Displaying publications 301 - 320 of 456 in total

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  1. Fulltext Characterisation of genotype VII Newcastle disease virus (NDV) isolated from NDV vaccinated chickens, and the efficacy of LaSota and recombinant genotype VII vaccines against challenge with velogenic NDV
    Roohani K, Tan SW, Yeap SK, Ideris A, Bejo MH, Omar AR
    J Vet Sci, 2015;16(4):447-57.
    PMID: 25643805 DOI: 10.4142/jvs.2015.16.4.447
    A Newcastle disease virus (NDV) isolate designated IBS002 was isolated from a commercial broiler farm in Malaysia. The virus was characterised as a virulent strain based on the multiple basic amino acid motif of the fusion (F) cleavage site (112)RRRKGF(117) and length of the C-terminus extension of the hemagglutinin-neuraminidase (HN) gene. Furthermore, IBS002 was classified as a velogenic NDV with mean death time (MDT) of 51.2 h and intracerebral pathogenicity index (ICPI) of 1.76. A genetic distance analysis based on the full-length F and HN genes showed that both velogenic viruses used in this study, genotype VII NDV isolate IBS002 and genotype VIII NDV isolate AF2240-I, had high genetic variations with genotype II LaSota vaccine. In this study, the protection efficacy of the recombinant genotype VII NDV inactivated vaccine was also evaluated when added to an existing commercial vaccination program against challenge with velogenic NDV IBS002 and NDV AF2240-I in commercial broilers. The results indicated that both LaSota and recombinant genotype VII vaccines offered full protection against challenge with AF2240-I. However, the LaSota vaccine only conferred partial protection against IBS002. In addition, significantly reduced viral shedding was observed in the recombinant genotype VII-vaccinated chickens compared to LaSota-vaccinated chickens.
    Matched MeSH terms: Virulence
  2. [Encephalomyelitis caused by enterovirus type 71 in children]
    Koroleva GA, Lukashev AN, Khudiakova LV, Mustafina AN, Lashkevich VA
    Vopr. Virusol., 2010 Nov-Dec;55(6):4-10.
    PMID: 21381332
    Enterovirus type 71 (EV71) is a causative agent of large outbreaks of hand, foot, and mouth disease (HFMD) in Europe (Bulgaria, 1975; Hungary, 1978) and South-East Asia (Malaysia, 1977; Taiwan, 1998; Singapore, 2000-2007; People's Republic of China, 2007-2009). HFMD afflicted children less than 10 years of age and resulted in recovery within 3-7 days. In a small percentage of infants (aged 6 months to 3 years), HFMD was accompanied by acute neurological complications, such as serous meningitis, poliomyelitis-like syndrome (extremity pareses and muscle paralyses); brain stem encephalitis (myoclonic jerks, tremor, lethargy, swallowing and speech disorders, cardiopulmonary failure, pulmonary edema, shock, coma, death). X-ray study revealed pulmonary hemorrhages and edema. Mortality rates were as high as 82-94% in severe cases. Incapacitating motor, respiratory, and psychoemotional disorders persisted in some surviving children. Pathomorphologically, patients with central nervous system disease and cardiopulmonary failure were found to have acute inflammation of the grey matter of the brain stem (medulla oblongata, pons) and spinal cord. Inflammatory changes in the lung and myocardial tissues were negligible or absent. Fatal pulmonary edema was neurogenic in origin and resulted from damage to the respiratory and vasomotor centers of the brain stem.
    Matched MeSH terms: Virulence
  3. Fulltext NeisseriaBase: a specialised Neisseria genomic resource and analysis platform
    Zheng W, Mutha NV, Heydari H, Dutta A, Siow CC, Jakubovics NS, et al.
    PeerJ, 2016;4:e1698.
