• Journal of Microbiology
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• v.41 no.2
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• pp.78-82
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• 2003

We identified two proteins in Haemophilus influenzae Rd that exhibited high similarity to two major serine transporters of Escherichia coli (SstT and SdaC). Then, we investigated serine transport in H. influenzae Rd and detected $Na^{+}$-stimulated L-serine transport activity. The optimum NaCl concentration for this stimulation was about 20 mM. The uptake of $Na^{+}$ by H. influenzae Rd was found to be elicited by L-serine influx, which supports the idea that L-serine is transported by a mechanism of $Na^{+}$/serine symport. No uptake of $H^{+}$ elicited by L-serine influx was detected. $Na^{+}$/serine symport activity was not inhibited by other amino acids such as L-threonine or D-serine. Two distinct Km values were obtained from the kinetic analysis of serine transport. Thus, two serine transport pathways may exist in H. influenzae Rd, and it appears that both systems are stimulated by $Na^{+}$.

• Journal of Microbiology
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• v.41 no.3
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• pp.202-206
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• 2003

A protein, exhibiting a high similarity to the major serine transporter of Escherichia coli, SstT, was found in Haemophilus influenzae Rd. A Na$\^$＋/-stimulated serine transport activity was also detected in the cells. The gene (sstT) for the Na$\^$＋//serine symporter from the chromosome of H. influenzae was cloned, and the properties of the transporter investigated. The serine transport activity was stimulated by Na$\^$＋/. The uptake of Na$\^$＋/ was elicited by the addition of serine or threonine into the cells, supporting the idea that these amino acids are transported by a mechanism of Na$\^$＋//substrate symport. No uptake of H$\^$＋/ was elicited by the influx of serine. The serine transport via the SstT of H. influenzae was inhibited by excess threonine, which was used as another substrate. The $K_{m}$ and the $V_{max}$ values for the serine transport were 2.5 ${\mu}$M and 14 nmol/min/mg protein, respectively.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.520-524
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• 2004

A protein that exhibited a high similarity to a major serine transporter of Escherichia coli, SdaC, was found in Haemophilus injluenzae Rd. Also, $Na^+$-stimulated serine transport activity was detected in the cells. The sdaC of H. injluenzae was cloned and the properties of the transporter were investigated. The activity of serine transport was stimulated by $Na^+$. Uptake of $Na^+$ elicited by L-serine influx into cells was also observed, which supports the idea that L-serine is transported by a mechanism of $Na^+$serine symport. No uptake of $H^+$ elicited by L-serine influx was detected. This result was not consistent with that obtained with the homologous protein, SdaC of E. coli, which uses $H^+$as a coupling cation. The serine transport via the SdaC of H. influenzae was not inhibited by other amino acids such as threonine or D-serine like the SdaC of E. coli. Thus, the SdaC of H. influenzae is a $Na^+$-dependent L-serine specific symporter and an unusual natural mutant. The $K_m$ and the $V_{max}$, value for the serine transport in the SdaC of H. influenzae were $7.6\mu$M and 22.9 nmol/min/mg protein, respectively.

• Pediatric Infection and Vaccine
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• v.10 no.1
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• pp.71-80
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• 2003

Purpose : Four kinds of Haemophilus influenzae type b protein conjugate vaccines, PRPD, PRP-T, PRP-OMP and PRP-CRM197, have been developed, and PRP-T vaccines are currently produced by two manufacturer, $ActHib^{(R)}$ by Aventis and $Hiberix^{TM}$ by GlaxoSmith-Kline Biologicals. The purpose of this study is to evaluate the immunogenicity and safety of $Hiberix^{TM}$ in Korean infants. Methods : Seventy-three healthy infants(43 male infants) were recruited for this study after parental informed consent was obtained. Each infant was vaccinated at 2, 4 and 6 months of age with the study vaccine. At each visit, infants were also immunized with DTaP, trivalent oral polio vaccine and hepatitis B vaccine when indicated. The serum anti-PRP antibody was measured at prevaccination, 2 month later after the 2nd dose, and 1 month later after the 3rd dose by the ELISA method. The local and systemic adverse reactions of vaccination were monitored for 3 consecutive days after each immunization. Immunogenicity of vaccine was evaluated in infants who received all the scheduled immunization and the adverse reactions were evaluated for infants who received at least one dose of the study vaccine. Results : Among seventy three infants, enrolled in this study; sixty three(37 male infants) completed all the scheduled immunizations. The geometric mean titer(GMT) of anti-PRP antibodies at prevaccination was 0.17 ${\mu}g/mL$(95% confidence interval[CI]; 0.13~0.22). The GMT of anti-PRP antibodies increased to 4.14 ${\mu}g/mL$(95% CI; 2.65~6.48) at 2 month later after the 2nd dose of PRP-T and 14.65 ${\mu}g/mL$(95% CI; 10.83~19.81) at 1 month later after the 3rd dose. Anti-PRP antibody ${\geq}0.15$ ${\mu}g/mL$, was observed in 98.4%(95% CI; 91.8~100) after 2 doses and 100%(95% CI; 100~100) after 3 doses. Anti-PRP antibody ${\geq}1.0$ ${\mu}g/mL$, was obtained in 77.8%(95% CI; 67.5~88.0) after 2 doses, and 98.4%(95% CI; 95.3~100) after 3 doses. Most of the adverse reaction after vaccination were mild. Irritability, the most common systemic reaction, was observed in 45.5%, followed by drowsiness(30.5%), poor feeding(26.7%) and fever(5.6%). Among the local reactions tenderness was observed in 7.9%, redness(${\geq}5$ mm) in 2.8% and swelling(${\geq}5$ mm) in 1.8%. Conclusion : The PRP-T vaccine used in this study was highly immunogenic and safe in Korean young infants. The finding that high GMT and high frequency of infants with a protective titer achieved after 2 doses is consistent with the previous studies which were done with a PRP-T vaccine of other manufacturer. This study suggests that the immunization schedule of PRP-T vaccine for Korean infants may need re-evaluation.