Displaying publications 1 - 20 of 444 in total

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  1. 25S rDNA genotyping and multi-locus sequence typing of Candida albicans of pathogenic and commensal origins in the Klang Valley, Malaysia
    Illyaaseen Z, Ngeow YF, Yap SF, Ng HF
    Malays J Pathol, 2021 Apr;43(1):55-61.
    PMID: 33903306
    Candida albicans is an important opportunistic fungal pathogen capable of causing fatal systemic infections in humans. Presently in Malaysia, there is little information available on the genetic diversity of this organism and trends in behavioural characteristics. In this project, three genotyping methods: 25S rDNA genotyping, Alternative Lengthening of Telomerase (ALT) sequence typing and Multi-Locus Sequence Typing (MLST) were applied to study the genetic diversity of strains from infected hospital in-patients and asymptomatic individuals in the community. The results showed that, with the 25S rDNA genotyping, as in other parts of the world, the most common genotype was type A which accounted for approximately 70% of the 111 isolates tested. Further typing with the ALT sequence showed type 3 to be the most common in the isolates tested. MLST analysis revealed many possibly novel sequence types, as well as a statistically significant association between pathogenicity and a group of closely related isolates, most of which were from hospital samples. Further work on genotypes associated with enhanced virulence will help to clarify the value of genotyping for clinical and epidemiological investigations.
    Matched MeSH terms: Virulence
  2. A case of human infection with Newcastle disease virus
    Mustaffa-Babjee A, Ibrahim AL, Khim TS
    Southeast Asian J. Trop. Med. Public Health, 1976 Dec;7(4):622-4.
    PMID: 1025751
    A case of Newcastle disease virus infection in a female laboratory technician is reported for the first time in Malaysia. Infection was acquired by droplet infection of the eye while grinding infected chicken in the laboratory. The case was confirmed by isolation of Newcastle disease virus from an eye swab taken from the subject on the first day of clinical signs. A four-fold rise of haemagglutination-inhibition titre was shown when sera on the third day of infection and 15 days later were compared.
    Matched MeSH terms: Virulence
  3. Fulltext A decade of sustained selection pressure on two surface sites of the VP1 protein of Enterovirus A71 suggests that immune evasion may be an indirect driver for virulence
    Roberts R, Yee PTI, Mujawar S, Lahiri C, Poh CL, Gatherer D
    Sci Rep, 2019 04 01;9(1):5427.
    PMID: 30931960 DOI: 10.1038/s41598-019-41662-8
    Enterovirus A71 (EV-A71) is an emerging pathogen in the Enterovirus A species group. EV-A71 causes hand, foot and mouth disease (HFMD), with virulent variants exhibiting polio-like acute flaccid paralysis and other central nervous system manifestations. We analysed all enterovirus A71 complete genomes with collection dates from 2008 to mid-2018. All sub-genotypes exhibit a strong molecular clock with omega (dN/dS) suggesting strong purifying selection. In sub-genotypes B5 and C4, positive selection can be detected at two surface sites on the VP1 protein, also detected in positive selection studies performed prior to 2008. Toggling of a limited repertoire of amino acids at these positively selected residues over the last decade suggests that EV-A71 may be undergoing a sustained frequency-dependent selection process for immune evasion, raising issues for vaccine development. These same sites have also been previously implicated in virus-host binding and strain-associated severity of HFMD, suggesting that immune evasion may be an indirect driver for virulence (154 words).
    Matched MeSH terms: Virulence*
  4. A linking bridge between histopathological analysis and molecular assay in microbiology
    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
  5. Fulltext A novel goose-origin Tembusu virus exhibits pathogenicity in day-old chicks with evidence of direct contact transmission
    Liu M, Chen YY, Twu NC, Wu MC, Fang ZS, Dubruel A, et al.
    Poult Sci, 2024 Feb;103(2):103332.
