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ClpP is a stress-inducible protein and proteolytic subunit of the ATP-dependent Clp protease in prokaryotes and eukaryotes. Although its physiological roles in bacterial virul ence were widely studied in various organsims, including Streptococcus pneumonieae, until now the immunological effect has not been investigated. Here, we have examined the cross reactivity of S. pneumoniae ClpP antibody with other organisms’s cell lysate proteins. Although the protein sequence of S. Neumoniae ClpP was highly conserved among various organisms including human, the antibody rasised by S. pneumoniae ClpP was not cross-reacted with other organism’s cell lysates, which were Saccharomyces cerevisiae, human lung A549 cell, Bacillus subtilis, Pseuomonas aeruginosa, E. coli, and Salmonella typhi. It was only reacted with S. pneumoniae and Latobacillus thermophilus. Thus we examined the immunoprotective effect of ClpP by immunizing mice with the purified ClpP. The mean survival time of mouse was significantly increased with the ClpP mmunization. These results suggest that S. pneumoniae ClpP could be used as a vaccine candidate for prevention of S. pneumoniae infection.
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