Dengue and Zika viruses: lessons learned from the similarities between these Aedes mosquito-vectored arboviruses

Antiviral activity of myricetin glycosylated compounds isolated from Marcetia taxifolia against chikungunya virus

The chikungunya virus (CHIKV) has produced epidemic outbreaks of significant public health impact. The clinical symptoms of this disease are fever, polyarthralgia, and skin rash, generally self-limiting, although patients may develop a chronic disabling condition or suffer lethal complications. Unfortunately, there is no specific treatment or vaccine available. Thus, the search for effective therapies to control CHIKV infection is an urgent need. This study evaluated the antiviral activity of flavonoids isolated from Marcetia taxifolia by in vitro and in silico analysis. Cytotoxicity of compounds was determined by MTT assay and viral load was assessed in cell substrates supernatants by plaque-forming and RT-qPCR assays. Selected molecules were analyzed by molecular docking assays. Myricetin 3-rhamnoside (MR) and myricetin 3-(6-rhamnosylgalactoside) (MRG) were tested for antiviral assays and analyzed by the TCID50 method and RT-qPCR. MR exhibited dose-dependent antiviral activity, reducing viral titer at concentrations of 150-18.8 μg/mL by at least 1-log. Similarly, MRG showed a significant decrease in viral titer at concentrations of 37.5, 9.4, and 2.3 μg/mL. RT-qPCR analysis also displayed a substantial reduction of CHIKV RNA for both flavonoids. Furthermore, molecular docking of the selected flavonoids proposed the nsP3 macrodomain as a possible target of action. Our study reveals that MR and MRG could be considered promising anti-CHIKV therapeutic agents. Molecular modeling studies showed MR and MRG ligands with a high affinity for the N-terminal region of the nsP3 macrodomain, postulating them as a potential target of action for the CHIKV control.

Cholesterol-Lowering Drugs as Potential Antivirals: A Repurposing Approach against Flavivirus Infections

Flaviviruses, including Dengue (DENV), Zika (ZIKV), and Yellow Fever (YFV) viruses, represent a significant global health burden. The development of effective antiviral therapies against these viruses is crucial to mitigate their impact. This study investigated the antiviral potential of the cholesterol-lowering drugs atorvastatin and ezetimibe in monotherapy and combination against DENV, ZIKV, and YFV. In vitro results demonstrated a dose-dependent reduction in the percentage of infected cells for both drugs. The combination of atorvastatin and ezetimibe showed a synergistic effect against DENV 2, an additive effect against DENV 4 and ZIKV, and an antagonistic effect against YFV. In AG129 mice infected with DENV 2, monotherapy with atorvastatin or ezetimibe significantly reduced clinical signs and increased survival. However, the combination of both drugs did not significantly affect survival. This study provides valuable insights into the potential of atorvastatin and ezetimibe as antiviral agents against flaviviruses and highlights the need for further investigations into their combined therapeutic effects.

Trends in ELISA-Based Flavivirus IgG Serosurveys: A Systematic Review

Flaviviruses include virus species that are major public health threats worldwide. To determine the immunity landscape of these viruses, seroprevalence studies are often performed using IgG ELISA, which is a simple and rapid alternative to the virus neutralization test. In this review, we aim to describe the trends in flavivirus IgG ELISA-based serosurveys. A systematic literature review using six databases was performed to collate cohort and cross-sectional studies performed on the general population. A total of 204 studies were included in this review. The results show that most studies were performed on dengue virus (DENV), whereas Japanese Encephalitis Virus (JEV) was the least studied. For geographic distribution, serosurveys followed known disease prevalence. Temporally, the number of serosurveys increased after outbreaks and epidemics except for JEV, for which studies were performed to demonstrate the effectiveness of vaccination campaigns. Commercial kits were more commonly used than in-house assays for DENV, West Nile Virus (WNV), and Zika virus (ZIKV). Overall, most studies employed an indirect ELISA format, and the choice of antigens varied per virus. This review shows that flavivirus epidemiology is related to the regional and temporal distribution of serosurveys. It also highlights that endemicity, cross-reactivities, and kit availabilities affect assay choice in serosurveys.

The Aedes aegypti siRNA pathway mediates broad-spectrum defense against human pathogenic viruses and modulates antibacterial and antifungal defenses

The mosquito's innate immune system defends against a variety of pathogens, and the conserved siRNA pathway plays a central role in the control of viral infections. Here, we show that transgenic overexpression of Dicer2 (Dcr2) or R2d2 resulted in an accumulation of 21-nucleotide viral sequences that was accompanied by a significant suppression of dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) replication, thus indicating the broad-spectrum antiviral response mediated by the siRNA pathway that can be applied for the development of novel arbovirus control strategies. Interestingly, overexpression of Dcr2 or R2d2 regulated the mRNA abundance of a variety of antimicrobial immune genes, pointing to additional functions of DCR2 and R2D2 as well as cross-talk between the siRNA pathway and other immune pathways. Accordingly, transgenic overexpression of Dcr2 or R2d2 resulted in a lesser proliferation of the midgut microbiota and increased resistance to bacterial and fungal infections.

