The major autolysin, LytA, binds to choline and mediates septation. Ethanolamine-grown bacteria are resistant to LytA. C. Capsule and vaccine 1. 90 serological types based on polysacchairde capsule. Last year, a new vaccine was licensed that is effective in children. This vaccine consists of purified polysaccharide capsule conjugated to DT and is thus a T-cell depended antigen.
Transparent variants colonize the nasopharynx but are avirulent.
Since choline is a major constituent of the teichoic acids, the transparent variants have considerably more choline present and hence choline binding proteins. These 12 proteins are secreted but contain a choline-binding motif that allows them to stick to the cell wall. Vaccination with pneumolysin provides significant protection in a mouse model of infection. Interestingly, pneumolysin is made without an N-terminal signal sequence and is accordingly cytoplasmic. Nevertheless, it is important virulence factor and is released by lysed bacteria.