Diagnosis

Question 1

Risk group 1

Answer 1

no or low individual and community risk

Question 2

Risk group 2

Answer 2

Moderate individual risk, low community risk

Question 3

Risk group 3

Answer 3

High individual risk, low communtiy risk

Question 4

Risk group 4

Answer 4

High individual and community risk

Question 5

BSL-4

Answer 5

Maximum containment laboratory
Handle dangerous and exotic pathogens belonging to highest risk group
Ebola

Question 6

Biohazard

Answer 6

Biological substances that pose a threat to the health of living organisms, primarily that of humans

Question 7

Biosafty

Answer 7

Laboratory biosafety describes the containment principles, technologies, and practices that are implemented to prevent the unintentional exposure to pathogens and toxins or their accidental release

Question 8

Aerosol

Answer 8

V small droplets of fluid that can spread via air

Viruses can spread in lab through aerosol route

Question 9

Biosecurity

Answer 9

Laboratory biosecurity describes protection, control, accountability for valuable biological materials within laboratories, in order to prevent their unauthorized access, loss, theft, misuse, diversion or intentional release

Question 10

For virus isolation

Answer 10

Specimens should be collected as soon after onset of symptoms as possible because maximal amounts (titers) of virus are usually present at onset of signs
Chance of viral recovery is best during the first 3 days after onset and is greatly reduced beyond 5 days with many viruses

Question 11

For serological tests

Answer 11

Two blood specimens are generally collected
One during acute phase of illness
second during convalescence period
Varies upon type of virus, 10-14 days after 1st sample or even more
As a general rule, specimens collected for molecular diagnostics, such as PCR, should be obtained during the early part of the illness

Question 12

Transport and storage of sample

Answer 12

Viral transport medium- swabs

Prevent spillage, follow basic triple packaging system while transporting infectious materials

Question 13

Diagnosis of viral infections by gross evaluation and histopatholgy

Answer 13

CS
Necropsy
Histopathology

Question 14

Detection of viruses by cultivation/isolation

Answer 14

Cultivation/isolation of viruses in cells/tissue culture

Inoculation in eggs

Question 15

Electron microscopy

Answer 15

Can be used to demonstrate viruses in samples and detect viruses that cannot be grown in vitro

Question 16

TEM

Answer 16

Method used in TEM based on transmitted electrons
TEM seeks to see what is inside or beyond the surface
Advantages over SEM:
-can produce images that have higher magnification and greater resolution

Question 17

SEM

Answer 17

Method used in SEM based on scattered electrons
Focuses on sample’s surface and its composition
Advantages over TEM:
- produce 3D images

Question 18

Gold standard test

Answer 18

A diagnostic test that is considered to be the most accurate and best available under a particular condition or set of condtions

Question 19

Sensitivity

Answer 19

The probability (%) that cases with the infection (determined by result of the reference or gold standard test) will have a positive result using the test under evaluation

Question 20

Specificity

Answer 20

Probability (%) that cases without the infection (determined by the result of reference or gold standard test) will have a negative result using the test under evaluation

Question 21

Collection of serum

Answer 21

Red top vacutainer tube

Question 22

Collection of plasma

Answer 22

Lavender top EDTA vautainer tube
Plasma produced when whole blood is collected in tubes that are treated with an anticoagulant. Blood does not clot in plasma tube

Question 23

typical ELISA

Answer 23

Antigen coated in well
Add antibody tagged with enzyme
Antigen binds to enzyme-tagged antibody
Wash the excess unbound antibodies
Add substrate
Enzyme tagged to antibody which is bound to antigen will change color of substrate. Intensity of color indicated more positive reaction

Question 24

Direct ELISA

Answer 24

Antigens are immobilized and enzyme conjugated primary antibodies used to detect or quantity antigen concentration
Specificity of primary antibody is v important

Question 25

Indirect ELISA

Answer 25

Primary antibodies are not labeled, but detected instead with enzyme-conjugated secondary antibodies that recognize the primary antibodies

Question 26

Sandwich ELISA

Answer 26

The antigen to be measured is bound between 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

Question 27

Competative ELISA

Answer 27

A decrease in signal when compared to assay well with purified antigen alone indicates the presence of antigens in the sample Weaker signal indicates presence of antigens in the sample- positive result

Question 28

Florescence antibody test- Direct

Answer 28

Labelled antibodies are added onto the sample (Antigen). | Visible fluorescence appears at the binding sites of the specific antibodies (antigen-antibody binding)

Question 29

Florescence antibody test- Indirect

Answer 29

Employs a secondary antibody labeled with a fluorescent marker that recognizes the primary antibody bound to antigen

Question 30

Immunohistochemistry

Answer 30

The antibody tagged with an enzyme, generally horseradish peroxidase The enzyme reacts with a substrate to produce a colored product that can be visualized in the infected cells with a standard light microscope

Question 31

Immunochromatography (lateral flow devices)

Answer 31

A form of point-of-care test that is simple to perform, easy to carry, and does not require specialized equipment like a pregnancy test

Question 32

Agglutination

Answer 32

Method using the property of specific antibodies to bind many antigens (antigens on pathogen, or antigen coated particles- latex beads) into single clumps thereby forming large complexes, which are easily precipitated The precipitation can be macroscopically or microscopically visible

Question 33

Hemagglutination and hemagglutination inhibition test

Answer 33

Relies on the property of some pathogens (mainly viruses) to nonspecifically agglutinate erythrocytes

Question 34

Agar gel immunodiffusion test

Answer 34

Ag and Ab places in separate wells of agar Diffuse toward each other Thin white line formed due to precipitation of antigen/antibody complex

Question 35

Complement fixation test

Answer 35

Serum from patient A has antibodies against virus A- intact sheep RBCs settle at bottom= positive rxn Serum from patient B has no antibodies of virus A- find hemolysis of sheep RBC= negative reaction

Question 36

Neutralization assay

Answer 36

Defined as loss of infectivity through rxn of the virus with specific antibody