[Determination of antigenic determinants in the C-terminal 311 amino acids of haps adhesion from nontypeable haemophilus influenza]

ABSTRACT

Haps protein plays central role in initial interaction of nontypeable Haemophilus influenzae [NTHi] with human respiratory epithelial cells. While other surface-exposed proteins of NTHi are highly variable, The HapS domain is highly conserved among H. influenzae strains. Recent studies demonstrated that HapS adhesive activity resides within the C-terminal 311 amino acids of the protein and also they showed that the C-terminal 311 amino acids of HapS [C-Haps] are capable of eliciting a protective immune response against NTHi colonization. The pET24a-chaps plasmid harboring c-haps sequence from NTHi PTCC1766 was constructed. The amino acid sequences of C-Haps of this study was aligned with C-Haps of three NTHi strains [N187, TN106, P860295] and antigenicity plot of studied rC-Haps was done bioinformatic software. The pET24a-chaps expression was conducted in E.coli BL21 [D3E] and its expression was confirmed by SDS-PAGE and Western blotting methods. The rC-Haps was purified via immobilized metal affinity chromatography. Amino acid sequence alignment of rCHaps sequence of current study and rC-Haps from the NTHi strains N187, TN106, P860295 showed more than%97 identity. Antigenicity plot identified 9 common highly antigenic domains that were located exactly in conserved regions among 4 different NTHi strains. Due to presence of highly conserved antigenic epitopes among C-Haps of NTHi PTCC1766 and other NTHi strains, rC-Haps of current study could be theoretically a vaccine candidate against NTHi strains of different geographical areas