Cross-reactive antibodies facilitate innate sensing of dengue and Zika viruses

The Aedes aegypti mosquito transmits both dengue (DENV) and Zika (ZIKV) viruses. Individuals in endemic areas are at risk for infection with both viruses as well as repeated DENV infection. In the presence of anti-DENV antibodies, outcomes of secondary DENV infection range from mild to life-threatening. Further, the role of cross-reactive antibodies on the course of ZIKV infection remains unclear.We assessed the ability of cross-reactive DENV monoclonal antibodies or polyclonal immunoglobulin isolated after DENV vaccination to upregulate type I interferon (IFN) production by plasmacytoid dendritic cells (pDCs) in response to both heterotypic DENV- and ZIKV- infected cells. We found a range in the ability of antibodies to increase pDC IFN production and a positive correlation between IFN production and the ability of an antibody to bind to the infected cell surface. Engagement of Fc receptors on the pDC and Fab binding of an epitope on infected cells was required to mediate increased IFN production by providing specificity to and promoting pDC sensing of DENV or ZIKV. This represents a mechanism independent of neutralization by which pre-existing cross-reactive DENV antibodies could protect a subset of individuals from severe outcomes during secondary heterotypic DENV or ZIKV infection.

Conserved motifs in the flavivirus NS3 RNA helicase enzyme

Flaviviruses are a major health concern because over half of the world population is at risk of infection and there are very few antiviral therapeutics to treat diseases resulting from infection. Replication is an essential part of the flavivirus survival. One of the viral proteins, NS3 helicase, is critical for unwinding the double stranded RNA intermediate during flaviviral replication. The helicase performs the unwinding of the viral RNA intermediate structure in an ATP-dependent manner. NS3 helicase is a member of the Viral/DEAH-like subfamily of the superfamily 2 helicase containing eight highly conserved structural motifs (I, Ia, II, III, IV, IVa, V, and VI) localized between the ATP-binding and RNA-binding pockets. Of these structural motifs only three are well characterized for function in flaviviruses (I, II, and VI). The roles of the other structural motifs are not well understood for NS3 helicase function, but comparison of NS3 with other superfamily 2 helicases within the viral/DEAH-like, DEAH/RHA, and DEAD-box subfamilies can be used to elucidate the roles of these structural motifs in the flavivirus NS3 helicase. This review aims to summarize the role of each conserved structural motif within flavivirus NS3 in RNA helicase function. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease.

New insights into the recombinant proteins and monoclonal antibodies employed to immunodiagnosis and control of Zika virus infection: A review

An emergent positive-stranded RNA virus, transmitted by mosquitoes with its first case of vertical transmission confirmed in 2015 in Brazil. The Zika virus (ZIKV) fever has received particular attention, mainly related to neurological diseases such as microcephaly in newborns. However, the laboratory diagnosis for ZIKV still faces some challenges due to its cross-reactivity with other flaviviruses, requiring a correct and differential diagnosis, contributing to the good prognosis of patients, especially in pregnant women. Among these, for early diagnosis, the CDC considers the RT-PCR the gold standard, more sensitive and specific, but expensive. Serological tests for the diagnosis of ZIKV can also be found beyond the period when the viral components are detectable in the serum. Inputs to produce more sensitive and specific diagnostic kits and the possibility of viral detection in less invasive samples are among the objectives of recent research on ZIKV. This review outlines recent advances in developing recombinant antigen and antibody-based diagnostic tools for the main flaviviruses in Northeast Brazil, such as ZIKV and Dengue virus (DENV).

Interplay between autophagy and Sindbis virus in cells derived from key arbovirus vectors, Aedes albopictus and Aedes aegypti mosquitoes

Aedes albopictus and Aedes aegypti are two species of Aedes mosquitoes which transmit multiple arboviruses causing serious diseases in human. Intriguingly, infection of arbovirus in both Aedes mosquitoes does not cause dramatic pathology, indicating that both mosquitoes have evolved mechanisms to tolerate persistent infection and restrict viral replication to nonpathogenic levels. Therefore, understanding how these mosquitoes interact with viruses would help to find targets for controlling the related mosquito-borne diseases. Autophagy is a conserved cellular recycling process functioning in maintenance of cellular homeostasis and recirculation of cytoplasmic materials under stressful conditions. Autophagy also acts as a cellular defense mechanism against viral infection. It is known that autophagy plays important roles in the replication of several Aedes mosquito-borne viruses in mammalian systems. However, little information is available regarding the role of autophagy in replication of those viruses in their primary vector, Aedes mosquitoes. This study found that interaction between autophagy and replication of Sindbis virus (SINV) occurred in Aedes albopictus C6/36 cells and Ae. aegypti Aag2 cells. Moreover, it discovered that the patterns of interaction between autophagy and SINV replication are different in C6/36 cells and Aag2 cells. It was shown that replication of SINV induced complete autophagy in C6/36 cells but suppressed autophagy in Aag2 cells. Moreover, induction of autophagy by rapamycin treatment restricted SINV replication in C6/36 cells but promoted SINV replication in Aag2 cells. Consistent with this, suppression of autophagy by down regulation of Atg8 promoted SINV replication in C6/36 cells but restricted SINV replication in Aag2 cells. It was also found that, in both C6/36 and Aag2 cells, interaction between autophagy and SINV replication occurred after viral entry and prior to viral assembly. Collectively, this work demonstrated that SINV replication manipulated autophagy in Aedes mosquito cells and provided strong evidence of the role autophagy played in viral replication in Aedes mosquitoes. The findings have laid a foundation to elucidate the correlation between autophagy and arbovirus replication in Aedes mosquitoes and could help to understand the difference in viral transmission capacity of the two Aedes mosquitoes, Ae. albopictus and Ae. aegypti.

