Displaying all 18 publications

Abstract:
Sort:
  1. Molecular phylogenetic and evolutionary analyses of Muar strain of Japanese encephalitis virus reveal it is the missing fifth genotype
    Mohammed MA, Galbraith SE, Radford AD, Dove W, Takasaki T, Kurane I, et al.
    Infect Genet Evol, 2011 Jul;11(5):855-62.
    PMID: 21352956 DOI: 10.1016/j.meegid.2011.01.020
    Japanese encephalitis virus (JEV) is the most important cause of epidemic encephalitis worldwide but its origin is unknown. Epidemics of encephalitis suggestive of Japanese encephalitis (JE) were described in Japan from the 1870s onwards. Four genotypes of JEV have been characterised and representatives of each genotype have been fully sequenced. Based on limited information, a single isolate from Malaysia is thought to represent a putative fifth genotype. We have determined the complete nucleotide and amino acid sequence of Muar strain and compared it with other fully sequenced JEV genomes. Muar was the least similar, with nucleotide divergence ranging from 20.2 to 21.2% and amino acid divergence ranging from 8.5 to 9.9%. Phylogenetic analysis of Muar strain revealed that it does represent a distinct fifth genotype of JEV. We elucidated Muar signature amino acids in the envelope (E) protein, including E327 Glu on the exposed lateral surface of the putative receptor binding domain which distinguishes Muar strain from the other four genotypes. Evolutionary analysis of full-length JEV genomes revealed that the mean evolutionary rate is 4.35 × 10(-4) (3.4906 × 10(-4) to 5.303 × 10(-4)) nucleotides substitutions per site per year and suggests JEV originated from its ancestral virus in the mid 1500s in the Indonesia-Malaysia region and evolved there into different genotypes, which then spread across Asia. No strong evidence for positive selection was found between JEV strains of the five genotypes and the E gene has generally been subjected to strong purifying selection.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  2. Molecular Docking and Molecular Dynamics Simulation Studies to Predict Flavonoid Binding on the Surface of DENV2 E Protein
    Ismail NA, Jusoh SA
    Interdiscip Sci, 2017 Dec;9(4):499-511.
    PMID: 26969331 DOI: 10.1007/s12539-016-0157-8
    Dengue infections are currently estimated to be 390 million cases annually. Yet, there is no vaccine or specific therapy available. Envelope glycoprotein E (E protein) of DENV mediates viral attachment and entry into the host cells. Several flavonoids have been shown to inhibit HIV-1 and hepatitis C virus entry during the virus-host membrane fusion. In this work, molecular docking method was employed to predict the binding of nine flavonoids (baicalin, baicalein, EGCG, fisetin, glabranine, hyperoside, ladanein, quercetin and flavone) to the soluble ectodomain of DENV type 2 (DENV2) E protein. Interestingly, eight flavonoids were found to dock into the same binding pocket located between the domain I and domain II of different subunits of E protein. Consistent docking results were observed not only for the E protein structures of the DENV2-Thai and DENV2-Malaysia (a homology model) but also for the E protein structures of tick-borne encephalitis virus and Japanese encephalitis virus. In addition, molecular dynamics simulations were performed to further evaluate the interaction profile of the docked E protein-flavonoid complexes. Ile4, Gly5, Asp98, Gly100 and Val151 residues of the DENV2-My E protein that aligned to the same residues in the DENV2-Thai E protein form consistent hydrogen bond interactions with baicalein, quercetin and EGCG during the simulations. This study demonstrates flavonoids potentially form interactions with the E protein of DENV2.
    Matched MeSH terms: Viral Envelope Proteins/metabolism*
  3. Fulltext Structural studies of Chikungunya virus maturation
    Yap ML, Klose T, Urakami A, Hasan SS, Akahata W, Rossmann MG
    Proc Natl Acad Sci U S A, 2017 12 26;114(52):13703-13707.
