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Displaying publications 41 - 49 of 49 in total

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Fulltext Isolation of monoclonal antibodies-escape variant of dengue virus serotype 1

Chua SK, Selvanesan S, Sivalingam B, Chem YK, Norizah I, Zuridah H, et al.

Singapore Med J, 2006 Nov;47(11):940-6.
PMID: 17075660

During an outbreak from December 2004 to March 2005, 138 isolates of dengue virus were prospectively obtained from acute-phase serum samples of 1,067 patients with the provisional clinical diagnosis of acute dengue illness admitted to the adult wards of Hospital Tengku Ampuan Rahimah, Klang, Malaysia. Of the 138 dengue virus isolates, 87, 11, 24 and 3 were typed as dengue serotypes 1, 2, 3 and 4, respectively, by a commercial dengue virus typing kit using monoclonal antibodies (Mab). 13 dengue virus isolates could not be assigned to any specific serotype by serotyping Mab and molecular typing using dengue-type specific molecular typing primer pairs. We report the associated clinical features and limited molecular genetics of this Mab-escape dengue virus variant.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods*
Fulltext Early detection of dengue virus by use of reverse transcription-recombinase polymerase amplification

Teoh BT, Sam SS, Tan KK, Danlami MB, Shu MH, Johari J, et al.

J Clin Microbiol, 2015 Mar;53(3):830-7.
PMID: 25568438 DOI: 10.1128/JCM.02648-14

A method for the rapid diagnosis of early dengue virus (DENV) infection is highly needed. Here, a prototype reverse transcription-recombinase polymerase amplification (RT-RPA) assay was developed. The assay detected DENV RNA in <20 min without the need for thermocycling amplification. The assay enabled the detection of as few as 10 copies of DENV RNA. The designed RT-RPA primers and exo probe detected the DENV genome of at least 12 genotypes of DENV circulating globally without cross-reacting with other arboviruses. We assessed the diagnostic performance of the RT-RPA assay for the detection of DENV RNA in 203 serum samples of patients with clinically suspected dengue. The sera were simultaneously tested for DENV using a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay, quantitative RT-PCR (qRT-PCR), and IgM- and IgG-capture enzyme-linked immunosorbent assays (ELISA). Acute DENV infection was confirmed in 130 samples and 61 of the samples (46.9%) were classified as viremic with qRT-PCR. The RT-RPA assay showed good concordance (κ of ≥0.723) with the RT-LAMP and qRT-PCR assays in detecting the dengue viremic samples. When used in combination with ELISA, both the RT-RPA and RT-LAMP assays increased the detection of acute DENV infection to ≥95.7% (≥45/47) in samples obtained within 5 days of illness. The results from the study suggest that the RT-RPA assay is the most rapid molecular diagnostic tool available for the detection of DENV. Hence, it is possible to use the RT-RPA assay in a laboratory to complement routine serology testing for dengue.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods*
Development of SYBR green I based one-step real-time RT-PCR assay for the detection and differentiation of very virulent and classical strains of infectious bursal disease virus

Kong LL, Omar AR, Hair Bejo M, Ideris A, Tan SW

J Virol Methods, 2009 Nov;161(2):271-9.
PMID: 19591873 DOI: 10.1016/j.jviromet.2009.06.023

A SYBR Green I based one-step real-time reverse transcriptase polymerase chain reaction was developed for the detection and differentiation of very virulent (vv) and classical strains of infectious bursal disease virus (IBDV). The assay showed high PCR efficiency >93% and high reproducibility with coefficient of variation less than 0.5%. When tested on characterized IBDV strains, the very virulent and classical-specific primers detected accurately only vvIBDV and classical IBDV strains, respectively. The diagnostic efficacy of the assay was also tested on 140 bursal samples from experimental infection and 37 bursal samples from cases suspected of IBD. The assay was able to detect IBDV from bursal samples collected at days 3 and 5 post-infection with the vvIBDV strain UPM94/273 and the classical IBDV strain D78. The assay was also able to detect bursal samples infected dually with D78 and UPM94/273. The melting temperature values of the amplification products from the classical and very virulent viral infection were statistically significant (P<0.05). The specificity of the assay for detecting IBDV from suspected cases was confirmed by sequence analysis of the VP2 gene. The assay showed high sensitivity since bursal samples which were negative for IBDV were confirmed by virus isolation and PCR amplification. Hence, the new assay offers an attractive method for rapid detection of strains of IBDV.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods
Fulltext Epidemiologic and virologic investigation of hand, foot, and mouth disease, southern Vietnam, 2005

Van Tu P, Thao NTT, Perera D, Truong KH, Tien NTK, Thuong TC, et al.

