Question

You have a research laboratory and are interested in designing a vaccine to prevent infection by a newly identified species of Streptococcus. This is an extracellular bacterium that has been determined to produce a capsule which may be important in infection by preventing phagocytosis. The capsule is not antigenic and so a vaccine composed of just capsule may not elicit a sufficient immune response. Outline what type of vaccine strategy may be employed and justify your answer based on your knowledge of the immune response to extracellular bacteria and the types of vaccines that may be constructed to prevent infection.

Answer 1

Answer :)

Capsules like polysaccharide (PS) antigens provoke a T-independent immune response, described by lack of memory, and deprived immunogenicity at the limits of life. In this case, polysaccharide vaccines are capable to reduce the incidence of infection. Moreover, the conjugated vaccine is also good if this polysaccharide vaccine has poor immunogenicity. For that, the PS vaccine can conjugate with carrier proteins to elicit a T-dependent immune response. For example, vaccines for meningococcal serogroups are capsule polysaccharide vaccines. Therefore, two types of vaccines can use for such infection.