    PMID: 29203665 DOI: 10.1073/pnas.1713166114
    Cleavage of the alphavirus precursor glycoprotein p62 into the E2 and E3 glycoproteins before assembly with the nucleocapsid is the key to producing fusion-competent mature spikes on alphaviruses. Here we present a cryo-EM, 6.8-Å resolution structure of an "immature" Chikungunya virus in which the cleavage site has been mutated to inhibit proteolysis. The spikes in the immature virus have a larger radius and are less compact than in the mature virus. Furthermore, domains B on the E2 glycoproteins have less freedom of movement in the immature virus, keeping the fusion loops protected under domain B. In addition, the nucleocapsid of the immature virus is more compact than in the mature virus, protecting a conserved ribosome-binding site in the capsid protein from exposure. These differences suggest that the posttranslational processing of the spikes and nucleocapsid is necessary to produce infectious virus.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  4. Fulltext Identification of Peptide Inhibitors of Enveloped Viruses Using Support Vector Machine
    Xu Y, Yu S, Zou JW, Hu G, Rahman NA, Othman RB, et al.
    PLoS One, 2015;10(11):e0144171.
    PMID: 26636321 DOI: 10.1371/journal.pone.0144171
    The peptides derived from envelope proteins have been shown to inhibit the protein-protein interactions in the virus membrane fusion process and thus have a great potential to be developed into effective antiviral therapies. There are three types of envelope proteins each exhibiting distinct structure folds. Although the exact fusion mechanism remains elusive, it was suggested that the three classes of viral fusion proteins share a similar mechanism of membrane fusion. The common mechanism of action makes it possible to correlate the properties of self-derived peptide inhibitors with their activities. Here we developed a support vector machine model using sequence-based statistical scores of self-derived peptide inhibitors as input features to correlate with their activities. The model displayed 92% prediction accuracy with the Matthew's correlation coefficient of 0.84, obviously superior to those using physicochemical properties and amino acid decomposition as input. The predictive support vector machine model for self- derived peptides of envelope proteins would be useful in development of antiviral peptide inhibitors targeting the virus fusion process.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  5. Fulltext Secretion of N- and O-linked Glycoproteins from 4T1 Murine Mammary Carcinoma Cells
    Phang WM, Tan AA, Gopinath SC, Hashim OH, Kiew LV, Chen Y
    Int J Med Sci, 2016;13(5):330-9.
    PMID: 27226773 DOI: 10.7150/ijms.14341
    Breast cancer is one of the most common cancers that affect women globally and accounts for ~23% of all cancers diagnosed in women. Breast cancer is also one of the leading causes of death primarily due to late stage diagnoses and a lack of effective treatments. Therefore, discovering protein expression biomarkers is mandatory for early detection and thus, critical for successful therapy. Two-dimensional electrophoresis (2D-E) coupled with lectin-based analysis followed by mass spectrometry were applied to identify potential biomarkers in the secretions of a murine mammary carcinoma cell line. Comparisons of the protein profiles of the murine 4T1 mammary carcinoma cell line and a normal murine MM3MG mammary cell line indicated that cadherin-1 (CDH), collagenase 3 (MMP-13), Viral envelope protein G7e (VEP), Gag protein (GAG) and Hypothetical protein LOC433182 (LOC) were uniquely expressed by the 4T1 cells, and pigment epithelium-derived factor (PEDF) was exclusively secreted by the MM3MG cells. Further analysis by a lectin-based study revealed that aberrant O-glycosylated CDH, N-glycosylated MMP-13 and LOC were present in the 4T1 medium. These differentially expressed N- and O-linked glycoprotein candidates, which were identified by combining lectin-based analysis with 2D-E, could serve as potential diagnostic and prognostic markers for breast cancer.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  6. Dengue envelope domain III-peptide binding analysis via tryptophan fluorescence quenching assay
    Baharuddin A, Amir Hassan A, Othman R, Xu Y, Huang M, Ario Tejo B, et al.
    Chem Pharm Bull (Tokyo), 2014;62(10):947-55.
