Development of a high-throughput colorimetric Zika virus infection assay

A synthetic curcumin-like diarylpentanoid analog inhibits rhinovirus infection in H1 hela cells via multiple antiviral mechanisms

BACKGROUND

Rhinovirus (RV) infection is a major cause of common colds and asthma exacerbations, with no antiviral drug available. Curcumin exhibits broad-spectrum antiviral activities, but its therapeutic effect is limited by a poor pharmacokinetics profile. Curcumin-like diarylpentanoid analogs, particularly 2-benzoyl-6-(3,4-dihydroxybenzylidene)cyclohexen-1-ol (BDHBC) and 5-(3,4-dihydroxyphenyl)-3-hydroxy-1-(2-hydroxyphenyl)penta-2,4-dien-1-one (DHHPD), have better solubility and stability compared to curcumin.

OBJECTIVES

Therefore, this study aims to evaluate and compare the antiviral effects of curcumin, BDHBC, and DHHPD in an in vitro model of RV infection.

METHODS

The inhibitory effects on RV-16 infection in H1 HeLa cells were assessed using cytopathic effect (CPE) reduction assay, virus yield reduction assay, RT-qPCR, and Western blot. Antiviral effects in different modes of treatment (pre-, co-, and post-treatment) were also compared. Additionally, intercellular adhesion molecule 1 (ICAM-1) expression, RV binding, and infectivity were measured with Western blot, flow cytometry, and virucidal assay, respectively.

RESULTS

When used as a post-treatment, BDHBC (EC50: 4.19 µM; SI: 8.32) demonstrated stronger antiviral potential on RV-16 compared to DHHPD (EC50: 18.24 µM; SI: 1.82) and curcumin (less than 50% inhibition). BDHBC also showed the strongest inhibitory effect on RV-induced CPE, virus yield, vRNA, and viral proteins (P1, VP0, and VP2). Furthermore, BDHBC pre-treatment has a prophylactic effect against RV infection, which was attributed to reduced basal expression of ICAM-1. However, it did not affect virus binding, but exerted virucidal activity on RV-16, contributing to its antiviral effect during co-treatment.

CONCLUSION

BDHBC exhibits multiple antiviral mechanisms against RV infection and thus could be a potential antiviral agent for RV.

Evaluation of three alternative methods to the plaque reduction neutralizing assay for measuring neutralizing antibodies to dengue virus serotype 2

BACKGROUND

Dengue is a global public health challenge which requires accurate diagnostic methods for surveillance and control. The gold standard for detecting dengue neutralizing antibodies (nAbs) is the plaque reduction neutralization test (PRNT), which is both labor-intensive and time-consuming. This study aims to evaluate three alternative approaches, namely, the MTT-based (or (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) microneutralization assay, the xCELLigence real-time cell analysis (RTCA), and the immuno-plaque assay-focus reduction neutralization test (iPA-FRNT).

METHODS

Twenty-two residual serum samples were tested for DENV-2 nAbs using all four assays at three neutralization endpoints of 50%, 70% and 90% inhibition in virus growth. For each neutralization endpoint, results were compared using linear regression and correlation analyses. Test performance characteristics were further obtained for iPA-FRNT using 38 additional serum samples.

RESULTS

Positive correlation of DENV-2 neutralization titers for the MTT-based microneutralization assay and the PRNT assay was only observed at the neutralization endpoint of 50% (r = 0.690). In contrast, at all three neutralization end points, a linear trend and positive correlation of DENV-2 neutralization titers for the xCELLigence RTCA and the PRNT assays were observed, yielding strong or very strong correlation (r = 0.829 to 0.967). This was similarly observed for the iPA-FRNT assay (r = 0.821 to 0.916), which also offered the added advantage of measuring neutralizing titers to non-plaque forming viruses.

CONCLUSION

The xCELLigence RTCA and iPA-FRNT assays could serve as suitable alternatives to PRNT for dengue serological testing. The decision to adopt these methods may depend on the laboratory setting, and the utility of additional applications offered by these technologies.

