Chan, Ka Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 133-150). / Abstract also in Chinese. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.iv / CONTRIBUTORS --- p.vi / TABLE OF CONTENTS --- p.vii / LIST OF TABLES --- p.x / LIST OF FIGURES --- p.xi / LIST OF ABBREVIATIONS --- p.xiii / Chapter SECTION I: --- BACKGROUND --- p.1 / Chapter CHAPTER 1: --- PRENATAL DIAGNOSIS OF FETAL TRISOMY 21 --- p.2 / Chapter 1.1 --- Down syndrome --- p.2 / Chapter 1.2 --- Current methods of prenatal diagnosis of fetal trisomy 21 --- p.3 / Chapter 1.2.1 --- Non-invasive procedures --- p.3 / Chapter 1.2.2 --- Invasive procedures --- p.5 / Chapter 1.3 --- Alternative methods for the prenatal diagnosis of fetal trisomy 21 --- p.7 / Chapter CHAPTER 2: --- CELL-FREE FETAL NUCLEIC ACIDS IN MATERNAL PLASMA --- p.13 / Chapter 2.1 --- Circulating fetal cells --- p.15 / Chapter 2.2 --- Circulating cell-free fetal nucleic acids --- p.15 / Chapter 2.3 --- Diagnostic applications of cell-free fetal nucleic acids in maternal plasma --- p.17 / Chapter 2.4 --- Digital relative chromosome dosage approach --- p.20 / Chapter 2.5 --- Validation of digital RCD approach on artificial DNA mixtures --- p.22 / Chapter SECTION II --- : MATERIALS AND METHODS --- p.25 / Chapter CHAPTER 3: --- QUANTITATIVE ANALYSIS OF NUCLEIC ACIDS --- p.26 / Chapter 3.1 --- Subject recruitment and sample collection --- p.26 / Chapter 3.2 --- Sample processing --- p.26 / Chapter 3.3 --- Nucleic acid extraction --- p.27 / Chapter 3.3.1 --- Extraction of DNA from placental tissues --- p.27 / Chapter 3.3.2 --- Extraction of DNA from maternal blood cells --- p.27 / Chapter 3.4 --- Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) --- p.28 / Chapter 3.5 --- Paralogous sequence assays optimisation workflow --- p.31 / Chapter 3.5.1 --- Monoplex paralogous sequence assays --- p.31 / Chapter 3.5.2 --- Multiplex paralogous sequence assay --- p.38 / Chapter 3.6 --- Digital PCR --- p.42 / Chapter 3.6.1 --- Principle --- p.42 / Chapter 3.6.2 --- Digital multiplex paralogous sequence assay --- p.42 / Chapter 3.7 --- Statistical analysis --- p.46 / Chapter 3.7.1 --- Disease classification of samples --- p.46 / Chapter 3.7.2 --- Poisson distribution --- p.46 / Chapter 3.7.3 --- Data analysis --- p.48 / Chapter 3.7.4 --- Sequential probability ratio test (SPRT) analysis --- p.49 / Chapter SECTION III: --- ASSAY DEVELOPMENT --- p.53 / Chapter CHAPTER 4: --- TESTING OF ASSAY SPECIFICITY WITH CORIELL CELL LINES --- p.54 / Chapter 4.1 --- Coriell cell lines --- p.54 / Chapter 4.2 --- Specificity of initial PCR primers --- p.56 / Chapter 4.2.1 --- Principle --- p.56 / Chapter 4.2.2 --- Materials and methods --- p.56 / Chapter 4.2.3 --- Results --- p.60 / Chapter 4.2.4 --- Conclusion --- p.63 / Chapter 4.3 --- Specificity of the iPLEX® Gold extension primers --- p.63 / Chapter 4.3.1 --- Principle --- p.63 / Chapter 4.3.2 --- Materials and methods --- p.64 / Chapter 4.3.3 --- Results --- p.65 / Chapter 4.4 --- Further analysis on the specificity of PV2107a initial PCR primers --- p.67 / Chapter 4.5 --- Conclusion --- p.71 / Chapter CHAPTER 5: --- ASSAY OPTIMISATION --- p.72 / Chapter 5.1 --- Introduction --- p.72 / Chapter 5.2 --- Optimisation of initial PCRs with AmpliTaq Gold® DNA polymerase followed by homogeneous MassEXTEN´DёØ (hME) assays (Sequenom) --- p.72 / Chapter 5.2.1 --- Optimisation of initial PCR reactions --- p.72 / Chapter 5.2.2 --- Principle of homogeneous MassEXTEN´DёØ assays (Sequenom)… --- p.75 / Chapter 5.2.3 --- Homogeneous MassEXTEN´DёØ assays (Sequenom) on euploid and T21 samples --- p.76 / Chapter 5.3 --- Assay