PCR Blog
Reviews and information on PCR methods, applications and technology. Tips and advice, troubleshooting, optimization and up-to-date information on the polymerase chain reaction.
The Extraction and Purification of Nucleic Acids for Analysis by PCR
from Chaminda Salgado and Waqar Hussain writing in Real-Time PCR: Advanced Technologies and Applications:
Myriad methods for the extraction and purification of nucleic acids prior to PCR are currently used throughout the community. While these methods have many unique and bespoke aspects, they broadly follow a sequence of lysis, isolation, washing and elution to get from a complex biological sample to purified nucleic acid that can be used in a PCR reaction. Various common methods available for each stage are described and potential sequences for particular sample types can be discerned. The potential for these methods to be automated are discussed and the process options summarized with respect to the speed of the methods, technical skill required and the resultant purity and yield that can be expected.
Further reading: Real-Time PCR: Advanced Technologies and Applications
Real-Time PCR book available very soon
 | Edited by: Nick A. Saunders and Martin A. Lee ISBN: 978-1-908230-22-5 Publisher: Caister Academic Press Publication Date: July 2013 Cover: hardback |
Veterinary Applications of Real-time PCR for Detection and Diagnosis of Infectious Agents
from Alan McNally writing in Real-Time PCR: Advanced Technologies and Applications:
The detection and diagnosis of veterinary infectious diseases is an area in which the potential of Real-time PCR has been best demonstrated. In particular Real-time PCR has been successfully applied as a front line tool in the diagnostic algorithm for notifiable veterinary viral pathogens such as Avian Influenza, foot-and-mouth disease, bluetongue virus, as well as rabies and Newcastle disease virus. The rapidly transmissible nature of these agents necessitates near real-time detection and diagnosis in suspected infected animals to allow implementation of control procedures. This chapter will highlight the importance of Real-time PCR in facilitating this rapid diagnosis, and the effect such rapid detection has had on containing and controlling veterinary infectious disease outbreaks.
Further reading: Real-Time PCR: Advanced Technologies and Applications
The Validation of Real-time PCR Assays for Infectious Diseases
from Melvyn Smith writing in Real-Time PCR: Advanced Technologies and Applications:
The real-time polymerase chain reaction is now established as one of the core technologies for diagnosing infectious diseases. The early stages of the technique's development were followed by a dramatic increase in the number of diagnostic assays being published, together with the introduction of commercially produced tests. Each of the numerous publications showed a number of differences in the approach to validating the newly-produced assays and in the quality and quantity of the data supporting their validation. As a result, many workers have, at times, found it difficult to reproduce the published results from other laboratories. These difficulties can arise from e.g. a lack of information in the publication, differences in equipment between laboratories, the use of different extraction methods and sequence variations in the pathogen being detected. Over the years a number of authors have voiced their concerns over the subject of what constitutes a properly validated assay, highlighting the issues of basic scientific good practice and the responsibilities of journals in publishing full validation data. This chapter summarises the recent work covering validation and verification methodology in order to provide a practical guide to help inform and standardise the process.
Further reading: Real-Time PCR: Advanced Technologies and Applications
Real-Time PCR and other Molecular Detection Methods for Foodborne Pathogenic Viruses
from Doris Helen D'Souza, Marta Hernández, Nigel Cook and David Rodríguez-Lázaro writing in Real-Time PCR in Food Science: Current Technology and Applications:
Analysis of foodstuffs for virus contamination requires profoundly sensitive and accurate methods, due to the potentially low number of viruses and the complexity of the sample matrix. In view of these criteria, the polymerase chain reaction is the assay type of choice, with its rapidity being another useful factor. Real-time PCR (qPCR) is superceding conventional PCR in several areas of molecular diagnostics, and a large variety of published qPCR-based methods for foodborne pathogen detection is available in the scientific literature. In common with other molecular-based methods, qPCR-based analysis of foodstuffs for viruses requires effective controls to ensure that issues associated with low virus numbers and the complexity of the matrix do not result in false negative or positive interpretations of results. These controls are essential for implementation of qPCR-based methods for foodborne virus detection, but in most cases are not included in those which have been published hitherto. Alternative molecular techniques, such as nucleic acid sequence-based amplification (NASBA) and loop-mediated amplification (LAMP) are also suitable for utilization in detection methods for viruses in foods, the same requirements regarding controls pertaining. All molecular-based methods for foodborne virus detection must of necessity contain sample treatment procedures to extract the virus or its nucleic acid out of the food matrix, and these procedures can be elaborate due to matrix complexity. Nonetheless efficient sample treatment methods have been devised, and in combination with molecular assays effective methods for virus analysis are now available for foods. Implementation of these methods in routine diagnostics will support food safety management programs and assist in outbreak investigation, and help to ensure a safe food supply.
Further reading: Real-Time PCR in Food Science: Current Technology and Applications
Real-time PCR Analysis of Genetically Modified Organisms
from Arne Holst-Jensen writing in Real-Time PCR in Food Science: Current Technology and Applications:
Genetic modification (GM) alters the phenotype of the GM organism (GMO). This is achieved through application of gene technology and modification of genetic information stored in nucleic acids. The logical choice of methodology to detect and characterise GM is therefore analytical methods targeting nucleic acids. The polymerase chain reaction (PCR) methodology has been the preferred methodology of this type for two decades, and the following chapter will review its applications and derivatives in relation to detection and characterisation of GM organisms (GMOs). The need for detection, identification, characterization and quantitation of GMOs depends on issues such as the legal status of the GMOs in question (authorized or not), labeling or contractual requirements, authentication, traceability and co-existence, environmental monitoring and risk assessments. The fitness for purpose of a specific analytical method is often limited to certain applications. Guidelines to establishment of analytical strategy and method selection can be very useful to those who order as well as to those who provide GMO analyses. A fundamental distinction can be made between screening and identification methods, respectively. The former may be used to group and separate putatively GMO-free samples from samples containing GMO. Both classes of methods may provide qualitative and quantitative information, but only the identification methods can provide accurate quantitation. GMO quantification is achieved almost exclusively with real-time PCR methods, but other alternatives are also available. PCR is also commonly used in combination with other techniques such as Southern blot analyses and DNA sequencing to characterize the genetic constitution of GMOs. Over the last decade extensive resources have been put into validation and critical assessment of performance characteristics and requirements for real-time PCR based GMO detection methods. GMO analyses can be particularly challenging because quantitation is required at very low concentrations, in products of highly variable nature, and where the introduced novel sequences of different GMOs belonging to the same or different species may result in misinterpretation and analytical interference. Consequently, there is a lot to learn from this field of science also for others working with real-time PCR methods. This chapter will provide several examples.
Further reading: Real-Time PCR in Food Science: Current Technology and Applications