Francisella tularensis is the causative agent of the debilitating, sometimes fatal zoonotic disease tularemia. To date, little information has been available on the genetic makeup of this pathogen, its evolution, and the genetic differences which characterize subspecific lineages. These are the main areas addressed in this thesis. The work indicated a high degree of genetic conservation of F. tularensis, both on the sequence level as determined by sequencing and on the compositional level, determined by array-based comparative genomic hybridizations (aCGH). One striking finding was that subsp. mediasiatica was most similar to subsp. tularensis, despite their natural confinement to Central Asia and North America, respectively. All genetic Regions of Difference RD found by aCGH distinguishing lineages were had resulted from repeat-mediated excision of DNA. This was used to identify additional RDs. Such data along with a multiple locus sequence analysis suggested an evolutionary scenario for F. tularensis. Based on genomic information, a novel typing scheme for F. tularensis was furthermore devised and evaluated. This method provided increased robustness compared to previously used methods for F. tularensis typing, while retaining a capacity for high resolution. Finally, the genomic sequence of the highly virulent F. tularensis strain SCHU S4 was determined and analysed. Evidenced by numerous pseudogenes and disrupted metabolic pathways, the bacterium appears to be undergoing a genome reduction process whereby a large proportion of the genetic capacity gradually is lost. It is likely that F. tularensis has irreversibly has evolved into an obligate host-dependent bacterium, incapable of a free-living existence. Unexpectedly, the bacterium was found to be devoid of common virulence mechanisms such as classic toxins, or type III and IV secretion systems. Instead, the virulence of this bacterium is probably largely the result of specific and unusual mechanisms.

A general aim was to combine molecular typing methods with clinical background information to increase epidemiological knowledge about Chlamydia trachomatis infections. An outbreak of Lymfogranuloma venereum (LGV), caused by a more invasive variant of C. trachomatis, was reported from the Netherlands in 2003 among men who have sex with men (MSM). All Chlamydia positive specimens from a venereal disease clinic for MSM in Stockholm during one year were genotyped. No spread of LGV was found, apart from three symptomatic cases. The same ompA genotypes were found among MSM in Melbourne, but the genotype distribution was different compared to findings among the heterosexual population in Sweden. The standard method for genotyping of Chlamydia is ompA-sequencing, but it has low resolution because one genotype predominates. A multilocus sequence typing (MLST) system based on five targets was developed. In a sample of 47 specimens, 32 variants were found with MLST, but only 12 variants with ompA-sequencing. The polymorphisms in the hctB gene, one MLST target, are caused by an element of 108 bp that is present in two to four repetitions and in different variants. Although the DNA-binding function of Hc2 that is encoded by hctB has been studied, our findings of a considerable size variation show that new studies are needed. In 2006, specimens with a 377 bp deletion in the cryptic plasmid covering the target region for diagnostic test systems from Abbott and Roche were discovered in Sweden. Applying MLST to these specimens indicated that there was a single clone, denoted nvCT. The proportion of nvCT in all detected Chlamydia cases was higher (20% to 65%) in counties using Abbott/Roche compared to counties using the BectonDickinson test system (7% to 20%). The proportions of nvCT converge in counties with high or low levels when detection systems were adjusted to detect nvCT.