selection by iPLEX® Gold single base primer extension reactions (Sequenom) --- p.82 / Chapter 5.4 --- Optimisation of multiplex PCR with AmpliTaq Gold® DNA polymerase --- p.88 / Chapter 5.5 --- Optimisation of multiplex iPLEX® Gold single base primer extension reaction --- p.93 / Chapter 5.6 --- Single molecule detection test for the multiplex paralogous sequence assays … --- p.103 / Chapter SECTION IV: --- ANALYSIS OF CLINICAL SAMPLES --- p.107 / Chapter CHAPTER 6: --- DISEASE CLASSIFICATION OF EUPLOID AND TRISOMY SAMPLES WITH MULTIPLEX PARALOGOUS SEQUENCE ASSAY --- p.108 / Chapter 6.1 --- Introduction --- p.108 / Chapter 6.2 --- Materials and methods --- p.109 / Chapter 6.2.1 --- Sample collection --- p.109 / Chapter 6.2.2 --- Experimental design --- p.110 / Chapter 6.3 --- Results --- p.111 / Chapter 6.4 --- Discussion --- p.114 / Chapter SECTION V: --- CONCLUDING REMARKS --- p.122 / Chapter CHAPTER 7: --- CONCLUSION AND FUTURE PERSPECTIVES --- p.123 / Chapter 7.1 --- Conclusion --- p.123 / Chapter 7.2 --- Future perspectives --- p.124 / Appendix 1 --- p.126 / Appendix II --- p.127 / REFERENCE --- p.133

Tse, Ka Yan Agnes. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 106-113). / Abstract also in Chinese. / Table of Contents --- p.i / List of Figures and Tables --- p.iii / List of Abbreviations --- p.vi / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Breast cancer overview --- p.1 / Chapter 1.2 --- General mechanism of breast carcinoma --- p.5 / Chapter 1.3 --- Ductal carcinoma in situ (DCIS) --- p.7 / Chapter 1.3.1 --- Clinical features of DCIS --- p.7 / Chapter 1.3.2 --- Classification of DCIS --- p.8 / Chapter 1.3.3 --- Molecular markers for DCIS --- p.14 / Chapter 1.3.4 --- Progression of DCIS --- p.19 / Chapter 1.4 --- Aim of project --- p.20 / Chapter Chapter 2: --- Materials and Methods --- p.21 / Chapter 2.1 --- Categorization of DCIS samples using Van Nuys Grading System --- p.21 / Chapter 2.2 --- "RNA extraction and reverse transcription of formalin-fixed, paraffin embedded (FFPE) DCIS samples" --- p.22 / Chapter 2.2.1 --- "Formalin-fixed, paraffin embedded (FFPE) DCIS sample" --- p.22 / Chapter 2.2.2 --- Tissue Microarray (TMA) --- p.24 / Chapter 2.2.3 --- RNA extraction --- p.25 / Chapter 2.2.4 --- First strand cDNA synthesis --- p.30 / Chapter 2.3 --- PCR screening for potential DCIS markers --- p.31 / Chapter 2.4 --- Statistical analysis of PCR expression pattern --- p.36 / Chapter 2.4.1 --- Chi-square lest --- p.36 / Chapter 2.4.2 --- Logistic regression --- p.37 / Chapter 2.5 --- Real-time RT-PCR analysis of the expression pattern of the potential DCIS marker --- p.39 / Chapter 2.5.1 --- Real-time RT-PCR for FFPE samples --- p.39 / Chapter 2.5.2 --- Real-time RT-PCR in the study --- p.40 / Chapter 2.6 --- Statistical analysis of real-time RT-PCR results --- p.41 / Chapter 2.7 --- Immunohistological analysis of the expression pattern of the potential DCIS marker --- p.42 / Chapter 2.8 --- Evaluation of immunohistological staining --- p.44 / Chapter 2.9 --- Statistical analysis of immunohistological results --- p.44 / Chapter Chapter 3: --- Analysis of expression pattern of potential DCIS markers --- p.45 / Chapter 3.1 --- Construction of DCIS data base from FFPE samples --- p.45 / Chapter 3.2 --- Analysis of expression of potential DCIS marker from PCR --- p.46 / Chapter 3.2.1 --- First strand cDNA synthesis and PCR screening --- p.46 / Chapter 3.2.2 --- Statistical analysis of PCR results --- p.60 / Chapter 3.3 --- Conclusion --- p.66 / Chapter Chapter 4: --- Real-time RT-PCR analysis of expression of selected potential DCIS markers --- p.67 / Chapter 4.1 --- Expression of ETV6 in tumor and adjacent normal tissues in different DCIS grades --- p.69 / Chapter 4.2 --- Expression of Erbb2 in tumor and adjacent normal tissues in different DCIS grades --- p.71 / Chapter Chapter 5: --- Analysis of Protein Expression Pattern of Potential DCIS Markers --- p.73 / Chapter 5.1 --- Chi square test --- p.73 / Chapter 5.1.1 --- Immunohistochemical study of ETV6 in tumor and adjacent normal DCIS --- p.74 / Chapter 5.1.2 --- Immunohistochemical study of Erbb2 in tumor and adjacent normal DCIS tissues --- p.77 / Chapter 5.2 --- Conclusion --- p.80 / Chapter Chapter 6: --- General discussion --- p.81 / References --- p.106

Magister Scientiae (Biodiversity and Conservation Biology) / Land-based abalone aquaculture in South Africa started in the early 1990s and is based on the local species Haliotis midae. This industry expanded with great success over the last decade. In 2006 abalone exhibiting typical clinical signs of tubercle mycosis was discovered for the first time in South African abalone culture facilities,posing a significant threat to the industry. Halioticida noduliformans, a fungus belonging to the Peronosporomycetes (formerly Oomycetes), has been identified as the causative agent of abalone tubercle mycosis (ATM). While diagnoses of this disease are currently done by gross observation and histopathology, these methods fail to be sensitive enough to identify the causative agent accurately and reliably.Molecular confirmation could provide for quicker more accurate diagnostic information. The aim of this study was to develop a DNA based molecular diagnostic test. Polymerase chain reaction (PCR) has been used to rapidly detect, characterise and identify a variety of organisms. Nucleotide sequences of the smalland large-subunit ribosomal ribonucleic acid (rRNA) and mitochondrial cytochrome oxidase subunit II (cox2) genes of H. noduliformans were compared with closely related Peronosporomycete gene sequences to identify potential PCR primer sites. H. noduliformans specific real-time quantitative PCR (Q-PCR) primer sets were designed and optimised for each of the selected genes. Results indicate that, although all tested primers sets could amplify fungal DNA, only the LSU and cox2 primer sets - v -demonstrated no cross-amplification with the closely related Peronosporomycete and non-fungal DNA tested in the present study. The H. noduliformans specific LSU primer set was chosen for further analysis and used for all subsequent real-time PCR assays. The lowest detection limit for the LSU primer set was evaluated by running Q-PCR on serial dilutions of known quantities of extracted H. noduliformans DNA.Serial dilutions were made in PCR grade water as well as in an abalone tissue matrix.The sensitivity of the Q-PCR reaction was determined to be 266 pg of H.noduliformans DNA per 25 μL reaction volume. However, inclusion of a nested PCR step, utilising universal fungal outer primers, followed by Q-PCR with the H.noduliformans LSU specific primers improved sensitivity to 0.266 pg of H.noduliformans DNA per 25 μL reaction volume. This equates to approximately 2.4spores per 25 μL reaction volume. DNA extraction protocols were optimised to ensure efficient and repeatable extraction of high quality fungal DNA from pure fungus and tissue samples spiked with known quantities of fungal DNA. PCR amplification efficiency and potential inhibition were examined for each extraction method. Results suggest that real-time PCR has great potential in monitoring and quantifying H. noduliformans on abalone culture facilities in South Africa.

