Local and systemic immunity againstStreptococcus pneumoniae: Humoral responses against a non-capsulated temperature-sensitive mutant

Temperature-sensitive mutants of Streptococcus pneumoniae were isolated after chemical mutagenesis. Intranasal immunization with temperature-sensitive mutant J/3 induced higher levels of circulating antibody than those obtained after immunization with the heat-killed parental wild type. Moreover, local immunization with mutant J/3 induced high levels of anti-S. pneumoniae IgG and IgA in the lower respiratory tract, whereas only moderate IgG (and no IgA) antibodies were detected in lung lavage fluids from mice immunized intranasally with the heat-killed strain.