    PMID: 25273053
    In the efforts to find an anti-viral treatment for dengue, a simple tryptophan fluorescence-screening assay aimed at identifying dengue domain III envelope (EIII) protein inhibitors was developed. Residue Trp391 of EIII was used as an intrinsic probe to monitor the change in fluorescence of the tryptophan residue upon binding to a peptide. The analysis was based on the electron excitation at 280 nm and fluorescence emission at 300-400 nm of EIII, followed by quenching of fluorescence in the presence of potential peptidic inhibitors coded DS36wt, DS36opt, DN58wt and DN58opt. The present study found that the fluorescence of the recombinant EIII was quenched following the binding of DS36opt, DN58wt and DN58opt in a concentration-dependent manner. Since the λmax for emission remained unchanged, the effect was not due to a change in the environment of the tryptophan side chain. In contrast, a minimal fluorescence-quenching effect of DS36wt at 20 and 40 µM suggested that the DS36wt does not have any binding ability to EIII. This was supported by a simple native-page gel retardation assay that showed a band shift of EIII domain when incubated with DS36opt, DN58wt and DN58opt but not with DS36wt. We thus developed a low-cost and convenient spectrophotometric binding assay for the analysis of EIII-peptide interactions in a drug screening application.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  7. Fulltext Antiviral activity of silymarin and baicalein against dengue virus
    Low ZX, OuYong BM, Hassandarvish P, Poh CL, Ramanathan B
    Sci Rep, 2021 10 27;11(1):21221.
    PMID: 34707245 DOI: 10.1038/s41598-021-98949-y
    Dengue is an arthropod-borne viral disease that has become endemic and a global threat in many countries with no effective antiviral drug available currently. This study showed that flavonoids: silymarin and baicalein could inhibit the dengue virus in vitro and were well tolerated in Vero cells with a half-maximum cytotoxic concentration (CC50) of 749.70 µg/mL and 271.03 µg/mL, respectively. Silymarin and baicalein exerted virucidal effects against DENV-3, with a selective index (SI) of 10.87 and 21.34, respectively. Baicalein showed a better inhibition of intracellular DENV-3 progeny with a SI of 7.82 compared to silymarin. Baicalein effectively blocked DENV-3 attachment (95.59%) to the Vero cells, while silymarin prevented the viral entry (72.46%) into the cells, thus reducing viral infectivity. Both flavonoids showed promising antiviral activity against all four dengue serotypes. The in silico molecular docking showed that silymarin could bind to the viral envelope (E) protein with a binding affinity of - 8.5 kcal/mol and form hydrogen bonds with the amino acids GLN120, TRP229, ASN89, and THR223 of the E protein. Overall, this study showed that silymarin and baicalein exhibited potential anti-DENV activity and could serve as promising antiviral agents for further development against dengue infection.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  8. Fulltext A functional henipavirus envelope glycoprotein pseudotyped lentivirus assay system
    Khetawat D, Broder CC
    Virol J, 2010 Nov 12;7:312.
    PMID: 21073718 DOI: 10.1186/1743-422X-7-312
    BACKGROUND: Hendra virus (HeV) and Nipah virus (NiV) are newly emerged zoonotic paramyxoviruses discovered during outbreaks in Queensland, Australia in 1994 and peninsular Malaysia in 1998/9 respectively and classified within the new Henipavirus genus. Both viruses can infect a broad range of mammalian species causing severe and often-lethal disease in humans and animals, and repeated outbreaks continue to occur. Extensive laboratory studies on the host cell infection stage of HeV and NiV and the roles of their envelope glycoproteins have been hampered by their highly pathogenic nature and restriction to biosafety level-4 (BSL-4) containment. To circumvent this problem, we have developed a henipavirus envelope glycoprotein pseudotyped lentivirus assay system using either a luciferase gene or green fluorescent protein (GFP) gene encoding human immunodeficiency virus type-1 (HIV-1) genome in conjunction with the HeV and NiV fusion (F) and attachment (G) glycoproteins.