Title from PDF of title page. / Document formatted into pages; contains 57 pages. / Thesis (M.S.P.H.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The Centers for Disease Control and Prevention estimated 23,000,000 cases of viral gastroenteritis caused by Norovirus in 2000, 40% of which were transmitted by food including: a variety of fresh produce, cake, deli meats, fruit salad, cheeses and ice. (CDC, 2003). An estimated 83,391 cases of Hepatitis A virus was reported in 2000, of which 5% was attributed to foodborne transmission (CDC, 2003). These figures underscore an urgent need for a method that can isolate virus from a variety of food matrices. The aim of this study was to develop an overall assessment of the inhibitory effects of a variety of food matrices on Real Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). / ABSTRACT: Additionally, to compare a sequence specific hybridization probe amplification format to a non sequence specific SYBR Green format using the Roche LightCycler. The secondary aim was to evaluate the effectiveness of a food virus concentration and isolation protocol under development at the Florida Department of Health Bureau of Laboratories, Tampa. Three food specimens consisting of prepackaged smoked ham, fresh cilantro, and Thompson's green grapes were seeded with three dilutions of poliovirus 3 (Sabin strain). A viral concentration procedure under development at the Florida Department of Health Bureau of Laboratories, Tampa was used to isolate the virus. Real Time RT-PCR was carried out on the Roche LightCycler in SYBR Green and Hybridization probe formats. Spiking the virus-negative samples of each matrix with a dilution series of poliovirus 3 created post flocculation spikes. / ABSTRACT: This post-flocculation dilution series amplification allowed a standard curve to be created unique to each food matrix. The flocculation and concentrations specimens were then amplified and the standard curves from the post-flocculation seed were used to calculate the loss associated with the concentration procedure. This study reports significant differences (p[0.05) in recovery detected between the various matrices, and Real Time RT-PCR formats. The concentration protocol under development at the Florida Department of Health Bureau of Laboratories, Tampa, demonstrates a 12-78% recovery of seeded virus in a simulated "real world" virus contamination event among the various matrices. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

The objective of this study was to develop and validate a six Non-CODIS miniSTR genotyping system and to determine its suitability for forensic casework in South Africa.In Non-CODIS miniSTR genotyping systems, smaller PCR products are amplified and the primers are positioned as close as possible to the repeat region. For this reason, these systems can be valuable in a variety of scenarios including complex paternity cases,missing persons work, and mass fatality disasters. After the successful implementation of the genotyping system in the laboratory, allele size range was determined for each of the loci and allelic ladders were constructed. The entire repeat regions of the six loci under investigation were successfully sequenced.Consequently, allele repeat number, structure and observed size were determined for each locus.An internal validation study of the six Non-CODIS miniSTR genotyping system was conducted following the SWGDAM guidelines. A comprehensive population study,covering five population groups from South Africa was also carried out.The genotyping system produced consistent, accurate and precise genetic profiles for low concentrations of template DNA. When analyzing mixed DNA samples, successful differentiation of minor and major DNA components was identifiable. Amplification products were observed in non-human DNA studies but in all instances complete genotype profiles were not obtained. Allele frequencies and forensic parameters were determined for the system in five South African population groups (i.e. Afrikaner, Asian-Indian, Mixed Ancestry, Xhosa and Cape Muslim). No deviation from Hardy-Weinberg equilibrium was observed in any of the populations. Furthermore, all populations displayed a high power of discrimination and a high power of exclusion.The six Non-CODIS miniSTR genotyping system has shown a good potential to aid in the analysis of degraded DNA samples. This system can be further improved by including additional loci. Even in its current form, it can certainly provide additional discrimination in complex paternity and/or missing person cases. / >Magister Scientiae - MSc