Emerg Infect Dis, 2007 Nov;13(11):1733-41.
PMID: 18217559 DOI: 10.3201/eid1311.070632

During 2005, 764 children were brought to a large children's hospital in Ho Chi Minh City, Vietnam, with a diagnosis of hand, foot, and mouth disease. All enrolled children had specimens (vesicle fluid, stool, throat swab) collected for enterovirus isolation by cell culture. An enterovirus was isolated from 411 (53.8%) of the specimens: 173 (42.1%) isolates were identified as human enterovirus 71 (HEV71) and 214 (52.1%) as coxsackievirus A16. Of the identified HEV71 infections, 51 (29.5%) were complicated by acute neurologic disease and 3 (1.7%) were fatal. HEV71 was isolated throughout the year, with a period of higher prevalence in October-November. Phylogenetic analysis of 23 HEV71 isolates showed that during the first half of 2005, viruses belonging to 3 subgenogroups, C1, C4, and a previously undescribed subgenogroup, C5, cocirculated in southern Vietnam. In the second half of the year, viruses belonging to subgenogroup C5 predominated during a period of higher HEV71 activity.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods
Implementation in Australia of molecular diagnostic techniques for the rapid detection of foot and mouth disease virus

Boyle DB, Taylor T, Cardoso M

Aust Vet J, 2004 Jul;82(7):421-5.
PMID: 15354851

OBJECTIVE: To evaluate and implement rapid molecular diagnostic techniques for the detection of foot and mouth disease virus (FMDV) suitable for use in Australia.
DESIGN: Two PCR TaqMan assays targeted to the FMDV internal ribosome entry site or the 3D polymerase coding region for the rapid detection of FMDV were evaluated using non-infectious materials to determine the test most appropriate for implementation as part of Australia's national preparedness for the rapid detection and diagnosis of FMD outbreaks.
RESULTS: Two published tests (PCR TaqMan assays targeted to the FMDV IRES region or the FMDV 3D polymerase coding region) were evaluated for their ability to detect FMDV genetic material in non-infectious FMDV ELISA antigen stocks held at Australian Animal Health Laboratory. Both tests were able to detect FMDV genetic material from strains O1 Manisa, O-3039, A22, A24, A Malaysia, C, Asia 1 and SAT 1, 2 and 3. With the exception of Asia 1, the TaqMan assay targeted to the FMD 3D polymerase coding region had Ct values equal to or lower than for the TaqMan assay targeted to the IRES region suggesting that this test may provide broader serotype detection and sensitivity. However, the TaqMan assay directed to the FMDV IRES is the only one to date to have undergone substantial evaluation using clinical samples collected during an outbreak. The greatest differences observed were for O-3039, SAT 1, and 3.
CONCLUSION: Given the ease of setting up both tests, AAHL currently runs both tests on highly suspect FMD investigations to provide independent confirmation of the absence of FMDV because the tests are focused on two independent regions of the FMDV genome. These tests add substantially to Australia's preparedness for FMD diagnosis complementing the already well-established virus isolation and antigen capture ELISA tests for index case diagnosis of FMD in Australia.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods
Fulltext Development of conventional and real-time reverse transcription polymerase chain reaction assays to detect Tembusu virus in Culex tarsalis mosquitoes

Petz LN, Turell MJ, Padilla S, Long LS, Reinbold-Wasson DD, Smith DR, et al.

Am J Trop Med Hyg, 2014 Oct;91(4):666-71.
PMID: 25114013 DOI: 10.4269/ajtmh.13-0218

Tembusu virus (TMUV) is an important emerging arthropod-borne virus that may cause encephalitis in humans and has been isolated in regions of southeast Asia, including Malaysia, Thailand, and China. Currently, detection and identification of TMUV are limited to research laboratories, because quantitative rapid diagnostic assays for the virus do not exist. We describe the development of sensitive and specific conventional and real-time quantitative reverse transcription polymerase chain reaction assays for detecting TMUV RNA in infected cell culture supernatant and Culex tarsalis mosquitoes. We used this assay to document the replication of TMUV in Cx. tarsalis, where titers increased 1,000-fold 5 days after inoculation. These assays resulted in the detection of virus-specific RNA in the presence of copurified mosquito nucleic acids. The use of these rapid diagnostic assays may have future applications for field pathogen surveillance and may assist in early detection, diagnosis, and control of the associated arthropod-borne pathogens.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods*
A preliminary study of dengue infection in Brunei