Dengue and Zika virus infection patterns vary among Aedes aegypti field populations from Belo Horizonte, a Brazilian endemic city

Dengue virus (DENV) and Zika virus (ZIKV) belong to the same viral family, the Flaviviridae. They cause recurring threats to the public health systems of tropical countries such as Brazil. The primary Brazilian vector of both viruses is the mosquito Aedes aegypti. After the mosquito ingests a blood meal from an infected person, the viruses infect and replicate in the midgut, disseminate to secondary tissues and reach the salivary gland (SG), where they are ready to be transmitted to a vertebrate host. It is thought that the intrinsic discrepancies among mosquitoes could affect their ability to deal with viral infections. This study confirms that the DENV and ZIKV infection patterns of nine Ae. aegypti field populations found in geographically separate health districts of an endemic Brazilian city vary. We analyzed the infection rate, disseminated infection, vector competence, and viral load through quantitative PCR. Mosquitoes were challenged using the membrane-feeding assay technique and were tested seven and fourteen days post-infection (early and late infection phases, respectively). The infection responses varied among the Ae. aegypti populations for both flaviviruses in the two infection phases. There was no similarity between DENV and ZIKV vector competencies or viral loads. According to the results of our study, the risk of viral transmission overtime after infection either increases or remains unaltered in ZIKV infected vectors. However, the risk may increase, decrease, or remain unaltered in DENV-infected vectors depending on the mosquito population. For both flaviviruses, the viral load persisted in the body even until the late infection phase. In contrast to DENV, the ZIKV accumulated in the SG over time in all the mosquito populations. These findings are novel and may help direct the development of control strategies to fight dengue and Zika outbreaks in endemic regions, and provide a warning about the importance of understanding mosquito responses to arboviral infections.

Dengue and Zika are neglected diseases caused by viruses transmitted to humans by mosquitoes (vector-borne diseases). The primary vector of both diseases is Aedes aegypti, a highly abundant mosquito in tropical countries and adapted to the urban habitat. The viral cycle in the vector starts when the mosquito bites an infected person and acquires the viruses through the blood meal. When the infected blood reaches the mosquito’s midgut, the viruses invade the epithelial cells and disseminate in several organs until they reach the salivary glands, enabling viral transmission to the next person. However, the mosquitoes have developed strategies to combat the viral invasion and dissemination in their body, making this journey a challenge to the viruses. Herein, we show that the mosquito responses against dengue and Zika viruses are distinct. In addition, mosquitoes from separate populations of the same city have different abilities to deal with the viruses in both cases, dengue and Zika infections. Our results show the diversity of responses that the mosquitoes may present to viral infections. These findings may better direct disease control strategies to combat dengue and Zika outbreaks in endemic regions.

The limited knowledge of placental damage due to neglected infections: ongoing problems in Latin America

The placenta works as a selective barrier, protecting the fetus from potential infections that may affect the maternal organism during pregnancy. In this review, we will discuss several challenging infections that are common within Latin American countries and that may affect the maternal-fetal interface and pose risks to fetal development. Specifically, we will focus on emerging infectious diseases including the arboviruses, malaria, leishmaniasis, and the bacterial foodborne disease caused by Shiga toxin-producing Escherichia coli. We will also highlight some topics of interest currently being studied by research groups that comprise an international effort aimed at filling the knowledge gaps in this field. These topics address the relationship between exposure to microorganisms and placental abnormalities, congenital anomalies, and complications of pregnancy.

ABBREVIATIONS

ADE: antibody-dependent enhancement; CCL2: monocyte chemoattractant protein-1; CCL3: macrophage inflammatory protein-1 α; CCL5: chemokine (C-C motif) ligand 5; CHIKV: chikungunya virus; DCL: diffuse cutaneous leishmaniasis; DENV: dengue virus; Gb3: glycolipid globotriaosylceramyde; HIF: hypoxia-inducible factor; HUS: hemolytic uremic syndrome; IFN: interferon; Ig: immunoglobulins; IL: interleukin; IUGR: intrauterine growth restriction; LCL: localized cutaneous leishmaniasis; LPS: lipopolysaccharid; MCL: mucocutaneous leishmaniasis; NO: nitric oxide; PCR: polymerase chain reaction; PGF: placental growth factor; PM: placental malaria; RIVATREM: Red Iberoamericana de Alteraciones Vasculares em transtornos del Embarazo; sVEGFR: soluble vascular endothelial growth factor receptor; STEC: shiga toxin-producing Escherichia coli; stx: shiga toxin protein; TNF: tumor necrosis factor; TOAS: T cell original antigenic sin; Var2CSA: variant surface antigen 2-CSA; VEGF: vascular endothelial growth factor; VL: visceral leishmaniasis; WHO: world health organization; YFV: yellow fever virus; ZIKV: Zika virus.

An Integrated Systems Biology Approach Identifies the Proteasome as A Critical Host Machinery for ZIKV and DENV Replication

The Zika virus (ZIKV) and dengue virus (DENV) flaviviruses exhibit similar replicative processes but have distinct clinical outcomes. A systematic understanding of virus-host protein-protein interaction networks can reveal cellular pathways critical to viral replication and disease pathogenesis. Here we employed three independent systems biology approaches toward this goal. First, protein array analysis of direct interactions between individual ZIKV/DENV viral proteins and 20,240 human proteins revealed multiple conserved cellular pathways and protein complexes, including proteasome complexes. Second, an RNAi screen of 10,415 druggable genes identified the host proteins required for ZIKV infection and uncovered that proteasome proteins were crucial in this process. Third, high-throughput screening of 6016 bioactive compounds for ZIKV inhibition yielded 134 effective compounds, including six proteasome inhibitors that suppress both ZIKV and DENV replication. Integrative analyses of these orthogonal datasets pinpoint proteasomes as critical host machinery for ZIKV/DENV replication. Our study provides multi-omics datasets for further studies of flavivirus-host interactions, disease pathogenesis, and new drug targets.

