Displaying publications 1 - 20 of 104 in total

Abstract:
Sort:
  1. Japanese encephalitis virus disrupts blood-brain barrier and modulates apoptosis proteins in THBMEC cells
    Al-Obaidi MMJ, Bahadoran A, Har LS, Mui WS, Rajarajeswaran J, Zandi K, et al.
    Virus Res, 2017 04 02;233:17-28.
    PMID: 28279803 DOI: 10.1016/j.virusres.2017.02.012
    Japanese encephalitis (JE) is a neurotropic flavivirus that causes inflammation in central nervous system (CNS), neuronal death and also compromises the structural and functional integrity of the blood-brain barrier (BBB). The aim of this study was to evaluate the BBB disruption and apoptotic process in Japanese encephalitis virus (JEV)-infected transfected human brain microvascular endothelial cells (THBMECs). THBMECs were overlaid by JEV with different MOIs (0.5, 1.0, 5.0 and 10.0) and monitored by electrical cell-substrate impedance sensing (ECIS) in a real-time manner in order to observe the barrier function of THBMECs. Additionally, the level of 43 apoptotic proteins was quantified in the virally infected cells with different MOIs at 24h post infection. Infection of THBMEC with JEV induced an acute reduction in transendothelial electrical resistance (TEER) after viral infection. Also, significant up-regulation of Bax, BID, Fas and Fasl and down-regulation of IGFBP-2, BID, p27 and p53 were observed in JEV infected THBMECs with 0.5 and 10 MOIs compared to uninfected cells. Hence, the permeability of THBMECs is compromised during the JEV infection. In addition high viral load of the virus has the potential to subvert the host cell apoptosis to optimize the course of viral infection through deactivation of pro-apoptotic proteins.
  2. Surveillance of adult Aedes mosquitoes in Selangor, Malaysia
    Lau SM, Vythilingam I, Doss JI, Sekaran SD, Chua TH, Wan Sulaiman WY, et al.
    Trop Med Int Health, 2015 Oct;20(10):1271-80.
    PMID: 26094839 DOI: 10.1111/tmi.12555
    To determine the effectiveness of using sticky traps and the NS1 dengue antigen kit for the surveillance of Aedes mosquitoes for dengue control.
  3. Fulltext Cloning, expression and protective capacity of 37 kDa outer membrane protein gene (ompH) of Pasteurella multocida serotype B:2
    Tan HY, Nagoor NH, Sekaran SD
    Trop Biomed, 2010 Dec;27(3):430-41.
    PMID: 21399583 MyJurnal
    The major outer membrane protein (OmpH) of 4 local Malaysian strains of Pasteurella multocida serotype B:2 were characterized in comparison to ATCC strains. Three major peptide bands of MW 26, 32 and 37 kDa were characterized using SDSPAGE. Two of these fragments, the 32 kDa and 37 kDa were observed to be more reactive with a mouse polyclonal antiserum in all of the local isolates as well as the ATCC strains in a Western blot. However, the 32 kDa fragment was found to cross react with other Gram negative bacteria. Therefore, the 37 kDa OmpH was selected as vaccine candidate. The 37 kDa ompH gene of the isolated strain 1710 was cloned into an Escherichia coli expression vector to produce large amounts of recombinant OmpH (rOmpH). The 37 kDa ompH gene of strain 1710 was sequenced. In comparison to a reference strain X-73 of the ompH of P. multocida, 39bp was found deleted in the 37 kDa ompH gene. However, the deletion did not shift the reading frame or change the amino acid sequence. The rOmpH was used in a mice protection study. Mice immunized and challenged intraperitoneally resulted 100% protection against P. multocida whilst mice immunized subcutaneously and challenged intraperitoneally only resulted 80% protection. The rOmpH is therefore a suitable candidate for vaccination field studies. The same rOmpH was also used to develop a potential diagnostic kit in an ELISA format.
  4. Fulltext The detection and characterization of pathogenic Leptospira and the use of OMPs as potential antigens and immunogens
    Gebriel AM, Subramaniam G, Sekaran SD
    Trop Biomed, 2006 Dec;23(2):194-207.
