Zika Virus: A Global Public Health Menace: A Comprehensive Update

Six new prenylated flavonoids from Dodonaea viscosa with anti-Zika virus activity

Six new prenylated flavonoids, named visconaeas A-F (1-6), and eleven known isopentenyl flavonoids (7-17) were isolated from Dodonaea viscosa (L.) Jacq. The structures of the separated compounds were determined through comprehensive spectral analysis and quantum chemical calculations. These compounds were tested for their anti-Zika virus and cytotoxicity activities. The results indicated that compound 4 showed low cytotoxicity and strong anti-Zika virus potential with EC50 16.34 μM.

Polypyrimidine Tract-Binding Protein Enhances Zika Virus Translation by Binding to the 5'UTR of Internal Ribosomal Entry Site

OBJECTIVES

To identify the 5' untranslated region of Zika virus (ZIKV 5'UTR) RNA-binding proteins and to investigate the impact of the binding protein on the activity of internal ribosomal entry site (IRES) located in ZIKV 5'UTR and virus production.

METHODS

Interacting proteins in U251 cells were captured using tRSA-tagged ZIKV 5'UTR RNA and tRSA-ZIKV 5'UTR RNA-binding proteins were visualized by SDS-PAGE silver staining. Subsequently, liquid chromatography-tandem mass spectrometry (LC-MS/MS), bioinformatics analysis, and Western blot were used to identify the candidate proteins binding to ZIKV 5'UTR. Dicistronic expression assay and plaque forming assay were performed to analyze the effect of the binding protein on ZIKV IRES activity and ZIKV production, respecitvely.

RESULTS

tRSA RNA pull-down assay, LC-MS/MS, and Western blot analysis showed that polypyrimidine tract-binding protein (PTB) bound to the ZIKV 5'UTR. Furthermore, dual luciferase reporter assay revealed that overexpression of PTB significantly enhanced the IRES activity of ZIKV (t = 10.220, P < 0.001), while PTB knockdown had the opposite effect (t = 4.897, P < 0.01). Additionally, virus plaque forming assay demonstrated that up-regulation of PTB expression significantly enhanced viral titer (t = 6.400, P < 0.01), whereas reducing PTB expression level weakened virus infectivity (t = 5.055, P < 0.01).

CONCLUSIONS

PTB positively interacts with the ZIKV 5'UTR and enhances IRES activity and virus production.

The Susceptibility of Chickens to Zika Virus: A Comprehensive Study on Age-Dependent Infection Dynamics and Host Responses

Zika virus (ZIKV) remains a public health concern, with epidemics in endemic regions and sporadic outbreaks in new areas posing significant threats. Several mosquito-borne flaviviruses that can cause human illness, including West Nile, Usutu, and St. Louis encephalitis, have associations with birds. However, the susceptibility of chickens to ZIKV and their role in viral epidemiology is not currently known. We investigated the susceptibility of chickens to experimental ZIKV infection using chickens ranging from 1-day-old chicks to 6-week-old birds. ZIKV caused no clinical signs in chickens of all age groups tested. Viral RNA was detected in the blood and tissues during the first 5 days post-inoculation in 1-day and 4-day-old chicks inoculated with a high viral dose, but ZIKV was undetectable in 6-week-old birds at all timepoints. Minimal antibody responses were observed in 6-week-old birds, and while present in younger chicks, they waned by 28 days post-infection. Innate immune responses varied significantly between age groups. Robust type I interferon and inflammasome responses were measured in older chickens, while limited innate immune activation was observed in younger chicks. Signal transducer and activator of transcription 2 (STAT2) is a major driver of host restriction to ZIKV, and chicken STAT2 is distinct from human STAT2, potentially contributing to the observed resistance to ZIKV infection. The rapid clearance of the virus in older chickens coincided with an effective innate immune response, highlighting age-dependent susceptibility. Our study indicates that chickens are not susceptible to productive ZIKV infection and are unlikely to play a role in the ZIKV epidemiology.