Osman O, Fong MY, Devi S

Jpn J Infect Dis, 2007 Jul;60(4):205-8.
PMID: 17642533

The purpose of this study was to examine the extent of dengue infection in Brunei and to determine the predominant serotype circulating in the country. The study generated useful epidemiological data on dengue infection in Brunei. A total of 271 samples from patients suspected of having dengue infections were selected and analyzed. All patients were seen in clinics and hospitals in Brunei. The samples were collected from April 2005 to April 2006 and transported to the WHO Collaborating Centre for Arbovirus Reference and Research, University of Malaya, Malaysia. The following tests were used to achieve the objectives: in-house IgM-capture enzyme-linked immunosorbent assay, virus isolation in mosquito albopictus cell line (C6/36), and viral RNA detection and serotyping by reverse transcriptase-polymerase chain reaction (RT-PCR). The results show that 45 people were positive for dengue-specific IgM (27 males and 18 females), while RT-PCR detected dengue viral RNA in 12 patients, 3 identified as DEN-1 and 9 as DEN-2. Dengue virus was isolated from 6 patients using the C6/36 cell line; 3 were DEN-2 isolates and 3 were DEN-1 isolates. These data show that dengue virus is circulating in Brunei and the predominant infecting serotype for that period was DEN-2 followed by DEN-1. This study is the first to report the detection and isolation of dengue virus from Brunei using RT-PCR and culture in the C6/36 albopictus mosquito cell line.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods
Rapid detection of prognostically important childhood acute lymphoblastic leukemia chimeric transcripts using multiplex SYBR green real-time reverse transcription PCR

Ibrahim K, Daud SS, Seah YL, Yeoh AE, Ariffin H, Malaysia-Singapore Leukemia Study Group

Ann Clin Lab Sci, 2008;38(4):338-43.
PMID: 18988926

Childhood acute lymphoblastic leukaemia (ALL) is a heterogenous disease in which oncogene fusion transcripts are known to influence the biological behaviour of the different ALL subtypes. Screening for prognostically important transcripts is an important diagnostic step in treatment stratification and prognostication of affected patients. We describe a SYBR-Green real-time multiplex PCR assay to screen for transcripts TEL-AML1, E2A-PBX1, MLL-AF4, and the two breakpoints of BCR-ABL (p190 and p210). Validation of the assay was based on conventional karyotyping results. This new assay provides a rapid, sensitive, and accurate detection method for prognostically important transcripts in childhood ALL.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods*
Clinical implications of conventional cytogenetics, fluorescence in situ hybridization (FISH) and molecular testing in chronic myeloid leukaemia patients in the tyrosine kinase inhibitor era - A review

Ankathil R, Ismail SM, Mohd Yunus N, Sulong S, Husin A, Abdullah AD, et al.

Malays J Pathol, 2020 Dec;42(3):307-321.
PMID: 33361712

Chronic myeloid leukaemia (CML) provides an illustrative disease model for both molecular pathogenesis of cancer and rational drug therapy. Imatinib mesylate (IM), a BCR-ABL1 targeted tyrosine kinase inhibitor (TKI) drug, is the first line gold standard drug for CML treatment. Conventional cytogenetic analysis (CCA) can identify the standard and variant Philadelphia (Ph) chromosome, and any additional complex chromosome abnormalities at diagnosis as well as during treatment course. Fluorescence in situ hybridization (FISH) is especially important for cells of CML patients with inadequate or inferior quality metaphases or those with variant Ph translocations. CCA in conjunction with FISH can serve as powerful tools in all phases of CML including the diagnosis, prognosis, risk stratification and monitoring of cytogenetic responses to treatment. Molecular techniques such as reverse transcriptase-polymerase chain reaction (RT-PCR) is used for the detection of BCR-ABL1 transcripts at diagnosis whereas quantitative reverse transcriptase-polymerase chain reaction (qRTPCR) is used at the time of diagnosis as well as during TKI therapy for the quantitation of BCR-ABL1 transcripts to evaluate the molecular response and minimal residual disease (MRD). Despite the excellent treatment results obtained after the introduction of TKI drugs, especially Imatinib mesylate (IM), resistance to TKIs develops in approximately 35% - 40% of CML patients on TKI therapy. Since point mutations in BCR-ABL1 are a common cause of IM resistance, mutation analysis is important in IM resistant patients. Mutations are reliably detected by nested PCR amplification of the translocated ABL1 kinase domain followed by direct sequencing of the entire amplified kinase domain. The objective of this review is to highlight the importance of regular and timely CCA, FISH analysis and molecular testing in the diagnosis, prognosis, assessment of therapeutic efficacy, evaluation of MRD and in the detection of BCR-ABL1 kinase mutations which cause therapeutic resistance in adult CML patients.

Matched MeSH terms: Reverse Transcriptase Polymerase Chain Reaction/methods*