    PMID: 17322822 MyJurnal
    The detection of leptospires in patient blood in the first week of the disease using PCR provides an early diagnostic tool. PCR using two sets of primers (G1/G2 and B64-I/B64-II) tested with samples seeded with 23 leptospiral strains from pathogenic and non-pathogenic strains was able to amplify leptospiral DNA from pathogenic strains only. Of the 39 antibody negative samples collected from patients suspected for leptospirosis, only 1 sample (2.6%) was PCR positive. Using LSSP-PCR, the G2 primers allowed the characterization of Leptopira species to 10 different genetic signatures which may have epidemiological value in determining species involved in outbreaks. Leptospiral outer membrane proteins from three strains were purified and reacted against patients sera and gave rise to different profiles for pathogenic and non-pathogenic strains. Lymphocytes of mice injected with OMPs proliferated and released IFN(-3) when stimulated in vitro using Leptospira OMP as antigens. This suggests that an immune response could be established using leptospiral OMPs as a putative vaccine. OMPs were also used in a Dot-ELISA to detect antibodies against Leptospira pathogens in humans.
  5. Evaluation of bactericidal and virucidal activity of novel disinfectant Aaride AGT-1 compared to other commercially available disinfectants against hospital-acquired infections (HAIs)
    Jindal HM, Chandramathi S, Sekaran SD, Suresh K
    Trop Biomed, 2020 Sep 01;37(3):626-636.
    PMID: 33612777 DOI: 10.47665/tb.37.3.626
    Hand hygiene is the topmost crucial procedure to prevent hospital-acquired infections. Choosing an effective hand disinfectant is necessary in enforcing good hand hygiene practice especially in hospital settings. The aim of the study was to investigate the efficacy of Aaride AGT-1 as a hand disinfectant for the inhibition of pathogenic microorganisms' transmission among both patients and personnel in the health care system compared to other commercially available disinfectants. In the present study, a new hand disinfectant Aaride AGT-1 was tested against several bacterial and viral pathogens to evaluate its antimicrobial activity profile. The results revealed that Aaride AGT-1 displayed the highest antibacterial activity against five pathogenic bacteria including MRSA when compared to other commercially available hand sanitizers. Aaride AGT-1 showed the lowest percentage needed to inhibit the growth of bacterial pathogens. In addition, results obtained from time killing assay revealed that Aaride AGT-1 demonstrated the best killing kinetics, by eradicating the bacterial cells rapidly within 0.5 min with 6 log reduction (>99.99% killing). Also, Aaride AGT1 was able to reduce 100% plaque formed by three viruses namely HSV-1, HSV-2 and EV-71. In conclusion, Aaride AGT-1 is capable of killing wide-spectrum of pathogens including bacteria and viruses compared to other common disinfectants used in hospital settings. Aaride AGT-1's ability to kill both bacteria and viruses contributes as valuable addition to the hand disinfection portfolio.
  6. Zika virus modulates blood-brain barrier of brain microvascular endothelial cells
    Ismail AA, Mahboob T, Samudi Raju C, Sekaran SD
    Trop Biomed, 2019 Dec 01;36(4):888-897.
    PMID: 33597462
    Zika virus (ZIKV) is a mosquito-borne Flaviviruses. ZIKV is known to cause birth defect in pregnant women, especially microcephaly in the fetus. Hence, more study is required to understand the infection of Zika virus towards human brain microvascular endothelial cells (MECs). In this study, brain MECs were infected with ZIKV at MOI of 1 and 5 in vitro. The changes in barrier function and membrane permeability of ZIKV-infected brain MECs were determined using electric cell-substrate impedance sensing (ECIS) system followed by gene expression of ZIKV-infected brain MECs at 24 hours post infection using one-color gene expression microarray. The ECIS results demonstrated that ZIKV infection enhances vascular leakage by increasing cell membrane permeability via alteration of brain MECs barrier function. This was further supported by high expression of proinflammatory cytokine genes (lnc-IL6-2, TNFAIP1 and TNFAIP6), adhesion molecules (CERCAM and ESAM) and growth factor (FIGF). Overall, findings of this study revealed that ZIKV infection could alter the barrier function of brain MECs by altering adhesion molecules and inflammatory response.