    RESULTS: Functional retrovirus particles pseudotyped with henipavirus F and G glycoproteins displayed proper target cell tropism and entry and infection was dependent on the presence of the HeV and NiV receptors ephrinB2 or B3 on target cells. The functional specificity of the assay was confirmed by the lack of reporter-gene signals when particles bearing either only the F or only G glycoprotein were prepared and assayed. Virus entry could be specifically blocked when infection was carried out in the presence of a fusion inhibiting C-terminal heptad (HR-2) peptide, a well-characterized, cross-reactive, neutralizing human mAb specific for the henipavirus G glycoprotein, and soluble ephrinB2 and B3 receptors. In addition, the utility of the assay was also demonstrated by an examination of the influence of the cytoplasmic tail of F in its fusion activity and incorporation into pseudotyped virus particles by generating and testing a panel of truncation mutants of NiV and HeV F.

    CONCLUSIONS: Together, these results demonstrate that a specific henipavirus entry assay has been developed using NiV or HeV F and G glycoprotein pseudotyped reporter-gene encoding retrovirus particles. This assay can be conducted safely under BSL-2 conditions and will be a useful tool for measuring henipavirus entry and studying F and G glycoprotein function in the context of virus entry, as well as in assaying and characterizing neutralizing antibodies and virus entry inhibitors.

    Matched MeSH terms: Viral Envelope Proteins/metabolism*
  9. Fulltext CPB1 of Aedes aegypti interacts with DENV2 E protein and regulates intracellular viral accumulation and release from midgut cells
    Tham HW, Balasubramaniam VR, Tejo BA, Ahmad H, Hassan SS
    Viruses, 2014 Dec;6(12):5028-46.
    PMID: 25521592 DOI: 10.3390/v6125028
    Aedes aegypti is a principal vector responsible for the transmission of dengue viruses (DENV). To date, vector control remains the key option for dengue disease management. To develop new vector control strategies, a more comprehensive understanding of the biological interactions between DENV and Ae. aegypti is required. In this study, a cDNA library derived from the midgut of female adult Ae. aegypti was used in yeast two-hybrid (Y2H) screenings against DENV2 envelope (E) protein. Among the many interacting proteins identified, carboxypeptidase B1 (CPB1) was selected, and its biological interaction with E protein in Ae. aegypti primary midgut cells was further validated. Our double immunofluorescent assay showed that CPB1-E interaction occurred in the endoplasmic reticulum (ER) of the Ae. aegypti primary midgut cells. Overexpression of CPB1 in mosquito cells resulted in intracellular DENV2 genomic RNA or virus particle accumulation, with a lower amount of virus release. Therefore, we postulated that in Ae. aegypti midgut cells, CPB1 binds to the E protein deposited on the ER intraluminal membranes and inhibits DENV2 RNA encapsulation, thus inhibiting budding from the ER, and may interfere with immature virus transportation to the trans-Golgi network.
    Matched MeSH terms: Viral Envelope Proteins/metabolism*
  10. Glycosylation and antigenic variation among Kunjin virus isolates
    Adams SC, Broom AK, Sammels LM, Hartnett AC, Howard MJ, Coelen RJ, et al.
    Virology, 1995 Jan 10;206(1):49-56.
    PMID: 7530394
    Previous studies have found Kunjin (KUN) virus isolates from within Australia to be genetically homogenous and that the envelope protein of the type strain (MRM61C) was unglycosylated and lacked a potential glycosylation site. We investigated the extent of antigenic variation between KUN virus isolates from Australia and Sarawak using an immunoperoxidase assay and a panel of six monoclonal antibodies. The glycosylation status of the E protein of each virus was also determined by N glycosidase F (PNGase F) digestion and limited sequence analysis. The results showed that KUN viruses isolated within Australia oscillated between three antigenic types defined by two epitopes whose expression was influenced by passage history and host cell type. In contrast an isolate from Sarawak formed a stable antigenic type that was not influenced by passage history and was distinct from all Australian isolates. PNGase F digestions of KUN isolates indicated that 19 of the 33 viruses possessed a glycosylated E protein. Nucleotide sequence of the 5' third of the E gene of selected KUN isolates revealed that a single base change in PNGase F sensitive strains changed the tripeptide N-Y-F (amino acids 154-156 of the published sequence) to the potential glycosylation site N-Y-S. Further analysis revealed that passage history also had a significant influence on glycosylation.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  11. Identification of a 48kDa tubulin or tubulin-like C6/36 mosquito cells protein that binds dengue virus 2 using mass spectrometry
    Chee HY, AbuBakar S
    Biochem Biophys Res Commun, 2004 Jul 16;320(1):11-7.