Los resultados de esta tesis doctoral han permitido profundizar en el reconocimiento y clasificación del linfoma de células del manto (MCL), basándonos en dos subtipos poco habituales. Por un lado, hemos estudiado las muestras de los pacientes de MCL que no presentan la traslocación principal t(11;14), característica que ha sido objeto de discusión al pensar que el diagnóstico de MCL podía no ser el correcto. Por otro lado, hemos estudiado los MCL con presentación clínica indolente, larga supervivencia, y que no requieren tratamiento durante largos períodos de tiempo, particularidad llamativa en los pacientes de MCL. En las dos primeras publicaciones de esta tesis hemos profundizado en el estudio de los MCL ciclina D1 negativos. Hemos demostrado que el factor de transcripción SOX11, además de sobreexpresarse en MCL ciclina D1 positivos, es un biomarcador útil para identificar los MCL ciclina D1 negativos. Además, caracterizamos genéticamente estos casos y mostramos que el 55% presenta traslocaciones de la CCND2 predominantemente con cadenas ligeras de los genes de las inmunoglobulinas. El perfil de alteraciones genómicas estudiado con arrays de alta densidad ha demostrado que las alteraciones genéticas secundarias entre los MCL ciclina D1 negativos y positivos son muy similares. Los casos de MCL ciclina D1 negativos tienen características clínicas y patológicas similares a los ciclina D1 positivos. Las translocaciones de CCND2 junto con la expresión de SOX11 son herramientas de diagnóstico muy útiles en la identificación de los MCL ciclina D1 negativos para que éstos puedan beneficiarse de los mismos protocolos terapéuticos usados en los MCL convencionales. En el tercer trabajo de esta tesis, nos hemos centrado en el reconocimiento del grupo de pacientes de MCL que no necesita tratamiento durante largos periodos de tiempo, idea que está modificando la manera de entender el MCL, ya que en general está considerado un linfoma agresivo que requiere un tratamiento inmediato. En este trabajo nos basamos en el estudio de Fernandez et al.1 en que se comparó un grupo de pacientes de MCL con comportamiento clínico indolente con un grupo de pacientes con MCL convencional (agresivo). Ambos grupos de muestras tenían un perfil de expresión global similar, sugiriendo que pertenecen a la misma enfermedad, pero también diferían en la expresión de una pequeña firma de 13 genes que estaba altamente expresada en los casos convencionales de MCL pero era negativa en los tumores de los pacientes con comportamiento indolente. Por lo que en el presente estudio, diseñamos y validamos un ensayo de PCR cuantitativa, seleccionando tres genes de la firma de perfil de expresión génica: SOX11, HDGFRP3 y DBN1 que permiten clasificar los casos en uno de estos dos grupos. El subgrupo con baja expresión de los tres genes incluye principalmente los pacientes con clínica indolente, afectación no-ganglionar, genes de las inmunoglobulinas hipermutados, y una supervivencia significativamente superior en comparación a los casos con expresión alta. Además, los MCL leucémicos sin afectación ganglionar y con alta expresión de los tres genes tienen una supervivencia significativamente inferior y un comportamiento clínico más agresivo que los pacientes con firma de expresión baja sin afectación ganglionar. En cuanto a las alteraciones genéticas, tanto los MCL con alta o baja expresión de los tres genes tenían una supervivencia significativamente inferior si presentan alteraciones en 17p. Por tanto, concluimos que la evaluación de la firma de los tres genes junto con el estudio de 17p/TP53 en muestras leucémicas puede ayudar a identificar un subgrupo particular de MCL y determinar la evolución clínica de estos los pacientes. Por tanto, estos estudios pueden proporcionar una evaluación más precisa del MCL y una ayuda en la decisión de tratamiento más adecuado para cada paciente. / In the first publication of this thesis we have studied the cyclin D1-negative mantle cell lymphomas (MCL). These cases are not well characterized due to the difficulties in their recognition. Overexpression of the transcription factor SOX11 has been observed in conventional MCL. In this study we demonstrated that SOX11 was highly expressed in cyclin D1-negative MCL, thus SOX11 expression is a highly specific marker for both cyclin D1-positive and negative MCL. In the second study we investigated 40 cyclin D1-negative MCL. Chromosomal rearrangements of CCND2 were detected in 55% of the cases and frequently with light chain immunoglobulin (IG) genes as partners. The genomic profile of the cyclin D1-negative cases analyzed by high resolution arrays were similar to the cyclin D1-positive MCL. This characterization of a large series of cyclin D1-negative MCL indicates that these tumors are clinically and biologically similar to the cyclin D1-positive MCL and provides a basis for the proper identification and clinical management of these patients. In the third publication, we studied the clinical and biological features of mantle cell lymphoma with a more indolent disease and long survival. The expression of 3 genes (SOX11, HDGFRP3, DBN1) selected from a gene expression signature distinguishing conventional an indolent MCL was studied in 68 leukemic MCL by quantitative PCR. An unsupervised analysis segregated two groups of MCL based on the expression levels of these genes. The tumors with low expression presented mainly with a non-nodal disease, had more frequently mutated IG, fewer genomic alterations, remained untreated more frequently and longer time, and had a better outcome than the tumors with high expression. The presence of 17p/TP53 alterations had an adverse effect on the outcome of both subgroups of MCL. The detection of the 3-gene signature may help to identify this particular subtype of MCL.