In-Depth Characterization of Zika Virus Inhibitors Using Cell-Based Electrical Impedance

In this study, we use electric cell-substrate impedance sensing (ECIS), an established cell-based electrical impedance (CEI) technology, to decipher the kinetic cytopathic effect (CPE) induced by Zika virus (ZIKV) in susceptible human A549 lung epithelial cells and to evaluate several classes of compounds with reported antiviral activity (two entry inhibitors and two replication inhibitors). To validate the assay, we compare the results with those obtained with more traditional in vitro methods based on cell viability and viral yield readouts. We demonstrate that CEI can detect viral infection in a sensitive manner and can be used to determine antiviral potency. Moreover, CEI has multiple benefits compared to conventional assays: the technique is less laborious and better at visualizing the dynamic antiviral activity profile of the compounds, while also it has the ability to determine interesting time points that can be selected as endpoints in assays without continuous readout. We describe several parameters to characterize the compounds' cytotoxicity and their antiviral activity profile. In addition, the CEI patterns provide valuable additional information about the presumed mechanism of action of these compounds. Finally, as a proof of concept, we used CEI to evaluate the antiviral activity of a small series of compounds, for which we demonstrate that the sulfonated polymer PRO2000 inhibits ZIKV with a response profile representative for a viral entry inhibitor. Overall, we demonstrate for the first time that CEI is a powerful technology to evaluate and characterize compounds against ZIKV replication in a real-time, label-free, and noninvasive manner. IMPORTANCE Zika virus can cause serious disease in humans. Unfortunately, no antiviral drugs are available to treat infection. Here, we use an impedance-based method to continuously monitor virus infection in-and damage to-human cells. We can determine the Zika viral dose with this technique and also evaluate whether antiviral compounds protect the cells from damage caused by virus replication. We also show that this technique can be used to further unravel the characteristics of these compounds, such as their toxicity to the cells, and that it might even give further insight in their mechanism of antiviral action. Finally, we also find a novel Zika virus inhibitor, PRO2000. Overall, in this study, we use the impedance technology to-for the first time-evaluate compounds with anti-Zika virus properties, and therefore it can add valuable information in the further search for antiviral drugs.

Utilization of Aminoguanidine Prevents Cytotoxic Effects of Semen

Studies of human semen in cell or tissue culture are hampered by the high cytotoxic activity of this body fluid. The components responsible for the cell damaging activity of semen are amine oxidases, which convert abundant polyamines, such as spermine or spermidine in seminal plasma into toxic intermediates. Amine oxidases are naturally present at low concentrations in seminal plasma and at high concentrations in fetal calf serum, a commonly used cell culture supplement. Here, we show that, in the presence of fetal calf serum, seminal plasma, as well as the polyamines spermine and spermidine, are highly cytotoxic to immortalized cells, primary blood mononuclear cells, and vaginal tissue. Thus, experiments investigating the effect of polyamines and seminal plasma on cellular functions should be performed with great caution, considering the confounding cytotoxic effects. The addition of the amine oxidase inhibitor aminoguanidine to fetal calf serum and/or the utilization of serum-free medium greatly reduced this serum-induced cytotoxicity of polyamines and seminal plasma in cell lines, primary cells, and tissues and, thus, should be implemented in all future studies analyzing the role of polyamines and semen on cellular functions.

Immunodetection assays for the quantification of seasonal common cold coronaviruses OC43, NL63, or 229E infection confirm nirmatrelvir as broad coronavirus inhibitor

Besides pandemic SARS-CoV-2, also endemic seasonal human common cold coronaviruses (hCoVs) have a significant impact on human health and economy. Studies on hCoVs and the identification of antivirals are therefore crucial to improve human well-being. However, hCoVs have long been neglected and the methodology to study virus infection, replication and inhibition warrants being updated. We here evaluated the established plaque-based assays to determine viral titers and cell-to-cell spread and developed protocols for the immunodetection of the viral nucleocapsid protein by flow cytometry and in-cell ELISA to study infection rates at early time points. The developed protocols allow detection of hCoV-229E infection after 2, and hCoV-NL63 and -OC43 infection after 3 days at a single cell level or in a 96 well microtiter format, in large sample numbers without being laborious or expensive. Both assays can be applied to assess the susceptibility of cells to hCoV infection and replication, and to determine the efficacy of antiviral compounds as well as neutralizing antibodies in a sensitive and quantitative manner. Application revealed that clinically applied SARS-CoV-2 targeting monoclonal antibodies are inactive against hCoVs, but that the viral polymerase targeting antivirals remdesivir and molnupiravir are broadly active also against all three hCoVs. Further, the in-cell ELISA provided evidence that nirmatrelvir, previously shown to broadly inhibit coronavirus proteases, also prevents replication of authentic hCoVs. Importantly, the protocols described here can be easily adapted to other coronavirus strains and species as well as viruses of other families within a short time. This will facilitate future research on known and emerging (corona)viruses, support the identification of antivirals and increase the preparedness for future virus outbreaks.