    PMID: 15207695
    Binding of dengue virus 2 (DENV-2) to C6/36 mosquito cells protein was investigated. A 48 kDa DENV-2-binding C6/36 cells protein (D2BP) was detected in a virus overlay protein-binding assay. The binding occurred only to the C6/36 cells cytosolic protein fraction and it was inhibited by free D2BP. D2BP was shown to bind to DENV-2 E in the far-Western-binding studies and using mass spectrometry (MS) and MS/MS, peptide masses of the D2BP that matched to beta-tubulin and alpha-tubulin chains were identified. These findings suggest that DENV-2 through DENV-2 E binds directly to a 48 kDa tubulin or tubulin-like protein of C6/36 mosquito cells.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  12. Fulltext The Conserved Molecular Determinants of Virulence in Dengue Virus
    Ahmad Z, Poh CL
    Int J Med Sci, 2019;16(3):355-365.
    PMID: 30911269 DOI: 10.7150/ijms.29938
    Dengue virus belongs to the Flaviviridae family which also includes viruses such as the Zika, West Nile and yellow fever virus. Dengue virus generally causes mild disease, however, more severe forms of the dengue virus infection, dengue haemorrhagic fever (DHF) and dengue haemorrhagic fever with shock syndrome (DSS) can also occur, resulting in multiple organ failure and even death, especially in children. The only dengue vaccine available in the market, CYD-TDV offers limited coverage for vaccinees from 9-45 years of age and is only recommended for individuals with prior dengue exposure. A number of mutations that were shown to attenuate virulence of dengue virus in vitro and/or in vivo have been identified in the literature. The mutations which fall within the conserved regions of all four dengue serotypes are discussed. This review hopes to provide information leading to the construction of a live attenuated dengue vaccine that is suitable for all ages, irrespective of the infecting dengue serotype and prior dengue exposure.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  13. Fulltext Virus-specific read-through codon preference affects infectivity of chimeric cucumber green mottle mosaic viruses displaying a dengue virus epitope
    Teoh PG, Ooi AS, AbuBakar S, Othman RY
    J Biomed Biotechnol, 2009;2009:781712.
    PMID: 19325913 DOI: 10.1155/2009/781712
    A Cucumber green mottle mosaic virus (CGMMV) was used to present a truncated dengue virus type 2 envelope (E) protein binding region from amino acids 379 to 423 (EB4). The EB4 gene was inserted at the terminal end of the CGMMV coat protein (CP) open reading frame (ORF). Read-through sequences of TMV or CGMMV, CAA-UAG-CAA-UUA, or AAA-UAG-CAA-UUA were, respectively, inserted in between the CP and the EB4 genes. The chimeric clones, pRT, pRG, and pCG+FSRTRE, were transcribed into full-length capped recombinant CGMMV transcripts. Only constructs with the wild-type CGMMV read-through sequence yielded infectious viruses following infection of host plant, muskmelon (Cucumis melo) leaves. The ratio of modified to unmodified CP for the read-through expression clone developed was also found to be approximately 1:1, higher than what has been previously reported. It was also observed that infectivity was not affected by differences in pI between the chimera and its wild counterpart. Analysis of recombinant viruses after 21-days-postinculation (dpi) revealed that deletions occurred resulting in partial reversions of the viral population to near wild type and suggesting that this would be the limiting harvest period for obtaining true to type recombinants with this construct.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  14. Fulltext Dengue virus type 2 envelope protein displayed as recombinant phage attachment protein reveals potential cell binding sites
    Abd-Jamil J, Cheah CY, AbuBakar S
    Protein Eng. Des. Sel., 2008 Oct;21(10):605-11.