    PMID: 27017950 DOI: 10.7717/peerj.1698
    Background. The gram-negative Neisseria is associated with two of the most potent human epidemic diseases: meningococcal meningitis and gonorrhoea. In both cases, disease is caused by bacteria colonizing human mucosal membrane surfaces. Overall, the genus shows great diversity and genetic variation mainly due to its ability to acquire and incorporate genetic material from a diverse range of sources through horizontal gene transfer. Although a number of databases exist for the Neisseria genomes, they are mostly focused on the pathogenic species. In this present study we present the freely available NeisseriaBase, a database dedicated to the genus Neisseria encompassing the complete and draft genomes of 15 pathogenic and commensal Neisseria species. Methods. The genomic data were retrieved from National Center for Biotechnology Information (NCBI) and annotated using the RAST server which were then stored into the MySQL database. The protein-coding genes were further analyzed to obtain information such as calculation of GC content (%), predicted hydrophobicity and molecular weight (Da) using in-house Perl scripts. The web application was developed following the secure four-tier web application architecture: (1) client workstation, (2) web server, (3) application server, and (4) database server. The web interface was constructed using PHP, JavaScript, jQuery, AJAX and CSS, utilizing the model-view-controller (MVC) framework. The in-house developed bioinformatics tools implemented in NeisseraBase were developed using Python, Perl, BioPerl and R languages. Results. Currently, NeisseriaBase houses 603,500 Coding Sequences (CDSs), 16,071 RNAs and 13,119 tRNA genes from 227 Neisseria genomes. The database is equipped with interactive web interfaces. Incorporation of the JBrowse genome browser in the database enables fast and smooth browsing of Neisseria genomes. NeisseriaBase includes the standard BLAST program to facilitate homology searching, and for Virulence Factor Database (VFDB) specific homology searches, the VFDB BLAST is also incorporated into the database. In addition, NeisseriaBase is equipped with in-house designed tools such as the Pairwise Genome Comparison tool (PGC) for comparative genomic analysis and the Pathogenomics Profiling Tool (PathoProT) for the comparative pathogenomics analysis of Neisseria strains. Discussion. This user-friendly database not only provides access to a host of genomic resources on Neisseria but also enables high-quality comparative genome analysis, which is crucial for the expanding scientific community interested in Neisseria research. This database is freely available at http://neisseria.um.edu.my.
    Matched MeSH terms: Virulence
  4. Fulltext Porphyromonas gingivalis: An Overview of Periodontopathic Pathogen below the Gum Line
    How KY, Song KP, Chan KG
    Front Microbiol, 2016;7:53.
    PMID: 26903954 DOI: 10.3389/fmicb.2016.00053
    Periodontal disease represents a group of oral inflammatory infections initiated by oral pathogens which exist as a complex biofilms on the tooth surface and cause destruction to tooth supporting tissues. The severity of this disease ranges from mild and reversible inflammation of the gingiva (gingivitis) to chronic destruction of connective tissues, the formation of periodontal pocket and ultimately result in loss of teeth. While human subgingival plaque harbors more than 500 bacterial species, considerable research has shown that Porphyromonas gingivalis, a Gram-negative anaerobic bacterium, is the major etiologic agent which contributes to chronic periodontitis. This black-pigmented bacterium produces a myriad of virulence factors that cause destruction to periodontal tissues either directly or indirectly by modulating the host inflammatory response. Here, this review provides an overview of P. gingivalis and how its virulence factors contribute to the pathogenesis with other microbiome consortium in oral cavity.
    Matched MeSH terms: Virulence Factors
  5. Fulltext The mazEF toxin-antitoxin system as an attractive target in clinical isolates of Enterococcus faecium and Enterococcus faecalis
    Soheili S, Ghafourian S, Sekawi Z, Neela VK, Sadeghifard N, Taherikalani M, et al.
    Drug Des Devel Ther, 2015;9:2553-61.
    PMID: 26005332 DOI: 10.2147/DDDT.S77263
    The toxin-antitoxin (TA) system is a regulatory system where two sets of genes encode the toxin and its corresponding antitoxin. In this study, the prevalence of TA systems in independently isolated clinical isolates of Enterococcus faecium and Enterococcus faecalis was determined, the dominant TA system was identified, different virulence genes in E. faecium and E. faecalis were surveyed, the level of expression of the virulence and TA genes in normal and stress conditions was determined, and finally their associations with the TA genes were defined. Remarkably, the analysis demonstrated higBA and mazEF in all clinical isolates, and their locations were on chromosomes and plasmids, respectively. On the other hand, a quantitative analysis of TA and virulence genes revealed that the expression level in both genes is different under normal and stress conditions. The results obtained by anti-mazF peptide nucleic acids demonstrated that the expression level of virulence genes had decreased. These findings demonstrate an association between TA systems and virulence factors. The mazEF on the plasmids and the higBA TA genes on the chromosomes of all E. faecium and E. faecalis strains were dominant. Additionally, there was a decrease in the expression of virulence genes in the presence of anti-mazF peptide nucleic acids. Therefore, it is suggested that mazEF TA systems are potent and sensitive targets in all E. faecium and E. faecalis strains.