SARS-CoV-2 and arbovirus infection: a rapid systematic review

BACKGROUND

The numbers of cases of arboviral diseases have increased in tropical and subtropical regions while the coronavirus disease (COVID-19) pandemic overwhelms healthcare systems worldwide. The clinical manifestations of arboviral diseases, especially dengue fever, can be very similar to COVID-19, and misdiagnoses are still a reality. In the meantime, outcomes for patients and healthcare systems in situations of possible syndemic have not yet been clarified.

OBJECTIVE

We set out to conduct a systematic review to understand and summarize the evidence relating to clinical manifestations, disease severity and prognoses among patients coinfected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and arboviruses.

METHODS

We conducted a rapid systematic review with meta-analysis, on prospective and retrospective cohorts, case-control studies and case series of patients with confirmed diagnoses of SARS-CoV-2 and arboviral infection. We followed the Cochrane Handbook recommendations. We searched EMBASE, MEDLINE, Cochrane Library, LILACS, Scopus and Web of Science to identify published, ongoing and unpublished studies. We planned to extract data and assess the risk of bias and the certainty of evidence of the studies included, using the Quality in Prognosis Studies tool and the Grading of Recommendations Assessment.

RESULTS

We were able to retrieve 2,407 citations using the search strategy, but none of the studies fulfilled the inclusion criteria.

CONCLUSION

The clinical presentations, disease severity and prognoses of patients coinfected with SARS-CoV-2 and arboviruses remain unclear. Further prospective studies are necessary in order to provide useful information for clinical decision-making processes.

PROTOCOL REGISTRATION NUMBER IN THE PROSPERO DATABASE

CRD42020183460.

Andrographolide and Its 14-Aryloxy Analogues Inhibit Zika and Dengue Virus Infection

Andrographolide is a labdene diterpenoid with potential applications against a number of viruses, including the mosquito-transmitted dengue virus (DENV). In this study, we evaluated the anti-viral activity of three 14-aryloxy analogues (ZAD-1 to ZAD-3) of andrographolide against Zika virus (ZIKV) and DENV. Interestingly, one analogue, ZAD-1, showed better activity against both ZIKV and DENV than the parental andrographolide. A two-dimension (2D) proteomic analysis of human A549 cells treated with ZAD-1 compared to cells treated with andrographolide identified four differentially expressed proteins (heat shock 70 kDa protein 1 (HSPA1A), phosphoglycerate kinase 1 (PGK1), transketolase (TKT) and GTP-binding nuclear protein Ran (Ran)). Western blot analysis confirmed that ZAD-1 treatment downregulated expression of HSPA1A and upregulated expression of PGK1 as compared to andrographolide treatment. These results suggest that 14-aryloxy analogues of andrographolide have the potential for further development as anti-DENV and anti-ZIKV agents.

Wolbachia's Deleterious Impact on Aedes aegypti Egg Development: The Potential Role of Nutritional Parasitism

Simple Summary

Mosquito-borne viral diseases such as dengue, Zika and chikungunya cause a significant global health burden and are currently increasing in outbreak frequency and geographical reach. Wolbachia pipientis, an endosymbiotic bacterium, offers a solution to this. When Wolbachia is introduced into the main mosquito vector of these viruses, Aedes aegypti, it alters the mosquito’s reproductive biology, as well as reducing the ability of the mosquitoes to transmit viruses. These traits can be leveraged to reduce virus transmission within a community by mass releasing Wolbachia-infected mosquitoes. However, Wolbachia has some negative effects on Aedes aegypti fitness, particularly egg longevity, and the reason behind this remains ambiguous. Insect fitness is very important for the success for Wolbachia-biocontrol strategies as they rely on the released insects being competitive with the wild mosquito population. This review summarises the fitness effects of Wolbachia on Aedes aegypti and investigates the possible contribution of Wolbachia as a nutritional parasite in lowering host fitness. It proposes the next stages of research that can be conducted to address nutritional parasitism to aid in the expansion of Wolbachia-based disease management programs worldwide.

Abstract

The artificial introduction of the endosymbiotic bacterium, Wolbachia pipientis, into Aedes (Ae.) aegypti mosquitoes reduces the ability of mosquitoes to transmit human pathogenic viruses and is now being developed as a biocontrol tool. Successful introgression of Wolbachia-carrying Ae. aegypti into native mosquito populations at field sites in Australia, Indonesia and Malaysia has been associated with reduced disease prevalence in the treated community. In separate field programs, Wolbachia is also being used as a mosquito population suppression tool, where the release of male only Wolbachia-infected Ae. aegypti prevents the native mosquito population from producing viable eggs, subsequently suppressing the wild population. While these technologies show great promise, they require mass rearing of mosquitoes for implementation on a scale that has not previously been done. In addition, Wolbachia induces some negative fitness effects on Ae. aegypti. While these fitness effects differ depending on the Wolbachia strain present, one of the most consistent and significant impacts is the shortened longevity and viability of eggs. This review examines the body of evidence behind Wolbachia’s negative effect on eggs, assesses nutritional parasitism as a key cause and considers how these impacts could be overcome to achieve efficient large-scale rearing of these mosquitoes.

7X multiplexed, optofluidic detection of nucleic acids for antibiotic-resistance bacterial screening

Rapid and accurate diagnosis of bacterial infections resistant to multiple antibiotics requires development of new bio-sensors for differentiated detection of multiple targets. This work demonstrates 7x multiplexed detection for antibiotic-resistance bacterial screening on an optofluidic platform. We utilize spectrally multiplexed multi-spot excitation for simultaneous detection of nucleic acid strands corresponding to bacterial targets and resistance genes. This is enabled by multi-mode interference (MMI) waveguides integrated in an optofluidic device. We employ a combinatorial three-color labeling scheme for the nucleic acid assays to scale up their multiplexing capability to seven different nucleic acids, representing three species and four resistance genes.

