Displaying publications 1 - 20 of 263 in total

  1. Okubo Y
    Malays J Pathol, 2017 08;39(2):207-208.
    PMID: 28866707
    No abstract available.
    Matched MeSH terms: Virulence/genetics*; Virulence Factors/genetics*; Virulence Factors/metabolism
  2. Pang T
    Trends Microbiol., 1998 Sep;6(9):339-42.
    PMID: 9778724
    Matched MeSH terms: Virulence/genetics; Virulence/immunology
  3. Aisyah Mohamed Rehan, Mohammad Izwan Enche Othman, Nor Munirah Mohd Amin, Intan Azura Shahdan, Hanani Ahmad Yusof@Hanafi
    Streptococcus pneumoniae (S. pneumoniae) is a gram-positive diplococci belonging to the genus Streptococcus and it is a well-studied pathogenic bacterium. Pneumococcal diseases such as otitis media, pneumonia, sepsis and meningitis caused by pathogenic strains of S. pneumoniae still brought significant mortality and morbidity worldwide. The pathogenicity of S. pneumoniae is exerted by various virulence factors and one of it is the enzyme hyaluronate lyase. Hyaluronate lyase plays a major role in
    the invasive capability of S. pneumoniae. Its mechanism of action and crystallographic
    structure have been determinedbut its regulatory mechanism is still poorly understood.
    Drawing connections between the nutritional behaviour and invasive property of S.
    pneumoniae, CodY regulator is hypothesized as a potential hyaluronate lyase regulator.
    This work was aimed to construct CodY deficient mutant of S. pneumoniae to form
    foundational work for the study of CodY regulatory effect on hyaluronate lyase.
    Matched MeSH terms: Virulence; Virulence Factors
  4. Harun A
    Malays J Med Sci, 2014 Nov-Dec;21(6):1-2.
    PMID: 25897275
    The emergence of fungal species as opportunistic pathogens has warranted further studies on their pathogenicity, epidemiology, and transmissibility. Fungal genotyping has been employed to study the genetic relatedness within the organism, in order to obtain answers to epidemiological questions (such as in outbreak confirmation) as well as to provide basis for the improvement for patients care. Various fungal genotyping methods have been previously published, which can be chosen depending on the intended use and the capability of individual laboratory.
    Matched MeSH terms: Virulence
  5. Osman HA, Hasan H, Suppian R, Hassan S, Andee DZ, Abdul Majid N, et al.
    Turk J Med Sci, 2015;45(4):940-6.
    PMID: 26422871
    BACKGROUND/AIM: The severity of disease outcome in dyspepsia has been attributed to Helicobacter pylori virulence genes. The aim of this study was to determine the distribution of H. pylori virulence genes (cagA, babA2, and dupA) and to determine whether or not there arises a significant correlation with clinical dyspepsia outcomes.

    MATERIALS AND METHODS: H. pylori genotypes cagA, babA2, and dupA were identified by polymerase chain reactions from gastric biopsy samples in 105 H. pylori-positive patients.

    RESULTS: The positive rates for cagA, babA2, and dupA genes in H. pylori dyspeptic patients were 69.5%, 41.0%, and 22.9%, respectivel cagA was more prevalent in Indians (39.7%), babA2 was more prevalent in Malays (39.5%), and dupA detection occurred more frequently in both Indians and Malays and at the same rate (37.5%). The Chinese inhabitants had the lowest prevalence of the three genes. Nonulcer disease patients had a significantly higher distribution of cagA (76.7%), babA2 (74.4%), and dupA (75.0%). There was no apparent association between these virulence genes and the clinical outcomes.

    CONCLUSION: The lower prevalence of these genes and variations among different ethnicities implies that the strains are geographically and ethnically dependent. None of the virulence genes were knowingly beneficial in predicting the clinical outcome of H. pylori infection in our subjects.

    Matched MeSH terms: Virulence/genetics; Virulence Factors/genetics*
  6. Reeki Emrizal, Nor Azlan Nor Muhammad
    Sains Malaysiana, 2018;47:2941-2950.
    Porphyromonas gingivalis is the bacterium responsible for chronic periodontitis, a severe periodontal disease. Virulence
    factors produced by this bacterium are secreted by the Type IX Secretion System (T9SS). The specific functions for
    each protein component of the T9SS have yet to be characterized thus limiting our understanding of the mechanisms
    associated with the translocation and modification processes of the T9SS. This study aims to identify the sequence motifs
    for each T9SS component and predict the functions associated with each discovered motif using motif comparisons. We
    extracted the sequences of 20 T9SS components from the P. gingivalis proteome that were experimentally identified to
    be important for T9SS function and used them for homology searching against fully sequenced bacterial proteomes.