    Matched MeSH terms: Virulence Factors
  6. Fulltext Conflict of interest and signal interference lead to the breakdown of honest signaling
    Popat R, Pollitt EJ, Harrison F, Naghra H, Hong KW, Chan KG, et al.
    Evolution, 2015 Sep;69(9):2371-83.
    PMID: 26282874 DOI: 10.1111/evo.12751
    Animals use signals to coordinate a wide range of behaviors, from feeding offspring to predator avoidance. This poses an evolutionary problem, because individuals could potentially signal dishonestly to coerce others into behaving in ways that benefit the signaler. Theory suggests that honest signaling is favored when individuals share a common interest and signals carry reliable information. Here, we exploit the opportunities offered by bacterial signaling to test these predictions with an experimental evolution approach. We show that: (1) reduced relatedness leads to the relative breakdown of signaling, (2) signaling breaks down by the invasion of mutants that show both reduced signaling and reduced response to signal, (3) the genetic route to signaling breakdown is variable, and (4) the addition of artificial signal, to interfere with signal information, also leads to reduced signaling. Our results provide clear support for signaling theory, but we did not find evidence for previously predicted coercion at intermediate relatedness, suggesting that mechanistic details can alter the qualitative nature of specific predictions. Furthermore, populations evolved under low relatedness caused less mortality to insect hosts, showing how signal evolution in bacterial pathogens can drive the evolution of virulence in the opposite direction to that often predicted by theory.
    Matched MeSH terms: Virulence
  7. Fulltext Variable Responses to Carbon Utilization between Planktonic and Biofilm Cells of a Human Carrier Strain of Salmonella enterica Serovar Typhi
    Kalai Chelvam K, Yap KP, Chai LC, Thong KL
    PLoS One, 2015;10(5):e0126207.
    PMID: 25946205 DOI: 10.1371/journal.pone.0126207
    Salmonella enterica serovar Typhi (S. Typhi) is a foodborne pathogen that causes typhoid fever and infects only humans. The ability of S. Typhi to survive outside the human host remains unclear, particularly in human carrier strains. In this study, we have investigated the catabolic activity of a human carrier S. Typhi strain in both planktonic and biofilm cells using the high-throughput Biolog Phenotype MicroArray, Minimum Biofilm Eradication Concentration (MBEC) biofilm inoculator (96-well peg lid) and whole genome sequence data. Additional strains of S. Typhi were tested to further validate the variation of catabolism in selected carbon substrates in the different bacterial growth phases. The analyzes of the carbon utilization data indicated that planktonic cells of the carrier strain, S. Typhi CR0044 could utilize a broader range of carbon substrates compared to biofilm cells. Pyruvic acid and succinic acid which are related to energy metabolism were actively catabolised in the planktonic stage compared to biofilm stage. On the other hand, glycerol, L-fucose, L-rhamnose (carbohydrates) and D-threonine (amino acid) were more actively catabolised by biofilm cells compared to planktonic cells. Notably, dextrin and pectin could induce strong biofilm formation in the human carrier strain of S. Typhi. However, pectin could not induce formation of biofilm in the other S. Typhi strains. Phenome data showed the utilization of certain carbon substrates which was supported by the presence of the catabolism-associated genes in S. Typhi CR0044. In conclusion, the findings showed the differential carbon utilization between planktonic and biofilm cells of a S. Typhi human carrier strain. The differences found in the carbon utilization profiles suggested that S. Typhi uses substrates mainly found in the human biliary mucus glycoprotein, gallbladder, liver and cortex of the kidney of the human host. The observed diversity in the carbon catabolism profiles among different S. Typhi strains has suggested the possible involvement of various metabolic pathways that might be related to the virulence and pathogenesis of this host-restricted human pathogen. The data serve as a caveat for future in-vivo studies to investigate the carbon metabolic activity to the pathogenesis of S. Typhi.
    Matched MeSH terms: Virulence
  8. Strain differences in Blastocystis isolates as detected by a single set of polymerase chain reaction primers
    Init I, Mak JW, Lokman Hakim S, Yong HS
    Parasitol Res, 1999 Feb;85(2):131-4.
