Displaying publications 221 - 240 of 1514 in total

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  1. Variation in the genome of rice tungro bacilliform virus: molecular characterization of six isolates
    Fan Z, Dahal G, Dasgupta I, Hay J, Hull R
    J Gen Virol, 1996 May;77 ( Pt 5):847-54.
    PMID: 8609480
    The DNA genomes of isolates of rice tungro bacilliform virus from Bangladesh, India, Indonesia, Malaysia and Thailand were cloned and compared with that of the type isolate from the Philippines. Restriction endonuclease maps revealed differences between the isolates and cross-hybridization showed that they fell into two groups, those from the Indian subcontinent and those from south-east Asian countries. The genomes of isolates from the Indian subcontinent contained a deletion of 64 bp when compared with those from south-east Asia. The implications of this variation are discussed.
    Matched MeSH terms: Oryza/virology*
  2. Hybridisation analysis for serum hepatitis B virus DNA
    Yap SF, Wong PW, Kenneth-Raj
    Br J Biomed Sci, 1994 Dec;51(4):336-40.
    PMID: 7756940
    A study was carried out to determine optimal assay conditions for an in-house hybridisation assay for detection of hepatitis B virus (HBV) genome in serum samples. Pre-treatment of samples, blot treatment and hybridisation conditions were found to affect assay performance. The indirect serum blot procedure was more robust and reliable than direct serum blotting. In the former, viral particles were isolated from the sample, lysed and then extracted. In comparison, no approaches to the direct serum spot method performed adequately. Sensitivity studies showed that labelling of the nucleic acid probe with dCTP was more efficient than with dATP. Using probes labelled to a specific activity of > 1 x 10(8) and an autoradiography period of about 48 h we could achieve a detection limit of < 1 pg. Specificity was achieved by use of a highly purified probe and moderately stringent hybridisation and wash conditions. Background binding was minimal and there was no non-specific binding of probe to negative control samples. Factors affecting speed of the assay were studied to identify steps that could be modified to shorten assay time without sacrificing performance. A shorter centrifugation step and the use of a high specific-activity probe permitted completion of an assay within four days.
    Matched MeSH terms: Virology/methods
  3. Mechanical transport of rotavirus by the legs and wings of Musca domestica (Diptera: Muscidae)
    Tan SW, Yap KL, Lee HL
    J Med Entomol, 1997 Sep;34(5):527-31.
    PMID: 9379457
    Factors affecting the mechanical transmission of rotavirus by the legs and wings of the housefly, Musca domestica L., were examined in a laboratory study. Rotavirus was picked up when houseflies walked on thin smears of clarified rotavirus suspensions. The addition of glycerol, which increased viscosity of the virus suspension, and particulate human feces slightly increased the proportion of flies contaminated with virus. However, the addition of glycerol greatly reduced the average number of virus particles picked up per fly, whereas feces greatly increased the number of particles. The proportion of flies with virus-contaminated legs, which transferred virus to > 1 contact surface, was increased by longer contact time with the surface and when the contact surface was agar instead of glass. Most virus particles were deposited on 1st contact with the surface. Most flies dislodged virus particles inoculated on the underside of their wings soon after the start of simulated flight. Our data indicated that the nature of the virus-suspending medium has a greater effect on the level of virus contamination than on the ability to become contaminated. The importance of walking as a mode of virus transport depends on the nature of the contact surface, the risk of the contaminated fly settling first on a surface likely to come into contact with humans, and fly numbers.
    Matched MeSH terms: Houseflies/virology*
  4. Vertical transmission of dengue
    Chye JK, Lim CT, Ng KB, Lim JM, George R, Lam SK
    Clin Infect Dis, 1997 Dec;25(6):1374-7.
