Systems for Detection of Pathogens II Flashcards
What is molecular gene targeting?
β detecting a gene of gene products that are pathogen specific
What are the two techniques used for molecular gene targeting?
β NAAT
β PCR
How does PCR work?
β Two DNA primers specific for opposite strands are used to amplify the DNA region
β The product is visualised by fluorescent tags or staining in gels for an amplicon of an exact size
What does quantitative PCR measure?
β the speed at which a PCR amplicon product accumulates by the amount of fluorescence released
What two conditions is strand displacement amplification used for?
β gonorrhoea
β chlamydia
Which gene is a suitable target for chlamydia and why?
β IS711
β there are multiple copies of the same gene in every chlamydia
Why do you need more copies of H.Pylori than chlamydia to get a positive test result?
β there is only one copy of the target gene
What 5 variables need to be taken into account when doing a molecular test?
β Specificity β Reliability β Sensitivity β Accuracy β Rapidity
What is an instant bedside test useful for?
β Diagnosis of pediatric meningitis
What is a microarray?
β Ordered short nucleotide probes (40-70) attached to slides in defined spots
β each spot represents a single gene
How is comparative genomic hybridisation done?
β sample DNA and control DNA are fluorescently labelled
β they are both hybridised onto a microarray
What are the 4 advantages of tiled arrays?
β Covers the whole genome
β strand dependent
β can be used for RNA and transcriptomics
β can look for microRNA
What are the 3 ways to detect molecular signatures?
β Single gene target
β multiple gene target
β mass spectrometry
How does mass spectrometry (MALDI-TOF) work?
β Isolate organism
β Lyse with crystallizing matrixx
β Ionise and detect time of flight for each particle
β Calculate molecular weight (daltons) for each protein produced
What are the two advantages of mass spectrometry?
β Rapid
β Specific identification