    PMID: 9934962
    A total of 20 isolates of Blastocystis were characterized using a single set of polymerase chain reaction (PCR) primers. The amplification product revealed five types of pattern. All four isolates from Singapore yielded PCR products quite different from those of the local isolates. However, most of the local isolates showed a major product at either 280 or 500 bp, or both. We also suspected that the amplification product detected at 280 bp might be an indicator of the pathogenicity of this parasite. One isolate (M12) obtained from a monkey showed patterns similar to those of human isolates (10203 and KP1) and probably belongs to the same strain. The results indicate that the intraspecific or interstrain variations in these 20 Blastocystis isolates belong to 5 different patterns. The differences among isolates of the same strain revealed by the presence or absence of certain amplification products showed further intrastrain variations in this parasite.
    Matched MeSH terms: Virulence
  9. Demonstration of an antigenic protein specific for Salmonella typhi
    Ismail A, Hai OK, Kader ZA
    Biochem Biophys Res Commun, 1991 Nov 27;181(1):301-5.
    PMID: 1958200
    Current studies were undertaken to determine the presence of a specific antigenic protein on the outer membrane of Salmonella typhi. Immunoblot analysis using sera from patients with fevers revealed that the 50 kD band was specifically recognized only by typhoid sera. The 50 kD band located on the outer membrane is protein by nature and is not a Vi (capsular), dH (flagellar), or O9 (somatic) antigen of S. typhi. These results indicate the usefulness of the specific antigen in the development of a serodiagnostic test for typhoid fever since antibodies of both the IgM and IgG class responses were obtained.
    Matched MeSH terms: Virulence
  10. Attenuation of virulence of flaviviruses following passage in HeLa cells
    Dunster LM, Gibson CA, Stephenson JR, Minor PD, Barrett AD
    J Gen Virol, 1990 Mar;71 ( Pt 3):601-7.
    PMID: 2155996
    The ability of passage in HeLa cells to attenuate flaviviruses was investigated for three different strains of the mosquito-borne West Nile (WN) virus and two tick-borne viruses, louping-ill and Langat. One strain of WN virus, Sarawak, was attenuated 4000-fold for adult mice by intraperitoneal or intranasal challenge after six HeLa passages. The HeLa-passaged virus was also found to be antigenically different and temperature-sensitive in its growth characteristics compared with the parent. After six HeLa cell passages the Egypt 101 and Smithburn strains of WN virus lost their ability to infect monkey kidney cells and no longer killed adult mice, although inoculated animals became sick for several days. In contrast, two tick-borne flaviviruses remained as virulent for mice after six HeLa passages as the parent non-HeLa-passaged virus. Neither of the tick-borne viruses exhibited characteristics associated with temperature sensitivity. The results, therefore, indicate that the mosquito-borne, but not tick-borne, flaviviruses can be attenuated by very few passages in HeLa cells. This observation may provide a model system with which to analyse the molecular basis of attenuation and/or virulence of mosquito-borne flaviviruses.
    Matched MeSH terms: Virulence
  11. Neurovirulence of four encephalitogenic dengue 3 virus strains isolated in Malaysia (1992-1994) is not attributed to their envelope protein
    Fong MY, Yusup R, Yusof R, Lam SK
    Trans R Soc Trop Med Hyg, 2004 Jun;98(6):379-81.
    PMID: 15099995
    The amino acid sequences of the envelope (E) protein of four encephalitogenic and five non-encephalitogenic dengue 3 virus strains isolated in Malaysia were determined and compared. Multiple sequence alignment revealed a high degree of similarity in the E protein of the strains suggesting that neurovirulence of these four encephalitogenic strains is not attributed to this protein.
    Matched MeSH terms: Virulence
  12. Fulltext A review on rhodococcus equi: horse, cat and human
    Aslam, M.W.
    Jurnal Veterinar Malaysia, 2019;31(2):1-12.