    PMID: 9431381
    Dengue, an important mosquito-borne flavivirus infection, is endemic in Southeast Asia. We describe two mothers who had acute dengue 4 and 8 days before the births of their infants. One mother had worsening of her proteinuric pregnancy-induced hypertension, liver dysfunction, and coagulopathy and required multiple transfusions of whole blood, platelets, and fresh frozen plasma. Her male infant was ill at birth, developed respiratory distress and a large uncontrollable left intracerebral hemorrhage, and died of multiorgan failure on day 6 of life. Dengue virus type 2 was isolated from the infant's blood, and IgM antibody specific to dengue virus was detected in the mother's blood. The second mother had a milder clinical course; she gave birth to a female infant who was thrombocytopenic at birth and had an uneventful hospitalization. Dengue virus type 2 was recovered from the mother's blood, and IgM antibody specific to dengue virus was detected in the infant's blood. This report highlights not only the apparently rare occurrence of vertical transmission of dengue virus in humans but also the potential risk of death for infected neonates.
    Matched MeSH terms: Dengue/virology
  5. Absence of rotavirus in the neonatal special care nursery of a Malaysian maternity hospital
    Yap KL, Boo NY, Surayah O
    Malays J Pathol, 1994 Jun;16(1):89-91.
    PMID: 16329583
    The pattern of rotavirus infection in babies of the neonatal special care nursery (SCN) of the Kuala Lumpur Maternity Hospital was studied. The presence of rotavirus in the neonates' stools was ascertained using the method of polyacrylamide gel electrophoresis and silver staining. No rotavirus was detected in the 511 stools and rectal swabs collected from the 164 neonates over a 8-week period. Thus the babies admitted to the SCN from the labour rooms and the postnatal wards of the hospital were unlikely to be carriers of rotavirus or infected by rotavirus during their stay. It was concluded that rotavirus was not endemic in the nursery or the postnatal wards of this maternity hospital.
    Matched MeSH terms: Feces/virology
  6. A novel approach for collecting samples from fruit bats for isolation of infectious agents
    Chua KB
    Microbes Infect., 2003 May;5(6):487-90.
    PMID: 12758277
    During the outbreak of Nipah virus encephalitis involving pigs and humans in peninsular Malaysia in 1998/1999, a conventional approach was initially undertaken to collect specimens from fruit bats by mist-netting and shooting, as an integral part of wildlife surveillance of the natural reservoir host of Nipah virus. This study describes a novel method of collecting fruit bats' urine samples using plastic sheets for isolation of Nipah virus. This novel approach resulted in the isolation of several other known and unidentified infectious agents besides Nipah virus.
    Matched MeSH terms: Chiroptera/virology*
  7. [Progress in the epidemiologic study of Nipah viral encephalitis]
    Lu XF, Wang ZG, Wang BY
    Zhonghua Liu Xing Bing Xue Za Zhi, 2004 Jun;25(6):541-3.
    PMID: 15231143
    Matched MeSH terms: Encephalitis, Viral/virology
  8. Molecular epidemiology of enterovirus 71 infection in the Western Pacific Region
    Shimizu H, Utama A, Onnimala N, Li C, Li-Bi Z, Yu-Jie M, et al.
    Pediatr Int, 2004 Apr;46(2):231-5.
    PMID: 15056257
    Recently, there have been large outbreaks of hand, foot and mouth disease (HFMD) mainly caused by enterovirus 71 (EV71) associated with severe neurological diseases in the Western Pacific Region (WPR). To monitor the realtime trend of EV71 transmission throughout the WPR, the authors conducted a molecular epidemiological analysis of EV71 infection.
    Matched MeSH terms: Hand, Foot and Mouth Disease/virology
  9. Fulltext Genomic structure and insertion sites of Helicobacter pylori prophages from various geographical origins
    Vale FF, Nunes A, Oleastro M, Gomes JP, Sampaio DA, Rocha R, et al.
    Sci Rep, 2017 02 16;7:42471.
