Abstract: Objective：To investigate the conservation and antigenicity of glutamyl tRNA synthetase (Gts), the candidate target site of potential vaccine for Streptococcus pneumoniae (S.pn), and estimate the age-dependence of the antibody to Gts in human body. Methods：Gts gene from different S.pnserotypes was amplified with PCR, and its conservation was analyzed by sequence alignment. Recombinant Gts protein was obtained through prokaryotic expression system, and was further purified and identified with western blotting. BALB/c mice were immunized with the recombinant protein to prepare the polyclonal antibody to Gts protein and the titer of the antibody was determined. The expression levels of Gts protein in S.pn with different serotypes were determined by western blot. The titers of the antibody to Gts in the serum from the healthy subjects with different age and the patients with S.pn infection were determined by ELISA. Results：The integrated plasmid pET32a(+)-Gts was constructed successfully with S.pn serotype D39 DNA as template, and the recombinant protein Gts with high purity (more than 95%) was obtained after purification of Ni affinity chromatography. The titer of the antibody to Gts in the immunized mice serum reached to 1.024×10⁶(5.12×10⁵,4.096×10⁶). The gene coding region with identical 1 461 bp of length presented in all the 8 different S.pn serotypes, and the sequence homology was 99%. western blotting showed the same band withMr 55 900 presented in the lysate of all the 8 serotypes of S.pn. High titer of antibodies to Gts was detectable in the sera from healthy subjects and S.pninfected patients, and the titer increased with age. Conclusion：The recombinant protein Gts with high immunogenicity and conservation induced the antibody to Gts with high titer in different serotypes of S.pn, indicating that Gts may be a promising candidate protein for vaccine of S.pn.