    MyJurnal
    In recent years, Rhodococcus equi has emerged as pathogen of importance in respiratory and non-respiratory infectious diseases of animals and humans. Its distribution is worldwide and incidence of disease is increasing in nonequine species like cats and humans. Sporadic infection in human and cat is hypothesized to infect immunocompromised cases largely. While predominantly in foals, infection is quite endemic/epidemic in nature depending on virulence of strain, and incidence is 10 – 20% since birth till weaning. Mode of acquisition is quite variable in humans, cats and foals and depends on the route of exposure. Pathogenesis is well understood in natural host but in cats and humans it is still in its infancy because of the manifestation of unusual cases with low to no exposure to contaminated elements. Clinical signs depend on the site of infection but respiratory manifestations are quite common in foals and human cases. In cats extra-pulmonary disorders are hypothesized as more common presentation. Definitive diagnosis is based on the microbiological culture and cytology from tracheobronchial aspirate for respiratory cases and site of sample for non-respiratory lesions. White blood cells and fibrinogen have some correlation in degree of diagnosis in foals but not in cats and humans. Macrolides especially clarithromycin along with rifampin are considered best combination at the moment and recently resistance is being reported against erythromycin and rifampin. In foals, consensus statements by ACVIM published detailed control and preventions but in humans and cats so far hygiene and isolation of infected patients are for the time being the methods to control nosocomial spread.
    Matched MeSH terms: Virulence
  13. In vitro assessment of pathogenicity and virulence encoding gene profiles of avian pathogenic Escherichia coli strains associated with colibacillosis in chickens
    Ugwu IC, Lee-Ching L, Ugwu CC, Okoye JOA, Chah KF
    Iran J Vet Res, 2020;21(3):180-187.
    PMID: 33178295
    Background: Avian pathogenic Escherichia coli (APEC) strains have been associated with various disease conditions in avian species due to virulence attributes associated with the organism.

    Aims: This study was carried out to determine the in vitro pathogenic characteristics and virulence encoding genes found in E. coli strains associated with colibacillosis in chickens.

    Methods: Fifty-two stock cultures of E. coli strains isolated from chickens diagnosed of colibacillosis were tested for their ability to produce haemolysis on blood agar and take up Congo red dye. Molecular characterization was carried out by polymerase chain reaction (PCR) amplification of virulence encoding genes associated with APEC.

    Results: Eleven (22%) and 41 (71%) were positive for haemolysis on 5% sheep red blood agar and Congo red agar, respectively. Nine virulence-associated genes were detected as follows: FimH (96%), csgA (52%), iss (48%), iut (33%), tsh (21%), cva (15%), kpsII (10%), pap (2%), and felA (2%).

    Conclusion: The APEC strains exhibited virulence properties and harbored virulence encoding genes which could be a threat to the poultry population and public health. The putative virulence genes were diverse and different in almost all isolate implying that pathogenesis was multi-factorial and the infection was multi-faceted which could be a source of concern in the detection and control of APEC infections.

    Matched MeSH terms: Virulence
  14. Fulltext Dairy Cattle, a Potential Reservoir of Human Campylobacteriosis: Epidemiological and Molecular Characterization of Campylobacter jejuni From Cattle Farms
    An JU, Ho H, Kim J, Kim WH, Kim J, Lee S, et al.
    Front Microbiol, 2018;9:3136.
    PMID: 30619204 DOI: 10.3389/fmicb.2018.03136
    Campylobacter jejuni is a major foodborne pathogen that is increasingly found worldwide and that is transmitted to humans through meat or dairy products. A detailed understanding of the prevalence and characteristics of C. jejuni in dairy cattle farms, which are likely to become sources of contamination, is imperative and is currently lacking. In this study, a total of 295 dairy cattle farm samples from 15 farms (24 visits) in Korea were collected. C. jejuni prevalence at the farm level was 60% (9/15) and at the animal level was 23.8% (68/266). Using the multivariable generalized estimating equation (GEE) model based on farm-environmental factors, we estimated that a high density of cattle and average environmental temperature (7 days prior to sampling) below 24°C affects the presence and survival of C. jejuni in the farm environment. Cattle isolates, together with C. jejuni from other sources (chicken and human), were genetically characterized based on analysis of 10 virulence and survival genes. A total of 19 virulence profile types were identified, with type 01 carrying eight genes (all except hcp and virB11) being the most prevalent. The prevalence of virB11 and hcp was significantly higher in isolates from cattle than in those from other sources (p < 0.05). Multilocus sequence typing (MLST) of C. jejuni isolates from three different sources mainly clustered in the CC-21 and CC-48. Within the CC-21 and CC-48 clusters, cattle isolates shared an indistinguishable pattern with human isolates according to pulsed-field gel electrophoresis (PFGE) and flaA-restriction fragment length polymorphism (RFLP) typing. This suggests that CC-21 and CC-48 C. jejuni from dairy cattle are genetically related to clinical campylobacteriosis isolates. In conclusion, the farm environment influences the presence and survival of C. jejuni, which may play an important role in cycles of cattle re-infection, and dairy cattle represent potential reservoirs of human campylobacteriosis. Thus, environmental management practices could be implemented on cattle farms to reduce the shedding of C. jejuni from cattle, subsequently reducing the potential risk of the spread of cattle-derived C. jejuni to humans through the food chain.