    PMID: 28205536 DOI: 10.1038/srep42471
    Helicobacter pylori genetic diversity is known to be influenced by mobile genomic elements. Here we focused on prophages, the least characterized mobile elements of H. pylori. We present the full genomic sequences, insertion sites and phylogenetic analysis of 28 prophages found in H. pylori isolates from patients of distinct disease types, ranging from gastritis to gastric cancer, and geographic origins, covering most continents. The genome sizes of these prophages range from 22.6-33.0 Kbp, consisting of 27-39 open reading frames. A 36.6% GC was found in prophages in contrast to 39% in H. pylori genome. Remarkably a conserved integration site was found in over 50% of the cases. Nearly 40% of the prophages harbored insertion sequences (IS) previously described in H. pylori. Tandem repeats were frequently found in the intergenic region between the prophage at the 3' end and the bacterial gene. Furthermore, prophage genomes present a robust phylogeographic pattern, revealing four distinct clusters: one African, one Asian and two European prophage populations. Evidence of recombination was detected within the genome of some prophages, resulting in genome mosaics composed by different populations, which may yield additional H. pylori phenotypes.
    Matched MeSH terms: Helicobacter pylori/virology*
  10. Fulltext Detection of Wolbachia in Aedes albopictus and Their Effects on Chikungunya Virus
    Ahmad NA, Vythilingam I, Lim YAL, Zabari NZAM, Lee HL
    Am J Trop Med Hyg, 2017 Jan 11;96(1):148-156.
    PMID: 27920393 DOI: 10.4269/ajtmh.16-0516
    Wolbachia-based vector control strategies have been proposed as a means to augment the currently existing measures for controlling dengue and chikungunya vectors. Prior to utilizing Wolbachia as a novel vector control strategy, it is crucial to understand the Wolbachia-mosquito interactions. In this study, field surveys were conducted to screen for the infection status of Wolbachia in field-collected Aedes albopictus The effects of Wolbachia in its native host toward the replication and dissemination of chikungunya virus (CHIKV) was also studied. The prevalence of Wolbachia-infected field-collected Ae. albopictus was estimated to be 98.6% (N = 142) for females and 95.1% (N = 102) for males in the population studied. The Ae. albopictus were naturally infected with both wAlbA and wAlbB strains. We also found that the native Wolbachia has no impact on CHIKV infection and minimal effect on CHIKV dissemination to secondary organs.
    Matched MeSH terms: Aedes/virology*
  11. Fulltext Identification of a Newly Isolated Getah Virus in the China-Laos Border, China
    Li YY, Fu SH, Guo XF, Lei WW, Li XL, Song JD, et al.
    Biomed Environ Sci, 2017 Mar;30(3):210-214.
    PMID: 28427491 DOI: 10.3967/bes2017.028
    In this study, we isolated a virus strain (YN12031) from specimens of Armigeres subalbatus collected in the China-Laos border. BHK-21 cells infected with YN12031 exhibited an evident cytopathic effect (CPE) 32 h post-infection. The virus particles were spherical, 70 nm in diameter, and enveloped; they also featured surface fibers. Molecular genetic analysis revealed that YN12031 was closely related to alpha viruses such as Chikungunya virus and Sindbis virus, and located in the same clade as MM2021, the prototype of Getahvirus (GETV) isolated in Malaysia in 1955. Phylogenetic analysis of the E2 and capsid genes further revealed that YN12031 was located in the same clade as the Russian isolate LEIV/16275/Mag. Analysis of the homology of nucleotides and amino acids in the coding area and E2 gene demonstrated that the YN12031 isolated from the China-Laos border (tropical region) was related closest to the LEIV/16275/Mag isolate obtained in Russia (North frigid zone area) among other isolates studied. These results suggest that GETV can adapt to different geographical environments to propagate and evolve. Thus, strengthening the detection and monitoring of GETV and its related diseases is very crucial.
    Matched MeSH terms: Culicidae/virology*
  12. Nipah virus infection in bats (order Chiroptera) in peninsular Malaysia
    Yob JM, Field H, Rashdi AM, Morrissy C, van der Heide B, Rota P, et al.
    Emerg Infect Dis, 2001 May-Jun;7(3):439-41.
