Serum concentrations of antibodies against outer membrane protein P6 and its T-and B-combined antigenic epitopes of nontypeable Haemophilus influenzae in children and adults of different ages / 中华微生物学和免疫学杂志

ABSTRACT

Objective To measure the concentrations of antibodies against outer membrane protein P6 and its T-and B-combined antigenic epitopes of nontypeable Haemophilus influenzae ( NTHi) in children and adults of different ages and to evaluate the differences among different subjects for further investigation on NTHi multiple antigenic peptide vaccine .Methods A prokaryotic expression system was established to ex-press the recombinant outer membrane protein P 6 of NTHi.The expressed protein was purified by using Ni-NTA affinity chromatography .T-and B-cell epitopes in protein P6 were predicted with Epitope prediction software 1.0 and ANTIGENIC program and were used to synthesize T-and B-combined antigenic epitopes .A total of 605 subjects aged from 1 day to 103 years old were recruited from October 2013 to March 2014 .Ser-um concentrations of antibodies against protein P 6 and its T-and B-combined antigenic epitopes were meas-ured by using ELISA .Mann-Whitney U test was used to analyze the differences between groups .Pearson product-moment correlation coefficient was used for correlation analysis .Results Four T-and B-combined antigenic epitopes including P 6-2, P6-61, P6-95 and P6-122 were predicted and synthesized .The levels of antibodies against NTHi P6 and P6-2, P6-61, P6-95 and P6-122 were significant lower in the <1 months group than those in the 1-6 months group (all P<0.001) and 7 months-3 years group (all P<0.001).Three groups including 7 months-3 years group , 4-6 years group and 7-14 years group showed significant differ-ences regarding to the antibodies levels , among the 7 months-3 years group showed the highest levels , fol-lowed by the 4-6 years group and the 7-14 years group.However, no significant difference was found be-tween other adjacent groups .Concentrations of antibodies against P 6-2, P6-61, P6-95 and P6-122 were pos-itively correlated with the level of antibody against P 6 (P<0.0001).Conclusion The distribution of anti-bodies against T-and B-combined antigenic epitopes in P6 was highly in accord with those against P6, which indicated good immunogenicity of those epitopes .The highest antibodies levels were found in subjects aged 7 months to 3 years old , which might correlate with the high risk of NTHi infection at that stage .