  7. The Cytokines CXCL10 and CCL2 and the Kynurenine Metabolite Anthranilic Acid Accurately Predict Patients at Risk of Developing Dengue With Warning Signs
    Jusof FF, Lim CK, Aziz FN, Soe HJ, Raju CS, Sekaran SD, et al.
    J Infect Dis, 2022 Nov 28;226(11):1964-1973.
    PMID: 35767283 DOI: 10.1093/infdis/jiac273
    BACKGROUND: The resolution or aggravation of dengue infection depends on the patient's immune response during the critical phase. Cytokines released by immune cells increase with the worsening severity of dengue infections. Cytokines activate the kynurenine pathway (KP) and the extent of KP activation then influences disease severity.

    METHODS: KP metabolites and cytokines in plasma samples of patients with dengue infection (dengue without warning signs [DWS-], dengue with warning signs [DWS+], or severe dengue) were analyzed. Cytokines (interferon gamma [IFN-ɣ], tumor necrosis factor, interleukin 6, CXCL10/interferon-inducile protein 10 [IP-10], interleukin 18 [IL-18], CCL2/monocyte chemoattractant protein-1 [MCP-1], and CCL4/macrophage inflammatory protein-1beta [MIP-1β] were assessed by a Human Luminex Screening Assay, while KP metabolites (tryptophan, kynurenine, anthranilic acid [AA], picolinic acid, and quinolinic acid) were assessed by ultra-high-performance liquid chromatography and Gas Chromatography Mass Spectrophotometry [GCMS] assays.

    RESULTS: Patients with DWS+ had increased activation of the KP where kynurenine-tryptophan ratio, anthranilic acid, and picolinic acid were elevated. These patients also had higher levels of the cytokines IFN-ɣ, CXCL10, CCL4, and IL-18 than those with DWS-. Further receiver operating characteristic analysis identified 3 prognostic biomarker candidates, CXCL10, CCL2, and AA, which predicted patients with higher risks of developing DWS+ with an accuracy of 97%.

    CONCLUSIONS: The data suggest a unique biochemical signature in patients with DWS+. CXCL10 and CCL2 together with AA are potential prognostic biomarkers that discern patients with higher risk of developing DWS+ at earlier stages of infection.

  8. Genetic characterization of dengue virus type 1 isolated in Brunei in 2005-2006
    Osman O, Fong MY, Sekaran SD
    J Gen Virol, 2009 Mar;90(Pt 3):678-686.
    PMID: 19218214 DOI: 10.1099/vir.0.005306-0
    The full-length genomes of two DENV-1 viruses isolated during the 2005-2006 dengue incidents in Brunei were sequenced. Twenty five primer sets were designed to amplify contiguous overlapping fragments of approximately 500-600 base pairs spanning the entire sequence of the genome. The amplified PCR products were sent to a commercial laboratory for sequencing and the nucleotides and the deduced amino acids were determined. Sequence analysis of the envelope gene at the nucleotide and amino acid levels between the two isolates showed 92 and 96 % identity, respectively. Comparison of the envelope gene sequences with 68 other DENV-1 viruses of known genotypes placed the two isolates into two different genotypic groups. Isolate DS06/210505 belongs to genotype V together with some of the recent isolates from India (2003) and older isolates from Singapore (1990) and Burma (1976), while isolate DS212/110306 was clustered in genotype IV with the prototype Nauru strain (1974) and with some of the recent isolates from Indonesia (2004) and the Philippines (2002, 2001). In the full-length genome analysis at the nucleotide level, isolate DS06/210505 showed 94 % identity to the French Guyana strain (1989) in genotype V while isolate DS212/110306 had 96 % identity to the Nauru Island strain (1974) in genotype IV. This work constitutes the first complete genetic characterization of not only Brunei DENV-1 virus isolates, but also the first strain from Borneo Island. This study was the first to report the isolation of dengue virus in the country.
  9. High dengue virus load differentially modulates human microvascular endothelial barrier function during early infection
    Soe HJ, Khan AM, Manikam R, Samudi Raju C, Vanhoutte P, Sekaran SD
    J Gen Virol, 2017 Dec;98(12):2993-3007.
