Molecular genetics use molecular methods that amplify specific fragments of DNA. Today, the molecular techniques which were developed for amplification and detection of specific sequences of nucleic acids helped in a great deal to understand the structure of many diseases. Polymerase chain reaction or PCR is a technique that is used for isolation and amplification of a specific sequence of DNA. PCR is an in vitro method that exploits the in vivo procedure of replication of DNA. DNA polymerase is used to amplify a piece of DNA by in vitro enzymatic replication. As PCR progresses, the DNA thus generated is itself used as a template for replication. This sets in motion a chain reaction in which the DNA template is exponentially amplified. With PCR it is possible to amplify a single or few copies of a piece of DNA across several orders of magnitude, generating millions or more copies of the DNA piece. PCR was designed and presented by Dr Kary Mullis (1983).Today PCR has a great range of implementations related to 1) the cloning and the study of gene’s expression 2) the detection of mutations that are responsible for hereditary diseases 3) Criminology, Toxicology and Forensics. / H Μοριακή Γενετική χρησιμοποιεί μοριακές μεθόδους οι οποίες ενισχύουν συγκεκριμένα τμήματα DNA. Σήμερα, οι μοριακές τεχνικές οι οποίες αναπτύχθηκαν για ενίσχυση και ανίχνευση συγκεκριμένων ακολουθιών νουκλεϊνικών οξέων βοήθησαν σε μεγάλο βαθμό στην κατανόηση της δομής πολλών ασθενειών. Η αλυσιδωτή αντίδραση πολυμεράσης είναι μια τεχνική η οποία χρησιμοποιείται για απομόνωση και ενίσχυση μιας συγκεκριμένης ακολουθίας DNA. Η αλυσιδωτή αντίδραση της πολυμεράσης είναι μια διαδικασία που πραγματοποιείται σε ελεγχόμενες συνθήκες έξω απο ζωντανούς οργανισμούς, η οποία εκμεταλλεύεται την αντιγραφή του DNA που πραγματοποιείται μεσα στον ζωντανό οργανισμό. Όσο η PCR εξελίσσεται δημιουργούνται αντίγραφα DNA χρησιμοποιώντας ως πρότυπο το αρχικό DNA. Αυτό ενεργοποιεί μια διαδικασία αλυσιδωτής αντίδρασης ώπου το DNA αναπαράγεται εκθετικά. Με την PCR μπορείς να δημιουργήσεις εκατομμύρια αντίγραφα DNA από μία συγκεκριμένη ακολουθία. Η PCR σχεδιάστηκε και παρουσιάστηκε απο τον Dr Kary Mullis. Σήμερα η PCR έχει μέγαλο εύρος εφαρμογής σε πεδία σχετικά με τη μελέτη της γενετικής έκφρασης την ανίχνευση μεταλλάξεων οι οποίες είναι υπεύθυνες για κληρονομικές ασθένειες, Εγκληματολογία, Τοξικολογία και Ιατροδικαστική.