Colorectal cancer (CRC) is a common malignancy which develops due to old age and lifestyle factors, low percent of patients afflicted by a genetic disorders. Half of all colorectal cancer patients are diagnosed after metastasis. The high rate of the late detection, emphasizes on the requirement of convenient and inexpensive diagnostic methods for comprehensive screening programs. The aim of this study was to discover proto-oncogenes mutation and assessment of tumor suppressor genes expression. Formalin fixed paraffin embedded (FFPE) histologically verified colorectal cancer samples were used. APC, KRAS and BRAF mutations were investigated using polymerase chain reaction (PCR) fragments and direct sequencing. Gene expression assessment of MLH1, MGMT and CDKN2A were achieved via quantitative polymerase chain reaction (qPCR). In the present study we could detect a novel transversion heterozygous mutation in APC gene codon 1365 in three patients. BRAF codon 600 mutation were detected in one patient. KRAS codon 12 mutation was discovered in one sample and also a novel transition mutation in codon 15 was detected in 6 patients. In 80% of cases, MLH1 and MGMT expression were undetectable, in remaining 20%, MLH1 expression were reduced, but MGMT showed both reduced and increased expression compared to control. In 100% of patients CDKN2A expression was undetectable. The rate of mutations in predetermined hotspot codons and amount of uncommon mutations into APC, BRAF and KRAS in Nepalese patients indicates the requirement of further investigation in CRC patients from that part of the world. Also, the expression rate of MLH1, MGMT, CDKN2A and deficiency of an information source emphasizes the necessity of whole genome CRC expression profiling data to comparison and conclusion. / <p>-</p> / -

Made available in DSpace on 2015-07-22T20:50:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-28. Added 1 bitstream(s) on 2015-08-11T03:26:00Z : No. of bitstreams: 1 Publico-119.pdf: 1451822 bytes, checksum: feaf2803cde522b94132a62f8fde6def (MD5) / Introdução: A identificação de 42 formas recombinantes circulantes (CRF) de HIV-1, juntamente com suas inúmeras formas recombinantes únicas, evidencia ainda mais o papel da recombinação gênica para esta epidemia. No Brasil, os subtipos B, F e C co-circulam, sendo que cinco CRF entre eles foram recém descobertas. A PCR em tempo real é uma ferramenta rápida, confiável e capaz de detectar diferentes subtipos de HIV-1 e suas formas recombinantes. Objetivo: O objetivo deste trabalho foi desenvolver sistemas de PCR em tempo real capazes de detectar vírus dos subtipos B e F, bem como recombinantes B/F gerados por ensaios de competição in vitro, e, assim, obter uma ferramenta para triagem das CRF brasileiras, 28 e 29, também recombinantes B/F. No futuro, estes sistemas serão testados para discriminação de subtipos de amostras clínicas. Metodologia: Células MT-4 foram infectadas separadamente pelos isolados virais BZ167 (subtipo B) e BR020 (subtipo F), e o sobrenadante foi coletado para otimização dos sistemas de PCR em tempo real (TaqMan®) desenvolvidos para detectar o subtipo de diferentes regiões genômicas, incluindo o gene pol (protease, transcriptase reversa, integrase) e o gene env (gp120 e gp41). Os primers desenhados deveriam amplificar igualmente o subtipo B e F; por outro lado, foram necessárias sondas subtipo-específicas capazes de detectar o subtipo presente no sobrenadante da cultura. As células MT-4 também foram co-infectadas por ambos os isolados, B e F, em iguais condições, para averiguação da possível geração de recombinantes. Para futura validação do uso destes sistemas em amostras clínicas, 157 amostras provenientes do Município de Santos, submetidas à genotipagem, foram seqüenciadas e subtipadas para as cinco regiões genômicas estudadas, utilizando o pacote Philip 3.5, sendo Neighbor-Joining