    PMID: 11384522
    Nipah virus, family Paramyxoviridae, caused disease in pigs and humans in peninsular Malaysia in 1998-99. Because Nipah virus appears closely related to Hendra virus, wildlife surveillance focused primarily on pteropid bats (suborder Megachiroptera), a natural host of Hendra virus in Australia. We collected 324 bats from 14 species on peninsular Malaysia. Neutralizing antibodies to Nipah virus were demonstrated in five species, suggesting widespread infection in bat populations in peninsular Malaysia.
    Matched MeSH terms: Chiroptera/virology*
  13. Experimental Nipah virus infection in pigs and cats
    Middleton DJ, Westbury HA, Morrissy CJ, van der Heide BM, Russell GM, Braun MA, et al.
    J Comp Pathol, 2002 Feb-Apr;126(2-3):124-36.
    PMID: 11945001 DOI: 10.1053/jcpa.2001.0532
    A human isolate of Nipah virus from an outbreak of febrile encephalitis in Malaysia that coincided with a field outbreak of disease in pigs was used to infect eight 6-week-old pigs orally or subcutaneously and two cats oronasally. In pigs, the virus induced a respiratory and neurological syndrome consistent with that observed in the Malaysian pigs. Not all the pigs showed clinical signs, but Nipah virus was recovered from the nose and oropharynx of both clinically and sub-clinically infected animals. Natural infection of in-contact pigs, which was readily demonstrated, appeared to be acute and self-limiting. Subclinical infections occurred in both inoculated and in-contact pigs. Respiratory and neurological disease was also produced in the cats, with recovery of virus from urine as well as from the oropharynx. The clinical and pathological syndrome induced by Nipah virus in cats was comparable with that associated with Hendra virus infection in this species, except that in fatal infection with Nipah virus there was extensive inflammation of the respiratory epithelium, associated with the presence of viral antigen. Viral shedding via the nasopharynx, as observed in pigs and cats in the present study, was not a regular feature of earlier reports of experimental Hendra virus infection in cats and horses. The findings indicate the possibility of field transmission of Nipah virus between pigs via respiratory and oropharyngeal secretions.
    Matched MeSH terms: Cat Diseases/virology; Lung/virology; Nervous System Diseases/virology; Respiratory Tract Infections/virology; Swine Diseases/virology; Trachea/virology; Respiratory Mucosa/virology
  14. Susceptibility of Culex sitiens to Japanese encephalitis virus in peninsular Malaysia
    Vythilingam I, Tan SB, Krishnasamy M
    Trop Med Int Health, 2002 Jun;7(6):539-40.
    PMID: 12031077
    The susceptibility of Culex sitiens to Japanese Encephalitis (JE) virus was examined in the laboratory. Cx. sitiens became infected with JE virus on day 8 and subsequently it is able to transmit the virus when it takes a blood meal. Both parts of the experiment were carried out using artificial membrane feeding technique.
    Matched MeSH terms: Culex/virology*
  15. Fulltext Identification and characterization of a novel Epstein-Barr Virus-encoded circular RNA from LMP-2 Gene
    Tan KE, Ng WL, Marinov GK, Yu KH, Tan LP, Liau ES, et al.
    Sci Rep, 2021 Jul 13;11(1):14392.
    PMID: 34257379 DOI: 10.1038/s41598-021-93781-w
    Epstein-Barr virus (EBV) has been recently found to generate novel circular RNAs (circRNAs) through backsplicing. However, comprehensive catalogs of EBV circRNAs in other cell lines and their functional characterization are still lacking. In this study, we have identified a list of putative EBV circRNAs in GM12878, an EBV-transformed lymphoblastoid cell line, with a significant majority encoded from the EBV latent genes. A novel EBV circRNA derived from the exon 5 of LMP-2 gene which exhibited highest prevalence, was further validated using RNase R assay and Sanger sequencing. This circRNA, which we term circLMP-2_e5, can be universally detected in a panel of EBV-positive cell lines modelling different latency programs. It ranges from lower expression in nasopharyngeal carcinoma (NPC) cells to higher expression in B cells, and is localized to both the cytoplasm and the nucleus. We provide evidence that circLMP-2_e5 is expressed concomitantly with its cognate linear LMP-2 RNA upon EBV lytic reactivation, and may be produced as a result of exon skipping, with its circularization possibly occurring without the involvement of cis elements in the short flanking introns. Furthermore, we show that circLMP-2_e5 is not involved in regulating cell proliferation, host innate immune response, its linear parental transcripts, or EBV lytic reactivation. Taken together, our study expands the current repertoire of putative EBV circRNAs, broadens our understanding of the biology of EBV circRNAs, and lays the foundation for further investigation of their function in the EBV life cycle and disease development.