    PMID: 38128459 DOI: 10.1016/j.psj.2023.103332
    In late 2020, an outbreak of Tembusu virus (TMUV)-associated disease occurred in a 45-day-old white Roman geese flock in Taiwan. Here, we present the identification and isolation of a novel goose-origin TMUV strain designated as NTU/C225/2020. The virus was successfully isolated using minimal-pathogen-free duck embryos. Phylogenetic analysis of the polyprotein gene showed that NTU/C225/2020 clustered together with the earliest isolates from Malaysia and was most closely related to the first Taiwanese TMUV strain, TP1906. Genomic analysis revealed significant amino acid variations among TMUV isolates in NS1 and NS2A protein regions. In the present study, we characterized the NTU/C225/2020 culture in duck embryos, chicken embryos, primary duck embryonated fibroblasts, and DF-1 cells. All host systems were susceptible to NTU/C225/2020 infection, with observable lesions. In addition, animal experiments showed that the intramuscular inoculation of NTU/C225/2020 resulted in growth retardation and hyperthermia in day-old chicks. Gross lesions in the infected chicks included hepatomegaly, hyperemic thymus, and splenomegaly. Viral loads and histopathological damage were displayed in various tissues of both inoculated and naïve co-housed chicks, confirming the direct chick-to-chick contact transmission of TMUV. This is the first in vivo study of a local TMUV strain in Taiwan. Our findings provide essential information for TMUV propagation and suggest a potential risk of disease outbreak in chicken populations.
    Matched MeSH terms: Virulence
  6. Fulltext A rare case of Ralstonia mannitolilytica infection in an end stage renal patient on maintenance dialysis during municipal water contamination
    Lim CTS, Lee SE
    Pak J Med Sci, 2017 10 27;33(4):1047-1049.
    PMID: 29067090 DOI: 10.12669/pjms.334.13112
    Ralstonia mannitolilytica is a gram negative soil bacterium. Ralstonia infection though rare, has become the emerging nosocomial pathogens in hospital settings. Various clinical manifestations had been described as well as the mode of transmission. Despite its low virulence factor, it is able to survive under harsh condition and this may potentially cause significant morbidity and mortality especially in immunocompromised patients. Outbreak of Ralstonia mannitolilytica infections in the hospital are typically associated with contaminated medical supplies or instruments. We described here a case of Ralstonia mannitolilytica infection in a dialysis patient that occurred during the municipal reservoir water contamination crisis. In this report, we will also describe the behaviour of Ralstonia genus and its 4 main species, namely R. pickettii, R. solanacearum, R. insidiosa, and R. mannitolilytica and the choices of antibiotic therapy based on literature review.
    Matched MeSH terms: Virulence Factors
  7. 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
  8. A review on the origin of multidrug-resistant Salmonella and perspective of tailored phoP gene towards avirulence
    Gangathraprabhu B, Kannan S, Santhanam G, Suryadevara N, Maruthamuthu M
    Microb Pathog, 2020 Oct;147:104352.
    PMID: 32592823 DOI: 10.1016/j.micpath.2020.104352
    Salmonellosis continues to remain a health problem as the causative organism Salmonella spp. developed resistance to many of the antibiotics. As per World Health Organization (WHO), it is estimated that enteric fever, accounts for almost 16 million cases annually and over 600,000 deaths worldwide. Recent data revealed that the multi-drug resistance (MDR) rate of enteric fever was as high as 70% in Asian countries, as compared with the overall reported incidence of 50%. Emergence of MDR typhoid fever demands the use of newer antibiotics which also not offer promising effect in recent days. Effective antimicrobial therapy is required to control morbidity and prevent death from typhoid fever. The studies on PhoP/Q regulation revealed it as a best-characterized transcriptional regulation; a two-component system required for Salmonella pathogenesis which controls the expression of more than 40 genes. The PhoP DNA binding proteins possess positively charged amino acids such as arginine, lysine and histidine which present in the DNA binding site. Prevention of PhoP binding in phoP box may ultimately prevent the expression of many regulatory mechanism which plays vital role in Salmonella virulence. Deepness study of PhoP protein and various mutation swots may offer effectual controlling of MDR Salmonella.
