Term
|
Definition
| administration of a vaccine so that the patient actively mounts a protective immune response |
|
|
Term
|
Definition
| individual acquires immunity through the transfer of antibodies formed by an immune individual or animal |
|
|
Term
|
Definition
• The Chinese noticed that children who recovered from smallpox did not contract the disease a second time
• They infected young children with material from a smallpox scab to induce immunity in these children, a process known as variolation
• The use of variolation spread to England and America but was eventually stopped due to the risk of death
• Edward Jenner found that protection against smallpox could be induced by inoculation with material from an individual infected with cowpox, a similar but much milder disease |
|
|
Term
|
Definition
• Since the Latin word for cow is vacca, this process was called vaccination, and the inoculum was termed a vaccine
• Louis Pasteur developed a vaccine against Pasteurella multocida
• Practice of transferring protective antibodies was developed when it was discovered that vaccines protected through the action of antibodies |
|
|
Term
|
Definition
• 3 general types of vaccines
– Attenuated live
– Inactivated (killed), whole or subunit
– Toxoid |
|
|
Term
|
Definition
• Also called modified live vaccines
• Uses pathogens that are living but have reduced virulence so they don’t cause disease
• Attenuation is the process of reducing virulence
– Viruses often attenuated by raising them in tissue culture cells for which they aren’t adapted until they lose the ability to produce disease
– Bacteria can be made avirulent by culturing under unusual conditions (BCG) or through genetic manipulation |
|
|
Term
|
Definition
• Can result in mild infections but no disease in normal individual
• Contain replicating microbes that can stimulate a strong immune response due to fact that it is an actual infection
• Viral vaccines trigger a cell-mediated immune response dominated by TH1 and cytotoxic T cells
• Vaccinated individuals can infect those around them, providing herd immunity |
|
|
Term
| Problems with Attenuated Vaccines |
|
Definition
• Attenuated microbes may retain enough virulence to cause disease, especially in immunosuppressed individuals
• Pregnant women should not receive live vaccines due to the risk of the modified pathogen crossing the placenta
• Modified viruses may occasionally revert to wild type or mutate to a virulent form |
|
|
Term
|
Definition
• Can be either whole agent vaccines produced with deactivated but whole microbes, or subunit vaccines produced with antigenic fragments of microbes
• Both types are safer than live vaccines since they cannot replicate or mutate to a virulent form
• When microbes are killed, one must not alter the antigens responsible for stimulating protective immunity
• Formaldehyde is commonly used to inactivate microbes by cross-linking their proteins and nucleic acids
• Usually recognized as exogenous antigens and stimulate a TH2 response that promotes antibody-mediated immunity |
|
|
Term
| Problems with Inactivated Vaccines |
|
Definition
• Do not stimulate herd immunity
• Whole agent vaccines may stimulate an inflammatory response due to nonantigenic portions of the microbe
• Weak immunogenicity, since the microbes don’t reproduce and are cleared before they stimulate a strong immune response |
|
|
Term
| Problems with Inactivated Vaccines |
|
Definition
• Administration in high or multiple doses, or the incorporation of an adjuvant, can make the vaccine more effective
– Adjuvants are substances that increase the immunogenicity of the vaccine
– Adjuvants may also stimulate local inflammation
– High and multiple vaccine doses may produce allergic reactions |
|
|
Term
Some Common Adjuvants
Toxoid Vaccines |
|
Definition
• Chemically or thermally modified toxins used to stimulate active immunity
• Useful for some bacterial diseases
• Stimulate antibody-mediated immunity
• Require multiple doses because they don’t replicate in the host and are cleared quickly |
|
|
Term
Adult Immunization Schedule
Modern Vaccine Technology |
|
Definition
• Research attempts to make vaccines that are more effective, cheaper, and safer
• A variety of recombinant DNA techniques can be used to make improved vaccines |
|
|
Term
|
Definition
• Problems associated with vaccination
– Mild toxicity is the most common problem
• Especially seen with whole agent vaccines that contain adjuvants
• May cause pain at the injection site and in rare cases can cause general malaise or fever high enough to induce seizures
– Anaphylactic shock
• Is an allergic reaction that may develop to a component of the vaccine |
|
|
Term
|
Definition
– Residual virulence
• Attenuated viruses occasionally cause disease in healthy children or adults
– Allegations that certain vaccines against childhood diseases cause or trigger autism, diabetes, and asthma
• Research has not substantiated these allegations |
|
|
Term
|
Definition
• Administration of preformed antibodies to a patient
• Used when protection against a recent infection or an ongoing disease is needed quickly
• Immunologists remove the serum from human or animal donors that have been infected with the disease or immunized against it
• Serum used for passive immunizations is called antiserum |
|
|
Term
|
Definition
• Contain antibodies against many different antigens not just the ones of interest
• Repeated injections of antisera collected from a different species can trigger allergic reactions
• Antisera may be contaminated with viral pathogens
• Antibodies of antisera are degraded relatively quickly
• Some of these limitations have been overcome through the development of hybridomas and monoclonal antibodies |
|
|
Term
|
Definition
• Serology = study and diagnostic use of antigen-antibody interactions in blood serum
• Use immunological processes in two general diagnostic ways
– Use known antibodies to detect antigens associated with an infectious agent
– Use antigens to detect specific antibodies in a patient’s blood to determine exposure to a specific pathogen
• Test chosen based on the suspected diagnosis, cost to perform the test, and the speed with which a result can be obtained |
|
|
Term
|
Definition
• Numerous types of serologic test
– Precipitation tests
– Agglutination tests
– Neutralization tests