Os contatos de pacientes com hansenÃase à um grupo de alto risco de desenvolver a doenÃa, logo a precocidade no diagnÃstico à uma importante ferramenta para o controle da enfermidade. NÃs investigamos a presenÃa de DNA de Mycobacterium leprae, atravÃs da ReaÃÃo em Cadeia Polimerase (PCR), na mucosa nasal e anticorpos anti-PGL1 sÃricos, IgG/IgM, e salivares, IgA/IgM, por meio do ensaio imunoenzimÃtico ligado à fase sÃlida (ELISA), em contatos intradomiciliares de pacientes com hansenÃase (n=135) e seus casos Ãndices. O estudo foi realizado em duas cidades endÃmicas para a doenÃa no CearÃ, Crato e MaracanaÃ. Uma boa correlaÃÃo entre os isotipos IgA e IgM salivares e IgG sÃrico foi observada quando comparou-se os contatos intradomiciliares e seus casos Ãndices (p<0,01, p<0,005 e p<0.0001, respectivamente). Entretanto, essa relaÃÃo nÃo foi observada para IgM sÃrico anti-PGL1 (p>0,05). Observou-se alta frequÃncia de IgM sÃrico anti-PGL1 no grupo de contatos negativos para IgG sÃrico anti-PGL1 (71/121, 58,6%). Dentre os contatos positivos para IgG sÃrico anti-PGL1, o nÃvel de anticorpos sÃricos IgM anti-PGL1 positivos tambÃm foi alto (10/14, 71,4%). Em relaÃÃo aos anticorpos salivares, contatos de pacientes com a forma clÃnica PB mostraram boa correlaÃÃo entre IgA e IgM (r = 0.54, p <0.0001); o mesmo foi verificado em contatos de pacientes com a forma clÃnica MB (r = 0.61, p <0.0001). Foi observado que dos contatos positivos para os anticorpos salivares anti-PGL1, 53,3% obtiveram nÃveis de anticorpos sÃricos negativos. Por outro lado, dos contatos que foram negativos para os anticorpos salivares, 71,1% obtiveram nÃveis de anticorpos sÃricos positivos. O DNA de Mycobacterium leprae foi encontrado em swabs nasais de 9 contatos de pacientes portadores da forma clÃnica MB da hansenÃase (10,6%) e em 3 contatos de pacientes portadores da forma clÃnica PB (6.0%). NÃs concluÃmos que anÃlises quantitativas de anticorpos sÃricos e salivares anti-PGL1 em contatos de pacientes com hansenÃase sÃo necessÃrias para montar estratÃgias de levantamento de infecÃÃes subclÃnicas da hansenÃase, a fim de prevenir o desenvolvimento da doenÃa. / Leprosy household contacts are group at high risk of developing the disease. We investigated the presence M. leprae DNA in nasal mucosa and anti-PGL1 serum IgG/IgM and salivary IgA/IgM antibodies from leprosy household contacts (n=135) in two endemic regions, Ceara, Brazil. Good correlation between serum IgM and IgG isotypes was observed both in MB and in PB leprosy household contacts (r = 0.39, p <0.0001). However, their levels were much different (p <0.0001). Among the contacts positive for serum IgM, 74 (87%) were found to be negative for serum IgG. In respect to the salivary antibodies, PB leprosy household contacts showed correlation between IgA and IgM (r = 0.60, p <0.0001); the same was observed in MB leprosy contacts (r = 0.77, p <0.0001). It was observed that in 75.3% of the leprosy household contacts who were positive to serum anti-PGL1, their salivary antibodies were negative. On the other hand, 50% of the leprosy household contact who were negative to serum anti-PGL1 antibodies, their salivary antibodies were positive. M. leprae DNA was found in nasal swab in 9 MB household leprosy contacts (10.6%) and in 3 PB leprosy contacts (6.0%). We concluded that quantitative analysis of serum and salivary anti-PGL1 in leprosy contacts is necessary for mounting strategies to survey subclinical leprosy infections in order to prevent development of the disease.

