virus detection and cultivation Flashcards
What are specimens used to culture or detect viruses?
throat swabs nasopharyngeal aspirates vesicle fluid blood cerebrospinal fluid saliva biopsy
What is important during transport of samples?
temperature: 4 degrees, -20 degrees, -80 degrees, -150 degrees
What are the two
What are some examples of direct detection?
electron microscopy
isolation of infectious virus by cell culture
detection of viral genome by molecular methods
detection of virions by serological methods
What is indirect detection?
measurement of virus-specific host immune response after infection
Why is electron microscopy used instead of light microscopy?
can be readily identified
How can viruses be isolated?
by propagation in animals or human cells
What is the most common method for virus propagation?
cell culture
How does cell culture work?
tissues dissociated into single cells by mechanical disruption and proteolytic enzymes
cells suspended in culture medium and placed in culture vessels
What is cell culture medium made of?
isotonic solutions of salts, glucose, vitamins and amino acid @ 7.2-7.4 pH
What are the 3 main kinds of cell cultures?
- Primary cells (5-10 cell divisions)
- Diploid cells (>100 divisions)
- Continuous cell lines (infinite)
What are evidence of viral growth?
cytopathic effects visible - inclusion bodies / morphological alterations
How can we detect viral genomes?
via PCR
How is viral antigen detected?
using immunofluorescence
How does indirect IFA work?
the antibody is labelled with a flurophore
How does indirect IFA work?
a second antibody which recognised the Fc region of the first antibody, is labelled with a flurophore
What is enzyme-linked immunosorbent assay?
a way to detect viral antigen or antiviral antibody
How does enzyme-linked immunosorbent assay work?
- antigen fixed onto a solid phase
- antigen or antibody of interest is allowed to bind
- detector antibody (conjugate) is added
- enzyme substrate added
- enzyme/substrate combinations produce a colour change
What is a way to measure infectious virus?
plaque assay
What are plaque assays?
area of killed cells in a tissue cultured vessel; visible damage can be tested
each infectious virus particle produces a circular zone called plaque
What is haemagglutination?
identifying the grouping of RBC caused by viral antigen (attachment to sialic acid)
What is a Western blot?
separation based on size, then transferred to nitrocellulose membranes (blotting) and viewed