    We developed a rigorous pipeline for the identification of seed sequences for each protein family of T9SS components.
    We verified that each selected seed sequence are true members of the protein family hence sharing conserved sequence
    motifs using profile Hidden Markov Models. The motifs for each T9SS component are identified and compared to motifs
    in the Pfam database. The discovered motifs for 11 components with known functions matched the motifs associated
    with the reported functions. We also suggested the putative functions for four components. PorM and PorW might form
    the putative energy transduction complex. PorP and PorT might be the putative O-deacylases. The identified motifs for
    five components matched the motifs associated with functions that related/unrelated to the T9SS.
    Matched MeSH terms: Virulence
  7. McMinn PC
    FEMS Microbiol. Rev., 2002 Mar;26(1):91-107.
    PMID: 12007645
    Since its discovery in 1969, enterovirus 71 (EV71) has been recognised as a frequent cause of epidemics of hand-foot-and-mouth disease (HFMD) associated with severe neurological sequelae in a small proportion of cases. There has been a significant increase in EV71 epidemic activity throughout the Asia-Pacific region since 1997. Recent HFMD epidemics in this region have been associated with a severe form of brainstem encephalitis associated with pulmonary oedema and high case-fatality rates. The emergence of large-scale epidemic activity in the Asia-Pacific region has been associated with the circulation of three genetic lineages that appear to be undergoing rapid evolutionary change. Two of these lineages (B3 and B4) have not been described previously and appear to have arisen from an endemic focus in equatorial Asia, which has served as a source of virus for HFMD epidemics in Malaysia, Singapore and Australia. The third lineage (C2) has previously been identified [Brown, B.A. et al. (1999) J. Virol. 73, 9969-9975] and was primarily responsible for the large HFMD epidemic in Taiwan during 1998. As EV71 appears not to be susceptible to newly developed antiviral agents and a vaccine is not currently available, control of EV71 epidemics through high-level surveillance and public health intervention needs to be maintained and extended throughout the Asia-Pacific region. Future research should focus on (1) understanding the molecular genetics of EV71 virulence, (2) identification of the receptor(s) for EV71, (3) development of antiviral agents to ameliorate the severity of neurological disease and (4) vaccine development to control epidemics. Following the successful experience of the poliomyelitis control programme, it may be possible to control EV71 epidemics if an effective live-attenuated vaccine is developed.
    Matched MeSH terms: Virulence/genetics
  8. Low CF, Shamsir MS, Mohamed-Hussein ZA, Baharum SN
    PeerJ, 2019;7:e6568.
    PMID: 30984478 DOI: 10.7717/peerj.6568
    Pathologically relevant behaviors of Vibrio, such as the expression of virulence factors, biofilm production, and swarming motility, have been shown to be controlled by quorum sensing. The autoinducer-2 quorum sensing receptor protein LuxP is one of the target proteins for drug development to suppress the virulence of Vibrio. Here, we reported the potential molecular interaction of fatty acids identified in vibriosis-resistant grouper with LuxP. Fatty acid, 4-oxodocosahexaenoic acid (4R8) showed significant binding affinity toward LuxP (-6.0 kcal/mol) based on molecular docking analysis. The dynamic behavior of the protein-ligand complex was illustrated by molecular dynamic simulations. The fluctuation of the protein backbone, the stability of ligand binding, and hydrogen bond interactions were assessed, suggesting 4R8 possesses potential interaction with LuxP, which was supported by the low binding free energy (-29.144 kJ/mol) calculated using the molecular mechanics Poisson-Boltzmann surface area.
    Matched MeSH terms: Virulence; Virulence Factors
  9. Al-Maleki AR, Mariappan V, Vellasamy KM, Shankar EM, Tay ST, Vadivelu J
    J Proteomics, 2014 Jun 25;106:205-20.
    PMID: 24742602 DOI: 10.1016/j.jprot.2014.04.005
    Colony morphology variation is a characteristic of Burkholderia pseudomallei primary clinical isolates, associated with variations in expression of virulence factors. Here, we performed comparative investigations on adhesion, invasion, plaque-forming abilities and protein profiles of B. pseudomallei wild-type (WT) and a small colony variant (SCV). The percentage of SCV adherence to A549 cells was significantly higher (2.73%) than WT (1.91%). In contrast, WT was significantly more efficient (0.63%) than SCV (0.31%) in invasiveness and in inducing cellular damage. Using 2-DE and MALDI TOF/TOF, 263 and 258 protein spots were detected in WT and SCV, respectively. Comparatively, 49 proteins were differentially expressed in SCV when compared with WT. Of these, 31 proteins were up-regulated, namely, nucleoside diphosphate kinase (Ndk), phosphoglycerate kinase (Pgk), thioredoxin (TrxA), putative ferritin DPS-family DNA-binding protein (DPS) and oxidoreductase (AhpC) that are known to be involved in adhesion, intracellular survival and persistence. However, among the 18 down-regulated proteins, enolase (Eno), elongation factor (EF-Tu) and universal stress-related proteins were associated with invasion and virulence. Differences observed in these protein profiles provide ample clues to their association with the morphotypic and phenotypic characteristics of colony variants, providing additional insights into the potential association of B. pseudomallei colony morphotypes with disease pathogenesis.