    PMID: 18669522 DOI: 10.1093/protein/gzn041
    A method to map the specific site on dengue virus envelope protein (E) that interacts with cells and a neutralizing antibody is developed using serially truncated dengue virus type 2 (DENV-2) E displayed on M13 phages as recombinant E-g3p fusion proteins. Recombinant phages displaying the truncated E consisting of amino acids 297-423 (EB2) and amino acids 379-423 (EB4) were neutralized by DENV-2 patient sera and the DENV-2 E-specific 3H5-1 monoclonal antibodies suggesting that the phages retained the DENV-2 E antigenic properties. The EB4 followed by EB2 recombinant phages bound the most to human monocytes (THP-1), African green monkey kidney (Vero) cells, mosquito (C6/36) cells, ScFv specific against E and C6/36 cell proteins. Two potential cell attachment sites were mapped to loop I (amino acids 297 to 312) and loop II (amino acids 379-385) of the DENV-2 E using the phage-displayed truncated DENV-2 E fragments and by the analysis of the E structure. Loop II was present only in EB4 recombinant phages. There was no competition for binding to C6/36 cell proteins between EB2 and EB4 phages. Loop I and loop II are similar to the sub-complex specific and type-specific neutralizing monoclonal antibody binding sites, respectively. Hence, it is proposed that binding and entry of DENV involves the interaction of loop I to cell surface glycosaminoglycan-motif and a subsequent highly specific interaction involving loop II with other cell proteins. The phage displayed truncated DENV-2 E is a powerful and useful method for the direct determination of DENV-2 E cell binding sites.
    Matched MeSH terms: Viral Envelope Proteins/metabolism*
  15. Fulltext Antigenic cell associated dengue 2 virus proteins detected in vitro using dengue fever patients sera
    Abubakar S, Azila A, Suzana M, Chang LY
    Malays J Pathol, 2002 Jun;24(1):29-36.
    PMID: 16329553
    At least three major antigenic dengue 2 virus proteins were recognized by pooled dengue fever patients' sera in infected Aedes albopictus (C6/36) mosquito cells. Dengue virus envelope (E), premembrane (PrM) and non-structural protein 1 (NS 1) dimer were detected beginning on day 3 postinfection in both the cell membrane and cytosolic fractions. Using the patients' sera, the presence of antigenic intermediate core protein (C)-PrM and NS1-non-structural protein 2a (NS2a) in the cytoplasmic fraction of dengue 2 virus infected cells was revealed. The presence of a approximately 92 and approximately 84 kDa NS 1 dimer in the membrane (NS 1m) and cytosolic (NS 1c) fractions of C6/36 cells, respectively, was also recognized. Using individual patient's serum, it was further confirmed that all patients' sera contained antibodies that specifically recognized E, NS 1 and PrM present in the dengue 2 virus-infected cell membrane fractions, suggesting that these glycosylated virus proteins were the main antigenic proteins recognized in vivo. Detection of dengue 2 virus C antibody in some patients further suggested that C could be antigenic if presented in vivo.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  16. Combined detection and genotyping of Chikungunya virus by a specific reverse transcription-polymerase chain reaction
    Hasebe F, Parquet MC, Pandey BD, Mathenge EG, Morita K, Balasubramaniam V, et al.
    J Med Virol, 2002 Jul;67(3):370-4.
    PMID: 12116030
    A reverse transcription-polymerase chain reaction (RT-PCR) was developed for the detection of Chikungunya virus infection. Based on the nonstructural protein 1 (nsP1) and glycoprotein E1 (E1) genes of Chikungunya, two primer sets were designed. Total RNA were extracted from the cell culture fluid of Aedes albopictus C6/36 cells inoculated with the S27 prototype virus, isolated in Tanzania in 1953, and the Malaysian strains (MALh0198, MALh0298, and MALh0398), isolated in Malaysia in 1998. For both sets of RNA samples, the expected 354- and 294-base pair (bp) cDNA fragments were amplified effectively from the nsP1 and E1 genes, respectively. Phylogenetic analysis was conducted for the Malaysian strain and other virus strains isolated from different regions in the world endemic for Chikungunya, using partial E1 gene sequence data. The Malaysian strains isolated during the epidemics of 1998 fell into a cluster with other members of the Asian genotype.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
  17. Fulltext Geraniin extracted from the rind of Nephelium lappaceum binds to dengue virus type-2 envelope protein and inhibits early stage of virus replication
    Abdul Ahmad SA, Palanisamy UD, Tejo BA, Chew MF, Tham HW, Syed Hassan S
    Virol J, 2017 11 21;14(1):229.