    Matched MeSH terms: Virulence
  9. ACE2 role in SARS-CoV-2 infectivity and Covid-19 severity
    Azizan E, Brown M
    Malays J Pathol, 2020 Dec;42(3):363-367.
    PMID: 33361716
    In 2003, it was discovered that the entry receptor for the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) is a protein called the angiotensin-converting enzyme 2 (ACE2). This protein is present in a number of cell types, including those from the respiratory tract. Soon after the emergence of SARS-CoV-2 that is responsible for the disease Covid-19, scientists found that ACE2 was also used by the new coronavirus to infect cells. This opened some interesting possibilities to explain the striking variation in risks of catching and dying from Covid-19. The best recognised of these are the much higher risk of serious illness in older than younger people, in men than women, and in those with pre-existing comorbidities such as hypertension and cardiovascular diseases. There are several ways in which the ACE2 protein might contribute to this variation. The most obvious would be if there is more ACE2, there would be more entry points for the virus to infect the cell, e.g. in older people or in men. However, the evidence for this is rather small, partly because it is not that easy to obtain representative healthy tissues. Alternatively, it could be related to ACE2 membership of a family of proteins that has one end of the protein anchored inside the cell while most of the protein protrudes from the outside of the cell which therefore can be shed when cleaved by proteases at the cell membrane. Herein we review current evidence and theories of ACE2 role on SARS-CoV-2 infectivity and Covid-19 severity.
    Matched MeSH terms: Virulence
  10. Fulltext Ability of Acanthamoeba cyst to excyst at different temperatures
    Nurul Fariza Rossle, Mohamed Kamel Abd Ghani, Anisah Nordin, Yusof Suboh, Noraina Ab Rahim
    Jurnal Sains Kesihatan Malaysia, 2011;9(1):41-43.
    MyJurnal
    This study was carried out to observe thermotolerance ability of Acanthamoeba spp. A total of 32 Acanthamoeba spp. isolates obtained from water taps, sinks, swimming pools and sea water were used. Trophozoites of Acanthamoeba spp. were inoculated onto non-nutrient agar (NNA) seeded with heat-killed Escherichia coli using aseptic technique and incubated for 14 days at 30°C to obtain the cyst. The cysts were subcultured onto new agar plates for thermotolerance test at 37°C and 42°C. The plates were observed until 96 hours after incubation for excystation of Acanthamoeba before being declared negative. Overall, 81.25% of samples were able to excyst at 37°C while 37.5% were able to excyst at 42°C. Thermotolerant Acanthamoeba is associated with high pathogenicity potential.
    Matched MeSH terms: Virulence
  11. Fulltext Acanthamoeba-mediated cytopathic effect correlates with MBP and AhLBP mRNA expression
    Ng SL, Nordin A, Abd Ghafar N, Suboh Y, Ab Rahim N, Chua KH
    Parasit Vectors, 2017 12 28;10(1):625.
    PMID: 29282148 DOI: 10.1186/s13071-017-2547-0
    BACKGROUND: In recent years, the concern of Acanthamoeba keratitis has increased since the infection is often associated with contact lens use. Partial 18S rRNA genotypic identification of Acanthamoeba isolates is important to correlate with pathophysiological properties in order to evaluate the degree of virulence. This is the first report of genotypic identification for clinical isolates of Acanthamoeba from corneal scrapings of keratitis in Malaysia. This study is also the first to correlate the mRNA expression of MBP and AhLBP as virulent markers for axenic strains of Acanthamoeba.

