Question

The vaccine against Haemophilus influenzae type B is prepared by which of the following methods?

• A. Linking type B capsular polysaccharide to a protein carrier
• B. Modifying type B genetic material to make it less immunogenic
• C. Modifying the tetanus toxoid to act as a vaccine
• D. Both a and b

Answer 1

The correct option is A Linking type B capsular polysaccharide to a protein carrier

Vaccine refers to a product that stimulates a person's immune system to produce immunity to a specific disease, thus protecting the person from that disease. Vaccines for different types of diseases are prepared by various methods.

Haemophilus influenzae type B is known for causing bacterial meningitis. The vaccine for this infection is prepared by linking type B capsular polysaccharide of this bacterium with a carrier protein. This polysaccharide-protein conjugate is found to be more immunogenic as compared to the polysaccharide alone.


Figure: Immune response against antigens

Tetanus is caused by a bacterium, Clostridium tetani. The toxin produced by this bacterium is a proteinaceous neurotoxin affecting the nerve endings of neurons. The inactive form of this toxin is called toxoid which can elicit an immune response. Hence, tetanus is prevented by administering toxoid vaccines.

Tetanus toxoid would act as a vaccine against tetanus (uncontrolled muscle spasms). This toxoid can be used to increase the immunogenic property of the bacterial capsule polysaccharide of Haemophilus, but it cannot act as a substitute for Haemophilus influenzae vaccine.

The genetic material of Haemophilus influenzae type B is not modified to make it less immunogenic during vaccine preparation.