Glycoconjugate vaccines are a real breakthrough in immunology and increase the effectiveness of the prevention of numerous bacterial diseases, especially in childhood. These vaccines are meant to work against polysaccharides present on the surface of bacteria which, on their own, do not readily stimulate a ferocious immune response. An immune response is enhanced when these polysaccharides are directly linked to a CRM carrier protein, resulting in an efficient immune response with a longer duration.
How Protein Conjugate Vaccines Work
Extracellular polysaccharides of bacteria are quite non-immunogenic, which in simple terms implies that the immune system cannot easily detect them, especially in children and infants. These polysaccharides usually surround bacteria, hiding them from the immune response of the body, and leading to sustained infection. But when polysaccharides are attached to a protein the immune system is activated more vigorously in respect of the same.
This is because the conjugated protein component activates the T-cells which are so crucial in memory and activation of the immune system. In layman’s terms, a protein conjugate vaccine fools the immune system into recognizing a poor activator (the polysaccharide) by linking it to a good activator (the protein). This leads to the development of antibodies to the bacteria and immunity against those diseases by immunization, examples include Hib, pneumococcal diseases, and meningococcal diseases.
CRM197: The Preferred Carrier Protein
CRM197 for example has been employed widely and many carrier proteins exist for conjugate vaccines. CRM197 is inert and primarily derived from diphtheria toxin and has been known to be used for decades in several vaccines. This carrier protein is favoured for several reasons:
Proven Safety: CRM197 is relative to the diphtheria toxin, but it is not toxic can thus is safe to use in human beings, especially to children, and infants.
Strong Immune Response: CRM197 is favoured in the production of a strong T cell-dependent immune response, which when coupled with polysaccharide chemistries creates an effective product. It increases the number of memory cells and this indicates that in case of future infection from the said bacteria, the body can mount a quick defence.
Compatibility with Multiple Vaccines: CRM197 has been used successfully in several different conjugate vaccines; including pneumococcal, meningococcal, and Hib. This property makes it a good candidate for use as a carrier protein in conjugate vaccine production.
Conclusion
Protein conjugate vaccines especially those with CRM197 as the carrier protein have revolutionized the public health service. Some of these diseases that used to be major causes of morbidity and mortality particularly in childhood have greatly been lowered by these vaccines. Rather than simply ensuring the protection of individual persons against specific pathogens, through stirring and long-term immune reactions, these vaccines prevent a range of dangerous bacterial diseases from spreading throughout the population due to herd immunity.
