Diagnosis of Viral infections 3 Flashcards
_________ is a diagnostic tool that amplifies viral genome/DNA
PCR
How does PCR work?
- Denaturation
- Annealing
- Extension/Elongation
What is genome sequencing?
when the sequence of bases in a DNA molecule is elucidated/ can be obtained and read
Why is genome sequencing important?
- Detects pathogens
- Studies genetic variation, genotyping, evolution, and interspecies transmission of pathogens
- ID undiscovered strains
- Development diagnostics
- ID genes associated with drug resistance
- Develop therapeutics
- Judge efficacy of vaccines
What is phylogenetic analysis?
using viral genome sequence data to study evolution of viruses and genetic relationships among viruses
In competitive ELISA, a ______ in signal when compared to assay wells with purified antigen alone indicates the presence of antigens in the sample/ a positive result
decrease
In competitive ELISA, what indicates the presence of antigens in the sample (positive result)?
Weak signal or decrease in signal = positive result
_____ is when labeled Ab are added onto a sample Ag and visible fluorescence appears at the binding sites of the specific Ab
Direct fluorescence Antibody test
_______ is when a secondary antibody labeled with fluorescent marker recognizes the primary Ab bound to Ag
Indirect fluorescence antibody test
How does immunohistochemistry work?
Applied directly on tissue
Ab tagged with enzyme, enzyme reacts w substrate to produce color change that can be seen on standard light microscope
What is immunochromatography?
- Lateral flow device
- A form of POC (point of care) test that is simple to perform, easy to carry, and does not require specialized equipment
Ex: pregnancy test
What happens in agglutination?
Uses specific antibodies to bind many antigens into single clumps to find large complexes which are easily precipitated and can be seen macroscopically or microscopically
What is agar gel immunodiffusion test?
Antigen and antibody in separate wells on an agar gel
Ag and Ab diffuse towards eachother
Thin white line is formed due to precipitation of Ag-Ab complex
How does complement fixation test result in a positive reaction?
If serum has antibodies against virus A, intact sheep RBCs will settle at the bottom
How does a complement fixation test result in a negative reaction?
If serum is negative for a virus and has no antibodies, there will be hemolysis and destruction of sheep RBCs
What are advantages of using next generation sequencing?
Cheaper, quicker, requires less DNA, and is more accurate and reliable than Sanger sequencing
What is metagenomics?
when a samples entire nucleotide sequence in analyzed by amplification and sequences of the whole genome
Powerful method for random detection of existing and new pathogens
__________ uses viral genome sequence data to study evolution of viruses and genetic relationships among viruses
Phylogenic analysis
What is a microarray?
When thousands of known DNAs are amplified by PCRs and spotted onto a glass or silicon strip
What does a positive microarray result look like?
Generates a fluorescent signal from the spot where the probe DNA is spotted in the chip
What is the advantage of using a microarray?
Hundreds of pathogens can be screened simultaneously using a single microarray chip
The study of virus evolution using genome sequence data is known as __________
Phylogenetics
_________ is a form of POC test
Immunochromatography
_________ is a method that uses bead like clumping of Antibodies
Agglutination