– Labeled antibody tests |
|
|
Term
|
Definition
• One of the easiest of serological tests
• Based on the idea that soluble antigens and antibody mixed in the proper proportion form large macromolecular complexes called precipitates |
|
|
Term
| Antigen and Antibody Proportions |
|
Definition
• Correct proportions are important to create precipitation
• Insure optimal antibody and antigen concentrations using 2 techniques:
– Immunodiffusion
– Immunelectrophoresis |
|
|
Term
|
Definition
• Commonly used to measure the concentrations of specific antibodies or immunoglobulins in a person’s serum
• Produce anti-antibodies by injecting human antibodies (of 1 class) into an individual of another species where they will be antigenic and cause production of antibodies directed against the human antibodies
• The human antibodies are the “antigen” in the test, and the anti-antibody is the antibody |
|
|
Term
|
Definition
• Improves the resolution of an immunodiffusion test
• Can resolve more than 30 distinct antigens at once
• Commonly used to demonstrate the absence of a normal antigen or to detect the presence of excessive amounts of an antigen |
|
|
Term
|
Definition
• Agglutination occurs due to the cross-linking of antibodies with particulate antigens
• Agglutination is the clumping of insoluble particles, whereas precipitation involves the aggregation of soluble molecules
• These reactions are easy to see and interpret with the unaided eye
• Hemagglutination, the agglutination of red blood cells, can be used to determine blood type |
|
|
Term
|
Definition
• Based on the concept that antibodies can neutralize biological activity of many pathogens and their toxins
• 2 Neutralization tests:
– Viral neutralization
– Viral hemagglutination inhibition test |
|
|
Term
|
Definition
• Viruses introduced into appropriate cell cultures will invade and kill the cells, a phenomenon called cytopathic effect
• The ability of a virus to kill culture cells is neutralized when the virus is first mixed with antibodies against it
• Absence of cytopathic effect indicates the presence of antibodies against the virus
• Test is sensitive and specific enough to identify whether an individual has been exposed to a particular virus or viral strain |
|
|
Term
| Viral Hemagglutination Inhibition Test |
|
Definition
• Useful for viruses that aren’t cytopathic
• Test based on viral hemagglutination, the ability of some viral surface proteins to clump red blood cells
• Serum from an individual will stop viral hemagglutination if the serum contains antibodies against the specific virus
• Commonly used to detect antibodies against influenza, measles, and mumps viruses |
|
|
Term
|
Definition
• Use antibody molecules that are linked to some molecular “label” that enables them to be easily detected
• Used to detect either antigens or antibodies
• 3 examples
– Fluorescent antibody tests
– ELISA
– Western blot test |
|
|
Term
| Fluorescent Antibody Test |
|
Definition
• Uses fluorescent dyes as labels
• Fluorescein is the most important dye used in these tests
– Chemically linked to an antibody without affecting antibody’s ability to bind antigen
– Glows bright green when exposed to fluorescent light
• Fluorescein-labeled antibodies used in 2 types of tests
– Direct fluorescent antibody test
– Indirect fluorescent antibody tests |
|
|
Term
| Direct Fluorescent Antibody Tests |
|
Definition
• Identifies the presence of antigen in tissue
– Tissue sample flooded with labeled antibody
– Antibody and antigen are allowed to bind for a short period
– Unbound antibody washed from the preparation
– Results observed under a fluorescent microscope
• Used to identify small numbers of bacteria in patient tissues
• Not a quantitative test- the amount of fluorescence observed is not directly related to the amount of antigen present |
|
|
Term
| Indirect Fluorescent Antibody Tests |
|
Definition
• Similar to direct test, except 2 antibodies are used; the first is unlabeled and detects antigen of interest; the second is labeled and detects the first antibody
• Advantage is that the same labeled anti-antibody can be used in many different detection tests |
|
|
Term
| Indirect Fluorescent Antibody Tests |
|
Definition
• Similar to direct test, except 2 antibodies are used; the first is unlabeled and detects antigen of interest; the second is labeled and detects the first antibody
• Advantage is that the same labeled anti-antibody can be used in many different detection tests |
|
|
Term
|
Definition
• Stands for Enzyme-Linked Immunosorbent Assay
• Uses an enzyme as the label
– Reaction of the enzyme with its substrate produces a colored product indicative of antibody presence
• Most common form of ELISA is used to detect the presence of antibodies in serum |
|
|
Term
|
Definition
• Modification of the ELISA technique
• Commonly used to detect antigen
• Antigen being tested for is “sandwiched” between two antibody molecules |
|
|
Term
|
Definition
• Can detect either antibody or antigen
• Can quantify amounts of antigen or antibody
• Easy to perform, inexpensive, and can test many samples quickly
• Plates coated with antigen and gelatin can be stored for later testing
• Very sensitive |
|
|
Term
|
Definition
• Technique for detecting antibodies against multiple antigens in a complex mixture
• Can detect more types of antibodies and are less subject to misinterpretation than other tests |
|
|
Term
| Recent Developments in Immune Testing |
|
Definition
• Development of simple immunoassays that give results in minutes
• Generally not quantitative but are useful in determining a preliminary diagnosis
• Most common are the immunofiltration and immunochromotography assays
– Immunofiltration
• Rapid ELISA that uses antibodies bound to membrane filters rather than polystyrene plates
• Membrane filters have a large surface area making the assay quicker to complete |
|
|
Term
| Recent Developments in Immune Testing 2 |
|
Definition
– Immunochromatography
• Very rapid and easy to read ELISAs
• Antigen solution flows through a porous strip where it encounters antibody labeled with either pink colloidal gold or blue colloidal selenium
• Antigen-Antibody immune complexes flow through a region and encounter antibody against them, resulting in a visible pink or blue line
• Used in pregnancy testing to detect human chorionic gonadotropin (HCG) |
|
|
