa-mir-6825-3p were significantly downregulated, ranging from -5711 to -660-fold whereas, has-mir-4315, hsa-mir-5681b, hsa-mir-6511a-3p, hsa-mir-1264, hsa-mir-4418, hsa-mir-4497, hsa-mir-4485-3p, hsa-mir-4715-3p, hsa-mir-4433-3p, hsa-mir-4708-3p, hsa-mir-1973 and hsa-mir-564 were upregulated, ranging from 20-0.8-fold. We carried out target gene alignment of these miRNAs with the ZIKV genome to predict the function of the differentially expressed miRNAs and their potential impact on ZIKV pathogenesis. These miRNAs might prove useful as novel diagnostic or therapeutic markers and targets for further research on ZIKV infection and neuronal injury resulting from ZIKV infectivity in developing fetal brain neurons.

Knowledge of Zika Virus Transmission and Its Prevention among High-Risk Pregnant Women in Brazil

Recent outbreaks of Zika virus (ZIKV) infection highlight the urgent need to evaluate the efficacy of current public health measures to educate susceptible groups about how to prevent infection, modes of viral transmission, and consequences of infection. We performed a cross-sectional study in the city of Jundiaí, São-Paulo, from March 2016 to August 2017. In 315 high-risk pregnant women we evaluated the rate of ZIKV infection, knowledge of pathways of ZIKV transmission, and the use of protective measures. Data were analyzed and correlated with sociodemographic variables. The rate of ZIKV infection was 10.8%. ZIKV transmission by mosquitoes was the best-known means of virus acquisition, while transmission of ZIKV by sexual intercourse as well as mother–fetus transmission was known by less than half of the women. The use of insect repellent, reported by 53% of participants, was correlated with higher education and personal directives from health professionals. Condom use was reported by 19.5% of subjects. Improved strategies to increase awareness of ZIKV infection and its consequences, designed to appeal to specific, targeted populations, are clearly necessary to more accurately prevent the spread of this infection and diminish adverse consequences in the pregnant population.