Diagnosis of Viral Infections 1 and 2 Flashcards
No or low individual risk and No or low community risk; is which Risk group?
Risk group 1
Moderate Individual risk and Low community risk; is which Risk group?
Risk group 2
High individual Risk and Low community risk; is which Risk group?
Risk group 3
High individual risk, and High community risk; is which Risk group?
Risk group 4
A pathogen that usually causes serious human or animal disease but does not ordinarily spread from one infected individual to another. This is an example of which risk group?
Risk group 3
A pathogen that usually causes serous human or animal disease and that can be readily transmitted from one individual to another, directly or indirectly. This is an example of which risk group?
Risk group 4
Effective treatment and preventive measure are typically available in which risk group?
Risk group 3
Effective treatment and prevention measures are NOT usually available for which risk group?
Risk group 4
Which BSL # handles dangerous and exotic pathogens that belong to the highest risk group, risk group 4, such as ebola virus?
BSL- 4 (biosafety level 4)
Biological substances that pose a threat to the health of living organisms, primarily that of humans is: A. Biosecurity B. Aerosol C. Biosafety D. Biohazard
D. Biohazard
Describes the containment principles, technologies and practices that are implemented to prevent the unintentional exposure to pathogens and toxins, or their accidental release. A. Biosecurity B. Aerosol C. Biosafety D. Biohazard
C. Biosafety
Very small droplets of fluid that can spread via air. Viruses can spread in lab through this route: A. Biosecurity B. Aerosol C. Biosafety D. Biohazard
B. Aerosol
Describes the protection, control and accountability for valuable biological materials (VBM) within laboratories, in order to prevent their unauthorized access, loss, theft, misuse, diversion, or intentional release. A. Biosecurity B. Aerosol C. Biosafety D. Biohazard
A. Biosecurity
When should sample collection take place for virus isolation?
Specimens should be collected as SOON AFTER ONSET OF SYMPTOMS as possible, because maximal amounts (titers) of virus are usually present at the onset of signs.
the chance of viral recovery is best during the first _____ days after onset and is greatly reduced beyond _____ days with many viruses.
3 days; 5 days
_____ specimens are generally collected for serological tests.
two blood specimens
- one during the acute phase of illness
- the second during the convalescence period
T/F: the convalescence period varies upon type of virus; and usually is 10-14 days after the first sample collection for a serological test but could be more.
True.
As a general rule, specimens collected for _________ diagnostics, such as PCR, should be obtained during the early part of the illness.
Molecular
What should you transport swabs in?
Viral Transport Medium (VTM)
To prevent spillage, it is recommended to follow the _________ packaging system while transporting infectious materials
Basic Triple
Diagnosis of viral infections can be made via: A. clinical signs B. Necropsy C. Histopathology D. All of the above
D. All of the above
Detection of viruses can be made by all of the following EXCEPT:
A. Electron Microscopy
B. Inoculation in Eggs
C. Light Microscopy (without using a serological assay)
D. Cultivation/ Isolation of Viruses in Cell/ Tissue Culture
C. Light Microscopy
– it is not one of the listed 3 in the lecture, however if using Immunohistochemistry serological assay for detection of viruses the enzyme used in this assay reacts with a substrate to produce a colored product that can be visualized in the infected cells with a standard light microscope.
_________ microscopy can be used to demonstrate viruses in samples and detect viruses that cannot be gown in- vitro.
Electron
This method of microscopy is based on SCATTERED electrons.
SEM (Scanning Electron Microscopy)
This method of microscopy is based on TRANSMITTED electrons.
TEM (Transmission Electron Microscopy)
This method of microscopy focuses on the sample’s surface and its composition.
SEM
This method of microscopy seeks to see what is inside or beyond the surface.
TEM
T/F: SEM produces 2D images, while TEM produces 3D images.
FALSE!!!
- SEM produces 3D images
- -TEM produces 2D images
T/F: TEM has higher magnification and greater resolution than SEM.
True!
A diagnostic test that is considered to be the most accurate and best available under a particular condition or set of conditions.
Gold Standard Test
The probability (percentage) that cases with the infection (determined by the result of the reference or ‘gold standard’ test) will have a POSITIVE result using the test under evaluation.
Sensitivity
The probability (percentage) that cases with the infection (determined by the result of the reference or ‘gold standard’ test) will have a NEGATIVE result using the test under evaluation.
Specificity
What should you collect BLOOD in?