    RESULTS: In this study, ten clinical isolates were obtained from corneal scrapings. Rns genotype and intra-genotypic variation at the DF3 region of the isolates were identified. Results revealed that all clinical isolates belonged to the T4 genotype, with T4/6 (4 isolates), T4/2 (3 isolates), T4/16 (2 isolates) and one new genotype T4 sequence (T4/36), being determined. The axenic clinical isolates were cytopathogenic to rabbit corneal fibroblasts. MBP and AhLBP mRNA expression are directly correlated to Acanthamoeba cytopathic effect.

    CONCLUSIONS: All ten Malaysian clinical isolates were identified as genotype T4 which is predominantly associated with AK. Measuring the mRNA expression of Acanthamoeba virulent markers could be useful in the understanding of the pathogenesis of Acanthamoeba keratitis.

    Matched MeSH terms: Virulence
  12. Fulltext Acinetobacter baumannii in suspected bacterial infections: Association between multidrug resistance, virulence genes, & biofilm production
    Gautam D, Dolma KG, Khandelwal B, Goyal RK, Mitsuwan W, Pereira MLG, et al.
    Indian J Med Res, 2023 Oct 01;158(4):439-446.
    PMID: 38006347 DOI: 10.4103/ijmr.ijmr_3470_21
    BACKGROUND OBJECTIVES: Acinetobacter baumannii has emerged as a nosocomial pathogen with a tendency of high antibiotic resistance and biofilm production. This study aimed to determine the occurrence of A. baumannii from different clinical specimens of suspected bacterial infections and furthermore to see the association of biofilm production with multidrug resistance and expression of virulence factor genes in A. baumannii.

    METHODS: A. baumannii was confirmed in clinical specimens by the detection of the blaOXA-51-like gene. Biofilm production was tested by microtitre plate assay and virulence genes were detected by real-time PCR.

    RESULTS: A. baumannii was isolated from a total of 307 clinical specimens. The isolate which showed the highest number of A. baumannii was an endotracheal tube specimen (44.95%), then sputum (19.54%), followed by pus (17.26%), urine (7.49%) and blood (5.86%), and <2 per cent from body fluids, catheter-tips and urogenital specimens. A resistance rate of 70-81.43 per cent against all antibiotics tested, except colistin and tigecycline, was noted, and 242 (78.82%) isolates were multidrug-resistant (MDR). Biofilm was detected in 205 (66.78%) with a distribution of 54.1 per cent weak, 10.42 per cent medium and 2.28 per cent strong biofilms. 71.07 per cent of MDR isolates produce biofilm (P<0.05). Amongst virulence factor genes, 281 (91.53%) outer membrane protein A (OmpA) and 98 (31.92%) biofilm-associated protein (Bap) were detected. Amongst 100 carbapenem-resistant A. baumannii, the blaOXA-23-like gene was predominant (96%), the blaOXA-58-like gene (6%) and none harboured the blaOXA-24-like gene. The metallo-β-lactamase genes blaIMP-1 (4%) and blaVIM-1(8%) were detected, and 76 per cent showed the insertion sequence ISAba1.

    INTERPRETATION CONCLUSIONS: The majority of isolates studied were from lower respiratory tract specimens. The high MDR rate and its positive association with biofilm formation indicate the nosocomial distribution of A. baumannii. The biofilm formation and the presence of Bap were not interrelated, indicating that biofilm formation was not regulated by a single factor. The MDR rate and the presence of OmpA and Bap showed a positive association (P<0.05). The isolates co-harbouring different carbapenem resistance genes were the predominant biofilm producers, which will seriously limit the therapeutic options suggesting the need for strict antimicrobial stewardship and molecular surveillance in hospitals.

    Matched MeSH terms: Virulence/genetics; Virulence Factors/genetics
  13. Active human Herpesvirus-6 infections and associated diseases
    Yadav, M.
    Malaysian Journal of Child Health, 1991;3(1):11-22.