DNA arrays have become a major bioanalytical method as they enable high-throughput screening and they can be manufactured on different surfaces depending on the nature of diagnostic purpose. However, current technologies to produce and detect arrays of DNA probes are expensive due to the requirement of specialized instrumentation. In this study we have established an array platform in sandwich hybridization format for the detection of label-free nucleic acid targets. Unlike direct hybridization, which is the main microarray hybridization principle, sandwich assay enables unlabeled target detection, lowering the cost and assay time. To this end, sequence specific signal development was achieved by a sandwich complex which is composed of a surface immobilized capture DNA probe (Probe1) and a fluorescein-tagged signal DNA probe (Probe 2), which are partially complementary to the sequence to be analyzed (target oligonucleotide). As the solid support of the array platform both 3-aminopropyl-3-methoxysilane (APTMS) activated and commercially purchased poly-L lysine coated glass slides were used and due to the less background noise property the latter one was preferred. Similarly, for the immobilization of the capture Probe (P1) onto the solid support two different methods were tried / heat immobilization and immobilization via a heterobifunctional cross-linker (HBCL). In regard to the experiments, it is observed that using a cross-linker instead of heat immobilization reduces the ratio of false negative control results in a significant manner. Following the solid support and immobilization method choice comparative optimization studies which include cross-linker type, probe concentration, sensitivity of the platform and hybridization conditions (sequence, temperature and duration) were conducted. Optimum hybridization signal was obtained with a 32.5

Staphylococcus aureus has long been recognized as a leading cause of nosocomial infection. However, several recent publications have demonstrated this pathogen as the cause of community-acquired severe wound infections and necrotizing pneumonia in otherwise healthy individuals. These highly virulent endemic clones have been reported in several locations in the United States and Canada. The rapid spread of the organism, the ability of certain clones to cause serious infection, and the antibiotic resistance of the endemic clones, illustrates the importance of infection control measures. In this study we examined three S. aureus typing techniques; pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and Staphylococcal protein A (spa) sequencing for subspeciation of community-acquired methicillin-resistant S. aureus (CA-MRSA). It is hypothesized that PFGE will result in a higher level of discrimination among the strains, while MLST and spa typing will result in highly portable data that lacks the discriminatory power of PFGE. Thirty CA-MRSA isolates that were obtained from Florida and Washington State were characterized by molecular typing methods. Whole genome restriction analysis was performed by PFGE using the SmaI enzyme. Sequence-based typing analyses, MLST and spa typing, were performed by polymerase chain reaction (PCR) followed by sequencing. PFGE data was analyzed using the BioNumerics® software package and sequence-based data was analyzed using DNAstar®. MLST Alleles were assigned using the online MLST database (www.mlst.net) and spa types were assigned using the Ridom SpaServer (www.ridom.de/spaserver). Molecular characterization of the 30 isolates resulted in 21 pulsotypes, four MLST sequence types (STs), and six spa types. Combining data from both MLST and spa typing resulted in only seven strain categories, many of which grouped isolates that are not epidemiologically linked. These data demonstrate that techniques such as MLST and spa typing are not well suited for tracking isolates with limited evolutionary diversity such as the CA-MRSA epidemic clones.

<p>Initially, a pilot study was carried out in order to reconstruct the major paternal and maternal lineages of the Muslim population living in the Cape metropolitan area. The Study has shown the ability of molecular genetic tools to give insight into the origins and history of local communities. The study was also used as a point of reference for the Strand Muslim Community project. Genetic variations of the Y-chromosome and mitochondrial DNA for the pilot study were analyzed using the RFLP technique. The SNaPshot mini-sequencing technique was used to genotype single nucleotide polymorphisms (SNP) on the Y-chromosome and mitochondrial DNA in 115 males from the Strand Muslim community.</p>

Group A rotaviruses are a major cause of acute gastroenteritis in children. Almost all children are infected by the age of 5 years old. Rotavirus disease causes around 600,000 deaths per year. VP4 (P) and VP7 (G) genotypes were analyzed for prevalence and potential antigenicity, as they are known to elicit a neutralizing antibody response during infection. This study predicted the effectiveness of two recently licensed rotavirus vaccines based on Canadian surveillance. 271 out of 348 diarrhea samples from 8 paediatric hospital were successfully genotyped by PCR. Canadian rotavirus genotypes were found to be mostly G1P[8] followed by G3P[8], G2P[4], G9P[8], G4P[8], and G9P[4], between 2007 and 2010. Reassortment and motif analysis was done with a subset of rotavirus-positive samples. There were no unusual reassortment events found in Canadian strains. Variations amongst strains were commonly genotype-specific, but otherwise rare. In conclusion, rotavirus vaccine escape is presently unlikely amongst Canadian strains.