    Matched MeSH terms: Virulence
  15. Iron-associated protein interaction networks reveal the key functional modules related to survival and virulence of Pasteurella multocida
    Jatuponwiphat T, Chumnanpuen P, Othman S, E-Kobon T, Vongsangnak W
    Microb Pathog, 2019 Feb;127:257-266.
    PMID: 30550841 DOI: 10.1016/j.micpath.2018.12.013
    Pasteurella multocida causes respiratory infectious diseases in a multitude of birds and mammals. A number of virulence-associated genes were reported across different strains of P. multocida, including those involved in the iron transport and metabolism. Comparative iron-associated genes of P. multocida among different animal hosts towards their interaction networks have not been fully revealed. Therefore, this study aimed to identify the iron-associated genes from core- and pan-genomes of fourteen P. multocida strains and to construct iron-associated protein interaction networks using genome-scale network analysis which might be associated with the virulence. Results showed that these fourteen strains had 1587 genes in the core-genome and 3400 genes constituting their pan-genome. Out of these, 2651 genes associated with iron transport and metabolism were selected to construct the protein interaction networks and 361 genes were incorporated into the iron-associated protein interaction network (iPIN) consisting of nine different iron-associated functional modules. After comparing with the virulence factor database (VFDB), 21 virulence-associated proteins were determined and 11 of these belonged to the heme biosynthesis module. From this study, the core heme biosynthesis module and the core outer membrane hemoglobin receptor HgbA were proposed as candidate targets to design novel antibiotics and vaccines for preventing pasteurellosis across the serotypes or animal hosts for enhanced precision agriculture to ensure sustainability in food security.
    Matched MeSH terms: Virulence
  16. Pilus islets and the clonal spread of piliated Streptococcus pneumoniae: A review
    Dzaraly ND, Muthanna A, Mohd Desa MN, Taib NM, Masri SN, Rahman NIA, et al.
    Int J Med Microbiol, 2020 Oct;310(7):151449.
    PMID: 33092697 DOI: 10.1016/j.ijmm.2020.151449
    Pneumococci are a common cause of severe infections, such as otitis media, pneumonia, meningitis and bacteremia. Pili are detected in a small proportion of pneumococcal population, but these structures have recently been associated with bacterial virulence in humans. Therefore, the epidemiological relationships between pneumococcal pili, serotype and antimicrobial resistance are of interest. This study aims to discuss the virulence contribution of the Streptococcus pneumoniae pili and the epidemiological relationships among the pilus genes, antimicrobial resistance trends, regional serotypes and genotypic variations. Previous reports have characterized the pneumococcal pilus islet as a clonal feature in the pneumococcal serotypes that are covered by the pneumococcal conjugate vaccine (PCV), including serotypes 19A, 19F, 23F and 7F. Many of the pneumococcal molecular epidemiology network (PMEN) clones are piliated isolates that are also strongly associated with a high frequency of multidrug resistance. Most of these piliated pneumococcal isolates belong to a few clonal complexes (CC), such as CC320, CC199, CC271, CC191 and CC156. Additional molecular epidemiology and genomic studies, particularly whole genome sequence analysis (WGS), are needed to develop an in-depth understanding of the piliated pneumococcal isolates.
    Matched MeSH terms: Virulence
  17. Fulltext Bioactive Compounds from the Bornean Endemic Plant Goniothalamus longistipetes
    Teo SP, Bhakta S, Stapleton P, Gibbons S
    Antibiotics (Basel), 2020 Dec 16;9(12).