    PMID: 29182510 DOI: 10.1099/jgv.0.000981
    Plasma leakage is the main pathophysiological feature in severe dengue, resulting from altered vascular barrier function associated with an inappropriate immune response triggered upon infection. The present study investigated functional changes using an electric cell-substrate impedance sensing system in four (brain, dermal, pulmonary and retinal) human microvascular endothelial cell (MEC) lines infected with purified dengue virus, followed by assessment of cytokine profiles and the expression of inter-endothelial junctional proteins. Modelling of changes in electrical impedance suggests that vascular leakage in dengue-infected MECs is mostly due to the modulation of cell-to-cell interactions, while this loss of vascular barrier function observed in the infected MECs varied between cell lines and DENV serotypes. High levels of inflammatory cytokines (IL-6 and TNF-α), chemokines (CXCL1, CXCL5, CXCL11, CX3CL1, CCL2 and CCL20) and adhesion molecules (VCAM-1) were differentially produced in the four infected MECs. Further, the tight junctional protein, ZO-1, was down-regulated in both the DENV-1-infected brain and pulmonary MECs, while claudin-1, PECAM-1 and VE-cadherin were differentially expressed in these two MECs after infection. Non-purified virus stock was also studied to investigate the impact of virus stock purity on dengue-specific immune responses, and the results suggest that virus stock propagated through cell culture may include factors that mask or alter the DENV-specific immune responses of the MECs. The findings of the present study show that high DENV load differentially modulates human microvascular endothelial barrier function and disrupts the function of inter-endothelial junctional proteins during early infection with organ-specific cytokine production.
  10. Fulltext African Trypanosome-Induced Blood-Brain Barrier Dysfunction under Shear Stress May Not Require ERK Activation
    Sumpio BJ, Chitragari G, Moriguchi T, Shalaby S, Pappas-Brown V, Khan AM, et al.
    Int. J. Angiol., 2015 Mar;24(1):41-6.
    PMID: 27053915 DOI: 10.1055/s-0034-1370890
    African trypanosomes are tsetse fly transmitted protozoan parasites responsible for human African trypanosomiasis, a disease characterized by a plethora of neurological symptoms and death. How the parasites under microvascular shear stress (SS) flow conditions in the brain cross the blood-brain barrier (BBB) is not known. In vitro studies using static models comprised of human brain microvascular endothelial cells (BMEC) show that BBB activation and crossing by trypanosomes requires the orchestration of parasite cysteine proteases and host calcium-mediated cell signaling. Here, we examine BMEC barrier function and the activation of extracellular signal-regulated kinase (ERK)1/2 and ERK5, mitogen-activated protein kinase family regulators of microvascular permeability, under static and laminar SS flow and in the context of trypanosome infection. Confluent human BMEC were cultured in electric cell-substrate impedance sensing (ECIS) and parallel-plate glass slide chambers. The human BMEC were exposed to 2 or 14 dyn/cm(2) SS in the presence or absence of trypanosomes. Real-time changes in transendothelial electrical resistance (TEER) were monitored and phosphorylation of ERK1/2 and ERK5 analyzed by immunoblot assay. After reaching confluence under static conditions human BMEC TEER was found to rapidly increase when exposed to 2 dyn/cm(2) SS, a condition that mimics SS in brain postcapillary venules. Addition of African trypanosomes caused a rapid drop in human BMEC TEER. Increasing SS to 14 dyn/cm(2), a condition mimicking SS in brain capillaries, led to a transient increase in TEER in both control and infected human BMEC. However, no differences in ERK1/2 and ERK5 activation were found under any condition tested. African trypanosomiasis alters BBB permeability under low shear conditions through an ERK1/2 and ERK5 independent pathway.
  11. Fulltext Positive outcomes of oil palm phenolics on degenerative diseases in animal models
    Sambanthamurthi R, Tan Y, Sundram K, Hayes KC, Abeywardena M, Leow SS, et al.
    Br J Nutr, 2011 Dec;106(11):1664-75.