A High-Throughput Yellow Fever Neutralization Assay

Quick and accurate detection of neutralizing antibodies (nAbs) against yellow fever is essential in serodiagnosis during outbreaks for surveillance and to evaluate vaccine efficacy in population-wide studies. All of this requires serological assays that can process a large number of samples in a highly standardized format. Albeit being laborious, time-consuming, and limited in throughput, the classical plaque reduction neutralization test (PRNT) is still considered the gold standard for the detection and quantification of nAbs due to its sensitivity and specificity. Here, we report the development of an alternative fluorescence-based serological assay (SNTFLUO) with an equally high sensitivity and specificity that is fit for high-throughput testing with the potential for automation. Finally, our novel SNTFLUO was cross-validated in several reference laboratories and against international WHO standards, showing its potential to be implemented in clinical use. SNTFLUO assays with similar performance are available for the Japanese encephalitis, Zika, and dengue viruses amenable to differential diagnostics. IMPORTANCE Fast and accurate detection of neutralizing antibodies (nAbs) against yellow fever virus (YFV) is key in yellow fever serodiagnosis, outbreak surveillance, and monitoring of vaccine efficacy. Although classical PRNT remains the gold standard for measuring YFV nAbs, this methodology suffers from inherent limitations such as low throughput and overall high labor intensity. We present a novel fluorescence-based serum neutralization test (SNTFLUO) with equally high sensitivity and specificity that is fit for processing a large number of samples in a highly standardized manner and has the potential to be implemented for clinical use. In addition, we present SNTFLUO assays with similar performance for Japanese encephalitis, Zika, and dengue viruses, opening new avenues for differential diagnostics.

Drug-Screening Strategies for Inhibition of Virus-Induced Neuronal Cell Death

A number of viruses, including Herpes Simplex Virus (HSV), West Nile Virus (WNV), La Crosse Virus (LACV), Zika virus (ZIKV) and Tick-borne encephalitis virus (TBEV), have the ability to gain access to the central nervous system (CNS) and cause severe neurological disease or death. Although encephalitis cases caused by these viruses are generally rare, there are relatively few treatment options available for patients with viral encephalitis other than palliative care. Many of these viruses directly infect neurons and can cause neuronal death. Thus, there is the need for the identification of useful therapeutic compounds that can inhibit virus replication in neurons or inhibit virus-induced neuronal cell death. In this paper, we describe the methodology to test compounds for their ability to inhibit virus-induced neuronal cell death. These protocols include the isolation and culturing of primary neurons; the culturing of neuroblastoma and neuronal stem cell lines; infection of these cells with viruses; treatment of these cells with selected drugs; measuring virus-induced cell death using MTT or XTT reagents; analysis of virus production from these cells; as well as the basic understanding in mode of action. We further show direct evidence of the effectiveness of these protocols by utilizing them to test the effectiveness of the polyphenol drug, Rottlerin, at inhibiting Zika virus infection and death of neuronal cell lines.

Identification of a Zika NS2B epitope as a biomarker for severe clinical phenotypes

The identification of specific biomarkers for Zika infection and its clinical complications is fundamental to mitigate the infection spread, which has been associated with a broad range of neurological sequelae. We present the characterization of antibody responses in serum samples from individuals infected with Zika, presenting non-severe (classical) and severe (neurological disease) phenotypes, with high-density peptide arrays comprising the Zika NS1 and NS2B proteins. The data pinpoints one strongly IgG-targeted NS2B epitope in non-severe infections, which is absent in Zika patients, where infection progressed to the severe phenotype. This differential IgG profile between the studied groups was confirmed by multivariate data analysis. Molecular dynamics simulations and circular dichroism have shown that the peptide in solution presents itself in a sub-optimal conformation for antibody recognition, which led us to computationally engineer an artificial protein able to stabilize the NS2B epitope structure. The engineered protein was used to interrogate paired samples from mothers and their babies presenting Zika-associated microcephaly and confirmed the absence of NS2B IgG response in those samples. These findings suggest that the assessment of antibody responses to the herein identified NS2B epitope is a strong candidate biomarker for the diagnosis and prognosis of Zika-associated neurological disease.