    PMID: 33339285 DOI: 10.3390/antibiotics9120913
    The present study aimed to screen plants for bioactive compounds with potential antibacterial activities. In our efforts to evaluate plants from Borneo, we isolated and elucidated the structures of four natural products from the bioactive fraction of a chloroform extract of Goniothalamus longistipetes using various chromatographic and spectroscopic techniques. The bioactive compounds were identified as a known styryllactone, (+)-altholactone ((2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (1), a new styryllactone, (2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (2) as well as a new alkaloid, 2,6-dimethoxyisonicotinaldehyde (3) and a new alkenyl-5-hydroxyl-phenyl benzoic acid (4). 1 and 4 showed broad-spectrum anti-bacterial activities against Gram-positive and Gram-negative bacteria as well as acid-fast model selected for this study. Compound 2 only demonstrated activities against Gram-positive bacteria whilst 3 displayed selective inhibitory activities against Gram-positive bacterial strains. Additionally, their mechanisms of anti-bacterial action were also investigated. Using Mycobacterium smegmatis as a fast-growing model of tubercle bacilli, compounds 1, 2 and 4 demonstrated inhibitory activities against whole-cell drug efflux and biofilm formation; two key intrinsic mechanisms of antibiotic resistance. Interestingly, the amphiphilic compound 4 exhibited inhibitory activity against the conjugation of plasmid pKM101 in Escherichia coli using a plate conjugation assay. Plasmid conjugation is a mechanism by which Gram-positive and Gram-negative-bacteria acquire drug resistance and virulence. These results indicated that bioactive compounds isolated from Goniothalamus longistipetes can be potential candidates as 'hits' for further optimisation.
    Matched MeSH terms: Virulence
  18. Fulltext Pathogenicity of leptospira icterohaemorrhagiae serovar lai strain Langkawi in guinea pigs (cavia porcellus)
    Tyagita, H., Bahaman, A.R., Jasni, S., Ibrahim, T.A.T., Fuzina, N.H.
    Jurnal Veterinar Malaysia, 2019;31(1):1-11.
    MyJurnal
    A tourist was infected with a new strain of leptospires namely, Leptospira icterohemorrhagiae serovar Lai strain Langkawi, when he was on vacation in Langkawi, Malaysia. The leptospiral strain was successfully isolated from the patient in the Netherland. In this study, the bacteria were retrieved from Holland and inoculated into fifteen guinea pigs in Universiti Putra Malaysia (UPM) to determine its pathogenicity. The main clinical symptoms in the guinea pigs were decreased appetite and jaundice. Blood profile showed high neutrophil, lymphocyte, PCV, RBC, haemoglobin, leukocyte and thrombocyte counts. Besides that, enhancement of electrolytes such as sodium (Na), chloride (Cl), and potassium (K) was also noted. Biochemical examination showed an increase alkaline phosphatase (ALP), aspartate transaminase (AST) and bilirubin levels. Albumin, alanine transaminase (ALT), blood urea, total protein and creatinine were low values. Histopathological examination under haematoxylin and eosin staining showed evidence of haemorrhages, congestion and oedema in all organs, with inflammatory cell infiltration characterized by neutrophils, lymphocytes and macrophages. Hydropic degeneration and cell necrosis were also common in the findings. Leptospires were detected from Day 2 p.i by silver staining and transmission electron microscopy (TEM). Rise in antibody titre was seen as early as Day 5 p.i and leptospiral DNA was detected by PCR in the kidneys and liver on Day 3 and Day 5, respectively. The findings were indicative of leptospirosis. This study demonstrated that guinea pigs are a suitable animal model to illustrate the clinical symptoms and pathological changes seen following infection with Leptospira icterohaemorrhagiae serovar Lai strain Langkawi. In general, the symptoms and changes seen in leptospirosis are similar to viral infections and the information and data from this present study would help differentiate infection due to leptospires from that of viral infection. Leptospiral infection has often been misdiagnosed to be viral infection such as influenza and dengue which have similar signs and symptoms as leptospirosis.
    Matched MeSH terms: Virulence
  19. Fulltext Expression, purification and characterization of the dimeric protruding domain of Macrobrachium rosenbergii nodavirus capsid protein expressed in Escherichia coli
    Chong LC, Ganesan H, Yong CY, Tan WS, Ho KL
    PLoS One, 2019;14(2):e0211740.