Leprosy household contacts are group at high risk of developing the disease. We investigated the presence M. leprae DNA in nasal mucosa and anti-PGL1 serum IgG/IgM and salivary IgA/IgM antibodies from leprosy household contacts (n=135) in two endemic regions, Ceara, Brazil. Good correlation between serum IgM and IgG isotypes was observed both in MB and in PB leprosy household contacts (r = 0.39, p <0.0001). However, their levels were much different (p <0.0001). Among the contacts positive for serum IgM, 74 (87%) were found to be negative for serum IgG. In respect to the salivary antibodies, PB leprosy household contacts showed correlation between IgA and IgM (r = 0.60, p <0.0001); the same was observed in MB leprosy contacts (r = 0.77, p <0.0001). It was observed that in 75.3% of the leprosy household contacts who were positive to serum anti-PGL1, their salivary antibodies were negative. On the other hand, 50% of the leprosy household contact who were negative to serum anti-PGL1 antibodies, their salivary antibodies were positive. M. leprae DNA was found in nasal swab in 9 MB household leprosy contacts (10.6%) and in 3 PB leprosy contacts (6.0%). We concluded that quantitative analysis of serum and salivary anti-PGL1 in leprosy contacts is necessary for mounting strategies to survey subclinical leprosy infections in order to prevent development of the disease / Os contatos de pacientes com hansenÃase à um grupo de alto risco de desenvolver a doenÃa, logo a precocidade no diagnÃstico à uma importante ferramenta para o controle da enfermidade. NÃs investigamos a presenÃa de DNA de Mycobacterium leprae, atravÃs da ReaÃÃo em Cadeia Polimerase (PCR), na mucosa nasal e anticorpos anti-PGL1 sÃricos, IgG/IgM, e salivares, IgA/IgM, por meio do ensaio imunoenzimÃtico ligado à fase sÃlida (ELISA), em contatos intradomiciliares de pacientes com hansenÃase (n=135) e seus casos Ãndices. O estudo foi realizado em duas cidades endÃmicas para a doenÃa no CearÃ, Crato e MaracanaÃ. Uma boa correlaÃÃo entre os isotipos IgA e IgM salivares e IgG sÃrico foi observada quando comparou-se os contatos intradomiciliares e seus casos Ãndices (p<0,01, p<0,005 e p<0.0001, respectivamente). Entretanto, essa relaÃÃo nÃo foi observada para IgM sÃrico anti-PGL1 (p>0,05). Observou-se alta frequÃncia de IgM sÃrico anti-PGL1 no grupo de contatos negativos para IgG sÃrico anti-PGL1 (71/121, 58,6%). Dentre os contatos positivos para IgG sÃrico anti-PGL1, o nÃvel de anticorpos sÃricos IgM anti-PGL1 tambÃm foi alto (10/14, 71,4%). Em relaÃÃo aos anticorpos salivares, contatos de pacientes com a forma clÃnica PB mostraram boa correlaÃÃo entre IgA e IgM (r = 0.54, p <0.0001); o mesmo foi verificado em contatos de pacientes com a forma clÃnica MB (r = 0.61, p <0.0001). Foi observado que dos contatos positivos para os anticorpos salivares anti-PGL1, 53,3% obtiveram nÃveis de anticorpos sÃricos negativos. Por outro lado, dos contatos que foram negativos para os anticorpos salivares, 71,1% obtiveram nÃveis de anticorpos sÃricos positivos. O DNA de Mycobacterium leprae foi encontrado em swabs nasais de 9 contatos de pacientes portadores da forma clÃnica MB da hansenÃase (10,6%) e em 3 contatos de pacientes portadores da forma clÃnica PB (6.0%). NÃs concluÃmos que anÃlises quantitativas de anticorpos sÃricos e salivares anti-PGL1 em contatos de pacientes com hansenÃase sÃo necessÃrias para montar estratÃgias de levantamento de infecÃÃes subclÃnicas da hansenÃase, a fim de prevenir o desenvolvimento da doenÃa

The etiological agent of rabies encephalitis belongs to the genus Lyssavirus in the Rhabdoviridae family. Lyssaviruses are negative sense, single stranded RNA viruses and cause an estimated 55 000 human deaths per year with 44% of these deaths occurring in Africa (WHO, 2005). With intense research effort and increased sequence information it is becoming evident that the Lyssavirus genus is much more diverse than initially thought and therefore diagnostic methods need to be modified accordingly. The African continent sustains a diverse variety of lyssaviruses, however, most countries in Africa do not have active surveillance or necessary diagnostic tools and therefore rabies-related lyssaviruses are underreported. Previous studies have indicated that real-time PCR has improved sensitivity and rapidity over conventional molecular diagnostic methods with the added advantage of allowing accurate estimations of viral load in a wide variety of samples. Several realtime PCR assays have been developed; however, none were specifically aimed at detection of lyssaviruses present on the African continent. This study was therefore aimed at evaluating certain molecular diagnostic methods for the detection of African lyssaviruses. Furthermore, the application of real-time PCR for various fields in lyssavirus research i.e. diagnostics, surveillance and pathogenicity studies were evaluated. This study revealed two different hemi-nested PCR assays capable of detecting representatives of African lyssaviruses. A real-time PCR was developed that was successful for the detection of