A. Red- Top Vacutainer Tube
B. Lavender/ Purple Top EDTA Vacutainer Tube
A. Red- Top Vacutainer Tube
What should you collect PLASMA in?
A. Red- Top Vacutainer Tube
B. Lavender/ Purple Top EDTA Vacutainer Tube
B. Lavender/ Purple Top EDTA Vacutainer Tube
______ is produced when blood is collected in tubes that are treated with an anticoagulant and the blood therefore does not clot in this tube.
A. Serum
B. Plasma
B. Plasma
The 6 steps of a typical ELISA are:
- Antigen coated in the well
- Add antibody tagged with an 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.
In a typical ELISA, the intensity of color indicates a more ( positive or negative? ) reaction.
Positive
Antigens are immobilized and enzyme- conjugated PRIMARY antibodies are used to detect or quantify antigen concentration. The specificity of the primary antibody is very important. The above describes: A. Sandwich ELISA B. Direct ELISA C. Competitive ELISA D. Indirect ELISA
B. Direct ELISA
Primary antibodies are not labeled, but detected instead with enzyme- conjugated SECONDARY antibodies that recognize the primary antibodies. The above describes: A. Sandwich ELISA B. Direct ELISA C. Competitive ELISA D. Indirect ELISA
D. Indirect ELISA
The 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. The above describes: A. Sandwich ELISA B. Direct ELISA C. Competitive ELISA D. Indirect ELISA
A. Sandwich ELISA
A DECREASE IN SIGNAL when compared to assay well with purified antigen alone indicates the presence of antigens in the sample. The above describes: A. Sandwich ELISA B. Direct ELISA C. Competitive ELISA D. Indirect ELISA
C. Competitive ELISA
In competitive ELISA, a (weaker or stronger?) signal indicates the presence of antigens in a sample, i.e. a positive result?
Weaker signal = positive result for Competitive ELISA
What are the two types of FAT’s (Fluorescence Antibody Test’s)?
1) Direct FAT
2) Indirect FAT
Labelled antibodies are added onto the sample (antigen). Visible FLUORESCENCE appears at the binding sites of the specific antibodies (antigen- antibody binding). This process describes which serological Assay?
Direct FAT (Fluorescence Antibody Test)
This serological assay employs a SECONDARY antibody labeled with a FLUORESCENT marker that recognizes the primary antibody bound to antigen.
Indirect FAT (Fluorescence Antibody Test)
In this serological assay the antibody is 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.
Immunohistochemistry
In this serological assay a form of POC (Point- of- Care) test is simple to perform, easy to carry, and does not require specialized equipment. (examples are HIV and Pregnancy tests)
Immunochromatography (Lateral Flow Devices)
In this serological assay, a 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).
Agglutination
In this serological assays both methods rely on the property of some pathogens (mainly viruses) to nonspecifically agglutinate erythrocytes.
Hemagglutination and Hemagglutination Inhibition Test
In this serological assay antigen and antibody are placed in separate wells of an agar gel. Antigen and antibody diffuse toward each other. A thin white line is formed due to precipitation of antigen/ antibody complex.
Agar Gel Immunodiffusion Test
In this serological assay If a patient serum has antibodies against virus A intact RBCs will settle at the bottom of the tube indicating a positive reaction. If a patient serum is negative/ has no antibodies for Virus A there will be no antibodies –> Hemolysis/ Destruction of RBCs will yield a negative reaction.
Complemnet Fixation Test
In a Complemnet Fixation Test, if a patient serum has antibodies against virus A intact RBCs will settle at the bottom of the tube indicating a (positive or negative?) reaction.
Positive
In a Complemnet Fixation Test, if a patient serum has no antibodies for Virus A there will be no antibodies –> Hemolysis/ Destruction of RBCs will yield a (positive or negative?) reaction.
Negative
Which of the following are examples of Serological Assays for Detecting Viral Infections?
A. ELISA
B. Fluorescence Antibody Test (FAT)
C. Immunohistochemisty
D. Immunochromatography
E. Agglutination
F. Hemagglutination and Hemagglutination Inhibition Test
G. Agar Gel Immunodiffusion Test
H. Complement Fixation Test
I. All of the above are examples of Serological Assays for Detecting Viral Infections
I. All of the above are examples of Serological Assays for Detecting Viral Infections
___________ of a virus is defined as the loss of infectivity through reaction of the virus with specific antibody.
Neutralization