    Matched MeSH terms: Virulence/genetics; Virulence Factors/metabolism*
  10. Loo D
    Med J Malaya, 1965 Jun;19(4):259-62.
    PMID: 4220849
    Matched MeSH terms: Virulence
  11. Lim SY, Teh CSJ, Thong KL
    OMICS, 2017 10;21(10):592-602.
    PMID: 29049010 DOI: 10.1089/omi.2017.0119
    Enterococcus faecium is an opportunistic pathogen with a remarkable ability to acquire resistance toward multiple antibiotics, including those of last-resort drugs such as vancomycin and daptomycin. The occurrence of vancomycin-resistant E. faecium is on the rise and there is a need to understand the virulence of this organism. One of the factors that contributes to the virulence is the ability to form biofilms. Since bacteria in biofilm state are more resistant to antibiotics and host immune response, understanding the molecular mechanism of biofilm development is important to control biofilm-related diseases. The aim of this study was to determine the global gene expression profiles of an E. faecium strain, VREr5, during the early event of sessile growth compared with its planktonic phase through RNA-sequencing approach. The results clearly illustrated distinct expression profiles of the planktonic and biofilm cells. A total of 177 genes were overexpressed in the biofilm cells. Most of them encode for proteins involved in adherence, such as the ebpABCfm locus. Genes associated with plasmid replication, gene exchange, and protein synthesis were also upregulated during the early event of biofilm development. Furthermore, the transcriptome analysis also identified genes such as fsrB, luxS, and spx that might suppress biofilm formation in VREr5. The putative biofilm-related bee locus was found to be downregulated. These new findings could provide caveats for future studies on the regulation and maintenance of biofilm and development of biomarkers for biofilm-related diseases.
    Matched MeSH terms: Virulence/genetics; Virulence Factors/genetics
  12. Yun, Mei Lai, Myo, Thura Zaw, Nor Amalina Emran, Lin, Zaw
    Escherichia coli sequence type 131 (ST131) carries multiple drug resistance (MDR) genes as well as virulence genes. Drug resistant characteristics give a management problem to health care personnel. Four MDR Escherichia coli ST131 H30-Rx subclones were identified among 80 Uropathogenic E. coli (UPEC) isolates by using 4 allelic-specific Polymerase Chain Reactions (PCR) in two hospitals of Kota Kinabalu, Sabah, Malaysia. There is emergence of multidrug resistant E. coli in Kota Kinabalu.
    Matched MeSH terms: Virulence
  13. Mandary MB, Masomian M, Poh CL
    Int J Mol Sci, 2019 Sep 19;20(18).
    PMID: 31546962 DOI: 10.3390/ijms20184657
    RNA viruses are known to replicate by low fidelity polymerases and have high mutation rates whereby the resulting virus population tends to exist as a distribution of mutants. In this review, we aim to explore how genetic events such as spontaneous mutations could alter the genomic organization of RNA viruses in such a way that they impact virus replications and plaque morphology. The phenomenon of quasispecies within a viral population is also discussed to reflect virulence and its implications for RNA viruses. An understanding of how such events occur will provide further evidence about whether there are molecular determinants for plaque morphology of RNA viruses or whether different plaque phenotypes arise due to the presence of quasispecies within a population. Ultimately this review gives an insight into whether the intrinsically high error rates due to the low fidelity of RNA polymerases is responsible for the variation in plaque morphology and diversity in virulence. This can be a useful tool in characterizing mechanisms that facilitate virus adaptation and evolution.
    Matched MeSH terms: Virulence
  14. Soheili S, Ghafourian S, Sekawi Z, Neela V, Sadeghifard N, Ramli R, et al.
    ScientificWorldJournal, 2014;2014:623174.