African lyssaviruses. In addition, a quantitative assay and internal control was successfully employed for confirming ante-mortem human rabies diagnosis as well as post-mortem animal rabies diagnosis in formalin fixed brain material. As such the real-time PCR assay developed in this study could therefore be routinely used for ante-mortem diagnosis and as a confirmatory test for post-mortem diagnosis. The ability of this assay to detect and quantify all currently known African lyssaviruses not only offers improved surveillance capacity, but offers unique potential as a sensitive tool to track virus movement in pathogenicity studies. These aspects are important in our search for a better understanding of the complex epidemiological and viral characteristics of African lyssaviruses. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

>Magister Scientiae - MSc / Insertion-deletion polymorphisms (indels) have been underutilized in forensic identification of individuals in comparison with single nucleotide polymorphisms (SNPs) and short tandem repeat (STRs) systems. The use of indels for the purpose of human identification is more advantageous than previously used methods as it combines desirable characteristics of both the SNPs and STRs i.e. low costs and simplistic typing methods as well as indels having small amplicons size, making them suitable for genotyping highly degraded DNA. Currently there is only one commercial kit available for the forensic community, the Investigator® DIPlex kit (Qiagen), which cover a total of 30 indel loci distributed over 19 autosomal chromosomes. The objective of this study was to evaluate the Qiagen Investigator® DIPplex kit for forensic application in South Africa. The kit‘s performance was evaluated by comparing different extraction methods; sensitivity, robustness and reproducibility were evaluated and forensic parameters (match probability, power of discrimination, polymorphism information content, power of exclusion and typical paternity index) were estimated based on population data generated from five South African populations (Afrikaner, Mixed Ancestry, Indian-Asian, Xhosa and Zulu). Population comparisons were performed using Fst-analysis, factorial component analysis as well as phylogenetic tree construction. DNA was extracted from buccal swabs and whole blood collected from a total of 512 individuals from the five South African population groups and genotyped using the Qiagen Investigator® DIPplex kit. Sanger DNA sequencing and sequence alignments confirmed the presence of a null allele at locus HLD97 which was present in high frequency in the Xhosa and Zulu populations. This observation was made in 14 individuals belonging to the Xhosa and Zulu populations. Null allele frequencies in all five South African populations were also estimated. Null alleles were estimated for all loci using analytical methods i.e. Charkraborty null allele estimator, Brookfield null allele estimators 1 and 2 and ML-NullFreq software program. The kit performed well in the laboratory, not requiring any additional reagents or instrumentation and successfully generating profiles with input DNA amounts as low as 0.2 ng/μL. Although well suited for forensic application, the Qiagen Investigator® DIPplex kit showed some drawbacks with regards to application on South African populations. The presence of a null allele at the HLD97 locus as well as indication of population substructure affects allele frequency estimates for the South African populations. Correction for population substructure as present within the South African populations should be considered using FST analysis and it is recommended that the HLD97 locus should be excluded from any kinship analysis performed on South African populations.

Milk quality continues to be a topic of intense debate in the dairy industry, medical and public health communities. Production of maximum quantities of high-quality milk is an important goal of every dairy operation. High-quality milk must contain a low number of somatic cells and low bacteria count, and must be free of human pathogens and antibiotic residues. The objective of this study was to determine the prevalence of E. coli in unpasteurized milk recovered from Middledrift and Fort Hare dairy. In this study 400 milk samples were collected from two commercial farms (Middledrift and Fort Hare) in the Eastern Cape, South Africa, 200 raw milk samples from each farm. Samples were cultured on violet red bile mug-agar (VRB-MUG Agar) and incubated at 37ºC for 24 hours and preliminary identified by Gram stain and catalase test. Isolates that were Gram negative and catalase positive were screened for a marker of E. coli uidA gene using PCR assays. Middledrift dairy farm had 50 (25%) E. coli isolated from raw milk and Fort Hare farm showed 37 (18.5%) E. coli present in the milk samples. The presence of E. coli found in the milk samples points to the fact that fecal contamination was unavoidable and traditional practices are likely to contribute to the contamination of the milk and proliferation of the microorganisms.