o algoritmo de escolha. Resultados: Os sistemas desenvolvidos apresentaram-se capazes de detectar especificamente os isolados virais. A eficiência estimada para cada sistema, sendo um cálculo para a sonda do subtipo B e outro para F foram de, respectivamente: 80,97 e 85,16% para a região da protease; 89,80 e 75,09% para a região da transcriptase reversa; 80,90 e 83,83% para a região da integrase; 93,49 e 98,93% para a região da gp120; e 88,45 e 80,19% para a região da gp41. Nos ensaios de co-cultivo, a detecção de cada subtipo na primeira e na quinta passagem aconteceu de forma diferente, com variações na média dos valores de Cycle threshold (Ct) de intensidades diferentes. De uma forma geral, a concentração inicial do subtipo B pareceu diminuir, chegando a ficar indetectável em algumas regiões, enquanto do subtipo F pareceu aumentar ao longo das passagens para todas as regiões amplificadas (protease, transcriptase reversa, gp120 e gp41). A exceção foi a região da integrase, para qual foi detectado sinal somente para o subtipo B, sendo este sinal crescente ao longo do tempo. Do seqüenciamento e subtipagem das 157 amostras provenientes da cidade de Santos, foram obtidas seqüências de todas as regiões estudadas para 71 amostras. Destas, 43 foram subtipadas como B em todas as regiões, e somente três como F. De acordo com o padrão de distribuição de subtipos para as regiões, foram encontradas 12 seqüências com o padrão da CRF_28 e 9 no padrão da CRF_29. Nenhum subtipo C foi encontrado em nenhuma das regiões em estudo. Conclusão: O uso da técnica de PCR em tempo real para identificação de subtipos de fragmentos em cultura celular e para avaliação da dinâmica replicativa da recombinação em culturas co-infectadas reforça seu potencial uso em futuros testes in vivo para identificação de estruturas recombinantes. Esta metodologia mostrou ser eficiente, de mais fácil manipulação e mais econômica que o seqüenciamento de DNA. Os ensaios de co-cultivo amplificados pelos sistemas desenvolvidos sugeriram uma distribuição divergente nos subtipos resultantes para as diferentes regiões, sendo um grande indicativo de recombinação. O seqüenciamento das amostras clínicas evidenciou a importância das CRF em estudo, devido sua notável presença na amostragem utilizada, sendo um reflexo da epidemia de um local de grande circulação de mais de um subtipo. / Background: The discovery of 42 HIV-1 circulating recombinant forms (CRF) together with the innumerous unique HIV recombinants forms, makes clear the role of genetic recombination for the epidemic. In Brazil, clades B, F, and C co-circulate, with 5 recently described CRFs. Real Time PCR is a rapid and reliable tool capable of detecting different HIV-1 subtypes and recombinant profiles. Objective: The aim of this study was to develop real time PCR systems in order to detect the Brazilian CRF_28 and CRF_29, which are B/F recombinants, as well as detect B/F recombinants generated by in vitro competition assays. In future, these systems should be able to discriminate subtypes in clinical surveys. Methodology: MT-4 cells were separately infected with the viral strains BZ167 (subtype B) and BR020 (subtype F), and supernatant was collected in order to optimizing the real time PCR systems (TaqMan®) developed to detect the subtype profile of different genomic regions, including pol gene (protease, reverse transcriptase, integrase) and env gene (gp120 and gp41). The designed primers should be able to equally amplify the subtype B and F, which should be discriminated by subtype-specific probes. For future validation of these PCR systems, 157 clinical samples from the city of Santos were sequenced and phylogeneticaly analyzed in order to perform the clade assignment with Neighbor-Joining algorithm (Phylip software package v3.5). Results: The designed systems were able to differentiate the utilized viral strains. The estimated efficiencies for each system, for each probe, subtypes B and F separately, were respectively: 80,97 and 85,16% for protease region; 89,80 and 75,09% for reverse transcriptase region; 80,90% and 83,83% for integrase region; 93,49 and 98,93% for gp120 region; and 88,45 and 80,19% for gp41 region. For the co-infected cell culture, the detection of each subtype was performed in the first and fifth passages. Generally, the initial concentration of subtype B appeared to have decreased, some of them becoming undetectable, whereas subtype F seemed to increase with the passages, for protease, reverse transcriptase, gp120 and gp41 regions. The integrase region was an exception, since only the subtype B was detected, with increasing Cycle threshold (Ct) values over time. Sequencing results revealed that 65 out of 157 samples had the subtype profile defined for all regions. 