An antibody panel for highly specific detection and differentiation of Zika virus

Zika virus (ZIKV) is an emerging flavivirus transmitted to humans by Aedes mosquitos. ZIKV can be transmitted from mother to fetus during pregnancy and can cause microcephaly and other birth defects. Effective vaccines for Zika are yet to be approved. Detection of the ZIKV is based on serological testing that often shows cross-reactivity with the Dengue virus (DENV) and other flaviviruses. We aimed to assemble a highly specific anti-Zika antibody panel to be utilized in the development of a highly specific and cost-effective ZIKV rapid quantification assay for viral load monitoring at point-of-care settings. To this end, we tested the affinity and specificity of twenty one commercially available monoclonal and polyclonal antibodies against ZIKV and DENV envelope proteins utilizing nine ZIKV and twelve DENV strains. We finalized and tested a panel of five antibodies for the specific detection and differentiation of ZIKV and DENV infected samples.

Development of a Cell-Based Immunodetection Assay for Simultaneous Screening of Antiviral Compounds Inhibiting Zika and Dengue Virus Replication

Practical cell-based assays can accelerate anti-Zika (ZIKV) and anti-dengue (DENV) virus drug discovery. We developed an immunodetection assay (IA), using a pan-flaviviral monoclonal antibody recognizing a conserved envelope domain. The final protocol includes a direct virus yield reduction assay (YRA) carried out in the human Huh7 cell line, followed by transfer of the supernatant to a secondary Huh7 culture to characterize late antiviral effects. Sofosbuvir and ribavirin were used to validate the assay, while celgosivir was used to evaluate the ability to discriminate between early and late antiviral activity. In the direct YRA, at 100, 50, and 25 TCID₅₀, sofosbuvir IC₅₀ values were 5.0 ± 1.5, 2.7 ± 0.5, 2.5 ± 1.1 µM against ZIKV and 16.6 ± 2.8, 4.6 ± 1.4, 2.6 ± 2.2 µM against DENV; ribavirin IC₅₀ values were 6.8 ± 4.0, 3.8 ± 0.6, 4.5 ± 1.4 µM against ZIKV and 17.3 ± 4.6, 7.6 ± 1.2, 4.1 ± 2.3 µM against DENV. Sofosbuvir and ribavirin IC₅₀ values determined in the secondary YRA were reproducible and comparable with those obtained by direct YRA and plaque reduction assay (PRA). In agreement with the proposed mechanism of late action, celgosivir was active against DENV only in the secondary YRA (IC₅₀ 11.0 ± 1.0 µM) and in PRA (IC₅₀ 10.1 ± 1.1 µM). The assay format overcomes relevant limitations of the gold standard PRA, allowing concurrent analysis of candidate antiviral compounds against different viruses and providing preliminary information about early versus late antiviral activity.

Tryptophan Trimers and Tetramers Inhibit Dengue and Zika Virus Replication by Interfering with Viral Attachment Processes

Here, we report a class of tryptophan trimers and tetramers that inhibit (at low micromolar range) dengue and Zika virus infection in vitro These compounds (AL family) have three or four peripheral tryptophan moieties directly linked to a central scaffold through their amino groups; thus, their carboxylic acid groups are free and exposed to the periphery. Structure-activity relationship (SAR) studies demonstrated that the presence of extra phenyl rings with substituents other than COOH at the N1 or C2 position of the indole side chain is a requisite for the antiviral activity against both viruses. The molecules showed potent antiviral activity, with low cytotoxicity, when evaluated on different cell lines. Moreover, they were active against laboratory and clinical strains of all four serotypes of dengue virus as well as a selected group of Zika virus strains. Additional mechanistic studies performed with the two most potent compounds (AL439 and AL440) demonstrated an interaction with the viral envelope glycoprotein (domain III) of dengue 2 virus, preventing virus attachment to the host cell membrane. Since no antiviral agent is approved at the moment against these two flaviviruses, further pharmacokinetic studies with these molecules are needed for their development as future therapeutic/prophylactic drugs.

The prevention of arboviral diseases using mobile devices: a preliminary study of the attitudes and behaviour change produced by educational interventions

OBJECTIVES

In Brazil, the National Policy for Dengue Control seeks to incorporate the lessons of national and international experience in dengue control, emphasising the need for health education activities. The objective of this study was to evaluate and compare knowledge, attitudes and behaviours related to the prevention of arboviruses before and after a two-month educational intervention using a learning platform on mobile devices.

METHODS

This quasi-experimental study corresponds to the first phase of the project 'Impact of mobile learning in the prevention and management of complications caused by arboviruses (Zika, Dengue, Chikungunya) - ZIKAMOB', sponsored as part of the British Council Newton Fund.

RESULTS

Thirty of the 93 participants were first-year undergraduate university students (36.7% male), and 63 were police officers (84.1% male). The pattern of attitudes and behaviour was very similar in both groups before the intervention. The students changed their attitudes and behaviour (P = 0.032) in relation to their engagements in actions for the prevention of arboviral diseases and several other activities related to house inspections and precautions with water tanks (P < 0.01). However, recycling and surveillance activities were not as effective in changing behaviour. Female participants showed more motivation to participate in preventive activities, but living alone and working were barriers to participation. Individuals who already perform selective waste collection and are cultivating gardens demonstrated both a positive attitude and a positive behaviour towards actions for the prevention of arboviral diseases.

CONCLUSION

Mobile learning and behaviour change theories might be successful as the basis for school-based and community-based interventions to avoid arboviruses. These outcomes need to be confirmed in broader future studies.