    PMID: 21736778 DOI: 10.1017/S0007114511002133
    It is well established that plant phenolics elicit various biological activities, with positive effects on health. Palm oil production results in large volumes of aqueous by-products containing phenolics. In the present study, we describe the effects of oil palm phenolics (OPP) on several degenerative conditions using various animal models. OPP reduced blood pressure in a NO-deficient rat model, protected against ischaemia-induced cardiac arrhythmia in rats and reduced plaque formation in rabbits fed an atherogenic diet. In Nile rats, a spontaneous model of the metabolic syndrome and type 2 diabetes, OPP protected against multiple aspects of the syndrome and diabetes progression. In tumour-inoculated mice, OPP protected against cancer progression. Microarray studies on the tumours showed differential transcriptome profiles that suggest anti-tumour molecular mechanisms involved in OPP action. Thus, initial studies suggest that OPP may have potential against several chronic disease outcomes in mammals.
  12. Fulltext Cytokine factors present in dengue patient sera induces alterations of junctional proteins in human endothelial cells
    Appanna R, Wang SM, Ponnampalavanar SA, Lum LC, Sekaran SD
    Am J Trop Med Hyg, 2012 Nov;87(5):936-42.
    PMID: 22987650 DOI: 10.4269/ajtmh.2012.11-0606
    Plasma leakage in severe dengue has been postulated to be associated with skewed cytokine immune responses. In this study, the association of cytokines with vascular permeability in dengue patients was investigated. Human serum samples collected from 48 persons (13 with dengue fever, 29 with dengue hemorrhagic fever, and 6 healthy) were subjected to cytokines analysis by using Luminex Multiplex Technology. Selected serum samples from patients with dengue hemorrhagic fever sera and recombinant human cytokines were then tested for roles on inducing vascular permeability by treatment of human umbilical vein endothelial cells. Confocal immunofluorescence staining indicated morphologic alteration of human umbilical vein endothelial cells treated with serum samples from patients with dengue hemorrhagic fever compared with serum samples from healthy persons. The findings suggest that cytokines produced during dengue hemorrhagic infections could induce alterations in the vascular endothelium, which may play a fundamental role in the pathophysiology of dengue.
  13. Fulltext Early diagnosis of Dengue infection using a commercial Dengue Duo rapid test kit for the detection of NS1, IGM, and IGG
    Wang SM, Sekaran SD
    Am J Trop Med Hyg, 2010 Sep;83(3):690-5.
    PMID: 20810840 DOI: 10.4269/ajtmh.2010.10-0117
    A commercial Dengue Duo rapid test kit was evaluated for early dengue diagnosis by detection of dengue virus NS1 antigen and immunoglobulin M (IgM)/IgG antibodies. A total of 420 patient serum samples were subjected to real-time reverse transcription-polymerase chain reaction (RT-PCR), in-house IgM capture enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition assay, and the SD Dengue Duo rapid test. Of the 320 dengue acute and convalescent sera, dengue infection was detected by either serology or RT-PCR in 300 samples (93.75%), as compared with 289 samples (90.31%) in the combined SD Duo NS1/IgM. The NS1 detection rate is inversely proportional, whereas the IgM detection rate is directly proportional to the presence of IgG antibodies. The sensitivity and specificity in diagnosing acute dengue infection in the SD Duo NS1/IgM were 88.65% and 98.75%, respectively. The assay is sensitive and highly specific. Detection of both NS1 and IgM by SD Duo gave comparable detection rate by either serology or RT-PCR.
  14. Fulltext Disruption of adeB gene has a greater effect on resistance to meropenems than adeA gene in Acinetobacter spp. isolated from University Malaya Medical Centre
    Wong EW, Yusof MY, Mansor MB, Anbazhagan D, Ong SY, Sekaran SD
    Singapore Med J, 2009 Aug;50(8):822-6.
    PMID: 19710984
    The AdeABC pump of Acinetobacter spp. confers resistance to various antibiotic classes. This pump is composed of the AdeA, AdeB, and AdeC proteins where AdeB is a member of the resistance-nodulation-division efflux pump superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively. In this study, an attempt is made to elucidate the role of the AdeABC efflux pump in carbapenem resistance in Acinetobacter spp.