43 out of 71 were defined as B, whereas 3 were F in all regions. 12 samples presented the CRF_28 profile, and 9 samples presented the CRF_29 profile. There were no subtype C samples in any genomic regions analyzed. Conclusion: The use of real time PCR technique for identification of fragments’ subtypes in cell culture and for evaluation of replicative dynamics of recombination in co-infected cultures warrants its potential use in future in vivo surveys. This methodology proved to be efficient, fast, less cumbersome and less expensive than DNA sequencing. The newly designed systems performed for supernatant of competition assays had suggested a divergent distribution of subtypes for the different regions, which reflects the possibility of genetic recombination. Results from clinical samples revealed a high prevalence of CRF_28/29 in this geographic region, thus reflecting the resulting consequence of different co-circulating strains and pointing to the need for a careful surveillance. / TEDE / BV UNIFESP: Teses e dissertações

Made available in DSpace on 2014-06-11T19:27:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-12Bitstream added on 2014-06-13T20:35:37Z : No. of bitstreams: 1 lopes_mc_me_araca.pdf: 187442 bytes, checksum: e5c382aecfe4bb38f157a656bfad5f2a (MD5) / As análises antigênica e genética são ferramentas importantes para o estudo da epidemiologia da raiva em uma região. A recuperação e reisolamento viral a partir de amostras conservadas por longos períodos em temperatura de congelamento é essencial para estudos retrospectivos. Porém, o tempo de conservação, associado a repetidos ciclos de congelamento e descongelamento, promove uma perda significativa na viabilidade do vírus, condição esta que pode ser contornada com a utilização de técnicas de biologia molecular, como a RT-PCR. Com o objetivo de verificar a viabilidade e detectar o RNA do vírus rábico, 95 amostras com diagnóstico positivo e armazenadas por 4 a 13 anos a –20 e –80ºC foram avaliadas por inoculação intracerebral em camundongos e RT-PCR. Apenas 33,6% (32/95) das amostras inoculadas em camundongos foram positivas, enquanto que a RTPCR detectou o genoma viral em 65,3% (62/95). Houve diferença estatisticamente significativa (p<0,0001) na viabilidade das amostras e na detecção do genoma viral na amostras armazenadas por mais de 10 anos, sendo a porcentagem de positividade de 22,1% e 59,7%, respectivamente. O presente estudo confirma a importância da RT-PCR na detecção do genoma viral em amostras conservadas por longo período de tempo, incluindo aquelas em estado visível de decomposição. / The antigenic and genetic analyses are important tools for retrospective study of rabies epidemiology in a region. The recovery and viral re-isolation from samples conserved for long periods in freezing temperature are essential for these studies. However, time conservation, associated with temperature variations, causes a significative virus viability loss. On the other hand, molecular tools, such as RT-PCR, can overcome this condition. For this purpose, 95 positive samples stored for 4 to 13 years at -20 and -80ºC were evaluated by intracerebral inoculation in mice and RT-PCR. Of this total, only 33,6% (32/95) had been positive in the intracerebral inoculation, while RT-PCR detected the viral genoma in 65.3% (62/95). It had a significant difference (p>0,0001) in the viability of the samples and the detention of the viral genoma from those samples store for more than 10 years and the percentage of positivity reached 22,1% and 59,7%, respectively. The present study confirms the importance of the RT-PCR technique for detection of viral genoma in old samples, including those in apparent state of decomposition.

