Class-Cult-Purif-Quant (Ex1) Flashcards
What are the classes in the Baltimore Classification System?
Class1: DNA double stranded Class2: DNA single stranded (+) Class3: RNA double stranded Class4: RNA single stranded (+) Class5: RNA single stranded (-) Class6: DNA int. RNA single stranded (+) Class7: RNA int. DNA double stranded
What does the ICTV system consider for classification of viruses?
- nature of virus genome and virus genetic diversity
- virus replication strategies
- virus morphology
What does ICTV stand for?
International Committee on Taxonomy of Viruses
What are the suffixes for the ICTV System?
Order - virales
Family - viridae
Subfamily - virinae
Genus - virus
What are suspension cultures?
- cells which do not require attachment for growth or do not attach to the surface of the culture vessels
- can be propagated in suspension
What are monolayer cultures?
when the bottom of the culture vessel is covered with a continuous layer of cells, usually one cell in thickness
What is a primary cell culture?
- cells dissociated directly from the parental tissue of origin
- cells have same number of chromosomes as parent tissues
Disadvantages of primary cell culture
- difficult to obtain
- short lifespan in culture
- susceptible to contamination
- may not act like parent tissue
What is secondary culture?
What is a cell line?
- transfer culture
- primary culture is sub-cutlured
- transfer of cells from one culture to another
- after first subculture, primary culture becomes a cell line
Describe a fibroblastic cell
- bipolar or multipolar
- elongated shape
- grow attached to a substrate
Describe an epithelial-like cell
- polygonal shape
- grow attached to a substrate in discrete patches
Describe a lymphoblast-like cell
- spherical in shape
- grown in suspension without attaching to surface
Describe the Shell Vial technique
- cover slip with monolayer of cells
- put in media in vial, add virus, centrifuge
- when virus has grown, take out cover slip and add antibodies with fluorescent dye
- antibodies bind to virus
What are the routes of inoculation of an egg?
- Yolk sac inoculation
- Allantoic cavity inoculation
- Amniotic cavity inoculation
- Chorioallantoic membrane inoculation
Explain Rate-Zonal Centrifugation
- sample is layered
- under centrifuge, heavier particles move to the bottom
- particles of each size settle as discrete bands
Explain Isopycnic Centrifugation
- particles separated on the basis of their buoyant density
- isopycnic point is when the buoyant density of a particle equals that of the medium
What is the virus titer?
the lowest concentration of virus that still infects cells
Virus Counter 2100
- measures intact virions through detection of protein and nucleic acids
- each sample stain with two different dyes, one for nucleic acid and one for protein
- analyzed as they flow through a laser beam
Hemagglutination Assay
- add virus to RBCs in suspension
- positive: RBCs become linked by ND virus receptors and form a mat
What is a plaque?
a circular zone of necrotic cells surrounded by viable cells in a monolayer
Monolayer Plaque Assay
Units?
- measures the number of virus particles capable of forming plaques per unit volume
- plaques will be colorless
- plaque forming units/mL
Calculation for determination of the Titer(PFU/mL) for Monolayer Plaque Assay
Average titer divided by dilution
Pock Assay
Units?
- necrotic area on chorioallantoic membrane of embryonated egg
- pock-forming units/mL
Transformation Assay
Units?
- determination of titers or oncogenic viruses
- transformed cells lose contact inhibition and heap upon each other
- focus-forming units
Quantal Assay
- measures presence or absence of infection
- endpoint: virus dilution that affects 50% of test subjects
Describe Finite/Diploid Cell lines
- limited life spans and go through a limited number of cell generations
- derived from embryos or secondary cultures
- cells retain original morphology and diploid
- growth rate slow
- contact inhibition, anchorage dependence
Describe Continuous Cells lines
- divide indefinitely
- derived from cancer cells or induced transformation of primary strain
- genetically furthest from animal
- abnormal morphology and chromosome number
- rabid growth rate
- lack of contact inhibition and anchorage dependence