  15. Fulltext Rapid detection and serotyping of dengue virus by multiplex RT-PCR and real-time SYBR green RT-PCR
    Yong YK, Thayan R, Chong HT, Tan CT, Sekaran SD
    Singapore Med J, 2007 Jul;48(7):662-8.
    PMID: 17609830
    Dengue fever and dengue haemorrhagic fever currently rank highly among the newly-emerging infectious diseases, and are considered to be the most important arboviral disease worldwide. The definitive diagnosis is culture analysis, but practical considerations limit its use. Also, the period for viral detection is limited. Within a day or two after fever subsides, rising levels of antibodies interfere with viral cultures. An alternative to this quandary is the use of viral RNA detection assays. In our laboratory, a reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed using a set of degenerate primers.
  16. Caffeic acid phenethyl ester (CAPE): scavenger of peroxynitrite in vitro and in sepsis models
    Kassim M, Mansor M, Kamalden TA, Shariffuddin II, Hasan MS, Ong G, et al.
    Shock, 2014 Aug;42(2):154-60.
    PMID: 24667629 DOI: 10.1097/SHK.0000000000000179
    Excessive free radical production by immune cells has been linked to cell death and tissue injury during sepsis. Peroxynitrite is a short-lived oxidant and a potent inducer of cell death that has been identified in several pathological conditions. Caffeic acid phenethyl ester (CAPE) is an active component of honeybee products and exhibits antioxidant, anti-inflammatory, and immunomodulatory activities. The present study examined the ability of CAPE to scavenge peroxynitrite in RAW 264.7 murine macrophages stimulated with lipopolysaccharide/interferon-γ that was used as an in vitro model. Conversion of 123-dihydrorhodamine to its oxidation product 123-rhodamine was used to measure peroxynitrite production. Two mouse models of sepsis (endotoxemia and cecal ligation and puncture) were used as in vivo models. The level of serum 3-nitrotyrosine was used as an in vivo marker of peroxynitrite. The results demonstrated that CAPE significantly improved the viability of lipopolysaccharide/interferon-γ-treated RAW 264.7 cells and significantly inhibited nitric oxide production, with effects similar to those observed with an inhibitor of inducible nitric oxide synthase (1400W). In addition, CAPE exclusively inhibited the synthesis of peroxynitrite from the artificial substrate SIN-1 and directly prevented the peroxynitrite-mediated conversion of dihydrorhodamine-123 to its fluorescent oxidation product rhodamine-123. In both sepsis models, CAPE inhibited cellular peroxynitrite synthesis, as evidenced by the absence of serum 3-nitrotyrosine, an in vivo marker of peroxynitrite. Thus, CAPE attenuates the inflammatory responses that lead to cell damage and, potentially, cell death through suppression of the production of cytotoxic molecules such as nitric oxide and peroxynitrite. These observations provide evidence of the therapeutic potential of CAPE treatment for a wide range of inflammatory disorders.
  17. Fulltext Rapid immunoglobulin M-based dengue diagnostic test using surface plasmon resonance biosensor
    Jahanshahi P, Zalnezhad E, Sekaran SD, Adikan FR
    Sci Rep, 2014 Jan 24;4:3851.
    PMID: 24458089 DOI: 10.1038/srep03851
    Surface plasmon resonance (SPR) is a medical diagnosis technique with high sensitivity and specificity. In this research, a new method based on SPR is proposed for rapid, 10-minute detection of the anti-dengue virus in human serum samples. This novel technique, known as rapid immunoglobulin M (IgM)-based dengue diagnostic test, can be utilized quickly and easily at the point of care. Four dengue virus serotypes were used as ligands on a biochip. According to the results, a serum volume of only 1 μl from a dengue patient (as a minimized volume) is required to indicate SPR angle variation to determine the ratio of each dengue serotype in samples with 83-93% sensitivity and 100% specificity.
  18. Fulltext Transcriptome analysis of Streptococcus pneumoniae treated with the designed antimicrobial peptides, DM3
    Le CF, Gudimella R, Razali R, Manikam R, Sekaran SD
    Sci Rep, 2016 05 26;6:26828.