Design, development, and validation of multi-epitope proteins for serological diagnosis of Zika virus infections and discrimination from dengue virus seropositivity

Zika virus (ZIKV), an arbovirus from the Flaviviridae family, is the causative agent of Zika fever, a mild and frequent oligosymptomatic disease in humans. Nonetheless, on rare occasions, ZIKV infection can be associated with Guillain-Barré Syndrome (GBS), and severe congenital complications, such as microcephaly. The oligosymptomatic disease, however, presents symptoms that are quite similar to those observed in infections caused by other frequent co-circulating arboviruses, including dengue virus (DENV). Moreover, the antigenic similarity between ZIKV and DENV, and even with other members of the Flaviviridae family, complicates serological testing due to the high cross-reactivity of antibodies. Here, we designed, produced in a prokaryotic expression system, and purified three multiepitope proteins (ZIKV-1, ZIKV-2, and ZIKV-3) for differential diagnosis of Zika. The proteins were evaluated as antigens in ELISA tests for the detection of anti-ZIKV IgG using ZIKV- and DENV-positive human sera. The recombinant proteins were able to bind and detect anti-ZIKV antibodies without cross-reactivity with DENV-positive sera and showed no reactivity with Chikungunya virus (CHIKV)- positive sera. ZIKV-1, ZIKV-2, and ZIKV-3 proteins presented 81.6%, 95%, and 66% sensitivity and 97%, 96%, and 84% specificity, respectively. Our results demonstrate the potential of the designed and expressed antigens in the development of specific diagnostic tests for the detection of IgG antibodies against ZIKV, especially in regions with the circulation of multiple arboviruses.

Tropism and immune response of chikungunya and zika viruses: An overview

Zika virus (ZIKV) and chikungunya virus (CHIKV) are two medically important vector-borne viruses responsible for causing significant disease burden in humans, including neurological sequelae/complications. Besides sharing some common clinical features, ZIKV has major shares in causing microcephaly and brain malformations in developing foetus, whereas CHIKV causes chronic joint pain/swelling in infected individuals. Both viruses have a common route of entry to the host body. i.e., dermal site of inoculation through the bite of an infected mosquito and later taken up by different immune cells for further dissemination to other areas of the host body that lead to a range of immune responses via different pathways. The immune responses generated by both viruses have similar characteristics with varying degrees of inflammation and activation of immune cells. However, the overall response of immune cells is not fully explored in the context of ZIKV and CHIKV infection. The knowledge of cellular tropism and the immune response is the key to understanding the mechanisms of viral immunity and pathogenesis, which may allow to develop novel therapeutic strategies for these viral infections. This review aims to discuss recent advancements and identify the knowledge gaps in understanding the mechanism of cellular tropism and immune response of CHIKV and ZIKV.

Immunosensors-The Future of Pathogen Real-Time Detection

Pathogens and their toxins can cause various diseases of different severity. Some of them may be fatal, and therefore early diagnosis and suitable treatment is essential. There are numerous available methods used for their rapid screening. Conventional laboratory-based techniques such as culturing, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are dominant. However, culturing still remains the "gold standard" for their identification. These methods have many advantages, including high sensitivity and selectivity, but also numerous limitations, such as long experiment-time, costly instrumentation, and the need for well-qualified personnel to operate the equipment. All these existing limitations are the reasons for the continuous search for a new solutions in the field of bacteria identification. For years, research has been focusing on the use of immunosensors in various types of toxin- and pathogen-detection. Compared to the conventional methods, immunosensors do not require well-trained personnel. What is more, immunosensors are quick, highly selective and sensitive, and possess the potential to significantly improve the pathogen and toxin diagnostic-processes. There is a very important potential use for them in various transport systems, where the risk of contamination by bioagents is very high. In this paper, the advances in the field of immunosensor usage in pathogenic microorganism- and toxin-detection, are described.

Capeding M, Padilla CD, Sasmono RT, Hafalla JCR, Hibberd ML. Combining rapid diagnostic tests to estimate primary and post-primary dengue immune status at the point of care

BACKGROUND

Characterising dengue virus (DENV) infection history at the point of care is challenging as it relies on intensive laboratory techniques. We investigated how combining different rapid diagnostic tests (RDTs) can be used to accurately determine the primary and post-primary DENV immune status of reporting patients during diagnosis.

METHODS AND FINDINGS

Serum from cross-sectional surveys of acute suspected dengue patients in Indonesia (N:200) and Vietnam (N: 1,217) were assayed using dengue laboratory assays and RDTs. Using logistic regression modelling, we determined the probability of being DENV NS1, IgM and IgG RDT positive according to corresponding laboratory viremia, IgM and IgG ELISA metrics. Laboratory test thresholds for RDT positivity/negativity were calculated using Youden's J index and were utilized to estimate the RDT outcomes in patients from the Philippines, where only data for viremia, IgM and IgG were available (N:28,326). Lastly, the probabilities of being primary or post-primary according to every outcome using all RDTs, by day of fever, were calculated. Combining NS1, IgM and IgG RDTs captured 94.6% (52/55) and 95.4% (104/109) of laboratory-confirmed primary and post-primary DENV cases, respectively, during the first 5 days of fever. Laboratory test predicted, and actual, RDT outcomes had high agreement (79.5% (159/200)). Among patients from the Philippines, different combinations of estimated RDT outcomes were indicative of post-primary and primary immune status. Overall, IgG RDT positive results were confirmatory of post-primary infections. In contrast, IgG RDT negative results were suggestive of both primary and post-primary infections on days 1-2 of fever, yet were confirmatory of primary infections on days 3-5 of fever.

