Transcript elisa test results

A CALL TO ARMS
In the 1880s German doctor,
Robert Koch, developed a
series of methods for identifying
which organism was the cause
of a particular disease. These
postulates are still in use today.
This led the way for specific
treatment for many diseasecausing pathogens.
KOCH’S POSTULATES
Response of Immune System to Disease-Causing Organisms
A. RECOGNITION: white blood cell surrounds pathogen and signals killer T cells (not shown); more T cells
are produced; helper T cells signal B cells
B. MOBILIZATION: B cells produce antibodies
C. DISPOSAL: antibodies destroy pathogens
D. IMMUNITY: some antibodies remain for future use (memory B cells)
Antigen-Antibody Complex
• Antibodies all have the same basic Y structure
• Antibodies have different antigen binding sites designed to fit the shape
of specific antigens
• Antibodies bind to antigens like a lock and key to form the Antigen-Antibody Complex
INDIRECT ELISA (enzyme – linked immunoabsorbant assay)
• Used to detect infection by testing patients’ blood serum for the presence
or absence of antibodies against a particular pathogen
• Presence of antibodies indicates the individual has been infected and that
their body has launched an immune response against the disease-causing agent
• Test for: HIV, Avian Flu, West Nile, Lyme Disease, Smallpox, SARS, Syphilis,
Rocky Mountain Spotted Fever
Human
Immunodeficiency
Virus
Virus
responsible
for causing
Acquired
Immune
Deficiency
Syndrome
or
AIDS
Rates of Persons Aged 18–64 Years Living with a Diagnosis of HIV
Infection, Year-End 2008—United States
LYME DISEASE
Vector =
deer
tick
Reported Cases in the United States, 2012
Avian Influenza (Bird Flu)
ELISA TEST RESULTS
ELISA data from three patients. Numbers
are expressed as optical density at 450 nm.
The cutoff value indicating a positive result
is 0.500. Optical densities of 0.300 to 0.499
are indeterminate and need to be retested.
Values below 0.300 are considered to be
negative. In most cases, a patient will be
retested if the serum gives a positive result.
If the ELISA retests are positive, the patient
will then be retested by western blotting
analysis.
Positive
Negative
Control Control Patient A Patient B Patient C
1.689
0.153
O.055
0.412
1.999
Assay
Control
0.123
ELISA SIMULATION RESULTS
In this simulated ELISA, all reaction wells will turn light green when the chromogen
substrate is added. A change in color from light green to purple indicates a positive result.