    MyJurnal
    Human Herpesvirus-6 (HHV-6) infections are ubiquitous in human populations with an antibody prevalence of 30-85 percent in normal adults. The virus in vivo infects T-lympho-cytes, at various stages of differentiation and is cytopathic to host cell during productive infection. In culture the virus is pleiotropic for several established cell lines including T and B lymphocytes, macrophages and neural cells. Primary viral infection occurs mostly in early childhood. The saliva is the primary source of infection. The infection remains clinically silent in majority but it establishes a lifelong latent presence. However, in about 30 percent of infants, probably a varient HHV-6, causes exanthem subitum (roseola infantum). If the primary infection of HHV-6 is delayed until adolescence it is accompanied by clinical manifestation of an Epstein-Barr virus like infectious mononucleosis in some individuals. Depressed host immune functions may reactivate the latent HHV-6 infection and further aggravation of the primary disease. Since the virus is cytopathic to the host cell the presence of HHV-6 in AIDS patients and other lympholiferative disorders may increase the severity and pathogenicity of the primary disease. Antibodies to the HHV-6 are enhanced in autoimmune disorders, chronic fatigue syndrome, progressive lymphoroliferative disorders and organ transplant patients on immunosuppressive drugs therapy. While considerable basic immunovirological information has been obtained in the last 4 years, large gaps in knowledge still exist on the biologic interaction of HHV-6 with the host.
    Matched MeSH terms: Virulence
  14. Fulltext Acute haematogenous community-acquired methicillin-resistant Staphylococcus aureus osteomyelitis in an adult: case report and review of literature
    Dhanoa A, Singh VA, Mansor A, Yusof MY, Lim KT, Thong KL
    BMC Infect Dis, 2012;12:270.
    PMID: 23098162 DOI: 10.1186/1471-2334-12-270
    Methicillin-resistant Staphylococcus aureus (MRSA) has of late emerged as a cause of community-acquired infections among immunocompetent adults without risk factors. Skin and soft tissue infections represent the majority of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clinical presentations, whilst invasive and life-threatening illness like necrotizing pneumonia, necrotizing fasciitis, pyomyositis, osteomyelitis and sepsis syndrome are less common. Although more widely described in the pediatric age group, the occurrence of CA-MRSA osteomyelitis in adults is an uncommonly reported entity.
    Matched MeSH terms: Virulence Factors/genetics
  15. Adhesion and invasion attributes of Burkholderia pseudomallei are dependent on airway surface liquid and glucose concentrations in lung epithelial cells
    Mariappan V, Thimma J, Vellasamy KM, Shankar EM, Vadivelu J
    Environ Microbiol Rep, 2018 04;10(2):217-225.
    PMID: 29393577 DOI: 10.1111/1758-2229.12624
    Physiological constituents in airway surface liquids (ASL) appear to impact the adherence and invasion potentials of Burkholderia pseudomallei contributing to recrudescent melioidosis. Here, we investigated the factors present in ASL that is likely to influence bacterial adhesion and invasion leading to improved understanding of bacterial pathogenesis. Six B. pseudomallei clinical isolates from different origins were used to investigate the ability of the bacteria to adhere and invade A549 human lung epithelial cells using a system that mimics the physiological ASL with different pH, NaCl, KCl, CaCl2 and glucose concentrations. These parameters resulted in markedly differential adherence and invasion abilities of B. pseudomallei to the lung epithelial cells. The concentration of 20 mM glucose dramatically increased adherence and invasion by increasing the rate of pili formation in depiliated bacteria. Glucose significantly increased adherence and invasion of B. pseudomallei to A549 cells, and presence of NaCl, KCl and CaCl2 markedly ablated the effect despite the presence of glucose. Our data established a link between glucose, enhanced adhesion and invasion potentials of B. pseudomallei, hinting increased susceptibility of individuals with diabetes mellitus to clinical melioidosis.
    Matched MeSH terms: Virulence
  16. Alteration in apyrase enzyme attenuated virulence of Shigella flexneri
    BangaSingh KK, Nisha M, Lau HY, Ravichandran M, Salleh MZ
    Microb Pathog, 2016 Feb;91:123-8.