    Matched MeSH terms: Epstein-Barr Virus Infections/virology
  16. Airborne transmission of SARS-CoV-2 is the dominant route of transmission: droplets and aerosols
    Rabaan AA, Al-Ahmed SH, Al-Malkey M, Alsubki R, Ezzikouri S, Al-Hababi FH, et al.
    Infez Med, 2021 03 01;29(1):10-19.
    PMID: 33664169
    Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a pandemic worldwide. On a daily basis the number of deaths associated with COVID-19 is rapidly increasing. The main transmission route of SARS-CoV-2 is through the air (airborne transmission). This review details the airborne transmission of SARS-CoV-2, the aerodynamics, and different modes of transmission (e.g. droplets, droplet nuclei, and aerosol particles). SARS-CoV-2 can be transmitted by an infected person during activities such as expiration, coughing, sneezing, and talking. During such activities and some medical procedures, aerosols and droplets contaminated with SARS-CoV-2 particles are formed. Depending on their sizes and the environmental conditions, such particles stay viable in the air for varying time periods and can cause infection in a susceptible host. Very few studies have been conducted to establish the mechanism or the aerodynamics of virus-loaded particles and droplets in causing infection. In this review we discuss the various forms in which SARS-CoV-2 virus particles can be transmitted in air and cause infections.
    Matched MeSH terms: Cough/virology
  17. Fulltext Monitoring of three-phase variations in the mortality of COVID-19 pandemic using control charts: where does Pakistan stand?
    Mahmood Y, Ishtiaq S, Khoo MBC, Teh SY, Khan H
    Int J Qual Health Care, 2021 Apr 16;33(2).
    PMID: 33822932 DOI: 10.1093/intqhc/mzab062
    BACKGROUND: At the end of December 2019, the world in general and Wuhan, the industrial hub of China, in particular, experienced the COVID-19 pandemic. Massive increment of cases and deaths occurred in China and 209 countries in Europe, America, Australia, Asia and Pakistan. Pakistan was first hit by COVID-19 when a case was reported in Karachi on 26 February 2020. Several methods were presented to model the death rate due to the COVID-19 pandemic and to forecast the pinnacle of reported deaths. Still, these methods were not used in identifying the first day when Pakistan enters or exits the early exponential growth phase.

    OBJECTIVE: The present study intends to monitor variations in deaths and identify the growth phases such as pre-growth, growth, and post-growth phases in Pakistan due to the COVID-19 pandemic.

    METHODS: New approaches are needed that display the death patterns and signal an alarming situation so that corrective actions can be taken before the condition worsens. To meet this purpose, secondary data on daily reported deaths due to the COVID-19 pandemic have been considered, and the $c$ and exponentially weighted moving average (EWMA) control charts are used To meet this purpose, secondary data on daily reported deaths in Pakistan due to the COVID-19 pandemic have been considered. The $ c$ and exponentially weighted moving average (EWMA) control charts have been used for monitoring variations.

    RESULTS: The chart shows that Pakistan switches from the pre-growth to the growth phase on 31 March 2020. The EWMA chart demonstrates that Pakistan remains in the growth phase from 31 March 2020 to 17 August 2020, with some indications signaling a decrease in deaths. It is found that Pakistan moved to a post-growth phase for a brief period from 27 July 2020 to 28 July 2020. Pakistan switches to re-growth phase with an alarm on 31/7/2020, right after the short-term post-growth phase. The number of deaths starts decreasing in August in that Pakistan may approach the post-growth phase shortly.