Recent progresses and remaining challenges for the detection of Zika virus

Zika virus (ZIKV) has emerged as a particularly notorious mosquito-borne flavivirus, which can lead to a devastating congenital syndrome in the fetuses of pregnant mothers (e.g., microcephaly, spasticity, craniofacial disproportion, miscarriage, and ocular abnormalities) and cause the autoimmune disorder Guillain-Barre' syndrome of adults. Due to its severity and rapid dispersal over several continents, ZIKV has been acknowledged to be a global health concern by the World Health Organization. Unfortunately, the ZIKV has recently resurged in India with the potential for devastating effects. Researchers from all around the world have worked tirelessly to develop effective detection strategies and vaccines for the prevention and control of ZIKV infection. In this review, we comprehensively summarize the most recent research into ZIKV, including the structural biology and evolution, historical overview, pathogenesis, symptoms, and transmission. We then focus on the detection strategies for ZIKV, including viral isolation, serological assays, molecular assays, sensing methods, reverse transcription loop mediated isothermal amplification, transcription-mediated amplification technology, reverse transcription strand invasion based amplification, bioplasmonic paper-based device, and reverse transcription isothermal recombinase polymerase amplification. To conclude, we examine the limitations of currently available strategies for the detection of ZIKV, and outline future opportunities and research challenges.

Assessment of replication of bovine herpesvirus type 4 in human glioblastoma and breast cancer cells as a potential oncolytic virus

Oncolytic viruses have been extensively used in cancer treatment due to their tropism, selective replication only in tumor cells, and possible synergic interaction with other therapeutics. Different researchers have demonstrated that bovine herpesvirus 4 (BoHV-4), a member of the gammaherpesviridae family, has oncolytic potential in some human-origin cancer cell lines like glioma through the selective replication strategy. Using four apoptosis detection methods, namely MTT, LDH, TUNEL, and Annexin V assays, we evaluated the apoptotic effect of BoHV-4 Movar33/63 reference strain along with a recombinant BoHV-4 expressing EGFP in U87 MG cells (human glioblastoma cell line), MDA MB-231 (human breast cancer cell line), and MCF10a (non-tumorigenic human mammary epithelial cell line). Our findings indicate that this virus can replicate and induce apoptosis in these cell lines and hinder in vitro proliferation in a dose-dependent manner. In conclusion, BoHV-4 has in vitro potential as a novel oncolytic virus in human cancer therapy. However, its replication potential in the MCF10a cells as a non-tumorigenic human mammary epithelial cell line is a concern in using this virus in cancer therapy, at least against human mammary tumors. Further studies must therefore be conducted to examine the specific apoptotic pathways induced by this virus to move on to further experiments.

An enzyme-based immunodetection assay to quantify SARS-CoV-2 infection

SARS-CoV-2 is a novel pandemic coronavirus that caused a global health and economic crisis. The development of efficient drugs and vaccines against COVID-19 requires detailed knowledge about SARS-CoV-2 biology. Several techniques to detect SARS-CoV-2 infection have been established, mainly based on counting infected cells by staining plaques or foci, or by quantifying the viral genome by PCR. These methods are laborious, time-consuming and expensive and therefore not suitable for a high sample throughput or rapid diagnostics. We here report a novel enzyme-based immunodetection assay that directly quantifies the amount of de novo synthesized viral spike protein within fixed and permeabilized cells. This in-cell ELISA enables a rapid and quantitative detection of SARS-CoV-2 infection in microtiter format, regardless of the virus isolate or target cell culture. It follows the established method of performing ELISA assays and does not require expensive instrumentation. Utilization of the in-cell ELISA allows to e.g. determine TCID₅₀ of virus stocks, antiviral efficiencies (IC₅₀ values) of drugs or neutralizing activity of sera. Thus, the in-cell spike ELISA represents a promising alternative to study SARS-CoV-2 infection and inhibition and may facilitate future research.