    PMID: 30707739 DOI: 10.1371/journal.pone.0211740
    Macrobrachium rosenbergii nodavirus (MrNV) is the causative agent of white tail disease (WTD) which seriously impedes the production of the giant freshwater prawn and has a major economic impact. MrNV contains two segmented RNA molecules, which encode the RNA dependent RNA polymerase (RdRp) and the capsid protein (MrNV-CP) containing 371 amino acid residues. MrNV-CP comprises of the Shell (S) and the Protruding (P) domains, ranging from amino acid residues 1-252 and 253-371, respectively. The P-domain assembles into dimeric protruding spikes, and it is believed to be involved in host cell attachment and internalization. In this study, the recombinant P-domain of MrNV-CP was successfully cloned and expressed in Escherichia coli, purified with an immobilized metal affinity chromatography (IMAC) and size exclusion chromatography (SEC) up to ~90% purity. Characterization of the purified recombinant P-domain with SEC revealed that it formed dimers, and dynamic light scattering (DLS) analysis demonstrated that the hydrodynamic diameter of the dimers was ~6 nm. Circular dichroism (CD) analysis showed that the P-domain contained 67.9% of beta-sheets, but without alpha-helical structures. This is in good agreement with the cryo-electron microscopic analysis of MrNV which demonstrated that the P-domain contains only beta-stranded structures. Our findings of this study provide essential information for the production of the P-domain of MrNV-CP that will aid future studies particularly studies that will shed light on anti-viral drug discovery and provide an understanding of virus-host interactions and the viral pathogenicity.
    Matched MeSH terms: Virulence
  20. First Report of Pod and Stem Blight of Lima Bean Caused by Diaporthe phaseolorum var. sojae in Malaysia
    Mahmodi F, Kadir JB, Puteh A, Wong MY, Nasehi A
    Plant Dis, 2013 Feb;97(2):287.
    PMID: 30722331 DOI: 10.1094/PDIS-08-12-0756-PDN
    In July 2011, a severe outbreak of pod and stem blight was observed on lima bean (Phaseolus lunatus L.) plants grown in the Cameron Highlands, located in Pahang State, Malaysia. Disease incidence varied from 33 to 75% in different fields. Pods and stems exhibited withered, light brown to reddish brown necrotic areas. Sub-circular and brown lesions were produced on the leaves. These lesions varied in size, often reaching a diameter of 1 to 2 cm. After tissue death, numerous pycnidia were observed on the surface of the pod or stem. The pycnidia diameter varied from 155 to 495 μm, averaging 265.45 μm, and on the surface of the pod or stem, pycnidia were often arranged concentrically or linearly, respectively. Pycnidiospores were hyaline, 1-celled, usually straight, and rarely, slightly curved. The α-spores varied from 5.5 to 9.0 × 2.5 to 4.0 μm; averaging 7.3 × 3.5 μm. The β-spores found either alone or with pycnidiospores in pycnidia were slender, hyaline, nonseptate, and straight or curved. Size varied from 15.8 to 38.0 × 1.3 to 2.1 μm; averaging 25.86 × 1.8 μm. The colony characteristics were recorded from pure cultures grown on potato dextrose agar plates, and incubated in darkness for 7 days at 25 °C, then exposed to 16/8 h light and dark periods at 25°C for a further 14 to 21 days. Morphological characteristics of the colonies and spores on PDA matched those described for P. phaseolorum var. sojae (2). Colonies were white, compact, with wavy mycelium and stromata with pycnidia that contained abundant β-spores. Sequence analysis of the ribosomal DNA internal transcribed spacer obtained from the Malaysian isolate FM1 (GenBank Accession No. JQ514150) using primers ITS5 and ITS4 (1) aligned with deposited sequences from GenBank confirmed identity and revealed 99% to 100% DNA similarity with P. phaseolorum strains (AY577815, AF001020, HM012819, JQ936148). The isolate FM1 was used for pathogenicity testing. Five non-infected detached leaves and pods of 4-week-old lima bean were surface sterilized and inoculated by placing 10 μl of conidial suspension (106 conidia ml-1) on the surface of leaves and pods using either the wound/drop or non-wound/drop method and distilled water used as control (3). The inoculated leaves and pods were incubated at 25 °C and 98% RH, and the experiment was performed twice. Disease reactions and symptoms were evaluated after inoculation. After one week, typical symptoms of pod and stem blight appeared with formation of pycnidia on the surface of the tissues, but not on non-inoculated controls. P. phaseolorum var. sojae was consistently reisolated from symptoms. To our knowledge, this is the first report of P. phaseolorum var. sojae causing pod and stem blight of lima bean in Malaysia. References: (1) R. Ford et al. Aust. Plant Pathol. 33:559, 2004. (2) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. American Phytopathological Society, St. Paul, MN, 1999. (3) P. P. Than et al. Plant Pathol. 57:562, 2008.
    Matched MeSH terms: Virulence
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