CONJUGATE VACCINES

Subject : Science & tech

Concept :

A conjugate vaccine is a type of vaccine which combines a weak antigen with a strong antigen as a carrier so that the immune system has a stronger response to the weak antigen.
Vaccines are used to prevent diseases by invoking an immune response to an antigen, the foreign part of a bacteria or virus that the immune system recognizes.
This is usually accomplished with an attenuated or dead version of a pathogenic bacterium or virus in the vaccine, so that the immune system can recognize the antigen later in life.
Many vaccines contain a single antigen that the body will recognize.
However, the antigen of some pathogenic bacteria does not elicit a strong response from the immune system, so a vaccination against this weak antigen would not protect the person later in life. In this case, a conjugate vaccine is used in order to invoke an immune system response against the weak antigen. In a conjugate vaccine, the weak antigen is covalently attached to a strong antigen, thereby eliciting a stronger immunological response to the weak antigen. Most commonly, the weak antigen is a polysaccharide that is attached to strong protein antigen. However, protein and protein/protein conjugates have also been developed.

Approved conjugate vaccines

The most commonly used conjugate vaccine is the Hib conjugate vaccine. Other pathogens that are combined in a conjugate vaccine to increase an immune response are Streptococcus pneumoniae and Neisseria meningitidis, both of which are conjugated to protein carriers like those used in the Hib conjugate vaccine
Another conjugate vaccine is typhoid conjugate vaccine which may be more effective and prevents typhoid fever in many children under the age of five years.
Pneumococcal Conjugate Vaccine (PCV) prevents pneumococcal disease. The vaccine is a mix of several bacteria of the pneumococci family, which are known to cause pneumonia.