High-Throughput Zika Viral Titer Assay for Rapid Screening of Antiviral Drugs

Zika virus has recently emerged as a worldwide pathogen and public health burden due to its rapid spread and identification as a causative agent for multiple neurological defects, including congenital microcephaly. While there has been a flurry of recent research to address this emerging pathogen, there are currently no approved drug treatments for ZIKV infection. The gold standard for testing antiviral activity is to quantify infectious virion production. However, current infectious viral production assays, such as the plaque-forming or focus-forming unit assay, are tedious and labor intensive with a low-screening throughput. To facilitate drug development, we developed a Zika viral titration assay using an automated imaging system and an image analysis algorithm for viral colony quantification. This assay retained the principle of the classical virus titer assay, while improving workflow and offering higher screening throughput. In addition, this assay can be broadly adapted to quantification of other viruses.

[A non-coated enzyme-linked immunosorbent assay for screening zika virus envelope protein]

OBJECTIVE

To establish a non-coated enzyme-linked immunosorbent assay (ELISA) based on zika virus envelope (E) protein for detecting the expression of E protein in infected cells.

METHODS

Adherent Vero-143 cells infected with zika virus in a 96-well plate were fixed, and the antibodies against zika virus E protein were added at an optimized concentration to establish the non-coated ELISA method for E protein. The antiviral activities of lignans compound C1 was evaluated using this method. The accuracy of this non-coated ELISA was verified by RT-PCR, and the cross reaction with dengue virus was assessed.

RESULTS

After optimization, the background absorbance at 450 nm of uninfected cells was reduced to about 0.20. The antiviral activities of lignans compound C1 detected by this method were basically consistent with the results of RT-PCR. No cross reaction with dengue virus was found in this assay.

CONCLUSIONS

A non- coated ELISA method based on zika virus E protein was established, which can be used for screening antiviral agents against zika virus.

Combination of ELISA screening and seroneutralisation tests to expedite Zika virus seroprevalence studies

Here we propose a strategy allowing implementing efficient and practicable large-scale seroepidemiological studies for Zika Virus (ZIKV). It combines screening by a commercial NS1 protein-based Zika IgG ELISA, and confirmation by a cytopathic effect-based virus neutralization test (CPE-based VNT). In post-epidemic samples from Martinique Island blood donors (a population with a dengue seroprevalence above 90%), this strategy allowed reaching specificity and sensitivity values over 98%. The CPE-based VNT consists of recording CPE directly under the optical microscope, which is easy to identify with ZIKV strain H/PF/2013 at day 5 pi. Overall, considered that CPE-based VNT is cost effective and widely automatable, the NS1 protein-based Zika IgG ELISA+CPE-based VNT combination strategy represents a convenient tool to expedite ZIKV seroprevalence studies.

Research Models and Tools for the Identification of Antivirals and Therapeutics against Zika Virus Infection

Zika virus recently re-emerged and caused global outbreaks mainly in Central Africa, Southeast Asia, the Pacific Islands and in Central and South America. Even though there is a declining trend, the virus continues to spread throughout different geographical regions of the world. Since its re-emergence in 2015, massive advances have been made regarding our understanding of clinical manifestations, epidemiology, genetic diversity, genomic structure and potential therapeutic intervention strategies. Nevertheless, treatment remains a challenge as there is no licensed effective therapy available. This review focuses on the recent advances regarding research models, as well as available experimental tools that can be used for the identification and characterization of potential antiviral targets and therapeutic intervention strategies.

Kaposi's Sarcoma-Associated Herpesvirus Latency Locus Renders B Cells Hyperresponsive to Secondary Infections