A current trend in biological science is the increased use of computational tools for both the production and analysis of experimental data. This is especially true in the field of genomics, where advancements in DNA sequencing technology have dramatically decreased the time and cost associated with DNA sequencing resulting in increased pressure on the time required to prepare and analyze data generated during these experiments. As a result, the role of computational science in such biological research is increasing. This thesis seeks to address several major questions with respect to the development and application of single nucleotide polymorphism (SNP) resources in non-model organisms. Traditional SNP discovery using polymerase chain reaction (PCR) amplification and low-throughput DNA sequencing is a time consuming and laborious process, which is often limited by the time required to design intron-spanning PCR primers. While next-generation DNA sequencing (NGS) has largely supplanted low-throughput sequencing for SNP discovery applications, the PCR based SNP discovery method remains in use for cost effective, targeted SNP discovery. This thesis seeks to develop an automated method for intron-spanning PCR design which would remove a significant bottleneck in this process. This work develops algorithms for combining SNP data from multiple individuals, independent of the DNA sequencing platforms, for the purpose of developing SNP genotyping arrays. Additionally, tools for the filtering and selection of SNPs will be developed, providing start to finish support for the development of SNP genotyping arrays in complex polyploids using NGS. The result of this work includes two automated pipelines for the design of intron-spanning PCR primers, one which designs a single primer pair per target and another that designs multiple primer pairs per target. These automated pipelines are shown to reduce the time required to design primers from one hour per primer pair using the semi-automated method to 10 minutes per 100 primer pairs while maintaining a very high efficacy. Efficacy is tested by comparing the number of successful PCR amplifications of the semi- automated method with that of the automated pipelines. Using the Chi-squared test, the semi-automated and automated approaches are determined not to differ in efficacy. Three algorithms for combining SNP output from NGS data from multiple individuals are developed and evaluated for their time and space complexities. These algorithms were found to be computationally efficient, requiring time and space linear to the size of the input. These algorithms are then implemented in the Perl language and their time and memory performance profiled using experimental data. Profiling results are evaluated by applying linear models, which allow for predictions of resource requirements for various input sizes. Additional tools for the filtering of SNPs and selection of SNPs for a SNP array are developed and applied to the creation of two SNP arrays in the polyploid crop Brassica napus. These arrays, when compared to arrays in similar species, show higher numbers of polymorphic markers and better 3-cluster genotype separation, a viable method for determining the efficacy of design in complex genomes.

Group A rotaviruses are a major cause of acute gastroenteritis in children. Almost all children are infected by the age of 5 years old. Rotavirus disease causes around 600,000 deaths per year. VP4 (P) and VP7 (G) genotypes were analyzed for prevalence and potential antigenicity, as they are known to elicit a neutralizing antibody response during infection. This study predicted the effectiveness of two recently licensed rotavirus vaccines based on Canadian surveillance. 271 out of 348 diarrhea samples from 8 paediatric hospital were successfully genotyped by PCR. Canadian rotavirus genotypes were found to be mostly G1P[8] followed by G3P[8], G2P[4], G9P[8], G4P[8], and G9P[4], between 2007 and 2010. Reassortment and motif analysis was done with a subset of rotavirus-positive samples. There were no unusual reassortment events found in Canadian strains. Variations amongst strains were commonly genotype-specific, but otherwise rare. In conclusion, rotavirus vaccine escape is presently unlikely amongst Canadian strains.

Comprehensive characterisation of the mutational landscapes of solid tumours is a multistep process involving the collection of suitable samples, the extraction of nucleic acids and the preparation of these materials for mutational analyses. In this thesis, I aimed to develop a streamlined process for the analysis of colorectal cancer (CRC) patient samples in order to identify novel mutations that hallmark the development of advanced disease. Papers I and II outline a technique for serial extraction of nucleic acids from frozen tissue that we developed and subsequently implemented on a robotic platform to enable high-throughput processing. The extracted nucleic acids were validated in downstream processes relevant for genetic analyses, including traditional Sanger and next generation sequencing  techniques. In Paper III, we developed a genotyping method based on multiplex ligation-dependent genome amplification. The method was designed such that InDel polymorphisms of between 30 and 70 % prevalence in a European population were selected and amplified in a multiplex PCR assay. DNA from 24 patient-matched colorectal tumour and normal tissues was genotyped and paired with a high match probability. In Paper IV, we performed targeted resequencing of 107 primary CRCs, of which approximately half developed metastatic disease or had distant metastases at the time of diagnosis. We chose to analyse 676 genes based on their involvement in key signalling pathways in CRC. We found an enrichment of mutations in the Eph receptor tyrosine kinase gene family in metastatic patients, indicating a potential role for these genes in CRC metastasis. This thesis outlines a series of procedures that can be employed in a high-throughput setting for the analysis of solid tumours. We applied these methods to the analysis of colorectal tumours and propose a link between novel somatic mutations and metastatic disease.