    PMID: 29162124 DOI: 10.1186/s12985-017-0895-1
    BACKGROUND: The rapid rise and spread in dengue cases, together with the unavailability of safe vaccines and effective antiviral drugs, warrant the need to discover and develop novel anti-dengue treatments. In this study the antiviral activity of geraniin, extracted from the rind of Nephelium lappaceum, against dengue virus type-2 (DENV-2) was investigated.

    METHODS: Geraniin was prepared from Nephelium lappaceum rind by reverse phase C-18 column chromatography. Cytotoxicity of geraniin towards Vero cells was evaluated using MTT assay while IC50 value was determined by plaque reduction assay. The mode-of-action of geraniin was characterized using the virucidal, attachment, penetration and the time-of-addition assays'. Docking experiments with geraniin molecule and the DENV envelope (E) protein was also performed. Finally, recombinant E Domain III (rE-DIII) protein was produced to physiologically test the binding of geraniin to DENV-2 E-DIII protein, through ELISA competitive binding assay.

    RESULTS: Cytotoxicity assay confirmed that geraniin was not toxic to Vero cells, even at the highest concentration tested. The compound exhibited DENV-2 plaque formation inhibition, with an IC50 of 1.75 μM. We further revealed that geraniin reduced viral infectivity and inhibited DENV-2 from attaching to the cells but had little effect on its penetration. Geraniin was observed to be most effective when added at the early stage of DENV-2 infection. Docking experiments showed that geraniin binds to DENV E protein, specifically at the DIII region, while the ELISA competitive binding assay confirmed geraniin's interaction with rE-DIII with high affinity.

    CONCLUSIONS: Geraniin from the rind of Nephelium lappaceum has antiviral activity against DENV-2. It is postulated that the compound inhibits viral attachment by binding to the E-DIII protein and interferes with the initial cell-virus interaction. Our results demonstrate that geraniin has the potential to be developed into an effective antiviral treatment, particularly for early phase dengue viral infection.

    Matched MeSH terms: Viral Envelope Proteins/metabolism*
  18. Polysulfonate suramin inhibits Zika virus infection
    Tan CW, Sam IC, Chong WL, Lee VS, Chan YF
    Antiviral Res, 2017 07;143:186-194.
    PMID: 28457855 DOI: 10.1016/j.antiviral.2017.04.017
    Zika virus (ZIKV) is an arthropod-borne flavivirus that causes newborn microcephaly and Guillian-Barré syndrome in adults. No therapeutics are available to treat ZIKV infection or other flaviviruses. In this study, we explored the inhibitory effect of glycosaminoglycans and analogues against ZIKV infection. Highly sulfated heparin, dextran sulfate and suramin significantly inhibited ZIKV infection in Vero cells. De-sulfated heparin analogues lose inhibitory effect, implying that sulfonate groups are critical for viral inhibition. Suramin, an FDA-approved anti-parasitic drug, inhibits ZIKV infection with 3-5 log10 PFU viral reduction with IC50value of ∼2.5-5 μg/ml (1.93 μM-3.85 μM). A time-of-drug-addition study revealed that suramin remains potent even when administrated at 1-24 hpi. Suramin inhibits ZIKV infection by preventing viral adsorption, entry and replication. Molecular dynamics simulation revealed stronger interaction of suramin with ZIKV NS3 helicase than with the envelope protein. Suramin warrants further investigation as a potential antiviral candidate for ZIKV infection. Heparan sulfate (HS) is a cellular attachment receptor for multiple flaviviruses. However, no direct ZIKV-heparin interaction was observed in heparin-binding analysis, and downregulate or removal of cellular HS with sodium chlorate or heparinase I/III did not inhibit ZIKV infection. This indicates that cell surface HS is not utilized by ZIKV as an attachment receptor.
    Matched MeSH terms: Viral Envelope Proteins/metabolism
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links