Diagnosis of Viral Infections Flashcards
risk group 1
no or low individual and community risk
risk group 2
moderate individual risk, low community risk
risk group 3
high individual risk, low community risk
risk group 4
high individual risk, high community risk
ex. Ebola
BSL-4
maximum containment lab
lab workers should wear one-piece, positively air-pressurized, HEPA-filtered, supplied air suit
room should be negative air-pressured
biohazard
biological substances that pose a threat to the health of living organisms, primarily that of humans
biosafety
lab biosafety describes the containment principles, technologies and practices that are implemented to prevent the unintentional exposure to pathogens
aerosol
very small droplets of fluid that can spread via air
biosafety cabinets (BSC)
an enclosed, ventilated lab workspace for safety working with materials contaminated with pathogens requiring a defined biosafety level
biosecurity
describes the protection, control and accountability for valuable biological materials in order to prevent their unauthorized access, loss, the misuse, diversion or intentional release
have to make sure you collect samples at….
the right time
the right site
from the most appropriate animal
chance of a viral recovery is best during the first _____ days
3
viral recovery is greatly reduced after _____ days
5
3 potential hazards associated with transport of pathogens
1- breakage of containers resulting in spillage
2- resulting in exposure to possible infection
3- a delay in package delivery to the diagnostic lab
clinical signs of blue tongue in sheep
cyanosis of tongue, appears purple/blue
turkey-egg shaped kidney….what disease
swine fever
what virus has the presence of negri body inclusion factors?
rabies
negative stain EM
virus is mixed with heavy metal salt solution, the mixture is then spread on a thin layer on a carbon-coated copper grid and dried…image is a negative image (see what is the background not the virus)
TEM
based on transmitted electrons. seeks to see what is inside of beyond the surface. great resolution. 2D image
SEM
based on scattered electrons. focuses on the surface and its composition. lacks resolution. 3D image.
assay
qualitative or quantitative measurment of a target entity/analytic, such as a drug or biomolecule
gold standard test
diagnostic test considered to be the most accurate and best available under a particular condition
negative predictive value
the chance that a negative test result is actually negative
positive predictive value
the chance that a positive test result is actually positive
sensitivity
probability that cases with the infection will have a positive result using the test under evaluation
specificity
probability that cases with the infection will have a negative result using the test under evaluation
serum
clear-yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. clot is removed
plasma
produced when whole blood is collected in tubes that are treated with an anticoagulant
direct ELISA
antigens are immobilized and enzymes-conjugated primary antibodies are used to detect or quantify antigen concentration.
antibody attached directly to antigen
indirect ELISA
primary antibodies are not labeled, but detect instead with enzyme-conjugated secondary antibodies that recognize the primary antibodies
antibody attached to another antibody attached to the antigen
sandwich ELISA
antigen to be measured is bound between a layer of capture antibodies and a layer of detection antibodies. the two antibodies must be very critically chosen to prevent cross-reactivity or competition of binding sites
competitive ELISA
darker the sample =more negative
lighter the sample/no color= positive
fluorescence antibody test (FAT)
antibodies are labeled with fluorescence which appears when attached to an antigen
direct FAT
visible fluorescence appears at the binding site of the specific antibodies
indirect FAT
marker recognizes the primary antibodies bound to antigen
immunohistochemistry
antibody is tagged with enzyme, generally horseradish peroxidase. enzyme reacts with substrate to create a color change within infected cells
direct assay
enzyme tagged with primary antibody that binds to antigen
indirect assay
enzyme tagged to a secondary antibody that is specific against primary antibody
immunochromatography/lateral flow devices
a form of point of care test that is simple to perform and does not require specialized equipment. sample is slid across a plate and if antibodies are present for the virus two bands will appear if not only the control line will be present
agglutination
antibodies bind to many antigens into single clumps thereby forming large complexes which are easily precipitated.
hemagglutination
virus + RBCs —> mat formation
hemagglutination inhibition
virus + RBCs + Ab —-> button formation
complement fixation test
no hemolysis = antibodies present = positive reaction
hemolysis = no antibodies = negative reaction
neutralization assay
loss of infectivity through reaction of the virus with specific antibodies