Molecular characteristics and replication mechanism of dengue, zika and chikungunya arboviruses, and their treatments with natural extracts from plants: An updated review

Viruses transmitted by arthropods (arboviruses) are the etiological agents of several human diseases with worldwide distribution; including dengue (DENV), zika (ZIKV), yellow fever (YFV), and chikungunya (CHIKV) viruses. These viruses are especially important in tropical and subtropical regions; where, ZIKV and CHIKV are involved in epidemics worldwide, while the DENV remains as the biggest problem in public health. Factors, such as, environmental conditions promote the distribution of vectors, deficiencies in health services, and lack of effective vaccines, guarantee the presence of these vector-borne diseases. Treatment against these viral diseases is only palliative since available therapies formulated lack to demonstrate specific antiviral activity and vaccine candidates fail to demonstrate enough effectiveness. The use of natural products, as therapeutic tools, is an ancestral practice in different cultures. According to WHO 80 % of the population of some countries from Africa and Asia depend on the use of traditional medicines to deal with some diseases. Molecular characteristics of these viruses are important in determining its cellular pathogenesis, emergence, and dispersion mechanisms, as well as for the development of new antivirals and vaccines to control strategies. In this review, we summarize the current knowledge of the molecular structure and replication mechanisms of selected arboviruses, as well as their mechanism of entry into host cells, and a brief overview about the potential targets accessed to inhibit these viruses in vitro and a summary about their treatment with natural extracts from plants.

Influence of directional positive Darwinian selection-driven evolution on arboviruses Dengue and Zika virulence and pathogenesis

Dengue (DENV) and Zika (ZIKV) viruses are antigenically and evolutionarily related; immunological cross-reactions between them have been associated to both cross-protection and infection-enhanced mechanisms. Here, DENV-1-4 and ZIKV were investigated through Bayesian coalescent-based approaches and selection-driven Darwinian evolution methods using robust datasets. Our findings show that both DENV and ZIKV, driven essentially by directional positive selection, have undergone evolution and diversification and that their entire polyproteins are subject to an intense directional evolution. Interestingly, positively selected codons mapped here are directly associated to DENV-1-2 virulence as well as the ZIKV burgeoning 2015-16 outbreak in the Americas, therefore, having impact on the pathogenesis of these viruses. Biochemical prediction analysis focusing on markers involved in virulence and viral transmission dynamics identified alterations in N-Glycosylation-, Phosphorylation- and Palmitoylation-sites in ZIKV sampled from different countries, hosts and isolation sources. Taking into account both DENV-ZIKV co-circulation either into and/or out of flavivirus-endemic regions, as well as recombination and quasispecies scenarios, these results indicate the action of a selection-driven evolution affecting the biology, virulence and pathogenesis of these pathogens in a non-randomized environment.

Multiplexed kit based on Luminex technology and achievements in synthetic biology discriminates Zika, chikungunya, and dengue viruses in mosquitoes

Background

The global expansion of dengue (DENV), chikungunya (CHIKV), and Zika viruses (ZIKV) is having a serious impact on public health. Because these arboviruses are transmitted by the same mosquito species and co-circulate in the same area, a sensitive diagnostic assay that detects them together, with discrimination, is needed.

Methods

We present here a diagnostics panel based on reverse transcription-PCR amplification of viral RNA and an xMap Luminex architecture involving direct hybridization of PCRamplicons and virus-specific probes. Two DNA innovations (“artificially expanded genetic information systems”, AEGIS, and “self-avoiding molecular recognition systems”, SAMRS) increase the hybridization sensitivity on Luminex microspheres and PCR specificity of the multiplex assay compared to the standard approach (standard nucleotides).

Results

The diagnostics panel detects, if they are present, these viruses with a resolution of 20 genome equivalents (DENV1), or 10 (DENV3–4, CHIKV) and 80 (DENV2, ZIKV) genome equivalents per assay. It identifies ZIKV, CHIKV and DENV RNAs in a single infected mosquito, in mosquito pools comprised of 5 to 50 individuals, and mosquito saliva (ZIKV, CHIKV, and DENV2). Infected mosquitoes and saliva were also collected on a cationic surface (Q-paper), which binds mosquito and viral nucleic acids electrostatically. All samples from infected mosquitoes displayed only target-specific signals; signals from non-infected samples were at background levels.

Conclusions

Our results provide an efficient and multiplex tool that may be used for surveillance of emerging mosquito-borne pathogens which aids targeted mosquito control in areas at high risk for transmission.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3998-z) contains supplementary material, which is available to authorized users.

Designing Paper-Based Immunoassays for Biomedical Applications

Paper-based sensors and assays have been highly attractive for numerous biological applications, including rapid diagnostics and assays for disease detection, food safety, and clinical care. In particular, the paper immunoassay has helped drive many applications in global health due to its low cost and simplicity of operation. This review is aimed at examining the fundamentals of the technology, as well as different implementations of paper-based assays and discuss novel strategies for improving their sensitivity, performance, or enabling new capabilities. These innovations can be categorized into using unique nanoparticle materials and structures for detection via different techniques, novel biological species for recognizing biomarkers, or innovative device design and/or architecture.