    PMID: 26706344 DOI: 10.1016/j.micpath.2015.12.004
    Virulence of Shigella is attributed to the genes presence in chromosome or in the megaplasmid. The apy gene which is located in the megaplasmid of Shigella species encodes for apyrase enzyme, a pathogenesis-associated enzyme causing mitochondrial damage and host cell death. In this study we constructed an apy mutant of Shigella flexneri by insertional activation using a kanamycin resistant gene cassette. The wild type apy gene of S. flexneri 2a was PCR amplified, cloned and mutated with insertion of kanamycin resistant gene cassette (aphA). The mutated construct (apy: aphA) was subcloned into a conjugative suicidal vector (pWM91) at the unique Sma1 and Sac1 sites. The mutation of the wild apy gene in the construct was confirmed by DNA sequencing. The mutated construct was introduced into wild type S. flexneri 2a by conjugation with Escherichia coli. After undergoing homologous recombination, the wild apy gene was deleted from the construct using the sucrose selection method. Non-functional activity of the apyrase enzyme in the constructed strain by colorimetric test indicated the successful mutation of the apyrase enzyme. This strain with mutated apy gene was evaluated for its protective efficacy using the guinea pig keratoconjunctivitis model. The strain was Sereny negative and it elicited a significant protection following challenge with wild S. flexneri strain. This apy mutant strain will form a base for the development of a vaccine target for shigellosis.
    Matched MeSH terms: Virulence
  17. Fulltext Amoebic forms of Blastocystis spp. - evidence for a pathogenic role
    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
  18. An Outbreak of Leaf Spot Caused by Stemphylium solani on Eggplant in Malaysia
    Nasehi A, Kadir JB, Esfahani MN, Mahmodi F, Ghadirian H, Ashtiani FA, et al.
    Plant Dis, 2013 May;97(5):689.
    PMID: 30722195 DOI: 10.1094/PDIS-10-12-0901-PDN
    In 2011, a severe gray leaf spot was observed on eggplant (Solanum melongena) in major eggplant growing areas in Malaysia, including the Pahang, Johor, and Selangor states. Disease incidence was >70% in severely infected areas of about 150 ha of eggplant greenhouses and fields examined. Symptoms initially appeared as small (1 to 5 mm diameter), brownish-black specks with concentric circles on the lower leaves. The specks then coalesced and developed into greyish-brown, necrotic lesions, which also appeared on the upper leaves. Eventually, the leaves senesced and were shed. Tissue cut from the edges of leaf spots were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterilized water, dried, and incubated on potato dextrose agar (PDA). Fungal colonies were greyish green to light brown, and produced a yellow pigment. Single, muriform, brown, oblong conidia formed at the terminal end of each conidiophore, were each 21.6 to 45.6 μm long and 11.5 to 21.6 μm wide, and contained 2 to 7 transverse and 1 to 4 longitudinal septa. The conidiophores were tan to light brown and ≤220 μm long. Based on these morphological criteria, 25 isolates of the fungus were identified as Stemphylium solani (1). To produce conidia in culture, 7-day-old single-conidial cultures were established on potato carrot agar (PCA) and V8 juice agar media under an 8-h/16-h light/dark photoperiod at 25°C (4). Further confirmation of the identification was obtained by molecular characterization in which fungal DNA was extracted and the internal transcribed spacer (ITS) region of ribosomal DNA amplified using primers ITS5 and ITS4 (2), followed by direct sequencing. A BLAST search in the NCBI database revealed that the sequence was 99% identical with published ITS sequences for two isolates of S. solani (Accession Nos. AF203451 and HQ840713). The amplified ITS region was deposited in GenBank (JQ736023). Pathogenicity testing of a representative isolate was performed on detached, 45-day-old eggplant leaves of the cv. 125066-X under laboratory conditions. Four fully expanded leaves (one wounded and two non-wounded leaflets/leaf) were placed on moist filter paper in petri dishes, and each leaflet inoculated with a 20-μl drop of a conidial suspension containing 1 × 105 conidia/ml in sterilized, distilled water (3). The leaves were wounded by applying pressure to leaf blades with the serrated edge of forceps. Four control leaves were inoculated similarly with sterilized, distilled water. Inoculated leaves were incubated in humid chambers at 25°C with 95% RH and a 12-h photoperiod. After 7 days, symptoms similar to those observed in the original fields developed on both wounded and non-wounded inoculated leaves, but not on control leaves, and S. solani was reisolated consistently from the symptoms using the same method as the original isolations. Control leaves remained asymptomatic and the fungus was not isolated from these leaves. The pathogenicity testing was repeated with similar results. To our knowledge, this is the first report of S. solani on eggplant in Malaysia. References: (1) B. S. Kim et al. Plant Pathol. J. 20:85, 2004. (2) Y. R. Mehta et al. Curr. Microbiol. 44:323, 2002. (3) B. M. Pryor and T. J. Michailides. Phytopathology 92:406, 2002. (4) E. G. Simmons. CBS Biodiv. Series 6:775, 2007.