    PMID: 25147855 DOI: 10.1155/2014/623174
    Enterococcus, a Gram-positive facultative anaerobic cocci belonging to the lactic acid bacteria of the phylum Firmicutes, is known to be able to resist a wide range of hostile conditions such as different pH levels, high concentration of NaCl (6.5%), and the extended temperatures between 5(°)C and 65(°)C. Despite being the third most common nosocomial pathogen, our understanding on its virulence factors is still poorly understood. The current study was aimed to determine the prevalence of different virulence genes in Enterococcus faecalis and Enterococcus faecium. For this purpose, 79 clinical isolates of Malaysian enterococci were evaluated for the presence of virulence genes. pilB, fms8, efaAfm, and sgrA genes are prevalent in all clinical isolates. In conclusion, the pathogenicity of E. faecalis and E. faecium could be associated with different virulence factors and these genes are widely distributed among the enterococcal species.
    Matched MeSH terms: Virulence; Virulence Factors/genetics*
  15. Puah SM, Puthucheary SD, Wang JT, Pan YJ, Chua KH
    ScientificWorldJournal, 2014;2014:590803.
    PMID: 25215325 DOI: 10.1155/2014/590803
    The Gram-negative saprophyte Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease which is endemic in Southeast Asia and northern Australia. This bacterium possesses many virulence factors which are thought to contribute to its survival and pathogenicity. Using a virulent clinical isolate of B. pseudomallei and an attenuated strain of the same B. pseudomallei isolate, 6 genes BPSL2033, BP1026B_I2784, BP1026B_I2780, BURPS1106A_A0094, BURPS1106A_1131, and BURPS1710A_1419 were identified earlier by PCR-based subtractive hybridization. These genes were extensively characterized at the molecular level, together with an additional gene BPSL3147 that had been identified by other investigators. Through a reverse genetic approach, single-gene knockout mutants were successfully constructed by using site-specific insertion mutagenesis and were confirmed by PCR. BPSL2033::Km and BURPS1710A_1419::Km mutants showed reduced rates of survival inside macrophage RAW 264.7 cells and also low levels of virulence in the nematode infection model. BPSL2033::Km demonstrated weak statistical significance (P = 0.049) at 8 hours after infection in macrophage infection study but this was not seen in BURPS1710A_1419::Km. Nevertheless, complemented strains of both genes were able to partially restore the gene defects in both in vitro and in vivo studies, thus suggesting that they individually play a minor role in the virulence of B. pseudomallei.
    Matched MeSH terms: Virulence/genetics*; Virulence Factors
  16. Rajamanikam A, Govind SK
    Parasit Vectors, 2013;6(1):295.
    PMID: 24499467 DOI: 10.1186/1756-3305-6-295
    Blastocystis spp. are one of the most prevalent parasites isolated from patients suffering from diarrhea, flatulence, constipation and vomiting. It's pathogenicity and pathophysiology remains controversial to date. Protease activity and amoebic forms have been reported previously in symptomatic isolates but there has been no conclusive evidence provided to correlate the protease activity and any specific life cycle stage of the parasite thus far.
    Matched MeSH terms: Virulence Factors/metabolism*; Virulence Factors/chemistry
  17. Tay ST, Kho KL, Lye SF, Ngeow YF
    J. Vet. Med. Sci., 2018 Apr 18;80(4):653-661.
    PMID: 29311425 DOI: 10.1292/jvms.17-0448
    Bartonella bovis is a small Gram-negative bacterium recognized as an etiological agent for bacteremia and endocarditis in cattle. As few reports are available on the taxonomic position of B. bovis and its mechanism of virulence, this study aims to resolve the phylogeny of B. bovis and investigate putative virulence genes based on whole genome sequence analysis. Genome-wide comparisons based on single nucleotide polymorphisms (SNP) and orthologous genes were performed in this study for phylogenetic inference of 27 Bartonella species. Rapid Annotation using Subsystem Technology (RAST) analysis was used for annotation of putative virulence genes. The phylogenetic tree generated from the genome-wide comparison of orthologous genes exhibited a topology almost similar to that of the tree generated from SNP-based comparison, indicating a high concordance in the nucleotide and amino acid sequences of Bartonella spp. The analyses show consistent grouping of B. bovis in a cluster related to ruminant-associated species, including Bartonella australis, Bartonella melophagi and Bartonella schoenbuchensis. RAST analysis revealed genes encoding flagellar components, in corroboration with the observation of flagella-like structure of BbUM strain under negative straining. Genes associated with virulence, disease and defence, prophages, membrane transport, iron acquisition, motility and chemotaxis are annotated in B. bovis genome. The flagellin (flaA) gene of B. bovis is closely related to Bartonella bacilliformis and Bartonella clarridgeiae but distinct from other Gram-negative bacteria. The absence of type IV secretion systems, the bona fide pathogenicity factors of bartonellae, in B. bovis suggests that it may have a different mechanism of pathogenicity.