Identification of AaAtg8 as a marker of autophagy and a functional autophagy-related protein in Aedes albopictus

Aedes albopictus is a primary vector of hundreds of pathogens. Strong environmental adaptability and extensive global distribution of Aedes albopictus make it a severe threat to human health. Autophagy is a cellular process involved in maintenance of cellular homeostasis and recirculation of cytoplasm to generate macromolecule constituents and energy under different stress conditions. Many autophagy-related (Atg) proteins have been identified in yeast and were found in various organisms subsequently, indicating that the basic mechanism of autophagy is well conserved in eukaryotes. Among all Atg proteins, Atg8 plays important roles in autophagy and is widely used as a marker to monitor autophagic activity in yeast, Drosophila, nematodes, zebrafish and mammals. By now, Atg proteins in Aedes albopictus have not been reported yet and the autophagy pathway in Aedes albopictus remains unclear. This study identified a homolog of Atg8 from Aedes albopictus and named it AaAtg8. Sequence analysis revealed that AaAtg8 was highly conserved in the Atg8 family. This work proved that AaAtg8 was a functional Atg protein of Aedes albopictus and expressed during developmental and adult stages of Aedes albopictus. Moreover, the study also established the basic methods for autophagy study in C6/36 cells. First, it was proved that both rapamycin and starvation were applicable ways to induce autophagy in C6/36 cells, and that 3-methyladenine and chloroquine could be used to inhibit early and late stages of autophagy in C6/36 cells, respectively. Second, the results in this study showed that monodansylcadaverine staining could be used to detect autophagy in C6/36 cells. Additionally, the study revealed that the level of autophagy in C6/36 cells could be monitored by the turnover assay of AaAtg8 or fluorescent AaAtg8. Taken together, this study identified AaAtg8, the first reported Atg protein in Aedes albopictus. It also provided useful methods for studying autophagy in Aedes albopictus. To our knowledge, this is the first work about autophagy in Aedes albopictus.

Zika Virus Vaccines: Challenges and Perspectives

Zika virus is an arbovirus that has rapidly spread within the Americas since 2014, presenting a variety of clinical manifestations and neurological complications resulting in congenital malformation, microcephaly, and possibly, in male infertility. These significant clinical manifestations have led investigators to develop several candidate vaccines specific to Zika virus. In this review we describe relevant targets for the development of vaccines specific for Zika virus, the development status of various vaccine candidates and their different platforms, as well as their clinical progression.

Emerging sexually transmitted viral infections: 2. Review of Zika virus disease

A sudden increase in the number of newborn infants with microcephaly in Brazil in 2015 brought Zika virus (ZIKV), a less-known infection, to public attention. The rapid increase in the number of cases across the Americas and the devastating complications of infection with ZIKV highlighted the gravity of the situation. Within a relatively short period of time, our knowledge of this infection has significantly increased. This includes the realisation that ZIKV can be sexually transmitted. The aim of the present article is to provide a concise summary on this novel sexually transmitted infection linked to human birth defects and Guillain-Barre Syndrome. According to World Health Organization, individuals living outside areas of ZIKV mosquito transmission where one or both partners have been exposed to ZIKV should abstain from sex or have sex with condoms for at least six months after the last day of possible exposure.

Diagnosis and outcomes of pregnant women with Zika virus infection in two municipalities of Risaralda, Colombia: Second report of the ZIKERNCOL study

BACKGROUND

Zika virus (ZIKV) infection has emerged as a significant threat for pregnant women and newborns in populations living in or visiting Latin America. We previously reported a preliminary analysis in Sucre, Colombia, as the first group of pregnant women with RT-PCR-confirmed ZIKV (ZIKa enEmbarazadas yReciénNacidos enCOLombia, ZIKERNCOL).

METHODS

In this second report, findings of the first 86 pregnant women from La Virginia and Dosquebradas (municipalities), Risaralda, Colombia, with RT-PCR-confirmed ZIKV infection are reported. Clinical, demographical and obstetrical findings are described.

RESULTS

All women reported ZIKV symptoms during pregnancy: 79.1% rash, 55.8% fever, among others. In addition to ZIKV, RT-PCR was positive for dengue in 18.6%; 45.3% Dengue IgM+; 5.8% RT-PCR positive for chikungunya; 3.6% Chikungunya IgM+. STORCH screening in mother: 11.6% IgG + anti-Toxoplasma gondii, 6% IgG + anti-rubella, 4.7% IgG + CMV. The rest of STORCH tests were negative. Microcephaly was observed in 2.4% of the newborns. No calcifications or other CNS alterations were detected. One newborn had cleft palate and one had bilateral renal ectopy.

CONCLUSIONS

The rate of microcephaly in our cohort was consistent with other studies. Pregnant women in endemic areas should be followed and tested according to standard protocols, and asymptomatic ZIKV infection should be considered. Long-term follow-up of children is required in the congenital Zika syndrome (CZS) assessment.

Vertical Transmission of the Zika Virus Causes Neurological Disorders in Mouse Offspring

The association between Zika virus (ZIKV) infection and congenital malformations such as microcephaly in infants is a public health emergency. Although various in vivo and in vitro models are used for ZIKV research, few animal models are available for resolving the effects of maternal ZIKV infection on neonatal development. Here, we established an immunocompetent mouse model via intrauterine inoculation. Our results confirmed that ZIKV, but not dengue virus, infection caused spontaneous abortions, brain malformations, ocular abnormalities, spinal cord defects and paralysis in mouse offspring. Aside from microcephaly and hippocampal dysplasia, eye abnormalities, including microphthalmia, thinner optic nerves, damaged retinae, and deficient visual projection, were also observed following ZIKV infection. Moreover, ZIKV-infected offspring showed a loss of alpha motor neurons in the spinal cord and cerebellar malformation, which may cause paralysis. ZIKV also impaired adult neurogenesis in neonatal mice. Due to its intact immunity, our rodent model can be used to systematically evaluate the impact of ZIKV on embryonic and neonatal development and to explore potential therapies.