    PMID: 27225022 DOI: 10.1038/srep26828
    In our previous studies, we generated a short 13 amino acid antimicrobial peptide (AMP), DM3, showing potent antipneumococcal activity in vitro and in vivo. Here we analyse the underlying mechanisms of action using Next-Generation transcriptome sequencing of penicillin (PEN)-resistant and PEN-susceptible pneumococci treated with DM3, PEN, and combination of DM3 and PEN (DM3PEN). DM3 induced differential expression in cell wall and cell membrane structural and transmembrane processes. Notably, DM3 altered the expression of competence-induction pathways by upregulating CelA, CelB, and CglA while downregulating Ccs16, ComF, and Ccs4 proteins. Capsular polysaccharide subunits were downregulated in DM3-treated cells, however, it was upregulated in PEN- and DM3PEN-treated groups. Additionally, DM3 altered the amino acids biosynthesis pathways, particularly targeting ribosomal rRNA subunits. Downregulation of cationic AMPs resistance pathway suggests that DM3 treatment could autoenhance pneumococci susceptibility to DM3. Gene enrichment analysis showed that unlike PEN and DM3PEN, DM3 treatment exerted no effect on DNA-binding RNA polymerase activity but observed downregulation of RpoD and RNA polymerase sigma factor. In contrast to DM3, DM3PEN altered the regulation of multiple purine/pyrimidine biosynthesis and metabolic pathways. Future studies based on in vitro experiments are proposed to investigate the key pathways leading to pneumococcal cell death caused by DM3.
  19. Fulltext In vitro properties of designed antimicrobial peptides that exhibit potent antipneumococcal activity and produces synergism in combination with penicillin
    Le CF, Yusof MY, Hassan H, Sekaran SD
    Sci Rep, 2015;5:9761.
    PMID: 25985150 DOI: 10.1038/srep09761
    Antimicrobial peptides (AMPs) represent a promising class of novel antimicrobial agents owing to their potent antimicrobial activity. In this study, two lead peptides from unrelated classes of AMPs were systematically hybridized into a series of five hybrid peptides (DM1-DM5) with conserved N- and C-termini. This approach allows sequence bridging of two highly dissimilar AMPs and enables sequence-activity relationship be detailed down to single amino acid level. Presence of specific amino acids and physicochemical properties were used to describe the antipneumococcal activity of these hybrids. Results obtained suggested that cell wall and/or membrane targeting could be the principal mechanism exerted by the hybrids leading to microbial cell killing. Moreover, the pneumocidal rate was greater than penicillin (PEN). Combination treatment with both DMs and PEN produced synergism. The hybrids were also broad spectrum against multiple common clinical bacteria. Sequence analysis showed that presence of specific residues has a major role in affecting the antimicrobial and cell toxicity of the hybrids than physicochemical properties. Future studies should continue to investigate the mechanisms of actions, in vivo therapeutic potential, and improve rational peptide design based on the current strategy.
  20. Fulltext In vivo efficacy and molecular docking of designed peptide that exhibits potent antipneumococcal activity and synergises in combination with penicillin
    Le CF, Yusof MY, Hassan MA, Lee VS, Isa DM, Sekaran SD
    Sci Rep, 2015;5:11886.
    PMID: 26156658 DOI: 10.1038/srep11886
    We have previously designed a series of antimicrobial peptides (AMPs) and in the current study, the in vivo therapeutic efficacy and toxicity were investigated. Among all the peptides, DM3 conferred protection to a substantial proportion of the lethally infected mice caused by a strain of penicillin-resistant Streptococcus pneumoniae. Synergism was reported and therapeutic efficacy was significantly enhanced when DM3 was formulated in combination with penicillin (PEN). No toxicity was observed in mice receiving these treatments. The in silico molecular docking study results showed that, DM3 has a strong affinity towards three protein targets; autolysin and pneumococcal surface protein A (pspA). Thus AMPs could serve as supporting therapeutics in combination with conventional antibiotics to enhance treatment outcome.
Related Terms
Filters
Contact Us

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

External Links