Molecular and biological characterization of histidine triad protein in group A streptococci

• Published in: Microbes and infection Vol. 10; no. 4; pp. 414 - 423
• Main Authors: Kunitomo, Eiji, Terao, Yutaka, Okamoto, Shigefumi, Rikimaru, Tetsuya, Hamada, Shigeyuki, Kawabata, Shigetada
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier SAS 01.04.2008; Amsterdam Elsevier; Paris
• Subjects: Animals; Antibodies, Bacterial - blood; Antigens, Bacterial - chemistry; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Antigens, Surface - analysis; Applied microbiology; Bacteriology; Biological and medical sciences; Blotting, Western; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Female; Fundamental and applied biological sciences. Psychology; Gene Order; Group A streptococci; Histidine triad motif; HtpA; Humans; Hydrolases - chemistry; Hydrolases - genetics; Hydrolases - immunology; Mice; Mice, Inbred BALB C; Microbiology; Miscellaneous; Molecular Sequence Data; Molecular Weight; Sequence Analysis, DNA; Shock, Septic - microbiology; Streptococcal Infections - immunology; Streptococcal Infections - prevention & control; Streptococcal Vaccines - immunology; Streptococcus; Streptococcus pneumoniae; Streptococcus pyogenes; Streptococcus pyogenes - chemistry; Streptococcus pyogenes - genetics; Streptococcus pyogenes - immunology; Streptococcus pyogenes - isolation & purification; Survival Analysis; Vaccine; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); PBS; ORFs; FCA; STSS; Group A streptococci; GAS; Streptococcus pyogenes; Histidine triad motif; GBS; Vaccine; HtpA; FIA; Streptococcaceae; Histidine; Aminoacid; Bacteria; Micrococcales; Protein
• ISSN: 1286-4579; 1769-714X
• DOI: 10.1016/j.micinf.2008.01.003

Four Streptococcus pneumoniae genes, phtA, phtB, phtD, and phtE, as well as the slr gene of group A streptococci (GAS), encode proteins with a histidine triad motif (HxxHxH). Pht proteins function as protective antigens against S. pneumoniae infection. A search of the GAS genome database identified a novel protein, HtpA, possessing five histidine triad motifs. The htpA gene was shown to encode a 92.5-kDa protein located downstream of the fbaA and lbp genes, while Western blot analyses revealed that HtpA protein was expressed on the cell surfaces of all group A, B, C, and G streptococcal isolates tested. Immunization of mice with rHtpA induced antigen-specific antibody production and was effective after a single immunization, with antibody titers remaining constant for at least 84 days. In addition, HtpA-immunized mice survived after challenge with GAS strains isolated from patients with streptococcal toxic shock syndrome for significantly longer periods than sham-immunized mice. In that experiment, the HtpA-specific antibody was effectively induced by a single immunization and the specific antibody titer remained constant for at least 84 days. These results indicate that the novel histidine triad protein HtpA is a candidate vaccine for GAS infection.