    CONCLUSION: This amalgamation of control charts illustrates a systematic implementation of the charts for government leaders and forefront medical teams to facilitate the rapid detection of daily reported deaths due to COVID-19. Besides government and public health officials, it is also the public's responsibility to follow the enforced standard operating procedures as a temporary remedy of this pandemic in ensuring public safety while awaiting a suitable vaccine to be discovered.

    Matched MeSH terms: Pneumonia, Viral/virology
  18. Fulltext Cancer and COVID-19 vaccines: a complex global picture
    Yusuf A, Sarfati D, Booth CM, Pramesh CS, Lombe D, Aggarwal A, et al.
    Lancet Oncol, 2021 06;22(6):749-751.
    PMID: 33930324 DOI: 10.1016/S1470-2045(21)00244-8
    Matched MeSH terms: Neoplasms/virology
  19. Fulltext SARS coronavirus outbreaks past and present-a comparative analysis of SARS-CoV-2 and its predecessors
    Low ZY, Yip AJW, Sharma A, Lal SK
    Virus Genes, 2021 Aug;57(4):307-317.
    PMID: 34061288 DOI: 10.1007/s11262-021-01846-9
    The Coronavirus Disease 2019 (COVID-19), a pneumonic disease caused by the SARS Coronavirus 2 (SARS-CoV-2), is the 7th Coronavirus to have successfully infected and caused an outbreak in humans. Genome comparisons have shown that previous isolates, the SARS-related coronavirus (SARSr-CoV), including the SARS-CoV are closely related, yet different in disease manifestation. Several explanations were suggested for the undetermined origin of SARS-CoV-2, in particular, bats, avian and Malayan pangolins as reservoir hosts, owing to the high genetic similarity. The general morphology and structure of all these viral isolates overlap with analogous disease symptoms such as fever, dry cough, fatigue, dyspnoea and headache, very similar to the current SARS-CoV-2. Chest CT scans for SARS-CoV-2, SARS-CoV and MERS-CoV reveal pulmonary lesions, bilateral ground-glass opacities, and segmental consolidation in the lungs, a common pathological trait. With greatly overlapping similarities among the previous coronavirus, the SARS-CoV, it becomes interesting to observe marked differences in disease severity of the SARS-CoV-2 thereby imparting it the ability to rapidly transmit, exhibit greater stability, bypass innate host defences, and increasingly adapt to their new host thereby resulting in the current pandemic. The most recent B.1.1.7, B.1.351 and P.1 variants of SARS-CoV-2, highlight the fact that changes in amino acids in the Spike protein can contribute to enhanced infection and transmission efficiency. This review covers a comparative analysis of previous coronavirus outbreaks and highlights the differences and similarities among different coronaviruses, including the most recent isolates that have evolved to become easily transmissible with higher replication efficiency in humans.
    Matched MeSH terms: Coronavirus Infections/virology
  20. Clinical and pathological manifestations of human henipavirus infection
    Wong KT, Tan CT
    Curr. Top. Microbiol. Immunol., 2012;359:95-104.
    PMID: 22427144 DOI: 10.1007/82_2012_205
    The clinicopathological features of human Nipah virus and Hendra virus infections appear to be similar. The clinical manifestations may be mild, but if severe, includes acute encephalitic and pulmonary syndromes with a high mortality. The pathological features in human acute henipavirus infections comprise vasculopathy (vasculitis, endothelial multinucleated syncytia, thrombosis), microinfarcts and parenchymal cell infection in the central nervous system, lung, kidney and other major organs. Viral inclusions, antigens, nucleocapsids and RNA are readily demonstrated in blood vessel wall and numerous types of parenchymal cells. Relapsing henipavirus encephalitis is a rare complication reported in less than 10% of survivors of the acute infection and appears to be distinct from the acute encephalitic syndrome. Pathological evidence suggests viral recrudescence confined to the central nervous system as the cause.
    Matched MeSH terms: Blood Vessels/virology; Central Nervous System/virology; Kidney/virology; Lung/virology; Myocardial Infarction/virology; Encephalitis, Viral/virology; Henipavirus Infections/virology
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