Lecture 15 Flashcards
explain the basic concept to vaccinology
When we are exposed to a pathogen for the first time, we have no specific IgG antibodies against the pathogen.
As a result, infection can progress to disease.
Over time, we will produce antigen specific IgG antibodies, ie. memory immune response.
The next time we are exposed to this pathogen, we will be protected from disease. However, if we were exposed to a pathogen that did NOT progress to a disease, then our bodies response would simply be the generation of immune memory.
what is the basic concept of vaccines
Its to deliver some or all of the disease organism that imitates the pathogen ( but its not) to the body. This induces protective immune response
what organisms can be used as vaccine tagerts
Both bacteria and viruses contain antigenic components that can be suitable for generation of vaccines.
what are the types of vaccine with example
live-attenuated vaccines, like measles, mumps
inactivated, like hepatitis A, influenza
Recombinant sub-unit, like Hepatitis B
Toxoid, Tetanus
conjugate polysaccharide-protein, like haemophilus influenzea type b
explain live-attenuated vaccine
they are derived form wild (disease causing) viruses or bacterias where we attenuate (weaken) them in a lab by repeated culturing. In order to produce an immune response, live attenuated vaccines must replicate (grow) in the vaccinated person. A relatively small dose of virus or bacteria is given, which replicates in the body and creates enough virus to stimulate an immune response.
The immune response to a live attenuated vaccine is virtually identical to that produced by a natural infection.
what are pros and cons of Live-attenuated vaccines
Pros:
- Cheap
- Adjuvants not necessary
Cons:
- Potential to cause pathology
- Stability
explain inactivated vaccines
produced by growing the virus or bacteria in culture media then inactivating it with and/or chemicals.(usually in formalin). these inactivated vaccines are not alive and cannot replicate. The entire dose of antigen is administered and the entire dose of antigen is administered in the injection. they cannot cause disease from infection, even in an immunodeficient person. In general, the first dose does not produce protective immunity, but only “primes” the immune system. A protective immune response develops after the second or third dose.
what are pros and cons of inactivated of inactivated vaccine
Pros:
- Generally safer
- Improved stability
Cons: - Can be costly - Hypersensitivity
explain recombinant sub unit vaccines
sub unit vaccines are comprised of one antigentic part of the pathogen. These vaccines are produced recombinantly, meaning that other microbes are programmed to produce the desired antigenic component (often proteins or surface polysaccharides).
(A unique type of inactivated subunit vaccine is composed of long chains of sugar molecules that make up the surface capsule of certain bacteria.)
DNA vaccines are a type of recombinant vaccine
what is the immune response to a pure polysaccharide vaccine
typically T-cell independent, which means that these vaccines are able to stimulate B-cells without the assistance of T-helper cells.
explain toxoid vaccines
Toxins are the major virulence factors for some bacteria which cause disease.
Toxoids are forms of chemically altered toxin that are no longer pathogenic.
The antibodies produces in the body as a consequence of toxoid administration neutralize the toxic moiety produced during infection rather than act upon the organism itself. In general toxoids are highly efficacious and safe immunizing agents
what are Conjugate polysaccharide vaccines
They are prepared from extracted cellular fractions e.g. meningococcal vaccine from the polysaccharide antigen of the cell wall, the pneumococcal vaccine from the polysaccharide contained in the capsule of the organism, and hepatitis B polypeptide vaccine.
As carbohydrates themselves do not illicit a T-cell response, the polysaccharides are often chemically attached to a carrier protein. Carrier proteins can often be toxoids, such as Tetanus toxoid.
Their efficacy and safety appear to be high.
explain the types of valency vaccines
