Protective activity of secreted proteins of Streptococcus pneumoniae and Klebsiella pneumoniae

Protective efficacy of secreted proteins of Streptococcus pneumoniae and Klebsiella pneumoniae cultivated on cardiocerebral broth and semisynthetic growth medium respectively was studied in vivo. Fraction with molecular weight 30 - 50 kDa obtained by the method of membrane fractionation had high protective efficacy. Two-dose immunization of mice with this fraction provided 80 - 100% protection from infection by homologous strains of S. pneumoniae and K. pneumoniae. Cross-protective activity of the fraction was revealed when infecting immunized mice by different K-types of K. pneumoniae. Blood sera of mice immunized with 30 - 50 kDa fraction possessed preventive features protecting from infection 90% of animals while 100% of death in the control group. It was determined that protective efficacy of the mentioned fraction was determined by protein-containing antigens because proteolytic disruption of the protein component resulted in loss of protective properties of the preparation.