    Matched MeSH terms: Virulence
  19. An amino acid change in nsP4 of chikungunya virus confers fitness advantage in human cell lines rather than in Aedes albopictus
    Fu JYL, Chua CL, Vythilingam I, Sulaiman WYW, Wong HV, Chan YF, et al.
    J Gen Virol, 2019 11;100(11):1541-1553.
    PMID: 31613205 DOI: 10.1099/jgv.0.001338
    Chikungunya virus (CHIKV) has caused large-scale epidemics of fever, rash and arthritis since 2004. This unprecedented re-emergence has been associated with mutations in genes encoding structural envelope proteins, providing increased fitness in the secondary vector Aedes albopictus. In the 2008-2013 CHIKV outbreaks across Southeast Asia, an R82S mutation in non-structural protein 4 (nsP4) emerged early in Malaysia or Singapore and quickly became predominant. To determine whether this nsP4-R82S mutation provides a selective advantage in host cells, which may have contributed to the epidemic, the fitness of infectious clone-derived CHIKV with wild-type nsP4-82R and mutant nsP4-82S were compared in Ae. albopictus and human cell lines. Viral infectivity, dissemination and transmission in Ae. albopictus were not affected by the mutation when the two variants were tested separately. In competition, the nsP4-82R variant showed an advantage over nsP4-82S in dissemination to the salivary glands, but only in late infection (10 days). In human rhabdomyosarcoma (RD) and embryonic kidney (HEK-293T) cell lines coinfected at a 1 : 1 ratio, wild-type nsP4-82R virus was rapidly outcompeted by nsP4-82S virus as early as one passage (3 days). In conclusion, the nsP4-R82S mutation provides a greater selective advantage in human cells than in Ae. albopictus, which may explain its apparent natural selection during CHIKV spread in Southeast Asia. This is an unusual example of a naturally occurring mutation in a non-structural protein, which may have facilitated epidemic transmission of CHIKV.
    Matched MeSH terms: Virulence Factors/genetics*
  20. Fulltext An imported case of acute melioidosis caused by ST881 Burkholderia pseudomallei
    Zong Z, Wang X, Deng Y
    Southeast Asian J. Trop. Med. Public Health, 2016 Mar;47(2):219-22.
    PMID: 27244959
    A previously healthy Chinese male working in Malaysia returned to China with high fever. A blood culture showed Burkholderia pseudomallei strain WCBP1. This isolate was sequenced, showing type, ST881, which appears to be present in Malaysia. WCP1 had unusual susceptibility to aminoglycosides and habored the Yersinia-like fimbrial gene cluster for virulence. The patient's condition deteriorated rapidly but he recovered after receiving meropenem and intensive care support. Melioidosis is a potential problem among Chinese imigrant workers with strains new to China being identified.
    Matched MeSH terms: Virulence
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