Two types of immunological responses are manifested on exposure to an antigen:
(a) Primary response and (b) Secondary response
(a) Primary response shows the following unique features:
(i) It is a response following first or initial exposure to an antigen.
(ii) It is a slow response.
(iii) It shows weak potency, there are no antibodies produced initially.
It has a short life (few weeks).
(iv) It has a lower affinity for antigens.
(b) Secondary response is characterized by the following features:
(i) It is a response following a second or subsequent exposure to an antigen.
(ii) It is very rapid
(iii) It is very potent and intense. It forms antibodies for many months.
(v) It has a higher affinity for the antigen.
The hallmark of this response is immunological memory. Memory cells may remain for decades and every new encounter with the same antigen results in the rapid proliferation of these memory cells. Consequently much higher antibody titre is produced causing immediate and rapid response with increased potency and duration.
This also provided the basis for immunization by vaccination against certain diseases viz. small pox, polio, measles, etc. Here , a weakened or killed microbe (an antigen) is injected in the form of a vaccine, in multiple does with periods of several weeks or months between injections causing the 'B' & 'T' cells to activate. Subsequently, when a living pathogen or an infecting microbe is encountered, the body initiates a secondary response, killing it very efficiently.
English physician, Edward Jenner is widely credited as the pioneer of "small pox" vaccine. He is also known as the "Father of Immunology". The term "vaccination" has originated from the latin word "vaccinia" meaning cowpox.
There are various types of vaccines viz. bacterial (e.g., whooping cough), viral, polysaccharide (e.g.,influenza), Toxoid (e.g., diphtheria & tetanus), Recombinant antigen (i.e., hepatitis B), synthetic peptide and DNA vaccines and even "edible" vaccines! AIDS vaccine in tomato, HIV-suppressing in potato, etc. are examples of edible vaccine, BCG vaccine against tuberculosis and Satin vaccine against poliomyelitis are "weakened" or "attenuated" vaccines.
This also provided the basis for immunization by vaccination against certain diseases viz. small pox, polio, measles, etc. Here , a weakened or killed microbe (an antigen) is injected in the form of a vaccine, in multiple does with periods of several weeks or months between injections causing the 'B' & 'T' cells to activate. Subsequently, when a living pathogen or an infecting microbe is encountered, the body initiates a secondary response, killing it very efficiently.
English physician, Edward Jenner is widely credited as the pioneer of "small pox" vaccine. He is also known as the "Father of Immunology". The term "vaccination" has originated from the latin word "vaccinia" meaning cowpox.
There are various types of vaccines viz. bacterial (e.g., whooping cough), viral, polysaccharide (e.g.,influenza), Toxoid (e.g., diphtheria & tetanus), Recombinant antigen (i.e., hepatitis B), synthetic peptide and DNA vaccines and even "edible" vaccines! AIDS vaccine in tomato, HIV-suppressing in potato, etc. are examples of edible vaccine, BCG vaccine against tuberculosis and Satin vaccine against poliomyelitis are "weakened" or "attenuated" vaccines.
No comments:
Post a Comment