Orientador: Luzia Helena Queiroz da Silva / Banca: Avelino Albas / Banca: Silvana Regina Favaretto Lazarini / Resumo: As análises antigênica e genética são ferramentas importantes para o estudo da epidemiologia da raiva em uma região. A recuperação e reisolamento viral a partir de amostras conservadas por longos períodos em temperatura de congelamento é essencial para estudos retrospectivos. Porém, o tempo de conservação, associado a repetidos ciclos de congelamento e descongelamento, promove uma perda significativa na viabilidade do vírus, condição esta que pode ser contornada com a utilização de técnicas de biologia molecular, como a RT-PCR. Com o objetivo de verificar a viabilidade e detectar o RNA do vírus rábico, 95 amostras com diagnóstico positivo e armazenadas por 4 a 13 anos a -20 e -80ºC foram avaliadas por inoculação intracerebral em camundongos e RT-PCR. Apenas 33,6% (32/95) das amostras inoculadas em camundongos foram positivas, enquanto que a RTPCR detectou o genoma viral em 65,3% (62/95). Houve diferença estatisticamente significativa (p<0,0001) na viabilidade das amostras e na detecção do genoma viral na amostras armazenadas por mais de 10 anos, sendo a porcentagem de positividade de 22,1% e 59,7%, respectivamente. O presente estudo confirma a importância da RT-PCR na detecção do genoma viral em amostras conservadas por longo período de tempo, incluindo aquelas em estado visível de decomposição. / Abstract: The antigenic and genetic analyses are important tools for retrospective study of rabies epidemiology in a region. The recovery and viral re-isolation from samples conserved for long periods in freezing temperature are essential for these studies. However, time conservation, associated with temperature variations, causes a significative virus viability loss. On the other hand, molecular tools, such as RT-PCR, can overcome this condition. For this purpose, 95 positive samples stored for 4 to 13 years at -20 and -80ºC were evaluated by intracerebral inoculation in mice and RT-PCR. Of this total, only 33,6% (32/95) had been positive in the intracerebral inoculation, while RT-PCR detected the viral genoma in 65.3% (62/95). It had a significant difference (p>0,0001) in the viability of the samples and the detention of the viral genoma from those samples store for more than 10 years and the percentage of positivity reached 22,1% and 59,7%, respectively. The present study confirms the importance of the RT-PCR technique for detection of viral genoma in old samples, including those in apparent state of decomposition. / Mestre

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 vi, 92 leaves / Interest in xylanases from different microbial sources has increased markedly in the past decade, in part because of the application of these enzymes in a number of industries, the main area being the pulp and paper industry. While conventional methods will continue to be applied to enzyme production from micro-organisms, the application of recombinant DNA techniques is beginning to reveal important information on the molecular basis and this knowledge is now being applied both in the laboratory and commercially. In this study, a directed evolution strategy was used to select an enzyme variant with high thermostability. This study describes the use of error-prone PCR to modify the xylanase gene from Thermomyces lanuginosus DSM 5826, rendering it tolerant to temperatures in excess of 80°C. Mutagenesis comprised of different concentrations of nucleotides and manganese ions. The variants were generated in iterative steps and subsequent screening for the best mutant was evaluated using RBB-xylan agar plates. The optimum temperature for the activity of xylanases amongst all the enzyme variants was 72°C whilst the temperature optimum for the wild type enzyme was 70°C. Long term thermostability screening was therefore carried out at 80°C and 90°C. The screen yielded a variant which had a 38% improvement in thermostability compared to the wild type xylanase from pX3 (the unmutated gene). Successive rounds of error-prone PCR were carried out and in each round the progeny mutant displayed better thermostability than the parent. The most stable variant exhibited 71% residual activity after 90 minutes at 80˚C. Sequence analysis revealed four single amino acid residue changes that possibly enhanced their thermostabilities. This in vitro enzyme evolution technique therefore served as an effective tool in improving the thermostable property of this xylanase which is an important requirement in industry and has considerable potential for many industrial applications.