Kaposi's sarcoma-associated herpesvirus (KSHV) induces B cell hyperplasia and neoplasia, such as multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL). To explore KSHV-induced B cell reprogramming in vivo, we expressed the KSHV latency locus, inclusive of all viral microRNAs (miRNAs), in B cells of transgenic mice in the absence of the inhibitory FcγRIIB receptor. The BALB/c strain was chosen as this is the preferred model to study B cell differentiation. The mice developed hyperglobulinemia, plasmacytosis, and B lymphoid hyperplasia. This phenotype was ameliorated by everolimus, which is a rapamycin derivative used for the treatment of mantle cell lymphoma. KSHV latency mice exhibited hyperresponsiveness to the T-dependent (TD) antigen mimic anti-CD40 and increased incidence of pristane-induced inflammation. Lastly, the adaptive immunity against a secondary infection with Zika virus (ZIKV) was markedly enhanced. These phenotypes are consistent with KSHV lowering the activation threshold of latently infected B cells, which may be beneficial in areas of endemicity, where KSHV is acquired in childhood and infections are common.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latency in B cells and is stringently linked to primary effusion lymphoma (PEL) and the premalignant B cell hyperplasia multicentric Castleman's disease (MCD). To investigate potential genetic background effects, we expressed the KSHV miRNAs in BALB/c transgenic mice. BALB/c mice are the preferred strain for B cell hybridoma development because of their propensity to develop predictable B cell responses to antigen. The BALB/c latency mice exhibited a higher incidence of B cell hyperplasia as well as sustained hyperglobulinemia. The development of neutralizing antibodies against ZIKV was augmented in BALB/c latency mice. Hyperglobulinemia was dampened by everolimus, a derivative of rapamycin, suggesting a role for mTOR inhibitors in managing immune activation, which is hallmark of KSHV infection as well as HIV infection.

A direct high-throughput in Cell-ELISA for measuring infectivity of cytopathic and non-cytopathic bovine viral diarrhoea virus strains applied to the assessment of antiviral activity

Low-cost high-throughput methods applicable to any virus strain are required for screening antiviral compounds against multiple field strains. Colorimetric cell-viability assays are used for this purpose as long as the viruses are cytopathic (CP) in cell culture. However, bovine viral diarrhoea virus (BVDV) strains circulating in the field are mostly non-cytopathic (NCP). An In Cell-ELISA aimed to measure viral infectivity by detecting a conserved protein produced during viral replication (non-structural protein 3, "NS3") was developed. The ELISA is performed without harvesting the cells, directly on the 96-wells culture plate. NS3 In Cell-ELISA was tested for its ability to assess BVDV-specific antiviral activity of recombinant bovine type I and III IFNs. Results correlated to those measured by qRT-PCR and virus titration. NS3 In Cell-ELISA was also efficient in estimating the IC50 of two compounds with different antiviral activity. Estimation of the 50% inhibition dose of each IFN using six BVDV strains of different biotype and genotype showed that CP strains were more susceptible to both IFNs than NCP, while type 2 NCP viruses were more sensitive to IFN-I. The In Cell-ELISA format using a detector antibody against a conserved non-structural protein can be potentially applied to accurately measure infectivity of any viral strain.

Low Zika virus seroprevalence among pregnant women in North Central Nigeria, 2016

BACKGROUND

Zika virus (ZIKV) has been known for decades in Africa but contemporary data is lacking at large.

OBJECTIVES

To describe the seroepidemiology of ZIKV in North Central Nigeria.

STUDY DESIGN

We performed a cross-sectional study at six health care facilities in North Central Nigeria from January to December 2016. Detection of ZIKV antibodies was done using an anti-ZIKV recombinant non-structural protein 1 (NS1)-based ELISA. A colorimetric assay to detect ZIKV neutralizing antibodies was used on ELISA reactive and randomly selected ELISA non-reactive samples. ZIKV real-time RT-PCR was done on a subset of samples.

RESULTS

A total of 468 individual samples were included with almost 60% from pregnant women. Using NS1-based ELISA, an anti-ZIKV positive rate of 6% for IgM and 4% for IgG was found. Pregnant women showed anti-ZIKV positive rates of 4% for IgM and 3% for IgG. None of the ZIKV antibody positive samples tested ZIKV RT-PCR positive. An association with male sex was found for anti-ZIKV IgG ELISA positivity (prevalence ratio 3.49; 95% confidence interval: 1.48-8.25; p = .004). No association with pregnancy, yellow fever vaccination or malaria was found for anti-ZIKV IgM or IgG positivity. ZIKV neutralizing antibodies were detected in 17/18 (94%) anti-ZIKV NS1 positive/borderline samples and in one sample without detectable ZIKV NS1 antibodies. Partial ZIKV E gene sequence was retrieved in one sample without ZIKV antibodies, which clustered within the West African ZIKV lineage.

CONCLUSIONS

Our results show a largely ZIKV immunologically naïve population and reinforce the importance of ZIKV surveillance in Africa.