After the epidemic: Zika virus projections for Latin America and the Caribbean

Background

Zika is one of the most challenging emergent vector-borne diseases, yet its future public health impact remains unclear. Zika was of little public health concern until recent reports of its association with congenital syndromes. By 3 August 2017 ∼217,000 Zika cases and ∼3,400 cases of associated congenital syndrome were reported in Latin America and the Caribbean. Some modelling exercises suggest that Zika virus infection could become endemic in agreement with recent declarations from the The World Health Organisation.

Methodology/Principal findings

We produced high-resolution spatially-explicit projections of Zika cases, associated congenital syndromes and monetary costs for Latin America and the Caribbean now that the epidemic phase of the disease appears to be over. In contrast to previous studies which have adopted a modelling approach to map Zika potential, we project case numbers using a statistical approach based upon reported dengue case data as a Zika surrogate. Our results indicate that ∼12.3 (0.7–162.3) million Zika cases could be expected across Latin America and the Caribbean every year, leading to ∼64.4 (0.2–5159.3) thousand cases of Guillain-Barré syndrome and ∼4.7 (0.0–116.3) thousand cases of microcephaly. The economic burden of these neurological sequelae are estimated to be USD ∼2.3 (USD 0–159.3) billion per annum.

Conclusions/Significance

Zika is likely to have significant public health consequences across Latin America and the Caribbean in years to come. Our projections inform regional and federal health authorities, offering an opportunity to adapt to this public health challenge.

In February 2016 the World Health Organisation (WHO) declared Zika virus infection in the Americas as a Public Health Emergency of International Concern (PHEIC). By November 2016, Zika was declared a long-term public health challenge. This change of status implies that Zika is likely to become an endemic problem in the region. Due to the PHEIC status of Zika, most current research has rightly focused on the epidemic stage of the disease; however, it is timely and critical to consider the public health consequences after such epidemic phase. We used one of the largest and most spatially diverse panels of epidemiological surveillance data comprising 12 years of dengue case observations from Brazil and Mexico, and covering an area of over ten million km². State-of-the-art statistical models, and high-resolution (0.5 × 0.5 degrees) climate and demographic data were used to produce spatially-explicit projections of Zika infection for Latin America and the Caribbean. Model projections were then used to estimate the number of cases with neurological sequelae and their economic cost. Our findings indicate that the potential health and economic burden of Zika could be considerably large for the region should it become endemic. The estimated burden of Zika under an endemic state highlights the need for health authorities in the countries at risk to promote preventive and control measures.

A review of selected Arboviruses during pregnancy

Arboviruses are emerging infectious diseases with the ability to expand geographically and rapidly affect large populations.

The recent epidemic caused by the Zika virus in the Americas and congenital Zika syndrome associated with maternal infection has called out attention to the importance of studying arboviruses during pregnancy.

This is a review on selected arboviruses infections during gestation, including Zika, Chikungunya, Dengue and Yellow Fever viruses. Issues such as historical overview, pathogenesis, transmission, clinical conditions, diagnosis, treatment and prevention are addressed.

Specific Biomarkers Associated With Neurological Complications and Congenital Central Nervous System Abnormalities From Zika Virus-Infected Patients in Brazil

Background

Zika virus (ZIKV) infections have been linked to different levels of clinical outcomes, ranging from mild rash and fever to severe neurological complications and congenital malformations.

Methods

We investigated the clinical and immunological response, focusing on the immune mediators profile in 95 acute ZIKV-infected adult patients from Campinas, Brazil. These patients included 6 pregnant women who later delivered during the course of this study. Clinical observations were recorded during hospitalization. Levels of 45 immune mediators were quantified using multiplex microbead-based immunoassays.

Results

Whereas 11.6% of patients had neurological complications, 88.4% displayed mild disease of rash and fever. Several immune mediators were specifically higher in ZIKV-infected patients, and levels of interleukin 10, interferon gamma-induced protein 10 (IP-10), and hepatocyte growth factor differentiated between patients with or without neurological complications. Interestingly, higher levels of interleukin 22, monocyte chemoattractant protein 1, TNF-α, and IP-10 were observed in ZIKV-infected pregnant women carrying fetuses with fetal growth–associated malformations. Notably, infants with congenital central nervous system deformities had significantly higher levels of interleukin 18 and IP-10 but lower levels of hepatocyte growth factor than those without such abnormalities born to ZIKV-infected mothers.

Conclusions

This study identified several key markers for the control of ZIKV pathogenesis. This will allow a better understanding of the molecular mechanisms of ZIKV infection in patients.

In vitro study of Zika virus infection in boar semen

Zika virus (ZIKV) is an important arbovirus that is capable of directly infecting neuronal cells. Infection can cause microcephaly in fetuses and Guillain-Barré syndrome in adults. Recent epidemiological studies have shown that ZIKV is sexually transmitted, especially from infected males to uninfected females. This study aimed to investigate the transmission pattern of ZIKV in semen using boar semen. Experiments were performed ex vivo using semen from healthy boar. The samples were infected with ZIKV, and viral RNA was detected and cell morphology was examined at different time points postinfection. ZIKV infection was confirmed by transmission electron microscopy. Viral RNA levels were found to markedly decrease as the time postinfection increased, without any evidence of virus replication. The sperm showed no significant changes in morphology. Transmission electron microscopy revealed the presence of virus-free sperm, suggesting that ZIKV cannot replicate in boar semen. We suggest three possible reasons underlying this phenomenon. First, the spermatozoa of boar might not be the target of ZIKV associated with sexual transmission. Second, the effect of the external environment on spermatozoa may affect ZIKV replication. Third, ZIKV may not be tropic for spermatozoa. This ex vivo study might be used as a platform to study the association of sexual transmission with ZIKV in other longer-lasting cells, such as Leydig or Sertoli cells.