Virology Flashcards
What can be detected relating to virus
Infectious virus isolated
Protein components
Genetic components
Host response
How could isolated virus be detected
Cell culture
Electron microscopy
What is problem of assays
Likely to give false positives and false negatives
What is sensitivity
Likelihhood of test to pick up positive results
What is specificity
Likelihood of test to pick up negative results
Samples taken for resp viruses and what test is carried out on them
Throat swab Nasopharyngeal aspirate and swab Bronchoalveolar lavage Endotracheal tube secretions PCR carried out
Samples taken for rotavirus, adenovirus and norovirus + the test carried out on them
Stool sample
PCR nad antigen detection
Samples taken for BK virus and aenovirus + test carried out on sample
Urine
PCR
Samples taken for herpes and enteroviruses + test carried out
CSF
PCR
What samples can be taken taken to carry out serology
Clotted blood
Saliva
What sample is taken for viral load testing
EDTA blood
Other than viral load testing what else can EDTA blood be used for
PCR
Process of HIV serology
4th generation EIA: Ab + p24 Ag detection
All reactive samples undergo confirmatory testing in a second assay to exclude non-specific reactivity (false positives)
Confirmed positives undergo typing (HIV 1 vs 2)
Repeat blood sample + EDTA blood for HIV viral load required from all new +ves
Problems with viral isolation in cell culture
Slow and time consuming
Only used in reference labs now
What can viral isolation in cell culture be useful for
Phenotypic antivrial susceptibility testing
Samples needed for electron microscopy
Stool and vesicle fluids
HOWEVER very rarely used
How to detect enterovirus (sample and method)
Stool and throat swab -> PCR
CNS diseases caused by viruses
Meningitis
Encephalitis
Difference in IgM and IgG
IgM produced immediately in first response and persist for 10-14 days.
IgG persists for life from during middle of first exposure
What is antibody avidity
Stability of antibody to antigen
Use of sequencing
Antiviral resistance testing
When is immunofluorescence best used
Resp infections
Disadvantages of immunofluoresce
Very skilled technician needed and good sample needed