The molecular tweezer CLR01 inhibits Ebola and Zika virus infection

Ebola (EBOV) and Zika viruses (ZIKV) are responsible for recent global health threats. As no preventive vaccines or antiviral drugs against these two re-emerging pathogens are available, we evaluated whether the molecular tweezer CLR01 may inhibit EBOV and ZIKV infection. This small molecule has previously been shown to inactivate HIV-1 and herpes viruses through a selective interaction with lipid-raft-rich regions in the viral envelope, which results in membrane disruption and loss of infectivity. We found that CLR01 indeed blocked infection of EBOV and ZIKV in a dose-dependent manner. The tweezer inhibited infection of epidemic ZIKV strains in cells derived from the anogenital tract and the central nervous system, and remained antivirally active in the presence of semen, saliva, urine and cerebrospinal fluid. Our findings show that CLR01 is a broad-spectrum inhibitor of enveloped viruses with prospects as a preventative microbicide or antiviral agent.

Development and evaluation of a novel high-throughput image-based fluorescent neutralization test for detection of Zika virus infection

Zika virus (ZIKV) is an emerging arbovirus belonging to the genus flavivirus that comprises other important public health viruses, such as dengue (DENV) and yellow fever (YFV). In general, ZIKV infection is a self-limiting disease, however cases of Guillain-Barré syndrome and congenital brain abnormalities in newborn infants have been reported. Diagnosing ZIKV infection remains a challenge, as viral RNA detection is only applicable until a few days after the onset of symptoms. After that, serological tests must be applied, and, as expected, high cross-reactivity between ZIKV and other flavivirus serology is observed. Plaque reduction neutralization test (PRNT) is indicated to confirm positive samples for being more specific, however it is laborious intensive and time consuming, representing a major bottleneck for patient diagnosis. To overcome this limitation, we developed a high-throughput image-based fluorescent neutralization test for ZIKV infection by serological detection. Using 226 human specimens, we showed that the new test presented higher throughput than traditional PRNT, maintaining the correlation between results. Furthermore, when tested with dengue virus samples, it showed 50.53% less cross reactivity than MAC-ELISA. This fluorescent neutralization test could be used for clinical diagnosis confirmation of ZIKV infection, as well as for vaccine clinical trials and seroprevalence studies.

The antimalarial drug amodiaquine possesses anti-ZIKA virus activities

Zika virus (ZIKV) outbreak has emerged as a global health threat, particularly in tropical areas, over the past few years. No antiviral therapy or vaccine is available at present. For these reasons, repurposing clinically approved drugs against ZIKV infection may provide rapid and cost-effective global health benefits. Here, we explored this strategy and screened eight FDA-approved drugs for antiviral activity against ZIKV using a cell-based assay. Our results show that the antimalarial drug amodiaquine has anti-ZIKV activity with EC₅₀ at low micromolar concentrations in cell culture. We further characterized amodiaquine antiviral activity against ZIKV and found that it targets early events of the viral replication cycle. Altogether, our results suggest that amodiaquine may be efficacious for the treatment of ZIKV infection.

Advances in Diagnosis, Surveillance, and Monitoring of Zika Virus: An Update

Zika virus (ZIKV) is associated with numerous human health-related disorders, including fetal microcephaly, neurological signs, and autoimmune disorders such as Guillain-Barré syndrome (GBS). Perceiving the ZIKA associated losses, in 2016, the World Health Organization (WHO) declared it as a global public health emergency. In consequence, an upsurge in the research on ZIKV was seen around the globe, with significant attainments over developing several effective diagnostics, drugs, therapies, and vaccines countering this life-threatening virus at an early step. State-of-art tools developed led the researchers to explore virus at the molecular level, and in-depth epidemiological investigations to understand the reason for increased pathogenicity and different clinical manifestations. These days, ZIKV infection is diagnosed based on clinical manifestations, along with serological and molecular detection tools. As, isolation of ZIKV is a tedious task; molecular assays such as reverse transcription-polymerase chain reaction (RT-PCR), real-time qRT-PCR, loop-mediated isothermal amplification (LAMP), lateral flow assays (LFAs), biosensors, nucleic acid sequence-based amplification (NASBA) tests, strand invasion-based amplification tests and immune assays like enzyme-linked immunosorbent assay (ELISA) are in-use to ascertain the ZIKV infection or Zika fever. Herein, this review highlights the recent advances in the diagnosis, surveillance, and monitoring of ZIKV. These new insights gained from the recent advances can aid in the rapid and definitive detection of this virus and/or Zika fever. The summarized information will aid the strategies to design and adopt effective prevention and control strategies to counter this viral pathogen of great public health concern.