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

Os pacientes infectados pelo vírus da imunodeficiência humana (HIV) freqüentemente apresentam alterações digestivas, sendo o esôfago um alvo comum de lesões estruturais. A etiologia infecciosa é a mais freqüente neste grupo de pacientes. Múltiplos agentes já foram implicados como causadores de lesões esofágicas. As infecções virais são uma das principais causas de tais lesões, sendo os vírus mais implicados o citomegalovirus (CMV) e o vírus herpes simples (HSV). Muitas lesões ulceradas permanecem sem diagnóstico etiológico, mesmo após exaustiva investigação, sendo denominadas úlceras idiopáticas ou aftosas. Os métodos de diagnóstico usuais são demorados e pouco sensíveis. Assim, nosso estudo tem como principal objetivo estudar o papel do método da reação em cadeia da polimerase (PCR) no diagnóstico destas lesões. Durante o período de outubro de 1996 a outubro de 1997, foram estudados 79 pacientes HIV-positivos, que foram submetidos ao exame de endoscopia digestiva alta por indicação clínica. Estes foram submetidos a 89 exames endoscópicos, sendo colhidas 96 biópsias, as quais foram armazenadas em nitrogênio líquido (50) ou em freezer a –70oC (46). O DNA foi extraído usando método baseado na lise hipotônica, digestão com proteinase K, extração com fenol-clorofórmio e precipitação em etanol. Uma quantidade fixa foi usada para amplificação em ciclador térmico, utilizando primers específicos para CMV, Herpesvirus, HPV, HIV, Haemophilus ducreyi, Treponema pallidum e as micobactérias M. tuberculosis, M. avium e M. intracellulare. O produto final foi submetido a uma eletroforese em gel de agarose e corado com brometo de etídeo. A endoscopia não revelou alterações esofágicas em 26 exames (29,2%). As alterações observadas foram monilíase esofágica em 33 exames (37,1%), úlceras em 22 (24,7%); esofagite em 10 (11,2%) e áreas lugol-negativas em 9 (10,1%). A PCR resultou positiva para o CMV em 19 amostras (19,8%), para o Herpes em 4 (4,2%), para o HPV em 17 (17,7%), para o HIV em 37 (38,5%) e para o H. ducreyi em 3 (3,1%). Nenhuma amostra foi positiva para o T. pallidum e para micobactérias. No estudo de 29 amostras de 22 úlceras esofágicas a PCR detectou o CMV em 9 amostras (31%), o Herpes em 3 (10,3%), o HPV em 6 (20,7%), o HIV em 19 (65,5%) e o H. ducreyi em 2 (6,9%) e em 8 (36,4%) não foi detectado nenhum agente. O CMV foi detectado com freqüência nas úlceras esofágicas, sendo difícil diferenciar se havia infecção ativa ou latente. O HIV teve uma incidência elevada nas biópsias de úlceras, o que pode sugerir um possível papel etiológico deste agente em tais lesões. O HPV foi o terceiro agente mais freqüente, mas não foi possível caracterizá-lo como causador de lesões esofágica ulceradas. A PCR apresentou potencial para tornar-se um método útil na investigação das lesões esofágicas em pacientes infectados pelo HIV. / Patients infected by Human Immunodeficiency Virus (HIV) usually present digestive abnormalities and the esophagus is a common target of structural lesions. Infections are the most frequent cause of esophageal lesions in these patients. Several agents were already implied in this process. Viral infections are one of the main causes of such lesions and cytomegalovirus (CMV) and herpes simplex virus (HSV) were the most involved agents. Many ulcerated lesions persist without etiologic diagnosis even after exhaustive investigation, being denominated idiopathic or aphthous ulcers. The usual diagnostic methods are difficult and have low sensitivity. Thus, the main objective of our study was to evaluate the role of the polimerase chain reaction (PCR) method in the diagnosis of these lesions. During the period of October of 1996 to October of 1997, 79 HIV-positive patients were studied. They were submitted to upper digestive endoscopies, which were