    Matched MeSH terms: Virulence; Virulence Factors/genetics*
  18. Chong YM, How KY, Yin WF, Chan KG
    Molecules, 2018 04 21;23(4).
    PMID: 29690523 DOI: 10.3390/molecules23040972
    The quorum sensing (QS) system has been used by many opportunistic pathogenic bacteria to coordinate their virulence determinants in relation to cell-population density. As antibiotic-resistant bacteria are on the rise, interference with QS has been regarded as a novel way to control bacterial infections. As such, many plant-based natural products have been widely explored for their therapeutic roles. These natural products may contain anti-QS compounds that could block QS signals generation or transmission to combat QS pathogens. In this study, we report the anti-QS activities of four different Chinese herbal plant extracts: Poria cum Radix pini, Angelica dahurica, Rhizoma cibotii and Schizonepeta tenuifolia, on Pseudomonas aeruginosa PAO1. All the plants extracted using hexane, chloroform and methanol were tested and found to impair swarming motility and pyocyanin production in P.aeruginosa PAO1, particularly by Poria cum Radix pini. In addition, all the plant extracts also inhibited violacein production in C.violaceum CV026 up to 50% while bioluminescence activities were reduced in lux-based E. coli biosensors, pSB401 and pSB1075, up to about 57%. These anti-QS properties of the four medicinal plants are the first documentation that demonstrates a potential approach to attenuate pathogens’ virulence determinants.
    Matched MeSH terms: Virulence/drug effects; Virulence/genetics
  19. Tee HK, Tan CW, Yogarajah T, Lee MHP, Chai HJ, Hanapi NA, et al.
    PLoS Pathog., 2019 11;15(11):e1007863.
    PMID: 31730673 DOI: 10.1371/journal.ppat.1007863
    Enterovirus A71 (EV-A71) causes hand, foot and mouth disease epidemics with neurological complications and fatalities. However, the neuropathogenesis of EV-A71 remains poorly understood. In mice, adaptation and virulence determinants have been mapped to mutations at VP2-149, VP1-145 and VP1-244. We investigate how these amino acids alter heparin-binding phenotype and shapes EV-A71 virulence in one-day old mice. We constructed six viruses with varying residues at VP1-98, VP1-145 (which are both heparin-binding determinants) and VP2-149 (based on the wild type 149K/98E/145Q, termed KEQ) to generate KKQ, KKE, KEE, IEE and IEQ variants. We demonstrated that the weak heparin-binder IEE was highly lethal in mice. The initially strong heparin-binding IEQ variant acquired an additional mutation VP1-K244E, which confers weak heparin-binding phenotype resulting in elevated viremia and increased virus antigens in mice brain, with subsequent high virulence. IEE and IEQ-244E variants inoculated into mice disseminated efficiently and displayed high viremia. Increasing polymerase fidelity and impairing recombination of IEQ attenuated the virulence, suggesting the importance of population diversity in EV-A71 pathogenesis in vivo. Combining in silico docking and deep sequencing approaches, we inferred that virus population diversity is shaped by electrostatic interactions at the five-fold axis of the virus surface. Electrostatic surface charges facilitate virus adaptation by generating poor heparin-binding variants for better in vivo dissemination in mice, likely due to reduced adsorption to heparin-rich peripheral tissues, which ultimately results in increased neurovirulence. The dynamic switching between heparin-binding and weak heparin-binding phenotype in vivo explained the neurovirulence of EV-A71.
    Matched MeSH terms: Virulence; Virulence Factors/genetics; Virulence Factors/metabolism*; Virulence Factors/chemistry
  20. Alexeev D, Kostrjukova E, Aliper A, Popenko A, Bazaleev N, Tyakht A, et al.
    J. Proteome Res., 2012 Jan 1;11(1):224-36.
    PMID: 22129229 DOI: 10.1021/pr2008626
    To date, no genome of any of the species from the genus Spiroplasma has been completely sequenced. Long repetitive sequences similar to mobile units present a major obstacle for current genome sequencing technologies. Here, we report the assembly of the Spiroplasma melliferum KC3 genome into 4 contigs, followed by proteogenomic annotation and metabolic reconstruction based on the discovery of 521 expressed proteins and comprehensive metabolomic profiling. A systems approach allowed us to elucidate putative pathogenicity mechanisms and to discover major virulence factors, such as Chitinase utilization enzymes and toxins never before reported for insect pathogenic spiroplasmas.
    Matched MeSH terms: Virulence Factors/genetics*; Virulence Factors/metabolism
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