Macromolecular Antiviral Agents against Zika, Ebola, SARS, and Other Pathogenic Viruses

Viral pathogens continue to constitute a heavy burden on healthcare and socioeconomic systems. Efforts to create antiviral drugs repeatedly lag behind the advent of pathogens and growing understanding is that broad‐spectrum antiviral agents will make strongest impact in future antiviral efforts. This work performs selection of synthetic polymers as novel broadly active agents and demonstrates activity of these polymers against Zika, Ebola, Lassa, Lyssa, Rabies, Marburg, Ebola, influenza, herpes simplex, and human immunodeficiency viruses. Results presented herein offer structure–activity relationships for these pathogens in terms of their susceptibility to inhibition by polymers, and for polymers in terms of their anionic charge and hydrophobicity that make up broad‐spectrum antiviral agents. The identified leads cannot be predicted based on prior data on polymer‐based antivirals and represent promising candidates for further development as preventive microbicides.

Compensating for cross-reactions using avidity and computation in a suspension multiplex immunoassay for serotyping of Zika versus other flavivirus infections

The recent spread of Zika virus (ZIKV) in the Americas and Asia necessitates an increased preparedness for improved maternal and perinatal health and blood safety. However, serological cross-reactions, especially to Dengue virus (DENV), complicate ZIKV antibody serodiagnosis. A novel “pan-Flavi” suspension multiplex immunoassay (PFSMIA) using 25 antigens, whole virus (WV), non-structural protein 1 (NS1), and envelope (E) proteins, from 7 zoonotic flaviviruses for specific detection of ZIKV and DENV IgM and IgG was developed. Patterns of antibody cross-reactivity, avidity, and kinetics were established in 104 sera from returning travelers with known ZIKV and DENV infections. PFSMIA gave IgM- and IgG-sensitivities for both viruses of 96–100%, compared to an immunofluorescence assay. Main IgM cross-reactions were to NS1, for IgG to the E and WV antigens. Infecting virus yielded reactivity to several antigens of the homologous virus, while cross-reactions tended to occur only to a single antigen from heterologous virus(es). A specificity-enhancing computer procedure took into account antibody isotype, number of antibody-reactive antigens per virus, avidity, average degree of cross-reactivity to heterologous flavivirus antigens, and reactivity changes in serial sera. It classified all 50 cases correctly. Applied to sera from 200 pregnant women and 173 blood donors from Sweden, one blood donor was found ZIKV NS1 IgM positive, and another as ZIKV NS1 IgG positive. These samples did not react with other ZIKV antigens and were thereby judged as false-positives. PFSMIA provided sensitive and specific ZIKV and DENV serology, warranting high-throughput serological surveillance and a minimized need for laborious and expensive virus neutralization assays.

A peptide-based viral inactivator inhibits Zika virus infection in pregnant mice and fetuses

Zika virus (ZIKV), a re-emerging flavivirus associated with neurological disorders, has spread rapidly to more than 70 countries and territories. However, no specific vaccines or antiviral drugs are currently available to prevent or treat ZIKV infection. Here we report that a synthetic peptide derived from the stem region of ZIKV envelope protein, designated Z2, potently inhibits infection of ZIKV and other flaviviruses in vitro. We show that Z2 interacts with ZIKV surface protein and disrupts the integrity of the viral membrane. Z2 can penetrate the placental barrier to enter fetal tissues and is safe for use in pregnant mice. Intraperitoneal administration of Z2 inhibits vertical transmission of ZIKV in pregnant C57BL/6 mice and protects type I or type I/II interferon receptor-deficient mice against lethal ZIKV challenge. Thus, Z2 has potential to be further developed as an antiviral treatment against ZIKV infection in high-risk populations, particularly pregnant women.

Zika virus (ZIKV) has spread rapidly in recent years and there is a need for antiviral treatments. Here, the authors develop an antiviral peptide, based on the stem region of ZIKV envelope protein, and show that it is safe in pregnant mice and inhibits ZIKV infection in pregnant mice and fetuses.