indicated on clinical basis. These patients were submitted to 89 upper digestive endoscopies, being obtained 96 biopsies, which were stored in liquid nitrogen or in a 70oC freezer. DNA was extracted using a method based on hypotonic lyses, proteinase K digestion, extraction with phenol-chloroform and precipitation in ethanol. A fixed amount was used for amplification in thermal cycler, using specific primers for CMV, herpesvirus, human papillomavirus (HPV), HIV, Haemophilus ducreyi, Treponema pallidum, Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare. The final products were submitted to an electrophoresis in agarose gel and stained with ethidium bromide. The endoscopies did not reveal esophageal alterations in 26 exams(29,2%). The abnormalities observed were esophageal candidiasis in 33 exams (37,1%), ulcers in 22 (24,7%); esophagitis in 10 (11,2%) and lugol-negative areas in 9 (10,1%). The PCR was positive to CMV in 19 samples (19,8%), for Herpes in 4 (4,2%), for HPV in 17 (17,7%), for HIV in 37 (38,5%) and for the H. ducreyi in 3 (3,1%). No sample was positive for T. pallidum or micobacterium. In the study of the esophageal ulcers by PCR, CMV was detected in 9 samples (31%), Herpes in 3 (10,3%), HPV in 6 (20,7%), HIV in 19 (65,5%), H. ducreyi in 2 (6,9%) and any agent was detected in 8 samples (36,4%). CMV was frequently detected in esophageal ulcers, being difficult to differentiate between active and latent infections. The HIV had an elevated incidence in ulcer biopsies, which may suggest a possible etiologic role of this virus in such lesions. HPV was the third more frequent agent, but it was not possible to attribute the esophageal lesions to that virus. In conclusion, this study suggests that the PCR can be an useful method in the investigation of esophageal lesions in HIV infected patients.

Exons are expression DNA sequences. A DNA sequence which includes gene has exons and introns. During transcription and translation, introns will be removed, and exons will remain to become protein. Many researchers need exon primers for PCR experiments. However, it is a difficult to find that many exon primers satisfy all primer design constraints at the same time. Here, we proposed an efficient exon primer design algorithm. The algorithm applies multiobjective genetic algorithm (MGA) instead of the single objective algorithm which can easily lend to unsuitable solutions. And a hash-index algorithm is applied to make specificity checking in a reasonable time. The algorithm has tested by a variety of mRNA sequences. These dry dock experiments show that our proposed algorithm can find primers which satisfy all exon primer design constraints.

In polymerase chain reaction (PCR), in order to amplify massive DNA sequences successfully, it needs to design an appropriate primer pair. The constraints derived from the traits of PCR for proceeding PCR are used in searching for primer pairs. In this paper, in order to decrease the searching space and to increase the feasible quality of primers, a double orthogonal arrays intelligent crossover genetic algorithm (DOAIGA) is used to solve the primer design problem. DOAIGA combines the traditional genetic algorithm and the Taguchi methodology to efficiently search feasible primers under required constraints. The proposed intelligent crossover subsystem mainly concentrates on the better genes more systematic. The key point of DOAIGA is to achieve the elitism goal by applying the orthogonal arrays (OAs) that is used in quality engineering with a small amount of experiment features. In this thesis, the double orthogonal arrays are used to approach a better forward and reverse primers separately. Compared to the current existing softwares, DOAIGA can obtain feasible primer pairs more effectively. Finally the correctness of primer pair is verified by PCR experiment.