CONCLUSION

We demonstrate how the primary and post-primary DENV immune status of reporting patients can be estimated at the point of care by combining NS1, IgM and IgG RDTs and considering the days since symptoms onset. This framework has the potential to strengthen surveillance operations and dengue prognosis, particularly in low resource settings.

Antioxidant and antiviral activity of fullerol against Zika virus

Neglected for years, Zika virus (ZIKV) has become one of the most relevant arboviruses in current public health. The recent Zika fever epidemic in the Americas generated a worldwide alert due to the association with diseases such as Guillain-Barré syndrome and congenital syndromes. Among the pathogenesis of ZIKV, recent studies suggest that oxidative stress plays an important role during infection and that compounds capable of modulating oxidative stress are promising as therapeutics. Furthermore, so far there are no specific and efficient antiviral drug or vaccine available against ZIKV. Thus, fullerol was evaluated in the context of infection by ZIKV, since it is a carbon nanomaterial known for its potent antioxidant action. In this study, fullerol did not alter cell viability at the concentrations tested, proving to be inert, beyond to presenting high antioxidant power at low concentrations. ZIKV infection of human glioblastoma increased the production of reactive oxygen species by 60% and modulated the Nrf-2 pathway activity negatively. After treatment with fullerol, both conditions were restored to baseline levels. Additionally, fullerol was able to reduce viral production by up to 90%. Therefore, our results suggest that fullerol as a promising candidate in the control of ZIKV infections, presenting both antioxidant and antiviral action.

Electrochemical biosensors for neglected tropical diseases: A review

A group of infectious and parasitic diseases with prevalence in tropical and subtropical regions of the planet, especially in places with difficult access, internal conflicts, poverty, and low visibility from the government and health agencies are classified as neglected tropical diseases. While some well-intentioned isolated groups are making the difference on a global scale, the number of new cases and deaths is still alarming. The development and employment of low-cost, miniaturized, and easy-to-use devices as biosensors could be the key to fast diagnosis in such areas leading to a better treatment to further eradication of such diseases. Therefore, this review contains useful information regarding the development of such devices in the past ten years (2010-2020). Guided by the updated list from the World Health Organization, the work evaluated the new trends in the biosensor field applied to the early detection of neglected tropical diseases, the efficiencies of the devices compared to the traditional techniques, and the applicability on-site for local distribution. So, we focus on Malaria, Chagas, Leishmaniasis, Dengue, Zika, Chikungunya, Schistosomiasis, Leprosy, Human African trypanosomiasis (sleeping sickness), Lymphatic filariasis, and Rabies. Few papers were found concerning such diseases and there is no available commercial device in the market. The works contain information regarding the development of point-of-care devices, but there are only at proof of concepts stage so far. Details of electrode modification and construction of electrochemical biosensors were summarized in Tables. The demand for the eradication of neglected tropical diseases is increasing. The use of biosensors is pivotal for the cause, but appliable devices are scarce. The information present in this review can be useful for further development of biosensors in the hope of helping the world combat these deadly diseases.

Cerebral organoids to unravel the mechanisms underlying malformations of human cortical development

Genetic studies identified multiple mutations associated with malformations of cortical development (MCD) in humans. When analyzing the underlying mechanisms in non-human experimental models it became increasingly evident, that these mutations accumulate in genes, which functions evolutionary progressed from rodents to humans resulting in an incomplete reflection of the molecular and cellular alterations in these models. Human brain organoids derived from human pluripotent stem cells resemble early aspects of human brain development to a remarkable extent making them an attractive model to investigate MCD. Here we review how human brain organoids enable the generation of fundamental new insight about the underlying pathomechanisms of MCD. We show how phenotypic features of these diseases are reflected in human brain organoids and discuss challenges and future considerations but also limitations for the use of human brain organoids to model human brain development and associated disorders.